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North Common SWM Proposed 2018-01-16
Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page i Table of Contents I. Introduction .......................................................................................................................... 1 II. Existing Conditions ................................................................................................................. 4 III. Proposed Conditions .............................................................................................................. 4 IV. Calculations and Design ......................................................................................................... 7 V. MADEP Stormwater Standards Compliance .......................................................................... 11 Figures Figure 1 Location Plan Figure 2 Pre-Development Conditions (North Campus) Figure 3 Existing Conditions (North Campus) Figure 4 Existing Conditions (TCB “Lot 13A” Site) Figure 5 Existing Conditions (TCB “Lot 20” Site) Figure 6 Major Drainage Features (Existing Condition) Figure 7 Grading & Drainage Plan (TCB “Lot 13A” Site) Figure 8 Grading & Drainage Plan (TCB “Lot 20” Site) Figure 9 Pre-Development vs. Proposed Impervious Area (Lot 13A) Figure 10 Existing vs. Proposed Impervious Area (Lot 13A) Figure 11 Pre-Development vs. Existing vs. Proposed Impervious Area (Lot 20) Figure 12 Future Development Plan Figure 13 Pre-Development Drainage Areas Figure 14 Post-Development Drainage Areas Figure 15 Post-Development Drainage Sub-Areas for Pipe Design and Water Quality (Lot 13A) Figure 16 Post-Development Drainage Sub-Areas for Pipe Design and Water Quality (Lot 20) Figure 17 Post-Development Drainage Sub-Area for Stormwater Treatment Chamber Figure 18 Drainage Sub-Areas for Water Quality Volume (Lot 13A) Figure 19 Drainage Sub-Area for Water Quality Volume (Lot 20) Figure 20 Existing Drainage Area to Pecoy Housing Development Figure 21 Proposed Drainage Area to Pecoy Housing Development Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page ii Appendix Appendix A NRCS Soil Report Appendix B Subsurface Investigation Results (Lot 13A) Appendix C Subsurface Investigation Results (Lot 20) Appendix D Stormwater Hydrology Calculations Appendix E Water Quality Calculations Appendix F Outlet Protection Riprap Design Calculations Appendix G Massachusetts Stormwater Checklist Appendix H Stormwater Management System – Operation & Maintenance Plan Appendix I Storm Drain Sizing Calculations Appendix J Impervious Area Tabulation Summary by Gale Associates, Inc. (1/5/2018) Appendix K Stormwater Hydrology Calculations for runoff toward Pecoy Homes Development Referenced Documents Plan Set “New Construction – Village Hill – Northampton, MA” Berkshire Design Group with Davis Square Architects Permit Submission – 10/2017 (Revised 1/2018) Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 1 The Community Builders, Inc. is proposing the construction of new multi-family residential buildings on two lots currently owned by the Massachusetts Economic Development and Finance Agency (Mass Development) within the Village Hill neighborhood of Northampton. The Berkshire Design Group has prepared a Stormwater Management and Erosion and Sedimentation Control Plan for the site, in compliance with the Massachusetts Stormwater Handbook and the Code of the City of Northampton. This report documents the proposed Stormwater Management Plan and that plan’s compliance with those standards. I. Introduction The proposed project is a continuation of the ongoing re-development of the former Northampton State Hospital site, a neighborhood now known as Village Hill. The project proposes two distinct development sites. The first site, known to the project team as “Lot 13A” (Map 31C, Lot 017), is at the north end of Village Hill in the location of a previously approved (but unbuilt) subdivision of single family homes (the “Transformations” project). The proposed project would construct a 65-unit 3-story multifamily apartment building. The site would include an entry road, parking lot, playground and landscaped green space. The second site, known to the project team as “Lot 20”, is one of the last buildable lots within the interior of the Village Hill neighborhood. The lot (Map 38A, Lot 109) is located on the east side of Village Hill Road, between Olander Drive and Moser Street. The work on Lot 20 would construct a 12-unit 2-story multifamily apartment building. The site, which is small relative to the building footprint, would include walkways, a rain garden, and landscaping. The project location is shown in Figure 1. Both sites are located in the “north campus” portion of Village Hill, which encompasses the land north of West Street (Route 66). The pre-development condition, prior to demolition of the state hospital infrastructure, is shown on Figure 2. The existing site of Lot 13A has been disturbed by the now-demolished “Old Main” building that was associated with the Northampton State Hospital. Most of the land area is covered in a field of mowed grass, with some areas of succession meadow/woodland at the periphery. The existing condition of the site is shown on Figure 3, which overlays the property boundaries of existing building lots over an aerial image (c. 2013) of the site. The Lot 13A site is bordered to the west by a housing development by Pecoy Homes (currently under construction), to the north by land that will be transferred to the City for conservation, to the east by a parcel that will be developed in the future as a co-housing residential development, and to the south by a parcel to be retained by Mass Development for construction of single-family homes. These parcels are also shown on Figure 3. The existing topography of Lot 13A is shown on Figure 4. This lot sits at the highest elevation on the site, and slopes off in every direction, with a majority of runoff flowing overland toward the Mill River either directly, or via the large detention basin to the east of the site. The topography of Lot 20 is shown on Figure 5. The existing site of Lot 20 was cleared and graded for future construction during a previous phase of development, and is currently covered by mowed lawn. The existing site generally slopes northwest to southeast, and runoff is captured by the existing storm drains in the surrounding streets and parking lots, which direct it to the existing stormwater management system. The major components of the existing stormwater management infrastructure are shown on Figure 6. With the exception of the Pecoy Homes development at the northwest corner, runoff is managed Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 2 by three detention basins, noted in the figure as Basins #2, 3, and 4 (a previously-proposed basin, #1, was eliminated from the design during an earlier phase). Detention Basin #4 discharges to a swale, carrying water to Basin #2. Basins #2 and #3 discharge off-site. The Pecoy Homes development includes its own stormwater management infrastructure to manage runoff from that development independently from the rest of the site. The grading and drainage plan for Lot 13A is shown on Figure 7. A majority of the site is collected by the proposed storm drains, and discharged to Basin #2. A small portion of the roof of the apartment building falls on a drip strip along the western edge of the building. That roof runoff, plus a portion of the site at the southwest corner flows overland toward the Pecoy Homes development. The parking lot north of the building, as well as a majority of the roof area, drains to a pair of sediment forebays and a rain garden, which include underdrains and overflow drains that are connected to the proposed storm drain system. The grading and drainage plan for Lot 20 is shown on Figure 8. The roof runoff, and a portion of the site, drain to a rain garden at the north end of the site. The rain garden includes an overflow drain that is connected to the existing Village Hill drainage system. This runoff ultimately reaches Basin #4 to the east. No wetlands or buffer zones are located within the proposed limit of disturbance. The Mill River, and its associated riparian zone are located north of the site, and neither is impacted by the proposed work. Figures 9 and 10 compare the new impervious area proposed at Lot 13A with the pre-development and existing conditions, respectively. Figure 11 compares the total impervious area proposed at Lot 20 with the pre-development and existing conditions. Figure 12 shows two additional areas within Village Hill that will be developed after the proposed TCB projects. Immediately south of Lot 13A is a parcel to be retained by Mass Development for the construction of 4 single-family homes of unknown size, that will front on Ford Crossing. Immediately east of Lot 13A is a proposed co-housing development. In 2015, a co-housing development was proposed by Transformations (later Energy Positive Homes), a project which is now defunct. The future co-housing project, to be developed by Sunwood Builders, is expected to be similar in layout to the previous co-housing project, but with fewer units. A conceptual layout of the co-housing project is shown on Figure 12. Soil Data NRCS Soil Survey The NRCS Soil Survey reports that the site consists of a mix of soils. The disturbed area within and adjacent to the location of the former Old Main building is disturbed urban land and fill. Subsequent soil evaluations have determined that this area is best characterized as belonging to Hydrologic Soil Group (HSG) C. The western edge of the site is made up of relatively coarse soils of HSG A. The majority of the remaining portions of the site are made up of relatively fine soils of HSG C, with a small area of medium soils belonging to HSG B. The Soil Report for the site is attached in Appendix A. The boundaries of each soil group are shown on the existing drainage area map (Figure 13). Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 3 Subsurface Exploration A total of 8 test pits were conducted at Lot 13A by Cold Spring Environmental in April 2015. The soil evaluation report is attached in Appendix B.1 The test pits showed some variability, including artificial fill in certain locations, but was generally characterized as moderate to poorly draining sandy loam. Seasonal high groundwater was found at a depth of 24” to 48” across the site. One test pit was conducted near Lot 20 by Beals and Thomas in October 2003. The test pit log and a location plan are attached in Appendix C. This test pit found sandy subsoil with a seasonal high groundwater depth of 7.5’. Previous Analyses The re-development of the Village Hill property has been ongoing for approximately 15 years. The earliest drainage analysis of the proposed development was conducted by Beals and Thomas, and documented in a Notice of Intent submitted in November 2003. The plan of development has been modified numerous times in the ensuing years, and the stormwater management system has been analyzed and re-analyzed several times, both by Berkshire Design and others. This report has utilized those old analyses to re-create the pre-development condition of the site, in order to determine peak runoff rates from the site prior to demolition of the state hospital infrastructure. For the previously-constructed development of Village Hill, Berkshire Design has been provided with tabulation of impervious area by Gale Associates, Inc. dated 1/5/2018. This tabulation is attached in Appendix J. Stormwater Model The pre-development and proposed sites have been analyzed with the HydroCAD stormwater modeling software. A full description of the results of this analysis is included later in this report. The model was built utilizing the following information: · The pre-development site was analyzed based on the inputs identified by Beals and Thomas in the original stormwater report for the site in 2003, and later used by Berkshire Design for the Phase II development in 2007. · The proposed site has been modeled by combining the best-available information on the existing condition and proposed work outside of the TCB project sites. · Impervious areas for the developed portions of the site are based on the Gale Associates tabulation attached in Appendix J. · The surface area covered by detention basins is modeled as impervious area, to reflect the fact that this land will be covered in standing water during intense rainfall. · Aerial images were used to identify the approximate limits of woodland in the un- developed portions of the site. · Within the developed portions of the site, the remaining land after accounting for impervious surfaces, is assumed to be covered in grass. · The existing detention basins have been modeled based on the inputs to previous 1 Note that the report includes 5 additional test pits within the co-housing development site. Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 4 stormwater models of the site, supplemented by as-built drawings and survey information, when available. · The HydroCAD model reflects modifications to Basin #2 was modified in order to provide more freeboard between the emergency spillway and the estimated water level during the 100-year storm. The modification is detailed in the permit plan set, and the proposed structure is included in the stormwater model. II. Pre-Development Conditions The “pre-development condition” is based on the site prior to demolition of the former state hospital buildings. Drainage Areas The pre-development site was divided into drainage areas during the original drainage analysis under the master planning phase. The drainage areas (labeled EDA-1 through EDA-3) are shown on the Existing Drainage Area Plan in Figure 13. A brief description of each drainage area follows. Area EDA-1 This area includes the northwestern quadrant of the site. This area drains toward the north and west, and ultimately discharges to the Mill River to the north. Area EDA-2 This area includes the northeastern portion of the site. This area drains toward the north and east, and ultimately discharges to the Mill River to the north. Area EDA-3 This area includes the southern portion of the site, which drains toward West Street (Route 66). III. Proposed Conditions Proposed drainage areas are delineated in Figure 14. In general, the proposed drainage areas are unchanged from the previous comprehensive stormwater model, produced by Berkshire Design during the Phase II definitive subdivision project in 2007. Some changes to the northern drainage areas were made to account for the work proposed by the current project. A brief summary of each drainage area follows. Drainage Areas Area PDA-1B This area encompasses most of the northwest quadrant of the site, plus the edge of the site beyond the westernmost houses along Moser Street. A small portion of the Lot 13A project is located within this drainage area. The southwest corner of the roof of the apartment building runs off to a drip strip, which discharges down the slope to the west. The southwest corner of the site, including the proposed playground and trail, also drain toward the west. The proposed playground includes two types of surfacing, a permeable pour-in-place rubber surface Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 5 on the slope of a proposed earth berm, and a wood chip carpet on the flat portion of the playground. Both surfaces are designed with approximately 16” of porous material that can collect, store and infiltrate rainfall within the playground footprint. However, the playground is also constructed in an area of cut, and the relatively shallow groundwater at the site may limit the ability of the playground to infiltrate stormwater during times of high groundwater. For these reasons, the playground area is incorporated into the stormwater model as a grass surface, which is the closest match for this condition. The Pecoy Homes development, north of Ford Crossing and west of the Lot 13A site, is located within Area PDA-1B. The Pecoy development was designed to attenuate runoff from the development in order to match the existing condition of that site, which included zero impervious area. This design is documented in a report prepared by Fuss & O’Neil (4/15/2016). For these reasons, both the impervious area and stormwater management system associated with the Pecoy development is omitted from the current analysis, and the area is incorporated into the stormwater model based on ground cover that existed prior to the Pecoy project, as shown on Figure 14. Area PDA-1B includes a portion of the housing lot directly south of the TCB site, which will be developed in the future by Mass Development to include 4 single family homes. Because the layout of the Mass Development project is unknown at this time, the area is incorporated into the stormwater model as 1/8 acre residential (townhouse) lots. This assumes that 65% of the lots will be impervious, which is consistent with the existing single family house lots at Village Hill. Runoff from this drainage area exits the site to the north and west, and ultimately discharges to the Mill River to the north. Area PDA-1C This area includes development in the southwestern quadrant of Village Hill’s north campus. Runoff from this drainage area is discharged to an existing detention basin (Basin #3), located at the corner of Moser Street and Musante Drive, immediately north of the Northampton Community Garden. Impervious area for this drainage area is based on the tabulation provided in the Gale Associates report. The footprint of Basin #3 is modeled as impervious area. The remainder of the site is modeled as grass, divided between the two soil types present within the drainage area. Area PDA-2A This area includes all land at the northern and eastern edges of the site that discharge to the northeast without first passing through Basin #2. The only development planned within this drainage area is a small portion of co-housing buildings at the northern edge of that site, as well as a gravel walking trail the runs toward the northern boundary of the site. The rest of the site will remain in the existing condition, consisting of grass or woods. Area PDA-2B This area includes all of the proposed development for the TCB Lot 13A project, except for the southwest corner of the site, which is included in area PDA-1B above. Area PDA-2B includes a portion of the housing lot directly south of the TCB site, which will be developed in the future by Mass Development to include 4 single family homes. Because the layout of the Mass Development project is unknown at this time, the area is incorporated into the stormwater model as 1/8 acre residential (townhouse) lots. This assumes that 65% of the lots will be Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 6 impervious, which is consistent with the existing single family house lots at Village Hill. Runoff from this drainage area is collected by proposed storm drains, and discharges to the large detention basin at the eastern edge of the site (Basin #2). Water quality treatment for this drainage area is primarily provided by the proposed stormwater treatment chamber, located on the proposed storm drain running through the future co-housing development. This treatment is supplemented by two sediment forebays and a rain garden that collect runoff from the parking lot north of the proposed apartment building, and a majority of the building’s roof. Area PDA-2C This area is in the central portion of the site, and has been near fully-developed under previous projects. The Lot 20 project falls within this drainage area. Runoff from this drainage area is discharged to a large detention basin at the eastern edge of the site (Basin #4), which then discharges to a swale that carries water to Basin #2 further north along the eastern edge of the site. Impervious area for this drainage area is based on the tabulation provided in the Gale Associates report, with two adjustments: 1. The Gale tabulation included the development footprint for Lot 20 as shown on the original Village Hill master plan, which was 6,322 square feet as shown in the Gale report. The proposed work at Lot 20 will actually consist of 7,693 square feet. 2. The Gale tabulation shows the Mass Development parcel immediately south of the Lot 13A project as undeveloped. The stormwater model incorporates the portion of the Mass Development lot located in Area PDA-2C as 1/8 acre residential (townhouse) lots, which consist of 65% impervious area. The footprint of Basin #4 is modeled as impervious area. The remainder of the site is modeled as grass, divided between the two soil types present within the drainage area. Areas PDA-3A & PDA-3B The original stormwater model for the developed site included two drainage areas encompassing the southern portion of the site. These areas discharge to West Street. None of the work proposed by the TCB project (or any anticipated future development) will impact those areas, so they are omitted from this analysis. Water Quality Treatment The water quality of runoff from the Lot 13A project will primarily be managed by the use of a proprietary stormwater treatment chamber (Contech CDS2020-5 or equivalent), sized to remove 80% of total suspended solids. The treatment chamber will be located immediately upstream of Basin #2, and would treat runoff from nearly all impervious surfaces on Lot 13A and the future co- housing project. Additional water quality treatment on Lot 13A will be provided by a rain garden and two sediment forebays that will capture runoff from the parking lot and building roof, for the removal of suspended solids and temperature attenuation. Runoff from nearly all impervious area on Lot 20 will be discharged to a proposed rain garden. Overflow from the rain garden is discharged to the existing storm drain carrying water to Basin #4. This system includes water quality treatment, which will provide for additional removal of suspended solids. Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 7 Calculations that quantify the level of water quality treatment are included in Section IV, below IV. Calculations and Design Water Quantity Drainage calculations were performed on Hydrocad Stormwater Modeling System version 10.0 using Soil Conservation Service (SCS) TR-20 methodology. The SCS method is based on rainfall observations, which were used to develop the Intensity-Duration-Frequency relationship, or IDF curve. The mass curve is a dimensionless distribution of rainfall over time, which indicates the fraction of the rainfall event that occurs at a given time within a 24-hour precipitation event. This synthetic distribution develops peak rates for storms of varying duration and intensities. The SCS distribution provides a cumulative rainfall at any point in time and allows volume-dependent routing runoff calculations to occur. These calculations are included in Appendix D. The watershed boundaries for calculation purposes are divided according to the proposed site grading and the natural limits of the drainage areas. The curve numbers (CNs) and times of concentration for the existing and proposed subcatchment areas are based on the soil type and the existing and proposed cover conditions at the site. Calculations were performed for the 2-, 10-, 25-, and 100-year frequency storms under existing and proposed conditions. The results of the calculations are presented in Table 1 below. Two control points were identified, in order to allow a pre-development/post-development comparison. Discharge Point 1 (DP-1) includes discharges to the northwest. Discharge Point 2 (DP-2) includes all runoff discharged to the northeast. Table 1. Runoff Summary Table for Individual Control Points Condition & Point of Analysis 2-Year Storm 3.00” 10-Year Storm 4.50” 25-Year Storm 2.25” 100-Year Storm 7.00” Peak Flow Rate(cfs) Peak Flow Rate(cfs) Peak Flow Rate(cfs) Peak Flow Rate(cfs) Pre-Development to the Northwest (DP-1)* 7.87 23.49 32.60 55.79 Post-Development to the Northwest (DP-1)* 6.07 16.22 23.71 45.34 Pre-Development to the Northeast (DP-2)* 20.50 46.04 59.97 93.89 Post-Development to the Northeast (DP-2)* 11.99 27.47 44.50 77.42 *Names in parentheses refer to HydroCad model and calculations. The model shows zero increase in stormwater runoff leaving the site for each design storm. Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 8 Storm Drain Sizing Storm drain piping was sized to carry the 25-year design storm without surcharging. A summary of the design calculations is attached in Appendix I. These calculations refer to Figures 15 and 16, which show the contributing drainage sub-area for each proposed inlet. Water Quality The proposed stormwater management system is designed to remove at least 80% total suspended solids. Lot 13A – TSS Removal The Lot 13A site includes 69,132 square feet (1.587 acres) in the proposed condition, as shown on Figure 10. Most of the site runoff will be carried by the proposed storm drains through a Contech CDS2020-5 stormwater treatment chamber, with the remaining areas leaving the site via overland flow. Several portions of the site receive additional water quality treatment from deep-sump hooded catch basins, sediment forebays or rain gardens. The total TSS removal for runoff discharged by this site can be estimated by assessing several distinct treatment trains. Runoff from each drainage sub-area shown in Figure 15 is routed through a treatment train with a particular level of TSS removal. The contribution of the treatment of runoff from drainage sub-area G (encompassing the future co-housing development) is ignored when calculating the average TSS removal across the site; however, this impervious area was included for the calculation that estimates the removal rate for the chamber itself. The remaining impervious areas, which represent areas not captured by proposed BMPs are included with an assumption of zero treatment. TSS removal rates for BMPs are calculated utilizing the standard removal rates from the Stormwater Handbook. For the stormwater treatment chamber, the removal rate was estimated using Contech’s design algorithm, which is based on field testing in accordance with MassDEP standards. The entire drainage area collected by the treatment chamber is shown on Figure 17. A report estimating the average solids removal by the stormwater treatment chamber is included in Appendix E. The treatment efficiency of each of these treatment trains can be estimated, and then a weighted average may be taken to estimate the site-wide water quality treatment efficiency. The Stormwater Handbook water quality worksheets are attached in Appendix E, and are summarized here. Treatment Train 1: Drainage Sub-Area A Impervious Area: 0.195 acres Total TSS Removal: 88% Treatment Train 2: Drainage Sub-Area B Impervious Area: 0.178 acres Total TSS Removal: 88% Treatment Train 3: Drainage Sub-Area C Impervious Area: 0.517 acres Total TSS Removal: 98% Treatment Train 4: Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 9 Drainage Sub-Area D Impervious Area: 0.189 acres Total TSS Removal: 84% Treatment Train 5: Drainage Sub-Area E & F Impervious Area: 0.310 acres2 Total TSS Removal: 88% Treatment Train 6: Remaining Areas Impervious Area: 0.197 acres Total TSS Removal: 0% Site-Wide Weighted Average Impervious Area: 1.587 acres Average TSS Removal: 80% Lot 13A – Water Quality Design Volume The Lot 13A site includes sediment forebays and a rain garden. Figure 18 shows the drainage sub- areas collected by each of these BMPs, as well as the minimum volume and proposed volume for each. In accordance with the Stormwater Handbook, the sediment forebays are sized to capture at least 0.1” times the impervious area. The rain garden is sized to capture the water quality volume, which is 0.5” times the impervious area for this site. Lot 20 Runoff from the Lot 20 project is captured by a proposed rain garden, which is sized to hold the water quality volume of 0.5” times the impervious area. Any overflow from the rain garden is captured by the Village Hill stormwater management system, which includes additional water quality treatment. The drainage sub-area for the rain garden is shown on Figure 19. Figure 19 also reports the minimum volume and design volume of the rain garden. The Lot 20 site includes 7,693 sq. ft. of impervious area, as shown in Figure 11. There is one treatment train for this site, which includes the proposed rain garden. The remaining impervious area drains offsite. While the runoff from those areas is captured by the Village Hill stormwater management system, for the purposes of this analysis, it is assumed that the runoff from those areas is untreated. The treatment efficiency of each of these treatment trains can be estimated, and then a weighted average may be taken to estimate the site-wide water quality treatment efficiency. The Stormwater Handbook water quality worksheets are attached in Appendix E, and are summarized here. Treatment Train 7: Drainage Sub-Area H Impervious Area: 7,117 sq. ft. Total TSS Removal: 90% Treatment Train 8: Remaining Areas Impervious Area: 576 sq. ft. 2 Impervious area for sub-area F excludes the Mass Development lot. Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 10 Total TSS Removal: 0% Site-Wide Weighted Average Impervious Area: 7,693 sq. ft. acres Average TSS Removal: 83% Groundwater Recharge The Lot 13 A site presents a number of challenges that restrict the ability of the site to rely on infiltration and groundwater recharge for stormwater management. The site is predominantly underlain by fine sandy loam soils of Hydrologic Soil Group (HSG) C, with a small area of soils along the southern edge belonging to HSG B. Seasonal high groundwater was estimated to be 24” – 48”below grade. This result was surprising, due to the location of the site at the summit of a hill, sloping away in every direction, but was found consistently across a dozen test pits. Further, because of the location, much of the proposed work will occur in cut, reducing the separation from the surface to the water table. Rain gardens have been incorporated to capture much of the runoff from pavement and roof; however, these rain gardens incorporate underdrains due to the poor soils and high groundwater. It is anticipated that some infiltration will occur during the annual periods of low-groundwater, while infiltration may approach zero during times of high groundwater. Lot 20 is located in a part of the site underlain by sand, with relatively deep groundwater. The proposed site includes 7,117 square feet of impervious area, resulting in a required infiltration volume of 356 cubic feet (based on a “depth factor” of 0.6 inches). The proposed rain garden has a storage volume of 429 cubic feet below the overflow drain inlet. The Lot 20 rain garden has a maximum storage depth of 12”. At a Rawls rate of 8.27 inches per hour, the rain garden is expected to empty in less than 2 hours. Outlet Armoring The primary outlet from the Lot 13A site is a 24” culvert discharging into the existing detention pond (Basin #2). The proposed outlet includes a flared end section and riprap armoring. The riprap size has been designed based on the HEC-11 method. A summary of the design sizing is included in Appendix F. Runoff to Pecoy Development A portion of the Lot 13A site drains toward the Pecoy Homes development to the west. Due to the grading of an access road at the boundary between the two sites, most of the runoff from the Lot 13A site that flows in this direction would be captured by the stormwater management system within the Pecoy development. Drainage areas and stormwater calculations have been prepared to quantify the peak flow rate of runoff from the Lot 13A site toward the Pecoy site, in order to confirm that the proposed work will not increase runoff. Existing and proposed drainage areas are shown in Figures 20 and 21, respectively. HydroCAD calculations area attached in Appendix K. Table 2 summarizes the results. Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 11 Table 2. Summary Table for Runoff toward Pecoy Homes Development Condition & Point of Analysis 2-Year Storm 3.00” 10-Year Storm 4.50” 25-Year Storm 2.25” 100-Year Storm 7.00” Peak Flow Rate(cfs) Peak Flow Rate(cfs) Peak Flow Rate(cfs) Peak Flow Rate(cfs) Existing (PCY-E)* 1.85 4.51 5.99 9.65 Proposed (PCY-P)* 1.70 3.61 4.64 7.12 *Names in parentheses refer to HydroCad model and calculations. V. MADEP Stormwater Standards Compliance The following section details how the project will meet the DEP Stormwater Management Policy’s ten stormwater management standards. A copy of the Massachusetts Stormwater Checklist is attached in Appendix G. LID Low-impact design principals were considered during the development of the stormwater management plan for this project, and have been implemented to the extent practicable. The site includes rain gardens for water quality improvement, and infiltrates runoff where possible. Overall, the Village Hill site represents a cluster development, with relatively high density in developed areas, with large swaths of land placed into permanent conservation. No LID credits are proposed, because none of the proposed features meet the strict criteria for these credits. Standard 1 - Untreated Stormwater Discharge No new outlets that discharge water off-site are proposed. A new outlet discharging to the existing detention pond is proposed, and riprap protection has been designed to prevent erosion at this location. This protection has been designed to resist erosion, as summarized in Appendix F. Standard 2 - Post-Development Peak Discharge Rates The proposed stormwater management system is designed so that post-development peak discharge rates are less than pre-development peak discharge rates leaving the site. These results are discussed in detail under “Peak Runoff Rate” in Section IV, above. Standard 3 - Recharge to Groundwater Groundwater recharge has been incorporated into the project to the extent practicable. The Lot 20 site incorporates a rain garden to infiltrate runoff and meets the required recharge volume, as required under Standard 3, as discussed under Section IV. The Lot 13A site is underlain by relatively fine soils and high groundwater. Most proposed elements of the site are constructed in cut, due to the location of the site on a hilltop. These factors make a significant level of infiltration virtually impossible. Rain gardens have been incorporated to encourage infiltration during times of low groundwater. Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 12 Standard 4 – Water Quality All impervious area is captured by BMPs designed to remove at least 80% TSS, and sized for the 0.5” water quality volume. Further discussion of this standard is included under “Water Quality” in Section IV. Standard 5 - Higher Potential Pollutant Loads The proposed project is not expected to yield high potential pollutant loads. Standard 6 - Protection of Critical Areas The proposed project does not discharge water into or near any critical areas. Standard 7 - Redevelopment Projects This project is partially a redevelopment project. Standard 8 - Erosion/Sediment Control A proposed Erosion & Sediment Control Plan has been developed, and is shown in the plan set. A full Stormwater Pollution Prevention Plan will be developed by the contractor prior to any disturbance of the site. Standard 9 - Operation/Maintenance Plan An Operation and Maintenance Plan for the proposed project is included in Appendix F. It includes general controls for construction and long term maintenance of the stormwater management system. Standard 10 – Prohibition of Illicit Discharges No Illicit Discharge Compliance Statement is included with this report. It will be the responsibility of each parcel owner to submit a statement prior to the discharge of any stormwater to post- construction BMPs. Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. FIGURES Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Appendix A – NRCS Soil Report United States Department of Agriculture A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for Hampshire County, Massachusetts, Central Part Village Hill Subdivision Natural Resources Conservation Service May 15, 2015 Preface Soil surveys contain information that affects land use planning in survey areas. They highlight soil limitations that affect various land uses and provide information about the properties of the soils in the survey areas. Soil surveys are designed for many different users, including farmers, ranchers, foresters, agronomists, urban planners, community officials, engineers, developers, builders, and home buyers. Also, conservationists, teachers, students, and specialists in recreation, waste disposal, and pollution control can use the surveys to help them understand, protect, or enhance the environment. Various land use regulations of Federal, State, and local governments may impose special restrictions on land use or land treatment. Soil surveys identify soil properties that are used in making various land use or land treatment decisions. The information is intended to help the land users identify and reduce the effects of soil limitations on various land uses. The landowner or user is responsible for identifying and complying with existing laws and regulations. Although soil survey information can be used for general farm, local, and wider area planning, onsite investigation is needed to supplement this information in some cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/portal/ nrcs/main/soils/health/) and certain conservation and engineering applications. For more detailed information, contact your local USDA Service Center (http:// offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil Scientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/? cid=nrcs142p2_053951). Great differences in soil properties can occur within short distances. Some soils are seasonally wet or subject to flooding. Some are too unstable to be used as a foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic tank absorption fields. A high water table makes a soil poorly suited to basements or underground installations. The National Cooperative Soil Survey is a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local agencies. The Natural Resources Conservation Service (NRCS) has leadership for the Federal part of the National Cooperative Soil Survey. Information about soils is updated periodically. Updated information is available through the NRCS Web Soil Survey, the site for official soil survey information. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means 2 for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. 3 Contents Preface....................................................................................................................2 How Soil Surveys Are Made..................................................................................5 Soil Map..................................................................................................................7 Soil Map................................................................................................................8 Legend..................................................................................................................9 Map Unit Legend................................................................................................10 Map Unit Descriptions........................................................................................11 Hampshire County, Massachusetts, Central Part...........................................13 1—Water.....................................................................................................13 2A—Pootatuck fine sandy loam, 0 to 3 percent slopes...............................13 4A—Rippowam fine sandy loam, 0 to 3 percent slopes..............................14 8A—Limerick silt loam, 0 to 3 percent slopes.............................................15 30A—Raynham silt loam, 0 to 3 percent slopes.........................................16 98A—Winooski silt loam, 0 to 3 percent slopes..........................................17 220C—Boxford silt loam, 8 to 15 percent slopes........................................18 225A—Belgrade silt loam, 0 to 3 percent slopes........................................19 225B—Belgrade silt loam, 3 to 8 percent slopes........................................20 253A—Hinckley loamy sand, 0 to 3 percent slopes....................................21 253B—Hinckley loamy sand, 3 to 8 percent slopes....................................23 253C—Hinckley loamy sand, 8 to 15 percent slopes..................................24 253E—Hinckley loamy sand, 25 to 35 percent slopes................................25 254A—Merrimac fine sandy loam, 0 to 3 percent slopes............................26 258B—Amostown fine sandy loam, 3 to 8 percent slopes..........................28 260A—Sudbury fine sandy loam, 0 to 3 percent slopes.............................29 311C—Woodbridge fine sandy loam, 8 to 15 percent slopes, very stony...30 651—Udorthents, smoothed.......................................................................31 741A—Amostown-Windsor silty substratum-Urban land complex, 0 to 3 percent slopes.......................................................................................32 References............................................................................................................34 4 How Soil Surveys Are Made Soil surveys are made to provide information about the soils and miscellaneous areas in a specific area. They include a description of the soils and miscellaneous areas and their location on the landscape and tables that show soil properties and limitations affecting various uses. Soil scientists observed the steepness, length, and shape of the slopes; the general pattern of drainage; the kinds of crops and native plants; and the kinds of bedrock. They observed and described many soil profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The profile extends from the surface down into the unconsolidated material in which the soil formed or from the surface down to bedrock. The unconsolidated material is devoid of roots and other living organisms and has not been changed by other biological activity. Currently, soils are mapped according to the boundaries of major land resource areas (MLRAs). MLRAs are geographically associated land resource units that share common characteristics related to physiography, geology, climate, water resources, soils, biological resources, and land uses (USDA, 2006). Soil survey areas typically consist of parts of one or more MLRA. The soils and miscellaneous areas in a survey area occur in an orderly pattern that is related to the geology, landforms, relief, climate, and natural vegetation of the area. Each kind of soil and miscellaneous area is associated with a particular kind of landform or with a segment of the landform. By observing the soils and miscellaneous areas in the survey area and relating their position to specific segments of the landform, a soil scientist develops a concept, or model, of how they were formed. Thus, during mapping, this model enables the soil scientist to predict with a considerable degree of accuracy the kind of soil or miscellaneous area at a specific location on the landscape. Commonly, individual soils on the landscape merge into one another as their characteristics gradually change. To construct an accurate soil map, however, soil scientists must determine the boundaries between the soils. They can observe only a limited number of soil profiles. Nevertheless, these observations, supplemented by an understanding of the soil-vegetation-landscape relationship, are sufficient to verify predictions of the kinds of soil in an area and to determine the boundaries. Soil scientists recorded the characteristics of the soil profiles that they studied. They noted soil color, texture, size and shape of soil aggregates, kind and amount of rock fragments, distribution of plant roots, reaction, and other features that enable them to identify soils. After describing the soils in the survey area and determining their properties, the soil scientists assigned the soils to taxonomic classes (units). Taxonomic classes are concepts. Each taxonomic class has a set of soil characteristics with precisely defined limits. The classes are used as a basis for comparison to classify soils systematically. Soil taxonomy, the system of taxonomic classification used in the United States, is based mainly on the kind and character of soil properties and the arrangement of horizons within the profile. After the soil scientists classified and named the soils in the survey area, they compared the 5 individual soils with similar soils in the same taxonomic class in other areas so that they could confirm data and assemble additional data based on experience and research. The objective of soil mapping is not to delineate pure map unit components; the objective is to separate the landscape into landforms or landform segments that have similar use and management requirements. Each map unit is defined by a unique combination of soil components and/or miscellaneous areas in predictable proportions. Some components may be highly contrasting to the other components of the map unit. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The delineation of such landforms and landform segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, onsite investigation is needed to define and locate the soils and miscellaneous areas. Soil scientists make many field observations in the process of producing a soil map. The frequency of observation is dependent upon several factors, including scale of mapping, intensity of mapping, design of map units, complexity of the landscape, and experience of the soil scientist. Observations are made to test and refine the soil- landscape model and predictions and to verify the classification of the soils at specific locations. Once the soil-landscape model is refined, a significantly smaller number of measurements of individual soil properties are made and recorded. These measurements may include field measurements, such as those for color, depth to bedrock, and texture, and laboratory measurements, such as those for content of sand, silt, clay, salt, and other components. Properties of each soil typically vary from one point to another across the landscape. Observations for map unit components are aggregated to develop ranges of characteristics for the components. The aggregated values are presented. Direct measurements do not exist for every property presented for every map unit component. Values for some properties are estimated from combinations of other properties. While a soil survey is in progress, samples of some of the soils in the area generally are collected for laboratory analyses and for engineering tests. Soil scientists interpret the data from these analyses and tests as well as the field-observed characteristics and the soil properties to determine the expected behavior of the soils under different uses. Interpretations for all of the soils are field tested through observation of the soils in different uses and under different levels of management. Some interpretations are modified to fit local conditions, and some new interpretations are developed to meet local needs. Data are assembled from other sources, such as research information, production records, and field experience of specialists. For example, data on crop yields under defined levels of management are assembled from farm records and from field or plot experiments on the same kinds of soil. Predictions about soil behavior are based not only on soil properties but also on such variables as climate and biological activity. Soil conditions are predictable over long periods of time, but they are not predictable from year to year. For example, soil scientists can predict with a fairly high degree of accuracy that a given soil will have a high water table within certain depths in most years, but they cannot predict that a high water table will always be at a specific level in the soil on a specific date. After soil scientists located and identified the significant natural bodies of soil in the survey area, they drew the boundaries of these bodies on aerial photographs and identified each as a specific map unit. Aerial photographs show trees, buildings, fields, roads, and rivers, all of which help in locating boundaries accurately. Custom Soil Resource Report 6 Soil Map The soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit. 7 8 Custom Soil Resource Report Soil Map 4686800468690046870004687100468720046873004687400468750046876004687700468780046869004687000468710046872004687300468740046875004687600468770046878004687900693000 693100 693200 693300 693400 693500 693600 693700 693800 693900 694000 694100 694200 694300 694400 694500 694600 693000 693100 693200 693300 693400 693500 693600 693700 693800 693900 694000 694100 694200 694300 694400 694500 694600 42° 19' 9'' N 72° 39' 29'' W42° 19' 9'' N72° 38' 16'' W42° 18' 33'' N 72° 39' 29'' W42° 18' 33'' N 72° 38' 16'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 18N WGS84 0 350 700 1400 2100 Feet 0 100 200 400 600 Meters Map Scale: 1:7,680 if printed on A landscape (11" x 8.5") sheet. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:15,800. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: http://websoilsurvey.nrcs.usda.gov Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Hampshire County, Massachusetts, Central Part Survey Area Data: Version 9, Sep 19, 2014 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Mar 28, 2011—Apr 18, 2011 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Custom Soil Resource Report 9 Map Unit Legend Hampshire County, Massachusetts, Central Part (MA609) Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 1 Water 11.0 4.3% 2A Pootatuck fine sandy loam, 0 to 3 percent slopes 8.0 3.1% 4A Rippowam fine sandy loam, 0 to 3 percent slopes 18.3 7.2% 8A Limerick silt loam, 0 to 3 percent slopes 3.4 1.3% 30A Raynham silt loam, 0 to 3 percent slopes 33.5 13.1% 98A Winooski silt loam, 0 to 3 percent slopes 17.0 6.7% 220C Boxford silt loam, 8 to 15 percent slopes 21.1 8.3% 225A Belgrade silt loam, 0 to 3 percent slopes 8.5 3.3% 225B Belgrade silt loam, 3 to 8 percent slopes 14.9 5.8% 253A Hinckley loamy sand, 0 to 3 percent slopes 32.6 12.8% 253B Hinckley loamy sand, 3 to 8 percent slopes 2.1 0.8% 253C Hinckley loamy sand, 8 to 15 percent slopes 4.1 1.6% 253E Hinckley loamy sand, 25 to 35 percent slopes 16.8 6.6% 254A Merrimac fine sandy loam, 0 to 3 percent slopes 6.1 2.4% 258B Amostown fine sandy loam, 3 to 8 percent slopes 4.3 1.7% 260A Sudbury fine sandy loam, 0 to 3 percent slopes 6.7 2.6% 311C Woodbridge fine sandy loam, 8 to 15 percent slopes, very stony 9.2 3.6% 651 Udorthents, smoothed 0.0 0.0% 741A Amostown-Windsor silty substratum-Urban land complex, 0 to 3 percent slopes 37.8 14.8% Totals for Area of Interest 255.3 100.0% Custom Soil Resource Report 10 Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas. An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly Custom Soil Resource Report 11 indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha- Beta association, 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example. Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. Custom Soil Resource Report 12 Hampshire County, Massachusetts, Central Part 1—Water Map Unit Setting National map unit symbol: 9b24 Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 45 to 52 degrees F Frost-free period: 120 to 200 days Farmland classification: Not prime farmland Map Unit Composition Water: 100 percent Estimates are based on observations, descriptions, and transects of the mapunit. 2A—Pootatuck fine sandy loam, 0 to 3 percent slopes Map Unit Setting National map unit symbol: 9b1f Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 45 to 52 degrees F Frost-free period: 140 to 240 days Farmland classification: All areas are prime farmland Map Unit Composition Pootatuck and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Pootatuck Setting Landform: Flood plains Landform position (two-dimensional): Toeslope Landform position (three-dimensional): Tread Down-slope shape: Linear Across-slope shape: Linear Parent material: Loamy alluvium over sandy and gravelly alluvium derived from granite and gneiss Typical profile H1 - 0 to 10 inches: fine sandy loam H2 - 10 to 34 inches: fine sandy loam H3 - 34 to 60 inches: stratified sand to loamy fine sand Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Moderately well drained Runoff class: Very low Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high (0.60 to 6.00 in/hr) Custom Soil Resource Report 13 Depth to water table: About 20 to 34 inches Frequency of flooding: Frequent Frequency of ponding: None Available water storage in profile: Moderate (about 6.5 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 2w Hydrologic Soil Group: B Minor Components Rippowam Percent of map unit: 15 percent Landform: Alluvial flats 4A—Rippowam fine sandy loam, 0 to 3 percent slopes Map Unit Setting National map unit symbol: 9b1n Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 45 to 52 degrees F Frost-free period: 140 to 240 days Farmland classification: Not prime farmland Map Unit Composition Rippowam and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Rippowam Setting Landform: Alluvial flats Landform position (three-dimensional): Dip Down-slope shape: Linear Across-slope shape: Linear Parent material: Loamy alluvium over sandy and gravelly alluvium derived from granite and gneiss Typical profile H1 - 0 to 5 inches: fine sandy loam H2 - 5 to 24 inches: fine sandy loam H3 - 24 to 60 inches: loamy sand Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Poorly drained Runoff class: Very high Custom Soil Resource Report 14 Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high (0.60 to 6.00 in/hr) Depth to water table: About 0 to 18 inches Frequency of flooding: Frequent Frequency of ponding: None Available water storage in profile: Low (about 5.6 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 3w Hydrologic Soil Group: A/D Minor Components Pootatuck Percent of map unit: 5 percent Saco Percent of map unit: 5 percent Landform: Alluvial flats Limerick Percent of map unit: 5 percent Landform: Alluvial flats 8A—Limerick silt loam, 0 to 3 percent slopes Map Unit Setting National map unit symbol: 9b0f Elevation: 50 to 500 feet Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 45 to 52 degrees F Frost-free period: 140 to 240 days Farmland classification: Not prime farmland Map Unit Composition Limerick and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Limerick Setting Landform: Alluvial flats Landform position (three-dimensional): Dip Down-slope shape: Linear Across-slope shape: Linear Parent material: Silty alluvium Typical profile H1 - 0 to 12 inches: silt loam H2 - 12 to 20 inches: very fine sandy loam Custom Soil Resource Report 15 H3 - 20 to 60 inches: silt loam Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Poorly drained Runoff class: Very high Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high (0.60 to 2.00 in/hr) Depth to water table: About 0 to 18 inches Frequency of flooding: Frequent Frequency of ponding: None Available water storage in profile: Very high (about 13.4 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 3w Hydrologic Soil Group: B/D Minor Components Winooski Percent of map unit: 10 percent Saco Percent of map unit: 5 percent Landform: Alluvial flats 30A—Raynham silt loam, 0 to 3 percent slopes Map Unit Setting National map unit symbol: 9b1h Elevation: 50 to 500 feet Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 45 to 52 degrees F Frost-free period: 140 to 240 days Farmland classification: Not prime farmland Map Unit Composition Raynham and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Raynham Setting Landform: Depressions Landform position (three-dimensional): Dip Down-slope shape: Concave Across-slope shape: Linear Parent material: Silty glaciolacustrine deposits Custom Soil Resource Report 16 Typical profile H1 - 0 to 10 inches: silt loam H2 - 10 to 37 inches: silt loam H3 - 37 to 60 inches: stratified loamy fine sand to fine sandy loam to silt loam Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Poorly drained Runoff class: Very high Capacity of the most limiting layer to transmit water (Ksat): Moderately low to moderately high (0.06 to 0.20 in/hr) Depth to water table: About 0 to 31 inches Frequency of flooding: None Frequency of ponding: None Calcium carbonate, maximum in profile: 5 percent Available water storage in profile: High (about 11.8 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 3w Hydrologic Soil Group: C/D Minor Components Belgrade Percent of map unit: 5 percent Maybid Percent of map unit: 5 percent Landform: Depressions Scitico Percent of map unit: 5 percent Landform: Depressions 98A—Winooski silt loam, 0 to 3 percent slopes Map Unit Setting National map unit symbol: 9b2p Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 45 to 52 degrees F Frost-free period: 140 to 240 days Farmland classification: All areas are prime farmland Map Unit Composition Winooski and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Custom Soil Resource Report 17 Description of Winooski Setting Landform: Flood plains Landform position (two-dimensional): Toeslope Landform position (three-dimensional): Tread Down-slope shape: Linear Across-slope shape: Concave Parent material: Silty alluvium Typical profile H1 - 0 to 17 inches: silt loam H2 - 17 to 60 inches: silt loam Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Moderately well drained Runoff class: Very low Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high (0.60 to 6.00 in/hr) Depth to water table: About 18 to 36 inches Frequency of flooding: Occasional Frequency of ponding: None Available water storage in profile: High (about 10.5 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 2w Hydrologic Soil Group: B Minor Components Hadley Percent of map unit: 10 percent Limerick Percent of map unit: 5 percent Landform: Alluvial flats 220C—Boxford silt loam, 8 to 15 percent slopes Map Unit Setting National map unit symbol: 99z7 Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 45 to 52 degrees F Frost-free period: 140 to 240 days Farmland classification: Farmland of statewide importance Map Unit Composition Boxford and similar soils: 85 percent Custom Soil Resource Report 18 Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Boxford Setting Landform: Terraces Landform position (two-dimensional): Summit Landform position (three-dimensional): Tread Down-slope shape: Linear Across-slope shape: Linear Parent material: Hard silty and clayey glaciolacustrine deposits derived from granite and gneiss Typical profile H1 - 0 to 8 inches: silt loam H2 - 8 to 21 inches: silt loam H3 - 21 to 37 inches: silty clay H4 - 37 to 60 inches: silty clay Properties and qualities Slope: 8 to 15 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Moderately well drained Runoff class: High Capacity of the most limiting layer to transmit water (Ksat): Very low to moderately high (0.00 to 0.20 in/hr) Depth to water table: About 19 to 36 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: High (about 9.3 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 3e Hydrologic Soil Group: D Minor Components Unnamed Percent of map unit: 15 percent 225A—Belgrade silt loam, 0 to 3 percent slopes Map Unit Setting National map unit symbol: 99z3 Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 45 to 52 degrees F Frost-free period: 140 to 240 days Farmland classification: All areas are prime farmland Custom Soil Resource Report 19 Map Unit Composition Belgrade and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Belgrade Setting Landform: Terraces Landform position (two-dimensional): Summit Landform position (three-dimensional): Tread Down-slope shape: Convex Across-slope shape: Convex Parent material: Coarse-silty glaciolacustrine deposits Typical profile H1 - 0 to 10 inches: silt loam H2 - 10 to 51 inches: very fine sandy loam H3 - 51 to 60 inches: loamy very fine sand Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Moderately well drained Runoff class: Low Capacity of the most limiting layer to transmit water (Ksat): Moderately low to high (0.06 to 2.00 in/hr) Depth to water table: About 18 to 42 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: High (about 10.7 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 2w Hydrologic Soil Group: C Minor Components Raynham Percent of map unit: 15 percent Landform: Depressions 225B—Belgrade silt loam, 3 to 8 percent slopes Map Unit Setting National map unit symbol: 99z4 Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 45 to 52 degrees F Frost-free period: 140 to 240 days Custom Soil Resource Report 20 Farmland classification: All areas are prime farmland Map Unit Composition Belgrade and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Belgrade Setting Landform: Terraces Landform position (two-dimensional): Summit Landform position (three-dimensional): Tread Down-slope shape: Convex Across-slope shape: Convex Parent material: Coarse-silty glaciolacustrine deposits Typical profile H1 - 0 to 10 inches: silt loam H2 - 10 to 51 inches: very fine sandy loam H3 - 51 to 60 inches: loamy very fine sand Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Moderately well drained Runoff class: Low Capacity of the most limiting layer to transmit water (Ksat): Moderately low to high (0.06 to 2.00 in/hr) Depth to water table: About 18 to 42 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: High (about 10.7 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 2w Hydrologic Soil Group: C Minor Components Raynham Percent of map unit: 15 percent Landform: Depressions 253A—Hinckley loamy sand, 0 to 3 percent slopes Map Unit Setting National map unit symbol: 9b06 Elevation: 0 to 1,000 feet Mean annual precipitation: 40 to 50 inches Custom Soil Resource Report 21 Mean annual air temperature: 45 to 52 degrees F Frost-free period: 140 to 240 days Farmland classification: Farmland of statewide importance Map Unit Composition Hinckley and similar soils: 80 percent Minor components: 20 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Hinckley Setting Landform: Outwash plains Landform position (two-dimensional): Footslope Landform position (three-dimensional): Tread Down-slope shape: Convex Across-slope shape: Convex Parent material: Loose sandy and gravelly glaciofluvial deposits Typical profile H1 - 0 to 8 inches: loamy sand H2 - 8 to 13 inches: loamy sand H3 - 13 to 29 inches: gravelly sand H4 - 29 to 60 inches: Error Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Excessively drained Runoff class: Very low Capacity of the most limiting layer to transmit water (Ksat): High to very high (6.00 to 20.00 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Low (about 3.6 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 3s Hydrologic Soil Group: A Minor Components Windsor Percent of map unit: 10 percent Sudbury Percent of map unit: 10 percent Custom Soil Resource Report 22 253B—Hinckley loamy sand, 3 to 8 percent slopes Map Unit Setting National map unit symbol: 9b07 Elevation: 0 to 1,000 feet Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 45 to 52 degrees F Frost-free period: 140 to 240 days Farmland classification: Farmland of statewide importance Map Unit Composition Hinckley and similar soils: 80 percent Minor components: 20 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Hinckley Setting Landform: Outwash plains Landform position (two-dimensional): Footslope Landform position (three-dimensional): Tread Down-slope shape: Convex Across-slope shape: Convex Parent material: Loose sandy and gravelly glaciofluvial deposits Typical profile H1 - 0 to 8 inches: loamy sand H2 - 8 to 13 inches: loamy sand H3 - 13 to 29 inches: gravelly sand H4 - 29 to 60 inches: Error Properties and qualities Slope: 3 to 8 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Excessively drained Runoff class: Low Capacity of the most limiting layer to transmit water (Ksat): High to very high (6.00 to 20.00 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Low (about 3.6 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 3s Hydrologic Soil Group: A Custom Soil Resource Report 23 Minor Components Sudbury Percent of map unit: 10 percent Windsor Percent of map unit: 10 percent 253C—Hinckley loamy sand, 8 to 15 percent slopes Map Unit Setting National map unit symbol: 9b08 Elevation: 0 to 1,000 feet Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 45 to 52 degrees F Frost-free period: 140 to 240 days Farmland classification: Not prime farmland Map Unit Composition Hinckley and similar soils: 80 percent Minor components: 20 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Hinckley Setting Landform: Outwash plains Landform position (two-dimensional): Footslope Landform position (three-dimensional): Riser Down-slope shape: Convex Across-slope shape: Convex Parent material: Loose sandy and gravelly glaciofluvial deposits Typical profile H1 - 0 to 8 inches: loamy sand H2 - 8 to 13 inches: loamy sand H3 - 13 to 29 inches: gravelly sand H4 - 29 to 60 inches: Error Properties and qualities Slope: 8 to 15 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Excessively drained Runoff class: Low Capacity of the most limiting layer to transmit water (Ksat): High to very high (6.00 to 20.00 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Low (about 3.6 inches) Custom Soil Resource Report 24 Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 4s Hydrologic Soil Group: A Minor Components Windsor Percent of map unit: 15 percent Sudbury Percent of map unit: 5 percent 253E—Hinckley loamy sand, 25 to 35 percent slopes Map Unit Setting National map unit symbol: 9b0b Elevation: 0 to 1,000 feet Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 45 to 52 degrees F Frost-free period: 140 to 240 days Farmland classification: Not prime farmland Map Unit Composition Hinckley and similar soils: 80 percent Minor components: 20 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Hinckley Setting Landform: Outwash plains Landform position (two-dimensional): Footslope Landform position (three-dimensional): Riser Down-slope shape: Linear Across-slope shape: Convex Parent material: Loose sandy and gravelly glaciofluvial deposits Typical profile H1 - 0 to 8 inches: loamy sand H2 - 8 to 13 inches: loamy sand H3 - 13 to 29 inches: gravelly sand H4 - 29 to 60 inches: Error Properties and qualities Slope: 25 to 35 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Excessively drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat): High to very high (6.00 to 20.00 in/hr) Custom Soil Resource Report 25 Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Low (about 3.6 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 7s Hydrologic Soil Group: A Minor Components Merrimac Percent of map unit: 10 percent Windsor Percent of map unit: 10 percent 254A—Merrimac fine sandy loam, 0 to 3 percent slopes Map Unit Setting National map unit symbol: 2tyqr Elevation: 0 to 1,100 feet Mean annual precipitation: 36 to 71 inches Mean annual air temperature: 39 to 55 degrees F Frost-free period: 140 to 240 days Farmland classification: All areas are prime farmland Map Unit Composition Merrimac and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Merrimac Setting Landform: Outwash terraces, eskers, outwash plains, kames, moraines Landform position (two-dimensional): Backslope, footslope, shoulder, summit Landform position (three-dimensional): Side slope, crest, riser, tread Down-slope shape: Convex Across-slope shape: Convex Parent material: Loamy glaciofluvial deposits derived from granite, schist, and gneiss over sandy and gravelly glaciofluvial deposits derived from granite, schist, and gneiss Typical profile Ap - 0 to 10 inches: fine sandy loam Bw1 - 10 to 22 inches: fine sandy loam Bw2 - 22 to 26 inches: stratified gravel to gravelly loamy sand 2C - 26 to 65 inches: stratified gravel to very gravelly sand Custom Soil Resource Report 26 Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Somewhat excessively drained Runoff class: Very low Capacity of the most limiting layer to transmit water (Ksat): Moderately high to very high (1.42 to 99.90 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Calcium carbonate, maximum in profile: 2 percent Salinity, maximum in profile: Nonsaline (0.0 to 1.4 mmhos/cm) Sodium adsorption ratio, maximum in profile: 1.0 Available water storage in profile: Low (about 4.6 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 2s Hydrologic Soil Group: A Minor Components Sudbury Percent of map unit: 5 percent Landform: Terraces, outwash plains, deltas Landform position (two-dimensional): Footslope Landform position (three-dimensional): Tread, dip Down-slope shape: Concave Across-slope shape: Linear Hinckley Percent of map unit: 5 percent Landform: Eskers, outwash plains, kames, deltas Landform position (two-dimensional): Summit, shoulder, backslope Landform position (three-dimensional): Nose slope, side slope, crest, head slope, rise Down-slope shape: Convex Across-slope shape: Convex, linear Agawam Percent of map unit: 3 percent Landform: Outwash terraces, eskers, outwash plains, stream terraces, kames, moraines Landform position (three-dimensional): Rise Down-slope shape: Convex Across-slope shape: Convex Windsor Percent of map unit: 2 percent Landform: Outwash terraces, outwash plains, dunes, deltas Landform position (two-dimensional): Summit Landform position (three-dimensional): Tread, riser Down-slope shape: Linear, convex Across-slope shape: Linear, convex Custom Soil Resource Report 27 258B—Amostown fine sandy loam, 3 to 8 percent slopes Map Unit Setting National map unit symbol: 99z1 Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 45 to 52 degrees F Frost-free period: 140 to 240 days Farmland classification: All areas are prime farmland Map Unit Composition Amostown and similar soils: 75 percent Minor components: 25 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Amostown Setting Landform: Terraces, outwash plains, deltas Landform position (two-dimensional): Summit, footslope Landform position (three-dimensional): Tread Down-slope shape: Convex Across-slope shape: Convex Parent material: Friable sandy glaciofluvial deposits over silty glaciolacustrine deposits Typical profile H1 - 0 to 7 inches: fine sandy loam H2 - 7 to 32 inches: fine sandy loam H3 - 32 to 60 inches: stratified very fine sand to silt loam Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Moderately well drained Runoff class: Low Capacity of the most limiting layer to transmit water (Ksat): Moderately low to moderately high (0.06 to 0.60 in/hr) Depth to water table: About 18 to 36 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: High (about 9.3 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 2w Hydrologic Soil Group: B Custom Soil Resource Report 28 Minor Components Pollux Percent of map unit: 15 percent Agawam Percent of map unit: 10 percent 260A—Sudbury fine sandy loam, 0 to 3 percent slopes Map Unit Setting National map unit symbol: 9b1z Elevation: 0 to 2,100 feet Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 45 to 52 degrees F Frost-free period: 140 to 240 days Farmland classification: All areas are prime farmland Map Unit Composition Sudbury and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Sudbury Setting Landform: Outwash plains Landform position (two-dimensional): Footslope Landform position (three-dimensional): Tread Down-slope shape: Linear Across-slope shape: Concave Parent material: Friable loamy eolian deposits over loose sandy glaciofluvial deposits Typical profile H1 - 0 to 10 inches: fine sandy loam H2 - 10 to 16 inches: fine sandy loam H3 - 16 to 28 inches: gravelly loamy sand H4 - 28 to 60 inches: stratified gravelly sand to very gravelly loamy sand Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Moderately well drained Runoff class: Very low Capacity of the most limiting layer to transmit water (Ksat): High (2.00 to 6.00 in/hr) Depth to water table: About 18 to 36 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Low (about 4.8 inches) Custom Soil Resource Report 29 Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 2w Hydrologic Soil Group: B Minor Components Hinckley Percent of map unit: 5 percent Walpole Percent of map unit: 5 percent Landform: Terraces Merrimac Percent of map unit: 5 percent 311C—Woodbridge fine sandy loam, 8 to 15 percent slopes, very stony Map Unit Setting National map unit symbol: 9b2x Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 45 to 52 degrees F Frost-free period: 140 to 240 days Farmland classification: Not prime farmland Map Unit Composition Woodbridge and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Woodbridge Setting Landform: Hills Landform position (two-dimensional): Backslope Landform position (three-dimensional): Side slope Down-slope shape: Linear Across-slope shape: Concave Parent material: Friable loamy eolian deposits over dense loamy lodgment till derived from granite and gneiss Typical profile H1 - 0 to 7 inches: gravelly fine sandy loam H2 - 7 to 25 inches: gravelly fine sandy loam H3 - 25 to 60 inches: gravelly fine sandy loam Properties and qualities Slope: 8 to 15 percent Percent of area covered with surface fragments: 2.0 percent Depth to restrictive feature: 18 to 35 inches to densic material Custom Soil Resource Report 30 Natural drainage class: Moderately well drained Runoff class: High Capacity of the most limiting layer to transmit water (Ksat): Very low to moderately high (0.00 to 0.20 in/hr) Depth to water table: About 19 to 35 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Low (about 3.4 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 7s Hydrologic Soil Group: C Minor Components Paxton Percent of map unit: 7 percent Charlton Percent of map unit: 5 percent Ridgebury Percent of map unit: 3 percent Landform: Depressions 651—Udorthents, smoothed Map Unit Setting National map unit symbol: 9b23 Elevation: 0 to 3,000 feet Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 45 to 52 degrees F Frost-free period: 120 to 200 days Farmland classification: Not prime farmland Map Unit Composition Udorthents and similar soils: 100 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Udorthents Setting Down-slope shape: Convex Across-slope shape: Convex Parent material: Loamy alluvium and/or sandy glaciofluvial deposits and/or loamy glaciolacustrine deposits and/or loamy marine deposits and/or loamy basal till and/or loamy lodgment till Properties and qualities Slope: 0 to 15 percent Depth to restrictive feature: More than 80 inches Custom Soil Resource Report 31 Natural drainage class: Well drained Runoff class: Medium Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 6s 741A—Amostown-Windsor silty substratum-Urban land complex, 0 to 3 percent slopes Map Unit Setting National map unit symbol: 99z2 Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 45 to 52 degrees F Frost-free period: 120 to 240 days Farmland classification: Not prime farmland Map Unit Composition Amostown and similar soils: 35 percent Urban land: 25 percent Windsor, silty substratum, and similar soils: 25 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Amostown Setting Landform: Terraces, outwash plains, deltas Landform position (two-dimensional): Summit, footslope Landform position (three-dimensional): Tread Down-slope shape: Convex Across-slope shape: Convex Parent material: Friable sandy glaciofluvial deposits over silty glaciolacustrine deposits Typical profile H1 - 0 to 7 inches: fine sandy loam H2 - 7 to 32 inches: fine sandy loam H3 - 32 to 60 inches: stratified very fine sand to silt loam Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Moderately well drained Runoff class: Low Capacity of the most limiting layer to transmit water (Ksat): Moderately low to moderately high (0.06 to 0.60 in/hr) Depth to water table: About 18 to 36 inches Frequency of flooding: None Custom Soil Resource Report 32 Frequency of ponding: None Available water storage in profile: High (about 9.3 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 2w Hydrologic Soil Group: B Description of Windsor, Silty Substratum Setting Landform: Outwash plains Landform position (two-dimensional): Footslope Landform position (three-dimensional): Tread Down-slope shape: Convex Across-slope shape: Convex Parent material: Loose sandy glaciofluvial deposits over silty glaciolacustrine deposits Typical profile H1 - 0 to 8 inches: loamy sand H2 - 8 to 21 inches: loamy sand H3 - 21 to 45 inches: sand H4 - 45 to 60 inches: silt loam Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Somewhat excessively drained Runoff class: Very low Capacity of the most limiting layer to transmit water (Ksat): Moderately high (0.20 to 0.60 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Low (about 5.6 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 3s Hydrologic Soil Group: A Minor Components Enosburg Percent of map unit: 10 percent Landform: Terraces Maybid Percent of map unit: 5 percent Landform: Depressions Custom Soil Resource Report 33 References American Association of State Highway and Transportation Officials (AASHTO). 2004. Standard specifications for transportation materials and methods of sampling and testing. 24th edition. American Society for Testing and Materials (ASTM). 2005. Standard classification of soils for engineering purposes. ASTM Standard D2487-00. Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of wetlands and deep-water habitats of the United States. U.S. Fish and Wildlife Service FWS/OBS-79/31. Federal Register. July 13, 1994. Changes in hydric soils of the United States. Federal Register. September 18, 2002. Hydric soils of the United States. Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric soils in the United States. National Research Council. 1995. Wetlands: Characteristics and boundaries. Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service. U.S. Department of Agriculture Handbook 18. http://www.nrcs.usda.gov/wps/portal/nrcs/ detail/national/soils/?cid=nrcs142p2_054262 Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for making and interpreting soil surveys. 2nd edition. Natural Resources Conservation Service, U.S. Department of Agriculture Handbook 436. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/national/soils/?cid=nrcs142p2_053577 Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of Agriculture, Natural Resources Conservation Service. http://www.nrcs.usda.gov/wps/ portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580 Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and Delaware Department of Natural Resources and Environmental Control, Wetlands Section. United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of Engineers wetlands delineation manual. Waterways Experiment Station Technical Report Y-87-1. United States Department of Agriculture, Natural Resources Conservation Service. National forestry manual. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/ home/?cid=nrcs142p2_053374 United States Department of Agriculture, Natural Resources Conservation Service. National range and pasture handbook. http://www.nrcs.usda.gov/wps/portal/nrcs/ detail/national/landuse/rangepasture/?cid=stelprdb1043084 34 United States Department of Agriculture, Natural Resources Conservation Service. National soil survey handbook, title 430-VI. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/soils/scientists/?cid=nrcs142p2_054242 United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/? cid=nrcs142p2_053624 United States Department of Agriculture, Soil Conservation Service. 1961. Land capability classification. U.S. Department of Agriculture Handbook 210. http:// www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf Custom Soil Resource Report 35 Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Appendix B – Subsurface Investigation Results (Lot 13A) Please feel free to contact us with any questions you may have. rely, d Spring Environmental Consultants, Inc. Alan E. Weiss, M.S., R.S., LSP toik COLD SPRING ENVIRONMENTAL CONSULTANTS INC. • 21E Site Investigations • Subsurface Investigations • Pollution Remediation • LSP on Staff • Forensic Septic Investigations • Percolation Tests • Septic Designs • Regulatory Compliance • Recycling and Solid Waste • Second Opinions April 20, 2015 Mr. Jeffrey Squires The Berkshire Design Group, Inc. 4 Allen Place Northampton, MA 01060 RE: Test Pit & Soil Evaluation Results Proposed Development Village Hill, Northampton, MA CSEC Reference File #115-4538-0417 Greetings Jeff: Background: Cold Spring Environmental, Inc. was contracted to install test pits and perform soil evaluations and particle size analysis in order to evaluate drainage character of soil for the applicability of storm water drainage feasibility at the above referenced property. This task was contracted by you to supplement your work and was conducted on April 2, 2015 by the writer. Included in our job was to complete soil suitability interpretation of underlying soils at the site for drainage structures and storm water management practices. A Site Locus Map (Figure I) and Site Plan (Figure 2, From Berkshire Design Group) is included as Attachment I. The approximate test pit locations are noted on the plan from as selected by Berkshire Design Group Attached. Photos are also provided as Attachment 2. On Site Field Investigation: Test Pit locations were pre-determined by Berkshire Design Group and completed by personnel of this office on April 8, 2015 at the site based on topographic geometry of the property and planned development. thirteen (1-14, excluding #10) were installed as shown on the attached plan). It was later decided by you that the nine of the collected soil samples would be also submitted for particle size analysis at the Umass soil lab in Amherst Ma. Nearly all of the excavations had moderate or poorly permeable sandy loam substrata with perched seasonal high groundwater conditions from 24-48" below grade. Some areas also exhibited fairly disturbed and mixed fill layer of heterogeneous silty and fine sandy glacial till, fill with some crushed concrete brick constituents typical of urban fill and the historically developed and razed nature of much of the southern portion of the subject property. Due to the heterogeneity, this material also had poor drainage qualities and Estimated Seasonal High Groundwater (ESHGW), perched at 24" to 48" below grade. The test pits were excavated using a Bobcat excavator provided by BDG's contracor The soil evaluations followed procedures specified in 310 CMR 15.000for soil evaluations. Overall, native soil types concurred with USDA mapping included Amostown-Windsor Silty Substratum urban complex (Au) consisting of thick mixed deposits underlain by poorly drained soils. The Permeability of the sub soil is generally moderately slow. The Mottling and silty, clayey nature posed by the soils in these locations is the very high ESHGW from 24"-48"below existing grade, may make drainage quite challenging. 350 Old Enfield Road n Bekhertown, MA. 01007 n Phone: 413.323.5957 Fax 413.323.4916 email: aeweiss@charter.net www.coldspringenvironmental.com ATTACHMENT I Figure 1: Site Locus (USGS) Figure 2: Site Layout (labeled Test Pit Locations 1 & 2) Cold Spring Environmental Consultants, Inc. 350 Old Enfield Road Belchertown, MA. 01007 http://www.coldspringenvironmental.com Ph: 413.323.5957 Fax: 413.323.4916 email: aeweiss@charter.net FROM USGS April 2015FIGURE 1—SITE LOCUS Berkshire Design Group Northampton, MA 4GXKUKQPU.CPFUECRG#TEJKVGEVWTG%KXKN'PIKPGGTKPI2NCPPKPI$GTMUJKTG)TQWR+PE&GUKIP6JG.CPF5WTXG[KPI'ZKUVKPI%QPFKVKQPUApplicantEnergy Positive Homes, LLCc/o Transformations, Inc.323 West Main StreetLJĞƌ͕DϬϭϰϯϮOwnerHospital Hill Development, LLCc/o MA Development Finance Agency99 High StreetBoston, MA 01469&'(+0+6+8'2.#0SPECIMEN TREETYP. (SHADED)SPECIMEN TREETYP. (SHADED) ATTACHMENT II Soil Logs and Soil Textural Analysis Reports tp 1 log only t5form12 BDG soil eval form 2014.doc • rev. 3/13 Form 11 – Soil Suitability Assessment for On-Site Sewage Disposal • Page 3 of 8 Commonwealth of Massachusetts City/Town of Northampton Form 11 - Soil Suitability Assessment for On-Site Sewage Disposal C. On-Site Review (continued) Deep Observation Hole Number:1 Depth (in.)Soil Horizon/ Layer Soil Matrix: Color- Moist (Munsell) Redoximorphic Features (mottles)Soil Texture (USDA) Coarse Fragments % by Volume Soil Structure Soil Consistence (Moist) Other Depth Color Percent Gravel Cobbles & Stones 0-7" A 10 yr 3.2 FSL friable 7-24" B 7.5 yr 5.6 24" 2.5Y 4.1 15 FSL till w/fill PLAST. Disturbed 24-40" C1 2.5 yr 4.2 " " " FS 15% sandy moist seeps 22" 40-120"C2 7.5 yr 5.3 " 7.5 yr 5.8 15% FSL 20% Massive platey ESHGW= 24" Additional Notes: tp 4 and tp 2 log only t5form12 BDG soil eval form 2014.doc • rev. 3/13 Form 11 – Soil Suitability Assessment for On-Site Sewage Disposal • Page 3 of 8 Commonwealth of Massachusetts City/Town of Northampton Form 11 - Soil Suitability Assessment for On-Site Sewage Disposal C. On-Site Review (continued) Deep Observation Hole Number:4 & 2 Depth (in.)Soil Horizon/ Layer Soil Matrix: Color- Moist (Munsell) Redoximorphic Features (mottles)Soil Texture (USDA) Coarse Fragments % by Volume Soil Structure Soil Consistence (Moist) Other Depth Color Percent Gravel Cobbles & Stones 0-6" Af 10 YR 3.2 Fill friable fill 6-22" B 7.5 yr 5.6 24" 2.5Y 4.1 20 FSL till w/fill PLAST. Disturbed 22-118" C 2.5 yr 4.2 " " " FSL 15% massive moist seeps 22" --------- --------- ------------ --------- --------- --------- ---------- --------- --------- ----------- ---------ESHGW= 24" 0-36" Af 10 YR. 3.2 fill brick loam mix 36-118" C1 2.5 Y 4.3 30" 2.5 Y 4.1 10 FSL 10% FSL firm moist varved ESHGW= 30" Additional Notes: Soil and Plant Tissue Testing Laboratory 203 Paige Laboratory 161 Holdsworth Way University of Massachusetts Amherst, MA 01003 Phone: (413) 545-2311 e-mail: soiltest@umass.edu website: soiltest.umass.edu Prepared For: 413-323-5957 Sample Information: Sample ID:4 4' Lab Number:X150410-111 Received:4/10/2015 Reported:4/15/2015 Alan Weiss Cold Springs Environmental 350 Old Enfield Rd Belchertown, MA 01007 aweiss@coldspringenvironmental.com Order Number:12753 Particle Size Analysis - Comprehensive USDA Size Fraction Percent of Whole Sample Passing Main Fractions Size (mm)Percent 59.3Sand0.05-2.0 28.9Silt0.002-0.05 11.8Clay<0.002 Sand Fractions Size (mm)Percent 12.0Very Coarse 1.0-2.0 11.5Coarse0.5-1.0 11.4Medium0.25-0.5 14.3Fine0.10-0.25 10.1Very Fine 0.05-0.10 Silt Fractions Size (mm)Percent 10.9Coarse0.02-0.05 14.5Medium0.005-0.02 3.5Fine0.002-0.005 Size (mm)Sieve # Sample Passing Whole Sample % of 2.00 65.2#10 1.00 57.4#18 0.50 49.8#35 0.25 42.4#60 0.10 33.1#140 0.053 26.5#270 0.02 19.420 um 0.005 10.05 um 0.002 7.72 um USDA Textural Class: Gravel Content: (%) gravelly sandy loam 34.8 1 of 1 Lab Number X150410-111Sample ID: 4 4' tp 3 log only t5form12 BDG soil eval form 2014.doc • rev. 3/13 Form 11 – Soil Suitability Assessment for On-Site Sewage Disposal • Page 3 of 8 Commonwealth of Massachusetts City/Town of Northampton Form 11 - Soil Suitability Assessment for On-Site Sewage Disposal C. On-Site Review (continued) Deep Observation Hole Number:3 Depth (in.)Soil Horizon/ Layer Soil Matrix: Color- Moist (Munsell) Redoximorphic Features (mottles)Soil Texture (USDA) Coarse Fragments % by Volume Soil Structure Soil Consistence (Moist) Other Depth Color Percent Gravel Cobbles & Stones 0-8" A 10 yr 3.2 FSL friable 8-26" B 7.5 yr 5.6 20" 2.5Y 4.1 15 FSL till w/fill PLAST. Disturbed 2.5 yr 4.2 " " " moist seeps 24" 26-126"C1 7.5 yr 5.3 " 7.5 yr 5.3 15% FSL 5% 5% Massive platey ESHGW= 20" Additional Notes: tp 5 log only t5form12 BDG soil eval form 2014.doc • rev. 3/13 Form 11 – Soil Suitability Assessment for On-Site Sewage Disposal • Page 3 of 8 Commonwealth of Massachusetts City/Town of Northampton Form 11 - Soil Suitability Assessment for On-Site Sewage Disposal C. On-Site Review (continued) Deep Observation Hole Number:5 Depth (in.)Soil Horizon/ Layer Soil Matrix: Color- Moist (Munsell) Redoximorphic Features (mottles)Soil Texture (USDA) Coarse Fragments % by Volume Soil Structure Soil Consistence (Moist) Other Depth Color Percent Gravel Cobbles & Stones 0-30" Af 10 yr 3.4 FSL buried brick concrete Fill 4' sample 30-126" C1 7.5 yr 5.6 28" 7.5 yr 5.8 10% FSL 10 10 TILL ESHGW= 30" seeps 30" Additional Notes: tp 6 log only t5form12 BDG soil eval form 2014.doc • rev. 3/13 Form 11 – Soil Suitability Assessment for On-Site Sewage Disposal • Page 3 of 8 Commonwealth of Massachusetts City/Town of Northampton Form 11 - Soil Suitability Assessment for On-Site Sewage Disposal C. On-Site Review (continued) Deep Observation Hole Number:6 Depth (in.)Soil Horizon/ Layer Soil Matrix: Color- Moist (Munsell) Redoximorphic Features (mottles)Soil Texture (USDA) Coarse Fragments % by Volume Soil Structure Soil Consistence (Moist) Other Depth Color Percent Gravel Cobbles & Stones 0-3" Af 10 yr 3.4 FSL buried brick concrete Fill/LOAM 4' sample 3-120" FILL 7.5 yr 5.6 34" 7.5 yr 5.8 10% FSL 10 10 MIXED W/TILL ,MASSIVE URBAN FILL ESHGW= 24" seeps 24" Additional Notes: Soil and Plant Tissue Testing Laboratory 203 Paige Laboratory 161 Holdsworth Way University of Massachusetts Amherst, MA 01003 Phone: (413) 545-2311 e-mail: soiltest@umass.edu website: soiltest.umass.edu Prepared For: 413-323-5957 Sample Information: Sample ID:6 4' Lab Number:X150410-104 Received:4/10/2015 Reported:4/15/2015 Alan Weiss Cold Springs Environmental 350 Old Enfield Rd Belchertown, MA 01007 aweiss@coldspringenvironmental.com Order Number:12753 Particle Size Analysis - Comprehensive USDA Size Fraction Percent of Whole Sample Passing Main Fractions Size (mm)Percent 59.6Sand0.05-2.0 26.1Silt0.002-0.05 14.3Clay<0.002 Sand Fractions Size (mm)Percent 7.3Very Coarse 1.0-2.0 12.3Coarse0.5-1.0 14.3Medium0.25-0.5 16.2Fine0.10-0.25 9.4Very Fine 0.05-0.10 Silt Fractions Size (mm)Percent 8.8Coarse0.02-0.05 12.4Medium0.005-0.02 4.9Fine0.002-0.005 Size (mm)Sieve # Sample Passing Whole Sample % of 2.00 79.1#10 1.00 73.3#18 0.50 63.6#35 0.25 52.2#60 0.10 39.4#140 0.053 31.9#270 0.02 25.020 um 0.005 15.25 um 0.002 11.32 um USDA Textural Class: Gravel Content: (%) sandy loam 20.9 1 of 1 Lab Number X150410-104Sample ID: 6 4' tp 7 log only t5form12 BDG soil eval form 2014.doc • rev. 3/13 Form 11 – Soil Suitability Assessment for On-Site Sewage Disposal • Page 3 of 8 Commonwealth of Massachusetts City/Town of Northampton Form 11 - Soil Suitability Assessment for On-Site Sewage Disposal C. On-Site Review (continued) Deep Observation Hole Number:7 Depth (in.)Soil Horizon/ Layer Soil Matrix: Color- Moist (Munsell) Redoximorphic Features (mottles)Soil Texture (USDA) Coarse Fragments % by Volume Soil Structure Soil Consistence (Moist) Other Depth Color Percent Gravel Cobbles & Stones 0-8" A 10 yr 3.2 FSL friable ROOTS 8-32" B 7.5 yr 4.4 MS F sandy sample 4' 32-126" C1 2.5 yr 4.2 36" 7.5 yr 5.8 20% SL 10% 10% sandy TILL seeps 36" MASSIVE ESHGW= 36" Additional Notes: Soil and Plant Tissue Testing Laboratory 203 Paige Laboratory 161 Holdsworth Way University of Massachusetts Amherst, MA 01003 Phone: (413) 545-2311 e-mail: soiltest@umass.edu website: soiltest.umass.edu Prepared For: 413-323-5957 Sample Information: Sample ID:7 Lab Number:X150410-105 Received:4/10/2015 Reported:4/15/2015 Alan Weiss Cold Springs Environmental 350 Old Enfield Rd Belchertown, MA 01007 aweiss@coldspringenvironmental.com Order Number:12753 Particle Size Analysis - Comprehensive USDA Size Fraction Percent of Whole Sample Passing Main Fractions Size (mm)Percent 62.9Sand0.05-2.0 24.2Silt0.002-0.05 12.9Clay<0.002 Sand Fractions Size (mm)Percent 11.0Very Coarse 1.0-2.0 13.8Coarse0.5-1.0 13.7Medium0.25-0.5 15.4Fine0.10-0.25 9.1Very Fine 0.05-0.10 Silt Fractions Size (mm)Percent 8.6Coarse0.02-0.05 11.8Medium0.005-0.02 3.7Fine0.002-0.005 Size (mm)Sieve # Sample Passing Whole Sample % of 2.00 73.7#10 1.00 65.7#18 0.50 55.5#35 0.25 45.4#60 0.10 34.1#140 0.053 27.4#270 0.02 21.020 um 0.005 12.35 um 0.002 9.52 um USDA Textural Class: Gravel Content: (%) sandy loam 26.3 1 of 1 Lab Number X150410-105Sample ID: 7 tp 8 log only t5form12 BDG soil eval form 2014.doc • rev. 3/13 Form 11 – Soil Suitability Assessment for On-Site Sewage Disposal • Page 3 of 8 Commonwealth of Massachusetts City/Town of Northampton Form 11 - Soil Suitability Assessment for On-Site Sewage Disposal C. On-Site Review (continued) Deep Observation Hole Number:8 Depth (in.)Soil Horizon/ Layer Soil Matrix: Color- Moist (Munsell) Redoximorphic Features (mottles)Soil Texture (USDA) Coarse Fragments % by Volume Soil Structure Soil Consistence (Moist) Other Depth Color Percent Gravel Cobbles & Stones 0-96" Af 10 yr 3.4 FSL buried brick concrete Fill 4' sample 96-128" C1 7.5 yr 5.6 28" 7.5 yr 5.8 10% FSL 10 10 TILL ESHGW= 28" seeps 28" Additional Notes: Soil and Plant Tissue Testing Laboratory 203 Paige Laboratory 161 Holdsworth Way University of Massachusetts Amherst, MA 01003 Phone: (413) 545-2311 e-mail: soiltest@umass.edu website: soiltest.umass.edu Prepared For: 413-323-5957 Sample Information: Sample ID:8 Lab Number:X150410-107 Received:4/10/2015 Reported:4/15/2015 Alan Weiss Cold Springs Environmental 350 Old Enfield Rd Belchertown, MA 01007 aweiss@coldspringenvironmental.com Order Number:12753 Particle Size Analysis - Comprehensive USDA Size Fraction Percent of Whole Sample Passing Main Fractions Size (mm)Percent 71.2Sand0.05-2.0 22.7Silt0.002-0.05 6.1Clay<0.002 Sand Fractions Size (mm)Percent 10.4Very Coarse 1.0-2.0 14.1Coarse0.5-1.0 15.7Medium0.25-0.5 19.3Fine0.10-0.25 11.7Very Fine 0.05-0.10 Silt Fractions Size (mm)Percent 11.8Coarse0.02-0.05 9.1Medium0.005-0.02 1.8Fine0.002-0.005 Size (mm)Sieve # Sample Passing Whole Sample % of 2.00 77.7#10 1.00 69.6#18 0.50 58.6#35 0.25 46.4#60 0.10 31.4#140 0.053 22.4#270 0.02 13.220 um 0.005 6.15 um 0.002 4.72 um USDA Textural Class: Gravel Content: (%) sandy loam 22.3 1 of 1 Lab Number X150410-107Sample ID: 8 tp 11 log only t5form12 BDG soil eval form 2014.doc • rev. 3/13 Form 11 – Soil Suitability Assessment for On-Site Sewage Disposal • Page 3 of 8 Commonwealth of Massachusetts City/Town of Northampton Form 11 - Soil Suitability Assessment for On-Site Sewage Disposal C. On-Site Review (continued) Deep Observation Hole Number:9 Depth (in.)Soil Horizon/ Layer Soil Matrix: Color- Moist (Munsell) Redoximorphic Features (mottles)Soil Texture (USDA) Coarse Fragments % by Volume Soil Structure Soil Consistence (Moist) Other Depth Color Percent Gravel Cobbles & Stones 0-48" Af 10 yr 3.4 FSL buried brick concrete Fill 4' sample 48-128" C1 7.5 yr 5.6 48" 7.5 yr 5.8 10% FS 10 10 granular ESHGW= 48" seeps 50" Additional Notes: Soil and Plant Tissue Testing Laboratory 203 Paige Laboratory 161 Holdsworth Way University of Massachusetts Amherst, MA 01003 Phone: (413) 545-2311 e-mail: soiltest@umass.edu website: soiltest.umass.edu Prepared For: 413-323-5957 Sample Information: Sample ID:9 4' Lab Number:X150410-109 Received:4/10/2015 Reported:4/15/2015 Alan Weiss Cold Springs Environmental 350 Old Enfield Rd Belchertown, MA 01007 aweiss@coldspringenvironmental.com Order Number:12753 Particle Size Analysis - Comprehensive USDA Size Fraction Percent of Whole Sample Passing Main Fractions Size (mm)Percent 63.4Sand0.05-2.0 23.3Silt0.002-0.05 13.3Clay<0.002 Sand Fractions Size (mm)Percent 10.4Very Coarse 1.0-2.0 14.1Coarse0.5-1.0 14.8Medium0.25-0.5 15.3Fine0.10-0.25 8.8Very Fine 0.05-0.10 Silt Fractions Size (mm)Percent 8.0Coarse0.02-0.05 10.8Medium0.005-0.02 4.5Fine0.002-0.005 Size (mm)Sieve # Sample Passing Whole Sample % of 2.00 39.1#10 1.00 35.0#18 0.50 29.5#35 0.25 23.7#60 0.10 17.8#140 0.053 14.3#270 0.02 11.220 um 0.005 7.05 um 0.002 5.22 um USDA Textural Class: Gravel Content: (%) gravelly sandy loam 60.9 1 of 1 Lab Number X150410-109Sample ID: 9 4' tp 11 log only t5form12 BDG soil eval form 2014.doc • rev. 3/13 Form 11 – Soil Suitability Assessment for On-Site Sewage Disposal • Page 3 of 8 Commonwealth of Massachusetts City/Town of Northampton Form 11 - Soil Suitability Assessment for On-Site Sewage Disposal C. On-Site Review (continued) Deep Observation Hole Number:11 Depth (in.)Soil Horizon/ Layer Soil Matrix: Color- Moist (Munsell) Redoximorphic Features (mottles)Soil Texture (USDA) Coarse Fragments % by Volume Soil Structure Soil Consistence (Moist) Other Depth Color Percent Gravel Cobbles & Stones 0-64" Af 10 yr 3.6 FSL buried brick Fill 3' sample 64-120" C1 7.5 yr 5.6 48" 7.5 yr 5.8 20% FSL 10 10 massive till loose disturbed some silt ESHGW= 48" 8' sample Additional Notes: Soil and Plant Tissue Testing Laboratory 203 Paige Laboratory 161 Holdsworth Way University of Massachusetts Amherst, MA 01003 Phone: (413) 545-2311 e-mail: soiltest@umass.edu website: soiltest.umass.edu Prepared For: 413-323-5957 Sample Information: Sample ID:11 3' Lab Number:X150410-106 Received:4/10/2015 Reported:4/15/2015 Alan Weiss Cold Springs Environmental 350 Old Enfield Rd Belchertown, MA 01007 aweiss@coldspringenvironmental.com Order Number:12753 Particle Size Analysis - Comprehensive USDA Size Fraction Percent of Whole Sample Passing Main Fractions Size (mm)Percent 74.3Sand0.05-2.0 16.3Silt0.002-0.05 9.4Clay<0.002 Sand Fractions Size (mm)Percent 13.3Very Coarse 1.0-2.0 17.6Coarse0.5-1.0 17.5Medium0.25-0.5 17.4Fine0.10-0.25 8.4Very Fine 0.05-0.10 Silt Fractions Size (mm)Percent 7.2Coarse0.02-0.05 7.2Medium0.005-0.02 1.9Fine0.002-0.005 Size (mm)Sieve # Sample Passing Whole Sample % of 2.00 69.9#10 1.00 60.6#18 0.50 48.3#35 0.25 36.1#60 0.10 23.9#140 0.053 18.0#270 0.02 12.920 um 0.005 7.95 um 0.002 6.62 um USDA Textural Class: Gravel Content: (%) coarse sandy loam 30.1 1 of 1 Lab Number X150410-106Sample ID: 11 3' Soil and Plant Tissue Testing Laboratory 203 Paige Laboratory 161 Holdsworth Way University of Massachusetts Amherst, MA 01003 Phone: (413) 545-2311 e-mail: soiltest@umass.edu website: soiltest.umass.edu Prepared For: 413-323-5957 Sample Information: Sample ID:11 8' Lab Number:X150410-108 Received:4/10/2015 Reported:4/15/2015 Alan Weiss Cold Springs Environmental 350 Old Enfield Rd Belchertown, MA 01007 aweiss@coldspringenvironmental.com Order Number:12753 Particle Size Analysis - Comprehensive USDA Size Fraction Percent of Whole Sample Passing Main Fractions Size (mm)Percent 77.4Sand0.05-2.0 14.7Silt0.002-0.05 7.8Clay<0.002 Sand Fractions Size (mm)Percent 16.5Very Coarse 1.0-2.0 18.4Coarse0.5-1.0 17.1Medium0.25-0.5 17.1Fine0.10-0.25 8.3Very Fine 0.05-0.10 Silt Fractions Size (mm)Percent 6.0Coarse0.02-0.05 7.6Medium0.005-0.02 1.2Fine0.002-0.005 Size (mm)Sieve # Sample Passing Whole Sample % of 2.00 72.3#10 1.00 60.3#18 0.50 47.0#35 0.25 34.7#60 0.10 22.3#140 0.053 16.3#270 0.02 12.020 um 0.005 6.55 um 0.002 5.62 um USDA Textural Class: Gravel Content: (%) coarse sandy loam 27.7 1 of 1 Lab Number X150410-108Sample ID: 11 8' tp 13 log only t5form12 BDG soil eval form 2014.doc • rev. 3/13 Form 11 – Soil Suitability Assessment for On-Site Sewage Disposal • Page 3 of 8 Commonwealth of Massachusetts City/Town of Northampton Form 11 - Soil Suitability Assessment for On-Site Sewage Disposal C. On-Site Review (continued) Deep Observation Hole Number:12 Depth (in.)Soil Horizon/ Layer Soil Matrix: Color- Moist (Munsell) Redoximorphic Features (mottles)Soil Texture (USDA) Coarse Fragments % by Volume Soil Structure Soil Consistence (Moist) Other Depth Color Percent Gravel Cobbles & Stones 0-12" A 10 yr 3.3 FSL friable Roots 12-26" B 10 yr 4.6 FS F sandy 26-126" C1 10 yr 4.3 28" 7.5 yr 5.6 20% FSL 10 10 massive till some silt ESHGW= 28" Additional Notes: Soil and Plant Tissue Testing Laboratory 203 Paige Laboratory 161 Holdsworth Way University of Massachusetts Amherst, MA 01003 Phone: (413) 545-2311 e-mail: soiltest@umass.edu website: soiltest.umass.edu Prepared For: 413-323-5957 Sample Information: Sample ID:12 4' Lab Number:X150410-103 Received:4/10/2015 Reported:4/15/2015 Alan Weiss Cold Springs Environmental 350 Old Enfield Rd Belchertown, MA 01007 aweiss@coldspringenvironmental.com Order Number:12753 Particle Size Analysis - Comprehensive USDA Size Fraction Percent of Whole Sample Passing Main Fractions Size (mm)Percent 60.1Sand0.05-2.0 27.9Silt0.002-0.05 12.0Clay<0.002 Sand Fractions Size (mm)Percent 10.3Very Coarse 1.0-2.0 11.5Coarse0.5-1.0 12.3Medium0.25-0.5 15.7Fine0.10-0.25 10.4Very Fine 0.05-0.10 Silt Fractions Size (mm)Percent 10.6Coarse0.02-0.05 13.8Medium0.005-0.02 3.5Fine0.002-0.005 Size (mm)Sieve # Sample Passing Whole Sample % of 2.00 78.0#10 1.00 70.0#18 0.50 61.0#35 0.25 51.4#60 0.10 39.2#140 0.053 31.1#270 0.02 22.820 um 0.005 12.15 um 0.002 9.42 um USDA Textural Class: Gravel Content: (%) sandy loam 22.0 1 of 1 Lab Number X150410-103Sample ID: 12 4' tp 13 log only t5form12 BDG soil eval form 2014.doc • rev. 3/13 Form 11 – Soil Suitability Assessment for On-Site Sewage Disposal • Page 3 of 8 Commonwealth of Massachusetts City/Town of Northampton Form 11 - Soil Suitability Assessment for On-Site Sewage Disposal C. On-Site Review (continued) Deep Observation Hole Number:13 Depth (in.)Soil Horizon/ Layer Soil Matrix: Color- Moist (Munsell) Redoximorphic Features (mottles)Soil Texture (USDA) Coarse Fragments % by Volume Soil Structure Soil Consistence (Moist) Other Depth Color Percent Gravel Cobbles & Stones 0-8" A 10 yr 3.2 FSL friable 8-30" B 10 yr 4.3 FS 5% granular F sandy little silt 30-126" C1 2.5 yr 4.2 26" 2.5 y 4.1 20% silt loam silty & clayey varved seeps 26" 7.5 yr 5.8 ESHGW= 26" Additional Notes: tp 14 log only t5form12 BDG soil eval form 2014.doc • rev. 3/13 Form 11 – Soil Suitability Assessment for On-Site Sewage Disposal • Page 3 of 8 Commonwealth of Massachusetts City/Town of Northampton Form 11 - Soil Suitability Assessment for On-Site Sewage Disposal C. On-Site Review (continued) Deep Observation Hole Number:14 Depth (in.)Soil Horizon/ Layer Soil Matrix: Color- Moist (Munsell) Redoximorphic Features (mottles)Soil Texture (USDA) Coarse Fragments % by Volume Soil Structure Soil Consistence (Moist) Other Depth Color Percent Gravel Cobbles & Stones 0-4" A 10 yr 3.2 FSL friable 4-22" B 10 yr 4.6 FSL F sandy little silt 22-120 C1 2.5 yr 4.2 40" 7.5 yr 5.8 20% FS 15% F sandy granular seeps 48" varved ESHGW= 40" Additional Notes: ATTACHMENT III Photographs TP-1 Village Hill Northampton, MA 04.2.2015 TP-2 Village Hill Northampton, MA 04.2.2015 TP-3 Village Hill Northampton, MA 04.2.2015 TP-4 Village Hill Northampton, MA 04.2.2015 TP-5 samples Village Hill Northampton, MA 04.2.2015 TP-6 Village Hill Northampton, MA 04.2.2015 TP-6 pic 2 Village Hill Northampton, MA 04.2.2015 TP-7 Village Hill Northampton, MA 04.2.2015 TP-8 Village Hill Northampton, MA 04.2.2015 TP-9 Village Hill Northampton, MA 04.2.2015 TP-12 Village Hill Northampton, MA 04.2.2015 11 TP-11 Village Hill Northampton, MA 04.2.2015 2 TP-14 Village Hill Northampton, MA 04.2.2015 Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Appendix C – Subsurface Investigation Results (Lot 20) Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Appendix D – Stormwater Hydrology Calculations EDA-1 Area in NW corner of existing site EDA-2 Area in NE corner of existing site DP-1 Control Point for existing runoff DP-2 Control point for existing runoff Routing Diagram for Village Hill - TCB - Pre-Development Prepared by Microsoft, Printed 1/17/2018 HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Subcat Reach Pond Link Type III 24-hr 2-yr Rainfall=3.00"Village Hill - TCB - Pre-Development Printed 1/17/2018Prepared by Microsoft Page 2HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=16.800 ac 26.79% Impervious Runoff Depth>0.58"Subcatchment EDA-1: Area in NW corner Flow Length=750' Tc=10.1 min CN=67 Runoff=7.87 cfs 0.817 af Runoff Area=22.600 ac 15.93% Impervious Runoff Depth>0.96"Subcatchment EDA-2: Area in NE corner Flow Length=680' Tc=10.4 min CN=75 Runoff=20.50 cfs 1.805 af Inflow=7.87 cfs 0.817 afReach DP-1: Control Point for existing runoff Outflow=7.87 cfs 0.817 af Inflow=20.50 cfs 1.805 afReach DP-2: Control point for existing runoff Outflow=20.50 cfs 1.805 af Type III 24-hr 2-yr Rainfall=3.00"Village Hill - TCB - Pre-Development Printed 1/17/2018Prepared by Microsoft Page 3HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Subcatchment EDA-1: Area in NW corner of existing site Area in NW corner of existing site Runoff = 7.87 cfs @ 12.17 hrs, Volume= 0.817 af, Depth> 0.58" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-yr Rainfall=3.00" Area (ac) CN Description 0.700 98 Paved parking & roofs 3.800 98 Paved parking & roofs 2.700 39 >75% Grass cover, Good, HSG A 5.000 74 >75% Grass cover, Good, HSG C 2.700 30 Woods, Good, HSG A 0.400 55 Woods, Good, HSG B 1.500 70 Woods, Good, HSG C 16.800 67 Weighted Average 12.300 73.21% Pervious Area 4.500 26.79% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.5 50 0.0250 0.11 Sheet Flow, Sheet Flow to the NW corner of property Grass: Dense n= 0.240 P2= 3.20" 0.7 130 0.0380 3.14 Shallow Concentrated Flow, Flow to NW of property Unpaved Kv= 16.1 fps 1.0 380 0.1630 6.50 Shallow Concentrated Flow, Flow to NW of property Unpaved Kv= 16.1 fps 0.9 190 0.0500 3.60 Shallow Concentrated Flow, Flow towards control point Unpaved Kv= 16.1 fps 10.1 750 Total Summary for Subcatchment EDA-2: Area in NE corner of existing site Runoff = 20.50 cfs @ 12.16 hrs, Volume= 1.805 af, Depth> 0.96" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-yr Rainfall=3.00" Area (ac) CN Description 2.800 61 >75% Grass cover, Good, HSG B 0.100 55 Woods, Good, HSG B 0.600 98 Paved parking & roofs 10.800 74 >75% Grass cover, Good, HSG C 5.300 70 Woods, Good, HSG C 3.000 98 Paved parking & roofs 22.600 75 Weighted Average 19.000 84.07% Pervious Area 3.600 15.93% Impervious Area Type III 24-hr 2-yr Rainfall=3.00"Village Hill - TCB - Pre-Development Printed 1/17/2018Prepared by Microsoft Page 4HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.9 50 0.0220 0.11 Sheet Flow, Flow to the east down dense grass hill Grass: Dense n= 0.240 P2= 3.20" 1.4 370 0.0780 4.50 Shallow Concentrated Flow, Flow to the east Unpaved Kv= 16.1 fps 1.1 260 0.0620 4.01 Shallow Concentrated Flow, Flow to control point Unpaved Kv= 16.1 fps 10.4 680 Total Summary for Reach DP-1: Control Point for existing runoff Inflow Area = 16.800 ac, 26.79% Impervious, Inflow Depth > 0.58" for 2-yr event Inflow = 7.87 cfs @ 12.17 hrs, Volume= 0.817 af Outflow = 7.87 cfs @ 12.17 hrs, Volume= 0.817 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Reach DP-2: Control point for existing runoff Inflow Area = 22.600 ac, 15.93% Impervious, Inflow Depth > 0.96" for 2-yr event Inflow = 20.50 cfs @ 12.16 hrs, Volume= 1.805 af Outflow = 20.50 cfs @ 12.16 hrs, Volume= 1.805 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.50"Village Hill - TCB - Pre-Development Printed 1/17/2018Prepared by Microsoft Page 5HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=16.800 ac 26.79% Impervious Runoff Depth>1.46"Subcatchment EDA-1: Area in NW corner Flow Length=750' Tc=10.1 min CN=67 Runoff=23.49 cfs 2.045 af Runoff Area=22.600 ac 15.93% Impervious Runoff Depth>2.05"Subcatchment EDA-2: Area in NE corner Flow Length=680' Tc=10.4 min CN=75 Runoff=46.04 cfs 3.854 af Inflow=23.49 cfs 2.045 afReach DP-1: Control Point for existing runoff Outflow=23.49 cfs 2.045 af Inflow=46.04 cfs 3.854 afReach DP-2: Control point for existing runoff Outflow=46.04 cfs 3.854 af Type III 24-hr 10-yr Rainfall=4.50"Village Hill - TCB - Pre-Development Printed 1/17/2018Prepared by Microsoft Page 6HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Subcatchment EDA-1: Area in NW corner of existing site Area in NW corner of existing site Runoff = 23.49 cfs @ 12.16 hrs, Volume= 2.045 af, Depth> 1.46" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.50" Area (ac) CN Description 0.700 98 Paved parking & roofs 3.800 98 Paved parking & roofs 2.700 39 >75% Grass cover, Good, HSG A 5.000 74 >75% Grass cover, Good, HSG C 2.700 30 Woods, Good, HSG A 0.400 55 Woods, Good, HSG B 1.500 70 Woods, Good, HSG C 16.800 67 Weighted Average 12.300 73.21% Pervious Area 4.500 26.79% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.5 50 0.0250 0.11 Sheet Flow, Sheet Flow to the NW corner of property Grass: Dense n= 0.240 P2= 3.20" 0.7 130 0.0380 3.14 Shallow Concentrated Flow, Flow to NW of property Unpaved Kv= 16.1 fps 1.0 380 0.1630 6.50 Shallow Concentrated Flow, Flow to NW of property Unpaved Kv= 16.1 fps 0.9 190 0.0500 3.60 Shallow Concentrated Flow, Flow towards control point Unpaved Kv= 16.1 fps 10.1 750 Total Summary for Subcatchment EDA-2: Area in NE corner of existing site Runoff = 46.04 cfs @ 12.15 hrs, Volume= 3.854 af, Depth> 2.05" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.50" Area (ac) CN Description 2.800 61 >75% Grass cover, Good, HSG B 0.100 55 Woods, Good, HSG B 0.600 98 Paved parking & roofs 10.800 74 >75% Grass cover, Good, HSG C 5.300 70 Woods, Good, HSG C 3.000 98 Paved parking & roofs 22.600 75 Weighted Average 19.000 84.07% Pervious Area 3.600 15.93% Impervious Area Type III 24-hr 10-yr Rainfall=4.50"Village Hill - TCB - Pre-Development Printed 1/17/2018Prepared by Microsoft Page 7HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.9 50 0.0220 0.11 Sheet Flow, Flow to the east down dense grass hill Grass: Dense n= 0.240 P2= 3.20" 1.4 370 0.0780 4.50 Shallow Concentrated Flow, Flow to the east Unpaved Kv= 16.1 fps 1.1 260 0.0620 4.01 Shallow Concentrated Flow, Flow to control point Unpaved Kv= 16.1 fps 10.4 680 Total Summary for Reach DP-1: Control Point for existing runoff Inflow Area = 16.800 ac, 26.79% Impervious, Inflow Depth > 1.46" for 10-yr event Inflow = 23.49 cfs @ 12.16 hrs, Volume= 2.045 af Outflow = 23.49 cfs @ 12.16 hrs, Volume= 2.045 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Reach DP-2: Control point for existing runoff Inflow Area = 22.600 ac, 15.93% Impervious, Inflow Depth > 2.05" for 10-yr event Inflow = 46.04 cfs @ 12.15 hrs, Volume= 3.854 af Outflow = 46.04 cfs @ 12.15 hrs, Volume= 3.854 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-yr Rainfall=5.25"Village Hill - TCB - Pre-Development Printed 1/17/2018Prepared by Microsoft Page 8HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=16.800 ac 26.79% Impervious Runoff Depth>1.97"Subcatchment EDA-1: Area in NW corner Flow Length=750' Tc=10.1 min CN=67 Runoff=32.60 cfs 2.765 af Runoff Area=22.600 ac 15.93% Impervious Runoff Depth>2.65"Subcatchment EDA-2: Area in NE corner Flow Length=680' Tc=10.4 min CN=75 Runoff=59.97 cfs 4.988 af Inflow=32.60 cfs 2.765 afReach DP-1: Control Point for existing runoff Outflow=32.60 cfs 2.765 af Inflow=59.97 cfs 4.988 afReach DP-2: Control point for existing runoff Outflow=59.97 cfs 4.988 af Type III 24-hr 25-yr Rainfall=5.25"Village Hill - TCB - Pre-Development Printed 1/17/2018Prepared by Microsoft Page 9HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Subcatchment EDA-1: Area in NW corner of existing site Area in NW corner of existing site Runoff = 32.60 cfs @ 12.15 hrs, Volume= 2.765 af, Depth> 1.97" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-yr Rainfall=5.25" Area (ac) CN Description 0.700 98 Paved parking & roofs 3.800 98 Paved parking & roofs 2.700 39 >75% Grass cover, Good, HSG A 5.000 74 >75% Grass cover, Good, HSG C 2.700 30 Woods, Good, HSG A 0.400 55 Woods, Good, HSG B 1.500 70 Woods, Good, HSG C 16.800 67 Weighted Average 12.300 73.21% Pervious Area 4.500 26.79% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.5 50 0.0250 0.11 Sheet Flow, Sheet Flow to the NW corner of property Grass: Dense n= 0.240 P2= 3.20" 0.7 130 0.0380 3.14 Shallow Concentrated Flow, Flow to NW of property Unpaved Kv= 16.1 fps 1.0 380 0.1630 6.50 Shallow Concentrated Flow, Flow to NW of property Unpaved Kv= 16.1 fps 0.9 190 0.0500 3.60 Shallow Concentrated Flow, Flow towards control point Unpaved Kv= 16.1 fps 10.1 750 Total Summary for Subcatchment EDA-2: Area in NE corner of existing site Runoff = 59.97 cfs @ 12.15 hrs, Volume= 4.988 af, Depth> 2.65" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-yr Rainfall=5.25" Area (ac) CN Description 2.800 61 >75% Grass cover, Good, HSG B 0.100 55 Woods, Good, HSG B 0.600 98 Paved parking & roofs 10.800 74 >75% Grass cover, Good, HSG C 5.300 70 Woods, Good, HSG C 3.000 98 Paved parking & roofs 22.600 75 Weighted Average 19.000 84.07% Pervious Area 3.600 15.93% Impervious Area Type III 24-hr 25-yr Rainfall=5.25"Village Hill - TCB - Pre-Development Printed 1/17/2018Prepared by Microsoft Page 10HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.9 50 0.0220 0.11 Sheet Flow, Flow to the east down dense grass hill Grass: Dense n= 0.240 P2= 3.20" 1.4 370 0.0780 4.50 Shallow Concentrated Flow, Flow to the east Unpaved Kv= 16.1 fps 1.1 260 0.0620 4.01 Shallow Concentrated Flow, Flow to control point Unpaved Kv= 16.1 fps 10.4 680 Total Summary for Reach DP-1: Control Point for existing runoff Inflow Area = 16.800 ac, 26.79% Impervious, Inflow Depth > 1.97" for 25-yr event Inflow = 32.60 cfs @ 12.15 hrs, Volume= 2.765 af Outflow = 32.60 cfs @ 12.15 hrs, Volume= 2.765 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Reach DP-2: Control point for existing runoff Inflow Area = 22.600 ac, 15.93% Impervious, Inflow Depth > 2.65" for 25-yr event Inflow = 59.97 cfs @ 12.15 hrs, Volume= 4.988 af Outflow = 59.97 cfs @ 12.15 hrs, Volume= 4.988 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=7.00"Village Hill - TCB - Pre-Development Printed 1/17/2018Prepared by Microsoft Page 11HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=16.800 ac 26.79% Impervious Runoff Depth>3.30"Subcatchment EDA-1: Area in NW corner Flow Length=750' Tc=10.1 min CN=67 Runoff=55.79 cfs 4.621 af Runoff Area=22.600 ac 15.93% Impervious Runoff Depth>4.14"Subcatchment EDA-2: Area in NE corner Flow Length=680' Tc=10.4 min CN=75 Runoff=93.89 cfs 7.801 af Inflow=55.79 cfs 4.621 afReach DP-1: Control Point for existing runoff Outflow=55.79 cfs 4.621 af Inflow=93.89 cfs 7.801 afReach DP-2: Control point for existing runoff Outflow=93.89 cfs 7.801 af Type III 24-hr 100-yr Rainfall=7.00"Village Hill - TCB - Pre-Development Printed 1/17/2018Prepared by Microsoft Page 12HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Subcatchment EDA-1: Area in NW corner of existing site Area in NW corner of existing site Runoff = 55.79 cfs @ 12.15 hrs, Volume= 4.621 af, Depth> 3.30" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=7.00" Area (ac) CN Description 0.700 98 Paved parking & roofs 3.800 98 Paved parking & roofs 2.700 39 >75% Grass cover, Good, HSG A 5.000 74 >75% Grass cover, Good, HSG C 2.700 30 Woods, Good, HSG A 0.400 55 Woods, Good, HSG B 1.500 70 Woods, Good, HSG C 16.800 67 Weighted Average 12.300 73.21% Pervious Area 4.500 26.79% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.5 50 0.0250 0.11 Sheet Flow, Sheet Flow to the NW corner of property Grass: Dense n= 0.240 P2= 3.20" 0.7 130 0.0380 3.14 Shallow Concentrated Flow, Flow to NW of property Unpaved Kv= 16.1 fps 1.0 380 0.1630 6.50 Shallow Concentrated Flow, Flow to NW of property Unpaved Kv= 16.1 fps 0.9 190 0.0500 3.60 Shallow Concentrated Flow, Flow towards control point Unpaved Kv= 16.1 fps 10.1 750 Total Summary for Subcatchment EDA-2: Area in NE corner of existing site Runoff = 93.89 cfs @ 12.15 hrs, Volume= 7.801 af, Depth> 4.14" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=7.00" Area (ac) CN Description 2.800 61 >75% Grass cover, Good, HSG B 0.100 55 Woods, Good, HSG B 0.600 98 Paved parking & roofs 10.800 74 >75% Grass cover, Good, HSG C 5.300 70 Woods, Good, HSG C 3.000 98 Paved parking & roofs 22.600 75 Weighted Average 19.000 84.07% Pervious Area 3.600 15.93% Impervious Area Type III 24-hr 100-yr Rainfall=7.00"Village Hill - TCB - Pre-Development Printed 1/17/2018Prepared by Microsoft Page 13HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.9 50 0.0220 0.11 Sheet Flow, Flow to the east down dense grass hill Grass: Dense n= 0.240 P2= 3.20" 1.4 370 0.0780 4.50 Shallow Concentrated Flow, Flow to the east Unpaved Kv= 16.1 fps 1.1 260 0.0620 4.01 Shallow Concentrated Flow, Flow to control point Unpaved Kv= 16.1 fps 10.4 680 Total Summary for Reach DP-1: Control Point for existing runoff Inflow Area = 16.800 ac, 26.79% Impervious, Inflow Depth > 3.30" for 100-yr event Inflow = 55.79 cfs @ 12.15 hrs, Volume= 4.621 af Outflow = 55.79 cfs @ 12.15 hrs, Volume= 4.621 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Reach DP-2: Control point for existing runoff Inflow Area = 22.600 ac, 15.93% Impervious, Inflow Depth > 4.14" for 100-yr event Inflow = 93.89 cfs @ 12.15 hrs, Volume= 7.801 af Outflow = 93.89 cfs @ 12.15 hrs, Volume= 7.801 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs PDA-1B Northwest Corner of Site (includes former area PDA-1A) PDA-1C Proposed Area on West Side of Site PDA-2A Northern & Eastern Edges of Site PDA-2B TCB "Lot 13A" Project PDA-2C Southeast Corner of Site PDA-2D Future Co-Housing Site DP-1 Control point for proposed runoff (area 1) DP-2 Control Point for proposed drainage S1 Drainage Swale (Upper Segment) S2 Drainage Swale (Lower Segment) P2 Basin #2 (As-Built) P3 Basin #3 (As Built) P4 Basin #4 (As Built) Routing Diagram for Village Hill - TCB - Proposed Prepared by Microsoft, Printed 1/16/2018 HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Subcat Reach Pond Link Type III 24-hr 2-yr Rainfall=3.00"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 2HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=11.918 ac 3.90% Impervious Runoff Depth>0.19"Subcatchment PDA-1B: Northwest Corner Tc=5.0 min CN=55 Runoff=0.83 cfs 0.193 af Runoff Area=10.360 ac 62.74% Impervious Runoff Depth>1.25"Subcatchment PDA-1C: Proposed Area on Tc=5.0 min CN=80 Runoff=15.00 cfs 1.078 af Runoff Area=6.172 ac 5.10% Impervious Runoff Depth>0.91"Subcatchment PDA-2A: Northern & Eastern Tc=5.0 min CN=74 Runoff=6.18 cfs 0.467 af Runoff Area=3.490 ac 49.78% Impervious Runoff Depth>1.66"Subcatchment PDA-2B: TCB "Lot 13A" Tc=5.0 min CN=86 Runoff=6.81 cfs 0.483 af Runoff Area=16.100 ac 50.45% Impervious Runoff Depth>1.59"Subcatchment PDA-2C: Southeast Corner Tc=5.0 min CN=85 Runoff=30.01 cfs 2.129 af Runoff Area=7.880 ac 26.57% Impervious Runoff Depth>1.19"Subcatchment PDA-2D: Future Co-Housing Tc=5.0 min CN=79 Runoff=10.79 cfs 0.780 af Inflow=6.07 cfs 1.044 afReach DP-1: Control point for proposed runoff (area 1) Outflow=6.07 cfs 1.044 af Inflow=11.99 cfs 3.623 afReach DP-2: Control Point for proposed drainage Outflow=11.99 cfs 3.623 af Avg. Flow Depth=0.00' Max Vel=0.00 fps Inflow=0.00 cfs 0.000 afReach S1: Drainage Swale (Upper n=0.030 L=85.0' S=0.0118 '/' Capacity=106.17 cfs Outflow=0.00 cfs 0.000 af Avg. Flow Depth=0.35' Max Vel=2.51 fps Inflow=3.63 cfs 1.978 afReach S2: Drainage Swale (Lower n=0.030 L=550.0' S=0.0144 '/' Capacity=117.31 cfs Outflow=3.62 cfs 1.971 af Peak Elev=187.68' Storage=25,588 cf Inflow=19.79 cfs 3.234 afPond P2: Basin #2 (As-Built) Outflow=7.87 cfs 3.156 af Peak Elev=209.52' Storage=8,425 cf Inflow=15.00 cfs 1.078 afPond P3: Basin #3 (As Built) Discarded=0.81 cfs 0.225 af Primary=5.24 cfs 0.851 af Outflow=6.05 cfs 1.076 af Peak Elev=201.51' Storage=41,993 cf Inflow=30.01 cfs 2.129 afPond P4: Basin #4 (As Built) Primary=3.63 cfs 1.978 af Secondary=0.00 cfs 0.000 af Tertiary=0.00 cfs 0.000 af Outflow=3.63 cfs 1.978 af Type III 24-hr 2-yr Rainfall=3.00"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 3HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Subcatchment PDA-1B: Northwest Corner of Site (includes former area PDA-1A) SWITCHED 0.25 ACRES OF IMPERVIOUS TO GRASS HYD GROUP C - THIS REPRESENTS NO DEVELOPMENT NORTHWEST OF VILLAGE HILL ROAD Runoff = 0.83 cfs @ 12.36 hrs, Volume= 0.193 af, Depth> 0.19" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-yr Rainfall=3.00" Area (ac) CN Description * 0.364 98 Pavement & Roof 3.704 30 Woods, Good, HSG A 1.987 39 >75% Grass cover, Good, HSG A 0.155 90 1/8 acre lots, 65% imp, HSG C 2.145 70 Woods, Good, HSG C 3.563 74 >75% Grass cover, Good, HSG C 11.918 55 Weighted Average 11.453 96.10% Pervious Area 0.465 3.90% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment PDA-1C: Proposed Area on West Side of Site Runoff = 15.00 cfs @ 12.08 hrs, Volume= 1.078 af, Depth> 1.25" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-yr Rainfall=3.00" Area (ac) CN Description * 6.110 98 Pavement & Roof * 0.390 98 Detention Pond 2.705 39 >75% Grass cover, Good, HSG A 1.155 74 >75% Grass cover, Good, HSG C 10.360 80 Weighted Average 3.860 37.26% Pervious Area 6.500 62.74% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Flow from Watershed Area Type III 24-hr 2-yr Rainfall=3.00"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 4HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Subcatchment PDA-2A: Northern & Eastern Edges of Site Runoff = 6.18 cfs @ 12.09 hrs, Volume= 0.467 af, Depth> 0.91" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-yr Rainfall=3.00" Area (ac) CN Description * 0.286 98 Pavement & Roof 0.029 98 Water Surface, HSG C 1.907 70 Woods, Good, HSG C 3.950 74 >75% Grass cover, Good, HSG C 6.172 74 Weighted Average 5.857 94.90% Pervious Area 0.315 5.10% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment PDA-2B: TCB "Lot 13A" Project Runoff = 6.81 cfs @ 12.08 hrs, Volume= 0.483 af, Depth> 1.66" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-yr Rainfall=3.00" Area (ac) CN Description * 1.386 98 Pavement & Roof * 0.068 98 Pond/Rain Garden 0.028 61 >75% Grass cover, Good, HSG B 0.436 90 1/8 acre lots, 65% imp, HSG C 1.572 74 >75% Grass cover, Good, HSG C 3.490 86 Weighted Average 1.753 50.22% Pervious Area 1.737 49.78% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment PDA-2C: Southeast Corner of Site Runoff = 30.01 cfs @ 12.08 hrs, Volume= 2.129 af, Depth> 1.59" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-yr Rainfall=3.00" Type III 24-hr 2-yr Rainfall=3.00"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 5HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Area (ac) CN Description 7.050 98 Paved parking & roofs * 0.785 98 Detention Pond/Rain Garden 0.443 90 1/8 acre lots, 65% imp, HSG C 1.214 61 >75% Grass cover, Good, HSG B 6.608 74 >75% Grass cover, Good, HSG C 16.100 85 Weighted Average 7.977 49.55% Pervious Area 8.123 50.45% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment PDA-2D: Future Co-Housing Site Runoff = 10.79 cfs @ 12.08 hrs, Volume= 0.780 af, Depth> 1.19" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-yr Rainfall=3.00" Area (ac) CN Description * 1.748 98 Pavement & Roof * 0.175 98 Pavement & Roof * 0.171 98 Detention Basin 0.969 61 >75% Grass cover, Good, HSG B 0.410 70 Woods, Good, HSG C 4.407 74 >75% Grass cover, Good, HSG C 7.880 79 Weighted Average 5.786 73.43% Pervious Area 2.094 26.57% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Reach DP-1: Control point for proposed runoff (area 1) Inflow Area = 22.278 ac, 31.26% Impervious, Inflow Depth > 0.56" for 2-yr event Inflow = 6.07 cfs @ 12.35 hrs, Volume= 1.044 af Outflow = 6.07 cfs @ 12.35 hrs, Volume= 1.044 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-yr Rainfall=3.00"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 6HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Reach DP-2: Control Point for proposed drainage Inflow Area = 33.642 ac, 36.47% Impervious, Inflow Depth > 1.29" for 2-yr event Inflow = 11.99 cfs @ 12.11 hrs, Volume= 3.623 af Outflow = 11.99 cfs @ 12.11 hrs, Volume= 3.623 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Reach S1: Drainage Swale (Upper Segment) Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Outflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 0.00 fps, Min. Travel Time= 0.0 min Avg. Velocity = 0.00 fps, Avg. Travel Time= 0.0 min Peak Storage= 0 cf @ 0.00 hrs Average Depth at Peak Storage= 0.00' Bank-Full Depth= 2.00' Flow Area= 18.0 sf, Capacity= 106.17 cfs 3.00' x 2.00' deep channel, n= 0.030 Earth, grassed & winding Side Slope Z-value= 3.0 '/' Top Width= 15.00' Length= 85.0' Slope= 0.0118 '/' Inlet Invert= 202.00', Outlet Invert= 201.00' ‡ Summary for Reach S2: Drainage Swale (Lower Segment) Inflow Area = 16.100 ac, 50.45% Impervious, Inflow Depth > 1.47" for 2-yr event Inflow = 3.63 cfs @ 12.80 hrs, Volume= 1.978 af Outflow = 3.62 cfs @ 12.91 hrs, Volume= 1.971 af, Atten= 0%, Lag= 6.3 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 2.51 fps, Min. Travel Time= 3.6 min Avg. Velocity = 1.78 fps, Avg. Travel Time= 5.2 min Peak Storage= 794 cf @ 12.85 hrs Average Depth at Peak Storage= 0.35' Bank-Full Depth= 2.00' Flow Area= 18.0 sf, Capacity= 117.31 cfs 3.00' x 2.00' deep channel, n= 0.030 Earth, grassed & winding Side Slope Z-value= 3.0 '/' Top Width= 15.00' Length= 550.0' Slope= 0.0144 '/' Inlet Invert= 197.90', Outlet Invert= 190.00' Type III 24-hr 2-yr Rainfall=3.00"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 7HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC ‡ Summary for Pond P2: Basin #2 (As-Built) Inflow Area = 27.470 ac, 43.52% Impervious, Inflow Depth > 1.41" for 2-yr event Inflow = 19.79 cfs @ 12.09 hrs, Volume= 3.234 af Outflow = 7.87 cfs @ 12.49 hrs, Volume= 3.156 af, Atten= 60%, Lag= 24.3 min Primary = 7.87 cfs @ 12.49 hrs, Volume= 3.156 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Starting Elev= 186.10' Surf.Area= 11,124 sf Storage= 6,465 cf Peak Elev= 187.68' @ 12.49 hrs Surf.Area= 13,023 sf Storage= 25,588 cf (19,123 cf above start) Plug-Flow detention time= 73.9 min calculated for 3.001 af (93% of inflow) Center-of-Mass det. time= 30.2 min ( 938.7 - 908.5 ) Volume Invert Avail.Storage Storage Description #1 185.50' 97,586 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 185.50 10,431 0 0 186.00 11,004 5,359 5,359 188.00 13,402 24,406 29,765 190.00 16,648 30,050 59,815 192.00 21,123 37,771 97,586 Device Routing Invert Outlet Devices #1 Primary 186.08'36.0" Round Culvert L= 212.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 186.08' / 181.31' S= 0.0225 '/' Cc= 0.900 n= 0.013, Flow Area= 7.07 sf #2 Device 1 186.10'12.0" Vert. Orifice/Grate C= 0.600 #3 Device 1 186.10'12.0" Vert. Orifice/Grate C= 0.600 #4 Device 1 188.00'6.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 #5 Primary 191.50'Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Head (feet) 0.00 0.50 1.00 Width (feet) 5.00 8.00 57.00 Type III 24-hr 2-yr Rainfall=3.00"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 8HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Primary OutFlow Max=7.87 cfs @ 12.49 hrs HW=187.68' (Free Discharge) 1=Culvert (Passes 7.87 cfs of 16.57 cfs potential flow) 2=Orifice/Grate (Orifice Controls 3.94 cfs @ 5.01 fps) 3=Orifice/Grate (Orifice Controls 3.94 cfs @ 5.01 fps) 4=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) 5=Custom Weir/Orifice ( Controls 0.00 cfs) Summary for Pond P3: Basin #3 (As Built) Inflow Area = 10.360 ac, 62.74% Impervious, Inflow Depth > 1.25" for 2-yr event Inflow = 15.00 cfs @ 12.08 hrs, Volume= 1.078 af Outflow = 6.05 cfs @ 12.35 hrs, Volume= 1.076 af, Atten= 60%, Lag= 15.8 min Discarded = 0.81 cfs @ 12.35 hrs, Volume= 0.225 af Primary = 5.24 cfs @ 12.35 hrs, Volume= 0.851 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs / 2 Peak Elev= 209.52' @ 12.35 hrs Surf.Area= 5,825 sf Storage= 8,425 cf Plug-Flow detention time= 11.6 min calculated for 1.074 af (100% of inflow) Center-of-Mass det. time= 10.6 min ( 855.3 - 844.7 ) Volume Invert Avail.Storage Storage Description #1 207.10' 67,302 cf Custom Stage Data (Conic) Listed below Elevation Surf.Area Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (cubic-feet) (cubic-feet) (sq-ft) 207.10 0 0 0 0 207.50 1,512 202 202 1,512 208.00 3,206 1,153 1,355 3,208 209.00 4,988 4,064 5,419 5,005 210.00 6,596 5,773 11,193 6,635 211.00 8,446 7,502 18,694 8,510 212.00 10,503 9,456 28,150 10,596 213.00 12,662 11,566 39,716 12,788 214.00 15,015 13,822 53,538 15,178 214.85 17,400 13,764 67,302 17,593 Device Routing Invert Outlet Devices #1 Primary 207.00'30.0" Round Culvert L= 65.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 207.00' / 206.65' S= 0.0054 '/' Cc= 0.900 n= 0.011 Concrete pipe, straight & clean, Flow Area= 4.91 sf #2 Device 1 207.10'12.0" Vert. Orifice/Grate C= 0.600 #3 Device 1 209.75'12.0" Vert. Orifice/Grate C= 0.600 #4 Device 1 211.30'10.0" Vert. Orifice/Grate X 2.00 C= 0.600 #5 Device 1 213.15'11.5' long x 0.5' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 Coef. (English) 2.80 2.92 3.08 3.30 3.32 #6 Primary 213.85'15.0' long x 10.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Type III 24-hr 2-yr Rainfall=3.00"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 9HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64 #7 Discarded 207.10'6.000 in/hr Exfiltration over Wetted area Discarded OutFlow Max=0.81 cfs @ 12.35 hrs HW=209.52' (Free Discharge) 7=Exfiltration (Exfiltration Controls 0.81 cfs) Primary OutFlow Max=5.24 cfs @ 12.35 hrs HW=209.52' (Free Discharge) 1=Culvert (Passes 5.24 cfs of 23.35 cfs potential flow) 2=Orifice/Grate (Orifice Controls 5.24 cfs @ 6.67 fps) 3=Orifice/Grate ( Controls 0.00 cfs) 4=Orifice/Grate ( Controls 0.00 cfs) 5=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) 6=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond P4: Basin #4 (As Built) Inflow Area = 16.100 ac, 50.45% Impervious, Inflow Depth > 1.59" for 2-yr event Inflow = 30.01 cfs @ 12.08 hrs, Volume= 2.129 af Outflow = 3.63 cfs @ 12.80 hrs, Volume= 1.978 af, Atten= 88%, Lag= 43.5 min Primary = 3.63 cfs @ 12.80 hrs, Volume= 1.978 af Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Tertiary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 201.51' @ 12.80 hrs Surf.Area= 22,799 sf Storage= 41,993 cf Plug-Flow detention time= 155.7 min calculated for 1.974 af (93% of inflow) Center-of-Mass det. time= 119.2 min ( 946.8 - 827.6 ) Volume Invert Avail.Storage Storage Description #1 199.30' 108,414 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 199.30 14,500 0 0 200.00 17,810 11,308 11,308 202.00 24,412 42,222 53,530 204.00 30,472 54,884 108,414 Device Routing Invert Outlet Devices #1 Primary 199.37'12.0" Round Culvert L= 194.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 199.37' / 198.00' S= 0.0071 '/' Cc= 0.900 n= 0.013 Concrete pipe, bends & connections, Flow Area= 0.79 sf #2 Secondary 202.00'8.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 #3 Tertiary 203.50'15.0' long x 10.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Type III 24-hr 2-yr Rainfall=3.00"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 10HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64 Primary OutFlow Max=3.63 cfs @ 12.80 hrs HW=201.51' (Free Discharge) 1=Culvert (Barrel Controls 3.63 cfs @ 4.62 fps) Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=199.30' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Tertiary OutFlow Max=0.00 cfs @ 0.00 hrs HW=199.30' (Free Discharge) 3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type III 24-hr 10-yr Rainfall=4.50"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 11HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=11.918 ac 3.90% Impervious Runoff Depth>0.74"Subcatchment PDA-1B: Northwest Corner Tc=5.0 min CN=55 Runoff=7.67 cfs 0.736 af Runoff Area=10.360 ac 62.74% Impervious Runoff Depth>2.46"Subcatchment PDA-1C: Proposed Area on Tc=5.0 min CN=80 Runoff=29.93 cfs 2.124 af Runoff Area=6.172 ac 5.10% Impervious Runoff Depth>1.97"Subcatchment PDA-2A: Northern & Eastern Tc=5.0 min CN=74 Runoff=14.16 cfs 1.014 af Runoff Area=3.490 ac 49.78% Impervious Runoff Depth>3.00"Subcatchment PDA-2B: TCB "Lot 13A" Tc=5.0 min CN=86 Runoff=12.24 cfs 0.873 af Runoff Area=16.100 ac 50.45% Impervious Runoff Depth>2.91"Subcatchment PDA-2C: Southeast Corner Tc=5.0 min CN=85 Runoff=54.88 cfs 3.901 af Runoff Area=7.880 ac 26.57% Impervious Runoff Depth>2.37"Subcatchment PDA-2D: Future Co-Housing Tc=5.0 min CN=79 Runoff=21.97 cfs 1.559 af Inflow=16.22 cfs 2.497 afReach DP-1: Control point for proposed runoff (area 1) Outflow=16.22 cfs 2.497 af Inflow=27.47 cfs 7.039 afReach DP-2: Control Point for proposed drainage Outflow=27.47 cfs 7.039 af Avg. Flow Depth=0.68' Max Vel=3.25 fps Inflow=11.20 cfs 0.683 afReach S1: Drainage Swale (Upper n=0.030 L=85.0' S=0.0118 '/' Capacity=106.17 cfs Outflow=11.17 cfs 0.683 af Avg. Flow Depth=0.76' Max Vel=3.82 fps Inflow=15.53 cfs 3.706 afReach S2: Drainage Swale (Lower n=0.030 L=550.0' S=0.0144 '/' Capacity=117.31 cfs Outflow=15.41 cfs 3.697 af Peak Elev=188.79' Storage=40,916 cf Inflow=37.50 cfs 6.129 afPond P2: Basin #2 (As-Built) Outflow=23.29 cfs 6.025 af Peak Elev=211.11' Storage=19,734 cf Inflow=29.93 cfs 2.124 afPond P3: Basin #3 (As Built) Discarded=1.21 cfs 0.361 af Primary=10.59 cfs 1.760 af Outflow=11.80 cfs 2.121 af Peak Elev=202.63' Storage=69,640 cf Inflow=54.88 cfs 3.901 afPond P4: Basin #4 (As Built) Primary=4.36 cfs 3.023 af Secondary=11.20 cfs 0.683 af Tertiary=0.00 cfs 0.000 af Outflow=15.56 cfs 3.706 af Type III 24-hr 10-yr Rainfall=4.50"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 12HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Subcatchment PDA-1B: Northwest Corner of Site (includes former area PDA-1A) SWITCHED 0.25 ACRES OF IMPERVIOUS TO GRASS HYD GROUP C - THIS REPRESENTS NO DEVELOPMENT NORTHWEST OF VILLAGE HILL ROAD Runoff = 7.67 cfs @ 12.11 hrs, Volume= 0.736 af, Depth> 0.74" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.50" Area (ac) CN Description * 0.364 98 Pavement & Roof 3.704 30 Woods, Good, HSG A 1.987 39 >75% Grass cover, Good, HSG A 0.155 90 1/8 acre lots, 65% imp, HSG C 2.145 70 Woods, Good, HSG C 3.563 74 >75% Grass cover, Good, HSG C 11.918 55 Weighted Average 11.453 96.10% Pervious Area 0.465 3.90% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment PDA-1C: Proposed Area on West Side of Site Runoff = 29.93 cfs @ 12.08 hrs, Volume= 2.124 af, Depth> 2.46" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.50" Area (ac) CN Description * 6.110 98 Pavement & Roof * 0.390 98 Detention Pond 2.705 39 >75% Grass cover, Good, HSG A 1.155 74 >75% Grass cover, Good, HSG C 10.360 80 Weighted Average 3.860 37.26% Pervious Area 6.500 62.74% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Flow from Watershed Area Type III 24-hr 10-yr Rainfall=4.50"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 13HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Subcatchment PDA-2A: Northern & Eastern Edges of Site Runoff = 14.16 cfs @ 12.08 hrs, Volume= 1.014 af, Depth> 1.97" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.50" Area (ac) CN Description * 0.286 98 Pavement & Roof 0.029 98 Water Surface, HSG C 1.907 70 Woods, Good, HSG C 3.950 74 >75% Grass cover, Good, HSG C 6.172 74 Weighted Average 5.857 94.90% Pervious Area 0.315 5.10% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment PDA-2B: TCB "Lot 13A" Project Runoff = 12.24 cfs @ 12.07 hrs, Volume= 0.873 af, Depth> 3.00" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.50" Area (ac) CN Description * 1.386 98 Pavement & Roof * 0.068 98 Pond/Rain Garden 0.028 61 >75% Grass cover, Good, HSG B 0.436 90 1/8 acre lots, 65% imp, HSG C 1.572 74 >75% Grass cover, Good, HSG C 3.490 86 Weighted Average 1.753 50.22% Pervious Area 1.737 49.78% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment PDA-2C: Southeast Corner of Site Runoff = 54.88 cfs @ 12.07 hrs, Volume= 3.901 af, Depth> 2.91" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.50" Type III 24-hr 10-yr Rainfall=4.50"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 14HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Area (ac) CN Description 7.050 98 Paved parking & roofs * 0.785 98 Detention Pond/Rain Garden 0.443 90 1/8 acre lots, 65% imp, HSG C 1.214 61 >75% Grass cover, Good, HSG B 6.608 74 >75% Grass cover, Good, HSG C 16.100 85 Weighted Average 7.977 49.55% Pervious Area 8.123 50.45% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment PDA-2D: Future Co-Housing Site Runoff = 21.97 cfs @ 12.08 hrs, Volume= 1.559 af, Depth> 2.37" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.50" Area (ac) CN Description * 1.748 98 Pavement & Roof * 0.175 98 Pavement & Roof * 0.171 98 Detention Basin 0.969 61 >75% Grass cover, Good, HSG B 0.410 70 Woods, Good, HSG C 4.407 74 >75% Grass cover, Good, HSG C 7.880 79 Weighted Average 5.786 73.43% Pervious Area 2.094 26.57% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Reach DP-1: Control point for proposed runoff (area 1) Inflow Area = 22.278 ac, 31.26% Impervious, Inflow Depth > 1.34" for 10-yr event Inflow = 16.22 cfs @ 12.15 hrs, Volume= 2.497 af Outflow = 16.22 cfs @ 12.15 hrs, Volume= 2.497 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.50"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 15HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Reach DP-2: Control Point for proposed drainage Inflow Area = 33.642 ac, 36.47% Impervious, Inflow Depth > 2.51" for 10-yr event Inflow = 27.47 cfs @ 12.40 hrs, Volume= 7.039 af Outflow = 27.47 cfs @ 12.40 hrs, Volume= 7.039 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Reach S1: Drainage Swale (Upper Segment) Inflow = 11.20 cfs @ 12.43 hrs, Volume= 0.683 af Outflow = 11.17 cfs @ 12.44 hrs, Volume= 0.683 af, Atten= 0%, Lag= 0.9 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 3.25 fps, Min. Travel Time= 0.4 min Avg. Velocity = 1.79 fps, Avg. Travel Time= 0.8 min Peak Storage= 293 cf @ 12.43 hrs Average Depth at Peak Storage= 0.68' Bank-Full Depth= 2.00' Flow Area= 18.0 sf, Capacity= 106.17 cfs 3.00' x 2.00' deep channel, n= 0.030 Earth, grassed & winding Side Slope Z-value= 3.0 '/' Top Width= 15.00' Length= 85.0' Slope= 0.0118 '/' Inlet Invert= 202.00', Outlet Invert= 201.00' ‡ Summary for Reach S2: Drainage Swale (Lower Segment) Inflow Area = 16.100 ac, 50.45% Impervious, Inflow Depth > 2.76" for 10-yr event Inflow = 15.53 cfs @ 12.44 hrs, Volume= 3.706 af Outflow = 15.41 cfs @ 12.51 hrs, Volume= 3.697 af, Atten= 1%, Lag= 4.3 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 3.82 fps, Min. Travel Time= 2.4 min Avg. Velocity = 2.08 fps, Avg. Travel Time= 4.4 min Peak Storage= 2,224 cf @ 12.47 hrs Average Depth at Peak Storage= 0.76' Bank-Full Depth= 2.00' Flow Area= 18.0 sf, Capacity= 117.31 cfs 3.00' x 2.00' deep channel, n= 0.030 Earth, grassed & winding Side Slope Z-value= 3.0 '/' Top Width= 15.00' Length= 550.0' Slope= 0.0144 '/' Inlet Invert= 197.90', Outlet Invert= 190.00' Type III 24-hr 10-yr Rainfall=4.50"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 16HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC ‡ Summary for Pond P2: Basin #2 (As-Built) Inflow Area = 27.470 ac, 43.52% Impervious, Inflow Depth > 2.68" for 10-yr event Inflow = 37.50 cfs @ 12.08 hrs, Volume= 6.129 af Outflow = 23.29 cfs @ 12.49 hrs, Volume= 6.025 af, Atten= 38%, Lag= 24.6 min Primary = 23.29 cfs @ 12.49 hrs, Volume= 6.025 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Starting Elev= 186.10' Surf.Area= 11,124 sf Storage= 6,465 cf Peak Elev= 188.79' @ 12.49 hrs Surf.Area= 14,691 sf Storage= 40,916 cf (34,451 cf above start) Plug-Flow detention time= 56.2 min calculated for 5.877 af (96% of inflow) Center-of-Mass det. time= 28.2 min ( 919.0 - 890.7 ) Volume Invert Avail.Storage Storage Description #1 185.50' 97,586 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 185.50 10,431 0 0 186.00 11,004 5,359 5,359 188.00 13,402 24,406 29,765 190.00 16,648 30,050 59,815 192.00 21,123 37,771 97,586 Device Routing Invert Outlet Devices #1 Primary 186.08'36.0" Round Culvert L= 212.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 186.08' / 181.31' S= 0.0225 '/' Cc= 0.900 n= 0.013, Flow Area= 7.07 sf #2 Device 1 186.10'12.0" Vert. Orifice/Grate C= 0.600 #3 Device 1 186.10'12.0" Vert. Orifice/Grate C= 0.600 #4 Device 1 188.00'6.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 #5 Primary 191.50'Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Head (feet) 0.00 0.50 1.00 Width (feet) 5.00 8.00 57.00 Type III 24-hr 10-yr Rainfall=4.50"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 17HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Primary OutFlow Max=23.24 cfs @ 12.49 hrs HW=188.79' (Free Discharge) 1=Culvert (Passes 23.24 cfs of 37.70 cfs potential flow) 2=Orifice/Grate (Orifice Controls 5.60 cfs @ 7.13 fps) 3=Orifice/Grate (Orifice Controls 5.60 cfs @ 7.13 fps) 4=Broad-Crested Rectangular Weir (Weir Controls 12.04 cfs @ 2.53 fps) 5=Custom Weir/Orifice ( Controls 0.00 cfs) Summary for Pond P3: Basin #3 (As Built) Inflow Area = 10.360 ac, 62.74% Impervious, Inflow Depth > 2.46" for 10-yr event Inflow = 29.93 cfs @ 12.08 hrs, Volume= 2.124 af Outflow = 11.80 cfs @ 12.33 hrs, Volume= 2.121 af, Atten= 61%, Lag= 15.0 min Discarded = 1.21 cfs @ 12.33 hrs, Volume= 0.361 af Primary = 10.59 cfs @ 12.33 hrs, Volume= 1.760 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs / 2 Peak Elev= 211.11' @ 12.33 hrs Surf.Area= 8,672 sf Storage= 19,734 cf Plug-Flow detention time= 16.2 min calculated for 2.116 af (100% of inflow) Center-of-Mass det. time= 15.4 min ( 840.5 - 825.1 ) Volume Invert Avail.Storage Storage Description #1 207.10' 67,302 cf Custom Stage Data (Conic) Listed below Elevation Surf.Area Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (cubic-feet) (cubic-feet) (sq-ft) 207.10 0 0 0 0 207.50 1,512 202 202 1,512 208.00 3,206 1,153 1,355 3,208 209.00 4,988 4,064 5,419 5,005 210.00 6,596 5,773 11,193 6,635 211.00 8,446 7,502 18,694 8,510 212.00 10,503 9,456 28,150 10,596 213.00 12,662 11,566 39,716 12,788 214.00 15,015 13,822 53,538 15,178 214.85 17,400 13,764 67,302 17,593 Device Routing Invert Outlet Devices #1 Primary 207.00'30.0" Round Culvert L= 65.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 207.00' / 206.65' S= 0.0054 '/' Cc= 0.900 n= 0.011 Concrete pipe, straight & clean, Flow Area= 4.91 sf #2 Device 1 207.10'12.0" Vert. Orifice/Grate C= 0.600 #3 Device 1 209.75'12.0" Vert. Orifice/Grate C= 0.600 #4 Device 1 211.30'10.0" Vert. Orifice/Grate X 2.00 C= 0.600 #5 Device 1 213.15'11.5' long x 0.5' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 Coef. (English) 2.80 2.92 3.08 3.30 3.32 #6 Primary 213.85'15.0' long x 10.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Type III 24-hr 10-yr Rainfall=4.50"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 18HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64 #7 Discarded 207.10'6.000 in/hr Exfiltration over Wetted area Discarded OutFlow Max=1.21 cfs @ 12.33 hrs HW=211.11' (Free Discharge) 7=Exfiltration (Exfiltration Controls 1.21 cfs) Primary OutFlow Max=10.58 cfs @ 12.33 hrs HW=211.11' (Free Discharge) 1=Culvert (Passes 10.58 cfs of 39.65 cfs potential flow) 2=Orifice/Grate (Orifice Controls 7.08 cfs @ 9.02 fps) 3=Orifice/Grate (Orifice Controls 3.50 cfs @ 4.46 fps) 4=Orifice/Grate ( Controls 0.00 cfs) 5=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) 6=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond P4: Basin #4 (As Built) Inflow Area = 16.100 ac, 50.45% Impervious, Inflow Depth > 2.91" for 10-yr event Inflow = 54.88 cfs @ 12.07 hrs, Volume= 3.901 af Outflow = 15.56 cfs @ 12.43 hrs, Volume= 3.706 af, Atten= 72%, Lag= 21.1 min Primary = 4.36 cfs @ 12.43 hrs, Volume= 3.023 af Secondary = 11.20 cfs @ 12.43 hrs, Volume= 0.683 af Tertiary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 202.63' @ 12.43 hrs Surf.Area= 26,336 sf Storage= 69,640 cf Plug-Flow detention time= 148.9 min calculated for 3.698 af (95% of inflow) Center-of-Mass det. time= 121.6 min ( 932.0 - 810.4 ) Volume Invert Avail.Storage Storage Description #1 199.30' 108,414 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 199.30 14,500 0 0 200.00 17,810 11,308 11,308 202.00 24,412 42,222 53,530 204.00 30,472 54,884 108,414 Device Routing Invert Outlet Devices #1 Primary 199.37'12.0" Round Culvert L= 194.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 199.37' / 198.00' S= 0.0071 '/' Cc= 0.900 n= 0.013 Concrete pipe, bends & connections, Flow Area= 0.79 sf #2 Secondary 202.00'8.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 #3 Tertiary 203.50'15.0' long x 10.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Type III 24-hr 10-yr Rainfall=4.50"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 19HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64 Primary OutFlow Max=4.36 cfs @ 12.43 hrs HW=202.63' (Free Discharge) 1=Culvert (Barrel Controls 4.36 cfs @ 5.55 fps) Secondary OutFlow Max=11.14 cfs @ 12.43 hrs HW=202.63' (Free Discharge) 2=Broad-Crested Rectangular Weir (Weir Controls 11.14 cfs @ 2.20 fps) Tertiary OutFlow Max=0.00 cfs @ 0.00 hrs HW=199.30' (Free Discharge) 3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type III 24-hr 25-yr Rainfall=5.25"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 20HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=11.918 ac 3.90% Impervious Runoff Depth>1.11"Subcatchment PDA-1B: Northwest Corner Tc=5.0 min CN=55 Runoff=13.02 cfs 1.098 af Runoff Area=10.360 ac 62.74% Impervious Runoff Depth>3.11"Subcatchment PDA-1C: Proposed Area on Tc=5.0 min CN=80 Runoff=37.76 cfs 2.685 af Runoff Area=6.172 ac 5.10% Impervious Runoff Depth>2.56"Subcatchment PDA-2A: Northern & Eastern Tc=5.0 min CN=74 Runoff=18.54 cfs 1.318 af Runoff Area=3.490 ac 49.78% Impervious Runoff Depth>3.70"Subcatchment PDA-2B: TCB "Lot 13A" Tc=5.0 min CN=86 Runoff=14.98 cfs 1.076 af Runoff Area=16.100 ac 50.45% Impervious Runoff Depth>3.60"Subcatchment PDA-2C: Southeast Corner Tc=5.0 min CN=85 Runoff=67.48 cfs 4.827 af Runoff Area=7.880 ac 26.57% Impervious Runoff Depth>3.02"Subcatchment PDA-2D: Future Co-Housing Tc=5.0 min CN=79 Runoff=27.89 cfs 1.981 af Inflow=23.71 cfs 3.356 afReach DP-1: Control point for proposed runoff (area 1) Outflow=23.71 cfs 3.356 af Inflow=44.50 cfs 8.860 afReach DP-2: Control Point for proposed drainage Outflow=44.50 cfs 8.860 af Avg. Flow Depth=0.94' Max Vel=3.87 fps Inflow=21.24 cfs 1.272 afReach S1: Drainage Swale (Upper n=0.030 L=85.0' S=0.0118 '/' Capacity=106.17 cfs Outflow=21.19 cfs 1.272 af Avg. Flow Depth=0.98' Max Vel=4.38 fps Inflow=25.73 cfs 4.612 afReach S2: Drainage Swale (Lower n=0.030 L=550.0' S=0.0144 '/' Capacity=117.31 cfs Outflow=25.50 cfs 4.602 af Peak Elev=189.25' Storage=47,716 cf Inflow=46.44 cfs 7.658 afPond P2: Basin #2 (As-Built) Outflow=38.23 cfs 7.542 af Peak Elev=211.76' Storage=25,854 cf Inflow=37.76 cfs 2.685 afPond P3: Basin #3 (As Built) Discarded=1.40 cfs 0.424 af Primary=13.76 cfs 2.258 af Outflow=15.17 cfs 2.682 af Peak Elev=202.93' Storage=77,671 cf Inflow=67.48 cfs 4.827 afPond P4: Basin #4 (As Built) Primary=4.54 cfs 3.339 af Secondary=21.24 cfs 1.272 af Tertiary=0.00 cfs 0.000 af Outflow=25.78 cfs 4.612 af Type III 24-hr 25-yr Rainfall=5.25"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 21HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Subcatchment PDA-1B: Northwest Corner of Site (includes former area PDA-1A) SWITCHED 0.25 ACRES OF IMPERVIOUS TO GRASS HYD GROUP C - THIS REPRESENTS NO DEVELOPMENT NORTHWEST OF VILLAGE HILL ROAD Runoff = 13.02 cfs @ 12.10 hrs, Volume= 1.098 af, Depth> 1.11" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-yr Rainfall=5.25" Area (ac) CN Description * 0.364 98 Pavement & Roof 3.704 30 Woods, Good, HSG A 1.987 39 >75% Grass cover, Good, HSG A 0.155 90 1/8 acre lots, 65% imp, HSG C 2.145 70 Woods, Good, HSG C 3.563 74 >75% Grass cover, Good, HSG C 11.918 55 Weighted Average 11.453 96.10% Pervious Area 0.465 3.90% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment PDA-1C: Proposed Area on West Side of Site Runoff = 37.76 cfs @ 12.08 hrs, Volume= 2.685 af, Depth> 3.11" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-yr Rainfall=5.25" Area (ac) CN Description * 6.110 98 Pavement & Roof * 0.390 98 Detention Pond 2.705 39 >75% Grass cover, Good, HSG A 1.155 74 >75% Grass cover, Good, HSG C 10.360 80 Weighted Average 3.860 37.26% Pervious Area 6.500 62.74% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Flow from Watershed Area Type III 24-hr 25-yr Rainfall=5.25"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 22HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Subcatchment PDA-2A: Northern & Eastern Edges of Site Runoff = 18.54 cfs @ 12.08 hrs, Volume= 1.318 af, Depth> 2.56" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-yr Rainfall=5.25" Area (ac) CN Description * 0.286 98 Pavement & Roof 0.029 98 Water Surface, HSG C 1.907 70 Woods, Good, HSG C 3.950 74 >75% Grass cover, Good, HSG C 6.172 74 Weighted Average 5.857 94.90% Pervious Area 0.315 5.10% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment PDA-2B: TCB "Lot 13A" Project Runoff = 14.98 cfs @ 12.07 hrs, Volume= 1.076 af, Depth> 3.70" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-yr Rainfall=5.25" Area (ac) CN Description * 1.386 98 Pavement & Roof * 0.068 98 Pond/Rain Garden 0.028 61 >75% Grass cover, Good, HSG B 0.436 90 1/8 acre lots, 65% imp, HSG C 1.572 74 >75% Grass cover, Good, HSG C 3.490 86 Weighted Average 1.753 50.22% Pervious Area 1.737 49.78% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment PDA-2C: Southeast Corner of Site Runoff = 67.48 cfs @ 12.07 hrs, Volume= 4.827 af, Depth> 3.60" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-yr Rainfall=5.25" Type III 24-hr 25-yr Rainfall=5.25"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 23HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Area (ac) CN Description 7.050 98 Paved parking & roofs * 0.785 98 Detention Pond/Rain Garden 0.443 90 1/8 acre lots, 65% imp, HSG C 1.214 61 >75% Grass cover, Good, HSG B 6.608 74 >75% Grass cover, Good, HSG C 16.100 85 Weighted Average 7.977 49.55% Pervious Area 8.123 50.45% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment PDA-2D: Future Co-Housing Site Runoff = 27.89 cfs @ 12.08 hrs, Volume= 1.981 af, Depth> 3.02" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-yr Rainfall=5.25" Area (ac) CN Description * 1.748 98 Pavement & Roof * 0.175 98 Pavement & Roof * 0.171 98 Detention Basin 0.969 61 >75% Grass cover, Good, HSG B 0.410 70 Woods, Good, HSG C 4.407 74 >75% Grass cover, Good, HSG C 7.880 79 Weighted Average 5.786 73.43% Pervious Area 2.094 26.57% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Reach DP-1: Control point for proposed runoff (area 1) Inflow Area = 22.278 ac, 31.26% Impervious, Inflow Depth > 1.81" for 25-yr event Inflow = 23.71 cfs @ 12.11 hrs, Volume= 3.356 af Outflow = 23.71 cfs @ 12.11 hrs, Volume= 3.356 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-yr Rainfall=5.25"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 24HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Reach DP-2: Control Point for proposed drainage Inflow Area = 33.642 ac, 36.47% Impervious, Inflow Depth > 3.16" for 25-yr event Inflow = 44.50 cfs @ 12.37 hrs, Volume= 8.860 af Outflow = 44.50 cfs @ 12.37 hrs, Volume= 8.860 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Reach S1: Drainage Swale (Upper Segment) Inflow = 21.24 cfs @ 12.32 hrs, Volume= 1.272 af Outflow = 21.19 cfs @ 12.33 hrs, Volume= 1.272 af, Atten= 0%, Lag= 1.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 3.87 fps, Min. Travel Time= 0.4 min Avg. Velocity = 1.96 fps, Avg. Travel Time= 0.7 min Peak Storage= 466 cf @ 12.33 hrs Average Depth at Peak Storage= 0.94' Bank-Full Depth= 2.00' Flow Area= 18.0 sf, Capacity= 106.17 cfs 3.00' x 2.00' deep channel, n= 0.030 Earth, grassed & winding Side Slope Z-value= 3.0 '/' Top Width= 15.00' Length= 85.0' Slope= 0.0118 '/' Inlet Invert= 202.00', Outlet Invert= 201.00' ‡ Summary for Reach S2: Drainage Swale (Lower Segment) Inflow Area = 16.100 ac, 50.45% Impervious, Inflow Depth > 3.44" for 25-yr event Inflow = 25.73 cfs @ 12.33 hrs, Volume= 4.612 af Outflow = 25.50 cfs @ 12.40 hrs, Volume= 4.602 af, Atten= 1%, Lag= 3.7 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 4.38 fps, Min. Travel Time= 2.1 min Avg. Velocity = 2.16 fps, Avg. Travel Time= 4.3 min Peak Storage= 3,213 cf @ 12.36 hrs Average Depth at Peak Storage= 0.98' Bank-Full Depth= 2.00' Flow Area= 18.0 sf, Capacity= 117.31 cfs 3.00' x 2.00' deep channel, n= 0.030 Earth, grassed & winding Side Slope Z-value= 3.0 '/' Top Width= 15.00' Length= 550.0' Slope= 0.0144 '/' Inlet Invert= 197.90', Outlet Invert= 190.00' Type III 24-hr 25-yr Rainfall=5.25"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 25HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC ‡ Summary for Pond P2: Basin #2 (As-Built) Inflow Area = 27.470 ac, 43.52% Impervious, Inflow Depth > 3.35" for 25-yr event Inflow = 46.44 cfs @ 12.08 hrs, Volume= 7.658 af Outflow = 38.23 cfs @ 12.42 hrs, Volume= 7.542 af, Atten= 18%, Lag= 20.2 min Primary = 38.23 cfs @ 12.42 hrs, Volume= 7.542 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Starting Elev= 186.10' Surf.Area= 11,124 sf Storage= 6,465 cf Peak Elev= 189.25' @ 12.42 hrs Surf.Area= 15,423 sf Storage= 47,716 cf (41,250 cf above start) Plug-Flow detention time= 50.0 min calculated for 7.393 af (97% of inflow) Center-of-Mass det. time= 25.7 min ( 902.4 - 876.7 ) Volume Invert Avail.Storage Storage Description #1 185.50' 97,586 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 185.50 10,431 0 0 186.00 11,004 5,359 5,359 188.00 13,402 24,406 29,765 190.00 16,648 30,050 59,815 192.00 21,123 37,771 97,586 Device Routing Invert Outlet Devices #1 Primary 186.08'36.0" Round Culvert L= 212.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 186.08' / 181.31' S= 0.0225 '/' Cc= 0.900 n= 0.013, Flow Area= 7.07 sf #2 Device 1 186.10'12.0" Vert. Orifice/Grate C= 0.600 #3 Device 1 186.10'12.0" Vert. Orifice/Grate C= 0.600 #4 Device 1 188.00'6.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 #5 Primary 191.50'Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Head (feet) 0.00 0.50 1.00 Width (feet) 5.00 8.00 57.00 Type III 24-hr 25-yr Rainfall=5.25"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 26HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Primary OutFlow Max=38.10 cfs @ 12.42 hrs HW=189.24' (Free Discharge) 1=Culvert (Passes 38.10 cfs of 43.88 cfs potential flow) 2=Orifice/Grate (Orifice Controls 6.15 cfs @ 7.83 fps) 3=Orifice/Grate (Orifice Controls 6.15 cfs @ 7.83 fps) 4=Broad-Crested Rectangular Weir (Weir Controls 25.80 cfs @ 3.46 fps) 5=Custom Weir/Orifice ( Controls 0.00 cfs) Summary for Pond P3: Basin #3 (As Built) Inflow Area = 10.360 ac, 62.74% Impervious, Inflow Depth > 3.11" for 25-yr event Inflow = 37.76 cfs @ 12.08 hrs, Volume= 2.685 af Outflow = 15.17 cfs @ 12.31 hrs, Volume= 2.682 af, Atten= 60%, Lag= 14.2 min Discarded = 1.40 cfs @ 12.31 hrs, Volume= 0.424 af Primary = 13.76 cfs @ 12.31 hrs, Volume= 2.258 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs / 2 Peak Elev= 211.76' @ 12.31 hrs Surf.Area= 10,003 sf Storage= 25,854 cf Plug-Flow detention time= 17.6 min calculated for 2.676 af (100% of inflow) Center-of-Mass det. time= 16.9 min ( 835.3 - 818.4 ) Volume Invert Avail.Storage Storage Description #1 207.10' 67,302 cf Custom Stage Data (Conic) Listed below Elevation Surf.Area Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (cubic-feet) (cubic-feet) (sq-ft) 207.10 0 0 0 0 207.50 1,512 202 202 1,512 208.00 3,206 1,153 1,355 3,208 209.00 4,988 4,064 5,419 5,005 210.00 6,596 5,773 11,193 6,635 211.00 8,446 7,502 18,694 8,510 212.00 10,503 9,456 28,150 10,596 213.00 12,662 11,566 39,716 12,788 214.00 15,015 13,822 53,538 15,178 214.85 17,400 13,764 67,302 17,593 Device Routing Invert Outlet Devices #1 Primary 207.00'30.0" Round Culvert L= 65.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 207.00' / 206.65' S= 0.0054 '/' Cc= 0.900 n= 0.011 Concrete pipe, straight & clean, Flow Area= 4.91 sf #2 Device 1 207.10'12.0" Vert. Orifice/Grate C= 0.600 #3 Device 1 209.75'12.0" Vert. Orifice/Grate C= 0.600 #4 Device 1 211.30'10.0" Vert. Orifice/Grate X 2.00 C= 0.600 #5 Device 1 213.15'11.5' long x 0.5' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 Coef. (English) 2.80 2.92 3.08 3.30 3.32 #6 Primary 213.85'15.0' long x 10.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Type III 24-hr 25-yr Rainfall=5.25"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 27HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64 #7 Discarded 207.10'6.000 in/hr Exfiltration over Wetted area Discarded OutFlow Max=1.40 cfs @ 12.31 hrs HW=211.75' (Free Discharge) 7=Exfiltration (Exfiltration Controls 1.40 cfs) Primary OutFlow Max=13.73 cfs @ 12.31 hrs HW=211.75' (Free Discharge) 1=Culvert (Passes 13.73 cfs of 44.24 cfs potential flow) 2=Orifice/Grate (Orifice Controls 7.71 cfs @ 9.81 fps) 3=Orifice/Grate (Orifice Controls 4.64 cfs @ 5.90 fps) 4=Orifice/Grate (Orifice Controls 1.39 cfs @ 2.29 fps) 5=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) 6=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond P4: Basin #4 (As Built) Inflow Area = 16.100 ac, 50.45% Impervious, Inflow Depth > 3.60" for 25-yr event Inflow = 67.48 cfs @ 12.07 hrs, Volume= 4.827 af Outflow = 25.78 cfs @ 12.32 hrs, Volume= 4.612 af, Atten= 62%, Lag= 14.7 min Primary = 4.54 cfs @ 12.32 hrs, Volume= 3.339 af Secondary = 21.24 cfs @ 12.32 hrs, Volume= 1.272 af Tertiary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 202.93' @ 12.32 hrs Surf.Area= 27,244 sf Storage= 77,671 cf Plug-Flow detention time= 134.1 min calculated for 4.602 af (95% of inflow) Center-of-Mass det. time= 109.4 min ( 913.7 - 804.3 ) Volume Invert Avail.Storage Storage Description #1 199.30' 108,414 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 199.30 14,500 0 0 200.00 17,810 11,308 11,308 202.00 24,412 42,222 53,530 204.00 30,472 54,884 108,414 Device Routing Invert Outlet Devices #1 Primary 199.37'12.0" Round Culvert L= 194.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 199.37' / 198.00' S= 0.0071 '/' Cc= 0.900 n= 0.013 Concrete pipe, bends & connections, Flow Area= 0.79 sf #2 Secondary 202.00'8.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 #3 Tertiary 203.50'15.0' long x 10.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Type III 24-hr 25-yr Rainfall=5.25"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 28HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64 Primary OutFlow Max=4.54 cfs @ 12.32 hrs HW=202.93' (Free Discharge) 1=Culvert (Barrel Controls 4.54 cfs @ 5.78 fps) Secondary OutFlow Max=21.12 cfs @ 12.32 hrs HW=202.93' (Free Discharge) 2=Broad-Crested Rectangular Weir (Weir Controls 21.12 cfs @ 2.83 fps) Tertiary OutFlow Max=0.00 cfs @ 0.00 hrs HW=199.30' (Free Discharge) 3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type III 24-hr 100-yr Rainfall=7.00"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 29HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=11.918 ac 3.90% Impervious Runoff Depth>2.12"Subcatchment PDA-1B: Northwest Corner Tc=5.0 min CN=55 Runoff=27.94 cfs 2.107 af Runoff Area=10.360 ac 62.74% Impervious Runoff Depth>4.69"Subcatchment PDA-1C: Proposed Area on Tc=5.0 min CN=80 Runoff=56.78 cfs 4.050 af Runoff Area=6.172 ac 5.10% Impervious Runoff Depth>4.04"Subcatchment PDA-2A: Northern & Eastern Tc=5.0 min CN=74 Runoff=29.25 cfs 2.078 af Runoff Area=3.490 ac 49.78% Impervious Runoff Depth>5.36"Subcatchment PDA-2B: TCB "Lot 13A" Tc=5.0 min CN=86 Runoff=21.37 cfs 1.560 af Runoff Area=16.100 ac 50.45% Impervious Runoff Depth>5.25"Subcatchment PDA-2C: Southeast Corner Tc=5.0 min CN=85 Runoff=96.96 cfs 7.043 af Runoff Area=7.880 ac 26.57% Impervious Runoff Depth>4.58"Subcatchment PDA-2D: Future Co-Housing Tc=5.0 min CN=79 Runoff=42.28 cfs 3.009 af Inflow=45.34 cfs 5.596 afReach DP-1: Control point for proposed runoff (area 1) Outflow=45.34 cfs 5.596 af Inflow=77.42 cfs 13.262 afReach DP-2: Control Point for proposed drainage Outflow=77.42 cfs 13.262 af Avg. Flow Depth=1.43' Max Vel=4.88 fps Inflow=50.66 cfs 2.792 afReach S1: Drainage Swale (Upper n=0.030 L=85.0' S=0.0118 '/' Capacity=106.17 cfs Outflow=50.57 cfs 2.792 af Avg. Flow Depth=1.42' Max Vel=5.35 fps Inflow=55.45 cfs 6.771 afReach S2: Drainage Swale (Lower n=0.030 L=550.0' S=0.0144 '/' Capacity=117.31 cfs Outflow=54.62 cfs 6.759 af Peak Elev=190.95' Storage=76,604 cf Inflow=84.34 cfs 11.327 afPond P2: Basin #2 (As-Built) Outflow=62.46 cfs 11.181 af Peak Elev=213.01' Storage=39,882 cf Inflow=56.78 cfs 4.050 afPond P3: Basin #3 (As Built) Discarded=1.78 cfs 0.558 af Primary=21.06 cfs 3.488 af Outflow=22.84 cfs 4.046 af Peak Elev=203.56' Storage=95,181 cf Inflow=96.96 cfs 7.043 afPond P4: Basin #4 (As Built) Primary=4.88 cfs 3.980 af Secondary=50.66 cfs 2.792 af Tertiary=0.52 cfs 0.003 af Outflow=56.06 cfs 6.774 af Type III 24-hr 100-yr Rainfall=7.00"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 30HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Subcatchment PDA-1B: Northwest Corner of Site (includes former area PDA-1A) SWITCHED 0.25 ACRES OF IMPERVIOUS TO GRASS HYD GROUP C - THIS REPRESENTS NO DEVELOPMENT NORTHWEST OF VILLAGE HILL ROAD Runoff = 27.94 cfs @ 12.09 hrs, Volume= 2.107 af, Depth> 2.12" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=7.00" Area (ac) CN Description * 0.364 98 Pavement & Roof 3.704 30 Woods, Good, HSG A 1.987 39 >75% Grass cover, Good, HSG A 0.155 90 1/8 acre lots, 65% imp, HSG C 2.145 70 Woods, Good, HSG C 3.563 74 >75% Grass cover, Good, HSG C 11.918 55 Weighted Average 11.453 96.10% Pervious Area 0.465 3.90% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment PDA-1C: Proposed Area on West Side of Site Runoff = 56.78 cfs @ 12.07 hrs, Volume= 4.050 af, Depth> 4.69" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=7.00" Area (ac) CN Description * 6.110 98 Pavement & Roof * 0.390 98 Detention Pond 2.705 39 >75% Grass cover, Good, HSG A 1.155 74 >75% Grass cover, Good, HSG C 10.360 80 Weighted Average 3.860 37.26% Pervious Area 6.500 62.74% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Flow from Watershed Area Type III 24-hr 100-yr Rainfall=7.00"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 31HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Subcatchment PDA-2A: Northern & Eastern Edges of Site Runoff = 29.25 cfs @ 12.08 hrs, Volume= 2.078 af, Depth> 4.04" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=7.00" Area (ac) CN Description * 0.286 98 Pavement & Roof 0.029 98 Water Surface, HSG C 1.907 70 Woods, Good, HSG C 3.950 74 >75% Grass cover, Good, HSG C 6.172 74 Weighted Average 5.857 94.90% Pervious Area 0.315 5.10% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment PDA-2B: TCB "Lot 13A" Project Runoff = 21.37 cfs @ 12.07 hrs, Volume= 1.560 af, Depth> 5.36" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=7.00" Area (ac) CN Description * 1.386 98 Pavement & Roof * 0.068 98 Pond/Rain Garden 0.028 61 >75% Grass cover, Good, HSG B 0.436 90 1/8 acre lots, 65% imp, HSG C 1.572 74 >75% Grass cover, Good, HSG C 3.490 86 Weighted Average 1.753 50.22% Pervious Area 1.737 49.78% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment PDA-2C: Southeast Corner of Site Runoff = 96.96 cfs @ 12.07 hrs, Volume= 7.043 af, Depth> 5.25" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=7.00" Type III 24-hr 100-yr Rainfall=7.00"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 32HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Area (ac) CN Description 7.050 98 Paved parking & roofs * 0.785 98 Detention Pond/Rain Garden 0.443 90 1/8 acre lots, 65% imp, HSG C 1.214 61 >75% Grass cover, Good, HSG B 6.608 74 >75% Grass cover, Good, HSG C 16.100 85 Weighted Average 7.977 49.55% Pervious Area 8.123 50.45% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment PDA-2D: Future Co-Housing Site Runoff = 42.28 cfs @ 12.07 hrs, Volume= 3.009 af, Depth> 4.58" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=7.00" Area (ac) CN Description * 1.748 98 Pavement & Roof * 0.175 98 Pavement & Roof * 0.171 98 Detention Basin 0.969 61 >75% Grass cover, Good, HSG B 0.410 70 Woods, Good, HSG C 4.407 74 >75% Grass cover, Good, HSG C 7.880 79 Weighted Average 5.786 73.43% Pervious Area 2.094 26.57% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Reach DP-1: Control point for proposed runoff (area 1) Inflow Area = 22.278 ac, 31.26% Impervious, Inflow Depth > 3.01" for 100-yr event Inflow = 45.34 cfs @ 12.11 hrs, Volume= 5.596 af Outflow = 45.34 cfs @ 12.11 hrs, Volume= 5.596 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=7.00"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 33HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Reach DP-2: Control Point for proposed drainage Inflow Area = 33.642 ac, 36.47% Impervious, Inflow Depth > 4.73" for 100-yr event Inflow = 77.42 cfs @ 12.12 hrs, Volume= 13.262 af Outflow = 77.42 cfs @ 12.12 hrs, Volume= 13.262 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Reach S1: Drainage Swale (Upper Segment) Inflow = 50.66 cfs @ 12.19 hrs, Volume= 2.792 af Outflow = 50.57 cfs @ 12.20 hrs, Volume= 2.792 af, Atten= 0%, Lag= 0.7 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 4.88 fps, Min. Travel Time= 0.3 min Avg. Velocity = 2.19 fps, Avg. Travel Time= 0.6 min Peak Storage= 885 cf @ 12.20 hrs Average Depth at Peak Storage= 1.43' Bank-Full Depth= 2.00' Flow Area= 18.0 sf, Capacity= 106.17 cfs 3.00' x 2.00' deep channel, n= 0.030 Earth, grassed & winding Side Slope Z-value= 3.0 '/' Top Width= 15.00' Length= 85.0' Slope= 0.0118 '/' Inlet Invert= 202.00', Outlet Invert= 201.00' ‡ Summary for Reach S2: Drainage Swale (Lower Segment) Inflow Area = 16.100 ac, 50.45% Impervious, Inflow Depth > 5.05" for 100-yr event Inflow = 55.45 cfs @ 12.20 hrs, Volume= 6.771 af Outflow = 54.62 cfs @ 12.26 hrs, Volume= 6.759 af, Atten= 1%, Lag= 3.5 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 5.35 fps, Min. Travel Time= 1.7 min Avg. Velocity = 2.30 fps, Avg. Travel Time= 4.0 min Peak Storage= 5,671 cf @ 12.22 hrs Average Depth at Peak Storage= 1.42' Bank-Full Depth= 2.00' Flow Area= 18.0 sf, Capacity= 117.31 cfs 3.00' x 2.00' deep channel, n= 0.030 Earth, grassed & winding Side Slope Z-value= 3.0 '/' Top Width= 15.00' Length= 550.0' Slope= 0.0144 '/' Inlet Invert= 197.90', Outlet Invert= 190.00' Type III 24-hr 100-yr Rainfall=7.00"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 34HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC ‡ Summary for Pond P2: Basin #2 (As-Built) Inflow Area = 27.470 ac, 43.52% Impervious, Inflow Depth > 4.95" for 100-yr event Inflow = 84.34 cfs @ 12.10 hrs, Volume= 11.327 af Outflow = 62.46 cfs @ 12.42 hrs, Volume= 11.181 af, Atten= 26%, Lag= 19.2 min Primary = 62.46 cfs @ 12.42 hrs, Volume= 11.181 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Starting Elev= 186.10' Surf.Area= 11,124 sf Storage= 6,465 cf Peak Elev= 190.95' @ 12.42 hrs Surf.Area= 18,769 sf Storage= 76,604 cf (70,139 cf above start) Plug-Flow detention time= 42.0 min calculated for 11.010 af (97% of inflow) Center-of-Mass det. time= 22.8 min ( 876.3 - 853.5 ) Volume Invert Avail.Storage Storage Description #1 185.50' 97,586 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 185.50 10,431 0 0 186.00 11,004 5,359 5,359 188.00 13,402 24,406 29,765 190.00 16,648 30,050 59,815 192.00 21,123 37,771 97,586 Device Routing Invert Outlet Devices #1 Primary 186.08'36.0" Round Culvert L= 212.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 186.08' / 181.31' S= 0.0225 '/' Cc= 0.900 n= 0.013, Flow Area= 7.07 sf #2 Device 1 186.10'12.0" Vert. Orifice/Grate C= 0.600 #3 Device 1 186.10'12.0" Vert. Orifice/Grate C= 0.600 #4 Device 1 188.00'6.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 #5 Primary 191.50'Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Head (feet) 0.00 0.50 1.00 Width (feet) 5.00 8.00 57.00 Type III 24-hr 100-yr Rainfall=7.00"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 35HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Primary OutFlow Max=62.38 cfs @ 12.42 hrs HW=190.94' (Free Discharge) 1=Culvert (Inlet Controls 62.38 cfs @ 8.83 fps) 2=Orifice/Grate (Passes < 7.88 cfs potential flow) 3=Orifice/Grate (Passes < 7.88 cfs potential flow) 4=Broad-Crested Rectangular Weir (Passes < 100.37 cfs potential flow) 5=Custom Weir/Orifice ( Controls 0.00 cfs) Summary for Pond P3: Basin #3 (As Built) Inflow Area = 10.360 ac, 62.74% Impervious, Inflow Depth > 4.69" for 100-yr event Inflow = 56.78 cfs @ 12.07 hrs, Volume= 4.050 af Outflow = 22.84 cfs @ 12.30 hrs, Volume= 4.046 af, Atten= 60%, Lag= 13.4 min Discarded = 1.78 cfs @ 12.30 hrs, Volume= 0.558 af Primary = 21.06 cfs @ 12.30 hrs, Volume= 3.488 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs / 2 Peak Elev= 213.01' @ 12.30 hrs Surf.Area= 12,690 sf Storage= 39,882 cf Plug-Flow detention time= 19.4 min calculated for 4.046 af (100% of inflow) Center-of-Mass det. time= 18.7 min ( 825.4 - 806.7 ) Volume Invert Avail.Storage Storage Description #1 207.10' 67,302 cf Custom Stage Data (Conic) Listed below Elevation Surf.Area Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (cubic-feet) (cubic-feet) (sq-ft) 207.10 0 0 0 0 207.50 1,512 202 202 1,512 208.00 3,206 1,153 1,355 3,208 209.00 4,988 4,064 5,419 5,005 210.00 6,596 5,773 11,193 6,635 211.00 8,446 7,502 18,694 8,510 212.00 10,503 9,456 28,150 10,596 213.00 12,662 11,566 39,716 12,788 214.00 15,015 13,822 53,538 15,178 214.85 17,400 13,764 67,302 17,593 Device Routing Invert Outlet Devices #1 Primary 207.00'30.0" Round Culvert L= 65.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 207.00' / 206.65' S= 0.0054 '/' Cc= 0.900 n= 0.011 Concrete pipe, straight & clean, Flow Area= 4.91 sf #2 Device 1 207.10'12.0" Vert. Orifice/Grate C= 0.600 #3 Device 1 209.75'12.0" Vert. Orifice/Grate C= 0.600 #4 Device 1 211.30'10.0" Vert. Orifice/Grate X 2.00 C= 0.600 #5 Device 1 213.15'11.5' long x 0.5' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 Coef. (English) 2.80 2.92 3.08 3.30 3.32 #6 Primary 213.85'15.0' long x 10.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Type III 24-hr 100-yr Rainfall=7.00"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 36HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64 #7 Discarded 207.10'6.000 in/hr Exfiltration over Wetted area Discarded OutFlow Max=1.78 cfs @ 12.30 hrs HW=213.01' (Free Discharge) 7=Exfiltration (Exfiltration Controls 1.78 cfs) Primary OutFlow Max=21.06 cfs @ 12.30 hrs HW=213.01' (Free Discharge) 1=Culvert (Passes 21.06 cfs of 51.57 cfs potential flow) 2=Orifice/Grate (Orifice Controls 8.80 cfs @ 11.20 fps) 3=Orifice/Grate (Orifice Controls 6.28 cfs @ 8.00 fps) 4=Orifice/Grate (Orifice Controls 5.98 cfs @ 5.48 fps) 5=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) 6=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond P4: Basin #4 (As Built) Inflow Area = 16.100 ac, 50.45% Impervious, Inflow Depth > 5.25" for 100-yr event Inflow = 96.96 cfs @ 12.07 hrs, Volume= 7.043 af Outflow = 56.06 cfs @ 12.19 hrs, Volume= 6.774 af, Atten= 42%, Lag= 7.2 min Primary = 4.88 cfs @ 12.19 hrs, Volume= 3.980 af Secondary = 50.66 cfs @ 12.19 hrs, Volume= 2.792 af Tertiary = 0.52 cfs @ 12.20 hrs, Volume= 0.003 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 203.56' @ 12.19 hrs Surf.Area= 29,126 sf Storage= 95,181 cf Plug-Flow detention time= 111.8 min calculated for 6.774 af (96% of inflow) Center-of-Mass det. time= 89.9 min ( 883.7 - 793.8 ) Volume Invert Avail.Storage Storage Description #1 199.30' 108,414 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 199.30 14,500 0 0 200.00 17,810 11,308 11,308 202.00 24,412 42,222 53,530 204.00 30,472 54,884 108,414 Device Routing Invert Outlet Devices #1 Primary 199.37'12.0" Round Culvert L= 194.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 199.37' / 198.00' S= 0.0071 '/' Cc= 0.900 n= 0.013 Concrete pipe, bends & connections, Flow Area= 0.79 sf #2 Secondary 202.00'8.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 #3 Tertiary 203.50'15.0' long x 10.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Type III 24-hr 100-yr Rainfall=7.00"Village Hill - TCB - Proposed Printed 1/16/2018Prepared by Microsoft Page 37HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64 Primary OutFlow Max=4.88 cfs @ 12.19 hrs HW=203.55' (Free Discharge) 1=Culvert (Barrel Controls 4.88 cfs @ 6.21 fps) Secondary OutFlow Max=50.40 cfs @ 12.19 hrs HW=203.55' (Free Discharge) 2=Broad-Crested Rectangular Weir (Weir Controls 50.40 cfs @ 4.06 fps) Tertiary OutFlow Max=0.45 cfs @ 12.20 hrs HW=203.55' (Free Discharge) 3=Broad-Crested Rectangular Weir (Weir Controls 0.45 cfs @ 0.57 fps) Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Appendix E – Water Quality Calculations Project: Summit Oaks at Village Hill Location: Northamption, MA Prepared For: Berkshire Engineering Purpose: Reference: Procedure: where: A = impervious surface drainage area (in square miles) WQV = water quality volume in watershed inches (1/2" in this case) Structure Name Impv. (acres) A (miles2) tc (min) tc (hr) WQV (in)qu (csm/in.) Q (cfs) SWTC 3.80 0.0059375 15.0 0.250 0.50 606.00 1.80 qu = the unit peak discharge, in csm/in. To calculate the water quality flow rate (WQF) over a given site area. In this situation the WQF is derived from the first 1/2" of runoff from the contributing impervious surface. Massachusetts Dept. of Environmental Protection Wetlands Program / United States Department of Agriculture Natural Resources Conservation Service TR-55 Manual Determine unit peak discharge using Figure 1 or 2. Figure 2 is in tabular form so is preferred. Using the tc, read the unit peak discharge (qu) from Figure 1 or Table in Figure 2. qu is expressed in the following units: cfs/mi2/watershed inches (csm/in). Compute Q Rate using the following equation: Q = (qu) (A) (WQV) Q = flow rate associated with first 1/2" of runoff Area 3.80 ac SWTU Weighted C 0.9 69 tc 15 min Particle size 0 CDS Model 2020-5 2.2 cfs CDS Hydraulic Cap cfs Rainfall Intensity1 (in/hr) Percent Rainfall Volume1 Cumulative Rainfall Volume Total Flowrate (cfs) Treated Flowrate (cfs) Incremental Removal (%) 0.02 10.2% 10.2% 0.07 0.07 10.2 0.04 9.6% 19.8% 0.14 0.14 9.5 0.06 9.4% 29.3% 0.21 0.21 9.2 0.08 7.7% 37.0% 0.27 0.27 7.5 0.10 8.6% 45.6% 0.34 0.34 8.2 0.12 6.3% 51.9% 0.41 0.41 5.9 0.14 4.7% 56.5% 0.48 0.48 4.3 0.16 4.6% 61.2% 0.55 0.55 4.2 0.18 3.5% 64.7% 0.62 0.62 3.2 0.20 4.3% 69.1% 0.68 0.68 3.9 0.25 8.0% 77.1% 0.86 0.86 6.9 0.30 5.6% 82.7% 1.03 1.03 4.6 0.35 4.4% 87.0% 1.20 1.20 3.5 0.40 2.5% 89.5% 1.37 1.37 1.9 0.45 2.5% 92.1% 1.54 1.54 1.9 0.50 1.4% 93.5% 1.71 1.71 1.0 0.75 5.0% 98.5% 2.57 2.20 2.7 1.00 1.0% 99.5% 3.42 2.20 0.4 1.50 0.0% 99.5% 5.13 2.20 0.0 2.00 0.0% 99.5% 6.84 2.20 0.0 3.00 0.5% 100.0% 10.26 2.20 0.1 89.0 6.5% 92.1% 82.5% 1 - Based on 10 years of hourly precipitation data from NCDC Station 770, Boston WSFO AP, Suffolk County, MA 2 - Reduction due to use of 60-minute data for a site that has a time of concentration less than 30-minutes. Predicted Net Annual Load Removal Efficiency = Predicted % Annual Rainfall Treated = BASED ON THE RATIONAL RAINFALL METHOD BASED ON AN AVERAGE PARTICLE SIZE OF 125 MICRONS SUMMIT OAKS AT VILLAGE HILL Removal Efficiency Adjustment2 = CDS ESTIMATED NET ANNUAL SOLIDS LOAD REDUCTION Rainfall Station # NORTHAMPTION, MA Unit Site Designation CDS Treatment Capacity INSTRUCTIONS:Non-automated: Mar. 4, 20081. Sheet is nonautomated. Print sheet and complete using hand calculations. Column A and B: See MassDEP Structural BMP Table2. The calculations must be completed using the Column Headings specified in Chart and Not the Excel Column Headings3. To complete Chart Column D, multiple Column B value within Row x Column C value within Row4. To complete Chart Column E value, subtract Column D value within Row from Column C within Row5. Total TSS Removal = Sum All Values in Column DLocation: A B C D ETSS Removal Starting TSS Amount RemainingBMP1Rate1Load* Removed (B*C) Load (C-D)1.00Total TSS Removal =Separate Form Needs to be Completed for Each Outlet or BMP TrainProject:Prepared By:*Equals remaining load from previous BMP (E)Date:which enters the BMPTSS Removal Calculation WorksheetNon-automated TSS Calculation Sheet must be used if Proprietary BMP Proposed1. From MassDEP Stormwater Handbook Vol. 1Mass. Dept. of Environmental Protection INSTRUCTIONS:Non-automated: Mar. 4, 20081. Sheet is nonautomated. Print sheet and complete using hand calculations. Column A and B: See MassDEP Structural BMP Table2. The calculations must be completed using the Column Headings specified in Chart and Not the Excel Column Headings3. To complete Chart Column D, multiple Column B value within Row x Column C value within Row4. To complete Chart Column E value, subtract Column D value within Row from Column C within Row5. Total TSS Removal = Sum All Values in Column DLocation: A B C D ETSS Removal Starting TSS Amount RemainingBMP1Rate1Load* Removed (B*C) Load (C-D)1.00Total TSS Removal =Separate Form Needs to be Completed for Each Outlet or BMP TrainProject:Prepared By:*Equals remaining load from previous BMP (E)Date:which enters the BMPTSS Removal Calculation WorksheetNon-automated TSS Calculation Sheet must be used if Proprietary BMP Proposed1. From MassDEP Stormwater Handbook Vol. 1Mass. Dept. of Environmental Protection INSTRUCTIONS:Non-automated: Mar. 4, 20081. Sheet is nonautomated. Print sheet and complete using hand calculations. Column A and B: See MassDEP Structural BMP Table2. The calculations must be completed using the Column Headings specified in Chart and Not the Excel Column Headings3. To complete Chart Column D, multiple Column B value within Row x Column C value within Row4. To complete Chart Column E value, subtract Column D value within Row from Column C within Row5. Total TSS Removal = Sum All Values in Column DLocation: A B C D ETSS Removal Starting TSS Amount RemainingBMP1Rate1Load* Removed (B*C) Load (C-D)1.00Total TSS Removal =Separate Form Needs to be Completed for Each Outlet or BMP TrainProject:Prepared By:*Equals remaining load from previous BMP (E)Date:which enters the BMPTSS Removal Calculation WorksheetNon-automated TSS Calculation Sheet must be used if Proprietary BMP Proposed1. From MassDEP Stormwater Handbook Vol. 1Mass. Dept. of Environmental Protection INSTRUCTIONS:Non-automated: Mar. 4, 20081. Sheet is nonautomated. Print sheet and complete using hand calculations. Column A and B: See MassDEP Structural BMP Table2. The calculations must be completed using the Column Headings specified in Chart and Not the Excel Column Headings3. To complete Chart Column D, multiple Column B value within Row x Column C value within Row4. To complete Chart Column E value, subtract Column D value within Row from Column C within Row5. Total TSS Removal = Sum All Values in Column DLocation: A B C D ETSS Removal Starting TSS Amount RemainingBMP1Rate1Load* Removed (B*C) Load (C-D)1.00Total TSS Removal =Separate Form Needs to be Completed for Each Outlet or BMP TrainProject:Prepared By:*Equals remaining load from previous BMP (E)Date:which enters the BMPTSS Removal Calculation WorksheetNon-automated TSS Calculation Sheet must be used if Proprietary BMP Proposed1. From MassDEP Stormwater Handbook Vol. 1Mass. Dept. of Environmental Protection INSTRUCTIONS:Non-automated: Mar. 4, 20081. Sheet is nonautomated. Print sheet and complete using hand calculations. Column A and B: See MassDEP Structural BMP Table2. The calculations must be completed using the Column Headings specified in Chart and Not the Excel Column Headings3. To complete Chart Column D, multiple Column B value within Row x Column C value within Row4. To complete Chart Column E value, subtract Column D value within Row from Column C within Row5. Total TSS Removal = Sum All Values in Column DLocation: A B C D ETSS Removal Starting TSS Amount RemainingBMP1Rate1Load* Removed (B*C) Load (C-D)1.00Total TSS Removal =Separate Form Needs to be Completed for Each Outlet or BMP TrainProject:Prepared By:*Equals remaining load from previous BMP (E)Date:which enters the BMPTSS Removal Calculation WorksheetNon-automated TSS Calculation Sheet must be used if Proprietary BMP Proposed1. From MassDEP Stormwater Handbook Vol. 1Mass. Dept. of Environmental Protection INSTRUCTIONS:Non-automated: Mar. 4, 20081. Sheet is nonautomated. Print sheet and complete using hand calculations. Column A and B: See MassDEP Structural BMP Table2. The calculations must be completed using the Column Headings specified in Chart and Not the Excel Column Headings3. To complete Chart Column D, multiple Column B value within Row x Column C value within Row4. To complete Chart Column E value, subtract Column D value within Row from Column C within Row5. Total TSS Removal = Sum All Values in Column DLocation: A B C D ETSS Removal Starting TSS Amount RemainingBMP1Rate1Load* Removed (B*C) Load (C-D)1.00Total TSS Removal =Separate Form Needs to be Completed for Each Outlet or BMP TrainProject:Prepared By:*Equals remaining load from previous BMP (E)Date:which enters the BMPTSS Removal Calculation WorksheetNon-automated TSS Calculation Sheet must be used if Proprietary BMP Proposed1. From MassDEP Stormwater Handbook Vol. 1Mass. Dept. of Environmental Protection Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Appendix F – Outlet Protection Riprap Design Calculations 4 Allen Place, Northampton, MA 01060 (413) 582-7000 bdg@berkshiredesign.com The Berkshire Design Group, Inc. September 28, 2017 Doug MacDonald Northampton DPW RE: Village Hill – The Community Builders Outlet Protection Design Berkshire Design has prepared this summary of the design calculations supporting the dimensions and sizing of the riprap apron at the 24” outlet of the proposed drainage system for The Community Builders Lot 13A project. The outlet protection design is based on the 100-year flow rate discharged by the pipe. The pipe flow summary table was created to estimate pipe flow for the 100-year storm intensity (8.8” as per the Mass DOT Highway Design Manual, Chapter 8). The drainage area plan and revised summary table are attached for reference. This analysis estimated that the proposed 24” outlet pipe will carry a peak flow rate of approximately 38 cfs during the 100-year storm. Based on the estimated peak flow rate, the NRCS method for design of outlet protection was used to size the protective apron and median stone diameter for riprap. As shown in the proposed chart, apron length should be a minimum of 22’ and the median stone size should be 10”. Consistent with NRCS guidance, the apron should flare from a width of 6’ at the outlet to a width of 24’ at the distant end of the apron. Design guidance from HEC-11 Riprap Design Manual recommends the following stone size distribution, where d50 is the designed median stone size: Size Guidance Equivalent Size Percent Smaller 1.5(d50) – 1.7(d50) 14” – 15” 100% 1.2(d50) – 1.4(d50) 11” – 13” 85% 1.0(d50) – 1.4(d50) 9” –13” 50% 0.4(d50) – 0.6(d50) 4” – 5” 15% Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Appendix G – Massachusetts Stormwater Checklist Stormwater Checklist.docx • 04/01/08 Stormwater Report Checklist • Page 1 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report A. Introduction Important: When filling out forms on the computer, use only the tab key to move your cursor - do not use the return key. A Stormwater Report must be submitted with the Notice of Intent permit application to document compliance with the Stormwater Management Standards. The following checklist is NOT a substitute for the Stormwater Report (which should provide more substantive and detailed information) but is offered here as a tool to help the applicant organize their Stormwater Management documentation for their Report and for the reviewer to assess this information in a consistent format. As noted in the Checklist, the Stormwater Report must contain the engineering computations and supporting information set forth in Volume 3 of the Massachusetts Stormwater Handbook. The Stormwater Report must be prepared and certified by a Registered Professional Engineer (RPE) licensed in the Commonwealth. The Stormwater Report must include: · The Stormwater Checklist completed and stamped by a Registered Professional Engineer (see page 2) that certifies that the Stormwater Report contains all required submittals.1 This Checklist is to be used as the cover for the completed Stormwater Report. · Applicant/Project Name · Project Address · Name of Firm and Registered Professional Engineer that prepared the Report · Long-Term Pollution Prevention Plan required by Standards 4-6 · Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan required by Standard 82 · Operation and Maintenance Plan required by Standard 9 In addition to all plans and supporting information, the Stormwater Report must include a brief narrative describing stormwater management practices, including environmentally sensitive site design and LID techniques, along with a diagram depicting runoff through the proposed BMP treatment train. Plans are required to show existing and proposed conditions, identify all wetland resource areas, NRCS soil types, critical areas, Land Uses with Higher Potential Pollutant Loads (LUHPPL), and any areas on the site where infiltration rate is greater than 2.4 inches per hour. The Plans shall identify the drainage areas for both existing and proposed conditions at a scale that enables verification of supporting calculations. As noted in the Checklist, the Stormwater Management Report shall document compliance with each of the Stormwater Management Standards as provided in the Massachusetts Stormwater Handbook. The soils evaluation and calculations shall be done using the methodologies set forth in Volume 3 of the Massachusetts Stormwater Handbook. To ensure that the Stormwater Report is complete, applicants are required to fill in the Stormwater Report Checklist by checking the box to indicate that the specified information has been included in the Stormwater Report. If any of the information specified in the checklist has not been submitted, the applicant must provide an explanation. The completed Stormwater Report Checklist and Certification must be submitted with the Stormwater Report. 1 The Stormwater Report may also include the Illicit Discharge Compliance Statement required by Standard 10. If not included in the Stormwater Report, the Illicit Discharge Compliance Statement must be submitted prior to the discharge of stormwater runoff to the post-construction best management practices. 2 For some complex projects, it may not be possible to include the Construction Period Erosion and Sedimentation Control Plan in the Stormwater Report. In that event, the issuing authority has the discretion to issue an Order of Conditions that approves the project and includes a condition requiring the proponent to submit the Construction Period Erosion and Sedimentation Control Plan before commencing any land disturbance activity on the site. Stormwater Checklist.docx • 04/01/08 Stormwater Report Checklist • Page 3 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) LID Measures: Stormwater Standards require LID measures to be considered. Document what environmentally sensitive design and LID Techniques were considered during the planning and design of the project: No disturbance to any Wetland Resource Areas Site Design Practices (e.g. clustered development, reduced frontage setbacks) Reduced Impervious Area (Redevelopment Only) Minimizing disturbance to existing trees and shrubs LID Site Design Credit Requested: Credit 1 Credit 2 Credit 3 Use of “country drainage” versus curb and gutter conveyance and pipe Bioretention Cells (includes Rain Gardens) Constructed Stormwater Wetlands (includes Gravel Wetlands designs) Treebox Filter Water Quality Swale Grass Channel Green Roof Other (describe): Standard 1: No New Untreated Discharges No new untreated discharges Outlets have been designed so there is no erosion or scour to wetlands and waters of the Commonwealth Supporting calculations specified in Volume 3 of the Massachusetts Stormwater Handbook included. Stormwater Checklist.docx • 04/01/08 Stormwater Report Checklist • Page 4 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 2: Peak Rate Attenuation Standard 2 waiver requested because the project is located in land subject to coastal storm flowage and stormwater discharge is to a wetland subject to coastal flooding. Evaluation provided to determine whether off-site flooding increases during the 100-year 24-hour storm. Calculations provided to show that post-development peak discharge rates do not exceed pre- development rates for the 2-year and 10-year 24-hour storms. If evaluation shows that off-site flooding increases during the 100-year 24-hour storm, calculations are also provided to show that post-development peak discharge rates do not exceed pre-development rates for the 100-year 24- hour storm. Standard 3: Recharge Soil Analysis provided. Required Recharge Volume calculation provided. Required Recharge volume reduced through use of the LID site Design Credits. Sizing the infiltration, BMPs is based on the following method: Check the method used. Static Simple Dynamic Dynamic Field1 Runoff from all impervious areas at the site discharging to the infiltration BMP. Runoff from all impervious areas at the site is not discharging to the infiltration BMP and calculations are provided showing that the drainage area contributing runoff to the infiltration BMPs is sufficient to generate the required recharge volume. Recharge BMPs have been sized to infiltrate the Required Recharge Volume. Recharge BMPs have been sized to infiltrate the Required Recharge Volume only to the maximum extent practicable for the following reason: Site is comprised solely of C and D soils and/or bedrock at the land surface M.G.L. c. 21E sites pursuant to 310 CMR 40.0000 Solid Waste Landfill pursuant to 310 CMR 19.000 Project is otherwise subject to Stormwater Management Standards only to the maximum extent practicable. Calculations showing that the infiltration BMPs will drain in 72 hours are provided. Property includes a M.G.L. c. 21E site or a solid waste landfill and a mounding analysis is included. 1 80% TSS removal is required prior to discharge to infiltration BMP if Dynamic Field method is used. Stormwater Checklist.docx • 04/01/08 Stormwater Report Checklist • Page 5 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 3: Recharge (continued) The infiltration BMP is used to attenuate peak flows during storms greater than or equal to the 10- year 24-hour storm and separation to seasonal high groundwater is less than 4 feet and a mounding analysis is provided. Documentation is provided showing that infiltration BMPs do not adversely impact nearby wetland resource areas. Standard 4: Water Quality The Long-Term Pollution Prevention Plan typically includes the following: · Good housekeeping practices; · Provisions for storing materials and waste products inside or under cover; · Vehicle washing controls; · Requirements for routine inspections and maintenance of stormwater BMPs; · Spill prevention and response plans; · Provisions for maintenance of lawns, gardens, and other landscaped areas; · Requirements for storage and use of fertilizers, herbicides, and pesticides; · Pet waste management provisions; · Provisions for operation and management of septic systems; · Provisions for solid waste management; · Snow disposal and plowing plans relative to Wetland Resource Areas; · Winter Road Salt and/or Sand Use and Storage restrictions; · Street sweeping schedules; · Provisions for prevention of illicit discharges to the stormwater management system; · Documentation that Stormwater BMPs are designed to provide for shutdown and containment in the event of a spill or discharges to or near critical areas or from LUHPPL; · Training for staff or personnel involved with implementing Long-Term Pollution Prevention Plan; · List of Emergency contacts for implementing Long-Term Pollution Prevention Plan. A Long-Term Pollution Prevention Plan is attached to Stormwater Report and is included as an attachment to the Wetlands Notice of Intent. Treatment BMPs subject to the 44% TSS removal pretreatment requirement and the one inch rule for calculating the water quality volume are included, and discharge: is within the Zone II or Interim Wellhead Protection Area is near or to other critical areas is within soils with a rapid infiltration rate (greater than 2.4 inches per hour) involves runoff from land uses with higher potential pollutant loads. The Required Water Quality Volume is reduced through use of the LID site Design Credits. Calculations documenting that the treatment train meets the 80% TSS removal requirement and, if applicable, the 44% TSS removal pretreatment requirement, are provided. Stormwater Checklist.docx • 04/01/08 Stormwater Report Checklist • Page 6 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 4: Water Quality (continued) The BMP is sized (and calculations provided) based on: The ½” or 1” Water Quality Volume or The equivalent flow rate associated with the Water Quality Volume and documentation is provided showing that the BMP treats the required water quality volume. The applicant proposes to use proprietary BMPs, and documentation supporting use of proprietary BMP and proposed TSS removal rate is provided. This documentation may be in the form of the propriety BMP checklist found in Volume 2, Chapter 4 of the Massachusetts Stormwater Handbook and submitting copies of the TARP Report, STEP Report, and/or other third party studies verifying performance of the proprietary BMPs. A TMDL exists that indicates a need to reduce pollutants other than TSS and documentation showing that the BMPs selected are consistent with the TMDL is provided. Standard 5: Land Uses With Higher Potential Pollutant Loads (LUHPPLs) The NPDES Multi-Sector General Permit covers the land use and the Stormwater Pollution Prevention Plan (SWPPP) has been included with the Stormwater Report. The NPDES Multi-Sector General Permit covers the land use and the SWPPP will be submitted prior to the discharge of stormwater to the post-construction stormwater BMPs. The NPDES Multi-Sector General Permit does not cover the land use. LUHPPLs are located at the site and industry specific source control and pollution prevention measures have been proposed to reduce or eliminate the exposure of LUHPPLs to rain, snow, snow melt and runoff, and been included in the long term Pollution Prevention Plan. All exposure has been eliminated. All exposure has not been eliminated and all BMPs selected are on MassDEP LUHPPL list. The LUHPPL has the potential to generate runoff with moderate to higher concentrations of oil and grease (e.g. all parking lots with >1000 vehicle trips per day) and the treatment train includes an oil grit separator, a filtering bioretention area, a sand filter or equivalent. Standard 6: Critical Areas The discharge is near or to a critical area and the treatment train includes only BMPs that MassDEP has approved for stormwater discharges to or near that particular class of critical area. Critical areas and BMPs are identified in the Stormwater Report. Stormwater Checklist.docx • 04/01/08 Stormwater Report Checklist • Page 7 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 7: Redevelopments and Other Projects Subject to the Standards only to the maximum extent practicable The project is subject to the Stormwater Management Standards only to the maximum Extent Practicable as a: Limited Project Small Residential Projects: 5-9 single family houses or 5-9 units in a multi-family development provided there is no discharge that may potentially affect a critical area. Small Residential Projects: 2-4 single family houses or 2-4 units in a multi-family development with a discharge to a critical area Marina and/or boatyard provided the hull painting, service and maintenance areas are protected from exposure to rain, snow, snow melt and runoff Bike Path and/or Foot Path Redevelopment Project Redevelopment portion of mix of new and redevelopment. Certain standards are not fully met (Standard No. 1, 8, 9, and 10 must always be fully met) and an explanation of why these standards are not met is contained in the Stormwater Report. The project involves redevelopment and a description of all measures that have been taken to improve existing conditions is provided in the Stormwater Report. The redevelopment checklist found in Volume 2 Chapter 3 of the Massachusetts Stormwater Handbook may be used to document that the proposed stormwater management system (a) complies with Standards 2, 3 and the pretreatment and structural BMP requirements of Standards 4-6 to the maximum extent practicable and (b) improves existing conditions. Standard 8: Construction Period Pollution Prevention and Erosion and Sedimentation Control A Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan must include the following information: · Narrative; · Construction Period Operation and Maintenance Plan; · Names of Persons or Entity Responsible for Plan Compliance; · Construction Period Pollution Prevention Measures; · Erosion and Sedimentation Control Plan Drawings; · Detail drawings and specifications for erosion control BMPs, including sizing calculations; · Vegetation Planning; · Site Development Plan; · Construction Sequencing Plan; · Sequencing of Erosion and Sedimentation Controls; · Operation and Maintenance of Erosion and Sedimentation Controls; · Inspection Schedule; · Maintenance Schedule; · Inspection and Maintenance Log Form. A Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan containing the information set forth above has been included in the Stormwater Report. Stormwater Checklist.docx • 04/01/08 Stormwater Report Checklist • Page 8 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 8: Construction Period Pollution Prevention and Erosion and Sedimentation Control (continued) The project is highly complex and information is included in the Stormwater Report that explains why it is not possible to submit the Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan with the application. A Construction Period Pollution Prevention and Erosion and Sedimentation Control has not been included in the Stormwater Report but will be submitted before land disturbance begins. The project is not covered by a NPDES Construction General Permit. The project is covered by a NPDES Construction General Permit and a copy of the SWPPP is in the Stormwater Report. The project is covered by a NPDES Construction General Permit but no SWPPP been submitted. The SWPPP will be submitted BEFORE land disturbance begins. Standard 9: Operation and Maintenance Plan The Post Construction Operation and Maintenance Plan is included in the Stormwater Report and includes the following information: Name of the stormwater management system owners; Party responsible for operation and maintenance; Schedule for implementation of routine and non-routine maintenance tasks; Plan showing the location of all stormwater BMPs maintenance access areas; Description and delineation of public safety features; Estimated operation and maintenance budget; and Operation and Maintenance Log Form. The responsible party is not the owner of the parcel where the BMP is located and the Stormwater Report includes the following submissions: A copy of the legal instrument (deed, homeowner’s association, utility trust or other legal entity) that establishes the terms of and legal responsibility for the operation and maintenance of the project site stormwater BMPs; A plan and easement deed that allows site access for the legal entity to operate and maintain BMP functions. Standard 10: Prohibition of Illicit Discharges The Long-Term Pollution Prevention Plan includes m easures to prevent illicit discharges; An Illicit Discharge Compliance Statement is attached; NO Illicit Discharge Compliance Statement is attached but will be submitted prior to the discharge of any stormwater to post-construction BMPs. Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Appendix H – Stormwater Management System – Operation & Maintenance Plan THE COMMUNITY BUILDERS – VILLAGE HILL, NORTHAMPTON, MA STORMWATER MANAGEMENT SYSTEM MAINTENANCE LOG MAINTENANCE ACTIVITES BY STAFF Fill in date of activity on top line, and initial next to each activity. See O&M plan for full description of maintenance activities. Some activities must be performed more frequently during Year 1. Inspect Catch Basins Every 3 Months Inspect Stormwater Treatment Chamber Every 6 Months Inspect & Repair Rain Gardens Every 3 Months Inspect Curb Inlets Every 6 Months THE COMMUNITY BUILDERS – VILLAGE HILL, NORTHAMPTON, MA STORMWATER MANAGEMENT SYSTEM MAINTENANCE LOG MAINTENANCE ACTIVITES BY SERVICE CONTRACTOR STREET SWEEPING (Every 6 Months, Recommended in Late March or April) Date Scheduled Contractor Name Date Completed CLEAN CATCH BASINS & TREATMENT CHAMBER, DISPOSE OF SEDIMENT (Every 12 Months, or as needed based on Catch Basin Inspections) Date Scheduled Contractor Name Date Completed INSPECTION & REPORT BY AN ENGINEER Required every year before October 1st. Chris Chamberland, Berkshire Design Group, Northampton, MA (413) 582-7000 chrisc@berkshiredesign.com Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 1 Stormwater Management System Operation & Maintenance Plan “Lot 13” 65-Unit Apartment Building (Map 31C, Lot 17) During Construction The Contractor shall be responsible for inspection and maintenance during construction. At all times, siltation fabric fencing, stakes and straw bales/wattles, sufficient to construct a sedimentation control barrier a minimum of 50 feet long, shall be stockpiled on the site in order to repair established barriers which may be damaged or breached. An inspection of all erosion control and stormwater management systems shall be conducted by the Contractor at least once a week and during all rain storms until the completion of construction. In case of any noted breach or failure, the Contractor shall immediately make appropriate repairs to any erosion control system and notify the engineer of any problems involving stormwater management systems. A rain storm shall be defined as any of the following: · A storm in which rain is predicted to last for twelve consecutive hours or more. · A storm for which a flash flood watch or warning is issued. · A single storm predicted to have a cumulative rainfall of greater than one-half inch. · A storm not meeting the previous three thresholds but which would mark a third consecutive day of measurable rainfall. The Contractor shall also inspect the erosion control and stormwater management systems at times of significant increase in surface water runoff due to rapid thawing when the risk of failure of erosion control measures is elevated. In such instances as remedial action is necessary, the Contractor shall repair any and all significant deficiencies in erosion control systems within two days. The Northampton Department of Public Works shall be notified of any significant failure of stormwater management systems or erosion and sediment control measures, and shall be notified of any release of pollutants to a water body (stream, brook, pond, etc.). The Contractor shall remove the sediment from behind the fence of the sedimentation control barrier when the accumulated sediment has reached one-half of the original installed height of the barrier. This project requires a NPDES General Permit for Stormwater Discharges from Constriction Activities. Contractor and Owner are responsible for finalizing a Stormwater Pollution Prevention Plan (SWPPP) and filing for the NDPES permit prior to the start of construction. All clearing, grading, drainage, construction, and development shall be conducted in strict accordance with the SWPPP. Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 2 Post-Construction Stormwater Management System Owner: The Community Builders, Inc. Property Management Department (617) 695-9595 Party Responsible for Operation & Maintenance: The Community Builders, Inc. Property Management Department (617) 695-9595 Inspection & Maintenance Schedule: 1) Deep-Sump Hooded Catch Basin Catch basins should be inspected at least two times per year and cleaned annually or more often if required. Oil and sediments should be removed and disposed of in accordance with local, state and federal guidelines and regulations. In the case of an oil or bulk pollutant release, the system must be cleaned immediately following the spill and the proper authorities notified. 2) Stormwater Treatment Chamber The stormwater treatment chamber should be inspected at regular intervals and maintained when necessary to ensure optimum performance. The system shall be inspected at least four times during the first year and at least twice per year thereafter. If sediment accumulates fast enough to require removal more than once per year, the inspection frequency shall be increased. The visual inspection should ascertain that the system components are in working order and that there are no blockages or obstructions in the inlet and separation screen. The inspection should also quantify the accumulation of hydrocarbons, trash, and sediment in the system. Measuring pollutant accumulation can be done with a calibrated dipstick, tape measure or other measuring instrument. The CDS system should be cleaned when the level of sediment has reached 75% of capacity in the isolated sump or when an appreciable level of hydrocarbons and trash has accumulated. If absorbent material is used, it should be replaced when significant discoloration has occurred. Performance will not be impacted until 100% of the sump capacity is exceeded; however, it is recommended that the system be cleaned prior to that for easier removal of sediment. The level of sediment is easily determined by measuring from finished grade down to the top of the sediment pile. To avoid underestimating the level of sediment in the chamber, the measuring device must be lowered to the top of the sediment pile carefully. Particles at the top of the pile typically offer less resistance to the end of the rod than consolidated particles toward the bottom of the pile. Once this measurement is recorded, it should be compared to the as-built drawing for the unit to determine whether the height of the sediment pile off the bottom of the sump floor exceeds 75% of the total height of isolated sump. Sediment shall be removed by a vacuum truck and disposed of in accordance with applicable regulations. Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 3 3) Rain Gardens & Sediment Forebays The rain gardens and sediment forebays shall be inspected at least four times per year for sediment accumulation and signs of damage or erosion. Sediment shall be removed any time it has accumulated more than ½”. At a minimum, sediment shall be removed annually. Failure of the system to drain (ponding 48 hours after the end of the storm) shall result in inspection and cleaning. Sediments shall be removed and disposed of in accordance with local, state and federal guidelines and regulations. Inspections shall identify any damage or signs of erosion within basin/swales, which shall be repaired immediately. It is recommended that sediment removal be performed after the completion of the spring snow melt. 4) Curb Inlets Curb inlets should be inspected at least two times per year and cleaned annually or more often if required. Vegetation growth occurring in the stone should be removed to ensure the inlet locations are free and clear and not hindering water from flowing from the street and into the swales. Any excessive sediment that had accumulated at the edge of the inlet location should also be removed and the stone should be reset to ensure proper flow. 5) Street Sweeping Regular street sweeping will prevent sediment from reaching the stormwater treatment chamber. This will extend the life of stormwater treatment elements, and will reduce the effort and expense of cleaning those element. Street sweeping is not required under this plan; however, sweeping twice per year (including after the spring snow melt) is recommended. Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 1 Stormwater Management System Operation & Maintenance Plan “Lot 20” 12-Unit Apartment Building (Map 38A, Lot 109) During Construction The Contractor shall be responsible for inspection and maintenance during construction. At all times, siltation fabric fencing, stakes and straw bales/wattles, sufficient to construct a sedimentation control barrier a minimum of 50 feet long, shall be stockpiled on the site in order to repair established barriers which may be damaged or breached. An inspection of all erosion control and stormwater management systems shall be conducted by the Contractor at least once a week and during all rain storms until the completion of construction. In case of any noted breach or failure, the Contractor shall immediately make appropriate repairs to any erosion control system and notify the engineer of any problems involving stormwater management systems. A rain storm shall be defined as any of the following: · A storm in which rain is predicted to last for twelve consecutive hours or more. · A storm for which a flash flood watch or warning is issued. · A single storm predicted to have a cumulative rainfall of greater than one-half inch. · A storm not meeting the previous three thresholds but which would mark a third consecutive day of measurable rainfall. The Contractor shall also inspect the erosion control and stormwater management systems at times of significant increase in surface water runoff due to rapid thawing when the risk of failure of erosion control measures is elevated. In such instances as remedial action is necessary, the Contractor shall repair any and all significant deficiencies in erosion control systems within two days. The Northampton Department of Public Works shall be notified of any significant failure of stormwater management systems or erosion and sediment control measures, and shall be notified of any release of pollutants to a water body (stream, brook, pond, etc.). The Contractor shall remove the sediment from behind the fence of the sedimentation control barrier when the accumulated sediment has reached one-half of the original installed height of the barrier. This project requires a NPDES General Permit for Stormwater Discharges from Constriction Activities. Contractor and Owner are responsible for finalizing a Stormwater Pollution Prevention Plan (SWPPP) and filing for the NDPES permit prior to the start of construction. All clearing, grading, drainage, construction, and development shall be conducted in strict accordance with the SWPPP. Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 2 Post-Construction Stormwater Management System Owner: The Community Builders, Inc. Property Management Department (617) 695-9595 Party Responsible for Operation & Maintenance: The Community Builders, Inc. Property Management Department (617) 695-9595 Inspection & Maintenance Schedule: 1) Rain Garden The rain garden shall be inspected at least four times per year for sediment accumulation and signs of damage or erosion. Sediment shall be removed any time it has accumulated more than ½”. At a minimum, sediment shall be removed annually. Failure of the system to drain (ponding 48 hours after the end of the storm) shall result in inspection and cleaning. Sediments shall be removed and disposed of in accordance with local, state and federal guidelines and regulations. Inspections shall identify any damage or signs of erosion within basin/swales, which shall be repaired immediately. It is recommended that sediment removal be performed after the completion of the spring snow melt. Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Appendix I – Storm Drain Sizing Calculations 4 Allen Place, Northampton, MA 01060 (413) 582-7000 bdg@berkshiredesign.com September 28, 2017 (Revised January 16, 2018) Doug McDonald Stormwater Manager Northampton DPW RE: Village Hill – The Community Builders Storm Drain Design Summary Dear Doug: The Berkshire Design Group (BDG) has the proposed storm drain system for The Community Builders Lot 13A project at Village Hill for conveyance of the 25-year storm. A table is enclosed showing the estimated flows through each proposed storm drain pipe during the 25-year storm. A summary of the calculations is described in this memo. Site hydrology was modeled utilizing the rational method, which provides simplified procedures for estimating peak runoff flow rates that are sufficiently accurate and conservative for small watersheds. The rational method is based on the following formula: = Where, = Flow Rate (cfs) = Runoff Coefficient = Rainfall Intensity (in/hr) = Area (ac) The site was broken into drainage areas, corresponding to each drainage inlet throughout the site. Surfaces within each drainage area were identified as pervious or impervious. Runoff coefficient of 0.20 was applied to vegetated areas; a runoff coefficient of 0.90 was applied to impervious areas. Rainfall intensity was based on Chapter 8 of the MassDOT Design Guide. Time of Concentration was conservatively assumed to be 5 minutes in all cases. For the 25-year storm, the Design Guide lists a rainfall intensity of 7.2 inches per hour. Based on the above calculations, a design flow rate was determined for the outlet pipe exiting each structure analyzed. The capacity of each outlet pipe was also determined by inputting the pipe diameter, length and slope into Manning’s formula. The design flow rate was then compared to the pipe capacity to check whether the pipe is designed to convey the 25-year flow rate. Each step of these calculations is tabulated in the attached spreadsheet. The Community Builders - Village HillStorm Drain Design Summary1/16/2018Drainage Area Total Area(sf) Impervious Area(sf) Runoff CoefficientA11,047 8,483 C(Impervious)0.9B10,982 8,298 C(Vegetated)0.2C32,271 24,698 D23,232 8,247 Rainfall Intensity (in/hr)E15,100 5,358 I7.2F59,214 20,477 G219,999 72,692 Manning "n" Valuen0.013 Structure ID Contributing Areas/Structures Total Area(sf) Impervious Area(sf) % ImperviousRunoff Coefficient 'C'RainfallIntensity 'I'(25-Year Storm)DrainageArea 'A'(acres)Flow RateQ=CIASize(in)Length(ft) Invert(Upstrm) Invert(Dwnstrm) Slope(%)Capacity(cfs)DesignCheckDI#1A11,047 8,483 77%0.747.20.251.35 1288224.00 223.10 1.0%3.61 OKDI#2A,B22,029 16,781 76%0.737.20.512.67 1268223.10 222.40 1.0%3.62 OKDI#3A,B,C54,300 41,479 76%0.737.21.256.59 18145222.40 220.90 1.0%10.71 OKDI#4D23,232 8,247 35%0.457.20.531.72 12158225.65 224.05 1.0%3.59 OKCB#5E15,100 5,358 35%0.457.20.351.12 1216225.65 225.00 4.1%7.20 OKCB#6F59,214 20,477 35%0.447.21.364.33 1232225.65 225.00 2.0%5.09 OKDMH#7E,F74,314 25,835 35%0.447.21.715.45 1891224.90 223.00 2.1%15.22 OKDMH#8A,B,C,D,E,F151,846 75,561 50%0.557.23.4913.76 18279222.90 199.00 8.6%30.83 OKSTC#9A,B,C,D,E,F,G371,845 148,253 40%0.487.28.5429.45 24145195.00 192.00 2.1%32.63 OKDI#5H12,523 7,803 62%0.647.20.291.32 12145195.00 192.00 2.1%5.14 OKOutlet Pipe Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Appendix J – Impervious Area Tabulation Summary ENCLOSURE 1: IMPERVIOUS AREA MAPS ENCLOSURE 2: EXCERPTS FROM 2007 STORMWATER MANAGEMENT REPORT Village Hill – The Community Builders September 28, 2017 (Revised January 16, 2018) Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Appendix K – Stormwater Hydrology Calculations for Runoff toward Pecoy Homes Development TCB-E Lot 13A Site TCB-P Lot 13A Site PCY-E Pecoy Development PCY-P Pecoy Development Routing Diagram for Village Hill - TCB - to Pecoy Prepared by Microsoft, Printed 1/16/2018 HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Subcat Reach Pond Link Type III 24-hr 2-yr Rainfall=3.00"Village Hill - TCB - to Pecoy Printed 1/16/2018Prepared by Microsoft Page 2HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=95,446 sf 1.89% Impervious Runoff Depth>0.81"Subcatchment TCB-E: Lot 13A Site Tc=6.0 min CN=72 Runoff=1.85 cfs 0.147 af Runoff Area=62,057 sf 17.03% Impervious Runoff Depth>1.07"Subcatchment TCB-P: Lot 13A Site Tc=6.0 min CN=77 Runoff=1.70 cfs 0.127 af Inflow=1.85 cfs 0.147 afReach PCY-E: Pecoy Development Outflow=1.85 cfs 0.147 af Inflow=1.70 cfs 0.127 afReach PCY-P: Pecoy Development Outflow=1.70 cfs 0.127 af Type III 24-hr 2-yr Rainfall=3.00"Village Hill - TCB - to Pecoy Printed 1/16/2018Prepared by Microsoft Page 3HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Subcatchment TCB-E: Lot 13A Site Area in NW corner of existing site Runoff = 1.85 cfs @ 12.10 hrs, Volume= 0.147 af, Depth> 0.81" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-yr Rainfall=3.00" Area (sf) CN Description * 1,804 98 Pavement & Roof 56,051 70 Woods, Good, HSG C 37,591 74 >75% Grass cover, Good, HSG C 95,446 72 Weighted Average 93,642 98.11% Pervious Area 1,804 1.89% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment TCB-P: Lot 13A Site Area in NW corner of existing site Runoff = 1.70 cfs @ 12.10 hrs, Volume= 0.127 af, Depth> 1.07" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-yr Rainfall=3.00" Area (sf) CN Description * 6,617 98 Pavement & Roof 6,082 90 1/8 acre lots, 65% imp, HSG C 11,517 70 Woods, Good, HSG C 37,841 74 >75% Grass cover, Good, HSG C 62,057 77 Weighted Average 51,487 82.97% Pervious Area 10,570 17.03% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Reach PCY-E: Pecoy Development Inflow Area = 2.191 ac, 1.89% Impervious, Inflow Depth > 0.81" for 2-yr event Inflow = 1.85 cfs @ 12.10 hrs, Volume= 0.147 af Outflow = 1.85 cfs @ 12.10 hrs, Volume= 0.147 af, Atten= 0%, Lag= 0.0 min Type III 24-hr 2-yr Rainfall=3.00"Village Hill - TCB - to Pecoy Printed 1/16/2018Prepared by Microsoft Page 4HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Reach PCY-P: Pecoy Development Inflow Area = 1.425 ac, 17.03% Impervious, Inflow Depth > 1.07" for 2-yr event Inflow = 1.70 cfs @ 12.10 hrs, Volume= 0.127 af Outflow = 1.70 cfs @ 12.10 hrs, Volume= 0.127 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.50"Village Hill - TCB - to Pecoy Printed 1/16/2018Prepared by Microsoft Page 5HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=95,446 sf 1.89% Impervious Runoff Depth>1.82"Subcatchment TCB-E: Lot 13A Site Tc=6.0 min CN=72 Runoff=4.51 cfs 0.332 af Runoff Area=62,057 sf 17.03% Impervious Runoff Depth>2.21"Subcatchment TCB-P: Lot 13A Site Tc=6.0 min CN=77 Runoff=3.61 cfs 0.262 af Inflow=4.51 cfs 0.332 afReach PCY-E: Pecoy Development Outflow=4.51 cfs 0.332 af Inflow=3.61 cfs 0.262 afReach PCY-P: Pecoy Development Outflow=3.61 cfs 0.262 af Type III 24-hr 10-yr Rainfall=4.50"Village Hill - TCB - to Pecoy Printed 1/16/2018Prepared by Microsoft Page 6HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Subcatchment TCB-E: Lot 13A Site Area in NW corner of existing site Runoff = 4.51 cfs @ 12.10 hrs, Volume= 0.332 af, Depth> 1.82" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.50" Area (sf) CN Description * 1,804 98 Pavement & Roof 56,051 70 Woods, Good, HSG C 37,591 74 >75% Grass cover, Good, HSG C 95,446 72 Weighted Average 93,642 98.11% Pervious Area 1,804 1.89% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment TCB-P: Lot 13A Site Area in NW corner of existing site Runoff = 3.61 cfs @ 12.09 hrs, Volume= 0.262 af, Depth> 2.21" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.50" Area (sf) CN Description * 6,617 98 Pavement & Roof 6,082 90 1/8 acre lots, 65% imp, HSG C 11,517 70 Woods, Good, HSG C 37,841 74 >75% Grass cover, Good, HSG C 62,057 77 Weighted Average 51,487 82.97% Pervious Area 10,570 17.03% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Reach PCY-E: Pecoy Development Inflow Area = 2.191 ac, 1.89% Impervious, Inflow Depth > 1.82" for 10-yr event Inflow = 4.51 cfs @ 12.10 hrs, Volume= 0.332 af Outflow = 4.51 cfs @ 12.10 hrs, Volume= 0.332 af, Atten= 0%, Lag= 0.0 min Type III 24-hr 10-yr Rainfall=4.50"Village Hill - TCB - to Pecoy Printed 1/16/2018Prepared by Microsoft Page 7HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Reach PCY-P: Pecoy Development Inflow Area = 1.425 ac, 17.03% Impervious, Inflow Depth > 2.21" for 10-yr event Inflow = 3.61 cfs @ 12.09 hrs, Volume= 0.262 af Outflow = 3.61 cfs @ 12.09 hrs, Volume= 0.262 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-yr Rainfall=5.25"Village Hill - TCB - to Pecoy Printed 1/16/2018Prepared by Microsoft Page 8HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=95,446 sf 1.89% Impervious Runoff Depth>2.39"Subcatchment TCB-E: Lot 13A Site Tc=6.0 min CN=72 Runoff=5.99 cfs 0.436 af Runoff Area=62,057 sf 17.03% Impervious Runoff Depth>2.83"Subcatchment TCB-P: Lot 13A Site Tc=6.0 min CN=77 Runoff=4.64 cfs 0.336 af Inflow=5.99 cfs 0.436 afReach PCY-E: Pecoy Development Outflow=5.99 cfs 0.436 af Inflow=4.64 cfs 0.336 afReach PCY-P: Pecoy Development Outflow=4.64 cfs 0.336 af Type III 24-hr 25-yr Rainfall=5.25"Village Hill - TCB - to Pecoy Printed 1/16/2018Prepared by Microsoft Page 9HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Subcatchment TCB-E: Lot 13A Site Area in NW corner of existing site Runoff = 5.99 cfs @ 12.10 hrs, Volume= 0.436 af, Depth> 2.39" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-yr Rainfall=5.25" Area (sf) CN Description * 1,804 98 Pavement & Roof 56,051 70 Woods, Good, HSG C 37,591 74 >75% Grass cover, Good, HSG C 95,446 72 Weighted Average 93,642 98.11% Pervious Area 1,804 1.89% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment TCB-P: Lot 13A Site Area in NW corner of existing site Runoff = 4.64 cfs @ 12.09 hrs, Volume= 0.336 af, Depth> 2.83" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-yr Rainfall=5.25" Area (sf) CN Description * 6,617 98 Pavement & Roof 6,082 90 1/8 acre lots, 65% imp, HSG C 11,517 70 Woods, Good, HSG C 37,841 74 >75% Grass cover, Good, HSG C 62,057 77 Weighted Average 51,487 82.97% Pervious Area 10,570 17.03% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Reach PCY-E: Pecoy Development Inflow Area = 2.191 ac, 1.89% Impervious, Inflow Depth > 2.39" for 25-yr event Inflow = 5.99 cfs @ 12.10 hrs, Volume= 0.436 af Outflow = 5.99 cfs @ 12.10 hrs, Volume= 0.436 af, Atten= 0%, Lag= 0.0 min Type III 24-hr 25-yr Rainfall=5.25"Village Hill - TCB - to Pecoy Printed 1/16/2018Prepared by Microsoft Page 10HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Reach PCY-P: Pecoy Development Inflow Area = 1.425 ac, 17.03% Impervious, Inflow Depth > 2.83" for 25-yr event Inflow = 4.64 cfs @ 12.09 hrs, Volume= 0.336 af Outflow = 4.64 cfs @ 12.09 hrs, Volume= 0.336 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=7.00"Village Hill - TCB - to Pecoy Printed 1/16/2018Prepared by Microsoft Page 11HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=95,446 sf 1.89% Impervious Runoff Depth>3.83"Subcatchment TCB-E: Lot 13A Site Tc=6.0 min CN=72 Runoff=9.65 cfs 0.699 af Runoff Area=62,057 sf 17.03% Impervious Runoff Depth>4.36"Subcatchment TCB-P: Lot 13A Site Tc=6.0 min CN=77 Runoff=7.12 cfs 0.518 af Inflow=9.65 cfs 0.699 afReach PCY-E: Pecoy Development Outflow=9.65 cfs 0.699 af Inflow=7.12 cfs 0.518 afReach PCY-P: Pecoy Development Outflow=7.12 cfs 0.518 af Type III 24-hr 100-yr Rainfall=7.00"Village Hill - TCB - to Pecoy Printed 1/16/2018Prepared by Microsoft Page 12HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Subcatchment TCB-E: Lot 13A Site Area in NW corner of existing site Runoff = 9.65 cfs @ 12.09 hrs, Volume= 0.699 af, Depth> 3.83" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=7.00" Area (sf) CN Description * 1,804 98 Pavement & Roof 56,051 70 Woods, Good, HSG C 37,591 74 >75% Grass cover, Good, HSG C 95,446 72 Weighted Average 93,642 98.11% Pervious Area 1,804 1.89% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment TCB-P: Lot 13A Site Area in NW corner of existing site Runoff = 7.12 cfs @ 12.09 hrs, Volume= 0.518 af, Depth> 4.36" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=7.00" Area (sf) CN Description * 6,617 98 Pavement & Roof 6,082 90 1/8 acre lots, 65% imp, HSG C 11,517 70 Woods, Good, HSG C 37,841 74 >75% Grass cover, Good, HSG C 62,057 77 Weighted Average 51,487 82.97% Pervious Area 10,570 17.03% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Reach PCY-E: Pecoy Development Inflow Area = 2.191 ac, 1.89% Impervious, Inflow Depth > 3.83" for 100-yr event Inflow = 9.65 cfs @ 12.09 hrs, Volume= 0.699 af Outflow = 9.65 cfs @ 12.09 hrs, Volume= 0.699 af, Atten= 0%, Lag= 0.0 min Type III 24-hr 100-yr Rainfall=7.00"Village Hill - TCB - to Pecoy Printed 1/16/2018Prepared by Microsoft Page 13HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Reach PCY-P: Pecoy Development Inflow Area = 1.425 ac, 17.03% Impervious, Inflow Depth > 4.36" for 100-yr event Inflow = 7.12 cfs @ 12.09 hrs, Volume= 0.518 af Outflow = 7.12 cfs @ 12.09 hrs, Volume= 0.518 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs