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16B-001 Drainage Analysis & Report Warner Hill Estates January 10 20050 Drainage Analysis and Report for Warner Hill Estates Bridge Street Northampton, Massachusetts January 10, 2005 Prepared by: The Berkshire Design Group jnc . 4 Allen Place, Northampton, Massachusetts 01060 Prepared for: John C. Chakalos Chakolos Investments, LLC Windsor, CT Warner Hill Estates, Aliampton, MA — January 10, 2005 I. Introduction The following report presents an analysis of the stormwater management system for the proposed Warner Hill Estates development (the site) located on Bridge Road in Northampton, Massachusetts. The proposed project is an Open Space Development providing 46 residential units. The project parcel is approximately 24 acres. The purpose of this analysis is to determine 2, 10, and 100 -year peak flow rates and quantities for the site in both the pre- and post - development conditions and to determine the potential impact of any increases in stormwater runoff from the site that may occur as a result of the site development. II. Site Terrain and Soils The project site is located on the north side of Bridge Road near the intersection of Locust Street. The project site abuts the JFK Middle School along its east boundary and the VA Hospital along its north boundary. The site is comprised of a flat plain area (glacial outwash) in the southern portion of the site and a sloping terrain (glacial till) located to the north area. There are no wetlands or other resource areas located on the site. The subsurface conditions at the site are as follows: The USDA Soil Survey of Hampshire County, Massachusetts, Central Part report classifies the site soils as (see attached soil map): • (PaD, PaC, PcD, PcQ Paxton. Deep, well drained soils on glaciated uplands. Soils formed in glacial till. Hydrologic Group: C Flood Risk: none Depth to Water Table: 1.5' -2.5' Depth to Bedrock: >60" • (HgA) Hinckley. Deep, excessively drained soils on glacial outwash plains. Hydrologic Group: A Flood Risk: none Depth to Water Table: > 6' Depth to Bedrock: > 60" Page 1 Warner Hill Estates, l Wampton, MA — January 10, 2005 A series of eight test pits were conducted on site to determine subsurface conditions in several critical areas (see attached test pit logs in Appendix A). The purpose of the test pits was to evaluate the site for the existance of ledge, the ability of the site to support stormwater drainage components, and for classifications of the soils in the proposed entrance road. In general, the test pits confirmed the .USDA Soil Survey findings for the site. The test pit logs are attached in Appendix A). III. Calculations & Design Drainage calculations were performed on Hydrocad Stormwater Modeling System version 6.0 using Soil Conservation Service (SCS) TR -20 methodology. The SCS method is based on rainfall observations, which were used to develop the Intensity - Duration- Frequency relationship, or IDF curve. The mass curve is a dimensionless distribution of rainfall over time, which indicates the fraction of the rainfall event that occurs at a given time within a 24 -hour precipitation event. This synthetic distribution develops peak rates for storms of varying duration and intensities. The SCS distribution provides a cumulative rainfall at any point in time and allows volume dependent routing runoff calculations to occur. The calculations are included in the appendices. The watershed boundaries for calculation purposes are divided according to the proposed site grading, the natural limits of the drainage areas, and the property downstream boundaries. The curve numbers (CNs) and times of concentration for the existing and proposed subcatchment areas are based on the soil type and the existing and proposed cover conditions at the site. The soil hydrologic group assumed for the site is noted in section II. Watershed sub - catchment areas, runoff coefficients and watercourse slopes are based on The Berkshire Design Group site plans dated January 2005. Calculations were performed for the 2 -, 10 -, and 100 -year frequency storms under existing and proposed conditions. The results of the calculations are presented in Section V. Page 2 Warner Hill Estates, ARampton, MA January 10, 2005 As shown in the Table 2, the stormwater peak flows in the 2 -, 10 -, and 100 -year storm events at the north property line will not be increased as a result of the proposed development. III. Existing Conditions The existing drainage patterns for the site follow a north to south flow pattern. There are four main watersheds, or subcatchements in the existing conditions (Refer to the Existing Drainage Area Map, Figure 2, attached.) Runoff generated in the upper (northwest) area of the site generally sheet flows to the west boundary to the former railroad bed. Runoff from the upper west - central area of the site sheet flows to the nearly level plain area where it is retained in an existing depression. The model shows that runoff will be contained in the depression in the 2- and 10 -year storm events; however, the depression will be overtopped in the 100 -year storm event resulting in a discharge into the JFK parking lot. The model shows runoff from the upper east - central area flowing to the nearly level plain area to the east of the depression where it sheet flows to the east property line and infiltrates during small storm events and flows into the JFK parking area during moderate and large storm events. The upper east area drains to the JFK athletic fields. There are no point source discharges of stormwater in existing conditions. IV. Proposed Conditions Water Quantity The stormwater flows in proposed conditions have been designed to emulate the flow patterns in existing conditions. Two retention /detention basins have been designed to receive, retain, and infiltrate a majority of the runoff in proposed conditions. Field infiltration tests revealed infiltration rates of 3.3 min /inch and 2 min /inch. As a conservative measure, an infiltration rate of 10 min /inch was used in the calculations. During large storm events some discharges from the site are unavoidable. As such, the proposed retention /detention basins are connected to the closed drainage system in Bridge Road. This discharge emulates the existing discharge to the JFK Middle School parking while providing a controlled outlet that doesn't affect the school's drainage system. Page 3 Warner Hill Estates, N§hampton, MA January 10, 2005 The peak flows and volumes in existing and proposed conditions are presented in Table 1 below. Table 1. Peak Flow and Volume Summary Table Water Quality Several BMPs have been incorporated into the design of the development's stormwater management system. Theses include; street sweeping, deep sump hooded catch basins, stormwater treatment chambers, and sediment forebays. The following table shows the estimated sediment removal for the stormwater management system: Page 4 *Names in parentheses refer to HydroCad model and calculations. Warner Hill Estates, MA J Table 2. Estimated Sediment Removal Total TSS Removal = 89.9% 10, 2005 The primary mechanism for controlling stormwater runoff is retention and infiltration; as such, care has been taken to provide BMP's that can achieve more than the prescribed 80% TSS removal. VL Summary The proposed development has been designed so that proposed stormwater flow patterns will emulate existing patterns. In existing conditions, the site retains and infiltrates a significant amount of stormwater with discharges to the JKF School parking lot occrrung during large storm events. The proposed stormwater management system has been designed to retain and infiltrate stormwater to match existing conditions. Some release of stormwater is unavoidable in large storm events; thus a connection to the closed drainage system in Bridge Road is proposed to emulate the current discharge to the JFK School parking lot. Treatment of stormwater is provided through the use of several BMP mechanisms. The resulting TSS removal rate for the site is estimated to be 89.9 %. Page 5 Remaining BMP Estimated Removal TSS (Initial: 100%) Street Sweeping 10% 90% Deep Sump Catch Basins 25% 67.5% Treatment Chamber 80% 13.5% Sediment Forebays 25% 10.1% Total TSS Removal = 89.9% 10, 2005 The primary mechanism for controlling stormwater runoff is retention and infiltration; as such, care has been taken to provide BMP's that can achieve more than the prescribed 80% TSS removal. VL Summary The proposed development has been designed so that proposed stormwater flow patterns will emulate existing patterns. In existing conditions, the site retains and infiltrates a significant amount of stormwater with discharges to the JKF School parking lot occrrung during large storm events. The proposed stormwater management system has been designed to retain and infiltrate stormwater to match existing conditions. Some release of stormwater is unavoidable in large storm events; thus a connection to the closed drainage system in Bridge Road is proposed to emulate the current discharge to the JFK School parking lot. Treatment of stormwater is provided through the use of several BMP mechanisms. The resulting TSS removal rate for the site is estimated to be 89.9 %. Page 5 VA Hospital MY LV chool � I M7 The Sheet Title: Reference: Sheet Number. Drainage Areas - Existing Cond itions Berkshire Design 4 Allen Place Northampton, Massachusetts 01060 Group, Inc. (413 82-7000 • FAX (413) 582-7005 WARNER HILL ESTATES Date: Scale: NORTHAMPTON MASSACHUSETTS 01/10/05 1 1 =200' 1 • VA Hospital . n �o f s'ti i T - - I I I I --F - I -- - I-- i--j -- - L - I - -- --�— -- C - k� -- - 1" eORESa - -- . 0 0 I a r 1140'i Jjot 12PCP Reference: Sheet Number" Holding Tank Submit I r� Data: Scale: ov,65 1 L C - k� -- - 1" eORESa - -- . 0 0 I a r 1140'i Jjot 12PCP 1 -UMMARY OF FINDING EXPLORATORY TEST PITS FOR THE WARNER PARCEL - NORTHAMPTON Prepared By The Berkshire Design Group, Inc. April 30, 2004 Background: The following summarizes the findings of the soil exploratory test pits performed at the Warner Property, 20 Bridge Road, Northampton, MA. A series of eight (8) test pits were performed at the site over the course of two days, April 27 and April 30. The purpose of the test pits was to evaluate the site for the existence of ledge, the ability of the site to support stormwater drainage components, and to meet the Northampton Subdivision submission requirements for soil classification within a proposed subdivision road. Summary of Findings: The site is generally made up of two land forms; a lower plain comprised of grassed gentle slopes and an upper area comprised of steeper wooded slopes. Lower Plain Area: Test Pits 1, 2, 3, and 4 were performed in the lower area. The soil material in this area is generally comprised of loose sands and gravels and was classified as outwash. Groundwater was not observed in any of the test pits at the time of testing. Ledge was not encountered in any of the test pits in this area. Upper Area: Test Pits 5, 6, 7, and 8 were performed in the upper area. The soil material in this area is generally comprised of firm loamy sand and gravels (glacial till). Groundwater was encountered in Test Pits 6, 7, and 8 and was classified as perched. Ledge was not encountered in any of the test pits in this area. Large stones and boulders were encountered. It may be useful to note that the machine operator, Don Wade, had performed a significant amount of construction involving excavation at the Veteran's Administration Hospital over the last few decades and he reported that in his experience ledge had not been encountered at the VA Hospital site. Refer to Test Pit Logs and Test Pit Location Plan Limitations: The information contained in these findings is based on isolated test pits, observation of surface conditions, and interviews with the property owner and others and do not purport to be conclusive. Variations in subsurface conditions and fluctuations of groundwater table are possible. The Berkshire Design Group, Inc. r I Are — \`,7 r 40 New Hou ve 411,496 SF 9.447 Ac , J r TP #8. i I ,4 _ p - - Ope S pace v `� - _ _ — _ _ Open Spac _ -... - - - _r. _� f . -.. �_ 93,350 SF ' 196,081 SF '." "— - _ ' '—= J � � � -- -- 4.501 Ac ` - - — -_ - �— 2.143 Ac Existing House I i •' c za 5 ACeES ___ _ - - __ - Emergency Road .i Proposed TP #l� I Detention Area i, _ I Existing Paved Driveway - 0,`" 13,460 SF 0.309A TP #2 Proposed ' , _ Active R Open Space 213,575 SF Proposed - - -- - �`.;' - - — - - 4.903 Ac Test Pit Sub division Road - -_ Location Plan 35,237 SF 0.809 Ac , Existing Fronta Lot 7 Proposed _ cte -car :,�, Detention Area 13,781 SF -� v J •al Pro sed v 0.316 Ac -TPA Fron O t B Legend: - 25,997 SF TP#1 Propose ' 0.597 Ac Frontage Lot_ A - o TEST PIT LOCATION (APPROX.) 0.490 SF 0.490 Ac BRIDGE ROAD - - -- - - -- Location Address or Lot No. Warner Parcel, Northampton, MA 7', D;*n Performed By M.D'Urso, The Berkshire Design Group Witnessed By: Deep Hole Number TP 1 Date: 04 -27 -04 Time: 9:00am Weather Clear 60F Location (identify on site plan) Prop. East Detention Basin - See Plan Land Use Mowed lawn Slope ( %) See Plan Surface Stones Placed stones Vegetation Mowed lawn Landform Position on Landscape (sketch on back) Distances from:See Plan Open Water Body Feet Drainage way Feet Possible Wet Area Feet Property Line Feet Drinking Water Well Feet Other DEEP OBSERVATION HOLE LOG * Depth from Soil Soil Texture Soil Color Soil Mottling Other Surface(Inches) Horizon (USDA) (Munsell) 9:46 (Structure, Stones, Boulders, 4 min Rate: < 2 min/inch Consistency, % Gravel 0 -9" A VFSL Drk Brwn n/o Massive, friable, roots 9 " -25" B, FSL Reddish n/o Massive, Friable Brwn 25" -120" C, Med Brwn Loose, 50% cobbles and gravel, Sand some silt, some stones in lower 4 ' iviiivirvivrvi vi c nv�.�o nCl,(VInCL/ HI Cvr -riT rmutruz LL) UIJI Parent Material (geologic) Outwash Depth to Bedrock: > 120" Depth to Groundwater: Standing Water in the Hole: n/o Weeping from Pit Face: n/o Estimated Seasonal High Ground Water: >120" Percolation Test: Depth to Pere: 48" Start Pre -Soak 12 ": 9:31 End Pre -Soak 12 9:40 Time at 12 ": 9:40 Time at 9 ": 9:42 Time at 6 ": 9:46 Time (9 " -6 "): 4 min Rate: < 2 min/inch Location Address or Lot No. Warner Parcel, Northampton, MA Test Pits Performed By M.D'Urso, The Berkshire Design Group Witnessed By: Deep Hole Number TP 2 Date: 04 -27 -04 Time: 9:00am Weather Clear 65F Location (identify on site plan) Area South of Prop. East Det. Basin - See Plan Land Use Mowed lawn Slope ( %) See Plan Surface Stones Placed stones Vegetation Mowed lawn Landform Position on Landscape (sketch on back) Distances from:See Plan Open Water Body Feet Drainage way Feet Possible Wet Area Feet Property Line Feet Drinking Water Well Feet Other DEEP OBSERVATION HOLE LOG * Depth from Soil Soil Texture Soil Color Soil Mottling Other Surface(Inches) Horizon (USDA) (Munsell) (Structure, Stones, Boulders, Consistency, % Gravel 0 -9" A P VFSL Drk Brwn n/o Massive, friable, roots 9 " -84" C, Med- Brwn n/o Loose, 40% cobbles and gravel, Sand some silt ivmvnnvm vi c i wLLJ nCl..(VInEU MI EVErIT rriurvacv UIJrIJJAL AHtzA Parent Material (geologic) Outwash Depth to Bedrock: > 84" Depth to Groundwater: Standing Water in the Hole: n/o Weeping from Pit Face: n/o Estimated Seasonal High Ground Water: >84" Percolation Test: Depth to Pere: Start Pre -Soak 12 ": End Pre -Soak 12 ": Time at 12 ": Time at 9 ": Time at 6 ": Rate: No Test Performed Location Address or Lot No. Warner Parcel, Northampton, MA 'r — * D4*tn Performed By M.D'Urso, The Berkshire Design Group Witnessed By: Deep Hole Number TP 3 Date: 04 -30 -04 Time: 9:00am Weather Clear 65F Location (identify on site plan) Prop. Road - See Plan Land Use Mowed lawn Slope ( %) See Plan Vegetation Mowed lawn Landform Position on Landscape (sketch on back) Distances from:See Plan Open Water Body Feet Drainage way Possible Wet Area Feet Property Line Drinking Water Well Feet Other Feet Feet DEEP OBSERVATION HOLE LOG * Depth from Soil Soil Texture Soil Color Soil Mottling Other Surface(Inches) Horizon (USDA) (Munsell) (Structure, Stones, Boulders, Consistency, % Gravel 0 -14" A VFSL Drk Brwn n/o Massive, friable, roots 14 " -26" B FSL Reddish n/o Massive, Friable Brwn 26 " -96" C, Med Brwn n/o Loose, 40% cobbles and gravel, Sand some silt, some stones ivnivim Vm vi c nvLCJ nCl,(V1�1CU H I C V CY'f T rYiVl"VJCU UIJrIJJHL HHtH Parent Material (geologic) Outwash Depth to Bedrock: > 96" Depth to Groundwater: Standing Water in the Hole: n/o Weeping from Pit Face: n/o Estimated Seasonal High Ground Water: >96" Percolation Test: No test performed Depth to Pere: Start Pre -Soak 12 End Pre -Soak 12 ": Time at 12 ": Time at 9 ": Time at 6 ": Time (9 " -6 "): Rate: Surface Stones Placed stones • Location Address or Lot No. Warner Parcel, Northampton, MA Test Pits Performed By M.D'Urso, The Berkshire Design Group Witnessed By: Deep Hole Number TP 4 Date: 04 -30 -04 Time: 10:30am Weather Clear 70F Location (identify on site plan) Prop. West of Prop. West Det. Basin - See Plan Land Use Slope ( %) See Plan Surface Stones Placed stones Vegetation Overgrowth Landform Position on Landscape (sketch on back) Distances from:See Plan Open Water Body Feet Drainage way Feet Possible Wet Area Feet Property Line Feet Drinking Water Well Feet Other DEEP OBSERVATION HOLE LOG * Depth from Soil Soil Texture Soil Color Soil Mottling Other Surface(Inches) Horizon (USDA) (Munsell) (Structure, Stones, Boulders, Consistency, % Gravel 0 -18" A VFSL Drk Brwn n/o Massive, friable, roots 18 " -36" B W VFSL Reddish n/o Massive, Friable, some roots Brwn 36 " -77" C, Med Brwn n/o Loose, 50% cobbles and gravel, Sand some stones, some silt (more silt content than TP 1 -TP 3) ivnivimum Ur z rIULCJ tSCIdUINLU A I r_Vr_ iY F'HUF'USLU U16HU6AL AHLA Parent Material (geologic) Outwash Depth to Groundwater: Standing Water in the Hole Estimated Seasonal High Ground Water: >77" Percolation Test: Depth to Pere: Start Pre -Soak 12" End Pre -Soak 12" Time at 12 ": Time at 9 ": Time at 6 ": Time (9 " -6 "): Rate: Comments: n/o 56" 10:15 10:30 10:30 10:40 10:50 10 min 3.3 min/inch 6 gallons of water used to maintain 12" during pre -soak Depth to Bedrock: > 77" Weeping from Pit Face: n/o • Location Address or Lot No. Warner Parcel, Northampton, MA Test Pits Performed By M.D'Urso, The Berkshire Design Group Witnessed By: Deep Hole Number TP 5 Date: 04 -30 -04 Time: 11:20am Weather Clear 70F Location (identify on site plan) Prop. West of Prop. West Det. Basin - See Plan Land Use Slope ( %) See Plan Surface Stones Placed stones Vegetation Lawn Landform Position on Landscape (sketch on back) Distances from:See Plan Open Water Body Feet Drainage way Feet Possible Wet Area Feet Property Line Feet Drinking Water Well Feet Other DEEP OBSERVATION HOLE LOG Depth from Soil Soil Texture Soil Color Soil Mottling Other Surface(Inches) Horizon (USDA) (Munsell) (Structure, Stones, Boulders, Consistency, % Gravel 0 -10" A VFSL Dr Brwn n/o Massive, friable, roots 10 " -29" B, FSL Reddish n/o Massive, Friable, many stones at Brwn interface with C, 29 " -80" C, LS Grey Brwn n/o Firm in place, platy, firm in hand, moist, 50% cobbles and gravel, some stones * RAIAIIRAI IRA f n i /li rn n °• ..... -• -• --• •�- n i v u i 1 r nvrvoLV LJIJr - UOML HYiCH Parent Material (geologic) Glacial Till Depth to Groundwater: Standing Water in the Hole: n/o Estimated Seasonal High Ground Water: >80" Percolation Test: Depth to Pere: Start Pre -Soak 12 End Pre -Soak 12 Time at 12 Time at 9 ": Time at 6 ": Rate: Depth to Bedrock: > 80" Weeping from Pit Face: n/o No Test Performed r1 L.J Location Address or Lot No. Warner Parcel, Northampton, MA Test Pits Performed By M.D'Urso, The Berkshire Design Group Witnessed By: Deep Hole Number TP 6 Date: 04 -30 -04 Time: 1:00pm Weather P- Cloudy 70F Location (identify on site plan) Prop. Road - See Plan Land Use Slope ( %) See Plan Surface Stones some Vegetation Lawn Landform Position on Landscape (sketch on back) Distances from:See Plan Open Water Body Feet Drainage way Feet Possible Wet Area Feet Property Line Feet Drinking Water Well Feet Other DEEP OBSERVATION HOLE LOG Depth from Soil Soil Texture Soil Color Soil Mottling Other Surface(Inches) Horizon (USDA) (Munsell) (Structure, Stones, Boulders, 0 -7" A FSL Drk Brwn n/o Consistency, % Gravel Forest mat, Massive, friable, roots 7 " -16" B, FSL Reddish n/o Massive, Friable, some roots Brwn 16 " -96" C, LS Grey Brwn n/o 20% cobbles & gravel, some stones, damp, weeping around interface of B, & C, * MInIIKAI IRA (lC o Uni cC n=r�i iinrn nT r Parent Material (geologic) Glacial Till Depth to Bedrock: > 96" Depth to Groundwater: Standing Water in the Hole: n/o Weeping from Pit Face: 36" (perched) Estimated Seasonal High Ground Water: >96" Percolation Test: No Test Performed Depth to Pere: Start Pre -Soak 12 ": End Pre -Soak 12 Time at 12 Time at 9 ": Time at 6 Rate: r - � U Location Address or Lot No. Warner Parcel, Northampton, MA Performed By M.D'Urso, The Berkshire Design Group Deep Hole Number TP 7 Date: 04 -30 -04 Location (identify on site plan) Prop. Road - See Plan Land Use Slope ( %) See Plan Vegetation Wooded, Pines, some low growth deciduous Landform Witnessed By: Time: 2:00pm Weather P- Cloudv 70F Surface Stones Many stones & boulders Position on Landscape (sketch on back) Distances from:See Plan Open Water Body Feet Drainage way Feet Possible Wet Area Feet Property Line Feet Drinking Water Well Feet Other DEEP OBSERVATION HOLE LOG * Depth from Soil Soil Texture Soil Color Soil Mottling Other Surface(Inches) Horizon (USDA) (Munsell) (Structure, Stones, Boulders, Consistency, % Gravel 0 -4" A FSL Drk Brwn n/o Forest mat, Massive, friable, many roots 4 " -12" B, FSL Reddish n/o Massive, Friable, some roots Brwn 12" -138" C, LS Grey Brwn n/o Firm in place, platy, stones, few boulders, 35% cobbles & gravel, lower 6' appears to be more dense, some weeping at 65" t RAIAIIRAI IAA ­ ... ..... -•• ­111 I nvF voLV vlar VJHL HY'fCH Parent Material (geologic) Glacial Till Depth to Bedrock: > 138" Depth to Groundwater: Standing Water in the Hole: n/o Weeping from Pit Face: 65" (perched) Estimated Seasonal High Ground Water: >138" Percolation Test: Depth to Pere: Start Pre -Soak 12 ": End Pre -Soak 12 Time at 12 Time at 9 ": Time at 6 ": Rate: No Test Performed • Location Address or Lot No. Warner P arcel, Northampton, MA 7', D�tn Performed By M.D'Urso, The Berkshire Design Group Deep Hole Number TP 8 Date: 04 -30 -04 Location (identify on site plan) Prop. Road - See Plan Land Use Slope ( %) See Plan Vegetation Wooded, Pines, some low growth deciduous Landform Soil Mottling Position on Landscape (sketch on back) Surface(Inches) Distances from:See Plan (USDA) Open Water Body Feet Possible Wet Area Feet Drinking Water Well Feet Witnessed By: Time: 2:30pm Weather P- Cloudy 70F Surface Stones Many stones & boulders Drainage way Feet Property Line Feet Other DEEP OBSERVATION HOLE LOG * Depth from Soil Soil Texture Soil Color Soil Mottling Other Surface(Inches) Horizon (USDA) (Munsell) (Structure, Stones, Boulders, Consistency, % Gravel 0 -4" A FSL Drk Brwn n/o Forest mat, Massive, friable, many roots 4 " -12" B FSL Reddish n/o Massive, Friable, some roots Brwn 12" -120" C, LS Grey Brwn n/o Firm in place, platy, stones, few boulders, 35% cobbles & gravel, lower 6' appears to be more KAIA11KA1 IAA dense, some weeping at 56" ••• I Iv..w I i��,tvn iw n I LvLn 1 r"nlJr"VJCL/ IJIJI'VJHL /AHLA Parent Material (geologic) Glacial Till Depth to Bedrock: > 120" Depth to Groundwater: Standing Water in the Hole: n/o Weeping from Pit Face: 56" (perched) Estimated Seasonal High Ground Water: >120" Percolation Test: Depth to Pere: Start Pre -Soak 12 ": End Pre -Soak 12 Time at 12 Time at 9 ": Time at 6 ": Rate: No Test Performed Warner Hill Estates 0 — January 10, 2005 Northampton, Massachusetts Proposed Stormwater Management System Operation & Maintenance Plan During Construction The Contractor shall be responsible for inspection and maintenance during construction. At all times, siltation fabric fencing, stakes and hay bales sufficient to construct a sedimentation control barrier a minimum of 50 feet long will be stockpiled on the site in order to repair 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 rain storms until the completion of construction. In case of any noted breach or failure, the Contractor shall immediately make appropriate repairs to any erosion control system and notify the engineer of any problems involving stormwater management systems. A rain storm shall be defined as all or one of the following: • Any storm in which rain is predicted to last for twelve 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 one - half inch. • 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 Conservation Commission shall be notified of any significant failure of stormwater management systems and erosion and sediment control measures and shall be notified of any release of pollutants to a water body (stream, brook, pond, etc.). Warner Hill Estates 0 _ January 10, 2005 Northampton, Massachusetts The Contractor shall remove the sediment from behind the fence of the sedimentation control barrier when the accumulated sediment has reached one - half of the original installed height of the barrier. Post - Construction Stormwater Management System Owner: The Developer, John C. Chakalos Chakalos Investments, LLC 52 Overlook Drive Windsor, CT 06095 shall own the stormwater management system until such time that the Homeowners Association is established or the City of Northampton Department of Public Works accepts the roadway and /or stormwater management system. Party Responsible for Operation & Maintenance: The Developer, John C. Chakalos Chakalos Investments, LLC 52 Overlook Drive Windsor, CT 06095 shall be responsible for the stormwater management system until such time that the Homeowners Association is established, at which time the Homeowners Association will or the City of Northampton Department of Public Works accepts the roadway and /or stormwater management system. Inspection & Maintenance Schedule: 1) Street Sweeping Street and parking area sweeping shall take place twice annually. 2) Grassed Swales Swales shall be mowed at least once per growing season to prevent establishment of woody growth and other undesirable plants that inhibit proper performance. Grass vegetation should not be cut shorter than 4 ". It is important not to engage in Warner Hill Estates 0 January 10, 2005 Northampton, Massachusetts excessive mowing operations, as this keeps the grass too short and decreases the efficiency of the vegetation to reduce runoff borne sediments and velocities. Sediment and debris shall be removed manually at least once per year before the vegetation is adversely impacted. 3) Hooded Catch Basin and/or Drain Manhole with Sump Oil and water separators should be inspected at least four times per year and cleaned annually or more often if required. Oil and sediments should be removed and disposed of in accordance with local, state and federal guidelines and regulations. In the case of an oil or bulk pollutant release, the system must be cleaned immediately following the spill and the proper authorities notified. 4) Stormwater Treatment Chamber The Stormwater Treatment System requires minimal routine maintenance; however, it is important that the system be properly inspected and cleaned when necessary in order to function at its best. The rate at which the system collects pollutants will depend more heavily on site activities than the size of the unit, e.g. heavy winter sanding will cause the grit chamber to fill more quickly, but regular sweeping will slow accumulation. The water quality treatment system shall consist of Stormceptor or equal treatment chambers. For more detail of how the Stormceptor should be maintained see the Stormceptor Owner Manual. 4) Retention/Detention Basins (The following recommendations follow the MADEP Stormwater Policy guidelines.) Inspections a. Initial six months of use. Inspect infiltration basins after every major storm event. Examine for stabilization and function, including determination of the duration of water standing in the basin, any sediment erosion, excessive compaction of soils, or low spots. b. Twice per year. Examine basin for the following: differential settlement, cracking, erosion, leakage, or tree growth on embankments, condition of riprap, sediment accumulation, and health of turf. Any adverse conditions noted during any inspections shall be addressed by repair or reconsideration of design components. War ner Hill Estates 0 Tannary 10 ?001; ivortnampton, Massachusetts Mowing and General Maintenance Occasional mowing (1 -2 times per year min.) shall be performed on the side slopes and basin bottom. Accumulated grass clippings and/or organic matter and trash and debris shall be removed. Any clogged surface areas can be loosened by deep tilling; tilled areas must be immediately revegetated. Tilling may be used in this manner for no more than two consecutive maintenance periods. Thereafter, sediment in the clogged areas shall be removed, liner material replaced, and revegetation established. Dredging /Sediment Removal Accumulated sediment shall be removed from the basin at five (5) year intervals, or as required to maintain the function of the stormwater management system as designed. During this process and until the disturbed sediment has settled, the outlet pipe shall be sealed so as to minimize the risk of conveying sediment beyond the basin. Sediment forebays shall be inspected as noted above and sediment removed when fifty percent (50 %) of its original capacity has been compromised, or once per year, whichever occurs first. A story board shall be installed in the forebay to allow for easy determination of sediment depth. : 1 OCP :1 / \ 0 p 1/ 300 P �40P [4 :OC ]P S u obc, t E,,c:h. WHE Type 111 24 -hr Rainfall= 2.95" Prepared by The Berkshire Design Group, Inc. Page 1 HydroCADO 6.00 s/n 000752 © 1986 -2001 Applied Microcomputer Systems 1/10/2005 Time span =0.00 -24.00 hrs, dt =0.05 hrs, 481 points Runoff by SCS TR -20 method, UH =SCS, Type III 24 -hr Rainfall= 2.95" Reach routing by Stor- Ind +Trans method - Pond routing by Stor -Ind method Subcatchment 1 E: West Area Tc =25.7 min CN =71 Area =9.298 ac Runoff= 4.25 cfs 0.563 of Subcatchment 2E: West - Central Area Tc =10.8 min CN =60 Area =4.360 ac Runoff= 0.67 cfs 0.114 of Subcatchment 3E: East Central Area Tc =27.3 min CN =62 Area = 11.948 ac Runoff= 2.02 cfs 0.373 of Subcatchment 4E: East Area Tc =15.3 min CN =70 Area =1.752 ac Runoff= 0.90 cfs 0.100 of Subcatchment 10P: West Area Tc =22.3 min CN =72 Area =5.406 ac Runoff= 2.84 cfs 0.349 of Subcatchment 20P: West - Central Area Tc =12.5 min CN =88 Area =4.470 ac Runoff= 7.47 cfs 0.659 of Subcatchment 30P: East - Central Area Tc =26.1 min CN =72 Area = 15.546 ac Runoff= 7.65 cfs 1.001 of Subcatchment 31 P: Paved Roadway Tc =5.0 min CN =98 Area =0.165 ac Runoff= 0.47 cfs 0.037 of Subcatchment 40P: East Area Tc =15.3 min CN =70 Area =1.752 ac Runoff= 0.90 cfs 0.100 of Reach 1CP: Control Point Inflow= 4.25 cfs 0.563 of Outflow= 4.25 cfs 0.563 of Reach 1 R: Reach - Depression Overflow Path Inflow= 0.00 cfs 0.000 of Length= 260.0' Max Vel= 0.0 fps Capacity= 30.98 cfs Outflow= 0.00 cfs 0.000 of Reach 2CP: Control Point - Overflow to JFK P -Lot Inflow= 2.02 cfs 0.373 of Outflow= 2.02 cfs 0.373 of Reach 4CP: Control Point Inflow= 0.90 cfs 0.100 of Outflow= 0.90 cfs 0.100 of Reach 10CP: Control Point Inflow= 2.84 cfs 0.349 of Outflow= 2.84 cfs 0.349 of Reach 20CP: Control Point - Bridge St Drainage System Inflow= 0.00 cfs 0.000 of Outflow= 0.00 cfs 0.000 of • WHE Type 111 24 -hr Rainfall= 2.95" Prepared by The Berkshire Design Group, Inc. Page 2 HydroCADO 6.00 s/n 000752 © 1986 -2001 Applied Microcomputer Systems 1/10/2005 Reach 40CP: Control Point Inflow= 0.90 cfs 0.100 of Outflow= 0.90 cfs 0.100 of Pond 1 B: Existing Depression Peak Storage= 836 cf Inflow= 0.67 cfs 0.114 of Discarded= 0.26 cfs 0.112 of Primary= 0.00 cfs 0.000 of Outflow= 0.26 cfs 0.112 of Pond 2013: West Basin Peak Storage= 13,663 cf Inflow= 7.47 cfs 0.659 of Discarded= 0.67 cfs 0.595 of Primary= 0.00 cfs 0.000 of Secondary= 0.00 cfs 0.000 of Outflow= 0.67 cfs 0.595 of Pond 30B: East Basin Peak Storage= 14,845 cf Inflow= 7.78 cfs 1.038 of Discarded= 1.71 cfs 1.037 of Primary= 0.00 cfs 0.000 of Outflow= 1.71 cfs 1.037 of Runoff Area = 54.697 ac Volume = 3.296 of Average Depth = 0.72" • WHE Type 111 24 -hr Rainfall= 2.95" Prepared by The Berkshire Design Group, Inc. Page 3 HydroCADO6.00 s/n 000752 © 1986 -2001 Applied Microcomputer Systems 1/10/2005 Subcatchment 1 E: West Area Runoff = 4.25 cfs @ 12.41 hrs, Volume= 0.563 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 2.95" Area (ac) CN Description 0.260 74 >75% Grass cover, Good, HSG C 0.266 98 Roof and Paved Driveway 8.772 70 Woods, Good, HSG C 9.298 71 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) ( ft/ft) (ft/sec) (cfs) 16.0 100 0.0470 0.1 Sheet Flow, 0.220 98 Pond 100 -yr Flood Elev 4.360 Woods: Light underbrush n= 0.400 P2= 2.90" 5.3 365 0.0530 1.2 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 4.4 465 0.1230 1.8 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 25.7 930 Total Subcatchment 2E: West - Central Area Runoff = 0.67 cfs @ 12.32 hrs, Volume= 0.114 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 2.95" Area (ac) CN Description 0.089 98 Roofs 0.254 74 >75% Grass cover, Good, HSG C 2.129 70 Woods, Good, HSG C 1.668 39 >75% Grass cover, Good, HSG A 0.220 98 Pond 100 -yr Flood Elev 4.360 60 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.4 100 0.1000 0.3 Sheet Flow, Grass: Short n=0.150 P2=2.90" 2.7 430 0.1400 2.6 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 2.7 180 0.0250 1.1 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 10.8 710 Total WHE Type 111 24 -hr Rainfall= 2.95" Prepared by The Berkshire Design Group, Inc. Page 4 HydroCADO6.00 s/n 000752 © 1986 -2001 Applied Microcomputer Systems 1/10/2005 Subcatchment 3E: East Central Area Runoff = 2.02 cfs @ 12.54 hrs, Volume= 0.373 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 2.95" Area ac CN Description 0.105 98 Roofs 2.588 74 >75% Grass cover, Good, HSG C 5.832 70 Woods, Good, HSG C 3.380 39 >75% Grass cover, Good, HSG A 0.043 30 Woods G ood, HSG A 11.948 62 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 14.9 100 0.0560 0.1 Sheet Flow, 4.2 450 0.1260 1.8 Woods: Light underbrush n= 0.400 P2= 2.90" Shallow Concentrated Flow, Woodland Kv= 5.0 fps 1.9 285 0.1260 2.5 Shallow Concentrated Flow, 15.3 575 Total Short Grass Pasture Kv= 7.0 fps 6.3 300 0.0130 0.8 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 27.3 1,135 Total Subcatchment 4E: East Area Runoff = 0.90 cfs @ 12.25 hrs, Volume= 0.100 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 2.95" Area (ac) CN Description 1.752 70 Woods, Good, HSG C Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.8 100 0.1000 0.1 Sheet Flow, 3.5 475 0.2000 2.2 Woods: Light underbrush n= 0.400 P2= 2.90" Shallow Concentrated Flow, Woodland Kv= 5.0 fps 15.3 575 Total WHE Type 111 24 -hr Rainfall- 2.95" Prepared by The Berkshire Design Group, Inc. Page 5 HydroCADO 6.00 s/n 000752 © 1986 -2001 Applied Microcomputer Systems 1/10/2005 Subcatchment 101 West Area Runoff = 2.84 cfs @ 12.35 hrs, Volume= 0.349 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 2.95" Area (ac) CN Description 4.308 70 Woods, Good, HSG C 0.783 74 >75% Grass cover, Good, HSG C 0.315 98 Roofs, Pavement 5.406 72 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 16.0 100 0.0470 0.1 Sheet Flow, 3.6 325 0.0910 1.5 Woods: Light underbrush n= 0.400 P2= 2.90" Shallow Concentrated Flow, 2.1 255 0.0820 2.0 Woodland Kv= 5.0 fps 1.7 187 0.1340 1.8 Shallow Concentrated Flow, 5.0 Woodland Kv= 5.0 fps 1.0 132 0.1890 2.2 Shallow Concentrated Flow, Woodland Kv= 5.0 fqs 22.3 744 Total Subcatchment 201 West - Central Area Runoff = 7.47 cfs @ 12.17 hrs, Volume= 0.659 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 2.95" Area ac) CN Description 2.016 98 Roofs 1.736 74 >75% Grass cover, Good, HSG C 0.074 70 Woods, Good, HSG C 0.000 39 >75% Grass cover, Good, HSG A 0.017 30 Woods, Good, HSG A 0.627 98 Pond at 100 -vr Peak Elev 4.470 88 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/f0 (ft/sec) (cfs) 5.4 50 0.0250 0.2 Sheet Flow, Grass: Short n= 0.150 P2= 2.90" 2.1 255 0.0820 2.0 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 5.0 Direct Entrv. 12.5 305 Total WHE Type 111 24 -hr Rainfall - azll Prepared by The Berkshire Design Group, Inc. Page 6 HydroCADO 6.00 s/n 000752 © 1986 -2001 Applied Microcomputer Systems 1/10/2005 Subcatchment 30P: East - Central Area Runoff = 7.65 cfs @ 12.41 hrs, Volume= 1.001 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 2.95" Area ac) CN Description 2.138 98 Roofs - Pavement 5.888 74 >75% Grass cover, Good, HSG C 2.675 70 Woods, Good, HSG C 3.113 39 >75% Grass cover, Good, HSG A 0.110 30 Woods, Good, HSG A 1.622 98 Pond at 100 -vr Peak Elev 15.546 72 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.8 100 0.1000 0.1 Sheet Flow, 4.5 460 0.1160 1.7 Woods: Light underbrush n= 0.400 P2= 2.90" Shallow Concentrated Flow, Woodland Kv= 5.0 fps 0.4 65 0.2660 2.6 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 4.3 440 0.1170 1.7 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 5.1 210 0.0190 0.7 Shallow Concentrated Flow, Woodland Kv= 5.0 fas 26.1 1,275 Total Subcatchment 31 P: Paved Roadway Runoff = 0.47 cfs @ 12.07 hrs, Volume= 0.037 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 2.95" Area (ac) CN Description 0.165 98 Pavement Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, • WHE Type 111 24 -hr Rainfall= 2.95" Prepared by The Berkshire Design Group, Inc. Page 7 HydroCADO 6.00 s/n 000752 © 1986 -2001 Applied Microcomputer Systems 1/10/2005 Subcatchment 40P: East Area Runoff = 0.90 cfs @ 12.25 hrs, Volume= 0.100 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 2.95" Area (ac) CN Description 1.752 70 Woods, Good, HSG C Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.8 100 0.1000 0.1 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 2.90" 3.5 475 0.2000 2.2 Shallow Concentrated Flow, Woodland Kv= 5.0 fas 15.3 575 Total Reach 1 CP: Control Point Inflow = 4.25 cfs @ 12.41 hrs, Volume= 0.563 of Outflow = 4.25 cfs @ 12.41 hrs, Volume= 0.563 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Reach 1 R: Reach - Depression Overflow Path Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Outflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Max. Velocity= 0.0 fps, Min. Travel Time= 0.0 min Avg. Velocity = 0.0 fps, Avg. Travel Time= 0.0 min Peak Depth= 0.00' Capacity at bank full= 30.98 cfs Inlet Invert= 287.75', Outlet Invert= 286.71' 100.00' x 0.25' deep channel, n= 0.030 Length= 260.0' Slope= 0.0040'/' Reach 2CP: Control Point - Overflow to JFK P -Lot Inflow = 2.02 cfs @ 12.54 hrs, Volume= 0.373 of Outflow = 2.02 cfs @ 12.54 hrs, Volume= 0.373 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs • WHE Type 111 24 -hr Rainfall= 2.95" Prepared by The Berkshire Design Group, Inc. Page 8 HydroCADO 6.00 s/n 000752 C 1986 -2001 Applied Microcomputer Systems 1/10/2005 Reach 4CP: Control Point Inflow = 0.90 cfs @ 12.25 hrs, Volume= 0.100 of Outflow = 0.90 cfs @ 12.25 hrs, Volume= 0.100 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Reach 10CP: Control Point Inflow = 2.84 cfs @ 12.35 hrs, Volume= 0.349 of Outflow = 2.84 cfs @ 12.35 hrs, Volume= 0.349 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Reach 20CP: Control Point - Bridge St Drainage System Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Outflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Reach 40CP: Control Point Inflow = 0.90 cfs @ 12.25 hrs, Volume= 0.100 of Outflow = 0.90 cfs @ 12.25 hrs, Volume= 0.100 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Pond 1 B: Existing Depression Inflow = 0.67 cfs @ 12.32 hrs, Volume= 0.114 of Outflow = 0.26 cfs @ 12.91 hrs, Volume= 0.112 af, Atten= 61 %, Lag= 35.5 min Discarded = 0.26 cfs @ 12.91 hrs, Volume= 0.112 of Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Routing by Stor -Ind method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Peak Elev= 286.06' Storage= 836 cf Plug -Flow detention time= 46.0 min calculated for 0.112 of (98% of inflow) Storage and wetted areas determined by Prismatic sections Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 285.25 41 0 0 286.00 1,674 643 643 287.00 5,080 3,377 4,020 287.50 7,670 3,188 7,208 287.75 12,050 2,465 9,673 • WHE Type 111 24 -hr Rainfall= 2.95" Prepared by The Berkshire Design Group, Inc. Page 9 HydroCADO 6.00 s/n 000752 © 1986 -2001 Applied Microcomputer Systems 1/10/2005 Discarded OutFlow (Free Discharge) L 2= Exfiltration Primary OutFlow (Free Discharge) ' =Broad-Crested Rectangular Weir # Routing Invert Outlet Devices 1 Primary 287.77' 50.0' long x 50.0' breadth Broad - Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63 2 Discarded 0.00' 0.008300 fpm Exfiltration over entire Surface area Pond 20B: West Basin Inflow = 7.47 cfs @ 12.17 hrs, Volume= 0.659 of Outflow = 0.67 cfs @ 13.73 hrs, Volume= 0.595 af, Atten= 91% Lag= 93.4 min Discarded = 0.67 cfs @ 13.73 hrs, Volume= 0.595 of Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Routing by Stor -Ind method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Peak Elev= 291.21' Storage= 13,663 cf Plug -Flow detention time= 233.0 min calculated for 0.595 of (90% of inflow) Storage and wetted areas determined by Prismatic sections Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 287.00 1,825 0 0 288.00 2,419 2,122 2,122 289.00 3,085 2,752 4,874 290.00 3,835 3,460 8,334 291.00 4,660 4,248 12,582 292.00 5,575 5,118 17,699 293.00 6,555 6,065 23,764 294.00 7,595 7,075 30,839 295.00 8,690 8,143 38,982 Qiscarded OutFlow (Free Discharge) 3= Exfiltration Primary OutFlow (Free Discharge) L Culvert 1= Orifice /Grate econdary OutFlow (Free Discharge) = Emergency Overflow Weir • WHE Type 111 24 -hr Rainfall = 2.95" Prepared by The Berkshire Design Group, Inc. Page 10 HydroCADO 6.00 s/n 000752 C 1986 -2001 Applied Microcomputer Systems 1/10/2005 # Routing Invert Outlet Devices 1 Device 2 292.00' 0.12' x 0.12' Horiz. Orifice /Grate X 72.00 Limited to weir flow C=0.600 2 Primary 288.00' 12.0" x 78.0' long Culvert RCP, square edge headwall, Ke= 0.500 Outlet Invert= 285.50' S= 0.0321 '/' n= 0.012 Cc= 0.900 3 Discarded 0.00' 0.008300 fpm Exfiltration over entire Surface area 4 Secondary 294.10' 15.0' long x 6.0' breadth Emergency Overflow Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 Coef. (English) 2.37 2.51 2.70 2.68 2.68 2.67 2.65 2.65 2.65 2.65 2.66 2.66 2. Pond 30B: East Basin Inflow = 7.78 cfs @ Outflow = 1.71 cfs @ Discarded = 1.71 cfs @ Primary = 0.00 cfs @ 12.41 hrs, Volume= 1.038 of 13.44 hrs, Volume= 1.037 af, 13.44 hrs, Volume= 1.037 of 0.00 hrs, Volume= 0.000 of Routing by Stor -Ind method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Atten= 78 %, Lag= 62.1 min Peak Elev= 286.57' Storage= 14,845 cf Plug -Flow detention time= 90.9 min calculated for 1.037 of (100% of inflow) Storage and wetted areas determined by Prismatic sections Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 285.00 5,810 0 0 286.00 10,025 7,918 7,918 287.00 14,095 12,060 19,978 288.00 56,350 35,223 55,200 288.50 67,400 30,938 86,138 Discarded OutFlow (Free Discharge) L3= Exfiltration Primary OutFlow (Free Discharge) t-1 =Culvert L2= Orifice /Grate _ # Routing Invert Outlet Devices 1 Primary 287.00' 12.0" x 100.0' long Culvert RCP, square edge headwall, Ke= 0.500 Outlet Invert= 286.00' S=0-01007' n=0.012 Cc= 0.900 2 Device 1 285.00' 0.12' x 0.12' Horiz. Orifice /Grate X 36.00 Limited to weir flow C=0.600 3 Discarded 0.00' 0.008300 fpm Exfiltration over entire Surface area • WHE Type l// 24 -hr Rainfall= 4.50" Prepared by The Berkshire Design Group, Inc. Page 11 HydroCADO 6.00 s/n 000752 C 1986 -2001 Applied Microcomputer Systems 1/10/2005 Time span =0.00 -24.00 hrs, dt =0.05 hrs, 481 points Runoff by SCS TR -20 method, UH =SCS, Type III 24 -hr Rainfall= 4.50" Reach routing by Stor- Ind +Trans method - Pond routing by Stor -Ind method Subcatchment 1 E: West Area Subcatchment 2E: West - Central Area Subcatchment 3E: East Central Area Subcatchment 4E: East Area Subcatchment 10P: West Area Subcatchment 20P: West - Central Area Subcatchment 30P: East - Central Area Subcatchment 31 P: Paved Roadway Subcatchment 40P: East Area Reach 1CP: Control Point Tc =25.7 min CN =71 Area =9.298 ac Runoff= 11.19 cfs 1.345 of Tc =10.8 min CN =60 Area =4.360 ac Runoff= 3.73 cfs 0.369 of Tc =27.3 min CN =62 Area = 11.948 ac Runoff= 8.35 cfs 1.126 of Tc =15.3 min CN =70 Area =1.752 ac Runoff= 2.48 cfs 0.244 of Tc =22.3 min CN =72 Area =5.406 ac Runoff= 7.25 cfs 0.816 of Tc =12.5 min CN =88 Area =4.470 ac Runoff= 13.28 cfs 1.188 of Tc =26.1 min CN =72 Area = 15.546 ac Runoff= 19.47 cfs 2.344 of Tc =5.0 min CN =98 Area =0.165 ac Runoff= 0.73 cfs 0.059 of Tc =15.3 min CN =70 Area =1.752 ac Runoff= 2.48 cfs 0.244 of Inflow= 11.19 cfs 1.345 of Outflow= 11.19 cfs 1.345 of Reach 1 R: Reach - Depression Overflow Path Inflow= 0.00 cfs 0.000 of Length= 260.0' Max Vel= 0.0 fps Capacity= 30.98 cfs Outflow= 0.00 cfs 0.000 of Reach 2CP: Control Point - Overflow to JFK P -Lot Inflow= 8.35 cfs 1.126 of Outflow= 8.35 cfs 1.126 of Reach 4CP: Control Point Inflow= 2.48 cfs 0.244 of Outflow= 2.48 cfs 0.244 of Reach 10CP: Control Point Inflow= 7.25 cfs 0.816 of Outflow= 7.25 cfs 0.816 of Reach 20CP: Control Point - Bridge St Drainage System Inflow= 1.55 cfs 0.201 of Outflow= 1.55 cfs 0.201 of • WHE Type 111 24 -hr Rainfall= 4.50" Prepared by The Berkshire Design Group, Inc. Page 12 HydroCADO 6.00 s/n 000752 © 1986 -2001 Applied Microcomputer Systems 1/10/2005 Reach 40CP: Control Point Inflow= 2.48 cfs 0.244 of Outflow= 2.48 cfs 0.244 of Pond 1 B: Existing Depression Peak Storage= 4,851 cf Inflow= 3.73 cfs 0.369 of Discarded= 0.80 cfs 0.363 of Primary= 0.00 cfs 0.000 of Outflow= 0.80 cfs 0.363 of Pond 20B: West Basin Peak Storage= 21,000 cf Inflow= 13.28 cfs 1.188 of Discarded= 0.84 cfs 0.774 of Primary= 3.68 cfs 0.253 of Secondary= 0.00 cfs 0.000 of Outflow= 4.53 cfs 1.027 of Pond 30B: East Basin Peak Storage= 43,494 cf Inflow= 22.86 cfs 2.655 of Discarded= 5.85 cfs 2.416 of Primary= 1.55 cfs 0.201 of Outflow= 7.40 cfs 2.617 of Runoff Area = 54.697 ac Volume = 7.734 of Average Depth = 1.70" M • WHE Type 111 24 -hr Rainfall= 4.50" Prepared by The Berkshire Design Group, Inc. Page 13 HydroCADO 6.00 s/n 000752 © 1986 -2001 Applied Microcomputer Systems 1/10/2005 Subcatchment 1 E: West Area Runoff = 11.19 cfs @ 12.38 hrs, Volume= 1.345 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 4.50" Area (ac) CN Description 0.260 74 >75% Grass cover, Good, HSG C 0.266 98 Roof and Paved Driveway 8.772 70 Woods, Good, HSG C 9.298 71 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) ( ft/ft) (ft/sec) (cfs) 16.0 100 0.0470 0.1 Sheet Flow, 4.360 60 Weighted Average Woods: Light underbrush n= 0.400 P2= 2.90" 5.3 365 0.0530 1.2 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 4.4 465 0.1230 1.8 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 25.7 930 Total Subcatchment 2E: West - Central Area Runoff = 3.73 cfs @ 12.17 hrs, Volume= 0.369 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 4.50" Are (ac) CN Description 0.089 98 Roofs 0.254 74 >75% Grass cover, Good, HSG C 2.129 70 Woods, Good, HSG C 1.668 39 >75% Grass cover, Good, HSG A 0.220 98 Pond 100 -yr Flood Elev 4.360 60 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.4 100 0.1000 0.3 Sheet Flow, Grass: Short n= 0.150 P2= 2.90" 2.7 430 0.1400 2.6 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 2.7 180 0.0250 1.1 Shallow Concentrated Flow, Short G rass Pasture Kv= 7.0 fps 10.8 710 Total • WHE Type 11124 -hr Rainfall= 4.50" Prepared by The Berkshire Design Group, Inc. Page 14 HydroCADO 6.00 s/n 000752 C 1986 -2001 Applied Microcomputer Systems 1/10/2005 Subcatchment 3E: East Central Area Runoff = 8.35 cfs @ 12.44 hrs, Volume= 1.126 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 4.50" Ar ea (ac) CN Description 0.105 98 Roofs 2.588 74 >75% Grass cover, Good, HSG C 5.832 70 Woods, Good, HSG C (ft/ft) 3.380 39 >75% Grass cover, Good, HSG A 0.043 30 Woods, Good HSG A Sheet Flow, 11.948 62 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) ( ft/ft) (ft/sec) (cfs) 14.9 100 0.0560 0.1 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 2.90" 4.2 450 0.1260 1.8 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 1.9 285 0.1260 2.5 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 6.3 300 0.0130 0.8 Shallow Concentrated Flow, Short G rass Pasture Kv= 7.0 fps 27.3 1,135 Total Subcatchment 4E: East Area Runoff = 2.48 cfs @ 12.22 hrs, Volume= 0.244 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 4.50" Ar ea (ac) CN Description 1.752 70 Woods, Good, HSG C Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.8 100 0.1000 0.1 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 2.90" 3.5 475 0.2000 2.2 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 15.3 575 Total 0 WHE Type 111 24 -hr Rainfall= 4.50" Prepared by The Berkshire Design Group, Inc. Page 15 HydroCADO 6.00 s/n 000752 C 1986 -2001 Applied Microcomputer Systems 1/10/2005 Subcatchment 10P: West Area Runoff = 7.25 cfs @ 12.32 hrs, Volume= 0.816 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 4.50" Area (ac) CN Description 4.308 70 Woods, Good, HSG C Roofs 0.783 74 >75% Grass cover, Good, HSG C 0.315 98 Roofs, Pavement 0.074 5.406 72 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 30 16.0 100 0.0470 0.1 Sheet Flow, 98 Pond at 100 -yr Peak Elev Woods: Light underbrush n= 0.400 P2= 2.90" 3.6 325 0.0910 1.5 Shallow Concentrated Flow, Tc Length Woodland Kv= 5.0 fps 1.7 187 0.1340 1.8 Shallow Concentrated Flow, (ft/ft) (ft/sec) (cfs) Woodland Kv= 5.0 fps 1.0 132 0.1890 2.2 Shallow Concentrated Flow, Woodland Kv= 5.0 fas 22.3 744 Total Subcatchment 20P: West - Central Area Runoff = 13.28 cfs @ 12.17 hrs, Volume= 1.188 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 4.50" Area (ac) CN Description 2.016 98 Roofs 1.736 74 >75% Grass cover, Good, HSG C 0.074 70 Woods, Good, HSG C 0.000 39 >75% Grass cover, Good, HSG A 0.017 30 Woods, Good, HSG A 0.627 98 Pond at 100 -yr Peak Elev 4.470 88 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.4 50 0.0250 0.2 Sheet Flow, Grass: Short n= 0.150 P2= 2.90" 2.1 255 0.0820 2.0 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 5.0 Direct Entrv. 12.5 305 Total • WHE Type 111 24 -hr Rainfall= 4.50" Prepared by The Berkshire Design Group, Inc. Page 16 HydroCADO 6.00 s/n 000752 © 1986 -2001 Applied Microcomputer Systems 1/10/2005 Subcatchment 30P: East - Central Area Runoff = 19.47 cfs @ 12.38 hrs, Volume= 2.344 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 4.50" Area (ac) CN Description 2.138 98 Roofs - Pavement 5.888 74 >75% Grass cover, Good, HSG C 2.675 70 Woods, Good, HSG C 3.113 39 >75% Grass cover, Good, HSG A 0.110 30 Woods, Good, HSG A 1.622 98 Pond at 100 -yr Peak Elev 15.546 72 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.8 100 0.1000 0.1 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 2.90" 4.5 460 0.1160 1.7 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 0.4 65 0.2660 2.6 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 4.3 440 0.1170 1.7 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 5.1 210 0.0190 0.7 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 26.1 1,275 Total Subcatchment 31 P: Paved Roadway Runoff = 0.73 cfs @ 12.07 hrs, Volume= 0.059 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 4.50" Ar ea (ac) CN Description 0.165 98 Pavement Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, • WHE Type 111 24 -hr Rainfall= 4.50" Prepared by The Berkshire Design Group, Inc. Page 17 HydroCADO 6.00 s/n 000752 C 1986 -2001 Applied Microcomputer Systems 1/10/2005 Subcatchment 40P: East Area Runoff = 2.48 cfs @ 12.22 hrs, Volume= 0.244 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 4.50" Area (ac) CN Description 1.752 70 Woods, Good, HSG C Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.8 100 0.1000 0.1 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 2.90" 3.5 475 0.2000 2.2 Shallow Concentrated Flow, Woodland Kv= 5.0 fqs 15.3 575 Total Reach 1CP: Control Point Inflow = 11.19 cfs @ 12.38 hrs, Volume= 1.345 of Outflow = 11.19 cfs @ 12.38 hrs, Volume= 1.345 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Reach 1 R: Reach - Depression Overflow Path Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Outflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Max. Velocity= 0.0 fps, Min. Travel Time= 0.0 min Avg. Velocity = 0.0 fps, Avg. Travel Time= 0.0 min Peak Depth= 0.00' Capacity at bank full= 30.98 cfs Inlet Invert= 287.75', Outlet Invert= 286.71' 100.00' x 0.25' deep channel, n= 0.030 Length= 260.0' Slope= 0.00407' Reach 2CP: Control Point - Overflow to JFK P -Lot Inflow = 8.35 cfs @ 12.44 hrs, Volume= 1.126 of Outflow = 8.35 cfs @ 12.44 hrs, Volume= 1.126 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs • WHE Type 111 24 -hr Rainfall= 4.50" Prepared by The Berkshire Design Group, Inc. Page 18 HydroCAD® 6.00 s/n 000752 © 1986 -2001 Applied Microcomputer Systems 1/10/2005 Reach 4CP: Control Point Inflow = 2.48 cfs @ 12.22 hrs, Volume= 0.244 of Outflow = 2.48 cfs @ 12.22 hrs, Volume= 0.244 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Reach 10CP: Control Point Inflow = 7.25 cfs @ 12.32 hrs, Volume= 0.816 of Outflow = 7.25 cfs @ 12.32 hrs, Volume= 0.816 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Reach 20CP: Control Point - Bridge St Drainage System Inflow = 1.55 cfs @ 13.06 hrs, Volume= 0.201 of Outflow = 1.55 cfs @ 13.06 hrs, Volume= 0.201 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Reach 40CP: Control Point Inflow = 2.48 cfs @ 12.22 hrs, Volume= 0.244 of Outflow = 2.48 cfs @ 12.22 hrs, Volume= 0.244 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Routing by Stor -Ind method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Peak Elev= 287.13' Storage= 4,851 cf Plug -Flow detention time= 80.1 min calculated for 0.363 of (98% of inflow) Storage and wetted areas determined by Prismatic sections Elevation (feet) Surf.Area (sq -ft) Pond 1B: Existing Depression Inflow = 3.73 cfs @ 12.17 hrs, Volume= 0.369 of Outflow = 0.80 cfs @ 12.87 hrs, Volume= 0.363 af, Atten= 79 %, Lag= 42.0 min Discarded = 0.80 cfs @ 12.87 hrs, Volume= 0.363 of Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Routing by Stor -Ind method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Peak Elev= 287.13' Storage= 4,851 cf Plug -Flow detention time= 80.1 min calculated for 0.363 of (98% of inflow) Storage and wetted areas determined by Prismatic sections Elevation (feet) Surf.Area (sq -ft) Inc.Store (cubic -feet) Cum.Store (cubic -feet) 285.25 41 0 0 286.00 1,674 643 643 287.00 5,080 3,377 4,020 287.50 7,670 3,188 7,208 287.75 12,050 2,465 9,673 • WHE Type 111 24 -hr Rainfall= 4.50" Prepared by The Berkshire Design Group, Inc. Page 19 HydroCAD® 6.00 s/n 000752 © 1986 -2001 Applied Microcomputer Systems 1/10/2005 Discarded OutFlow (Free Discharge) L2= Exfiltration Primary OutFlow (Free Discharge) ' =Broad-Crested Rectangular Weir # Routing Invert Outlet Devices 1 Primary 287.77' 50.0' long x 50.0' breadth Broad - Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63 2 Discarded 0.00' 0.008300 fpm Exfiltration over entire Surface area Pond 20B: West Basin Inflow = 13.28 cfs @ 12.17 hrs, Volume= 1.188 of Outflow = 4.53 cfs @ 12.55 hrs, Volume= 1.027 af, Atten= 66 %, Lag= 22.8 min Discarded = 0.84 cfs @ 12.55 hrs, Volume= 0.774 of Primary = 3.68 cfs @ 12.55 hrs, Volume= 0.253 of Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Routing by Stor -Ind method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Peak Elev= 292.54' Storage= 21,000 cf Plug -Flow detention time= 192.0 min calculated for 1.025 of (86% of inflow) Storage and wetted areas determined by Prismatic sections Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 287.00 1,825 0 0 288.00 2,419 2,122 2,122 289.00 3,085 2,752 4,874 290.00 3,835 3,460 8,334 291.00 4,660 4,248 12,582 292.00 5,575 5,118 17,699 293.00 6,555 6,065 23,764 294.00 7,595 7,075 30,839 295.00 8,690 8,143 38,982 Discarded OutFlow (Free Discharge) L3= Exfiltration Primary OutFlow (Free Discharge) L2= Culvert L1= Orifice /Grate econdary OutFlow (Free Discharge) = Emergency Overflow Weir • WHE Type 111 24 -hr Rainfall= 4.50" Prepared by The Berkshire Design Group, Inc. Page 20 HydroCAD® 6.00 s/n 000752 © 1986 -2001 Applied Microcomputer Systems 1/10/2005 # Routinq Invert Outlet Devices 1 Device 2 292.00' 0.12' x 0.12' Horiz. Orifice /Grate X 72.00 Limited to weir flow C=0.600 2 Primary 288.00' 12.0" x 78.0' long Culvert RCP, square edge headwall, Ke= 0.500 Primary = 1.55 cfs @ Outlet Invert= 285.50' S= 0.0321 '/' n= 0.012 Cc= 0.900 3 Discarded 0.00' 0.008300 fpm Exfiltration over entire Surface area 4 Secondary 294.10' 15.0' long x 6.0' breadth Emergency Overflow Weir 7,918 287.00 Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 12,060 19,978 Coef. (English) 2.37 2.51 2.70 2.68 2.68 2.67 2.65 2.65 2.65 2.65 2.66 2.66 2 Pond 30B: East Basin Inflow = 22.86 cfs @ Outflow = 7.40 cfs @ Discarded = 5.85 cfs @ Primary = 1.55 cfs @ 12.40 hrs, Volume= 2.655 of 13.06 hrs, Volume= 2.617 af, 13.06 hrs, Volume= 2.416 of 13.06 hrs, Volume= 0.201 of Atten= 68 %, Lag= 39.6 min Routing by Stor -Ind method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Peak Elev= 287.67' Storage= 43,494 cf Plug -Flow detention time= 114.3 min calculated for 2.612 of (98% of inflow) Storage and wetted areas determined by Prismatic sections Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 285.00 5,810 0 0 286.00 10,025 7,918 7,918 287.00 14,095 12,060 19,978 288.00 56,350 35,223 55,200 288.50 67,400 30,938 86,138 Qiscarded OutFlow (Free Discharge) 3= Exfiltration Primary OutFlow (Free Discharge) t--1 =Culvert t- 2= Orifice /Grate # Routing Invert Outlet Devices 1 Primary 287.00' 12.0" x 100.0' long Culvert RCP, square edge headwall, Ke= 0.500 Outlet Invert= 286.00' S=0.0100'/' n=0.012 Cc= 0.900 2 Device 1 285.00' 0.12' x 0.12' Horiz. Orifice /Grate X 36.00 Limited to weir flow C=0.600 3 Discarded 0.00' 0.008300 fpm Exfiltration over entire Surface area • WHE Type 111 24 -hr Rainfall= 6.50" Prepared by The Berkshire Design Group, Inc. Page 21 HydroCAD® 6.00 s/n 000752 © 1986 -2001 Applied Microcomputer Systems 1/10/2005 Time span =0.00 -24.00 hrs, dt =0.05 hrs, 481 points Runoff by SCS TR -20 method, UH =SCS, Type III 24 -hr Rainfall= 6.50" Reach routing by Stor- Ind +Trans method - Pond routing by Stor -Ind method Subcatchment 1 E: West Area Tc =25.7 min CN =71 Area =9.298 ac Runoff= 21.75 cfs 2.549 of Subcatchment 2E: West - Central Area Tc =10.8 min CN =60 Area =4.360 ac Runoff= 9.32 cfs 0.818 of Subcatchment 3E: East Central Area Tc =27.3 min CN =62 Area = 11.948 ac Runoff= 19.48 cfs 2.413 of Subcatchment 4E: East Area Tc =15.3 min CN =70 Area =1.752 ac Runoff= 4.91 cfs 0.467 of Subcatchment 10P: West Area Tc =22.3 min CN =72 Area =5.406 ac Runoff= 13.86 cfs 1.528 of Subcatchment 20P: West - Central Area Tc =12.5 min CN =88 Area =4.470 ac Runoff= 20.80 cfs 1.900 of Subcatchment 30P: East - Central Area Tc =26.1 min CN =72 Area = 15.546 ac Runoff= 37.24 cfs 4.390 of Subcatchment 31 P: Paved Roadway Tc =5.0 min CN =98 Area =0.165 ac Runoff= 1.06 cfs 0.086 of Subcatchment 40P: East Area Tc =15.3 min CN =70 Area =1.752 ac Runoff= 4.91 cfs 0.467 of Reach 1CP: Control Point Inflow= 21.75 cfs 2.549 of Outflow= 21.75 cfs 2.549 of Reach 1 R: Reach - Depression Overflow Path Inflow= 0.00 cfs 0.000 of Length= 260.0' Max Vel= 0.0 fps Capacity= 30.98 cfs Outflow= 0.00 cfs 0.000 of Reach 2CP: Control Point - Overflow to JFK P -Lot Reach 4CP: Control Point Reach 10CP: Control Point Reach 20CP: Control Point - Bridge St Drainage System Inflow= 19.48 cfs 2.413 of Outflow= 19.48 cfs 2.413 of Inflow= 4.91 cfs 0.467 of Outflow= 4.91 cfs 0.467 of Inflow= 13.86 cfs 1.528 of Outflow= 13.86 cfs 1.528 of Inflow= 3.13 cfs 0.848 of Outflow= 3.13 cfs 0.848 of • WHE Type 111 24 -hr Rainfall= 6.50" Prepared by The Berkshire Design Group, Inc. Page 22 HydroCAD® 6.00 s/n 000752 © 1986 -2001 Applied Microcomputer Systems 1/10/2005 Reach 40CP: Control Point Inflow= 4.91 cfs 0.467 of Outflow= 4.91 cfs 0.467 of Pond 1B: Existing Depression Peak Storage= 12,200 cf Inflow= 9.32 cfs 0.818 of Discarded= 2.29 cfs 0.804 of Primary= 0.00 cfs 0.000 of Outflow= 2.29 cfs 0.804 of Pond 20B: West Basin Peak Storage= 31,024 cf Inflow= 20.80 cfs 1.900 of Discarded= 1.05 cfs 0.889 of Primary= 7.10 cfs 0.785 of Secondary= 0.00 cfs 0.000 of Outflow= 8.15 cfs 1.674 of Pond 30B: East Basin Peak Storage= 90,692 cf Inflow= 44.45 cfs 5.261 of Discarded= 9.55 cfs 4.223 of Primary= 3.13 cfs 0.848 of Outflow= 12.68 cfs 5.071 of Runoff Area = 54.697 ac Volume = 14.616 of Average Depth = 3.21" WHE Type 111 24 -hr Rainfall= 6.50" Prepared by The Berkshire Design Group, Inc. Page 23 HydroCADO 6.00 s/n 000752 © 1986 -2001 Applied Microcomputer Systems 1/10/2005 Subcatchment 1 E: West Area Runoff = 21.75 cfs @ 12.36 hrs, Volume= 2.549 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 6.50" Area (ac) CN Description 0.260 74 >75% Grass cover, Good, HSG C 0.266 98 Roof and Paved Driveway 8.77 70 Woods, Good, HSG C 9.298 71 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 16.0 100 0.0470 0.1 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 2.90" 5.3 365 0.0530 1.2 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 4.4 465 0.1230 1.8 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 25.7 930 Total Subcatchment 2E: West - Central Area Runoff = 9.32 cfs @ 12.16 hrs, Volume= 0.818 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 6.50" Area (ac) CN Description 0.089 98 Roofs 0.254 74 >75% Grass cover, Good, HSG C 2.129 70 Woods, Good, HSG C 1.668 39 >75% Grass cover, Good, HSG A 0.220 98 Pond 100 -yr Flood Elev 4.360 60 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) ( ft/sec) (cfs) 5.4 100 0.1000 0.3 Sheet Flow, Grass: Short n=0.150 P2=2.90" 2.7 430 0.1400 2.6 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 2.7 180 0.0250 1.1 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 10.8 710 Total • WHE Type 111 24 -hr Rainfall= 6.50" Prepared by The Berkshire Design Group, Inc. Page 24 HydroCADO 6.00 s/n 000752 © 1986 -2001 Applied Microcomputer Systems 1/10/2005 Subcatchment 3E: East Central Area Runoff = 19.48 cfs @ 12.40 hrs, Volume= 2.413 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 6.50" Area (ac) CN Description 0.105 98 Roofs 2.588 74 >75% Grass cover, Good, HSG C 5.832 70 Woods, Good, HSG C (ft/ft) 3.380 39 >75% Grass cover, Good, HSG A 0.043 30 Woods, Good, HSG A 0.1 11.948 62 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) Shallow Concentrated Flow, 14.9 100 0.0560 0.1 Sheet Flow, Woodland Kv= 5.0 fps Woods: Light underbrush n= 0.400 P2= 2.90" 4.2 450 0.1260 1.8 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 1.9 285 0.1260 2.5 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 6.3 300 0.0130 0.8 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 27.3 1,135 Total Subcatchment 4E: East Area Runoff = 4.91 cfs @ 12.22 hrs, Volume= 0.467 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 6.50" Area (ac) CN Description 1.752 70 Woods, Good, HSG C Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.8 100 0.1000 0.1 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 2.90" 3.5 475 0.2000 2.2 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 15.3 575 Total • WHE Type 111 24 -hr Rainfall= 6.50" Prepared by The Berkshire Design Group, Inc. Page 25 HydroCADO 6.00 s/n 000752 © 1986 -2001 Applied Microcomputer Systems 1/10/2005 Subcatchment 10P: West Area Runoff = 13.86 cfs @ 12.31 hrs, Volume= 1.528 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 6.50" Area (ac) CN Description 4.308 70 Woods, Good, HSG C 0.783 74 >75% Grass cover, Good, HSG C 0.315 98 Roofs, Pavement 5.406 72 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/f0 (ft/sec) (cfs) 16.0 100 0.0470 0.1 Sheet Flow, 0.627 98 Pond at 100 -yr Peak Elev 4.470 Woods: Light underbrush n= 0.400 P2= 2.90" 3.6 325 0.0910 1.5 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 1.7 187 0.1340 1.8 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 1.0 132 0.1890 2.2 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 22.3 744 Total Subcatchment 20P: West - Central Area Runoff = 20.80 cfs @ 12.17 hrs, Volume= 1.900 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 6.50" Area (ac) CN Description 2.016 98 Roofs 1.736 74 >75% Grass cover, Good, HSG C 0.074 70 Woods, Good, HSG C 0.000 39 >75% Grass cover, Good, HSG A 0.017 30 Woods, Good, HSG A 0.627 98 Pond at 100 -yr Peak Elev 4.470 88 Weighted Average Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 5.4 50 0.0250 0.2 Sheet Flow, Grass: Short n=0.150 P2=2.90" 2.1 255 0.0820 2.0 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 5.0 Direct Entrv. 12.5 305 Total • WHE Type 111 24 -hr Rainfall= 6.50" Prepared by The Berkshire Design Group, Inc. Page 26 HydroCADO 6.00 s/n 000752 © 1986 -2001 Applied Microcomputer Systems 1/10/2005 Subcatchment 30P: East - Central Area Runoff = 37.24 cfs @ 12.37 hrs, Volume= 4.390 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 6.50" Area (ac) CN Description 2.138 98 Roofs - Pavement 5.888 74 >75% Grass cover, Good, HSG C 2.675 70 Woods, Good, HSG C 3.113 39 >75% Grass cover, Good, HSG A 0.110 30 Woods, Good, HSG A 1.622 98 Pond at 100 -yr Peak Elev 15.546 72 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/f0 (ft/sec) (cfs) 11.8 100 0.1000 0.1 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 2.90" 4.5 460 0.1160 1.7 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 0.4 65 0.2660 2.6 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 4.3 440 0.1170 1.7 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 5.1 210 0.0190 0.7 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 26.1 1,275 Total Subcatchment 31P: Paved Roadway Runoff = 1.06 cfs @ 12.07 hrs, Volume= 0.086 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 6.50" Area (ac) CN Description 0.165 98 Pavement Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, WHE Type 111 24 -hr Rainfall= 6.50" Prepared by The Berkshire Design Group, Inc. Page 27 HydroCADO 6.00 s/n 000752 © 1986 -2001 Applied Microcomputer Systems 1/10/2005 Subcatchment 40P: East Area Runoff = 4.91 cfs @ 12.22 hrs, Volume= 0.467 of Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type III 24 -hr Rainfall= 6.50" Area (ac) CN Descriotion 1.752 70 Woods, Good, HSG C Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.8 100 0.1000 0.1 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 2.90" 3.5 475 0.2000 2.2 Shallow Concentrated Flow, Woodland Kv= 5.0 fqs 15.3 575 Total Reach 1 CP: Control Point Inflow = 21.75 cfs @ 12.36 hrs, Volume= 2.549 of Outflow = 21.75 cfs @ 12.36 hrs, Volume= 2.549 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Reach 1 R: Reach - Depression Overflow Path Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Outflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Max. Velocity= 0.0 fps, Min. Travel Time= 0.0 min Avg. Velocity = 0.0 fps, Avg. Travel Time= 0.0 min Peak Depth= 0.00' Capacity at bank full= 30.98 cfs Inlet Invert= 287.75', Outlet Invert= 286.71' 100.00' x 0.25' deep channel, n= 0.030 Length= 260.0' Slope= 0.00407' Reach 2CP: Control Point - Overflow to JFK P -Lot Inflow = 19.48 cfs @ 12.40 hrs, Volume= 2.413 of Outflow = 19.48 cfs @ 12.40 hrs, Volume= 2.413 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs WHE Type 111 24 -hr Rainfall= 6.50" Prepared by The Berkshire Design Group, Inc. Page 28 HydroCAD& 6.00 s/n 000752 © 1986 -2001 Applied Microcomputer Systems 1/10/2005 Reach 4CP: Control Point Inflow = 4.91 cfs @ 12.22 hrs, Volume= 0.467 of Outflow = 4.91 cfs @ 12.22 hrs, Volume= 0.467 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Reach 10CP: Control Point Inflow = 13.86 cfs @ 12.31 hrs, Volume= 1.528 of Outflow = 13.86 cfs @ 12.31 hrs, Volume= 1.528 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Reach 20CP: Control Point - Bridge St Drainage System Inflow = 3.13 cfs @ 13.18 hrs, Volume= 0.848 of Outflow = 3.13 cfs @ 13.18 hrs, Volume= 0.848 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Reach 40CP: Control Point Inflow = 4.91 cfs @ 12.22 hrs, Volume= 0.467 of Outflow = 4.91 cfs @ 12.22 hrs, Volume= 0.467 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Routing by Stor -Ind method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Peak Elev= 288.01' Storage= 12,200 cf Plug -Flow detention time= 92.0 min calculated for 0.802 of (98% of inflow) Storage and wetted areas determined by Prismatic sections Elevation (feet) Surf.Area (sq -ft) Pond 1B: Existing Depression Inflow = 9.32 cfs @ 12.16 hrs, Volume= 0.818 of Outflow = 2.29 cfs @ 12.66 hrs, Volume= 0.804 af, Atten= 75 %, Lag= 30.0 min Discarded = 2.29 cfs @ 12.66 hrs, Volume= 0.804 of Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Routing by Stor -Ind method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Peak Elev= 288.01' Storage= 12,200 cf Plug -Flow detention time= 92.0 min calculated for 0.802 of (98% of inflow) Storage and wetted areas determined by Prismatic sections Elevation (feet) Surf.Area (sq -ft) Inc.Store (cubic -feet) Cum.Store (cubic -feet) 285.25 41 0 0 286.00 1,674 643 643 287.00 5,080 3,377 4,020 287.50 7,670 3,188 7,208 287.75 12,050 2,465 9,673 • WHE Type 11124 -hr Rainfall= 6.50" Prepared by The Berkshire Design Group, Inc. Page 29 HydroCAD& 6.00 s/n 000752 © 1986 -2001 Applied Microcomputer Systems 1/10/2005 Qiscarded OutFlow (Free Discharge) 2= Exfiltration Primary OutFlow (Free Discharge) t--1 =Broad-Crested Rectangular Weir # Routing Invert Outlet Devices 1 Primary 287.77' 50.0' long x 50.0' breadth Broad - Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63 2 Discarded 0.00' 0.008300 fpm Exfiltration over entire Surface area Pond 20B: West Basin Inflow = 20.80 cfs @ 12.17 hrs, Volume= 1.900 of Outflow = 8.15 cfs @ 12.50 hrs, Volume= 1.674 af, Atten= 61 %, Lag= 20.0 min Discarded = 1.05 cfs @ 12.50 hrs, Volume= 0.889 of Primary = 7.10 cfs @ 12.50 hrs, Volume= 0.785 of Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Routing by Stor -Ind method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Peak Elev= 294.02' Storage= 31,024 cf Plug -Flow detention time= 140.9 min calculated for 1.674 of (88% of inflow) Storage and wetted areas determined by Prismatic sections Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 287.00 1,825 0 0 288.00 2,419 2,122 2,122 289.00 3,085 2,752 4,874 290.00 3,835 3,460 8,334 291.00 4,660 4,248 12,582 292.00 5,575 5,118 17,699 293.00 6,555 6,065 23,764 294.00 7,595 7,075 30,839 295.00 8,690 8,143 38,982 Discarded OutFlow (Free Discharge) t-3= Exfiltration Primary OutFlow (Free Discharge) t-Mlvert t--1 =Orifice/Grate Secondary OutFlow (Free Discharge) t -4= Emergency Overflow Weir • WHE Type 111 24 -hr Rainfall= 6.50" Prepared by The Berkshire Design Group, Inc. Page 30 HydroCAD& 6.00 s/n 000752 © 1986 -2001 Applied Microcomputer Systems 1/10/2005 # Routinq Invert Outlet Devices 1 Device 2 292.00' 0.12' x 0.12' Horiz. Orifice /Grate X 72.00 Limited to weir flow C=0.600 2 Primary 288.00' 12.0" x 78.0' long Culvert RCP, square edge headwall, Ke= 0.500 Primary = 3.13 cfs @ Outlet Invert= 285.50' S= 0.0321 '/' n= 0.012 Cc= 0.900 3 Discarded 0.00' 0.008300 fpm Exfiltration over entire Surface area 4 Secondary 294.10' 15.0' long x 6.0' breadth Emergency Overflow Weir 7,918 287.00 Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 12,060 19,978 Coef. (English) 2.37 2.51 2.70 2.68 2.68 2.67 2.65 2.65 2.65 2.65 2.66 2.66 2 Pond 30B: East Basin Inflow = 44.45 cfs @ Outflow = 12.68 cfs @ Discarded = 9.55 cfs @ Primary = 3.13 cfs @ 12.37 hrs, Volume= 5.261 of 13.18 hrs, Volume= 5.071 af, 13.18 hrs, Volume= 4.223 of 13.18 hrs, Volume= 0.848 of Atten= 71 %, Lag= 48.7 min Routing by Stor -Ind method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Peak Elev= 288.57' Storage= 90,692 cf Plug -Flow detention time= 109.9 min calculated for 5.060 of (96% of inflow) Storage and wetted areas determined by Prismatic sections Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 285.00 5,810 0 0 286.00 10,025 7,918 7,918 287.00 14,095 12,060 19,978 288.00 56,350 35,223 55,200 288.50 67,400 30,938 86,138 Qiscarded OutFlow (Free Discharge) 3= Exfiltration Primary OutFlow (Free Discharge) t-1 Ivert t- 2= Orifice /G rate # Routing Invert Outlet Devices 1 Primary 287.00' 12.0" x 100.0' long Culvert RCP, square edge headwall, Ke= 0.500 Outlet Invert= 286.00' S=0.0100'/' n=0.012 Cc= 0.900 2 Device 1 285.00' 0.12' x 0.12' Horiz. Orifice /Grate X 36.00 Limited to weir flow C=0.600 3 Discarded 0.00' 0.008300 fpm Exfiltration over entire Surface area M