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_2022-12-15 CoHousing SWM Closeout 4 Allen Place, Northampton, MA 01060 (413) 582-7000 bdg@berkshiredesign.com Berkshire Design Group December 15, 2022 Doug McDonald Northampton DPW RE: Village Hill Co-Housing Stormwater Record Plans, Closeout, and Certification Dear Doug: The purpose of this letter is to provide the required as-built information and the closeout documentation for the stormwater management system for the Co-Housing project located northeast of the northerly terminus of Olander Drive (Map 31C, Lot 81) in Northampton. The project, which is part of the larger Village Hill development, was approved for a Northampton Stormwater Permit, issued 8/9/2018 (attached). Construction of the project has been completed, and all areas disturbed by construction have been permanently stabilized. Record plans for the constructed project are enclosed with this letter. The plans consist of four sheets, titled Village Hill – Northampton, MA – Cohousing (12/13/2022) and are marked “Record Plan”. The plan set is based on a compilation of contractor’s “redline” markups, observation by Berkshire Design Group, and limited land surveying measurements. Sheet R.1 and R.2 include a note specifically identifying which portions of the plan have been surveyed. Remaining items have been shown based on contractor “redline” plans and observation by Berkshire Design. Only building footprints, and those components of the stormwater system with elevations critical to the function of the system have been surveyed. Impervious Cover/Drainage Area Delineation In reviewing the as-built condition of the site, Berkshire Design observed the following discrepancies with the approved plans. As-built impervious cover within the Co-Housing property varies slightly from the areas shown in the approved plans. However, the approved plans included an assumption of an additional 10% impervious area to account for future increases. For this reason, the as-built condition of the project reflects 0.222 acres less impervious area than is accounted for in the approved stormwater modeling. Yard Drain YD6, located in the northwest corner of the site was connected to the stormwater discharge flowing offsite to the north. The approved plans called for this drain to discharge to the storm drain system in the interior of the site, in order to be routed to Detention Basin #2 east of the Co-Housing property. This resulted in a larger drainage area and slightly more impervious area (primarily roof area) discharging directly offsite. Berkshire Design has prepared the attached As-Built Drainage Area Plan, labeled as Figure A, which shows the as-built drainage area delineations and impervious cover for the watershed draining to a control point north of the site, which includes the entire Co-Housing property. As discussed below, the impact to the design stormwater model has been analyzed based on these drainage areas and groundcovers. Attached record plans include a note stating that an additional 0.222 acres of impervious area may be constructed, subject to DPW review, and stating that any such areas must be routed to Detention Basin #2. Detention Basin As-Built Condition Prior to construction, a topographic survey of Detention Basin #2 (round basin east of the cohousing site) and December 15, 2022 Village Hill Co-Housing Stormwater As-Built Certification Page 2 of 6 4 Allen Place, Northampton, MA 01060 (413) 582-7000 bdg@berkshiredesign.com Detention Basin #4 (serpentine basin south of the cohousing site) was completed by Sherman & Frydryk, LLC and shown on a plan dated 5/11/2018. Storage volume for both basins was modeled during design based on this plan. Based on that survey, it was determined that the detention basins had been constructed smaller than was intended in the original design for the Village Hill development. The design for Co-Housing proposed modifications of the outlet controls (concrete weir structures and emergency spillways) to control post- construction runoff to a level below the pre-development condition. No modifications to the storage volume of the basins were proposed. During construction of the Co-Housing project, the outlet control features were modified, and the as-built condition was surveyed by Berkshire Design Group. The detention basins are located on land belonging to the Village Hill homeowner’s association (“Village at Hospital Hill North Association”) as common land. Berkshire Design has prepared the attached record plan for the detention basins and surrounding drainage features within the common property. As-Built Stormwater Model The approved HydroCAD stormwater model for the project was updated to reflect the as-built condition. Impervious areas were revised and are inclusive of the un-built 0.222 acres of future impervious area (note that any future impervious area must be routed to Detention Basin #2). Elevations for detention basin control structures modified during construction were modeled using surveyed as-built elevations. The as-built HydroCAD model is attached. The intention of the approved design was to provide for a reduction in peak flow rates verses the pre-development condition, while minimizing or eliminating use of the emergency overflow spillway on the basins under all design storms. The as-built HydroCAD model is attached. Discharges to the control point north of the site, which receives all runoff from the co-housing property are summarized in the table below, which shows the pre- and post- development runoff conditions as stated in the approved stormwater report and compares them to the modeled runoff for the as-built condition. Condition & Point of Analysis 2-Year Storm 3.00” 10-Year Storm 4.50” 25-Year Storm 2.25” 100-Year Storm 7.00” Peak Flow Rate(cfs) Peak Flow Rate(cfs) Peak Flow Rate(cfs) Peak Flow Rate(cfs) Pre-Development to Northeast Control Point (DP-2)* 20.50 46.04 59.97 93.89 Post-Development to Northeast Control Point (DP-2)* As-Designed 13.35 32.71 48.26 82.87 Post-Development to Northeast Control Point (DP-2)* As-Built 13.68 31.65 47.67 85.48 *Names in parentheses refer to HydroCad model and calculations. The discharge over the emergency spillway in each basin was also modeled as a secondary design goal, based on the conditions reflected in the approved stormwater management report and the as-built condition. December 15, 2022 Village Hill Co-Housing Stormwater As-Built Certification Page 3 of 6 4 Allen Place, Northampton, MA 01060 (413) 582-7000 bdg@berkshiredesign.com Condition & Point of Analysis 2-Year Storm 3.00” 10-Year Storm 4.50” 25-Year Storm 2.25” 100-Year Storm 7.00” Peak Flow Rate(cfs) Peak Flow Rate(cfs) Peak Flow Rate(cfs) Peak Flow Rate(cfs) Spillway Discharge Basin #2 (P2)* As-Designed 0.00 0.00 0.00 0.00 Spillway Discharge Basin #2 (P2)* As-Built 0.00 0.00 0.00 0.53 Spillway Discharge Basin #4 (P4)* As-Designed 0.00 0.00 0.00 0.00 Spillway Discharge Basin #4 (P4)* As-Built 0.00 0.00 0.00 0.09 *Names in parentheses refer to HydroCad model and calculations. Water Quality Swales The approved design included detailing for water quality swales at several locations within the interior of the site. The swales were included in order to incorporate low-impact design (LID) components into the project by encouraging filtering and infiltration of runoff and slowing the runoff time in a decentralized manner. However, the swales were not accounted for in the approved stormwater calculations for either water quantity or water quality. During construction, grades were raised around the water quality swales such that the rims of overflow yard drains were even with finished grade in order to aid in the management of water during temporary construction conditions (verses rim elevations 2 inches higher than surrounding grade in the approved design). At the time of Berkshire Design’s last site visit in November 2022, all yard drains within water quality swales were set at least 2 inches higher than surrounding grade. Sediment on Pavement & Catch Basins Construction of the co-housing project was completed in spring 2022. Subsequently, construction-related sediment was observed near and within pavement areas. In August 2022, Dietz Construction, the site contractor, cleaned sediment from the drainage structures. An invoice for the work is attached to this letter. Permit Conditions At this time, all conditions of the stormwater permit have been satisfied. Status of conditions is listed below. Refer to the attached stormwater permit (8/9/2018) for specific condition language Standard Conditions 1. Conformance with Plans – Except as described above, the project was built in substantial conformance with the documents referenced in the permit. December 15, 2022 Village Hill Co-Housing Stormwater As-Built Certification Page 4 of 6 4 Allen Place, Northampton, MA 01060 (413) 582-7000 bdg@berkshiredesign.com 2. DPW Inspections – The developer and contractor arranged for inspections at appropriate times. 3. Project Engineer – Christopher Chamberland (MA PE 51074) was the project engineer during construction. Record plans and a certification statement are attached to this letter. 4. Annual Reports – Noted 5. Construction Start within Five Years – Construction is now completed. Specific Conditions 1. Operation & Maintenance Agreement – An agreement was signed and recorded at the Registry of Deeds on 2/22/2019. 2. EPA NOI – A Stormwater Pollution Prevention Plan (SWPPP) was prepared and an EPA NOI was filed on 9/13/2018. 3. Protection During Construction – Drainage components were protected during construction. During a site visit by Berkshire Design in November 2022, water quality swales appeared to be fully functional without standing water or saturated soils. 4. Revised Construction Plans – Final construction plans, inclusive of DPW comments, dated 9/25/2018 were submitted prior to construction. 5. Detention Basin Record Plan – The record plan has been prepared and is attached to this letter. 6. Impervious Areas – Noted for future development. As described above, the approved design allows for an additional 0.222 acres of impervious area to be constructed within the interior of the Co-Housing project, contingent on runoff from the new areas being routed to Detention Basin #2. This information has been included on the record plans for the benefit of DPW and future property owners. 7. Requirement to Reduce Peak Flows – Noted. DPW Post-Construction Comments Berkshire Design is in receipt of your comments, which were sent by email on 11/10/2022. The comments summarized items required for project closeout, and are addressed below. 1. DPW: The as-built plans should include a certification statement from an engineer as described in Standard Permit Condition #3 in the attached Stormwater Permit. BDG: A certification statement is included as an attachment to this letter. 2. DPW: Inverts of drainage structures have been included in the Record Plan however only some of the elevations appear to be based on surveyed as-built conditions. The plans should clarify what elevations have been surveyed and the Project Engineer must describe how the design elevations were confirmed if they were not surveyed. BDG: A note has been added to record plans to clearly indicate which existing conditions are based on survey and which are based on contractor redline/BDG observation. See further discussion above. 3. DPW: The impervious areas in the Record Plan do not represent the as-built conditions or the approved plans. For example the portions of the paved pathways were constructed with approximately 15 foot paved widths which differs from the approved plans that specified 6 foot wide paved paths with the December 15, 2022 Village Hill Co-Housing Stormwater As-Built Certification Page 5 of 6 4 Allen Place, Northampton, MA 01060 (413) 582-7000 bdg@berkshiredesign.com addition of "Reinforced Mat for Emergency Access" in certain areas. It appears the reinforced turf pavers were not constructed and the pathway width was increased in some areas. The Record Plans should represent the as-built conditions of all surface types including all impervious surfaces. If the project has been constructed with an increase to the impervious area that was specified in the approved plans and documents, the Project Engineer should submit to the DPW for review revised drainage calculations representing the as-built conditions and confirmation that the project is in compliance with the stormwater standards. BDG: Record plans have been updated, and an as-built drainage area plan has been attached to this letter. As discussed above, the HydroCAD model for the project has been updated and the discrepancies have not significantly affected the stormwater design. The property still has capacity for additional impervious area based on design and this has been noted on the drainage area plan and record drawings. 4. DPW: During inspection of the site by the DPW on 11/9/21, sediment was observed in paved areas and at least one catch basin contained a silt sack or similar device. All stormwater structures and paved areas should be inspected and cleaned of construction sediment and debris including but limited to the parking lots, treatment chamber and catch basins. Proof that the paved area and structures are clean must be provided to the DPW in the form of receipts and inspection reports from the Project Engineer. BDG: As noted above, the site contractor corrected these issues and receipt of service is attached. During a site visit in November pavement appeared to be clean of sediment. 5. DPW: The Flared End Outlet FE7 was not constructed with a level lip spreader as shown in the Record Plans and approved plans. BDG: Outlet FE7 has been corrected. 6. DPW: Drain manhole 24 was not visible as specified in the Record Plans. Please confirm the status of this manhole. BDG: DMH 24 was inadvertently covered during final paving. The rim and cover have been raised to be flush with grade. 7. DPW: Yard Drain YD14 and the water quality swale was not visible and may not have been constructed as shown in the Record Plans. BDG: Modifications to the architectural details of the adjacent structure allowed the exterior grade to be raised slightly, thus eliminating the need for the additional yard drain. Yard Drain YD 14 was eliminated; however, Yard Drain YD16 was converted from a standard yard drain to a water quality swale and now captures a similar area. December 15, 2022 Village Hill Co-Housing Stormwater As-Built Certification Page 6 of 6 4 Allen Place, Northampton, MA 01060 (413) 582-7000 bdg@berkshiredesign.com 8. DPW: The make and model of the installed Treatment Chamber should be specified in the Record Plans. BDG: Make and model have been indicated on the callout for the treatment chamber. Cut sheet is attached for reference. 9. DPW: The riprap apron below Flared End Outlet FE31 has partially slid down the slope and fabric is visible. Additional larger riprap or other measures should be completed as necessary to stabilize the slope of the detention basin below FE31. BDG: Additional riprap was added during the summer to the outlet to correct the issue. As of the date of this letter, riprap appears to be holding well in this location and additional modification does not appear to be necessary. 10. DPW: Detail 3 / L.19 Water Quality Swale Underdrain in the approved plans included the note: "The rim of all yard drains within water quality swales shall be set a minimum of 2" higher than adjacent grade." It appears that the yard drains within water quality swales were not constructed consistently to this specification. BDG: The elevation around the yard drains have been modified to ensure rim elevations are a minimum of 2” higher than adjacent grade. 11. DPW: the Stormwater Management Permit included Specific Permit Condition 5 that requires that a revised, surveyed Record Plan of Detention Basin 2 and 4 be submitted to the DPW for review and approval. This Record Plan is separate from the Cohousing Record Plan and should be submitted at this time. BDG: Berkshire Design prepared the requested record plan and it is attached to this letter. We believe that this letter and the attached documents complete all closeout requirements for the above- referenced stormwater permit. Please contact us if you have any further questions or comments. Sincerely, Berkshire Design Group Christopher Chamberland, P.E. Principal 4 Allen Place, Northampton, MA 01060 (413) 582-7000 bdg@berkshiredesign.com Berkshire Design Group December 14, 2022 Doug McDonald Stormwater Manager Northampton Department of Public Works RE: Village Hill Co-Housing Stormwater Management System Certification Dear Doug: Sunwood Builders was issued a stormwater permit for the Village Hill Co-Housing project on Olander Drive (Map 31C, Lot 81) on 8/9/2018. Berkshire Design is the engineer of record for the above-referenced project. Personnel from Berkshire Design were on site during critical periods to observe the materials and construction of the stormwater management facilities. Additionally, as-built conditions of certain critical components of the stormwater system were surveyed by Berkshire Design after completion. The project was built in general conformance with the approved plans; however, we have noted discrepancies between the design plans and the as-built condition. We have analyzed these changes for potential impact to the design goals established prior to project approval. The changes and our analysis are summarized in a separate letter to you, dated 12/13/2022 Based upon the information listed above, it is my professional opinion that the stormwater facilities will function as designed. Sincerely, Berkshire Design Group Christopher Chamberland, P.E. Principal Bituminous Concrete Bituminous Concrete Bituminous Conc r e t e Bituminou s C o n c r e t e Bitum inous Conc reteGrave l Grave l Grave lGravel Bituminou s C o n c r et e Lawn Law n LawnGravel Gravel Gravel Meadow Meadow Lawn Meadow Meadow Meadow Meadow Mead o w Mea d ow Meadow Meadow Meadow drainage channelDDDDD IN FAVOR OF HOSPITALHILL DEVELOPMENT LLC CONSERVATION EASEMENT A62,549 SQ.FT.OR 1.435 ACRES (SEE NOTE #9) IN FAVOR OF HOSPITALHILL DEVELOPMENT LLC 84,663 SQ.FT.OR 1.943 ACRES DRAINAGE EASEMENT E Bike Path Easement D 6' Pedestrian Easement Plan Book 216, Page 71 Drainage Easement 10' Bike Path EasementPlan Book 216, Page 7112' P e d e s t r i an E a s em e n t P l a n B o o k 2 1 6 , P a g e 7 1 Drainage Easement FPlan Book 216, Page 71 Easement Area E21Plan Book 216, Page 71Easement Area E27Sewer EasementDeed Book 9341, Page 327Plan Book 217, Page 33 Intermitt e n t S t r e a m (Federal J u r i s d i c t i o n ) X WATERELEV=136.6'(11/17/2003) Lot 13-A CenterOfRive rRiverMill Sewer EasementDeed Book 9341, Page 327Plan Book 217, Page 33 Drainage Easement Ac ce s s E a s e m e n t G Pla n B o o k 2 1 6 , P a g e 7 1Easement Area E21-A41.0 Acres1784204.8 Sq. Feet ± Ap pr o x ima t e S h or e L ine Mil l R i v e r D D DD D Ford Cro s si n g Ola nd e r D r iv e231231232232 232 231 231 231 232 233234229228 216 217 218 219221222223224226 227 228 229 231232 233 234 236 237 238 239 239238 237 236 234 233 232 232233234 236 237 232231229 226227228 223 22122222 4 218 217 219 216 231 227226228 221223222224 216219217218 211212 213214 206207208209 201202203204 196197198199 193 194 192 193 191 198199 201203204202 203 202 201 204207206208209 228 227 229 226222223221 224 216 219 217218214 211 212 213 226229 227228 224 221222223 216 212213214 211 209 208 207 206 201202203204199 199 197198 196 230 230 230 225 220 215 210 205 200230 230 230 235230 235 240 235 235 230 230 225 220 215 225220230 225 220 215 210210 205 205200 225 220 215 210 205 200 195 190 185180175170165 160155150145 200 195 190 200 205 210 215 220 225 230 190 185 175 180 185190 195 205 210 220215210 205 215210 206 207 208 209 211 212 201202 204 203 209 208207 206 212211213210 205 200 195210 205 215 D200200200200210 206200200200200 200200190192194196196198 196198198190190190200 192192190 200140150160170180204202 204202204206200 198 188194190190200 192194196 198202 https://www.mountainproject.com/photo/105857941 E231 231 204204 203.40203.57 203.36203.56 201.90 202.06 202.42 202.53 192 191.27191.47191.32191.43 191.87 191.55 191.95 191.79 //// / //220 215 206 225230210 206 208 205 203 214 217 211 212 213 204 210 211212 210 206 205 211 210 210 200 207 199 205 199 203 204200 197 203 197 204 204 204 196206 207 205 210 205 212 211 210 205 203200 204 204 201 202 203 203 211 192.12 192.24 203 204 200 210 VH-1 VH-7 VH-2 VH-8 VH-4 VH-3 VH-5 VH-6 230 231 229 231231 231 229 224 230 227 228228 228 228 229 230 230 230229 229 228 232234236238 229 229228227226.5 229 227 226 227 229 230230 229 204204 192D D D DD DD D D WVWVW W S S EEET T TTTTE E DDDDD DD D D DDP-2 HSG C HSG A WATER SURFACE WOODS IMPERVIOUS 1/8 ACRE RESIDENTIAL LOTS PDA-2A PAVEMENT & ROOF* 0.400 AC WOODS (HSG C) 2.344 AC GRASS (HSG C) 3.840 AC TOTAL IMPERVIOUS:0.400 AC TOTAL AREA: 6.584 AC *INCLUDES GRAVEL WALKING TRAIL PDA-2C PAVEMENT & ROOF*7.328 AC WATER SURFACE**0.785 AC 10% EXTRA IMPERVIOUS***0.733 AC GRASS (HSG B) 1.298 AC GRASS (HSG C) 5.591 AC TOTAL IMPERVIOUS: 8.846 AC TOTAL AREA: 15.735 AC *FROM GALE ASSOCIATES REPORT, INCLUSIVE OF PROPOSED TCB "LOT 20" PROJECT, BUT EXCLUDING 9,092 SQUARE FEET OF IMPERVIOUS AREA ALLOCATED TO THE MEADOW RUN PROJECT NORTH OF FORD CROSSING, AND INCLUDING 0.030 ACRES OF PROPOSED IMPERVIOUS AREA ON THE MEADOW RUN LOT AS SHOWN ON THIS SHEET **INCLUSIVE OF PROPOSED RAIN GARDEN AT TCB "LOT 20" PROJECT ON VILLAGE HILL RD ***ADDITIONAL 10% IMPERVIOUS AREA FACTOR OF SAFETY APPLIED TO ALL PAVEMENT & ROOF; SEE DISCUSSION IN CO-HOUSING DRAINAGE REPORT (7/23/2018) HSG A HSG B HSG C HSG C PDA-2D PAVEMENT & ROOF*1.824 AC WATER SURFACE 0.171 AC GRASS (HSG B) 1.139 AC WOODS (HSG C)0.410 AC GRASS (HSG C) 4.335 AC TOTAL IMPERVIOUS: 1.995 AC TOTAL AREA: 7.879 AC *SEE NOTE 3 HSG C HSG B PDA-2B PAVEMENT & ROOF 1.682 AC WATER SURFACE 0.068 AC GRASS (HSG B) 0.028 AC GRASS (HSG C) 2.111 AC TOTAL IMPERVIOUS: 1.750 AC TOTAL AREA: 3.889 AC PDA-2A PDA-2C PDA-2B PDA-2D Drawn By: Revisions Scale: Date:Sheet Number This drawing is not intended nor shall it be used for construction purposes unless the signed professional seal of a registered landscape architect, civil engineer or land surveyor employed by The Berkshire Design Group, Inc. is affixed above. Do not scale drawing for quantity take-offs or construction. Use written dimensions only. If dimensions are incomplete, contact The Berkshire Design Group Inc. for clarification. Copyright The Berkshire Design Group, Inc. This drawing and all of its contents are the express property of The Berkshire Design Group, Inc., and shall not be copied or used in any way without the written consent of The BerkshireDesign Group, Inc. c VILLAGE HILL CO-HOUSING SUNWOOD BUILDERS Web: http://www.berkshiredesign.com Email: bdg@berkshiredesign.com (413) 582-7000 4 Allen Place, Northampton, Massachusetts 01060 FAX (413) 582-7005 Landscape Architecture Civil Engineering Planning Berkshire Group Design Land Surveying FIG A DECEMBER 13, 2022 1"=250' CMC AS-BUILT DRAINAGE AREAS NOTES 1.RUNOFF FROM THE ENTIRE SITE OF THE CO-HOUSING PROJECT IS DIRECTED TO CONTROL POINT DP-2. DRAINAGE AREAS FOR OTHER CONTROL POINTS ARE OMITTED. 2.IMPERVIOUS AREAS WITHIN AREA 2C ARE BASED ON A TABULATION PUBLISHED BY GALE ASSOCIATES, DATED 1/5/2018. ALL OTHER GROUNDCOVERS ARE ESTIMATED BASED ON THE MEASUREMENTS SHOWN ON THIS PLAN. 3.THE APPROVED PLANS FOR THE COHOUSING PROJECT INCLUDED A TOTAL OF 2.224 ACRES OF PAVEMENT AND ROOF IMPERVIOUS AREA (INCLUSIVE OF IMPERVIOUS COVER WITHIN DRAINAGE AREAS PDA-2A AND PDA-2C. ACTUAL AS-BUILT CONDITION INCLUDES 2.002 ACRES OF PAVEMENT AND ROOF IMPERVIOUS AREA. THIS PLAN INCLUDES THE REMAINING, UN-BUILT 0.222 ACRES WITHIN PDA-2C, TO ACCOUNT FOR FUTURE CONSTRUCTION OF IMPERVIOUS SURFACES. PDA-2A Northern & Eastern Edges of Site PDA-2B TCB "Lot 13A" Project PDA-2C Southeast Corner of Site PDA-2D Future Co-Housing Site DP-2 Control Point for proposed drainage S1 Drainage Swale (Upper Segment) S2 Drainage Swale (Middle Segment) S3 Drainage Swale (Lower Segment) P2 Basin #2 (Survey) P4 Basin #4 (Survey) Routing Diagram for 17-058-Village Hill Co-Housing_As Built 2022-12-13 Prepared by Berkshire Design Group, Printed 12/15/2022 HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Subcat Reach Pond Link 17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 2HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Area Listing (selected nodes) Area (acres) CN Description (subcatchment-numbers) 2.465 61 >75% Grass cover, Good, HSG B (PDA-2B, PDA-2C, PDA-2D) 15.877 74 >75% Grass cover, Good, HSG C (PDA-2A, PDA-2B, PDA-2C, PDA-2D) 0.171 98 Detention Basin (PDA-2D) 0.785 98 Detention Pond/Rain Garden (PDA-2C) 7.328 98 Paved parking & roofs (PDA-2C) 0.733 98 Paved parking & roofs (10% Extra) (PDA-2C) 3.906 98 Pavement & Roof (PDA-2A, PDA-2B, PDA-2D) 0.068 98 Pond/Rain Garden (PDA-2B) 2.754 70 Woods, Good, HSG C (PDA-2A, PDA-2D) 34.087 82 TOTAL AREA Type III 24-hr 2-yr Rainfall=3.00"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 3HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=6.584 ac 6.08% Impervious Runoff Depth>0.91"Subcatchment PDA-2A: Northern & Eastern Tc=5.0 min CN=74 Runoff=6.60 cfs 0.498 af Runoff Area=3.889 ac 45.00% Impervious Runoff Depth>1.59"Subcatchment PDA-2B: TCB "Lot 13A" Tc=5.0 min CN=85 Runoff=7.25 cfs 0.514 af Runoff Area=15.735 ac 56.22% Impervious Runoff Depth>1.66"Subcatchment PDA-2C: Southeast Corner Tc=5.0 min CN=86 Runoff=30.69 cfs 2.178 af Runoff Area=7.879 ac 25.32% Impervious Runoff Depth>1.13"Subcatchment PDA-2D: Future Co-Housing Tc=5.0 min CN=78 Runoff=10.18 cfs 0.741 af Inflow=13.68 cfs 3.749 afReach DP-2: Control Point for proposed drainage Outflow=13.68 cfs 3.749 af Avg. Flow Depth=0.00' Max Vel=0.00 fps Inflow=0.00 cfs 0.000 afReach S1: Drainage Swale (Upper n=0.030 L=85.0' S=0.0141 '/' Capacity=62.64 cfs Outflow=0.00 cfs 0.000 af Avg. Flow Depth=0.38' Max Vel=2.61 fps Inflow=4.63 cfs 2.056 afReach S2: Drainage Swale (Middle n=0.030 L=235.0' S=0.0155 '/' Capacity=852.09 cfs Outflow=4.63 cfs 2.053 af Avg. Flow Depth=0.23' Max Vel=2.09 fps Inflow=4.63 cfs 2.053 afReach S3: Drainage Swale (Lower n=0.030 L=235.0' S=0.0155 '/' Capacity=71.42 cfs Outflow=4.63 cfs 2.049 af Peak Elev=188.26' Storage=18,966 cf Inflow=19.97 cfs 3.304 afPond P2: Basin #2 (Survey) Primary=9.19 cfs 3.251 af Secondary=0.00 cfs 0.000 af Outflow=9.19 cfs 3.251 af Peak Elev=201.54' Storage=47,185 cf Inflow=30.69 cfs 2.178 afPond P4: Basin #4 (Survey) Primary=4.63 cfs 2.056 af Secondary=0.00 cfs 0.000 af Tertiary=0.00 cfs 0.000 af Outflow=4.63 cfs 2.056 af Total Runoff Area = 34.087 ac Runoff Volume = 3.931 af Average Runoff Depth = 1.38" 61.89% Pervious = 21.096 ac 38.11% Impervious = 12.991 ac Type III 24-hr 2-yr Rainfall=3.00"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 4HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment PDA-2A: Northern & Eastern Edges of Site [49] Hint: Tc<2dt may require smaller dt Runoff = 6.60 cfs @ 12.09 hrs, Volume= 0.498 af, Depth> 0.91" Routed to Reach DP-2 : Control Point for proposed drainage Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-yr Rainfall=3.00" Area (ac) CN Description * 0.400 98 Pavement & Roof 2.344 70 Woods, Good, HSG C 3.840 74 >75% Grass cover, Good, HSG C 6.584 74 Weighted Average 6.184 93.92% Pervious Area 0.400 6.08% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment PDA-2B: TCB "Lot 13A" Project [49] Hint: Tc<2dt may require smaller dt Runoff = 7.25 cfs @ 12.08 hrs, Volume= 0.514 af, Depth> 1.59" Routed to Pond P2 : Basin #2 (Survey) Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-yr Rainfall=3.00" Area (ac) CN Description * 1.682 98 Pavement & Roof * 0.068 98 Pond/Rain Garden 0.028 61 >75% Grass cover, Good, HSG B 2.111 74 >75% Grass cover, Good, HSG C 3.889 85 Weighted Average 2.139 55.00% Pervious Area 1.750 45.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Type III 24-hr 2-yr Rainfall=3.00"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 5HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment PDA-2C: Southeast Corner of Site [49] Hint: Tc<2dt may require smaller dt Runoff = 30.69 cfs @ 12.08 hrs, Volume= 2.178 af, Depth> 1.66" Routed to Pond P4 : Basin #4 (Survey) Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-yr Rainfall=3.00" Area (ac) CN Description 7.328 98 Paved parking & roofs * 0.785 98 Detention Pond/Rain Garden * 0.733 98 Paved parking & roofs (10% Extra) 1.298 61 >75% Grass cover, Good, HSG B 5.591 74 >75% Grass cover, Good, HSG C 15.735 86 Weighted Average 6.889 43.78% Pervious Area 8.846 56.22% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment PDA-2D: Future Co-Housing Site [49] Hint: Tc<2dt may require smaller dt Runoff = 10.18 cfs @ 12.08 hrs, Volume= 0.741 af, Depth> 1.13" Routed to Pond P2 : Basin #2 (Survey) Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-yr Rainfall=3.00" Area (ac) CN Description * 1.824 98 Pavement & Roof * 0.171 98 Detention Basin 1.139 61 >75% Grass cover, Good, HSG B 0.410 70 Woods, Good, HSG C 4.335 74 >75% Grass cover, Good, HSG C 7.879 78 Weighted Average 5.884 74.68% Pervious Area 1.995 25.32% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Type III 24-hr 2-yr Rainfall=3.00"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 6HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Summary for Reach DP-2: Control Point for proposed drainage [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 34.087 ac, 38.11% Impervious, Inflow Depth > 1.32" for 2-yr event Inflow = 13.68 cfs @ 12.11 hrs, Volume= 3.749 af Outflow = 13.68 cfs @ 12.11 hrs, Volume= 3.749 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Reach S1: Drainage Swale (Upper Segment) Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Outflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Routed to Reach S2 : Drainage Swale (Middle Segment) Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 0.00 fps, Min. Travel Time= 0.0 min Avg. Velocity = 0.00 fps, Avg. Travel Time= 0.0 min Peak Storage= 0 cf @ 0.00 hrs Average Depth at Peak Storage= 0.00' Bank-Full Depth= 1.00' Flow Area= 15.0 sf, Capacity= 62.64 cfs 5.00' x 1.00' deep channel, n= 0.030 Stream, clean & straight Side Slope Z-value= 10.0 '/' Top Width= 25.00' Length= 85.0' Slope= 0.0141 '/' Inlet Invert= 202.20', Outlet Invert= 201.00' ‡ Summary for Reach S2: Drainage Swale (Middle Segment) [79] Warning: Submerged Pond P4 Primary device # 1 OUTLET by 0.38' Inflow Area = 15.735 ac, 56.22% Impervious, Inflow Depth > 1.57" for 2-yr event Inflow = 4.63 cfs @ 12.60 hrs, Volume= 2.056 af Outflow = 4.63 cfs @ 12.65 hrs, Volume= 2.053 af, Atten= 0%, Lag= 3.0 min Routed to Reach S3 : Drainage Swale (Lower Segment) Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 2.61 fps, Min. Travel Time= 1.5 min Avg. Velocity = 1.66 fps, Avg. Travel Time= 2.4 min Type III 24-hr 2-yr Rainfall=3.00"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 7HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Peak Storage= 417 cf @ 12.62 hrs Average Depth at Peak Storage= 0.38' , Surface Width= 6.40' Bank-Full Depth= 4.00' Flow Area= 84.0 sf, Capacity= 852.09 cfs 3.00' x 4.00' deep channel, n= 0.030 Earth, grassed & winding Side Slope Z-value= 4.5 '/' Top Width= 39.00' Length= 235.0' Slope= 0.0155 '/' Inlet Invert= 198.15', Outlet Invert= 194.50' ‡ Summary for Reach S3: Drainage Swale (Lower Segment) [62] Hint: Exceeded Reach S2 OUTLET depth by 3.65' @ 0.00 hrs Inflow Area = 15.735 ac, 56.22% Impervious, Inflow Depth > 1.57" for 2-yr event Inflow = 4.63 cfs @ 12.65 hrs, Volume= 2.053 af Outflow = 4.63 cfs @ 12.71 hrs, Volume= 2.049 af, Atten= 0%, Lag= 3.5 min Routed to Pond P2 : Basin #2 (Survey) Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 2.09 fps, Min. Travel Time= 1.9 min Avg. Velocity = 1.24 fps, Avg. Travel Time= 3.2 min Peak Storage= 521 cf @ 12.67 hrs Average Depth at Peak Storage= 0.23' , Surface Width= 11.23' Bank-Full Depth= 1.00' Flow Area= 15.0 sf, Capacity= 71.42 cfs 8.00' x 1.00' deep channel, n= 0.030 Earth, grassed & winding Side Slope Z-value= 7.0 '/' Top Width= 22.00' Length= 235.0' Slope= 0.0155 '/' Inlet Invert= 198.15', Outlet Invert= 194.50' ‡ Summary for Pond P2: Basin #2 (Survey) Type III 24-hr 2-yr Rainfall=3.00"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 8HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Inflow Area = 27.503 ac, 45.78% Impervious, Inflow Depth > 1.44" for 2-yr event Inflow = 19.97 cfs @ 12.09 hrs, Volume= 3.304 af Outflow = 9.19 cfs @ 12.48 hrs, Volume= 3.251 af, Atten= 54%, Lag= 23.3 min Primary = 9.19 cfs @ 12.48 hrs, Volume= 3.251 af Routed to Reach DP-2 : Control Point for proposed drainage Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routed to Reach DP-2 : Control Point for proposed drainage Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Starting Elev= 186.29' Surf.Area= 7,457 sf Storage= 2,114 cf Peak Elev= 188.26' @ 12.48 hrs Surf.Area= 9,564 sf Storage= 18,966 cf (16,852 cf above start) Plug-Flow detention time= 41.5 min calculated for 3.196 af (97% of inflow) Center-of-Mass det. time= 21.7 min ( 916.8 - 895.1 ) Volume Invert Avail.Storage Storage Description #1 186.00' 63,502 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 186.00 7,120 0 0 187.00 8,281 7,701 7,701 188.00 9,296 8,789 16,489 189.00 10,317 9,807 26,296 190.00 11,482 10,900 37,195 191.00 12,823 12,153 49,348 192.00 15,486 14,155 63,502 Device Routing Invert Outlet Devices #1 Primary 186.29'36.0" Round Culvert L= 212.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 186.29' / 181.44' S= 0.0229 '/' Cc= 0.900 n= 0.013, Flow Area= 7.07 sf #2 Device 1 186.26'12.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 186.31'12.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Device 1 188.63'6.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 #5 Secondary 191.43'Asymmetrical Weir, C= 3.27 Offset (feet) 0.00 4.50 9.00 13.50 15.00 Elev. (feet) 192.24 191.47 191.43 192.12 192.24 Primary OutFlow Max=9.19 cfs @ 12.48 hrs HW=188.26' (Free Discharge) 1=Culvert (Passes 9.19 cfs of 23.53 cfs potential flow) 2=Orifice/Grate (Orifice Controls 4.63 cfs @ 5.90 fps) 3=Orifice/Grate (Orifice Controls 4.55 cfs @ 5.80 fps) 4=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=186.29' (Free Discharge) 5=Asymmetrical Weir ( Controls 0.00 cfs) Type III 24-hr 2-yr Rainfall=3.00"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 9HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Summary for Pond P4: Basin #4 (Survey) Inflow Area = 15.735 ac, 56.22% Impervious, Inflow Depth > 1.66" for 2-yr event Inflow = 30.69 cfs @ 12.08 hrs, Volume= 2.178 af Outflow = 4.63 cfs @ 12.60 hrs, Volume= 2.056 af, Atten= 85%, Lag= 31.4 min Primary = 4.63 cfs @ 12.60 hrs, Volume= 2.056 af Routed to Reach S2 : Drainage Swale (Middle Segment) Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routed to Reach S1 : Drainage Swale (Upper Segment) Tertiary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routed to Reach DP-2 : Control Point for proposed drainage Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Starting Elev= 199.44' Surf.Area= 15,569 sf Storage= 6,494 cf Peak Elev= 201.54' @ 12.60 hrs Surf.Area= 23,212 sf Storage= 47,185 cf (40,691 cf above start) Plug-Flow detention time= 172.1 min calculated for 1.907 af (88% of inflow) Center-of-Mass det. time= 97.8 min ( 921.8 - 824.0 ) Volume Invert Avail.Storage Storage Description #1 199.00' 115,492 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 199.00 13,951 0 0 200.00 17,629 15,790 15,790 201.00 21,260 19,445 35,235 202.00 24,892 23,076 58,311 203.00 28,524 26,708 85,019 204.00 32,422 30,473 115,492 Device Routing Invert Outlet Devices #1 Primary 199.44'12.0" Round Culvert L= 93.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 199.44' / 198.15' S= 0.0139 '/' Cc= 0.900 n= 0.013 Concrete pipe, bends & connections, Flow Area= 0.79 sf #2 Secondary 202.20'8.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 #3 Tertiary 203.56'Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Elev. (feet) 203.56 204.00 Width (feet) 4.00 12.00 Type III 24-hr 2-yr Rainfall=3.00"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 10HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Primary OutFlow Max=4.63 cfs @ 12.60 hrs HW=201.54' (Free Discharge) 1=Culvert (Barrel Controls 4.63 cfs @ 5.90 fps) Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=199.44' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Tertiary OutFlow Max=0.00 cfs @ 0.00 hrs HW=199.44' (Free Discharge) 3=Custom Weir/Orifice ( Controls 0.00 cfs) Type III 24-hr 10-yr Rainfall=4.50"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 11HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=6.584 ac 6.08% Impervious Runoff Depth>1.97"Subcatchment PDA-2A: Northern & Eastern Tc=5.0 min CN=74 Runoff=15.11 cfs 1.081 af Runoff Area=3.889 ac 45.00% Impervious Runoff Depth>2.91"Subcatchment PDA-2B: TCB "Lot 13A" Tc=5.0 min CN=85 Runoff=13.26 cfs 0.942 af Runoff Area=15.735 ac 56.22% Impervious Runoff Depth>3.00"Subcatchment PDA-2C: Southeast Corner Tc=5.0 min CN=86 Runoff=55.20 cfs 3.936 af Runoff Area=7.879 ac 25.32% Impervious Runoff Depth>2.29"Subcatchment PDA-2D: Future Co-Housing Tc=5.0 min CN=78 Runoff=21.18 cfs 1.504 af Inflow=31.65 cfs 7.226 afReach DP-2: Control Point for proposed drainage Outflow=31.65 cfs 7.226 af Avg. Flow Depth=0.38' Max Vel=2.44 fps Inflow=8.29 cfs 0.447 afReach S1: Drainage Swale (Upper n=0.030 L=85.0' S=0.0141 '/' Capacity=62.64 cfs Outflow=8.26 cfs 0.447 af Avg. Flow Depth=0.66' Max Vel=3.53 fps Inflow=13.92 cfs 3.776 afReach S2: Drainage Swale (Middle n=0.030 L=235.0' S=0.0155 '/' Capacity=852.09 cfs Outflow=13.85 cfs 3.772 af Avg. Flow Depth=0.43' Max Vel=2.96 fps Inflow=13.85 cfs 3.772 afReach S3: Drainage Swale (Lower n=0.030 L=235.0' S=0.0155 '/' Capacity=71.42 cfs Outflow=13.78 cfs 3.767 af Peak Elev=189.36' Storage=30,133 cf Inflow=38.65 cfs 6.214 afPond P2: Basin #2 (Survey) Primary=22.79 cfs 6.145 af Secondary=0.00 cfs 0.000 af Outflow=22.79 cfs 6.145 af Peak Elev=202.72' Storage=77,253 cf Inflow=55.20 cfs 3.936 afPond P4: Basin #4 (Survey) Primary=5.67 cfs 3.329 af Secondary=8.29 cfs 0.447 af Tertiary=0.00 cfs 0.000 af Outflow=13.96 cfs 3.776 af Total Runoff Area = 34.087 ac Runoff Volume = 7.463 af Average Runoff Depth = 2.63" 61.89% Pervious = 21.096 ac 38.11% Impervious = 12.991 ac Type III 24-hr 10-yr Rainfall=4.50"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 12HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment PDA-2A: Northern & Eastern Edges of Site [49] Hint: Tc<2dt may require smaller dt Runoff = 15.11 cfs @ 12.08 hrs, Volume= 1.081 af, Depth> 1.97" Routed to Reach DP-2 : Control Point for proposed drainage Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.50" Area (ac) CN Description * 0.400 98 Pavement & Roof 2.344 70 Woods, Good, HSG C 3.840 74 >75% Grass cover, Good, HSG C 6.584 74 Weighted Average 6.184 93.92% Pervious Area 0.400 6.08% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment PDA-2B: TCB "Lot 13A" Project [49] Hint: Tc<2dt may require smaller dt Runoff = 13.26 cfs @ 12.07 hrs, Volume= 0.942 af, Depth> 2.91" Routed to Pond P2 : Basin #2 (Survey) Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.50" Area (ac) CN Description * 1.682 98 Pavement & Roof * 0.068 98 Pond/Rain Garden 0.028 61 >75% Grass cover, Good, HSG B 2.111 74 >75% Grass cover, Good, HSG C 3.889 85 Weighted Average 2.139 55.00% Pervious Area 1.750 45.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Type III 24-hr 10-yr Rainfall=4.50"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 13HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment PDA-2C: Southeast Corner of Site [49] Hint: Tc<2dt may require smaller dt Runoff = 55.20 cfs @ 12.07 hrs, Volume= 3.936 af, Depth> 3.00" Routed to Pond P4 : Basin #4 (Survey) Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.50" Area (ac) CN Description 7.328 98 Paved parking & roofs * 0.785 98 Detention Pond/Rain Garden * 0.733 98 Paved parking & roofs (10% Extra) 1.298 61 >75% Grass cover, Good, HSG B 5.591 74 >75% Grass cover, Good, HSG C 15.735 86 Weighted Average 6.889 43.78% Pervious Area 8.846 56.22% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment PDA-2D: Future Co-Housing Site [49] Hint: Tc<2dt may require smaller dt Runoff = 21.18 cfs @ 12.08 hrs, Volume= 1.504 af, Depth> 2.29" Routed to Pond P2 : Basin #2 (Survey) Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.50" Area (ac) CN Description * 1.824 98 Pavement & Roof * 0.171 98 Detention Basin 1.139 61 >75% Grass cover, Good, HSG B 0.410 70 Woods, Good, HSG C 4.335 74 >75% Grass cover, Good, HSG C 7.879 78 Weighted Average 5.884 74.68% Pervious Area 1.995 25.32% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Type III 24-hr 10-yr Rainfall=4.50"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 14HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Summary for Reach DP-2: Control Point for proposed drainage [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 34.087 ac, 38.11% Impervious, Inflow Depth > 2.54" for 10-yr event Inflow = 31.65 cfs @ 12.17 hrs, Volume= 7.226 af Outflow = 31.65 cfs @ 12.17 hrs, Volume= 7.226 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Reach S1: Drainage Swale (Upper Segment) [81] Warning: Exceeded Pond P4 by 0.83' @ 16.15 hrs Inflow = 8.29 cfs @ 12.46 hrs, Volume= 0.447 af Outflow = 8.26 cfs @ 12.47 hrs, Volume= 0.447 af, Atten= 0%, Lag= 1.0 min Routed to Reach S2 : Drainage Swale (Middle Segment) Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 2.44 fps, Min. Travel Time= 0.6 min Avg. Velocity = 1.27 fps, Avg. Travel Time= 1.1 min Peak Storage= 289 cf @ 12.46 hrs Average Depth at Peak Storage= 0.38' , Surface Width= 12.69' Bank-Full Depth= 1.00' Flow Area= 15.0 sf, Capacity= 62.64 cfs 5.00' x 1.00' deep channel, n= 0.030 Stream, clean & straight Side Slope Z-value= 10.0 '/' Top Width= 25.00' Length= 85.0' Slope= 0.0141 '/' Inlet Invert= 202.20', Outlet Invert= 201.00' ‡ Summary for Reach S2: Drainage Swale (Middle Segment) [79] Warning: Submerged Pond P4 Primary device # 1 OUTLET by 0.66' Inflow Area = 15.735 ac, 56.22% Impervious, Inflow Depth > 2.88" for 10-yr event Inflow = 13.92 cfs @ 12.47 hrs, Volume= 3.776 af Outflow = 13.85 cfs @ 12.51 hrs, Volume= 3.772 af, Atten= 1%, Lag= 2.1 min Routed to Reach S3 : Drainage Swale (Lower Segment) Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 3.53 fps, Min. Travel Time= 1.1 min Avg. Velocity = 1.91 fps, Avg. Travel Time= 2.0 min Type III 24-hr 10-yr Rainfall=4.50"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 15HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Peak Storage= 924 cf @ 12.49 hrs Average Depth at Peak Storage= 0.66' , Surface Width= 8.93' Bank-Full Depth= 4.00' Flow Area= 84.0 sf, Capacity= 852.09 cfs 3.00' x 4.00' deep channel, n= 0.030 Earth, grassed & winding Side Slope Z-value= 4.5 '/' Top Width= 39.00' Length= 235.0' Slope= 0.0155 '/' Inlet Invert= 198.15', Outlet Invert= 194.50' ‡ Summary for Reach S3: Drainage Swale (Lower Segment) [62] Hint: Exceeded Reach S2 OUTLET depth by 3.65' @ 0.00 hrs Inflow Area = 15.735 ac, 56.22% Impervious, Inflow Depth > 2.88" for 10-yr event Inflow = 13.85 cfs @ 12.51 hrs, Volume= 3.772 af Outflow = 13.78 cfs @ 12.55 hrs, Volume= 3.767 af, Atten= 1%, Lag= 2.4 min Routed to Pond P2 : Basin #2 (Survey) Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 2.96 fps, Min. Travel Time= 1.3 min Avg. Velocity = 1.46 fps, Avg. Travel Time= 2.7 min Peak Storage= 1,096 cf @ 12.52 hrs Average Depth at Peak Storage= 0.43' , Surface Width= 13.95' Bank-Full Depth= 1.00' Flow Area= 15.0 sf, Capacity= 71.42 cfs 8.00' x 1.00' deep channel, n= 0.030 Earth, grassed & winding Side Slope Z-value= 7.0 '/' Top Width= 22.00' Length= 235.0' Slope= 0.0155 '/' Inlet Invert= 198.15', Outlet Invert= 194.50' ‡ Summary for Pond P2: Basin #2 (Survey) Type III 24-hr 10-yr Rainfall=4.50"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 16HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Inflow Area = 27.503 ac, 45.78% Impervious, Inflow Depth > 2.71" for 10-yr event Inflow = 38.65 cfs @ 12.08 hrs, Volume= 6.214 af Outflow = 22.79 cfs @ 12.26 hrs, Volume= 6.145 af, Atten= 41%, Lag= 10.6 min Primary = 22.79 cfs @ 12.26 hrs, Volume= 6.145 af Routed to Reach DP-2 : Control Point for proposed drainage Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routed to Reach DP-2 : Control Point for proposed drainage Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Starting Elev= 186.29' Surf.Area= 7,457 sf Storage= 2,114 cf Peak Elev= 189.36' @ 12.26 hrs Surf.Area= 10,742 sf Storage= 30,133 cf (28,019 cf above start) Plug-Flow detention time= 34.7 min calculated for 6.096 af (98% of inflow) Center-of-Mass det. time= 21.6 min ( 903.5 - 881.9 ) Volume Invert Avail.Storage Storage Description #1 186.00' 63,502 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 186.00 7,120 0 0 187.00 8,281 7,701 7,701 188.00 9,296 8,789 16,489 189.00 10,317 9,807 26,296 190.00 11,482 10,900 37,195 191.00 12,823 12,153 49,348 192.00 15,486 14,155 63,502 Device Routing Invert Outlet Devices #1 Primary 186.29'36.0" Round Culvert L= 212.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 186.29' / 181.44' S= 0.0229 '/' Cc= 0.900 n= 0.013, Flow Area= 7.07 sf #2 Device 1 186.26'12.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 186.31'12.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Device 1 188.63'6.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 #5 Secondary 191.43'Asymmetrical Weir, C= 3.27 Offset (feet) 0.00 4.50 9.00 13.50 15.00 Elev. (feet) 192.24 191.47 191.43 192.12 192.24 Primary OutFlow Max=22.76 cfs @ 12.26 hrs HW=189.36' (Free Discharge) 1=Culvert (Passes 22.76 cfs of 42.69 cfs potential flow) 2=Orifice/Grate (Orifice Controls 6.10 cfs @ 7.77 fps) 3=Orifice/Grate (Orifice Controls 6.04 cfs @ 7.69 fps) 4=Broad-Crested Rectangular Weir (Weir Controls 10.62 cfs @ 2.41 fps) Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=186.29' (Free Discharge) 5=Asymmetrical Weir ( Controls 0.00 cfs) Type III 24-hr 10-yr Rainfall=4.50"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 17HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Summary for Pond P4: Basin #4 (Survey) Inflow Area = 15.735 ac, 56.22% Impervious, Inflow Depth > 3.00" for 10-yr event Inflow = 55.20 cfs @ 12.07 hrs, Volume= 3.936 af Outflow = 13.96 cfs @ 12.46 hrs, Volume= 3.776 af, Atten= 75%, Lag= 22.9 min Primary = 5.67 cfs @ 12.46 hrs, Volume= 3.329 af Routed to Reach S2 : Drainage Swale (Middle Segment) Secondary = 8.29 cfs @ 12.46 hrs, Volume= 0.447 af Routed to Reach S1 : Drainage Swale (Upper Segment) Tertiary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routed to Reach DP-2 : Control Point for proposed drainage Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Starting Elev= 199.44' Surf.Area= 15,569 sf Storage= 6,494 cf Peak Elev= 202.72' @ 12.46 hrs Surf.Area= 27,518 sf Storage= 77,253 cf (70,759 cf above start) Plug-Flow detention time= 160.3 min calculated for 3.627 af (92% of inflow) Center-of-Mass det. time= 108.2 min ( 915.3 - 807.2 ) Volume Invert Avail.Storage Storage Description #1 199.00' 115,492 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 199.00 13,951 0 0 200.00 17,629 15,790 15,790 201.00 21,260 19,445 35,235 202.00 24,892 23,076 58,311 203.00 28,524 26,708 85,019 204.00 32,422 30,473 115,492 Device Routing Invert Outlet Devices #1 Primary 199.44'12.0" Round Culvert L= 93.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 199.44' / 198.15' S= 0.0139 '/' Cc= 0.900 n= 0.013 Concrete pipe, bends & connections, Flow Area= 0.79 sf #2 Secondary 202.20'8.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 #3 Tertiary 203.56'Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Elev. (feet) 203.56 204.00 Width (feet) 4.00 12.00 Type III 24-hr 10-yr Rainfall=4.50"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 18HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Primary OutFlow Max=5.67 cfs @ 12.46 hrs HW=202.72' (Free Discharge) 1=Culvert (Barrel Controls 5.67 cfs @ 7.21 fps) Secondary OutFlow Max=8.26 cfs @ 12.46 hrs HW=202.72' (Free Discharge) 2=Broad-Crested Rectangular Weir (Weir Controls 8.26 cfs @ 1.98 fps) Tertiary OutFlow Max=0.00 cfs @ 0.00 hrs HW=199.44' (Free Discharge) 3=Custom Weir/Orifice ( Controls 0.00 cfs) Type III 24-hr 25-yr Rainfall=5.25"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 19HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=6.584 ac 6.08% Impervious Runoff Depth>2.56"Subcatchment PDA-2A: Northern & Eastern Tc=5.0 min CN=74 Runoff=19.78 cfs 1.406 af Runoff Area=3.889 ac 45.00% Impervious Runoff Depth>3.60"Subcatchment PDA-2B: TCB "Lot 13A" Tc=5.0 min CN=85 Runoff=16.30 cfs 1.166 af Runoff Area=15.735 ac 56.22% Impervious Runoff Depth>3.70"Subcatchment PDA-2C: Southeast Corner Tc=5.0 min CN=86 Runoff=67.54 cfs 4.850 af Runoff Area=7.879 ac 25.32% Impervious Runoff Depth>2.92"Subcatchment PDA-2D: Future Co-Housing Tc=5.0 min CN=78 Runoff=27.04 cfs 1.919 af Inflow=47.67 cfs 9.080 afReach DP-2: Control Point for proposed drainage Outflow=47.67 cfs 9.080 af Avg. Flow Depth=0.55' Max Vel=2.98 fps Inflow=17.28 cfs 0.971 afReach S1: Drainage Swale (Upper n=0.030 L=85.0' S=0.0141 '/' Capacity=62.64 cfs Outflow=17.22 cfs 0.971 af Avg. Flow Depth=0.84' Max Vel=4.04 fps Inflow=23.12 cfs 4.674 afReach S2: Drainage Swale (Middle n=0.030 L=235.0' S=0.0155 '/' Capacity=852.09 cfs Outflow=23.03 cfs 4.670 af Avg. Flow Depth=0.56' Max Vel=3.45 fps Inflow=23.03 cfs 4.670 afReach S3: Drainage Swale (Lower n=0.030 L=235.0' S=0.0155 '/' Capacity=71.42 cfs Outflow=22.91 cfs 4.665 af Peak Elev=189.80' Storage=34,975 cf Inflow=47.97 cfs 7.750 afPond P2: Basin #2 (Survey) Primary=36.58 cfs 7.674 af Secondary=0.00 cfs 0.000 af Outflow=36.58 cfs 7.674 af Peak Elev=203.03' Storage=85,805 cf Inflow=67.54 cfs 4.850 afPond P4: Basin #4 (Survey) Primary=5.90 cfs 3.703 af Secondary=17.28 cfs 0.971 af Tertiary=0.00 cfs 0.000 af Outflow=23.19 cfs 4.674 af Total Runoff Area = 34.087 ac Runoff Volume = 9.342 af Average Runoff Depth = 3.29" 61.89% Pervious = 21.096 ac 38.11% Impervious = 12.991 ac Type III 24-hr 25-yr Rainfall=5.25"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 20HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment PDA-2A: Northern & Eastern Edges of Site [49] Hint: Tc<2dt may require smaller dt Runoff = 19.78 cfs @ 12.08 hrs, Volume= 1.406 af, Depth> 2.56" Routed to Reach DP-2 : Control Point for proposed drainage Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-yr Rainfall=5.25" Area (ac) CN Description * 0.400 98 Pavement & Roof 2.344 70 Woods, Good, HSG C 3.840 74 >75% Grass cover, Good, HSG C 6.584 74 Weighted Average 6.184 93.92% Pervious Area 0.400 6.08% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment PDA-2B: TCB "Lot 13A" Project [49] Hint: Tc<2dt may require smaller dt Runoff = 16.30 cfs @ 12.07 hrs, Volume= 1.166 af, Depth> 3.60" Routed to Pond P2 : Basin #2 (Survey) Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-yr Rainfall=5.25" Area (ac) CN Description * 1.682 98 Pavement & Roof * 0.068 98 Pond/Rain Garden 0.028 61 >75% Grass cover, Good, HSG B 2.111 74 >75% Grass cover, Good, HSG C 3.889 85 Weighted Average 2.139 55.00% Pervious Area 1.750 45.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Type III 24-hr 25-yr Rainfall=5.25"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 21HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment PDA-2C: Southeast Corner of Site [49] Hint: Tc<2dt may require smaller dt Runoff = 67.54 cfs @ 12.07 hrs, Volume= 4.850 af, Depth> 3.70" Routed to Pond P4 : Basin #4 (Survey) Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-yr Rainfall=5.25" Area (ac) CN Description 7.328 98 Paved parking & roofs * 0.785 98 Detention Pond/Rain Garden * 0.733 98 Paved parking & roofs (10% Extra) 1.298 61 >75% Grass cover, Good, HSG B 5.591 74 >75% Grass cover, Good, HSG C 15.735 86 Weighted Average 6.889 43.78% Pervious Area 8.846 56.22% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment PDA-2D: Future Co-Housing Site [49] Hint: Tc<2dt may require smaller dt Runoff = 27.04 cfs @ 12.08 hrs, Volume= 1.919 af, Depth> 2.92" Routed to Pond P2 : Basin #2 (Survey) Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-yr Rainfall=5.25" Area (ac) CN Description * 1.824 98 Pavement & Roof * 0.171 98 Detention Basin 1.139 61 >75% Grass cover, Good, HSG B 0.410 70 Woods, Good, HSG C 4.335 74 >75% Grass cover, Good, HSG C 7.879 78 Weighted Average 5.884 74.68% Pervious Area 1.995 25.32% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Type III 24-hr 25-yr Rainfall=5.25"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 22HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Summary for Reach DP-2: Control Point for proposed drainage [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 34.087 ac, 38.11% Impervious, Inflow Depth > 3.20" for 25-yr event Inflow = 47.67 cfs @ 12.15 hrs, Volume= 9.080 af Outflow = 47.67 cfs @ 12.15 hrs, Volume= 9.080 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Reach S1: Drainage Swale (Upper Segment) [81] Warning: Exceeded Pond P4 by 0.78' @ 16.50 hrs Inflow = 17.28 cfs @ 12.36 hrs, Volume= 0.971 af Outflow = 17.22 cfs @ 12.37 hrs, Volume= 0.971 af, Atten= 0%, Lag= 0.9 min Routed to Reach S2 : Drainage Swale (Middle Segment) Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 2.98 fps, Min. Travel Time= 0.5 min Avg. Velocity = 1.53 fps, Avg. Travel Time= 0.9 min Peak Storage= 492 cf @ 12.36 hrs Average Depth at Peak Storage= 0.55' , Surface Width= 16.02' Bank-Full Depth= 1.00' Flow Area= 15.0 sf, Capacity= 62.64 cfs 5.00' x 1.00' deep channel, n= 0.030 Stream, clean & straight Side Slope Z-value= 10.0 '/' Top Width= 25.00' Length= 85.0' Slope= 0.0141 '/' Inlet Invert= 202.20', Outlet Invert= 201.00' ‡ Summary for Reach S2: Drainage Swale (Middle Segment) [79] Warning: Submerged Pond P4 Primary device # 1 OUTLET by 0.84' Inflow Area = 15.735 ac, 56.22% Impervious, Inflow Depth > 3.56" for 25-yr event Inflow = 23.12 cfs @ 12.37 hrs, Volume= 4.674 af Outflow = 23.03 cfs @ 12.40 hrs, Volume= 4.670 af, Atten= 0%, Lag= 1.7 min Routed to Reach S3 : Drainage Swale (Lower Segment) Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 4.04 fps, Min. Travel Time= 1.0 min Avg. Velocity = 1.98 fps, Avg. Travel Time= 2.0 min Type III 24-hr 25-yr Rainfall=5.25"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 23HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Peak Storage= 1,341 cf @ 12.38 hrs Average Depth at Peak Storage= 0.84' , Surface Width= 10.57' Bank-Full Depth= 4.00' Flow Area= 84.0 sf, Capacity= 852.09 cfs 3.00' x 4.00' deep channel, n= 0.030 Earth, grassed & winding Side Slope Z-value= 4.5 '/' Top Width= 39.00' Length= 235.0' Slope= 0.0155 '/' Inlet Invert= 198.15', Outlet Invert= 194.50' ‡ Summary for Reach S3: Drainage Swale (Lower Segment) [62] Hint: Exceeded Reach S2 OUTLET depth by 3.65' @ 0.00 hrs Inflow Area = 15.735 ac, 56.22% Impervious, Inflow Depth > 3.56" for 25-yr event Inflow = 23.03 cfs @ 12.40 hrs, Volume= 4.670 af Outflow = 22.91 cfs @ 12.43 hrs, Volume= 4.665 af, Atten= 0%, Lag= 2.0 min Routed to Pond P2 : Basin #2 (Survey) Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 3.45 fps, Min. Travel Time= 1.1 min Avg. Velocity = 1.53 fps, Avg. Travel Time= 2.6 min Peak Storage= 1,565 cf @ 12.41 hrs Average Depth at Peak Storage= 0.56' , Surface Width= 15.83' Bank-Full Depth= 1.00' Flow Area= 15.0 sf, Capacity= 71.42 cfs 8.00' x 1.00' deep channel, n= 0.030 Earth, grassed & winding Side Slope Z-value= 7.0 '/' Top Width= 22.00' Length= 235.0' Slope= 0.0155 '/' Inlet Invert= 198.15', Outlet Invert= 194.50' ‡ Summary for Pond P2: Basin #2 (Survey) Type III 24-hr 25-yr Rainfall=5.25"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 24HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Inflow Area = 27.503 ac, 45.78% Impervious, Inflow Depth > 3.38" for 25-yr event Inflow = 47.97 cfs @ 12.08 hrs, Volume= 7.750 af Outflow = 36.58 cfs @ 12.39 hrs, Volume= 7.674 af, Atten= 24%, Lag= 18.9 min Primary = 36.58 cfs @ 12.39 hrs, Volume= 7.674 af Routed to Reach DP-2 : Control Point for proposed drainage Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routed to Reach DP-2 : Control Point for proposed drainage Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Starting Elev= 186.29' Surf.Area= 7,457 sf Storage= 2,114 cf Peak Elev= 189.80' @ 12.39 hrs Surf.Area= 11,255 sf Storage= 34,975 cf (32,862 cf above start) Plug-Flow detention time= 31.4 min calculated for 7.626 af (98% of inflow) Center-of-Mass det. time= 20.0 min ( 889.5 - 869.5 ) Volume Invert Avail.Storage Storage Description #1 186.00' 63,502 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 186.00 7,120 0 0 187.00 8,281 7,701 7,701 188.00 9,296 8,789 16,489 189.00 10,317 9,807 26,296 190.00 11,482 10,900 37,195 191.00 12,823 12,153 49,348 192.00 15,486 14,155 63,502 Device Routing Invert Outlet Devices #1 Primary 186.29'36.0" Round Culvert L= 212.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 186.29' / 181.44' S= 0.0229 '/' Cc= 0.900 n= 0.013, Flow Area= 7.07 sf #2 Device 1 186.26'12.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 186.31'12.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Device 1 188.63'6.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 #5 Secondary 191.43'Asymmetrical Weir, C= 3.27 Offset (feet) 0.00 4.50 9.00 13.50 15.00 Elev. (feet) 192.24 191.47 191.43 192.12 192.24 Primary OutFlow Max=36.53 cfs @ 12.39 hrs HW=189.80' (Free Discharge) 1=Culvert (Passes 36.53 cfs of 48.29 cfs potential flow) 2=Orifice/Grate (Orifice Controls 6.60 cfs @ 8.40 fps) 3=Orifice/Grate (Orifice Controls 6.54 cfs @ 8.33 fps) 4=Broad-Crested Rectangular Weir (Weir Controls 23.39 cfs @ 3.32 fps) Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=186.29' (Free Discharge) 5=Asymmetrical Weir ( Controls 0.00 cfs) Type III 24-hr 25-yr Rainfall=5.25"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 25HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Summary for Pond P4: Basin #4 (Survey) Inflow Area = 15.735 ac, 56.22% Impervious, Inflow Depth > 3.70" for 25-yr event Inflow = 67.54 cfs @ 12.07 hrs, Volume= 4.850 af Outflow = 23.19 cfs @ 12.36 hrs, Volume= 4.674 af, Atten= 66%, Lag= 17.0 min Primary = 5.90 cfs @ 12.36 hrs, Volume= 3.703 af Routed to Reach S2 : Drainage Swale (Middle Segment) Secondary = 17.28 cfs @ 12.36 hrs, Volume= 0.971 af Routed to Reach S1 : Drainage Swale (Upper Segment) Tertiary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routed to Reach DP-2 : Control Point for proposed drainage Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Starting Elev= 199.44' Surf.Area= 15,569 sf Storage= 6,494 cf Peak Elev= 203.03' @ 12.36 hrs Surf.Area= 28,631 sf Storage= 85,805 cf (79,311 cf above start) Plug-Flow detention time= 144.3 min calculated for 4.515 af (93% of inflow) Center-of-Mass det. time= 98.8 min ( 900.1 - 801.3 ) Volume Invert Avail.Storage Storage Description #1 199.00' 115,492 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 199.00 13,951 0 0 200.00 17,629 15,790 15,790 201.00 21,260 19,445 35,235 202.00 24,892 23,076 58,311 203.00 28,524 26,708 85,019 204.00 32,422 30,473 115,492 Device Routing Invert Outlet Devices #1 Primary 199.44'12.0" Round Culvert L= 93.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 199.44' / 198.15' S= 0.0139 '/' Cc= 0.900 n= 0.013 Concrete pipe, bends & connections, Flow Area= 0.79 sf #2 Secondary 202.20'8.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 #3 Tertiary 203.56'Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Elev. (feet) 203.56 204.00 Width (feet) 4.00 12.00 Type III 24-hr 25-yr Rainfall=5.25"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 26HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Primary OutFlow Max=5.90 cfs @ 12.36 hrs HW=203.03' (Free Discharge) 1=Culvert (Barrel Controls 5.90 cfs @ 7.52 fps) Secondary OutFlow Max=17.23 cfs @ 12.36 hrs HW=203.03' (Free Discharge) 2=Broad-Crested Rectangular Weir (Weir Controls 17.23 cfs @ 2.61 fps) Tertiary OutFlow Max=0.00 cfs @ 0.00 hrs HW=199.44' (Free Discharge) 3=Custom Weir/Orifice ( Controls 0.00 cfs) Type III 24-hr 100-yr Rainfall=7.00"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 27HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=6.584 ac 6.08% Impervious Runoff Depth>4.04"Subcatchment PDA-2A: Northern & Eastern Tc=5.0 min CN=74 Runoff=31.20 cfs 2.216 af Runoff Area=3.889 ac 45.00% Impervious Runoff Depth>5.25"Subcatchment PDA-2B: TCB "Lot 13A" Tc=5.0 min CN=85 Runoff=23.42 cfs 1.701 af Runoff Area=15.735 ac 56.22% Impervious Runoff Depth>5.36"Subcatchment PDA-2C: Southeast Corner Tc=5.0 min CN=86 Runoff=96.33 cfs 7.032 af Runoff Area=7.879 ac 25.32% Impervious Runoff Depth>4.47"Subcatchment PDA-2D: Future Co-Housing Tc=5.0 min CN=78 Runoff=41.10 cfs 2.936 af Inflow=85.48 cfs 13.570 afReach DP-2: Control Point for proposed drainage Outflow=85.48 cfs 13.570 af Avg. Flow Depth=0.86' Max Vel=3.81 fps Inflow=44.23 cfs 2.330 afReach S1: Drainage Swale (Upper n=0.030 L=85.0' S=0.0141 '/' Capacity=62.64 cfs Outflow=44.10 cfs 2.330 af Avg. Flow Depth=1.20' Max Vel=4.95 fps Inflow=50.45 cfs 6.816 afReach S2: Drainage Swale (Middle n=0.030 L=235.0' S=0.0155 '/' Capacity=852.09 cfs Outflow=49.83 cfs 6.811 af Avg. Flow Depth=0.84' Max Vel=4.31 fps Inflow=49.83 cfs 6.811 afReach S3: Drainage Swale (Lower n=0.030 L=235.0' S=0.0155 '/' Capacity=71.42 cfs Outflow=49.29 cfs 6.804 af Peak Elev=191.47' Storage=55,699 cf Inflow=80.42 cfs 11.442 afPond P2: Basin #2 (Survey) Primary=65.31 cfs 11.351 af Secondary=0.09 cfs 0.001 af Outflow=65.40 cfs 11.352 af Peak Elev=203.64' Storage=103,930 cf Inflow=96.33 cfs 7.032 afPond P4: Basin #4 (Survey) Primary=6.35 cfs 4.485 af Secondary=44.23 cfs 2.330 af Tertiary=0.32 cfs 0.002 af Outflow=50.90 cfs 6.818 af Total Runoff Area = 34.087 ac Runoff Volume = 13.886 af Average Runoff Depth = 4.89" 61.89% Pervious = 21.096 ac 38.11% Impervious = 12.991 ac Type III 24-hr 100-yr Rainfall=7.00"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 28HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment PDA-2A: Northern & Eastern Edges of Site [49] Hint: Tc<2dt may require smaller dt Runoff = 31.20 cfs @ 12.08 hrs, Volume= 2.216 af, Depth> 4.04" Routed to Reach DP-2 : Control Point for proposed drainage Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=7.00" Area (ac) CN Description * 0.400 98 Pavement & Roof 2.344 70 Woods, Good, HSG C 3.840 74 >75% Grass cover, Good, HSG C 6.584 74 Weighted Average 6.184 93.92% Pervious Area 0.400 6.08% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment PDA-2B: TCB "Lot 13A" Project [49] Hint: Tc<2dt may require smaller dt Runoff = 23.42 cfs @ 12.07 hrs, Volume= 1.701 af, Depth> 5.25" Routed to Pond P2 : Basin #2 (Survey) Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=7.00" Area (ac) CN Description * 1.682 98 Pavement & Roof * 0.068 98 Pond/Rain Garden 0.028 61 >75% Grass cover, Good, HSG B 2.111 74 >75% Grass cover, Good, HSG C 3.889 85 Weighted Average 2.139 55.00% Pervious Area 1.750 45.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Type III 24-hr 100-yr Rainfall=7.00"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 29HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment PDA-2C: Southeast Corner of Site [49] Hint: Tc<2dt may require smaller dt Runoff = 96.33 cfs @ 12.07 hrs, Volume= 7.032 af, Depth> 5.36" Routed to Pond P4 : Basin #4 (Survey) Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=7.00" Area (ac) CN Description 7.328 98 Paved parking & roofs * 0.785 98 Detention Pond/Rain Garden * 0.733 98 Paved parking & roofs (10% Extra) 1.298 61 >75% Grass cover, Good, HSG B 5.591 74 >75% Grass cover, Good, HSG C 15.735 86 Weighted Average 6.889 43.78% Pervious Area 8.846 56.22% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment PDA-2D: Future Co-Housing Site [49] Hint: Tc<2dt may require smaller dt Runoff = 41.10 cfs @ 12.08 hrs, Volume= 2.936 af, Depth> 4.47" Routed to Pond P2 : Basin #2 (Survey) Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=7.00" Area (ac) CN Description * 1.824 98 Pavement & Roof * 0.171 98 Detention Basin 1.139 61 >75% Grass cover, Good, HSG B 0.410 70 Woods, Good, HSG C 4.335 74 >75% Grass cover, Good, HSG C 7.879 78 Weighted Average 5.884 74.68% Pervious Area 1.995 25.32% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Type III 24-hr 100-yr Rainfall=7.00"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 30HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Summary for Reach DP-2: Control Point for proposed drainage [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 34.087 ac, 38.11% Impervious, Inflow Depth > 4.78" for 100-yr event Inflow = 85.48 cfs @ 12.11 hrs, Volume= 13.570 af Outflow = 85.48 cfs @ 12.11 hrs, Volume= 13.570 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Reach S1: Drainage Swale (Upper Segment) [81] Warning: Exceeded Pond P4 by 0.71' @ 17.30 hrs Inflow = 44.23 cfs @ 12.21 hrs, Volume= 2.330 af Outflow = 44.10 cfs @ 12.22 hrs, Volume= 2.330 af, Atten= 0%, Lag= 0.6 min Routed to Reach S2 : Drainage Swale (Middle Segment) Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 3.81 fps, Min. Travel Time= 0.4 min Avg. Velocity = 1.73 fps, Avg. Travel Time= 0.8 min Peak Storage= 986 cf @ 12.21 hrs Average Depth at Peak Storage= 0.86' , Surface Width= 22.11' Bank-Full Depth= 1.00' Flow Area= 15.0 sf, Capacity= 62.64 cfs 5.00' x 1.00' deep channel, n= 0.030 Stream, clean & straight Side Slope Z-value= 10.0 '/' Top Width= 25.00' Length= 85.0' Slope= 0.0141 '/' Inlet Invert= 202.20', Outlet Invert= 201.00' ‡ Summary for Reach S2: Drainage Swale (Middle Segment) [79] Warning: Submerged Pond P4 Primary device # 1 OUTLET by 1.20' Inflow Area = 15.735 ac, 56.22% Impervious, Inflow Depth > 5.20" for 100-yr event Inflow = 50.45 cfs @ 12.22 hrs, Volume= 6.816 af Outflow = 49.83 cfs @ 12.25 hrs, Volume= 6.811 af, Atten= 1%, Lag= 1.9 min Routed to Reach S3 : Drainage Swale (Lower Segment) Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 4.95 fps, Min. Travel Time= 0.8 min Avg. Velocity = 2.13 fps, Avg. Travel Time= 1.8 min Type III 24-hr 100-yr Rainfall=7.00"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 31HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Peak Storage= 2,377 cf @ 12.23 hrs Average Depth at Peak Storage= 1.20' , Surface Width= 13.82' Bank-Full Depth= 4.00' Flow Area= 84.0 sf, Capacity= 852.09 cfs 3.00' x 4.00' deep channel, n= 0.030 Earth, grassed & winding Side Slope Z-value= 4.5 '/' Top Width= 39.00' Length= 235.0' Slope= 0.0155 '/' Inlet Invert= 198.15', Outlet Invert= 194.50' ‡ Summary for Reach S3: Drainage Swale (Lower Segment) [62] Hint: Exceeded Reach S2 OUTLET depth by 3.65' @ 0.00 hrs Inflow Area = 15.735 ac, 56.22% Impervious, Inflow Depth > 5.19" for 100-yr event Inflow = 49.83 cfs @ 12.25 hrs, Volume= 6.811 af Outflow = 49.29 cfs @ 12.28 hrs, Volume= 6.804 af, Atten= 1%, Lag= 1.7 min Routed to Pond P2 : Basin #2 (Survey) Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 4.31 fps, Min. Travel Time= 0.9 min Avg. Velocity = 1.66 fps, Avg. Travel Time= 2.4 min Peak Storage= 2,721 cf @ 12.26 hrs Average Depth at Peak Storage= 0.84' , Surface Width= 19.70' Bank-Full Depth= 1.00' Flow Area= 15.0 sf, Capacity= 71.42 cfs 8.00' x 1.00' deep channel, n= 0.030 Earth, grassed & winding Side Slope Z-value= 7.0 '/' Top Width= 22.00' Length= 235.0' Slope= 0.0155 '/' Inlet Invert= 198.15', Outlet Invert= 194.50' ‡ Summary for Pond P2: Basin #2 (Survey) Type III 24-hr 100-yr Rainfall=7.00"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 32HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Inflow Area = 27.503 ac, 45.78% Impervious, Inflow Depth > 4.99" for 100-yr event Inflow = 80.42 cfs @ 12.11 hrs, Volume= 11.442 af Outflow = 65.40 cfs @ 12.39 hrs, Volume= 11.352 af, Atten= 19%, Lag= 16.5 min Primary = 65.31 cfs @ 12.39 hrs, Volume= 11.351 af Routed to Reach DP-2 : Control Point for proposed drainage Secondary = 0.09 cfs @ 12.39 hrs, Volume= 0.001 af Routed to Reach DP-2 : Control Point for proposed drainage Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Starting Elev= 186.29' Surf.Area= 7,457 sf Storage= 2,114 cf Peak Elev= 191.47' @ 12.39 hrs Surf.Area= 14,080 sf Storage= 55,699 cf (53,585 cf above start) Plug-Flow detention time= 27.0 min calculated for 11.303 af (99% of inflow) Center-of-Mass det. time= 18.0 min ( 867.0 - 849.0 ) Volume Invert Avail.Storage Storage Description #1 186.00' 63,502 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 186.00 7,120 0 0 187.00 8,281 7,701 7,701 188.00 9,296 8,789 16,489 189.00 10,317 9,807 26,296 190.00 11,482 10,900 37,195 191.00 12,823 12,153 49,348 192.00 15,486 14,155 63,502 Device Routing Invert Outlet Devices #1 Primary 186.29'36.0" Round Culvert L= 212.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 186.29' / 181.44' S= 0.0229 '/' Cc= 0.900 n= 0.013, Flow Area= 7.07 sf #2 Device 1 186.26'12.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 186.31'12.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Device 1 188.63'6.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 #5 Secondary 191.43'Asymmetrical Weir, C= 3.27 Offset (feet) 0.00 4.50 9.00 13.50 15.00 Elev. (feet) 192.24 191.47 191.43 192.12 192.24 Primary OutFlow Max=65.25 cfs @ 12.39 hrs HW=191.47' (Free Discharge) 1=Culvert (Inlet Controls 65.25 cfs @ 9.23 fps) 2=Orifice/Grate (Passes < 8.20 cfs potential flow) 3=Orifice/Grate (Passes < 8.16 cfs potential flow) 4=Broad-Crested Rectangular Weir (Passes < 95.00 cfs potential flow) Secondary OutFlow Max=0.04 cfs @ 12.39 hrs HW=191.47' (Free Discharge) 5=Asymmetrical Weir (Weir Controls 0.04 cfs @ 0.25 fps) Type III 24-hr 100-yr Rainfall=7.00"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 33HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Summary for Pond P4: Basin #4 (Survey) Inflow Area = 15.735 ac, 56.22% Impervious, Inflow Depth > 5.36" for 100-yr event Inflow = 96.33 cfs @ 12.07 hrs, Volume= 7.032 af Outflow = 50.90 cfs @ 12.21 hrs, Volume= 6.818 af, Atten= 47%, Lag= 8.3 min Primary = 6.35 cfs @ 12.21 hrs, Volume= 4.485 af Routed to Reach S2 : Drainage Swale (Middle Segment) Secondary = 44.23 cfs @ 12.21 hrs, Volume= 2.330 af Routed to Reach S1 : Drainage Swale (Upper Segment) Tertiary = 0.32 cfs @ 12.21 hrs, Volume= 0.002 af Routed to Reach DP-2 : Control Point for proposed drainage Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Starting Elev= 199.44' Surf.Area= 15,569 sf Storage= 6,494 cf Peak Elev= 203.64' @ 12.21 hrs Surf.Area= 31,001 sf Storage= 103,930 cf (97,436 cf above start) Plug-Flow detention time= 120.7 min calculated for 6.669 af (95% of inflow) Center-of-Mass det. time= 83.9 min ( 874.9 - 791.0 ) Volume Invert Avail.Storage Storage Description #1 199.00' 115,492 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 199.00 13,951 0 0 200.00 17,629 15,790 15,790 201.00 21,260 19,445 35,235 202.00 24,892 23,076 58,311 203.00 28,524 26,708 85,019 204.00 32,422 30,473 115,492 Device Routing Invert Outlet Devices #1 Primary 199.44'12.0" Round Culvert L= 93.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 199.44' / 198.15' S= 0.0139 '/' Cc= 0.900 n= 0.013 Concrete pipe, bends & connections, Flow Area= 0.79 sf #2 Secondary 202.20'8.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 #3 Tertiary 203.56'Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Elev. (feet) 203.56 204.00 Width (feet) 4.00 12.00 Type III 24-hr 100-yr Rainfall=7.00"17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group Page 34HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC Primary OutFlow Max=6.34 cfs @ 12.21 hrs HW=203.63' (Free Discharge) 1=Culvert (Barrel Controls 6.34 cfs @ 8.08 fps) Secondary OutFlow Max=43.88 cfs @ 12.21 hrs HW=203.63' (Free Discharge) 2=Broad-Crested Rectangular Weir (Weir Controls 43.88 cfs @ 3.84 fps) Tertiary OutFlow Max=0.27 cfs @ 12.21 hrs HW=203.63' (Free Discharge) 3=Custom Weir/Orifice (Weir Controls 0.27 cfs @ 0.84 fps) Table of Contents17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC TABLE OF CONTENTS Project Reports 1 Routing Diagram 2 Area Listing (selected nodes) 2-yr Event 3 Node Listing 4 Subcat PDA-2A: Northern & Eastern Edges of Site 5 Subcat PDA-2B: TCB "Lot 13A" Project 5 Subcat PDA-2C: Southeast Corner of Site 6 Subcat PDA-2D: Future Co-Housing Site 6 Reach DP-2: Control Point for proposed drainage 7 Reach S1: Drainage Swale (Upper Segment) 7 Reach S2: Drainage Swale (Middle Segment) 8 Reach S3: Drainage Swale (Lower Segment) 8 Pond P2: Basin #2 (Survey) 9 Pond P4: Basin #4 (Survey) 10-yr Event 11 Node Listing 12 Subcat PDA-2A: Northern & Eastern Edges of Site 13 Subcat PDA-2B: TCB "Lot 13A" Project 13 Subcat PDA-2C: Southeast Corner of Site 14 Subcat PDA-2D: Future Co-Housing Site 14 Reach DP-2: Control Point for proposed drainage 15 Reach S1: Drainage Swale (Upper Segment) 15 Reach S2: Drainage Swale (Middle Segment) 16 Reach S3: Drainage Swale (Lower Segment) 16 Pond P2: Basin #2 (Survey) 17 Pond P4: Basin #4 (Survey) 25-yr Event 19 Node Listing 20 Subcat PDA-2A: Northern & Eastern Edges of Site 21 Subcat PDA-2B: TCB "Lot 13A" Project 21 Subcat PDA-2C: Southeast Corner of Site 22 Subcat PDA-2D: Future Co-Housing Site 22 Reach DP-2: Control Point for proposed drainage 23 Reach S1: Drainage Swale (Upper Segment) 23 Reach S2: Drainage Swale (Middle Segment) 24 Reach S3: Drainage Swale (Lower Segment) 24 Pond P2: Basin #2 (Survey) 25 Pond P4: Basin #4 (Survey) 100-yr Event 27 Node Listing 28 Subcat PDA-2A: Northern & Eastern Edges of Site Table of Contents17-058-Village Hill Co-Housing_As Built 2022-12-13 Printed 12/15/2022Prepared by Berkshire Design Group HydroCAD® 10.20-2g s/n 00752 © 2022 HydroCAD Software Solutions LLC 29 Subcat PDA-2B: TCB "Lot 13A" Project 29 Subcat PDA-2C: Southeast Corner of Site 30 Subcat PDA-2D: Future Co-Housing Site 30 Reach DP-2: Control Point for proposed drainage 31 Reach S1: Drainage Swale (Upper Segment) 31 Reach S2: Drainage Swale (Middle Segment) 32 Reach S3: Drainage Swale (Lower Segment) 32 Pond P2: Basin #2 (Survey) 33 Pond P4: Basin #4 (Survey)