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Drainage Report-062420 Stormwater Management Plan Proposed Development of Skinner View Townhouses 30 Williams Street Northampton, Massachusetts June 09, 2020 Prepared for: P-tush 2, LLC 52 Prospect Ave Northampton, MA 01060 Skinner View Townhouses June 10, 2020 Northampton, Massachusetts 2 Table of Contents I. Introduction _______________________________________________________________ 3 II. Site Soils _________________________________________________________________ 4 III. Developed (Existing) Conditions-Pre __________________________________________ 5 IV. Development (Proposed) Conditions-Post ______________________________________ 6 V. Calculations & Design _____________________________________________________ 10 VI. Summary ______________________________________________________________ 12 Guiding Specifications for Bioretention ____________________________________________ 13 Operation & Maintenance Plan ___________________________________________________ 16 Existing Drainage Map_________________________________________________________ 19 Proposed Drainage Map _______________________________________________________ 20 USGS Soils Data _____________________________________________________________ 21 Data Source Information ________________________________________________________ 24 HydroCAD Calculation Pre-development ________________________________________________________25 Post-Development ______________________________________________________40 Skinner View Townhouses June 10, 2020 Northampton, Massachusetts 3 I. Introduction The site of the proposed Skinner View Townhouse development is located at 30 Williams Street in Northampton, MA. The property is comprised of two (2) parcels totaling 1.23 acres. The proposed development will be located on parce l 2, which is comprised of of 38,132 square feet (0.87 acres) of undeveloped land. Parcel 1 consist s of an existing single-family structure, a studio space, and a barn , with associated driveway and parking spaces. Parcel 1 will remain developed as is currently, with some minor site work added. Fig. 1 USGS Map The purpose of this analysis is to determine the 2, 10, and 100 -year peak flow rates according to current site conditions, and subsequently to design a stormwater management system that will (equalize) mitigate the impact of any increased peak runoff from the proposed site. The Skinner View Townhouses June 10, 2020 Northampton, Massachusetts 4 stormwater management system is designed in accordance with both the DEP Best Management Practices, which address stormwater peak flow rates, quantity, quality, and the Low Impact Development (LID). LID technology is an alternative comprehensive approach to stormwater management. It can be used to address a wide range of Wet Weather Flow (WWF) issues, including National Pollutant Discharge Elimi nation System (NPDES) Stormwater Phase II permits, Total Maximum Daily Load (TMDL) permits, Nonpoint Source Program goals, and other Water Quality Standards. II. Site Soils The soils data are taken from W eb Soil Survey, USDA Soil Survey of Hampshire County. Soil maps in the area indicate 2 types of soils: a) Hadley-Winooski-Urban land complex b) Limerick silt loam Most of the soils are comprised of silt loam to loamy fine sand, which has a low runoff class, and are considered a well-drained class. Soils are classified as type B in the computer model as per https://websoilsurvey.sc.egov.usda.gov/App/WebSoilSurv ey.aspx. Skinner View Townhouses June 10, 2020 Northampton, Massachusetts 5 Fig. 2 - USDA Soil Survey of Hampshire County III. Pre-Developed (Existing) Conditions The land, which is proposed for development, is mostly flat close to the Williams Street frontage, with a gentle slope toward the east side. A gradual slope to the east with about 9 feet of elevation is visible along the line that separates between the two soil types. The portion of the property to be developed is approximately 0.88 acre of the total 1.24 acres property, which includes 2 parcels. The watershed in this analysis, comprised of approximately 1 .5 acres, (of the property that) is divided into four (4) distinct drainage basins and shown on the attached map entitled “Existing Drainage Areas.” Expected peak rates of stormwater runoff are calculated for each drainage sub -basin using the Skinner View Townhouses June 10, 2020 Northampton, Massachusetts 6 HydroCAD computer model , see pages 18-23. They are then compared to the projected post-development conditions. Area 1S is 3,742 square feet of land, represents the sub-basin runoff that currently drains westerly toward Williams Street and into the City drainage system. Area 2S is 5,930 square feet of land, represents the sub-basin runoff that currently drains southerly toward the neighbor’s land. Area 3S is 32,438 square feet of land, represents the sub-basin runoff of that main area, which is proposed for development, that currently drains easterly toward the dike. The runoff from this area is being collected by 2 sets of catch basins that are located on the parcel and run into a 24 RCP pipe. Area 4S is 23,011 square feet of land, represents the sub-basin runoff that currently drains southerly through the woods and into the city system. Peak rates of flow for these areas were calculated to develop the baseline “allowable” flows that may not be exceede d after development. Flow paths across the sub-areas range from 85 feet to 235 feet. Based on the various ground slopes and ground cover, times of concentration are calculated for each sub-area in the range of 1 to 5 minutes. IV. Post-Development (Proposed) Conditions Proposed development of 6 new housing units and associated driveways, parking, and lawn areas will mimic the existing stormwater patterns. Runoff surface from the main area will be directed by overland flow to an open bio-retention basin with outlet control structure and an emergency overflow. Existing drainage patterns will remain unaffected by using stormwater management control, and LID technology. Flow is maintained in each identified pre-development sub-basin 1 to 4. Stormwater runoff from the proposed paved area will be directed into proposed bio -retention cells/basins. Stormwater from all rooftops will be directed through a gutter system into a perimeter roof drain system that is comprised of a 3'X2' trench with clean crushed sto ne, wrap with filter fabric, and a perforated collection pipe system. Figure 5 shows the proposed drainage areas that make(s) up post - development condition models. Area “10S”, area “20S”, area “30S”, area Skinner View Townhouses June 10, 2020 Northampton, Massachusetts 7 “40S”, and area “50S” are the watersheds of proposed conditions that correspond to the existing watershed areas (1, 2, 3, 4) respectively. Peaks are expected to rise due to changes in ground cover and shorter times of concentration across the paved or grassed surfaces. Analysis of the developed site is presented in pages 24-36 of the attached output pages. This corresponds to sub -areas 1 through 5 of the existing conditions analysis. In each sub -area the post-development peak is calculated to be less than the existing peak rate of runoff. This is accomplished generally by decreasing the areas, which flow is being directed off-site, and through shallow bio-retention basins. Area 10S, which corresponds to area 1S of pre-development, is 3,387 square feet of land. Runoff from this area is flowing west toward Williams Street. The size of the area is reduced, and surface ground cover will be improved. Therefore, in this area the runoff is not expected to increase, and no special mitigations are needed. Area 20S, which corresponds to area 2S of pre-development, is 2,367 square feet of land. Runoff from this area is flowing toward the adjacent neighbor on the south. The post -development area is being reduced considerably. Therefore, also in this area the runoff is not expected to increase, and no special mitigations are needed. Area 30S, which corresponds to area 3S of pre-development, is 21,778 square feet of land. This is the main area which includes the runoff from the proposed driveway and adjacent developed area. The grading of this area was designed to direct runoff into a bio-retention basin (pond 12P) through an open drainage system via sheet flow. This bio-retention is designed to improve water quality, attenuate any increase of flow due to increase of impervious areas from the main driveway and the private driveways, and promote recharge water back to the ground. The basin will be equipped with a 6" perforated PVC for subdrain, and an outlet control structure that will direct most of the water into the city's 24" RCP pipe. Sub area 31S, which a portion of it corresponds to area 3S of the pre- development, is 19,957 square feet of land. This area includes the existing barn and the studio on parcel 1, which is not part of the proposed development, and proposed to remain unchanged . Runoff from this area is currently flowing easterly toward a catch basin that is located adjacent to the barn on the easterly side and will continue to flow to this location after the proposed development. Due to a change in the grading, a relocation of the existing catch basin is being proposed at the low point of Skinner View Townhouses June 10, 2020 Northampton, Massachusetts 8 this subcatchment. Therefore, in this area the runoff is not expected to increase, and no special mitigations are needed. Area 40S, which corresponds to area 4S of pre-development, is 12,681 square feet of land. This is the main area which includes the runoff from the proposed "green area" only, which includes only the landscaped area. Runoff from this area will sheet flow to the southeasterly corner and into a wooded area. The size of the area is reduced, and s urface ground cover will be improved. Therefore, in this area the runoff is not expected to increase, and no special mitigations are needed. A grass channel is proposed on the easterly side of this subcatchment area, between the dike and the development. T his BMP will provide additional TSS removal for any snow that is stored at the end of the driveway. In order to compare with calculations for existing conditions flow to the east and into the city's 24" RCP, the total calculated peak flow reaching the underground pipe is combined in a structure named 9R in the output. The runoff from the paved driveways of area 30S will be flowing over the pavement through the grass and into the bio -retention. The bio-retention area will be constructed with a subdr ain system, that is comprised of perforated pipes embedded in crushed stone, wrapped with filter fabrics. The bio-retention will also be landscaped with planting beds, rocks, and loam areas. This system will control peak flow, bio-remedied by the stormwater, and recharge into ground water. The bio -retention is designed to be fully drained within approximately 18 hours of the storm. Landscaped area within the basin will be mowed and maintained as needed. Skinner View Townhouses June 10, 2020 Northampton, Massachusetts 9 Bio-retention Cell/Basin Detail Bioretention cells are dynamic, living, micro-ecological systems.3 They demonstrate how the landscape can be used to protect ecosystem integrity. The design of bioretention cells involve, among other things, the hydrologic cycle, nonpoint pollutant treatment, resource conservation, habitat creation, nutrient cycles, soil chemistry, horticulture, landscape architecture, and ecology3; the cell thus necessarily demonstrates a multitude of benefits. Beyond its use for stormwater control, the bioretention cell provides attractive landscaping and a natural habitat for birds and butterflies. The increased soil moisture, evapotranspiration, and vegetation coverage creates a more comfortable local climate. Bioretention cells can also be used to reduce problems with on-site erosion and high levels of flow energy. Other pollutants of concern are also addressed by the bio-retention cells. For example, sedimentation can occur in the ponding area as the velocity of the runoff slows and solids fall out of suspension. Field studies at the University of Virginia have indicated 86% removal for Total Suspended Solids (TSS), 97% for Chemical Oxygen Demand (COD), and 67% for Oil and Grease. 1 Additional work with laboratory media columns at the University of Maryland has demonstrated potential bioretention cell removal efficiencies greater than 98% for total suspended solids and oil/grease.2 1 Yu, S.L., X. Zhang, A. Earles and M. Sievers, 1999: Field testing of ultra-urban BMPs. Proceedings of the 26th Annual Water Resources Planning and Management Conference ASCE, 6-9 June, Tempe, Arizona. 2 Hsieh, C. and A.P. Davis, 2002: Engineering bioretention for treatment of urban stormwater runoff. WEF Watershed 2002 Specialty Conference, 23-27 February, Ft. Lauderdale, Florida. 3 Winogradoff, D.A. and L.S. Coffman, 1999: Bioretention water quality performance data and design modifications. Proceedings of the 26th Annual Water Resources Planning and Management Conference ASCE, June 6-9, Tempe, Arizona. Skinner View Townhouses June 10, 2020 Northampton, Massachusetts 10 V. Calculations & Design Drainage calculations were performed on HydroCAD version 7.00 using SCS TR-20 methodology and are included at the end of this report. The watershed boundaries used in these calcul ations are shown on the attached drainage maps. The permeability value as specified for Limerick and Hadley soil s is between 0.6 in/hr – 2.0 in/hr (0.00083 ft/min – 0.00278 ft/min). For a conservative measure the lowest value (0.00083 ft/min) was used i n the HydroCAD calculation for both the bio-retention basin and the filtration trench for the rooftop water. Table 1 below shows the results of the HydroCAD analysis. Curve numbers (CNs) and times of concentration for the existing and proposed subcatchment areas are based on soil types and cover conditions at the site. A multi-stage outlet structure restricts outflow from the required design storms, as shown on the detail plan. A comparison of pre- and post- development flows is shown on the following t able. Description Structure # Pre 2 year 10 year 100 year Rainfall Post 3.0" 4.5" 6.4" peak flow cfs peak flow cfs Peak flow cfs Flow to Williams St 1S existing 0.10 0.23 0.41 Flow to Williams St 10S proposed 0.09 0.21 0.37 Flow to the southern neighbor 2S existing 0.16 0.36 0.65 Flow to the southern neighbor 20SR proposed 0.01 0.05 0.14 Flow from barn area 3S existing 0.60 1.55 3.05 Flow from barn area 30S--P12 9R proposed 0.30 0.45 0.70 1.16 2.06 1.70 Flow from prop. driveway area 31S proposed 0.37 0.95 1.88 Flow from roof tops 32S--P11 proposed 0.16 0.19 0.23 Flow to South 4S existing 0.41 1.10 2.21 Flow to South 40S proposed 0.08 0.37 0.89 Table 1 Table 2 shows the bio-retention basin sizing. The sizing tool below determines the ability of the basin to process the runoff from up to 6 inches of rainfall over a 24 -hour period, which is close to 100 -year storm event. The capacity of a basin to treat runoff is considered to be a simple function of the above ground stor age volume of the cell and the infiltration Skinner View Townhouses June 10, 2020 Northampton, Massachusetts 11 volume for the soil in the cell. Factors such as rainfall intensity, infiltration rate, sloping cell sides, etc. are not considered. The volume of runoff generated for each storm event is based on the NRCS Curve Number (CN) method. An area-weighted CN is used for the drainage area. In determining this value, the actual land surface covered by the proposed bio-retention cell should be considered separately with a CN value of 98 to 100. In the context of this analysis, a surface’s CN value indicates what proportion of the rainfall does not infiltrate locally – thus, ultimately making it to the bio-retention cell for treatment. The cell itself should have a high CN value since almost all rain falling on it receives tr eatment, i.e. infiltration is into the cell’s soils and any runoff generated does not leave the depressed basin. The focus here is on infiltration and runoff volume reduction. Device Information (overwrite data in shaded cells, other cells will be automatically calculated) Controlling Area (Drainage Area)0.49995 acres =21772.8225 sq.ft. Site Condition institutional device area 2500 sq.ft.=11.5%of the site device storage depth (above ground)20 inches =1.67 ft. infiltration porosity (volume fraction of soil pores)0 **use 0 if you only want to count above-ground storage soil depth 30 inches =2.5 ft. device's total volume (above ground + soils)4166.6667 cubic ft./day Runoff Information (overwrite data in shaded cells, other cells will be automatically calculated) Land Use Impervious CN 85 S 1.76 (a)(b)(c)(d)(e)(f)(g)(h)(i)(j) Rainfall (P)Runoff (Q)Rainfall Volume Runoff Volume RunoffTreated Cumulative Probability/(e) x (g)(d) x (g)(c) x (g) (in/day)(in/day)(cu.ft. / day)(cu.ft. / day)(cu.ft. / day)Frequency Frequency (cu.ft. / day)(cu.ft. / day)(cu.ft. / day) 0.05 0.000 90.72 0.00 0.00 0.259 0.259 0.00 0.00 23.45 0.10 0.000 181.44 0.00 0.00 0.387 0.128 0.00 0.00 23.26 0.15 0.000 272.16 0.00 0.00 0.463 0.076 0.00 0.00 20.68 0.20 0.000 362.88 0.00 0.00 0.517 0.054 0.00 0.00 19.60 0.30 0.000 544.32 0.00 0.00 0.620 0.103 0.00 0.00 56.07 0.40 0.001 725.76 2.22 2.22 0.702 0.082 0.18 0.18 59.44 0.50 0.011 907.20 20.52 20.52 0.765 0.063 1.29 1.29 57.06 0.60 0.030 1088.64 55.05 55.05 0.812 0.047 2.60 2.60 51.38 0.80 0.090 1451.52 163.95 163.95 0.875 0.063 10.36 10.36 91.74 1.00 0.174 1814.40 314.98 314.98 0.918 0.044 13.70 13.70 78.93 1.25 0.302 2268.00 548.54 548.54 0.954 0.036 19.69 19.69 81.42 1.50 0.452 2721.60 819.88 819.88 0.972 0.017 14.10 14.10 46.81 2.00 0.795 3628.80 1442.69 1442.69 0.990 0.019 26.98 26.98 67.86 3.00 1.588 5443.21 2881.70 2881.70 0.997 0.007 19.60 19.60 37.01 4.00 2.458 7257.61 4459.44 4166.67 0.999 0.002 9.58 10.26 16.69 5.00 3.368 9072.01 6111.00 4166.67 1.000 0.001 2.08 3.06 4.54 6.00 4.303 10886.41 7806.50 4166.67 1.000 0.000 0.83 1.56 2.18 Total 1.000 121.00 123.38 738.12 Q Treated Q Total P Total Percent of Total Runoff Infiltrated = 98.08% LID BIORETENTION DEVICES Table 2.0 Source: 2003 Low Impact Development Center, Inc. http://www.lowimpactdevelopment.org/ Skinner View Townhouses June 10, 2020 Northampton, Massachusetts 12 VI. Summary In summary, the redevelopment of the site will mimic existing peak flow rates and volumes of runoff at the site discharge points. Stormwater mitigation measures, such as stormwater quantity and stormwater quality have been incorporated into the proposed dev elopment plan. The storm water management system has been designed so that peak flows for the 2, 10, and 100-year storms are attenuated to predevelopment practical levels with additional mitigating measures. The primary objective of the stormwater mana gement system is to control the volumes and quality of runoff being discharged to off site areas. Special care has been taken to treat runoff with a series of Best Management Practices to maintain water quality. These practices include Infiltration trenches, and bio-retention basins. Bio-retention basins will require routine periodic maintenance including inspection and repair or replacement of the treatment area's components. Bio-retention system components should blend over time through plant and root growth, organic decomposition, and the development of a natural soil horizon. These biologic and physical processes over time will lengthen the facility's life span and reduce the need for extensive maintenance. However, accumulated sediment and debris re moval (especially at the inflow point) will normally be the primary maintenance function. Other potential tasks include replacement of dead vegetation, soil pH regulation, erosion repair at inflow points, mulch replenishment, unclogging the underdrain, and repairing overflow structures. Depending on pollutant loads, soils may need to be replaced within 5 -10 years of construction. See O&M plan for specific maintenance instruction for this development. Skinner View Townhouses June 10, 2020 Northampton, Massachusetts 13 Guiding Specifications for Bioretention Drainage Area  limited to less than 1 acre Ponding Depth  maximum 6" recommended for soils with an infiltration rate of at least 2"/hr  maximum 3 to 4" recommended for soils with low infiltration rates or high hydraulic loadings (combine with a smaller drainage area)  ponding depth may be increased if using sandy soils and underdrains to increase filtration  if greenspace is limited, depth may be increased up to 1' as long as the drainage area is 1/4 acre or less  any pooled water should be drawn down within 4-6 hours after a storm event Plants  must be able to tolerate 1. expected pollutant loadings 2. highly variable soil moisture conditions 3. ponding water fluctuations  cannot be an invasive species  the use of native species is recommended  minimum recommended caliper size for trees is 1"  a minimum of 3 species of trees and 3 species of shrubs is recommended to insure diversity  avoid species that require regular maintenance Soil  homogeneous mix of o 50% construction sand o 20-30% topsoil with less than 5% maximum clay content o 20-30% organic leaf compost  pH between 5.5 and 6.5 Skinner View Townhouses June 10, 2020 Northampton, Massachusetts 14  recommended minimum depth of 2 to 2.5 feet without large tree plantings  if shallow rooted plants are used, soil depth may be reduced to 1.5 feet  recommended depth of 4 to 4.5 feet with large trees soil infiltration rate should exceed 1.5"/hr Mulch  maximum 2 to 3 inches deep  should be fresh, not aged  apply uniformly, do not pile around the base of trees  do NOT use grass clippings Groundwater  water table depth below the facility invert at l east 2' (or an underdrain may be used) Slope  if greater than 15%, technique not recommended or use a weep-garden design (see The Bioretention Manual) Pollutant Concerns  one of the primary pollutant concerns in these ultra-urban areas is metals from traffic, buildings and rooftops, downspouts, etc.  a shallow bioretention area with a full mulch layer may be used to focus on metal removal (see Watershed Benefits) Underdrain  recommended where the in-situ soil infiltration rate is less than 1"/hr (if an underdrain is not being used, soils investigation/geotechnical reports are required)  build with an accessible cleanout well  do not locate within the groundwater zone of saturation  must have a hydraulic capacity greater than the planting soil infiltration rate  may outfall to a suitable location such as common space area, stream valley, drainage swale, roadside open-section, or existing enclosed drainage system Surface Overflow  design for overflow is necessary if drainage areas in commercial and institutional settings are highly impervious Skinner View Townhouses June 10, 2020 Northampton, Massachusetts 15 Inflow  special design considerations are necessary to direct the impervious drainage area's runoff to the bio-retention cell  water may be diverted into the bio-retention area through the use of an inlet deflector block, which has ridges to channel the runoff into the cell  in a paved area with no curb, pre-cast car stops can be installed along the pavement perimeter to protect the bio-retention area  paved lot runoff may be captured through the use of vegetated soil/gravel trenches integrated into the paved area at strategic locations  drainage dispersion techniques may also need to be used for highly impervious drainage areas  when inflow exceeds 3 cfs the designer should evaluate the potential for erosion Location  avoid locating the bio-retention cell near building areas, well heads, and septic systems  locate away from traveled areas such as public pathways to avoid compaction Source: 2003 Low Impact Development Center, Inc. http://www.lowimpactdevelopment.org/ Skinner View Townhouses June 10, 2020 Northampton, Massachusetts 16 Proposed Stormwater Management System Operation & Maintenance Plan During Construction The Contractor shall be responsible for inspection and maintenance during construction. At all times, stakes and hay bales sufficient to construct a sedimentation control barrier a minimum of 20 feet long will be stockpiled on the site in order to repair any established barriers which may have been 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 rainstorms 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 rainstorm shall be defined as all or one of the following:  Any storm in which rain is predicted to last for 12 consecutive hours or more.  Any storm for which a flash flood watch or warning is issued.  Any single storm predicted to have a cumulative rainfall of greater than 0.5”  Any 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 significant. 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 Contractor shall remove the sediment from behind the hay bale fence of any sedimentation control barrier when the accumulated sediment has reached one-half of the original installed height of the barrier. Skinner View Townhouses June 10, 2020 Northampton, Massachusetts 17 Post-Construction Stormwater Management System Owner: Skinner View Townhouses Address Northampton, Massachusetts 01060 Telephone No. Party Responsible for Operation & Maintenance: Skinner View Townhouses Address Northampton, Massachusetts 01060 Telephone No. Inspection & Maintenance Schedule: 1) Bioretention Basin/Cell Soil  Visually inspect and repair erosion monthly. Use small stones to stabilize erosion along drainage paths.  Check the pH once or twice a year. Apply an alkaline product, such as limestone, if needed. Mulch  Re-mulch any void areas by hand as needed.  Every 6 months, in the spring and fall, add a fresh mulch layer.  Once every 2 to 3 years, in the spring, remove old mulch layer before applying new one. Plants  Immediately after the completion of cell construction, water plant material for 14 consecutive days unless there is sufficient natural rainfall.  After trees have taken root, or at least by 6 months, remove stakes and wires.  Once a month (more frequently in the summer), visually inspect vegetation for disease or pest problems.  If treatment is warranted, use the least toxic approach.  Twice a year, from March 15th to April 30th and October 1st to November 30th, remove and replace all dead and diseased vegetation considered beyond treatment.  During times of extended drought, look for physical features of stress (unrevived wilting, yellow, spotted or brown leaves, loss of leaves, etc.). Water in the early morning as needed.  Weed regularly, if needed.  Prune excess growth annually or more often, if desired. Trimmed materials may be recycled back in with replenished mulch or land filled if there is a concern of heavy metals accumulation. General  After rainstorms, inspect the cell and make sure that drainage paths are clear, and that ponding water dissipates over 4-6 hours. (Water may pond for longer times during the winter and early spring.)  KEEP IN MIND, THE BIORETENTION CELL IS NOT A POND. IT SHOULD NOT PROVIDE A BREEDING GROUND FOR MOSQUITOES. MOSQUITOES NEED AT LEAST 4 DAYS OF STANDING WATER TO DEVELOP AS LARVA. 3) Infiltration Trench The infiltration trench requires very minimal routine maintenance; however, it is important that the system would be properly inspected at least once per year. The infiltration pipe shall be inspected from both ends for any accumulation of sediments. If observable sediment is accumulated at the bottom of the pipe, the pipe should be hosed down with pressurized water through a cleanout port. 5) General  The contractor/owner shall be responsible for inspection and maintenance during construction and up until the development is accepted by the condominium association.  Existing Catch basin shall be protected from excessive siltation by placing silt sacks, “tea bags”, or silt fabric between CB cover and frame until the site is stabilized and vegetative cover is well established.  Pavement at all entrances shall be swept clean of silt and debris as needed. Skinner View Townhouses June 10, 2020 Northampton, Massachusetts 20 USGS Soils Data Map Unit Description 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 in this report, 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. With in 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 miscel laneous areas for which it is named, soils that are similar to the named components, and some minor components that differ in use and management from the major soils. Most of the soils similar to the major components 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. Some minor components, however, have pr operties and behavior characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is plann ed, 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. All the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of a given series can differ in texture of t he 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 ar eas. 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 a nd 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 in terpretations 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. Skinner View Townhouses June 10, 2020 Northampton, Massachusetts 22 Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. Additional information about the map uni ts described in this report is available in other soil reports, which give properties of the soils and the limitations, capabilities, and potentials for many uses. Also, the narratives that accompany the soil reports define some of the properties included in the map unit descriptions. Hampshire County, Massachusetts, Central Part 8A—Limerick silt loam, 0 to 3 percent slopes Map Unit Setting National map unit symbol: 9b0f Elevation: 50 to 500 feet Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 45 to 52 degrees F Frost-free period: 140 to 240 days Farmland classification: Not prime farmland Map Unit Composition Limerick and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Limerick Setting Landform: Alluvial flats Landform position (three-dimensional): Dip Down-slope shape: Linear Across-slope shape: Linear Parent material: Silty alluvium Typical profile H1 - 0 to 12 inches: silt loam H2 - 12 to 20 inches: very fine sandy loam H3 - 20 to 60 inches: silt loam Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Poorly drained Runoff class: Very high Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high (0.60 to 2.00 in/hr) Depth to water table: About 0 to 18 inches Frequency of flooding: Frequent Frequency of ponding: None Available water storage in profile: Very high (about 13.4 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 3w Hydrologic Soil Group: B/D Hydric soil rating: Yes Minor Components Winooski Percent of map unit: 10 percent Hydric soil rating: No Skinner View Townhouses June 10, 2020 Northampton, Massachusetts 23 Saco Percent of map unit: 5 percent Landform: Alluvial flats Hydric soil rating: Yes Hampshire County, Massachusetts, Central Part 744A—Hadley-Winooski-Urban land complex, 0 to 3 percent slopes Map Unit Setting National map unit symbol: 9b03 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 Hadley and similar soils: 45 percent Winooski and similar soils: 20 percent Urban land: 20 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Hadley Setting Landform: Flood plains Landform position (two-dimensional): Toeslope Landform position (three-dimensional): Tread Down-slope shape: Linear Across-slope shape: Linear Parent material: Friable coarse-silty alluvium Typical profile H1 - 0 to 11 inches: silt loam H2 - 11 to 68 inches: silt loam H3 - 68 to 72 inches: loamy fine sand Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Well drained Runoff class: Low Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high (0.60 to 2.00 in/hr) Depth to water table: About 48 to 72 inches Frequency of flooding: Occasional Frequency of ponding: None Available water storage in profile: High (about 10.5 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 1 Hydrologic Soil Group: B Hydric soil rating: No Description of Urban Land Setting Parent material: Paved/filled Skinner View Townhouses June 10, 2020 Northampton, Massachusetts 24 Description of Winooski Setting Landform: Flood plains Landform position (two-dimensional): Toeslope Landform position (three-dimensional): Tread Down-slope shape: Linear Across-slope shape: Linear Parent material: Silty alluvium Typical profile H1 - 0 to 17 inches: silt loam H2 - 17 to 60 inches: silt loam Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Moderately well drained Runoff class: Very low Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high (0.60 to 6.00 in/hr) Depth to water table: About 18 to 36 inches Frequency of flooding: Occasional Frequency of ponding: None Available water storage in profile: High (about 10.5 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 2w Hydrologic Soil Group: B Hydric soil rating: No Minor Components Limerick Percent of map unit: 10 percent Landform: Alluvial flats Hydric soil rating: Yes Saco Percent of map unit: 5 percent Landform: Alluvial flats Hydric soil rating: Yes Data Source Information Soil Survey Area: Hampshire County, Massachusetts, Central Part Survey Area Data: Version 14, Sep 13, 2019 Drainage Diagram for 30Will-Ex Prepared by Sharff Group, LTD 24/06/2020 HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcat Reach Pond Link 1S Williams Frontage 2S Southern Neighbor 3S Barn area 4S Southern parcel side Type III 24-hr 2YR Rainfall=3.00"30Will-Ex Page 26Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=3,742 sf Runoff Depth=0.96"Subcatchment 1S: Williams Frontage Tc=1.1 min CN=75 Runoff=0.10 cfs 0.007 af Runoff Area=5,930 sf Runoff Depth=0.96"Subcatchment 2S: Southern Neighbor Tc=2.2 min CN=75 Runoff=0.16 cfs 0.011 af Runoff Area=32,438 sf Runoff Depth=0.71"Subcatchment 3S: Barn area Tc=2.9 min CN=70 Runoff=0.60 cfs 0.044 af Runoff Area=23,011 sf Runoff Depth=0.67"Subcatchment 4S: Southern parcel side Tc=0.0 min CN=69 Runoff=0.41 cfs 0.029 af Total Runoff Area = 1.495 ac Runoff Volume = 0.092 af Average Runoff Depth = 0.73" Type III 24-hr 2YR Rainfall=3.00"30Will-Ex Page 27Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 1S: Williams Frontage [49] Hint: Tc<2dt may require smaller dt Runoff = 0.10 cfs @ 12.03 hrs, Volume= 0.007 af, Depth= 0.96" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2YR Rainfall=3.00" Area (sf) CN Description 3,742 75 1/4 acre lots, 38% imp, HSG B Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.1 Direct Entry, calculated Subcatchment 1S: Williams Frontage Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.11 0.105 0.1 0.095 0.09 0.085 0.08 0.075 0.07 0.065 0.06 0.055 0.05 0.045 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0 Type III 24-hr 2YR Rainfall=3.00" Runoff Area=3,742 sf Runoff Volume=0.007 af Runoff Depth=0.96" Tc=1.1 min CN=75 0.10 cfs Type III 24-hr 2YR Rainfall=3.00"30Will-Ex Page 28Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 2S: Southern Neighbor [49] Hint: Tc<2dt may require smaller dt Runoff = 0.16 cfs @ 12.05 hrs, Volume= 0.011 af, Depth= 0.96" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2YR Rainfall=3.00" Area (sf) CN Description 5,930 75 1/4 acre lots, 38% imp, HSG B Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.2 Direct Entry, Calculated Subcatchment 2S: Southern Neighbor Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.18 0.17 0.16 0.15 0.14 0.13 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Type III 24-hr 2YR Rainfall=3.00" Runoff Area=5,930 sf Runoff Volume=0.011 af Runoff Depth=0.96" Tc=2.2 min CN=75 0.16 cfs Type III 24-hr 2YR Rainfall=3.00"30Will-Ex Page 29Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 3S: Barn area [49] Hint: Tc<2dt may require smaller dt Runoff = 0.60 cfs @ 12.06 hrs, Volume= 0.044 af, Depth= 0.71" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2YR Rainfall=3.00" Area (sf) CN Description 32,438 70 1/2 acre lots, 25% imp, HSG B Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.9 Direct Entry, Calculated Subcatchment 3S: Barn area Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Type III 24-hr 2YR Rainfall=3.00" Runoff Area=32,438 sf Runoff Volume=0.044 af Runoff Depth=0.71" Tc=2.9 min CN=70 0.60 cfs Type III 24-hr 2YR Rainfall=3.00"30Will-Ex Page 30Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 4S: Southern parcel side [46] Hint: Tc=0 (Instant runoff peak depends on dt) Runoff = 0.41 cfs @ 12.01 hrs, Volume= 0.029 af, Depth= 0.67" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2YR Rainfall=3.00" Area (sf) CN Description 23,011 69 50-75% Grass cover, Fair, HSG B Subcatchment 4S: Southern parcel side Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.44 0.42 0.4 0.38 0.36 0.34 0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Type III 24-hr 2YR Rainfall=3.00" Runoff Area=23,011 sf Runoff Volume=0.029 af Runoff Depth=0.67" Tc=0.0 min CN=69 0.41 cfs Type III 24-hr 10YR Rainfall=4.50"30Will-Ex Page 31Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=3,742 sf Runoff Depth=2.05"Subcatchment 1S: Williams Frontage Tc=1.1 min CN=75 Runoff=0.23 cfs 0.015 af Runoff Area=5,930 sf Runoff Depth=2.05"Subcatchment 2S: Southern Neighbor Tc=2.2 min CN=75 Runoff=0.36 cfs 0.023 af Runoff Area=32,438 sf Runoff Depth=1.67"Subcatchment 3S: Barn area Tc=2.9 min CN=70 Runoff=1.55 cfs 0.104 af Runoff Area=23,011 sf Runoff Depth=1.60"Subcatchment 4S: Southern parcel side Tc=0.0 min CN=69 Runoff=1.10 cfs 0.071 af Total Runoff Area = 1.495 ac Runoff Volume = 0.212 af Average Runoff Depth = 1.70" Type III 24-hr 10YR Rainfall=4.50"30Will-Ex Page 32Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 1S: Williams Frontage [49] Hint: Tc<2dt may require smaller dt Runoff = 0.23 cfs @ 12.02 hrs, Volume= 0.015 af, Depth= 2.05" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10YR Rainfall=4.50" Area (sf) CN Description 3,742 75 1/4 acre lots, 38% imp, HSG B Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.1 Direct Entry, calculated Subcatchment 1S: Williams Frontage Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.25 0.24 0.23 0.22 0.21 0.2 0.19 0.18 0.17 0.16 0.15 0.14 0.13 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Type III 24-hr 10YR Rainfall=4.50" Runoff Area=3,742 sf Runoff Volume=0.015 af Runoff Depth=2.05" Tc=1.1 min CN=75 0.23 cfs Type III 24-hr 10YR Rainfall=4.50"30Will-Ex Page 33Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 2S: Southern Neighbor [49] Hint: Tc<2dt may require smaller dt Runoff = 0.36 cfs @ 12.04 hrs, Volume= 0.023 af, Depth= 2.05" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10YR Rainfall=4.50" Area (sf) CN Description 5,930 75 1/4 acre lots, 38% imp, HSG B Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.2 Direct Entry, Calculated Subcatchment 2S: Southern Neighbor Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.4 0.38 0.36 0.34 0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Type III 24-hr 10YR Rainfall=4.50" Runoff Area=5,930 sf Runoff Volume=0.023 af Runoff Depth=2.05" Tc=2.2 min CN=75 0.36 cfs Type III 24-hr 10YR Rainfall=4.50"30Will-Ex Page 34Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 3S: Barn area [49] Hint: Tc<2dt may require smaller dt Runoff = 1.55 cfs @ 12.05 hrs, Volume= 0.104 af, Depth= 1.67" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10YR Rainfall=4.50" Area (sf) CN Description 32,438 70 1/2 acre lots, 25% imp, HSG B Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.9 Direct Entry, Calculated Subcatchment 3S: Barn area Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Type III 24-hr 10YR Rainfall=4.50" Runoff Area=32,438 sf Runoff Volume=0.104 af Runoff Depth=1.67" Tc=2.9 min CN=70 1.55 cfs Type III 24-hr 10YR Rainfall=4.50"30Will-Ex Page 35Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 4S: Southern parcel side [46] Hint: Tc=0 (Instant runoff peak depends on dt) Runoff = 1.10 cfs @ 12.01 hrs, Volume= 0.071 af, Depth= 1.60" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10YR Rainfall=4.50" Area (sf) CN Description 23,011 69 50-75% Grass cover, Fair, HSG B Subcatchment 4S: Southern parcel side Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Type III 24-hr 10YR Rainfall=4.50" Runoff Area=23,011 sf Runoff Volume=0.071 af Runoff Depth=1.60" Tc=0.0 min CN=69 1.10 cfs Type III 24-hr 100YR Rainfall=6.50"30Will-Ex Page 36Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=3,742 sf Runoff Depth=3.71"Subcatchment 1S: Williams Frontage Tc=1.1 min CN=75 Runoff=0.41 cfs 0.027 af Runoff Area=5,930 sf Runoff Depth=3.71"Subcatchment 2S: Southern Neighbor Tc=2.2 min CN=75 Runoff=0.65 cfs 0.042 af Runoff Area=32,438 sf Runoff Depth=3.21"Subcatchment 3S: Barn area Tc=2.9 min CN=70 Runoff=3.05 cfs 0.199 af Runoff Area=23,011 sf Runoff Depth=3.11"Subcatchment 4S: Southern parcel side Tc=0.0 min CN=69 Runoff=2.21 cfs 0.137 af Total Runoff Area = 1.495 ac Runoff Volume = 0.404 af Average Runoff Depth = 3.25" Type III 24-hr 100YR Rainfall=6.50"30Will-Ex Page 37Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 1S: Williams Frontage [49] Hint: Tc<2dt may require smaller dt Runoff = 0.41 cfs @ 12.02 hrs, Volume= 0.027 af, Depth= 3.71" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100YR Rainfall=6.50" Area (sf) CN Description 3,742 75 1/4 acre lots, 38% imp, HSG B Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.1 Direct Entry, calculated Subcatchment 1S: Williams Frontage Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.46 0.44 0.42 0.4 0.38 0.36 0.34 0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Type III 24-hr 100YR Rainfall=6.50" Runoff Area=3,742 sf Runoff Volume=0.027 af Runoff Depth=3.71" Tc=1.1 min CN=75 0.41 cfs Type III 24-hr 100YR Rainfall=6.50"30Will-Ex Page 38Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 2S: Southern Neighbor [49] Hint: Tc<2dt may require smaller dt Runoff = 0.65 cfs @ 12.04 hrs, Volume= 0.042 af, Depth= 3.71" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100YR Rainfall=6.50" Area (sf) CN Description 5,930 75 1/4 acre lots, 38% imp, HSG B Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.2 Direct Entry, Calculated Subcatchment 2S: Southern Neighbor Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Type III 24-hr 100YR Rainfall=6.50" Runoff Area=5,930 sf Runoff Volume=0.042 af Runoff Depth=3.71" Tc=2.2 min CN=75 0.65 cfs Type III 24-hr 100YR Rainfall=6.50"30Will-Ex Page 39Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 3S: Barn area [49] Hint: Tc<2dt may require smaller dt Runoff = 3.05 cfs @ 12.05 hrs, Volume= 0.199 af, Depth= 3.21" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100YR Rainfall=6.50" Area (sf) CN Description 32,438 70 1/2 acre lots, 25% imp, HSG B Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.9 Direct Entry, Calculated Subcatchment 3S: Barn area Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)3 2 1 0 Type III 24-hr 100YR Rainfall=6.50" Runoff Area=32,438 sf Runoff Volume=0.199 af Runoff Depth=3.21" Tc=2.9 min CN=70 3.05 cfs Type III 24-hr 100YR Rainfall=6.50"30Will-Ex Page 40Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 4S: Southern parcel side [46] Hint: Tc=0 (Instant runoff peak depends on dt) Runoff = 2.21 cfs @ 12.01 hrs, Volume= 0.137 af, Depth= 3.11" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100YR Rainfall=6.50" Area (sf) CN Description 23,011 69 50-75% Grass cover, Fair, HSG B Subcatchment 4S: Southern parcel side Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)2 1 0 Type III 24-hr 100YR Rainfall=6.50" Runoff Area=23,011 sf Runoff Volume=0.137 af Runoff Depth=3.11" Tc=0.0 min CN=69 2.21 cfs Drainage Diagram for 30Will-Prop Prepared by Sharff Group, LTD 24/06/2020 HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcat Reach Pond Link 10S Williams Frontage 20S Southern Neighbor 30S Main area 31S Barn area 32S Roof Tops of Duplexes 40S Southern parcel side 9R Existing 24" Drain 11P Duplexes Perimeter Subdrain for Rooftop 12P Bio Retension Pond Type III 24-hr 2YR Rainfall=3.00"30Will-Prop Page 42Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=3,387 sf Runoff Depth=0.96"Subcatchment 10S: Williams Frontage Tc=1.1 min CN=75 Runoff=0.09 cfs 0.006 af Runoff Area=2,367 sf Runoff Depth=0.27"Subcatchment 20S: Southern Neighbor Tc=2.2 min CN=58 Runoff=0.01 cfs 0.001 af Runoff Area=21,778 sf Runoff Depth=0.86"Subcatchment 30S: Main area Tc=2.0 min CN=73 Runoff=0.52 cfs 0.036 af Runoff Area=19,957 sf Runoff Depth=0.71"Subcatchment 31S: Barn area Tc=2.9 min CN=70 Runoff=0.37 cfs 0.027 af Runoff Area=8,850 sf Runoff Depth=2.77"Subcatchment 32S: Roof Tops of Duplexes Tc=0.0 min CN=98 Runoff=0.68 cfs 0.047 af Runoff Area=12,681 sf Runoff Depth=0.37"Subcatchment 40S: Southern parcel side Tc=0.0 min CN=61 Runoff=0.08 cfs 0.009 af Peak Depth=0.72' Max Vel=0.4 fps Inflow=0.60 cfs 0.098 afReach 9R: Existing 24" Drain D=24.0" n=0.015 L=300.0' S=0.0001 '/' Capacity=1.60 cfs Outflow=0.45 cfs 0.097 af Peak Elev=88.19' Storage=430 cf Inflow=0.68 cfs 0.047 afPond 11P: Duplexes Perimeter Subdrain for Ro Primary=0.14 cfs 0.039 af Secondary=0.02 cfs 0.008 af Outflow=0.16 cfs 0.047 af Peak Elev=86.74' Storage=373 cf Inflow=0.64 cfs 0.075 afPond 12P: Bio Retension Pond Primary=0.30 cfs 0.071 af Secondary=0.00 cfs 0.004 af Outflow=0.30 cfs 0.074 af Total Runoff Area = 1.584 ac Runoff Volume = 0.126 af Average Runoff Depth = 0.96" Type III 24-hr 2YR Rainfall=3.00"30Will-Prop Page 43Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 10S: Williams Frontage [49] Hint: Tc<2dt may require smaller dt Runoff = 0.09 cfs @ 12.03 hrs, Volume= 0.006 af, Depth= 0.96" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2YR Rainfall=3.00" Area (sf) CN Description 3,387 75 1/4 acre lots, 38% imp, HSG B Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.1 Direct Entry, calculated Subcatchment 10S: Williams Frontage Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.1 0.095 0.09 0.085 0.08 0.075 0.07 0.065 0.06 0.055 0.05 0.045 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0 Type III 24-hr 2YR Rainfall=3.00" Runoff Area=3,387 sf Runoff Volume=0.006 af Runoff Depth=0.96" Tc=1.1 min CN=75 0.09 cfs Type III 24-hr 2YR Rainfall=3.00"30Will-Prop Page 44Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 20S: Southern Neighbor [49] Hint: Tc<2dt may require smaller dt Runoff = 0.01 cfs @ 12.12 hrs, Volume= 0.001 af, Depth= 0.27" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2YR Rainfall=3.00" Area (sf) CN Description 2,367 58 Woods/grass comb., Good, HSG B Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.2 Direct Entry, Calculated Subcatchment 20S: Southern Neighbor Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.008 0.007 0.007 0.006 0.006 0.005 0.005 0.004 0.004 0.003 0.003 0.002 0.002 0.001 0.001 0.000 0 Type III 24-hr 2YR Rainfall=3.00" Runoff Area=2,367 sf Runoff Volume=0.001 af Runoff Depth=0.27" Tc=2.2 min CN=58 0.01 cfs Type III 24-hr 2YR Rainfall=3.00"30Will-Prop Page 45Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 30S: Main area [49] Hint: Tc<2dt may require smaller dt Runoff = 0.52 cfs @ 12.05 hrs, Volume= 0.036 af, Depth= 0.86" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2YR Rainfall=3.00" Area (sf) CN Description 14,928 61 >75% Grass cover, Good, HSG B 4,495 98 Paved roofs 2,355 98 Driveways 21,778 73 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.0 Direct Entry, Subcatchment 30S: Main area Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Type III 24-hr 2YR Rainfall=3.00" Runoff Area=21,778 sf Runoff Volume=0.036 af Runoff Depth=0.86" Tc=2.0 min CN=73 0.52 cfs Type III 24-hr 2YR Rainfall=3.00"30Will-Prop Page 46Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 31S: Barn area [49] Hint: Tc<2dt may require smaller dt Runoff = 0.37 cfs @ 12.06 hrs, Volume= 0.027 af, Depth= 0.71" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2YR Rainfall=3.00" Area (sf) CN Description 19,957 70 1/2 acre lots, 25% imp, HSG B Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.9 Direct Entry, Calculated Subcatchment 31S: Barn area Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.4 0.38 0.36 0.34 0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Type III 24-hr 2YR Rainfall=3.00" Runoff Area=19,957 sf Runoff Volume=0.027 af Runoff Depth=0.71" Tc=2.9 min CN=70 0.37 cfs Type III 24-hr 2YR Rainfall=3.00"30Will-Prop Page 47Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 32S: Roof Tops of Duplexes [46] Hint: Tc=0 (Instant runoff peak depends on dt) Runoff = 0.68 cfs @ 12.00 hrs, Volume= 0.047 af, Depth= 2.77" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2YR Rainfall=3.00" Area (sf) CN Description 3,101 98 roofs 3,101 98 roofs 1,324 98 roofs 1,324 98 roofs 8,850 98 Weighted Average Subcatchment 32S: Roof Tops of Duplexes Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Type III 24-hr 2YR Rainfall=3.00" Runoff Area=8,850 sf Runoff Volume=0.047 af Runoff Depth=2.77" Tc=0.0 min CN=98 0.68 cfs Type III 24-hr 2YR Rainfall=3.00"30Will-Prop Page 48Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 40S: Southern parcel side [46] Hint: Tc=0 (Instant runoff peak depends on dt) Runoff = 0.08 cfs @ 12.05 hrs, Volume= 0.009 af, Depth= 0.37" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2YR Rainfall=3.00" Area (sf) CN Description 12,681 61 >75% Grass cover, Good, HSG B Subcatchment 40S: Southern parcel side Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.085 0.08 0.075 0.07 0.065 0.06 0.055 0.05 0.045 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0 Type III 24-hr 2YR Rainfall=3.00" Runoff Area=12,681 sf Runoff Volume=0.009 af Runoff Depth=0.37" Tc=0.0 min CN=61 0.08 cfs Type III 24-hr 2YR Rainfall=3.00"30Will-Prop Page 49Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Reach 9R: Existing 24" Drain [52] Hint: Inlet conditions not evaluated [79] Warning: Submerged Pond 12P Primary device # 1 INLET by 0.72' Inflow Area = 1.161 ac, Inflow Depth = 1.01" for 2YR event Inflow = 0.60 cfs @ 12.07 hrs, Volume= 0.098 af Outflow = 0.45 cfs @ 12.52 hrs, Volume= 0.097 af, Atten= 25%, Lag= 27.3 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs / 3 Max. Velocity= 0.4 fps, Min. Travel Time= 11.4 min Avg. Velocity = 0.2 fps, Avg. Travel Time= 26.6 min Peak Depth= 0.72' @ 12.33 hrs Capacity at bank full= 1.60 cfs Inlet Invert= 79.60', Outlet Invert= 79.58' 24.0" Diameter Pipe n= 0.015 Length= 300.0' Slope= 0.0001 '/' Reach 9R: Existing 24" Drain Inflow Outflow Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Inflow Area=1.161 ac Peak Depth=0.72' Max Vel=0.4 fps D=24.0" n=0.015 L=300.0' S=0.0001 '/' Capacity=1.60 cfs 0.60 cfs 0.45 cfs Type III 24-hr 2YR Rainfall=3.00"30Will-Prop Page 50Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Pond 11P: Duplexes Perimeter Subdrain for Rooftop Inflow Area = 0.203 ac, Inflow Depth = 2.77" for 2YR event Inflow = 0.68 cfs @ 12.00 hrs, Volume= 0.047 af Outflow = 0.16 cfs @ 12.34 hrs, Volume= 0.047 af, Atten= 76%, Lag= 20.3 min Primary = 0.14 cfs @ 12.34 hrs, Volume= 0.039 af Secondary = 0.02 cfs @ 11.65 hrs, Volume= 0.008 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 88.19' @ 12.34 hrs Surf.Area= 1,548 sf Storage= 430 cf Plug-Flow detention time= 15.6 min calculated for 0.047 af (100% of inflow) Center-of-Mass det. time= 15.3 min ( 767.6 - 752.2 ) # Invert Avail.Storage Storage Description 1 87.50' 1,858 cf Custom Stage Data (Prismatic) Listed below x 3 Elevation Surf.Area Voids Inc.Store Cum.Store (feet) (sq-ft) (%) (cubic-feet) (cubic-feet) 87.50 516 40.0 0 0 90.50 516 40.0 619 619 # Routing Invert Outlet Devices 1 Primary 87.00'4.0" x 100.0' long Culvert X 2.00 CMP, projecting, no headwall, Ke= 0.900 Outlet Invert= 86.00' S= 0.0100 '/' n= 0.013 Cc= 0.900 2 Device 1 87.00'0.4" Horiz. Orifice/Grate X 30.00 Limited to weir flow C= 0.600 3 Secondary 0.00'0.000830 fpm Exfiltration over entire Surface area Primary OutFlow Max=0.14 cfs @ 12.34 hrs HW=88.19' (Free Discharge) 1=Culvert (Passes 0.14 cfs of 0.49 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.14 cfs @ 5.3 fps) Secondary OutFlow Max=0.02 cfs @ 11.65 hrs HW=87.54' (Free Discharge) 3=Exfiltration (Exfiltration Controls 0.02 cfs) Type III 24-hr 2YR Rainfall=3.00"30Will-Prop Page 51Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Pond 11P: Duplexes Perimeter Subdrain for Rooftop Inflow Outflow Primary Secondary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Inflow Area=0.203 ac Peak Elev=88.19' Storage=430 cf 0.68 cfs 0.16 cfs 0.14 cfs 0.02 cfs Type III 24-hr 2YR Rainfall=3.00"30Will-Prop Page 52Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Pond 12P: Bio Retension Pond [79] Warning: Submerged Pond 11P Primary device # 1 OUTLET by 0.74' Inflow Area = 0.703 ac, Inflow Depth = 1.27" for 2YR event Inflow = 0.64 cfs @ 12.05 hrs, Volume= 0.075 af Outflow = 0.30 cfs @ 12.39 hrs, Volume= 0.074 af, Atten= 53%, Lag= 20.5 min Primary = 0.30 cfs @ 12.39 hrs, Volume= 0.071 af Secondary = 0.00 cfs @ 11.30 hrs, Volume= 0.004 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs / 2 Peak Elev= 86.74' @ 12.39 hrs Surf.Area= 300 sf Storage= 373 cf Plug-Flow detention time= 9.8 min calculated for 0.074 af (100% of inflow) Center-of-Mass det. time= 9.5 min ( 824.1 - 814.6 ) # Invert Avail.Storage Storage Description 1 85.00' 2,047 cf Custom Stage Data (Irregular) Listed below Elevation Surf.Area Perim. Voids Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (feet) (%) (cubic-feet) (cubic-feet) (sq-ft) 85.00 300 87.0 40.0 0 0 300 86.00 300 87.0 50.0 150 150 387 87.00 300 87.6 100.0 300 450 475 88.00 669 144.1 100.0 472 922 1,523 89.00 1,654 312.5 100.0 1,125 2,047 7,646 # Routing Invert Outlet Devices 1 Primary 79.60'24.0" x 300.0' long Culvert RCP, rounded edge headwall, Ke= 0.100 Outlet Invert= 79.58' S= 0.0001 '/' n= 0.015 Cc= 0.900 2 Secondary 0.00'0.000830 fpm Exfiltration over entire Surface area 3 Device 1 87.90'24.0" Horiz. Orifice/Grate Limited to weir flow C= 0.600 4 Device 1 85.00'0.4" Horiz. Perferatef subdrain X 50.00 Limited to weir flow C= 0.600 5 Device 1 86.65'4.0" Vert. Orifice/Grate C= 0.600 Primary OutFlow Max=0.30 cfs @ 12.39 hrs HW=86.74' (Free Discharge) 1=Culvert (Passes 0.30 cfs of 23.24 cfs potential flow) 3=Orifice/Grate ( Controls 0.00 cfs) 4=Perferatef subdrain (Orifice Controls 0.28 cfs @ 6.4 fps) 5=Orifice/Grate (Orifice Controls 0.02 cfs @ 1.0 fps) Secondary OutFlow Max=0.00 cfs @ 11.30 hrs HW=85.04' (Free Discharge) 2=Exfiltration (Exfiltration Controls 0.00 cfs) Type III 24-hr 2YR Rainfall=3.00"30Will-Prop Page 53Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Pond 12P: Bio Retension Pond Inflow Outflow Primary Secondary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Inflow Area=0.703 ac Peak Elev=86.74' Storage=373 cf 0.64 cfs 0.30 cfs 0.30 cfs 0.00 cfs Type III 24-hr 10YR Rainfall=4.50"30Will-Prop Page 54Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=3,387 sf Runoff Depth=2.05"Subcatchment 10S: Williams Frontage Tc=1.1 min CN=75 Runoff=0.21 cfs 0.013 af Runoff Area=2,367 sf Runoff Depth=0.90"Subcatchment 20S: Southern Neighbor Tc=2.2 min CN=58 Runoff=0.05 cfs 0.004 af Runoff Area=21,778 sf Runoff Depth=1.90"Subcatchment 30S: Main area Tc=2.0 min CN=73 Runoff=1.21 cfs 0.079 af Runoff Area=19,957 sf Runoff Depth=1.67"Subcatchment 31S: Barn area Tc=2.9 min CN=70 Runoff=0.95 cfs 0.064 af Runoff Area=8,850 sf Runoff Depth=4.26"Subcatchment 32S: Roof Tops of Duplexes Tc=0.0 min CN=98 Runoff=1.02 cfs 0.072 af Runoff Area=12,681 sf Runoff Depth=1.08"Subcatchment 40S: Southern parcel side Tc=0.0 min CN=61 Runoff=0.37 cfs 0.026 af Peak Depth=1.26' Max Vel=0.6 fps Inflow=1.56 cfs 0.199 afReach 9R: Existing 24" Drain D=24.0" n=0.015 L=300.0' S=0.0001 '/' Capacity=1.60 cfs Outflow=1.16 cfs 0.197 af Peak Elev=88.79' Storage=799 cf Inflow=1.02 cfs 0.072 afPond 11P: Duplexes Perimeter Subdrain for Ro Primary=0.17 cfs 0.061 af Secondary=0.02 cfs 0.012 af Outflow=0.19 cfs 0.072 af Peak Elev=87.53' Storage=700 cf Inflow=1.36 cfs 0.140 afPond 12P: Bio Retension Pond Primary=0.69 cfs 0.135 af Secondary=0.01 cfs 0.005 af Outflow=0.70 cfs 0.140 af Total Runoff Area = 1.584 ac Runoff Volume = 0.259 af Average Runoff Depth = 1.96" Type III 24-hr 10YR Rainfall=4.50"30Will-Prop Page 55Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 10S: Williams Frontage [49] Hint: Tc<2dt may require smaller dt Runoff = 0.21 cfs @ 12.02 hrs, Volume= 0.013 af, Depth= 2.05" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10YR Rainfall=4.50" Area (sf) CN Description 3,387 75 1/4 acre lots, 38% imp, HSG B Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.1 Direct Entry, calculated Subcatchment 10S: Williams Frontage Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.22 0.21 0.2 0.19 0.18 0.17 0.16 0.15 0.14 0.13 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Type III 24-hr 10YR Rainfall=4.50" Runoff Area=3,387 sf Runoff Volume=0.013 af Runoff Depth=2.05" Tc=1.1 min CN=75 0.21 cfs Type III 24-hr 10YR Rainfall=4.50"30Will-Prop Page 56Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 20S: Southern Neighbor [49] Hint: Tc<2dt may require smaller dt Runoff = 0.05 cfs @ 12.06 hrs, Volume= 0.004 af, Depth= 0.90" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10YR Rainfall=4.50" Area (sf) CN Description 2,367 58 Woods/grass comb., Good, HSG B Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.2 Direct Entry, Calculated Subcatchment 20S: Southern Neighbor Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.055 0.05 0.045 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0 Type III 24-hr 10YR Rainfall=4.50" Runoff Area=2,367 sf Runoff Volume=0.004 af Runoff Depth=0.90" Tc=2.2 min CN=58 0.05 cfs Type III 24-hr 10YR Rainfall=4.50"30Will-Prop Page 57Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 30S: Main area [49] Hint: Tc<2dt may require smaller dt Runoff = 1.21 cfs @ 12.04 hrs, Volume= 0.079 af, Depth= 1.90" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10YR Rainfall=4.50" Area (sf) CN Description 14,928 61 >75% Grass cover, Good, HSG B 4,495 98 Paved roofs 2,355 98 Driveways 21,778 73 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.0 Direct Entry, Subcatchment 30S: Main area Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Type III 24-hr 10YR Rainfall=4.50" Runoff Area=21,778 sf Runoff Volume=0.079 af Runoff Depth=1.90" Tc=2.0 min CN=73 1.21 cfs Type III 24-hr 10YR Rainfall=4.50"30Will-Prop Page 58Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 31S: Barn area [49] Hint: Tc<2dt may require smaller dt Runoff = 0.95 cfs @ 12.05 hrs, Volume= 0.064 af, Depth= 1.67" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10YR Rainfall=4.50" Area (sf) CN Description 19,957 70 1/2 acre lots, 25% imp, HSG B Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.9 Direct Entry, Calculated Subcatchment 31S: Barn area Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Type III 24-hr 10YR Rainfall=4.50" Runoff Area=19,957 sf Runoff Volume=0.064 af Runoff Depth=1.67" Tc=2.9 min CN=70 0.95 cfs Type III 24-hr 10YR Rainfall=4.50"30Will-Prop Page 59Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 32S: Roof Tops of Duplexes [46] Hint: Tc=0 (Instant runoff peak depends on dt) Runoff = 1.02 cfs @ 12.00 hrs, Volume= 0.072 af, Depth= 4.26" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10YR Rainfall=4.50" Area (sf) CN Description 3,101 98 roofs 3,101 98 roofs 1,324 98 roofs 1,324 98 roofs 8,850 98 Weighted Average Subcatchment 32S: Roof Tops of Duplexes Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Type III 24-hr 10YR Rainfall=4.50" Runoff Area=8,850 sf Runoff Volume=0.072 af Runoff Depth=4.26" Tc=0.0 min CN=98 1.02 cfs Type III 24-hr 10YR Rainfall=4.50"30Will-Prop Page 60Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 40S: Southern parcel side [46] Hint: Tc=0 (Instant runoff peak depends on dt) Runoff = 0.37 cfs @ 12.01 hrs, Volume= 0.026 af, Depth= 1.08" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10YR Rainfall=4.50" Area (sf) CN Description 12,681 61 >75% Grass cover, Good, HSG B Subcatchment 40S: Southern parcel side Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.4 0.38 0.36 0.34 0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Type III 24-hr 10YR Rainfall=4.50" Runoff Area=12,681 sf Runoff Volume=0.026 af Runoff Depth=1.08" Tc=0.0 min CN=61 0.37 cfs Type III 24-hr 10YR Rainfall=4.50"30Will-Prop Page 61Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Reach 9R: Existing 24" Drain [52] Hint: Inlet conditions not evaluated [79] Warning: Submerged Pond 12P Primary device # 1 INLET by 1.26' Inflow Area = 1.161 ac, Inflow Depth = 2.05" for 10YR event Inflow = 1.56 cfs @ 12.07 hrs, Volume= 0.199 af Outflow = 1.16 cfs @ 12.35 hrs, Volume= 0.197 af, Atten= 26%, Lag= 17.1 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs / 3 Max. Velocity= 0.6 fps, Min. Travel Time= 9.0 min Avg. Velocity = 0.2 fps, Avg. Travel Time= 22.2 min Peak Depth= 1.26' @ 12.20 hrs Capacity at bank full= 1.60 cfs Inlet Invert= 79.60', Outlet Invert= 79.58' 24.0" Diameter Pipe n= 0.015 Length= 300.0' Slope= 0.0001 '/' Reach 9R: Existing 24" Drain Inflow Outflow Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Inflow Area=1.161 ac Peak Depth=1.26' Max Vel=0.6 fps D=24.0" n=0.015 L=300.0' S=0.0001 '/' Capacity=1.60 cfs 1.56 cfs 1.16 cfs Type III 24-hr 10YR Rainfall=4.50"30Will-Prop Page 62Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Pond 11P: Duplexes Perimeter Subdrain for Rooftop Inflow Area = 0.203 ac, Inflow Depth = 4.26" for 10YR event Inflow = 1.02 cfs @ 12.00 hrs, Volume= 0.072 af Outflow = 0.19 cfs @ 12.40 hrs, Volume= 0.072 af, Atten= 81%, Lag= 24.0 min Primary = 0.17 cfs @ 12.40 hrs, Volume= 0.061 af Secondary = 0.02 cfs @ 11.55 hrs, Volume= 0.012 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 88.79' @ 12.40 hrs Surf.Area= 1,548 sf Storage= 799 cf Plug-Flow detention time= 26.1 min calculated for 0.072 af (100% of inflow) Center-of-Mass det. time= 25.9 min ( 770.2 - 744.3 ) # Invert Avail.Storage Storage Description 1 87.50' 1,858 cf Custom Stage Data (Prismatic) Listed below x 3 Elevation Surf.Area Voids Inc.Store Cum.Store (feet) (sq-ft) (%) (cubic-feet) (cubic-feet) 87.50 516 40.0 0 0 90.50 516 40.0 619 619 # Routing Invert Outlet Devices 1 Primary 87.00'4.0" x 100.0' long Culvert X 2.00 CMP, projecting, no headwall, Ke= 0.900 Outlet Invert= 86.00' S= 0.0100 '/' n= 0.013 Cc= 0.900 2 Device 1 87.00'0.4" Horiz. Orifice/Grate X 30.00 Limited to weir flow C= 0.600 3 Secondary 0.00'0.000830 fpm Exfiltration over entire Surface area Primary OutFlow Max=0.17 cfs @ 12.40 hrs HW=88.79' (Free Discharge) 1=Culvert (Passes 0.17 cfs of 0.56 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.17 cfs @ 6.4 fps) Secondary OutFlow Max=0.02 cfs @ 11.55 hrs HW=87.53' (Free Discharge) 3=Exfiltration (Exfiltration Controls 0.02 cfs) Type III 24-hr 10YR Rainfall=4.50"30Will-Prop Page 63Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Pond 11P: Duplexes Perimeter Subdrain for Rooftop Inflow Outflow Primary Secondary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Inflow Area=0.203 ac Peak Elev=88.79' Storage=799 cf 1.02 cfs 0.19 cfs 0.17 cfs 0.02 cfs Type III 24-hr 10YR Rainfall=4.50"30Will-Prop Page 64Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Pond 12P: Bio Retension Pond [79] Warning: Submerged Pond 11P Primary device # 1 INLET by 0.53' Inflow Area = 0.703 ac, Inflow Depth = 2.38" for 10YR event Inflow = 1.36 cfs @ 12.04 hrs, Volume= 0.140 af Outflow = 0.70 cfs @ 12.21 hrs, Volume= 0.140 af, Atten= 49%, Lag= 10.3 min Primary = 0.69 cfs @ 12.21 hrs, Volume= 0.135 af Secondary = 0.01 cfs @ 12.21 hrs, Volume= 0.005 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs / 2 Peak Elev= 87.53' @ 12.21 hrs Surf.Area= 495 sf Storage= 700 cf Plug-Flow detention time= 11.5 min calculated for 0.140 af (100% of inflow) Center-of-Mass det. time= 11.4 min ( 822.1 - 810.7 ) # Invert Avail.Storage Storage Description 1 85.00' 2,047 cf Custom Stage Data (Irregular) Listed below Elevation Surf.Area Perim. Voids Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (feet) (%) (cubic-feet) (cubic-feet) (sq-ft) 85.00 300 87.0 40.0 0 0 300 86.00 300 87.0 50.0 150 150 387 87.00 300 87.6 100.0 300 450 475 88.00 669 144.1 100.0 472 922 1,523 89.00 1,654 312.5 100.0 1,125 2,047 7,646 # Routing Invert Outlet Devices 1 Primary 79.60'24.0" x 300.0' long Culvert RCP, rounded edge headwall, Ke= 0.100 Outlet Invert= 79.58' S= 0.0001 '/' n= 0.015 Cc= 0.900 2 Secondary 0.00'0.000830 fpm Exfiltration over entire Surface area 3 Device 1 87.90'24.0" Horiz. Orifice/Grate Limited to weir flow C= 0.600 4 Device 1 85.00'0.4" Horiz. Perferatef subdrain X 50.00 Limited to weir flow C= 0.600 5 Device 1 86.65'4.0" Vert. Orifice/Grate C= 0.600 Primary OutFlow Max=0.69 cfs @ 12.21 hrs HW=87.53' (Free Discharge) 1=Culvert (Passes 0.69 cfs of 24.94 cfs potential flow) 3=Orifice/Grate ( Controls 0.00 cfs) 4=Perferatef subdrain (Orifice Controls 0.33 cfs @ 7.7 fps) 5=Orifice/Grate (Orifice Controls 0.35 cfs @ 4.1 fps) Secondary OutFlow Max=0.01 cfs @ 12.21 hrs HW=87.53' (Free Discharge) 2=Exfiltration (Exfiltration Controls 0.01 cfs) Type III 24-hr 10YR Rainfall=4.50"30Will-Prop Page 65Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Pond 12P: Bio Retension Pond Inflow Outflow Primary Secondary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Inflow Area=0.703 ac Peak Elev=87.53' Storage=700 cf 1.36 cfs 0.70 cfs 0.69 cfs 0.01 cfs Type III 24-hr 100YR Rainfall=6.50"30Will-Prop Page 66Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=3,387 sf Runoff Depth=3.71"Subcatchment 10S: Williams Frontage Tc=1.1 min CN=75 Runoff=0.37 cfs 0.024 af Runoff Area=2,367 sf Runoff Depth=2.08"Subcatchment 20S: Southern Neighbor Tc=2.2 min CN=58 Runoff=0.14 cfs 0.009 af Runoff Area=21,778 sf Runoff Depth=3.51"Subcatchment 30S: Main area Tc=2.0 min CN=73 Runoff=2.26 cfs 0.146 af Runoff Area=19,957 sf Runoff Depth=3.21"Subcatchment 31S: Barn area Tc=2.9 min CN=70 Runoff=1.88 cfs 0.122 af Runoff Area=8,850 sf Runoff Depth=6.26"Subcatchment 32S: Roof Tops of Duplexes Tc=0.0 min CN=98 Runoff=1.48 cfs 0.106 af Runoff Area=12,681 sf Runoff Depth=2.35"Subcatchment 40S: Southern parcel side Tc=0.0 min CN=61 Runoff=0.89 cfs 0.057 af Peak Depth=2.00' Max Vel=0.6 fps Inflow=3.97 cfs 0.353 afReach 9R: Existing 24" Drain D=24.0" n=0.015 L=300.0' S=0.0001 '/' Capacity=1.60 cfs Outflow=1.70 cfs 0.350 af Peak Elev=89.65' Storage=1,334 cf Inflow=1.48 cfs 0.106 afPond 11P: Duplexes Perimeter Subdrain for Primary=0.21 cfs 0.090 af Secondary=0.02 cfs 0.016 af Outflow=0.23 cfs 0.106 af Peak Elev=88.05' Storage=981 cf Inflow=2.43 cfs 0.236 afPond 12P: Bio Retension Pond Primary=2.05 cfs 0.230 af Secondary=0.01 cfs 0.006 af Outflow=2.06 cfs 0.236 af Total Runoff Area = 1.584 ac Runoff Volume = 0.465 af Average Runoff Depth = 3.52" Type III 24-hr 100YR Rainfall=6.50"30Will-Prop Page 67Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 10S: Williams Frontage [49] Hint: Tc<2dt may require smaller dt Runoff = 0.37 cfs @ 12.02 hrs, Volume= 0.024 af, Depth= 3.71" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100YR Rainfall=6.50" Area (sf) CN Description 3,387 75 1/4 acre lots, 38% imp, HSG B Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.1 Direct Entry, calculated Subcatchment 10S: Williams Frontage Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.4 0.38 0.36 0.34 0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Type III 24-hr 100YR Rainfall=6.50" Runoff Area=3,387 sf Runoff Volume=0.024 af Runoff Depth=3.71" Tc=1.1 min CN=75 0.37 cfs Type III 24-hr 100YR Rainfall=6.50"30Will-Prop Page 68Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 20S: Southern Neighbor [49] Hint: Tc<2dt may require smaller dt Runoff = 0.14 cfs @ 12.05 hrs, Volume= 0.009 af, Depth= 2.08" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100YR Rainfall=6.50" Area (sf) CN Description 2,367 58 Woods/grass comb., Good, HSG B Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.2 Direct Entry, Calculated Subcatchment 20S: Southern Neighbor Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.15 0.14 0.13 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Type III 24-hr 100YR Rainfall=6.50" Runoff Area=2,367 sf Runoff Volume=0.009 af Runoff Depth=2.08" Tc=2.2 min CN=58 0.14 cfs Type III 24-hr 100YR Rainfall=6.50"30Will-Prop Page 69Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 30S: Main area [49] Hint: Tc<2dt may require smaller dt Runoff = 2.26 cfs @ 12.04 hrs, Volume= 0.146 af, Depth= 3.51" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100YR Rainfall=6.50" Area (sf) CN Description 14,928 61 >75% Grass cover, Good, HSG B 4,495 98 Paved roofs 2,355 98 Driveways 21,778 73 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.0 Direct Entry, Subcatchment 30S: Main area Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)2 1 0 Type III 24-hr 100YR Rainfall=6.50" Runoff Area=21,778 sf Runoff Volume=0.146 af Runoff Depth=3.51" Tc=2.0 min CN=73 2.26 cfs Type III 24-hr 100YR Rainfall=6.50"30Will-Prop Page 70Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 31S: Barn area [49] Hint: Tc<2dt may require smaller dt Runoff = 1.88 cfs @ 12.05 hrs, Volume= 0.122 af, Depth= 3.21" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100YR Rainfall=6.50" Area (sf) CN Description 19,957 70 1/2 acre lots, 25% imp, HSG B Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.9 Direct Entry, Calculated Subcatchment 31S: Barn area Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)2 1 0 Type III 24-hr 100YR Rainfall=6.50" Runoff Area=19,957 sf Runoff Volume=0.122 af Runoff Depth=3.21" Tc=2.9 min CN=70 1.88 cfs Type III 24-hr 100YR Rainfall=6.50"30Will-Prop Page 71Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 32S: Roof Tops of Duplexes [46] Hint: Tc=0 (Instant runoff peak depends on dt) Runoff = 1.48 cfs @ 12.00 hrs, Volume= 0.106 af, Depth= 6.26" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100YR Rainfall=6.50" Area (sf) CN Description 3,101 98 roofs 3,101 98 roofs 1,324 98 roofs 1,324 98 roofs 8,850 98 Weighted Average Subcatchment 32S: Roof Tops of Duplexes Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Type III 24-hr 100YR Rainfall=6.50" Runoff Area=8,850 sf Runoff Volume=0.106 af Runoff Depth=6.26" Tc=0.0 min CN=98 1.48 cfs Type III 24-hr 100YR Rainfall=6.50"30Will-Prop Page 72Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Subcatchment 40S: Southern parcel side [46] Hint: Tc=0 (Instant runoff peak depends on dt) Runoff = 0.89 cfs @ 12.01 hrs, Volume= 0.057 af, Depth= 2.35" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100YR Rainfall=6.50" Area (sf) CN Description 12,681 61 >75% Grass cover, Good, HSG B Subcatchment 40S: Southern parcel side Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.95 0.9 0.85 0.8 0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Type III 24-hr 100YR Rainfall=6.50" Runoff Area=12,681 sf Runoff Volume=0.057 af Runoff Depth=2.35" Tc=0.0 min CN=61 0.89 cfs Type III 24-hr 100YR Rainfall=6.50"30Will-Prop Page 73Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Reach 9R: Existing 24" Drain [52] Hint: Inlet conditions not evaluated [55] Hint: Peak inflow is 248% of Manning's capacity [76] Warning: Detained 0.021 af (Pond w/culvert advised) [79] Warning: Submerged Pond 12P Primary device # 1 INLET by 2.00' Inflow Area = 1.161 ac, Inflow Depth = 3.64" for 100YR event Inflow = 3.97 cfs @ 12.07 hrs, Volume= 0.353 af Outflow = 1.70 cfs @ 12.94 hrs, Volume= 0.350 af, Atten= 57%, Lag= 52.3 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs / 3 Max. Velocity= 0.6 fps, Min. Travel Time= 8.6 min Avg. Velocity = 0.3 fps, Avg. Travel Time= 19.1 min Peak Depth= 2.00' @ 12.05 hrs Capacity at bank full= 1.60 cfs Inlet Invert= 79.60', Outlet Invert= 79.58' 24.0" Diameter Pipe n= 0.015 Length= 300.0' Slope= 0.0001 '/' Reach 9R: Existing 24" Drain Inflow Outflow Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)4 3 2 1 0 Inflow Area=1.161 ac Peak Depth=2.00' Max Vel=0.6 fps D=24.0" n=0.015 L=300.0' S=0.0001 '/' Capacity=1.60 cfs 3.97 cfs 1.70 cfs Type III 24-hr 100YR Rainfall=6.50"30Will-Prop Page 74Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Pond 11P: Duplexes Perimeter Subdrain for Rooftop Inflow Area = 0.203 ac, Inflow Depth = 6.26" for 100YR event Inflow = 1.48 cfs @ 12.00 hrs, Volume= 0.106 af Outflow = 0.23 cfs @ 12.44 hrs, Volume= 0.106 af, Atten= 85%, Lag= 26.5 min Primary = 0.21 cfs @ 12.44 hrs, Volume= 0.090 af Secondary = 0.02 cfs @ 11.20 hrs, Volume= 0.016 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 89.65' @ 12.44 hrs Surf.Area= 1,548 sf Storage= 1,334 cf Plug-Flow detention time= 40.0 min calculated for 0.106 af (100% of inflow) Center-of-Mass det. time= 39.8 min ( 778.2 - 738.4 ) # Invert Avail.Storage Storage Description 1 87.50' 1,858 cf Custom Stage Data (Prismatic) Listed below x 3 Elevation Surf.Area Voids Inc.Store Cum.Store (feet) (sq-ft) (%) (cubic-feet) (cubic-feet) 87.50 516 40.0 0 0 90.50 516 40.0 619 619 # Routing Invert Outlet Devices 1 Primary 87.00'4.0" x 100.0' long Culvert X 2.00 CMP, projecting, no headwall, Ke= 0.900 Outlet Invert= 86.00' S= 0.0100 '/' n= 0.013 Cc= 0.900 2 Device 1 87.00'0.4" Horiz. Orifice/Grate X 30.00 Limited to weir flow C= 0.600 3 Secondary 0.00'0.000830 fpm Exfiltration over entire Surface area Primary OutFlow Max=0.21 cfs @ 12.44 hrs HW=89.65' (Free Discharge) 1=Culvert (Passes 0.21 cfs of 0.65 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.21 cfs @ 7.8 fps) Secondary OutFlow Max=0.02 cfs @ 11.20 hrs HW=87.53' (Free Discharge) 3=Exfiltration (Exfiltration Controls 0.02 cfs) Type III 24-hr 100YR Rainfall=6.50"30Will-Prop Page 75Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Pond 11P: Duplexes Perimeter Subdrain for Rooftop Inflow Outflow Primary Secondary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Inflow Area=0.203 ac Peak Elev=89.65' Storage=1,334 cf 1.48 cfs 0.23 cfs 0.21 cfs 0.02 cfs Type III 24-hr 100YR Rainfall=6.50"30Will-Prop Page 76Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Pond 12P: Bio Retension Pond [79] Warning: Submerged Pond 11P Primary device # 1 INLET by 1.05' Inflow Area = 0.703 ac, Inflow Depth = 4.04" for 100YR event Inflow = 2.43 cfs @ 12.04 hrs, Volume= 0.236 af Outflow = 2.06 cfs @ 12.08 hrs, Volume= 0.236 af, Atten= 15%, Lag= 2.2 min Primary = 2.05 cfs @ 12.08 hrs, Volume= 0.230 af Secondary = 0.01 cfs @ 12.08 hrs, Volume= 0.006 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs / 2 Peak Elev= 88.05' @ 12.08 hrs Surf.Area= 720 sf Storage= 981 cf Plug-Flow detention time= (not calculated: outflow precedes inflow) Center-of-Mass det. time= (not calculated) # Invert Avail.Storage Storage Description 1 85.00' 2,047 cf Custom Stage Data (Irregular) Listed below Elevation Surf.Area Perim. Voids Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (feet) (%) (cubic-feet) (cubic-feet) (sq-ft) 85.00 300 87.0 40.0 0 0 300 86.00 300 87.0 50.0 150 150 387 87.00 300 87.6 100.0 300 450 475 88.00 669 144.1 100.0 472 922 1,523 89.00 1,654 312.5 100.0 1,125 2,047 7,646 # Routing Invert Outlet Devices 1 Primary 79.60'24.0" x 300.0' long Culvert RCP, rounded edge headwall, Ke= 0.100 Outlet Invert= 79.58' S= 0.0001 '/' n= 0.015 Cc= 0.900 2 Secondary 0.00'0.000830 fpm Exfiltration over entire Surface area 3 Device 1 87.90'24.0" Horiz. Orifice/Grate Limited to weir flow C= 0.600 4 Device 1 85.00'0.4" Horiz. Perferatef subdrain X 50.00 Limited to weir flow C= 0.600 5 Device 1 86.65'4.0" Vert. Orifice/Grate C= 0.600 Primary OutFlow Max=1.99 cfs @ 12.08 hrs HW=88.05' (Free Discharge) 1=Culvert (Passes 1.99 cfs of 26.01 cfs potential flow) 3=Orifice/Grate (Weir Controls 1.16 cfs @ 1.3 fps) 4=Perferatef subdrain (Orifice Controls 0.37 cfs @ 8.4 fps) 5=Orifice/Grate (Orifice Controls 0.47 cfs @ 5.3 fps) Secondary OutFlow Max=0.01 cfs @ 12.08 hrs HW=88.05' (Free Discharge) 2=Exfiltration (Exfiltration Controls 0.01 cfs) Type III 24-hr 100YR Rainfall=6.50"30Will-Prop Page 77Prepared by Sharff Group, LTD 24/06/2020HydroCAD® 7.00 s/n 000905 © 1986-2003 Applied Microcomputer Systems Pond 12P: Bio Retension Pond Inflow Outflow Primary Secondary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)2 1 0 Inflow Area=0.703 ac Peak Elev=88.05' Storage=981 cf 2.43 cfs 2.06 cfs 2.05 cfs 0.01 cfs