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2015-05-28 Barrett St Drainage Report
Stormwater Management Report Prepared by: ---The ~~i Berkshire Design Group, Inc. 4 Allen Place, Northampton, Massachusetts 01060 for Sunwood Green 95 Barrett Street Northampton, MA May 28, 2015 Sunwood Green – 95 Barrett Street May 28, 2015 Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page i Table of Contents I. Introduction ........................................................................................................................1 II. Existing Conditions ..............................................................................................................2 III. Proposed Conditions ...........................................................................................................3 IV. Calculations and Design .......................................................................................................4 V. MADEP Stormwater Standards Compliance..........................................................................6 VI. Summary .................................................................................. Error! Bookmark not defined. Figures Figure 1 Project Location Figure 2 Existing Conditions Figure 3 Drainage Plan Figure 4 Existing Hydrology Figure 5 Proposed Hydrology Appendix Appendix A NRCS Soil Report Appendix B Subsurface Investigation Results Appendix C Stormwater Hydrology Calculations Appendix D Water Quality Calculations Appendix E Stormwater Management System – Operation & Maintenance Plan Appendix F MassDEP Stormwater Checklist Referenced Documents Plan Set Site Plan for Sunwood Green – Site Plan Review Set Sunwood Green – 95 Barrett Street May 28, 2015 Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 1 Sunwood Builders is proposing the construction of a new residential townhouse condominium development at 95 Barrett Street in 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 will construct 12 new residential townhouse buildings, in addition to an existing single-family house that will remain and be expanded. The project is located on the north side of Barrett Street, as shown in Figure 1. The work includes construction of the proposed buildings, as well as associated site, utility and stormwater improvements. The existing house sits on a local high point, near the center of the parcel, though the larger neighborhood generally slopes from west to east. The front portion of the site (between the existing house and Barrett Street) slopes gently toward the street. The larger rear portion of the site slopes toward an intermittent stream running along the north property line. The existing intermittent stream appears to have a watershed that includes the Jackson Street School and the properties immediately surrounding the school. The stream is captured by a double- catch-basin inlet just beyond the limits of the site, on the Hathaway Farms Apartments property to the north and east of the site. Records indicate that the stream is carried by a culvert to Barrett Street Brook to the east. An existing bordering vegetated wetland is located along the stream. The wetland has been flagged and is shown on the project plan sheets. Barrett Street contains no stormwater infrastructure in the immediate vicinity of the site. Stormwater runs along the gutter line down to a discharge point where the street crosses over Barrett Street Brook. The site is predominantly a mix of lawn and minimally-maintained grass. The edges of the rear portion of the site, including most of the wetland area consist of brush and lightly wooded areas. Existing impervious area is limited the existing house, a gravel driveway and small parking area adjacent to the house. Soil Data Observation of the site, along with boring and test pit data confirms that the site is generally underlain by sandy loam and silt loam with some clay. Seasonal high groundwater was estimated to be 20 to 36 inches below the surface across the site. The on-site soil evaluation concluded that the permeability of the soils is low. NRCS Soil Survey The NRCS Soil Survey of Hampshire County, Massachusetts, Central Part Report identifies the following classifications of soils at the site. · (30A) Raynham silt loam (83% of Site) Hydrologic Group: C/D Sunwood Green – 95 Barrett Street May 28, 2015 Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 2 · (749B) Windsor loamy sand (17% of Site) Hydrologic Group: A The NRCS Soil Map illustrating these results is shown in Figure 2. An NRCS Soil Report for the site is included in Appendix A. Subsurface Exploration A total of 5 test pits were conducted at the site in order to classify existing soils and determine the relevant engineering properties. A summary of these explorations is included in Appendix B. In general, soils in the rear portion of the site were found to be fine sandy loam. Soils in the front portion of the site were found to be fill underlain by silt loam with clay. Summary Based on the data from the subsurface exploration, this report concludes that the entire site is most appropriately classified as Hydrologic Soil Group (HSG) C, notwithstanding the results of the NRCS Soil Survey. In order to provide for a conservative analysis and design, the proposed stormwater management system is designed based on all site soils being classified as HSG C, due to the greater potential for runoff from the lower-permeability soils. Based on the low-permeability of the soils and very high groundwater conditions, it was determined that the site is unsuitable for infiltration structures or groundwater recharge. Site Limits Site limits were delineated for the purpose of establishing drainage areas within the site. Site limits were based on property lines, and are shown in Figure 4. Regulated Areas An existing intermittent stream and the associated bordering vegetated wetland are located along the north edge of the site. The limits of the flagged wetland and 100-foot buffer are shown on the Existing Conditions Plan in Figure 2. II. Existing Conditions An Existing Conditions Plan is shown on Figure 2. Drainage Areas Three drainage areas were identified within the existing site. The drainage areas (labeled E1 through E3) are shown on the Existing Drainage Area Plan in Figure 4. A brief description of each drainage area follows. Area E-1 Area E-1 includes the rear portion of the site that drains into the stream at the north edge of the site. Sunwood Green – 95 Barrett Street May 28, 2015 Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 3 Area E-2 Area E-2 includes parts of the site that drain to Barrett Street, and are collected in the gutter line. Area E-3 Area E-3 includes the portion of the site that drain to the abutting property to the east. Because the existing stream to the north is collected by an inlet immediately to the north and east of the site, runoff from Area E-3 is not collected by the stream. A field investigation suggests that this runoff is eventually collected by the storm drainage system owned by the Hathaway Farms Apartments. Overall Records research and field investigation shows that all runoff from the site is ultimately discharged to Barrett Street Brook, located approximately 700’ east of the site. III. Proposed Conditions The proposed conditions are shown on the Site Plan in Figure 4. The proposed project will construct 12 additional residential units (in addition to the existing house that will be retained and expanded), two garage structures and a private access street with parking. The center of the site will be community lawn space with landscaping and a recreational patio. Land between the proposed buildings and existing wetland will be left totally unmaintained and allowed to fill in with heavy brush and woodland. Green space to the front of the site will be lawn. Extensive landscaping is proposed for the site, as shown in the project plans. The stormwater management system includes a stone diaphragm drain, stormwater treatment chamber (Stormceptor or equivalent), an underground pipe-and-stone detention basin, and a level- lip spreader outlet. The system has been designed to reduce peak runoff and improve water quality by removing suspended solids. The proposed detention basin is designed to attenuate the 2, 10, and 100-year storms, and to produce a reduction in peak runoff from the site. The proposed stone diaphragm drain will run along the edge of the central green. This drain is designed to collect stormwater from the road and remove a significant amount of suspended solids, while avoiding the use of traditional curb-and-inlet drainage. The proposed stormwater treatment chamber will provide additional water quality improvement, and safeguard the detention basin against clogging. Groundwater recharge was considered on the site; however, the low permeability of soils and high groundwater elevation identified during the subsurface investigation would precludes any significant level of infiltration. While no formal groundwater recharge system is proposed, the detention basin is a permeable stone-and-perforated-pipe system and is expected to provide some recharge during dry seasons, to the extent allowed by surrounding soils. Drainage Areas The proposed site is delineated into four drainage areas, identified as areas P1 through P4, and are shown on the Proposed Drainage Area Plan in Figure 5. Sunwood Green – 95 Barrett Street May 28, 2015 Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 4 Area P-1 Area P-1 includes the portion of the site that will continue to drain directly to the stream at the north edge of the site. This drainage area includes a portion of raised timber deck and lawn; however, no impervious area is included in this drainage area. Area P-2 Area P-2 includes portions of the site that drain toward Barrett Street. Area P-3 Area P-3 includes the central portion of the site that is collected by the stormwater management system. This area includes all building roofs and all pavement, except for the front part of the site that drains directly to Barrett Street. Area P-4 Area P-4 includes the east edge of the site that will continue to drain to the abutting property to the east. 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 the appendices. 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. As noted under “Soil Data” in Section I – Introduction, the soil hydrologic group identified by the NRCS Soil Survey were not consistent with the results of the subsurface investigation. For this reason, the calculations were performed based on soil conditions actually observed during the subsurface investigation. Watershed subcatchment areas, runoff coefficients and watercourse slopes are based on survey information. Calculations were performed for the 2-, 10-, and 100-year frequency storms under existing and proposed conditions. The results of the calculations are presented in Table 1 below. Appendix C presents the Hydrocad calculations. Sunwood Green – 95 Barrett Street May 28, 2015 Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 5 Table 1. Runoff Summary Table Condition & Point of Analysis 2-Year Storm 3.00” 10-Year Storm 4.50” 100-Year Storm 6.50” Peak Flow Rate(cfs) Peak Flow Rate(cfs) Peak Flow Rate(cfs) Existing (CP1)* 0.79 1.85 3.38 Proposed (CP1)* 0.76 1.81 3.38 Existing (CP2)* 0.78 1.66 2.87 Proposed (CP2)* 0.77 1.43 2.30 Existing (CP3)* 0.18 0.46 0.86 Proposed (CP3)* 0.15 0.33 0.59 *Names in parentheses refer to HydroCad model and calculations. Table 2. Total Runoff from Site Condition & Point of Analysis 2-Year Storm 3.00” 10-Year Storm 4.50” 100-Year Storm 6.50” Peak Flow Rate(cfs) Peak Flow Rate(cfs) Peak Flow Rate(cfs) Existing (CPT)* 1.75 3.97 7.12 Proposed (CPT)* 1.64 3.27 6.17 *Names in parentheses refer to HydroCad model and calculations. Water Quality The proposed stormwater management system is designed to remove at least 80% of the average annual post-construction load of Total Suspended Solids (TSS), as well as oil and grease deposited on the proposed roadway, driveway and parking areas that are captured by the proposed stormwater management system. While runoff discharged from the site to the north and east will be treated in order to remove greater than 80% of TSS, this level of treatment is not achieved in runoff directed to Barrett Street. This runoff is produced by the proposed driveway entrance. This pavement cannot be eliminated, and site grading cannot be changed to direct this runoff inward (the intersection with the street is near the low point of the site. Multiple schemes for providing some level of water quality treatment were considered, including vegetated filter strips, permeable pavement, rain gardens, sediment forebays and proprietary treatment structures. The combination of low-permeability soils, high Sunwood Green – 95 Barrett Street May 28, 2015 Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 6 groundwater and lack of drainage infrastructure in Barrett Street make any of these treatment BMPs impractical, if not impossible. The Owner has expressed a willingness to consider an off-site mitigation option in order to achieve TSS removal. As one example, a stormwater treatment chamber located downstream of the site, which would capture a larger drainage area, could potentially provide a more significant water- quality improvement to the City than could be provided from on-site treatment. Low-Impact Design Elements The proposed stormwater management plan includes features that convey stormwater through natural-scale flow patterns or capture stormwater temporarily in order to promote infiltration for groundwater recharge. The proposed grading and drainage plan calls for most of the paved areas to be directed to a “country drainage” style stone diaphragm drain that will trap suspended solids, slow velocities during low-runoff events, reduce water temperature, and promote groundwater recharge to the extent that site soils will allow. More extensive LID design elements were not practical on this site due to poor soil conditions and high groundwater elevations that are not conducive to significant infiltration. BMP Treatment Trains Discharge to Stream Stormwater released toward the existing stream at the north edge of the site (see Figure 3) receives runoff from Drainage Area P-3. All non-roof areas are directed to a stone diaphragm drain and/or raised-rim inlets, as well as a stormwater treatment chamber. TSS removal for this treatment train is estimated at 86%, and calculations are shown in Appendix D. There is one stormwater inflow that enters the system between the stormwater treatment chamber and the outlet. This connection conveys only runoff from the roofs of the proposed buildings at the east edge of the site. Because this inflow is made up entirely of clean roof runoff, it is omitted from the water quality calculations. Discharge to Barrett Street As discussed above, the design team was unable to identify a practical means of providing water quality treatment for runoff to Barrett Street (Drainage Area P-2). Overland Flow Stormwater from Drainage Areas P-1 and P-3 exit the site via overland flow to the north and east of the site. These areas do not include impervious area. These areas do include approximately 1,600 sf of raised timber deck, which is not expected to generate suspended solids. V. MADEP Stormwater Standards Compliance The following section details how the project will meet the DEP Stormwater Management Policy’s ten stormwater management standards. Sunwood Green – 95 Barrett Street May 28, 2015 Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 7 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. Pavement runoff will be collected by a stone diaphragm drain and raised-rim inlets. The stone diaphragm will provide infiltration of runoff to the extent that site conditions allow. Low-impact design is discussed further in Section IV. Standard 1 - Untreated Stormwater Discharge The proposed stormwater management system includes one new discharge to wetland areas. The new conveyance is located at the northeast corner of the site, and discharges stormwater from Drainage Area P-2. All non-roof runoff discharged by this outlet is directed to a stormwater treatment chamber, and the net TSS removal for runoff from impervious areas is 86%. TSS removal calculations are included in Appendix D. The soil below this outlet will be protected with a level spreader, designed in compliance with the Massachusetts Stormwater Handbook. The level-spreader outlet to toward the stream at the north edge of the site was included in the HydroCAD model. The model predicts an outlet velocity of 0.53 fps for the 2-year storm and 0.85 fps for the 100-year storm. These velocities are well below the “permissible velocity” that is deemed acceptable by the Stormwater Handbook. The remaining discharge points are either paved (Barrett Street) or receive small amounts of runoff that sheet flow across grass and brush. None of these outlets are expected to be vulnerable to erosion. 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 structures are not included in the proposed stormwater management system. The site was analyzed for locations that would be conducive to groundwater recharge. Five locations were selected for subsurface investigation, in order to determine suitable locations for groundwater recharge structures. Results of the subsurface investigation found low-permeability soils and very high seasonal groundwater, which are conditions not conducive to an infiltration system. Standard 3 requires infiltration be included in the proposed stormwater management system for sites where soils of hydrologic soil group types A or B are present. The NRCS Soil Survey shows that the rear portion of the site (approximately 75%) are classified as group C soils, which was corroborated by the on-site subsurface investigation. The Soil Survey classified remaining portion of the site (nearest to Barrett Street) as group A soils; however, the subsurface investigation found soils in this area to consist of silt loam and clay. Sunwood Green – 95 Barrett Street May 28, 2015 Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 8 Based on these results, the site soils are more realistically classified as group C throughout the site. For sites where group A and B soils are not present, Standard 3 requires only that groundwater recharge be included to the greatest extent practicable. The proposed stone diaphragm drain and underground detention basin are “open” systems, consisting of perforated pipe and stone. While the infiltration rate is not estimated here, it is anticipated that these measures will provide some level of groundwater recharge. Based on the results of the subsurface investigation, no additional infiltration is practicable at this site. Standard 4 – Water Quality The proposed site directs runoff from impervious surfaces to two separate outlet points. The BMP treatment train upstream of the outlet to the existing stream at the north edge of the site is estimated to remove 86% of TSS. Due to site conditions, it is not possible to provide treatment for runoff discharged to Barrett Street. Because of this, the proposed plan does not fully comply with Standard 4. The Owner has expressed a willingness to consider off-site mitigation, which is potentially more beneficial to the City’s stormwater system than on-site treatment, in order to comply with this Standard. All other runoff from the site is directed via sheet flow overland across vegetated areas. None of this runoff originates from impervious surfaces. Further details of the water quality design are included under “Water Quality” in Section IV, above. TSS removal calculations for each proposed outlet are included in Appendix D. 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 project site does not discharge to critical areas as defined in MADEP Stormwater Policy Handbook. Standard 7 - Redevelopment Projects This project is not a redevelopment project. Standard 8 - Erosion/Sediment Control A proposed Erosion & Sediment Control Plan has been developed, and is shown in the plan set titled, Smith College Paradise Road Housing – Permit Plans, dated 4/24/2014. 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 E. It includes general controls for construction and long term maintenance of the stormwater management system. Sunwood Green – 95 Barrett Street May 28, 2015 Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 9 Standard 10 – Prohibition of Illicit Discharges No Illicit Discharge Compliance Statement is included with this report however one will be submitted prior to the discharge of any stormwater to post-construction BMPs. Sunwood Green – 95 Barrett Street Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. FIGURES Checked By: Drawn By: Revisions Scale: Date:Sheet Number This drawing is not intended nor shall it be used forconstruction purposes unless the signed professional seal of aregistered landscape architect, civil engineer or land surveyoremployed by The Berkshire Design Group, Inc. is affixed above. Landscape ArchitectureCivil EngineeringPlanning Berkshire Group, Inc.Design The Do not scale drawing for quantity take-offs or construction. Usewritten dimensions only. If dimensions are incomplete, contactThe Berkshire Design Group Inc. for clarification. Land Surveying Copyright The Berkshire Design Group, Inc.This drawing and all of its contents are the express property ofThe Berkshire Design Group, Inc., and shall not be copied orused in any way without the written consent of The BerkshireDesign Group, Inc. c SUNWOOD GREEN 95 BARRETT STREET NORTHAMPTON, MA LOCATION PLAN MAY 28, 2015 1"=20' CMC MBD FIG1 #99 XXX X X X X X X X X X X X X X 28" 30" 36" 18"18" 18" X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X BARRET STREET DOES NOT CONTAIN STORM DRAINS OR STRUCTURES APPROX. CENTERLINE EXISTING INTERMITTENT STREAM APPROX. LINE OF EXISTING TREES & HEAVY BRUSH (TYP.) LIMIT OF FLAGGED BORDERING VEGETATED WETLAND EXISTING CONIFEROUS TREE (TYP.) EXISTING DECIDUOUS TREE (TYP.) EXISTING 4' CHAIN-LINK FENCE COMBINATION OF LAWN AND SEASONALLY-MOWED FIELD STREAM DISCHARGES TO INLET ON ABUTTING PROPERTY TO THE NORTHEAST AND FLOWS THROUGH EXISTING STORM DRAIN TO BARRET STREET MARSH OUTLET STREAM Checked By: Drawn By: Revisions Scale: Date:Sheet Number This drawing is not intended nor shall it be used forconstruction purposes unless the signed professional seal of aregistered landscape architect, civil engineer or land surveyoremployed by The Berkshire Design Group, Inc. is affixed above. Landscape ArchitectureCivil EngineeringPlanning Berkshire Group, Inc.Design The Do not scale drawing for quantity take-offs or construction. Usewritten dimensions only. If dimensions are incomplete, contactThe Berkshire Design Group Inc. for clarification. Land Surveying Copyright The Berkshire Design Group, Inc.This drawing and all of its contents are the express property ofThe Berkshire Design Group, Inc., and shall not be copied orused in any way without the written consent of The BerkshireDesign Group, Inc. c SUNWOOD GREEN 95 BARRETT STREET NORTHAMPTON, MA STORMWATER EXISTING CONDITIONS MAY 28, 2015 AS SHOWN CMC MBD FIG2 NOT FOR C O N S T R U C T I O N #99 XXX X X X X X X X X X X X X X 28" 30" 36" 18"18" 18" X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D LEVEL LIP SPREADER OUTLET CONTROL STRUCTURE STONE DIAPHRAGM DRAIN FOR COLLECTION & TREATMENT OF ROADWAY RUNOFF PERFORATED PIPE-IN-STONE DETENTION BASIN GR A S S SW A L E YARD DRAIN YD1 WITH RAISED RIM DRAIN MANHOLE DMH1 DRAIN MANHOLE DMH2 YARD DRAIN YD2 WITH RAISED RIM STORMWATER TREATMENT CHAMBER (STORMCEPTOR OR EQUAL) HDPE STORM DRAIN (TYP.) Checked By: Drawn By: Revisions Scale: Date:Sheet Number This drawing is not intended nor shall it be used forconstruction purposes unless the signed professional seal of aregistered landscape architect, civil engineer or land surveyoremployed by The Berkshire Design Group, Inc. is affixed above. Landscape ArchitectureCivil EngineeringPlanning Berkshire Group, Inc.Design The Do not scale drawing for quantity take-offs or construction. Usewritten dimensions only. If dimensions are incomplete, contactThe Berkshire Design Group Inc. for clarification. Land Surveying Copyright The Berkshire Design Group, Inc.This drawing and all of its contents are the express property ofThe Berkshire Design Group, Inc., and shall not be copied orused in any way without the written consent of The BerkshireDesign Group, Inc. c SUNWOOD GREEN 95 BARRETT STREET NORTHAMPTON, MA NOT FOR C O N S T R U C T I O N DRAINAGE PLAN MAY 28, 2015 AS SHOWN CMC MBD FIG3 #99 X X X X X X X X 28" 30" 36" 18"18" 18" X X X X X X X X X X X X X X X X X X X X X X DRAINAGE AREA E-1 TOTAL: 36,694 SF IMPERVIOUS: 0 SF GRAVEL: 106 SF GRASS: 33,117 SF BRUSH: 3,471 SF DRAINAGE AREA E-2 TOTAL: 27,890 SF IMPERVIOUS: 814 SF GRAVEL: 2,871 SF GRASS: 24,205 SF DRAINAGE AREA E-3 TOTAL: 9,949 SF IMPERVIOUS: 0 SF GRAVEL: 0 SF GRASS: 6,289 SF BRUSH: 3,660 SF IMPERVIOUS GRAVEL BRUSH Checked By: Drawn By: Revisions Scale: Date:Sheet Number This drawing is not intended nor shall it be used forconstruction purposes unless the signed professional seal of aregistered landscape architect, civil engineer or land surveyoremployed by The Berkshire Design Group, Inc. is affixed above. Landscape ArchitectureCivil EngineeringPlanning Berkshire Group, Inc.Design The Do not scale drawing for quantity take-offs or construction. Usewritten dimensions only. If dimensions are incomplete, contactThe Berkshire Design Group Inc. for clarification. Land Surveying Copyright The Berkshire Design Group, Inc.This drawing and all of its contents are the express property ofThe Berkshire Design Group, Inc., and shall not be copied orused in any way without the written consent of The BerkshireDesign Group, Inc. c SUNWOOD GREEN 95 BARRETT STREET NORTHAMPTON, MA EXISTING HYDROLOGY MAY 28, 2015 AS SHOWN CMC MBD FIG4 D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D DD D D D D D D D D D D D D D D DD D D D D D D D D D D D D D D DDD D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D DRAINAGE AREA P-4 TOTAL: 6,085 SF DECK.: 936 SF GRASS: 3,886 SF BRUSH: 1,263 SF IMPERVIOUS RAISED DECK BRUSH THIS SEGMENT OF ROOF IS INCLUDED IN DRAINAGE AREA P-3 DRAINAGE AREA P-1 TOTAL: 7,922 SF IMPERV: 92 SF DECK: 689 SF GRASS: 3,318 SF BRUSH: 3,823 SF Checked By: Drawn By: Revisions Scale: Date:Sheet Number This drawing is not intended nor shall it be used forconstruction purposes unless the signed professional seal of aregistered landscape architect, civil engineer or land surveyoremployed by The Berkshire Design Group, Inc. is affixed above. Landscape ArchitectureCivil EngineeringPlanning Berkshire Group, Inc.Design The Do not scale drawing for quantity take-offs or construction. Usewritten dimensions only. If dimensions are incomplete, contactThe Berkshire Design Group Inc. for clarification. Land Surveying Copyright The Berkshire Design Group, Inc.This drawing and all of its contents are the express property ofThe Berkshire Design Group, Inc., and shall not be copied orused in any way without the written consent of The BerkshireDesign Group, Inc. c SUNWOOD GREEN 95 BARRETT STREET NORTHAMPTON, MA PROPOSED HYDROLOGY MAY 14, 2015 1"=20' CMC MBD FIG5 Sunwood Green – 95 Barrett Street 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 Natural Resources Conservation Service May 14, 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........................................................................................10 Hampshire County, Massachusetts, Central Part...........................................12 30A—Raynham silt loam, 0 to 3 percent slopes.........................................12 741A—Amostown-Windsor silty substratum-Urban land complex, 0 to 3 percent slopes.......................................................................................13 749B—Windsor loamy sand, silty substratum, 3 to 8 percent slopes.........15 References............................................................................................................17 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 46 8 9 5 2 0 46 8 9 5 4 0 46 8 9 5 6 0 46 8 9 5 8 0 46 8 9 6 0 0 46 8 9 6 2 0 46 8 9 6 4 0 46 8 9 6 6 0 46 8 9 6 8 0 46 8 9 7 0 0 46 8 9 5 2 0 46 8 9 5 4 0 46 8 9 5 6 0 46 8 9 5 8 0 46 8 9 6 0 0 46 8 9 6 2 0 46 8 9 6 4 0 46 8 9 6 6 0 46 8 9 6 8 0 46 8 9 7 0 0 694220 694240 694260 694280 694300 694320 694340 694360 694240 694260 694280 694300 694320 694340 694360 42° 20' 7'' N 72 ° 3 8 ' 3 3 ' ' W 42° 20' 7'' N 72 ° 3 8 ' 2 6 ' ' W 42° 20' 1'' N 72 ° 3 8 ' 3 3 ' ' W 42° 20' 1'' N 72 ° 3 8 ' 2 6 ' ' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 18N WGS84 04080160240Feet 010204060Meters Map Scale: 1:913 if printed on A portrait (8.5" x 11") 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 30A Raynham silt loam, 0 to 3 percent slopes 2.0 82.6% 741A Amostown-Windsor silty substratum-Urban land complex, 0 to 3 percent slopes 0.0 0.4% 749B Windsor loamy sand, silty substratum, 3 to 8 percent slopes 0.4 17.0% Totals for Area of Interest 2.5 100.0% 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 Custom Soil Resource Report 10 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 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 11 Hampshire County, Massachusetts, Central Part 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 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 Custom Soil Resource Report 12 Landform: Depressions Scitico Percent of map unit: 5 percent Landform: Depressions 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 Frequency of ponding: None Available water storage in profile: High (about 9.3 inches) Custom Soil Resource Report 13 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 14 749B—Windsor loamy sand, silty substratum, 3 to 8 percent slopes Map Unit Setting National map unit symbol: 9b2l 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 Windsor and similar soils: 80 percent Minor components: 20 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Windsor 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: 3 to 8 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Somewhat excessively drained Runoff class: 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 Custom Soil Resource Report 15 Minor Components Enosburg Percent of map unit: 10 percent Landform: Terraces Pollux Percent of map unit: 5 percent Amostown Percent of map unit: 5 percent Custom Soil Resource Report 16 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 17 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 18 Sunwood Green – 95 Barrett Street Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Appendix B – Subsurface Investigation Results COLD SPRING ENVIRONMENTAL CONSULTANTS INC. • 21E Site Investigations • Percolation Tests • Subsurface Investigations • Septic Designs • Pollution Remediation • Regulatory Compliance • LSP on Staff • Recycling and Solid Waste • Forensic Septic InA5#Mff~~ 2015 • Second Opinions Mr. Mark Darnold The Berkshire Design Group, Inc. 4 Allen Place Northampton, MA 01060 RE: Test Pit & Soil Evaluation Results Proposed Development Off Barrett Street, Northampton, MA CSEC Reference File #115-4520-0409 Greetings Mark: Background: Cold Spring Environmental, Inc. was contracted to install test pits and perform soil evaluations (to evaluate drainage character of soil for the applicability of storm water drainage feasibility) at the above referenced property. This task was contracted by Mr. Perry to supplement your work and was conducted on April 8, 2015. 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. Five test pits (1-5) were installed as shown on the attached plan (located north to south). It was later decided that the five collected soil samples would just be held for possiblelater soil lab testing as needed. All excavations had poorly permeable substrata with perched seasonal high groundwater conditions. A Fairly consistent thick "A" or loam layer was noted (excepting #5) for 6-I 0" followed by a rather plastic fine sandy loam or silt loam layer with poor drainage qualities and Estimated Seasonal High Groundwater (ESHGW), perched at 20" to 36" below grade. This "Cl layer extended to 120 " in all excavations. The test pits were excavated using a Kabota tractor mounted backhoe provided by Shaul Perry and a Mini Bobcat excavator provided by Robbie Adair of Hadley. The soil evaluations followed procedures specified in 310 CMR 15.000 incl.uding percolation tests and soil evaluations. Overall, native soil types concurred with USDA mapping included Boxford Silt Loam (BoA & BoB) consisting of thick friable loam deposits underlain by mottled silt and clay. The Permeability of the sub soil is generally slow. The Mottling and silty, clayey nature posed by the soils in these locations is the very high ESHGW from 20"-36"below existing grade, may make drainage quite challenging. Please feel free to contact us with any questions you may have. Sincerely, Cold Spring Environmental Consultants, Inc. Alan~ Weiss, M.S., R.S., LSP Principal Hydrogeologist, MA Soil Evaluator 350 Old Enfield Road • Belchertown, MA. 01007 • Phone: 413.323.5957 Fax 413.323.4916 email: aeweiss@charter.net www.coldspringenvironmental.com Attachment1 Figure1:SiteLocus Figure2:SiteLayout(FromBDG) ColdSpringEnvironmentalConsultants,Inc. 350OldEnfieldRoad Belchertown,MA.01007 http://www.coldspringenvironmental.com Ph:413.323.5957 Fax:413.323.4916 email:aeweiss@charter.net FROMUSGS April2015FIGURE1—SITELOCUS SunwoodBuildersBarrettStreet Northampton,MA TP-2 TP-1 TP-3 TP-4 TP-4 Attachment2 TestPitPhotos TestPit1: BarrettStreet NorthamptonMA 04.08.2015 TestPit2 BarrettStreet NorthamptonMA 04.08.2015 TestPit3: BarrettStreet NorthamptonMA 04.08.2015 TestPit4: BarrettStreet NorthamptonMA 04.08.2015 TestPit2:CMaterial BarrettStreet NorthamptonMA 04.08.2015 TestPit5: BarrettStreet NorthamptonMA 04.08.2015 ATTACHMENTIII SoilEvaluationlogs tp1logonlyt5form12BDGsoilevalform2014.doc•rev.3/13Form11–SoilSuitabilityAssessmentforOn-SiteSewageDisposal•Page3of8 CommonwealthofMassachusettsCity/TownofNorthampton Form11-SoilSuitabilityAssessmentforOn-SiteSewageDisposal C.On-SiteReview (continued) DeepObservationHoleNumber:TP-1:offBarrettStreet Depth(in.)SoilHorizon/ Layer SoilMatrix:Color- Moist(Munsell) RedoximorphicFeatures (mottles)SoilTexture (USDA) CoarseFragments %byVolume Soil Structure Soil Consistence (Moist) Other DepthColorPercentGravel Cobbles& Stones 0-6"A10yr3.2FSLfriableroots 6-20"B7.5yr5.620"2.5Y4.1 15VFSLfinesandy 20-120"C17.5yr5.8"""FSL15%10%silty/firmwet/till Hetero- genous Massiveplatey ESHGW= 20" AdditionalNotes: tp2logonlyt5form12BDGsoilevalform2014.doc•rev.3/13Form11–SoilSuitabilityAssessmentforOn-SiteSewageDisposal•Page3of8 CommonwealthofMassachusettsCity/TownofNorthampton Form11-SoilSuitabilityAssessmentforOn-SiteSewageDisposal C.On-SiteReview (continued) DeepObservationHoleNumber:TP-2:offBarrettStreet Depth(in.)SoilHorizon/ Layer SoilMatrix:Color- Moist(Munsell) RedoximorphicFeatures (mottles)SoilTexture (USDA) CoarseFragments %byVolume Soil Structure Soil Consistence (Moist) Other DepthColorPercentGravel Cobbles& Stones 0-6"A10yr3.2FSLfriableroots 6-22"B7.5yr5.620"2.5Y4.1 20VFSLfinesandy 22-120"C17.5yr5.8"""FSL10%10%silty/firmwet/till Hetero- genous Massiveplatey ESHGW= 20" seepsat 22" AdditionalNotes: tp3logonlyt5form12BDGsoilevalform2014.doc•rev.3/13Form11–SoilSuitabilityAssessmentforOn-SiteSewageDisposal•Page3of8 CommonwealthofMassachusettsCity/TownofNorthampton Form11-SoilSuitabilityAssessmentforOn-SiteSewageDisposal C.On-SiteReview (continued) DeepObservationHoleNumber:TP-3:offBarrettStreet Depth(in.)SoilHorizon/ Layer SoilMatrix:Color- Moist(Munsell) RedoximorphicFeatures (mottles)SoilTexture (USDA) CoarseFragments %byVolume Soil Structure Soil Consistence (Moist) Other DepthColorPercentGravel Cobbles& Stones 0-8"A10yr3.2FSLfriableroots 8-24"B7.5yr5.624"5Yr3.320VFSLfinesandy 24-112"C17.5yr5.8"10yr5.2 "FSL10%10%silty/firmwet/till Hetero- genous Massiveplatey ESHGW= 24" seepsat 28" AdditionalNotes: tp4logonlyt5form12BDGsoilevalform2014.doc•rev.3/13Form11–SoilSuitabilityAssessmentforOn-SiteSewageDisposal•Page3of8 CommonwealthofMassachusettsCity/TownofNorthampton Form11-SoilSuitabilityAssessmentforOn-SiteSewageDisposal C.On-SiteReview (continued) DeepObservationHoleNumber:TP-4:offBarrettStreet Depth(in.)SoilHorizon/ Layer SoilMatrix:Color- Moist(Munsell) RedoximorphicFeatures (mottles)SoilTexture (USDA) CoarseFragments %byVolume Soil Structure Soil Consistence (Moist) Other DepthColorPercentGravel Cobbles& Stones 0-8"A10yr3.2FSLfriableroots 8-24"B7.5yr5.624"5Yr3.320LSfinesandy 24-122"C17.5yr5.8"10yr5.2 "FSL10%10%silty/firmwet/till Hetero- genous Massiveplatey ESHGW= 24" seepsat 26" AdditionalNotes: tp5logonlyt5form12BDGsoilevalform2014.doc•rev.3/13Form11–SoilSuitabilityAssessmentforOn-SiteSewageDisposal•Page3of8 CommonwealthofMassachusettsCity/TownofNorthampton Form11-SoilSuitabilityAssessmentforOn-SiteSewageDisposal C.On-SiteReview (continued) DeepObservationHoleNumber:TP-5:offBarrettStreet Depth(in.)SoilHorizon/ Layer SoilMatrix:Color- Moist(Munsell) RedoximorphicFeatures (mottles)SoilTexture (USDA) CoarseFragments %byVolume Soil Structure Soil Consistence (Moist) Other DepthColorPercentGravel Cobbles& Stones 0-22"Af10yr3.2Fill10%looseasphalt 8-22"A&Bmix 7.5yr5.6LSfinesandy 22-110"C17.5yr5.836"5yr5.2 20%siltloamsilty/platey wet/lake layers varved 2.5y4.1 &clayMassiveplatey ESHGW= 36" seepsat 36" AdditionalNotes: Sunwood Green – 95 Barrett Street Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Appendix C – Stormwater Hydrology Calculations E1 North Site E2 South Site E3 East Site CP1 Intermittent Stream CP2 Barrett Street CP3 Off-Site East CPT Barret Street Marsh Outlet Routing Diagram for 2014-122 Sunwood Green Pre-Development Prepared by Microsoft, Printed 5/28/2015 HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Subcat Reach Pond Link Type III 24-hr 2-Year Rainfall=3.00"2014-122 Sunwood Green Pre-Development Printed 5/28/2015Prepared by Microsoft Page 2HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 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=36,694 sf 0.00% Impervious Runoff Depth>0.78"Subcatchment E1: North Site Tc=5.0 min CN=73 Runoff=0.79 cfs 0.055 af Runoff Area=27,890 sf 2.92% Impervious Runoff Depth>0.98"Subcatchment E2: South Site Tc=5.0 min CN=77 Runoff=0.78 cfs 0.052 af Runoff Area=9,949 sf 0.00% Impervious Runoff Depth>0.69"Subcatchment E3: East Site Tc=5.0 min CN=71 Runoff=0.18 cfs 0.013 af Inflow=0.79 cfs 0.055 afReach CP1: Intermittent Stream Outflow=0.79 cfs 0.055 af Inflow=0.78 cfs 0.052 afReach CP2: Barrett Street Outflow=0.78 cfs 0.052 af Inflow=0.18 cfs 0.013 afReach CP3: Off-Site East Outflow=0.18 cfs 0.013 af Inflow=1.75 cfs 0.120 afReach CPT: Barret Street Marsh Outlet Outflow=1.75 cfs 0.120 af Type III 24-hr 2-Year Rainfall=3.00"2014-122 Sunwood Green Pre-Development Printed 5/28/2015Prepared by Microsoft Page 3HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Subcatchment E1: North Site Runoff=0.79 cfs @ 12.09 hrs, Volume=0.055 af, Depth>0.78" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.00" Area (sf)CNDescription 10696Gravel surface, HSG C 33,11774>75% Grass cover, Good, HSG C 3,47165Brush, Good, HSG C 36,69473Weighted Average 36,694100.00% Pervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Summary for Subcatchment E2: South Site Runoff=0.78 cfs @ 12.09 hrs, Volume=0.052 af, Depth>0.98" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.00" Area (sf)CNDescription 81498Paved parking, HSG C 2,87196Gravel surface, HSG C 24,20574>75% Grass cover, Good, HSG C 27,89077Weighted Average 27,07697.08% Pervious Area 8142.92% Impervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Summary for Subcatchment E3: East Site Runoff=0.18 cfs @ 12.09 hrs, Volume=0.013 af, Depth>0.69" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.00" Area (sf)CNDescription 6,28974>75% Grass cover, Good, HSG C 3,66065Brush, Good, HSG C 9,94971Weighted Average 9,949100.00% Pervious Area Type III 24-hr 2-Year Rainfall=3.00"2014-122 Sunwood Green Pre-Development Printed 5/28/2015Prepared by Microsoft Page 4HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Summary for Reach CP1: Intermittent Stream Inflow Area =0.842 ac,0.00% Impervious, Inflow Depth > 0.78" for 2-Year event Inflow=0.79 cfs @ 12.09 hrs, Volume=0.055 af Outflow=0.79 cfs @ 12.09 hrs, Volume=0.055 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Summary for Reach CP2: Barrett Street Inflow Area =0.640 ac,2.92% Impervious, Inflow Depth > 0.98" for 2-Year event Inflow=0.78 cfs @ 12.09 hrs, Volume=0.052 af Outflow=0.78 cfs @ 12.09 hrs, Volume=0.052 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Summary for Reach CP3: Off-Site East Inflow Area =0.228 ac,0.00% Impervious, Inflow Depth > 0.69" for 2-Year event Inflow=0.18 cfs @ 12.09 hrs, Volume=0.013 af Outflow=0.18 cfs @ 12.09 hrs, Volume=0.013 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Summary for Reach CPT: Barret Street Marsh Outlet Inflow Area =1.711 ac,1.09% Impervious, Inflow Depth > 0.84" for 2-Year event Inflow=1.75 cfs @ 12.09 hrs, Volume=0.120 af Outflow=1.75 cfs @ 12.09 hrs, Volume=0.120 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.50"2014-122 Sunwood Green Pre-Development Printed 5/28/2015Prepared by Microsoft Page 5HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 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=36,694 sf 0.00% Impervious Runoff Depth>1.75"Subcatchment E1: North Site Tc=5.0 min CN=73 Runoff=1.85 cfs 0.123 af Runoff Area=27,890 sf 2.92% Impervious Runoff Depth>2.05"Subcatchment E2: South Site Tc=5.0 min CN=77 Runoff=1.66 cfs 0.109 af Runoff Area=9,949 sf 0.00% Impervious Runoff Depth>1.61"Subcatchment E3: East Site Tc=5.0 min CN=71 Runoff=0.46 cfs 0.031 af Inflow=1.85 cfs 0.123 afReach CP1: Intermittent Stream Outflow=1.85 cfs 0.123 af Inflow=1.66 cfs 0.109 afReach CP2: Barrett Street Outflow=1.66 cfs 0.109 af Inflow=0.46 cfs 0.031 afReach CP3: Off-Site East Outflow=0.46 cfs 0.031 af Inflow=3.97 cfs 0.263 afReach CPT: Barret Street Marsh Outlet Outflow=3.97 cfs 0.263 af Type III 24-hr 10-Year Rainfall=4.50"2014-122 Sunwood Green Pre-Development Printed 5/28/2015Prepared by Microsoft Page 6HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Subcatchment E1: North Site Runoff=1.85 cfs @ 12.08 hrs, Volume=0.123 af, Depth>1.75" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.50" Area (sf)CNDescription 10696Gravel surface, HSG C 33,11774>75% Grass cover, Good, HSG C 3,47165Brush, Good, HSG C 36,69473Weighted Average 36,694100.00% Pervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Summary for Subcatchment E2: South Site Runoff=1.66 cfs @ 12.08 hrs, Volume=0.109 af, Depth>2.05" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.50" Area (sf)CNDescription 81498Paved parking, HSG C 2,87196Gravel surface, HSG C 24,20574>75% Grass cover, Good, HSG C 27,89077Weighted Average 27,07697.08% Pervious Area 8142.92% Impervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Summary for Subcatchment E3: East Site Runoff=0.46 cfs @ 12.08 hrs, Volume=0.031 af, Depth>1.61" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.50" Area (sf)CNDescription 6,28974>75% Grass cover, Good, HSG C 3,66065Brush, Good, HSG C 9,94971Weighted Average 9,949100.00% Pervious Area Type III 24-hr 10-Year Rainfall=4.50"2014-122 Sunwood Green Pre-Development Printed 5/28/2015Prepared by Microsoft Page 7HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Summary for Reach CP1: Intermittent Stream Inflow Area =0.842 ac,0.00% Impervious, Inflow Depth > 1.75" for 10-Year event Inflow=1.85 cfs @ 12.08 hrs, Volume=0.123 af Outflow=1.85 cfs @ 12.08 hrs, Volume=0.123 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Summary for Reach CP2: Barrett Street Inflow Area =0.640 ac,2.92% Impervious, Inflow Depth > 2.05" for 10-Year event Inflow=1.66 cfs @ 12.08 hrs, Volume=0.109 af Outflow=1.66 cfs @ 12.08 hrs, Volume=0.109 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Summary for Reach CP3: Off-Site East Inflow Area =0.228 ac,0.00% Impervious, Inflow Depth > 1.61" for 10-Year event Inflow=0.46 cfs @ 12.08 hrs, Volume=0.031 af Outflow=0.46 cfs @ 12.08 hrs, Volume=0.031 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Summary for Reach CPT: Barret Street Marsh Outlet Inflow Area =1.711 ac,1.09% Impervious, Inflow Depth > 1.84" for 10-Year event Inflow=3.97 cfs @ 12.08 hrs, Volume=0.263 af Outflow=3.97 cfs @ 12.08 hrs, Volume=0.263 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=6.40"2014-122 Sunwood Green Pre-Development Printed 5/28/2015Prepared by Microsoft Page 8HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 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=36,694 sf 0.00% Impervious Runoff Depth>3.19"Subcatchment E1: North Site Tc=5.0 min CN=73 Runoff=3.38 cfs 0.224 af Runoff Area=27,890 sf 2.92% Impervious Runoff Depth>3.58"Subcatchment E2: South Site Tc=5.0 min CN=77 Runoff=2.87 cfs 0.191 af Runoff Area=9,949 sf 0.00% Impervious Runoff Depth>3.00"Subcatchment E3: East Site Tc=5.0 min CN=71 Runoff=0.86 cfs 0.057 af Inflow=3.38 cfs 0.224 afReach CP1: Intermittent Stream Outflow=3.38 cfs 0.224 af Inflow=2.87 cfs 0.191 afReach CP2: Barrett Street Outflow=2.87 cfs 0.191 af Inflow=0.86 cfs 0.057 afReach CP3: Off-Site East Outflow=0.86 cfs 0.057 af Inflow=7.12 cfs 0.472 afReach CPT: Barret Street Marsh Outlet Outflow=7.12 cfs 0.472 af Type III 24-hr 100-Year Rainfall=6.40"2014-122 Sunwood Green Pre-Development Printed 5/28/2015Prepared by Microsoft Page 9HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Subcatchment E1: North Site Runoff=3.38 cfs @ 12.08 hrs, Volume=0.224 af, Depth>3.19" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=6.40" Area (sf)CNDescription 10696Gravel surface, HSG C 33,11774>75% Grass cover, Good, HSG C 3,47165Brush, Good, HSG C 36,69473Weighted Average 36,694100.00% Pervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Summary for Subcatchment E2: South Site Runoff=2.87 cfs @ 12.08 hrs, Volume=0.191 af, Depth>3.58" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=6.40" Area (sf)CNDescription 81498Paved parking, HSG C 2,87196Gravel surface, HSG C 24,20574>75% Grass cover, Good, HSG C 27,89077Weighted Average 27,07697.08% Pervious Area 8142.92% Impervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Summary for Subcatchment E3: East Site Runoff=0.86 cfs @ 12.08 hrs, Volume=0.057 af, Depth>3.00" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=6.40" Area (sf)CNDescription 6,28974>75% Grass cover, Good, HSG C 3,66065Brush, Good, HSG C 9,94971Weighted Average 9,949100.00% Pervious Area Type III 24-hr 100-Year Rainfall=6.40"2014-122 Sunwood Green Pre-Development Printed 5/28/2015Prepared by Microsoft Page 10HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Summary for Reach CP1: Intermittent Stream Inflow Area =0.842 ac,0.00% Impervious, Inflow Depth > 3.19" for 100-Year event Inflow=3.38 cfs @ 12.08 hrs, Volume=0.224 af Outflow=3.38 cfs @ 12.08 hrs, Volume=0.224 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Summary for Reach CP2: Barrett Street Inflow Area =0.640 ac,2.92% Impervious, Inflow Depth > 3.58" for 100-Year event Inflow=2.87 cfs @ 12.08 hrs, Volume=0.191 af Outflow=2.87 cfs @ 12.08 hrs, Volume=0.191 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Summary for Reach CP3: Off-Site East Inflow Area =0.228 ac,0.00% Impervious, Inflow Depth > 3.00" for 100-Year event Inflow=0.86 cfs @ 12.08 hrs, Volume=0.057 af Outflow=0.86 cfs @ 12.08 hrs, Volume=0.057 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Summary for Reach CPT: Barret Street Marsh Outlet Inflow Area =1.711 ac,1.09% Impervious, Inflow Depth > 3.31" for 100-Year event Inflow=7.12 cfs @ 12.08 hrs, Volume=0.472 af Outflow=7.12 cfs @ 12.08 hrs, Volume=0.472 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs P1 North Edge P2 South End P3 Central Site P4 East Edge CP1 Off-Site North CP2 Barrett Street CP3 Off-Site East CPT Barret Street Marsh Outlet D1 Detention Basin L1 Level Lip Spreader Routing Diagram for 2014-122 Sunwood Green Post-Development Prepared by Microsoft, Printed 5/28/2015 HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Subcat Reach Pond Link Type III 24-hr 2-Year Rainfall=3.00"2014-122 Sunwood Green Post-Development Printed 5/28/2015Prepared by Microsoft Page 2HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Time span=3.00-20.00 hrs, dt=0.05 hrs, 341 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=7,922 sf 1.16% Impervious Runoff Depth>0.69"Subcatchment P1: North Edge Tc=5.0 min CN=71 Runoff=0.15 cfs 0.010 af Runoff Area=18,949 sf 42.26% Impervious Runoff Depth>1.41"Subcatchment P2: South End Tc=5.0 min CN=84 Runoff=0.77 cfs 0.051 af Runoff Area=41,723 sf 67.15% Impervious Runoff Depth>1.86"Subcatchment P3: Central Site Tc=5.0 min CN=90 Runoff=2.22 cfs 0.149 af Runoff Area=6,085 sf 0.00% Impervious Runoff Depth>0.88"Subcatchment P4: East Edge Tc=5.0 min CN=75 Runoff=0.15 cfs 0.010 af Inflow=0.76 cfs 0.157 afReach CP1: Off-Site North Outflow=0.76 cfs 0.157 af Inflow=0.77 cfs 0.051 afReach CP2: Barrett Street Outflow=0.77 cfs 0.051 af Inflow=0.15 cfs 0.010 afReach CP3: Off-Site East Outflow=0.15 cfs 0.010 af Inflow=1.64 cfs 0.218 afReach CPT: Barret Street Marsh Outlet Outflow=1.64 cfs 0.218 af Peak Elev=98.36' Storage=1,737 cf Inflow=2.22 cfs 0.149 afPond D1: Detention Basin Outflow=0.69 cfs 0.147 af Peak Elev=96.04' Storage=31 cf Inflow=0.69 cfs 0.147 afPond L1: Level Lip Spreader Outflow=0.69 cfs 0.146 af Type III 24-hr 2-Year Rainfall=3.00"2014-122 Sunwood Green Post-Development Printed 5/28/2015Prepared by Microsoft Page 3HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Subcatchment P1: North Edge Runoff=0.15 cfs @ 12.09 hrs, Volume=0.010 af, Depth>0.69" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.00" Area (sf)CNDescription 9298Paved parking, HSG C 68991Fallow, bare soil, HSG C 3,82365Brush, Good, HSG C 3,31874>75% Grass cover, Good, HSG C 7,92271Weighted Average 7,83098.84% Pervious Area 921.16% Impervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Summary for Subcatchment P2: South End Runoff=0.77 cfs @ 12.08 hrs, Volume=0.051 af, Depth>1.41" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.00" Area (sf)CNDescription 8,00798Paved parking, HSG C 10,94274>75% Grass cover, Good, HSG C 18,94984Weighted Average 10,94257.74% Pervious Area 8,00742.26% Impervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Summary for Subcatchment P3: Central Site Runoff=2.22 cfs @ 12.07 hrs, Volume=0.149 af, Depth>1.86" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.00" Type III 24-hr 2-Year Rainfall=3.00"2014-122 Sunwood Green Post-Development Printed 5/28/2015Prepared by Microsoft Page 4HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Area (sf)CNDescription 28,01598Paved parking, HSG C 13,70874>75% Grass cover, Good, HSG C 41,72390Weighted Average 13,70832.85% Pervious Area 28,01567.15% Impervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Summary for Subcatchment P4: East Edge Runoff=0.15 cfs @ 12.09 hrs, Volume=0.010 af, Depth>0.88" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.00" Area (sf)CNDescription 93691Fallow, bare soil, HSG C 1,26365Brush, Good, HSG C 3,88674>75% Grass cover, Good, HSG C 6,08575Weighted Average 6,085100.00% Pervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Summary for Reach CP1: Off-Site North Inflow Area =1.140 ac,56.62% Impervious, Inflow Depth > 1.65" for 2-Year event Inflow=0.76 cfs @ 12.32 hrs, Volume=0.157 af Outflow=0.76 cfs @ 12.32 hrs, Volume=0.157 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Summary for Reach CP2: Barrett Street Inflow Area =0.435 ac,42.26% Impervious, Inflow Depth > 1.41" for 2-Year event Inflow=0.77 cfs @ 12.08 hrs, Volume=0.051 af Outflow=0.77 cfs @ 12.08 hrs, Volume=0.051 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.00"2014-122 Sunwood Green Post-Development Printed 5/28/2015Prepared by Microsoft Page 5HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Reach CP3: Off-Site East Inflow Area =0.140 ac,0.00% Impervious, Inflow Depth > 0.88" for 2-Year event Inflow=0.15 cfs @ 12.09 hrs, Volume=0.010 af Outflow=0.15 cfs @ 12.09 hrs, Volume=0.010 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Summary for Reach CPT: Barret Street Marsh Outlet Inflow Area =1.714 ac,48.36% Impervious, Inflow Depth > 1.53" for 2-Year event Inflow=1.64 cfs @ 12.09 hrs, Volume=0.218 af Outflow=1.64 cfs @ 12.09 hrs, Volume=0.218 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Summary for Pond D1: Detention Basin Inflow Area =0.958 ac,67.15% Impervious, Inflow Depth > 1.86" for 2-Year event Inflow=2.22 cfs @ 12.07 hrs, Volume=0.149 af Outflow=0.69 cfs @ 12.39 hrs, Volume=0.147 af, Atten= 69%, Lag= 19.2 min Primary=0.69 cfs @ 12.39 hrs, Volume=0.147 af Routing by Stor-Ind method, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 98.36' @ 12.39 hrs Surf.Area= 1,638 sf Storage= 1,737 cf Plug-Flow detention time= 29.2 min calculated for 0.147 af (99% of inflow) Center-of-Mass det. time= 24.4 min ( 800.3 - 775.9 ) VolumeInvertAvail.StorageStorage Description #196.50'1,468 cf Stone (Prismatic) Listed below (Recalc) 5,674 cf Overall - 2,002 cf Embedded = 3,671 cf x 40.0% Voids #297.00'1,471 cf 24.0" Round Pipe Storage Inside #1 L= 468.3' 2,002 cf Overall - 2.0" Wall Thickness = 1,471 cf #3100.00'3,395 cf Custom Stage Data (Prismatic) Listed below (Recalc) #497.00'28 cf 24.0" Round Pipe Storage L= 9.0' 6,363 cfTotal Available Storage ElevationSurf.AreaInc.StoreCum.Store (feet)(sq-ft)(cubic-feet)(cubic-feet) 96.501,62100 100.001,6215,6745,674 ElevationSurf.AreaInc.StoreCum.Store (feet)(sq-ft)(cubic-feet)(cubic-feet) 100.00100 101.002,8591,4301,430 101.505,0001,9653,395 Type III 24-hr 2-Year Rainfall=3.00"2014-122 Sunwood Green Post-Development Printed 5/28/2015Prepared by Microsoft Page 6HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC DeviceRouting InvertOutlet Devices #1Primary96.50'12.0" Round Culvert L= 10.0' CMP, square edge headwall, Ke= 0.500 Inlet / Outlet Invert= 96.50' / 96.40' S= 0.0100 '/' Cc= 0.900 n= 0.012, Flow Area= 0.79 sf #2Device 196.50'4.5" Vert. Orifice/Grate C= 0.600 #3Device 198.33'5.0" Vert. Orifice/Grate C= 0.600 #4Device 1100.00'6.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=0.69 cfs @ 12.39 hrs HW=98.36' (Free Discharge) 1=Culvert (Passes 0.69 cfs of 4.41 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.69 cfs @ 6.23 fps) 3=Orifice/Grate (Orifice Controls 0.00 cfs @ 0.59 fps) 4=Orifice/Grate ( Controls 0.00 cfs) Summary for Pond L1: Level Lip Spreader Inflow Area =0.958 ac,67.15% Impervious, Inflow Depth > 1.84" for 2-Year event Inflow=0.69 cfs @ 12.39 hrs, Volume=0.147 af Outflow=0.69 cfs @ 12.39 hrs, Volume=0.146 af, Atten= 0%, Lag= 0.0 min Primary=0.69 cfs @ 12.39 hrs, Volume=0.146 af Routing by Stor-Ind method, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs / 2 Peak Elev= 96.04' @ 12.39 hrs Surf.Area= 150 sf Storage= 31 cf Plug-Flow detention time= 2.6 min calculated for 0.146 af (99% of inflow) Center-of-Mass det. time= 1.3 min ( 801.6 - 800.3 ) VolumeInvertAvail.StorageStorage Description #195.00'251 cf Custom Stage Data (Prismatic) Listed below (Recalc) 628 cf Overall x 40.0% Voids ElevationSurf.AreaInc.StoreCum.Store (feet)(sq-ft)(cubic-feet)(cubic-feet) 95.003200 96.001127272 97.001,000556628 DeviceRouting InvertOutlet Devices #1Primary96.00'30.0' long x 2.0' 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 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 Primary OutFlow Max=0.68 cfs @ 12.39 hrs HW=96.04' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 0.68 cfs @ 0.53 fps) Type III 24-hr 10-Year Rainfall=4.50"2014-122 Sunwood Green Post-Development Printed 5/28/2015Prepared by Microsoft Page 7HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Time span=3.00-20.00 hrs, dt=0.05 hrs, 341 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=7,922 sf 1.16% Impervious Runoff Depth>1.61"Subcatchment P1: North Edge Tc=5.0 min CN=71 Runoff=0.37 cfs 0.024 af Runoff Area=18,949 sf 42.26% Impervious Runoff Depth>2.64"Subcatchment P2: South End Tc=5.0 min CN=84 Runoff=1.43 cfs 0.096 af Runoff Area=41,723 sf 67.15% Impervious Runoff Depth>3.21"Subcatchment P3: Central Site Tc=5.0 min CN=90 Runoff=3.72 cfs 0.256 af Runoff Area=6,085 sf 0.00% Impervious Runoff Depth>1.90"Subcatchment P4: East Edge Tc=5.0 min CN=75 Runoff=0.33 cfs 0.022 af Inflow=1.81 cfs 0.278 afReach CP1: Off-Site North Outflow=1.81 cfs 0.278 af Inflow=1.43 cfs 0.096 afReach CP2: Barrett Street Outflow=1.43 cfs 0.096 af Inflow=0.33 cfs 0.022 afReach CP3: Off-Site East Outflow=0.33 cfs 0.022 af Inflow=3.27 cfs 0.395 afReach CPT: Barret Street Marsh Outlet Outflow=3.27 cfs 0.395 af Peak Elev=99.67' Storage=2,753 cf Inflow=3.72 cfs 0.256 afPond D1: Detention Basin Outflow=1.62 cfs 0.254 af Peak Elev=96.08' Storage=33 cf Inflow=1.62 cfs 0.254 afPond L1: Level Lip Spreader Outflow=1.61 cfs 0.253 af Type III 24-hr 10-Year Rainfall=4.50"2014-122 Sunwood Green Post-Development Printed 5/28/2015Prepared by Microsoft Page 8HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Subcatchment P1: North Edge Runoff=0.37 cfs @ 12.08 hrs, Volume=0.024 af, Depth>1.61" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.50" Area (sf)CNDescription 9298Paved parking, HSG C 68991Fallow, bare soil, HSG C 3,82365Brush, Good, HSG C 3,31874>75% Grass cover, Good, HSG C 7,92271Weighted Average 7,83098.84% Pervious Area 921.16% Impervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Summary for Subcatchment P2: South End Runoff=1.43 cfs @ 12.08 hrs, Volume=0.096 af, Depth>2.64" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.50" Area (sf)CNDescription 8,00798Paved parking, HSG C 10,94274>75% Grass cover, Good, HSG C 18,94984Weighted Average 10,94257.74% Pervious Area 8,00742.26% Impervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Summary for Subcatchment P3: Central Site Runoff=3.72 cfs @ 12.07 hrs, Volume=0.256 af, Depth>3.21" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.50" Type III 24-hr 10-Year Rainfall=4.50"2014-122 Sunwood Green Post-Development Printed 5/28/2015Prepared by Microsoft Page 9HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Area (sf)CNDescription 28,01598Paved parking, HSG C 13,70874>75% Grass cover, Good, HSG C 41,72390Weighted Average 13,70832.85% Pervious Area 28,01567.15% Impervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Summary for Subcatchment P4: East Edge Runoff=0.33 cfs @ 12.08 hrs, Volume=0.022 af, Depth>1.90" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.50" Area (sf)CNDescription 93691Fallow, bare soil, HSG C 1,26365Brush, Good, HSG C 3,88674>75% Grass cover, Good, HSG C 6,08575Weighted Average 6,085100.00% Pervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Summary for Reach CP1: Off-Site North Inflow Area =1.140 ac,56.62% Impervious, Inflow Depth > 2.92" for 10-Year event Inflow=1.81 cfs @ 12.22 hrs, Volume=0.278 af Outflow=1.81 cfs @ 12.22 hrs, Volume=0.278 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Summary for Reach CP2: Barrett Street Inflow Area =0.435 ac,42.26% Impervious, Inflow Depth > 2.64" for 10-Year event Inflow=1.43 cfs @ 12.08 hrs, Volume=0.096 af Outflow=1.43 cfs @ 12.08 hrs, Volume=0.096 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.50"2014-122 Sunwood Green Post-Development Printed 5/28/2015Prepared by Microsoft Page 10HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Reach CP3: Off-Site East Inflow Area =0.140 ac,0.00% Impervious, Inflow Depth > 1.90" for 10-Year event Inflow=0.33 cfs @ 12.08 hrs, Volume=0.022 af Outflow=0.33 cfs @ 12.08 hrs, Volume=0.022 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Summary for Reach CPT: Barret Street Marsh Outlet Inflow Area =1.714 ac,48.36% Impervious, Inflow Depth > 2.77" for 10-Year event Inflow=3.27 cfs @ 12.11 hrs, Volume=0.395 af Outflow=3.27 cfs @ 12.11 hrs, Volume=0.395 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Summary for Pond D1: Detention Basin Inflow Area =0.958 ac,67.15% Impervious, Inflow Depth > 3.21" for 10-Year event Inflow=3.72 cfs @ 12.07 hrs, Volume=0.256 af Outflow=1.62 cfs @ 12.26 hrs, Volume=0.254 af, Atten= 57%, Lag= 11.4 min Primary=1.62 cfs @ 12.26 hrs, Volume=0.254 af Routing by Stor-Ind method, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 99.67' @ 12.26 hrs Surf.Area= 1,621 sf Storage= 2,753 cf Plug-Flow detention time= 27.7 min calculated for 0.254 af (99% of inflow) Center-of-Mass det. time= 24.0 min ( 786.9 - 762.9 ) VolumeInvertAvail.StorageStorage Description #196.50'1,468 cf Stone (Prismatic) Listed below (Recalc) 5,674 cf Overall - 2,002 cf Embedded = 3,671 cf x 40.0% Voids #297.00'1,471 cf 24.0" Round Pipe Storage Inside #1 L= 468.3' 2,002 cf Overall - 2.0" Wall Thickness = 1,471 cf #3100.00'3,395 cf Custom Stage Data (Prismatic) Listed below (Recalc) #497.00'28 cf 24.0" Round Pipe Storage L= 9.0' 6,363 cfTotal Available Storage ElevationSurf.AreaInc.StoreCum.Store (feet)(sq-ft)(cubic-feet)(cubic-feet) 96.501,62100 100.001,6215,6745,674 ElevationSurf.AreaInc.StoreCum.Store (feet)(sq-ft)(cubic-feet)(cubic-feet) 100.00100 101.002,8591,4301,430 101.505,0001,9653,395 Type III 24-hr 10-Year Rainfall=4.50"2014-122 Sunwood Green Post-Development Printed 5/28/2015Prepared by Microsoft Page 11HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC DeviceRouting InvertOutlet Devices #1Primary96.50'12.0" Round Culvert L= 10.0' CMP, square edge headwall, Ke= 0.500 Inlet / Outlet Invert= 96.50' / 96.40' S= 0.0100 '/' Cc= 0.900 n= 0.012, Flow Area= 0.79 sf #2Device 196.50'4.5" Vert. Orifice/Grate C= 0.600 #3Device 198.33'5.0" Vert. Orifice/Grate C= 0.600 #4Device 1100.00'6.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=1.61 cfs @ 12.26 hrs HW=99.66' (Free Discharge) 1=Culvert (Passes 1.61 cfs of 6.17 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.92 cfs @ 8.30 fps) 3=Orifice/Grate (Orifice Controls 0.70 cfs @ 5.10 fps) 4=Orifice/Grate ( Controls 0.00 cfs) Summary for Pond L1: Level Lip Spreader Inflow Area =0.958 ac,67.15% Impervious, Inflow Depth > 3.18" for 10-Year event Inflow=1.62 cfs @ 12.26 hrs, Volume=0.254 af Outflow=1.61 cfs @ 12.26 hrs, Volume=0.253 af, Atten= 0%, Lag= 0.0 min Primary=1.61 cfs @ 12.26 hrs, Volume=0.253 af Routing by Stor-Ind method, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs / 2 Peak Elev= 96.08' @ 12.26 hrs Surf.Area= 180 sf Storage= 33 cf Plug-Flow detention time= 1.8 min calculated for 0.253 af (100% of inflow) Center-of-Mass det. time= 1.0 min ( 787.9 - 786.9 ) VolumeInvertAvail.StorageStorage Description #195.00'251 cf Custom Stage Data (Prismatic) Listed below (Recalc) 628 cf Overall x 40.0% Voids ElevationSurf.AreaInc.StoreCum.Store (feet)(sq-ft)(cubic-feet)(cubic-feet) 95.003200 96.001127272 97.001,000556628 DeviceRouting InvertOutlet Devices #1Primary96.00'30.0' long x 2.0' 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 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 Primary OutFlow Max=1.60 cfs @ 12.26 hrs HW=96.08' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 1.60 cfs @ 0.70 fps) Type III 24-hr 100-Year Rainfall=6.40"2014-122 Sunwood Green Post-Development Printed 5/28/2015Prepared by Microsoft Page 12HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Time span=3.00-20.00 hrs, dt=0.05 hrs, 341 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=7,922 sf 1.16% Impervious Runoff Depth>3.00"Subcatchment P1: North Edge Tc=5.0 min CN=71 Runoff=0.69 cfs 0.045 af Runoff Area=18,949 sf 42.26% Impervious Runoff Depth>4.31"Subcatchment P2: South End Tc=5.0 min CN=84 Runoff=2.30 cfs 0.156 af Runoff Area=41,723 sf 67.15% Impervious Runoff Depth>4.96"Subcatchment P3: Central Site Tc=5.0 min CN=90 Runoff=5.61 cfs 0.396 af Runoff Area=6,085 sf 0.00% Impervious Runoff Depth>3.38"Subcatchment P4: East Edge Tc=5.0 min CN=75 Runoff=0.59 cfs 0.039 af Inflow=3.38 cfs 0.438 afReach CP1: Off-Site North Outflow=3.38 cfs 0.438 af Inflow=2.30 cfs 0.156 afReach CP2: Barrett Street Outflow=2.30 cfs 0.156 af Inflow=0.59 cfs 0.039 afReach CP3: Off-Site East Outflow=0.59 cfs 0.039 af Inflow=6.17 cfs 0.634 afReach CPT: Barret Street Marsh Outlet Outflow=6.17 cfs 0.634 af Peak Elev=100.80' Storage=3,877 cf Inflow=5.61 cfs 0.396 afPond D1: Detention Basin Outflow=2.91 cfs 0.393 af Peak Elev=96.11' Storage=36 cf Inflow=2.91 cfs 0.393 afPond L1: Level Lip Spreader Outflow=2.91 cfs 0.393 af Type III 24-hr 100-Year Rainfall=6.40"2014-122 Sunwood Green Post-Development Printed 5/28/2015Prepared by Microsoft Page 13HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Subcatchment P1: North Edge Runoff=0.69 cfs @ 12.08 hrs, Volume=0.045 af, Depth>3.00" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=6.40" Area (sf)CNDescription 9298Paved parking, HSG C 68991Fallow, bare soil, HSG C 3,82365Brush, Good, HSG C 3,31874>75% Grass cover, Good, HSG C 7,92271Weighted Average 7,83098.84% Pervious Area 921.16% Impervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Summary for Subcatchment P2: South End Runoff=2.30 cfs @ 12.07 hrs, Volume=0.156 af, Depth>4.31" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=6.40" Area (sf)CNDescription 8,00798Paved parking, HSG C 10,94274>75% Grass cover, Good, HSG C 18,94984Weighted Average 10,94257.74% Pervious Area 8,00742.26% Impervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Summary for Subcatchment P3: Central Site Runoff=5.61 cfs @ 12.07 hrs, Volume=0.396 af, Depth>4.96" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=6.40" Type III 24-hr 100-Year Rainfall=6.40"2014-122 Sunwood Green Post-Development Printed 5/28/2015Prepared by Microsoft Page 14HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Area (sf)CNDescription 28,01598Paved parking, HSG C 13,70874>75% Grass cover, Good, HSG C 41,72390Weighted Average 13,70832.85% Pervious Area 28,01567.15% Impervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Summary for Subcatchment P4: East Edge Runoff=0.59 cfs @ 12.08 hrs, Volume=0.039 af, Depth>3.38" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=6.40" Area (sf)CNDescription 93691Fallow, bare soil, HSG C 1,26365Brush, Good, HSG C 3,88674>75% Grass cover, Good, HSG C 6,08575Weighted Average 6,085100.00% Pervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Summary for Reach CP1: Off-Site North Inflow Area =1.140 ac,56.62% Impervious, Inflow Depth > 4.61" for 100-Year event Inflow=3.38 cfs @ 12.10 hrs, Volume=0.438 af Outflow=3.38 cfs @ 12.10 hrs, Volume=0.438 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Summary for Reach CP2: Barrett Street Inflow Area =0.435 ac,42.26% Impervious, Inflow Depth > 4.31" for 100-Year event Inflow=2.30 cfs @ 12.07 hrs, Volume=0.156 af Outflow=2.30 cfs @ 12.07 hrs, Volume=0.156 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=6.40"2014-122 Sunwood Green Post-Development Printed 5/28/2015Prepared by Microsoft Page 15HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC Summary for Reach CP3: Off-Site East Inflow Area =0.140 ac,0.00% Impervious, Inflow Depth > 3.38" for 100-Year event Inflow=0.59 cfs @ 12.08 hrs, Volume=0.039 af Outflow=0.59 cfs @ 12.08 hrs, Volume=0.039 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Summary for Reach CPT: Barret Street Marsh Outlet Inflow Area =1.714 ac,48.36% Impervious, Inflow Depth > 4.44" for 100-Year event Inflow=6.17 cfs @ 12.10 hrs, Volume=0.634 af Outflow=6.17 cfs @ 12.10 hrs, Volume=0.634 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Summary for Pond D1: Detention Basin Inflow Area =0.958 ac,67.15% Impervious, Inflow Depth > 4.96" for 100-Year event Inflow=5.61 cfs @ 12.07 hrs, Volume=0.396 af Outflow=2.91 cfs @ 12.21 hrs, Volume=0.393 af, Atten= 48%, Lag= 8.3 min Primary=2.91 cfs @ 12.21 hrs, Volume=0.393 af Routing by Stor-Ind method, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 100.80' @ 12.21 hrs Surf.Area= 3,900 sf Storage= 3,877 cf Plug-Flow detention time= 25.5 min calculated for 0.393 af (99% of inflow) Center-of-Mass det. time= 22.5 min ( 775.0 - 752.4 ) VolumeInvertAvail.StorageStorage Description #196.50'1,468 cf Stone (Prismatic) Listed below (Recalc) 5,674 cf Overall - 2,002 cf Embedded = 3,671 cf x 40.0% Voids #297.00'1,471 cf 24.0" Round Pipe Storage Inside #1 L= 468.3' 2,002 cf Overall - 2.0" Wall Thickness = 1,471 cf #3100.00'3,395 cf Custom Stage Data (Prismatic) Listed below (Recalc) #497.00'28 cf 24.0" Round Pipe Storage L= 9.0' 6,363 cfTotal Available Storage ElevationSurf.AreaInc.StoreCum.Store (feet)(sq-ft)(cubic-feet)(cubic-feet) 96.501,62100 100.001,6215,6745,674 ElevationSurf.AreaInc.StoreCum.Store (feet)(sq-ft)(cubic-feet)(cubic-feet) 100.00100 101.002,8591,4301,430 101.505,0001,9653,395 Type III 24-hr 100-Year Rainfall=6.40"2014-122 Sunwood Green Post-Development Printed 5/28/2015Prepared by Microsoft Page 16HydroCAD® 10.00-12 s/n 00752 © 2014 HydroCAD Software Solutions LLC DeviceRouting InvertOutlet Devices #1Primary96.50'12.0" Round Culvert L= 10.0' CMP, square edge headwall, Ke= 0.500 Inlet / Outlet Invert= 96.50' / 96.40' S= 0.0100 '/' Cc= 0.900 n= 0.012, Flow Area= 0.79 sf #2Device 196.50'4.5" Vert. Orifice/Grate C= 0.600 #3Device 198.33'5.0" Vert. Orifice/Grate C= 0.600 #4Device 1100.00'6.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=2.90 cfs @ 12.21 hrs HW=100.79' (Free Discharge) 1=Culvert (Passes 2.90 cfs of 7.36 cfs potential flow) 2=Orifice/Grate (Orifice Controls 1.08 cfs @ 9.76 fps) 3=Orifice/Grate (Orifice Controls 0.99 cfs @ 7.23 fps) 4=Orifice/Grate (Orifice Controls 0.84 cfs @ 4.29 fps) Summary for Pond L1: Level Lip Spreader Inflow Area =0.958 ac,67.15% Impervious, Inflow Depth > 4.93" for 100-Year event Inflow=2.91 cfs @ 12.21 hrs, Volume=0.393 af Outflow=2.91 cfs @ 12.21 hrs, Volume=0.393 af, Atten= 0%, Lag= 0.0 min Primary=2.91 cfs @ 12.21 hrs, Volume=0.393 af Routing by Stor-Ind method, Time Span= 3.00-20.00 hrs, dt= 0.05 hrs / 2 Peak Elev= 96.11' @ 12.21 hrs Surf.Area= 212 sf Storage= 36 cf Plug-Flow detention time= 1.5 min calculated for 0.392 af (100% of inflow) Center-of-Mass det. time= 0.9 min ( 775.8 - 775.0 ) VolumeInvertAvail.StorageStorage Description #195.00'251 cf Custom Stage Data (Prismatic) Listed below (Recalc) 628 cf Overall x 40.0% Voids ElevationSurf.AreaInc.StoreCum.Store (feet)(sq-ft)(cubic-feet)(cubic-feet) 95.003200 96.001127272 97.001,000556628 DeviceRouting InvertOutlet Devices #1Primary96.00'30.0' long x 2.0' 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 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 Primary OutFlow Max=2.89 cfs @ 12.21 hrs HW=96.11' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 2.89 cfs @ 0.85 fps) Sunwood Green – 95 Barrett Street Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Appendix D – Water Quality Calculations IN S T R U C T I O N S : Non-automated: Mar. 4, 2008 1. S h e e t i s n o n a u t o m a t e d . P r i n t s h e e t a n d c o m p l e t e u s i n g h a n d c a l c u l a t i o n s . C o l u m n A a n d B : S e e M a s s D E P S t r u c t u r a l B M P T a b l e 2. T h e c a l c u l a t i o n s m u s t b e c o m p l e t e d u s i n g t h e C o l u m n H e a d i n g s s p e c i f i e d i n C h a r t a n d N o t t h e E x c e l C o l u m n H e a d i n g s 3. T o c o m p l e t e C h a r t C o l u m n D , m u l t i p l e C o l u m n B v a l u e w i t h i n R o w x C o l u m n C v a l u e w i t h i n R o w 4. T o c o m p l e t e C h a r t C o l u m n E v a l u e , s u b t r a c t C o l u m n D v a l u e w i t h i n R o w f r o m C o l u m n C w i t h i n R o w 5. T o t a l T S S R e m o v a l = S u m A l l V a l u e s i n C o l u m n D Lo c a t i o n : A B C D E TS S R e m o v a l S t a r t i n g T S S A m o u n t R e m a i n i n g BM P 1 Ra t e 1 Lo a d * R e m o v e d ( B * C ) L o a d ( C - D ) 1. 0 0 To t a l T S S R e m o v a l = Separate Form Needs to be Completed for Each Outlet or BMP Train Pr o j e c t : Pr e p a r e d B y : *E q u a l s r e m a i n i n g l o a d f r o m p r e v i o u s B M P ( E ) Da t e : wh i c h e n t e r s t h e B M P TSS Removal Calculation Worksheet No n - a u t o m a t e d T S S C a l c u l a t i o n S h e e t m u s t b e u s e d i f P r o p r i e t a r y B M P P r o p o s e d 1. F r o m M a s s D E P S t o r m w a t e r H a n d b o o k V o l . 1 Ma s s . D e p t . o f E n v i r o n m e n t a l P r o t e c t i o n 4 Allen Place, Northampton, MA 01060 (413) 582-7000 bdg@berkshiredesign.com Sunwood Green Stormceptor Design Summary The Sunwood Green project proposes the installation of a stormwater treatment chamber (Stormceptor or equivalent) for removal of TSS and improvement of water quality immediately upstream of the proposed underground detention basin. The following is a summary of the Stormceptor design, completed by Berkshire Design Group using the PCSWMM software. Project Information Analysis Date: 5/27/2015 Project Name: Sunwood Green Project Number: 2015-009 Location: 95 Barrett Street, Northampton, MA Designer Information Company: The Berkshire Design Group, Inc. Contact: Chris Chamberland Drainage Area Total Area: 0.85 acres Imperviousness: 64% Rainfall Name: Knightville Dam State: MA ID: 3985 Years of Records: 1984 to 1997 Latitude: 42° 10’ 12”N Longitude: 72° 31’12”W Water Quality Objective TSS Removal: 80% Particle Size Distribution Particle (mmmmm) % Specific Grav. 20 20 1.3 60 20 1.8 150 20 2.2 400 20 2.65 2000 20 2.65 Stormceptor Sizing Summary Model TSS Removal (%) STC 450i 81 STC 900 88 STC 1200 88 STC 1800 88 STC 2400 91 STC 3600 92 SCT 4800 94 Sunwood Green – 95 Barrett Street Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Appendix E – Stormwater Management System – Operation & Maintenance Plan Sunwood Green – 95 Barrett Street May 28, 2015 Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 1 Stormwater Management System Operation & Maintenance Plan 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. Sunwood Green – 95 Barrett Street May 28, 2015 Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 2 Post-Construction Stormwater Management System Owner: Sunwood Green Condo Association (or similar legal entity TBD) 95 Barrett Street Northampton, MA 01060 Party Responsible for Operation & Maintenance: Sunwood Green Condo Association (or similar legal entity TBD) 95 Barrett Street Northampton, MA 01060 Inspection & Maintenance Schedule: 1) Stone Diaphragm Drain The diaphragm drain shall be inspected at least four times per year and cleaned annually, or more frequently if required. Failure of the system to drain (ponding after the end of the storm) shall result in inspection and cleaning. Drain shall be cleaned by removing and replacing pea stone top-dressing and removing any sediment collected on the exposed filter fabric. Stone may be washed and re-used. Oil and 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 and adjacent to drain, which shall be repaired immediately. It is recommended that sediment removal be performed after the completion of the spring snow melt. 2) Drain Structures Structures shall be inspected at least four times per year and cleaned annually, or more frequently if required. Oil and sediments shall 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. 3) Stormwater Treatment Chambers The Stormwater Treatment Chamber (Stormceptor STC450i, or equal) shall be inspected and maintained according the manufacturer’s specifications. Rinker, the manufacturer of Stormceptor recommends that maintenance be completed on the structures at least once per year, but advises that the units be checked once every three months during the first year to determine the rate of sediment and oil accumulation and to establish an appropriate maintenance schedule. The rate at which the system collects pollutants will depend on site activities. Maintenance or cleaning shall be performed when the stored volume reaches 15% (6 inch sediment depth) of the Stormceptor capacity, when oil (hydrocarbon) has accumulated to 1 inch or greater depth, or immediately in the event of a fuel or oil spill according the manufacturer’s specifications. All material removed from the Stormceptor shall be disposed in Sunwood Green – 95 Barrett Street May 28, 2015 Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Page 3 accordance with applicable local, state, and federal guidelines and regulations. For more detail on maintenance of the StormCeptor units, see the Stormceptor Owner Manual. 4) Subsurface Detention Basin & Outlet Control Structure The subsurface detention basin requires regular removal of accumulated sediment to maintain volume capacity. Pretreatment BMPs (diaphragm drain, treatment chamber) shall be inspected and cleaned as specified above. Proper maintenance of roof gutters and pretreatment systems will help to protect the integrity of the subsurface detention basin. The outlet control structure shall be inspected after large storms to ensure no debris is prohibiting flow through the outlet orifices in the riser pipe. All materials removed from the detention basin and outlet control structure shall be removed and disposed of in accordance with local, state and federal guidelines and regulations. The Subsurface Detention Structure shall be inspected twice a year, and if any sediment is observed within the structure, the structure shall be cleaned. The structure can be cleaned by jetting water from the manifold with multiple access ports toward the opposite manifold, and then jetting from one end of the manifold to the other end, and then any accumulated sediment may be vacuumed out. 5) Level Spreader The level spreader shall be inspected once per month and after any rainfall greater than one inch during the first year of operation, and four times per year or after any rainfall greater than one inch thereafter. Inspections shall identify any damage to the level spreader, low spots and signs of erosion at or near the level spreader, which shall be repaired immediately. Sunwood Green – 95 Barrett Street Northampton, Massachusetts Stormwater Management Report The Berkshire Design Group, Inc. Appendix F – MassDEP 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 2 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report B. Stormwater Checklist and Certification The following checklist is intended to serve as a guide for applicants as to the elements that ordinarily need to be addressed in a complete Stormwater Report. The checklist is also intended to provide conservation commissions and other reviewing authorities with a summary of the components necessary for a comprehensive Stormwater Report that addresses the ten Stormwater Standards. Note: Because stormwater requirements vary from project to project, it is possible that a complete Stormwater Report may not include information on some of the subjects specified in the Checklist. If it is determined that a specific item does not apply to the project under review, please note that the item is not applicable (N.A.) and provide the reasons for that determination. A complete checklist must include the Certification set forth below signed by the Registered Professional Engineer who prepared the Stormwater Report. Registered Professional Engineer’s Certification I have reviewed the Stormwater Report, including the soil evaluation, computations, Long-term Pollution Prevention Plan, the Construction Period Erosion and Sedimentation Control Plan (if included), the Long- term Post-Construction Operation and Maintenance Plan, the Illicit Discharge Compliance Statement (if included) and the plans showing the stormwater management system, and have determined that they have been prepared in accordance with the requirements of the Stormwater Management Standards as further elaborated by the Massachusetts Stormwater Handbook. I have also determined that the information presented in the Stormwater Checklist is accurate and that the information presented in the Stormwater Report accurately reflects conditions at the site as of the date of this permit application. Registered Professional Engineer Block and Signature Signature and Date Checklist Project Type: Is the application for new development, redevelopment, or a mix of new and redevelopment? New development Redevelopment Mix of New Development and Redevelopment 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 measures 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.