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Stormwater Management Report 4 STORMWATER ANALYSIS REPORT For a Proposed Single Family Residence Prepared for: David & Lois Arakelian 14 Trout Pavillion Rd Pilot Knob Tax Map # 227.10-1-27 Towns of Queensbury & Fort Ann Warren & Washington County New York Prepared by: G. Thomas Hutchins, P.E. Hutchins Engineering 169 Haviland Road Queensbury, NY 12804 January 3, 2008 Revised: April 14, 2008 Project Description This project consists of the teardown of two existing cottages and the construction of a new single family residence with an attached garage and an asphalt driveway. The project also involves the construction of associated stormwater and erosion controls and landscaping on a 3.61 acre lot owned by David & Lois Arakelian, located on the Trout Pavilion Road on Lake George in the Towns of Fort Ann and Queensbury. Approximately 3.1 acres of the parcel is located in the Town of Queensbury and the remainder is located in the Town of Fort Ann. Site Conditions The lot presently contains two cabins, a tennis court and associated landscaping which serves as seasonal residences for the Arakelian family. Vegetation on the lot is primarily dense, well landscaped grass and shrubs with several large trees. A large intermittent stream which crosses Pilot Knob Road through a 6' wide box culvert is located near the southerly property line. The site slopes westerly to the lake at an average grade of 8-12%. Site soils are mapped as Bice-Woodstock very bouldery fine sandy loams and Oakville loamy fine sand. A soil test pit which was conducted in the area of the proposed wastewater absorption field revealed 39"± of cobbly, silty sand and gravelly sand over silty, clayey loam. Drainacie Methodology & Stormwater Management Practices For projects in the Lake George drainage basin, the Town of Queensbury requires that there will be no increase in runoff volume from a 10-year design storm and no increase in runoff rate from a 25-year design storm in predeveloped vs. developed site conditions. Presently there are no significant stormwater control measures on the site. The project amounts to an increase in impervious area of approximately 2200 SF, with the house and garage being constructed in approximately the same location as the existing cabins. A new 882 SF driveway will be constructed, as there is presently not a driveway on the property. Runoff from the house and garage roofs will be captured in gutters and piped to a retention area which is to be located on the east side of the garage. The new driveway will be cross pitched to allow the runoff to sheet flow to the retention area. The proposed retention area will be grass lined with select plantings and will have a 635 SF footprint with a 1-1.5 foot average depth. A 4' wide rip-rap lined outlet is to be provided on the southeast end of the retention area, which will serve as an overflow during spring melting conditions and extreme storms. In order to capture runoff from the proposed patio area between the house and driveway, a 2'x2'x18' stone filled infiltration trench is proposed along the west side of this patio. No infiltration or volume credit is taken for this trench in the stormwater model. Runoff calculations have been prepared utilizing SCS TR-20 methodology and HydroCAD analysis software for 10-year and 25-year Type II simulated rainfall distributions. Criteria utilized in the analysis are summarized as follows: Design Storm Events: 10 year, 24hr, Type II distribution, 3.9" 25 year, 24hr, Type II distribution, 4.4" Infiltration Rate: 1" per hour Total Lot Area: 157,132 SF (3.61 Acres) Existing Buildings: 1601 SF Proposed Buildings: 2645 SF Existing Driveways: 0 SF Proposed Driveways: 882 SF Proposed Patios: 271 SF Total Existing Impervious: 9934 SF Proposed Impervious: 12,131 SF Total Disturbed Area: 15,150 SF Runoff computations for undeveloped, existing and proposed conditions have been completed for 10-year and 25-year recurrence interval 24 hr storm events over the entire parcel area. Calculations are attached and are summarized as follows: TOTAL RUNOFF EXISTING — 10-YR 3.39 CFS / 0.315 AF PROPOSED — 10-YR 3.19 CFS / 0.303 AF EXISTING - 25-YR 4.90 CFS / 0.417 AF PROPOSED - 25-YR 4.75 CFS / 0.404 CF Full results of stormwater runoff computations are attached to this report. Results The analyses show that the proposed retention area is of adequate capacity to manage calculated runoff from the proposed construction without increasing peak calculated runoff rate or calculated runoff volume from the current conditions for 10- and 25-year design storms. Maintenance The vegetation in the retention area is to be trimmed and mowed as needed throughout the spring, summer and fall months. The rip-rap lined overflow outlet is to be inspected annually for any erosion or sediment accumulation and any corrective measures needed are to be taken. Roof gutters and associated piping are to be cleaned and flushed with water annually or as needed to remove siltation and leaf accumulations. Attachments HydroCAD Analysis for Type II 24 hr Rainfall = 3.9" (10 year) & 4.4" (25 year) 10-Year Existing - 5 Pages Proposed - 6 Pages 25-Year Existing - 5 Pages Proposed - 6 Pages EXISTING °4, 4,0 � g aOa s kz It big R�6E t "•�. Z a � Q Y M a N 44 t � � z_ T � 8tis V ra a 1 S ) 2S � 3S i j WESTERN P TION EASTERN POR ON T NIS COURT OF PROPE Y OF PROPER 1 L '', 1 R 4S RUNOFF TO LAKE ZISITREAM STREAM 2L SOUTHER 1Y RUNOFF 3L TOTAL SITE RUNOFF Subcat Reach. Pond Link Drainage Diagram for TROUT PAVILION EXISTING __- - Prepared by HUTCHINS ENGINEERING 4/15/2006 —J - - - HydroCADO 7.10 s/n 002373 ©2005 HydroCAD Software Solutions LLC TROUT PAVILION EXISTING Type 11 24-hr 10-YEAR Rainfall=3.90" Prepared by HUTCHINS ENGINEERING Page 2 HydroCAD®7 10 s/n 002373 ©2005 HydroCAD Software Solutions LLC 4/15/2008 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment IS: WESTERN PORTION OF PROPERTY Runoff Area=65,740 sf Runoff Depth>0.81" Flow Length=200' Tc=15.7 min CN=62 Runoff=1.31 cfs 0.102 of Subcatchment 2S: EASTERN PORTION OF PROPERTY Runoff Area=71,618 sf Runoff Depth>0.76" Flow Length=125' Tc=11.8 min CN=61 Runoff=1.53 cfs 0.104 of Subcatchment 3S: TENNIS COURT Runoff Area=8,333 sf Runoff Depth>3.66" Flow Length=100' Tc=4.7 min CN=98 Runoff=1.08 cfs 0.058 of Subcatchment 4S: STREAM Runoff Area=7,335 sf Runoff Depth>3.67" Flow Length=125' Tc=1.0 min CN=98 Runoff=1.03 cfs 0.051 of Reach 1R: STREAM Peak Depth=0.27' Max Vet=3.3 fps Inflow=2.62 cfs 0,214 of n=0.040 L=125.0' S=0.0800 7 Capacity=194.71 cfs Outflow=2.57 cfs 0.214 of Link 1 L: RUNOFF TO LAKE Inflow=1.31 cfs 0.102 of Primary=1.31 cfs 0.102 of Link 2L: SOUTHERLY RUNOFF Inflow=3.39 cfs 0.315 of Primary=3.39 cfs 0.315 of Link 3L: TOTAL SITE RUNOFF Inflow=3.39 cfs 0.315 of Primary=3.39 cfs 0.315 of Total Runoff Area = 3.513 ac Runoff Volume = 0.315 of Average Runoff Depth = 1.08" TROUT PAVILION EXISTING Type 1124-hr 10-YEAR Rainfall=3.90" Prepared by HUTCHINS ENGINEERING Page 3 HydroCADO 7.10 s/n 002373 @ 2005 HydroCAD Software Solutions LLC 4/15/2008 Subcatchment 1S: WESTERN PORTION OF PROPERTY Runoff = 1.31 cfs @ 12.10 hrs, Volume= 0.102 af, Depth> 0.81" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 10-YEAR Rainfall=3.90" Area (sf) CN Description 64,835 61 >75% Grass cover, Good, HSG B 905 98 CABIN 65,740 62 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (f/ft) (f/sec) (cfs) 15.7 200 0.1000 0.2 Sheet Flow, Grass: Dense n= 0.240 P2= 2.20" Subcatchment 2S: EASTERN PORTION OF PROPERTY Runoff = 1.53 cfs @ 12.06 hrs, Volume= 0.104 af, Depth> 0.76" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 10-YEAR Rainfall=3.90" Area (sf) CN Description 70,915 61 >75% Grass cover, Good, HSG B 703 98 CABIN 71,618 61 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (f/ft) (ft/sec) (cfs) 11.8 125 0.0800 0.2 Sheet Flow, Grass: Dense n= 0.240 P2= 2.20" Subcatchment 3S: TENNIS COURT Runoff = 1.08 cfs @ 11.95 hrs, Volume= 0.058 af, Depth> 3.66" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 10-YEAR Rainfall=3.90" Area (sf) CN Description 8,333 98 TENNIS COURT TROUT PAVILION EXISTING Type 1124-hr 10-YEAR Rainfall=3.90" Prepared by HUTCHINS ENGINEERING Page 4 HydroCADS 7 10 s/n 002373 ©2005 HydroCAD Software Solutions LLC 4/15/2008 Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.3 75 0.0150 1.0 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.20" 3.4 25 0.0700 0.1 Sheet Flow, Grass: Dense n= 0.240 P2= 2.20" 4.7 100 Total Subcatchment 4S: STREAM Runoff = 1.03 cfs @ 11.90 hrs, Volume= 0.051 af, Depth> 3.67" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 10-YEAR Rainfall=3.90" Area (sf) CN Description 7,335 98 STREAM Tc Length Slope Velocity Capacity Description (min) (feet) (fUft) (f/sec) (cfs) 1.0 125 0.0800 2.1 49.62 Channel Flow, STREAM BED Area= 24.0 sf Perim= 275.0' r- 0.09' n= 0.040 Earth, cobble bottom, clean sides Reach 1 R: STREAM Inflow Area = 2.004 ac, Inflow Depth > 1.28" for 10-YEAR event Inflow = 2.62 cfs @ 11.96 hrs, Volume= 0.214 of Outflow = 2.57 cfs @ 11.97 hrs, Volume= 0.214 af, Atten= 2%, Lag= 1.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 3.3 fps, Min. Travel Time= 0.6 min Avg. Velocity = 1.1 fps, Avg. Travel Time= 1.9 min Peak Depth= 0.27' @ 11.96 hrs Capacity at bank full= 194.71 cfs Inlet Invert= 210.00', Outlet Invert= 200.00' 12.00' x 2.00' deep Parabolic Channel, n= 0.040 Earth, cobble bottom, clean sides Length= 125.0' Slope= 0.0800 T Link 1L: RUNOFF TO LAKE Inflow Area = 1.509 ac, Inflow Depth > 0.81" for 10-YEAR event Inflow = 1.31 cfs @ 12,10 hrs, Volume= 0.102 of Primary = 1.31 cfs @ 12.10 hrs, Volume= 0.102 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs TROUT PAVILION EXISTING Type 1124-hr 10-YEAR Rainfall=3.90" Prepared by HUTCHINS ENGINEERING Page 5 HydroCAD®7.10 s/n 002373 @ 2005 HydroCAD Software Solutions LLC 4/15/2008 Link 2L: SOUTHERLY RUNOFF Inflow Area = 3.513 ac, Inflow Depth > 1.08" for 10-YEAR event Inflow = 3.39 cfs @ 12.04 hrs, Volume= 0.315 of Primary = 3.39 cfs @ 12.04 hrs, Volume= 0.315 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link 3L: TOTAL SITE RUNOFF Inflow Area = 3.513 ac, Inflow Depth > 1.08" for 10-YEAR event Inflow = 3.39 cfs @ 12.04 hrs, Volume= 0.315 of Primary = 3.39 cfs @ 12.04 hrs, Volume= 0.315 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs TROUT PAVILION EXISTING Type 11 24-hr 25-YEAR Rainfall=4.50" Prepared by HUTCHINS ENGINEERING Page 6 HydroCAD®7 10 s/n 002373 ©2005 HydroCAD Software Solutions LLC 4/15/2008 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: WESTERN PORTION OF PROPERTY Runoff Area=65,740 sf Runoff Depth>1.13" Flow Length=200' Tc=15.7 min CN=62 Runoff=1.96 cfs 0.143 of Subcatchment 2S: EASTERN PORTION OF PROPERTY Runoff Area=71,618 sf Runoff Depth>1.07" Flow Length=125' Tc=11.8 min CN=61 Runoff=2.32 cfs 0.147 of Subcatchment 3S: TENNIS COURT Runoff Area=8,333 sf Runoff Depth>4.26" Flow Length=100' Tc=4.7 min CN=98 Runoff=1.25 cfs 0.068 of Subcatchment 4S: STREAM Runoff Area=7,335 sf Runoff Depth>4.26" Flow Length=125' Tc=1.0 min CN=98 Runoff=1.19 cfs 0.060 of Reach 1 R: STREAM Peak Depth=0.31' Max Vet=3.6 fps Inflow=3.49 cfs 0.275 of n=0.040 L=125.0' S=0.0800 '/' Capacity=194.71 cfs Outflow=3.41 cfs 0.275af Link 1L: RUNOFF TO LAKE Inflow=1.96 cfs 0.143 of Primary=1.96 cfs 0.143 of Link 2L: SOUTHERLY RUNOFF Inflow=4.90 cfs 0.417 of Primary=4.90 cfs 0.417 of Link 3L: TOTAL SITE RUNOFF Inflow=4.90 cfs 0.417 of Primary=4.90 cfs 0.417 of Total Runoff Area = 3.513 ac Runoff Volume = 0.418 of Average Runoff Depth = 1.43" TROUT PAVILION EXISTING Type If 24-hr25-YEAR Rainfall=4.50" Prepared by HUTCHINS ENGINEERING Page 7 HydroCADO 7.10 s/n 002373 ©2005 HydroCAD Software Solutions LLC 4/15/2008 Subcatchment 1S: WESTERN PORTION OF PROPERTY Runoff = 1.96 cfs @ 12.10 hrs, Volume= 0.143 af, Depth> 1.13" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0,00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 25-YEAR Rainfall=4.50" Area (sf) CN Description 64,835 61 >75% Grass cover, Good, HSG B 905 98 CABIN 65,740 62 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ftlft) (ft/sec) (cfs) 15.7 200 0.1000 0.2 Sheet Flow, Grass: Dense n= 0.240 P2= 2.20" Subcatchment 2S: EASTERN PORTION OF PROPERTY Runoff = 2.32 cfs @ 12.05 hrs, Volume= 0.147 af, Depth> 1.07" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 25-YEAR Rainfall=4.50" Area (sf) CN Description 70,915 61 >75% Grass cover, Good, HSG B 703 98 CABIN 71,618 61 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.8 125 0.0800 0.2 Sheet Flow, Grass: Dense n= 0.240 P2= 2.20" Subcatchment 3S: TENNIS COURT Runoff = 1.25 cfs @ 11.95 hrs, Volume= 0.068 af, Depth> 4.26" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 25-YEAR Rainfall=4.50" Area (sf) CN Description 8,333 98 TENNIS COURT TROUT PAVILION EXISTING Type Il 24-hr 25-YEAR Rainf611=4.50" Prepared by HUTCHINS ENGINEERING Page 8 HydroCAD®7 10 s/n 002373 ©2005 HydroCAD Software Solutions LLC 4/15/2008 Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.3 75 0.0150 1.0 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.20" 3.4 25 0,0700 0.1 Sheet Flow, Grass: Dense n= 0.240 P2= 2.20" 4.7 100 Total Subcatchment 4S: STREAM Runoff = 1.19 cfs @ 11.90 hrs, Volume= 0.060 af, Depth> 4.26" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 25-YEAR Rainfall=4.50" Area (sf) CN Description 7,335 98 STREAM Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.0 125 0.0800 2.1 49.62 Channel Flow, STREAM BED Area=24.0 sf Perim= 275.0' r= 0.09' n= 0.040 Earth, cobble bottom, clean sides Reach 1R: STREAM Inflow Area = 2.004 ac, Inflow Depth > 1.65" for 25-YEAR event Inflow = 3.49 cfs @ 11.96 hrs, Volume= 0.275 of Outflow = 3.41 cfs @ 11.98 hrs, Volume= 0.275 af, Atten= 2%, Lag= 1.2 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 3.6 fps, Min. Travel Time=0.6 min Avg. Velocity= 1.1 fps, Avg. Travel Time= 1.8 min Peak Depth= 0.31' @ 11.97 hrs Capacity at bank full= 194.71 cfs Inlet Invert= 210.00', Outlet Invert= 200.00' 12.00' x 2.00' deep Parabolic Channel, n= 0.040 Earth, cobble bottom, clean sides Length= 125.0' Slope= 0.0800 T Link 1L: RUNOFF TO LAKE Inflow Area = 1.509 ac, Inflow Depth > 1.13" for 25-YEAR event Inflow = 1.96 cfs @ 12.10 hrs, Volume= 0.143 of Primary = 1.96 cfs @ 12.10 hrs, Volume= 0.143 af, Atten= 0%, Lag= 0.0 min Primary outflow= Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs PROPOSED s % | Z � e-2 � ■ % ,��� / � � , \ 7 - / � . �■ � . � ® / »� | 1S 2S /> 3S - WESTERN ORTION EASTERN POR ON TENNI COURT i 4S� OFPROP RTY OF PROPER ZSTREAM 1L j [ 1R 5S RUNOFF TO LAKE ZXSTREA \ HOUSE &YARD 2L ! 1p SOUTHER RUNOFF RETENTION AREA 3L TOTAL SITE RUNOFF Suboat IReaoh Pond Link rainage Diagram for TROUT PAVILION PROPOSED R1 Prepared by HUTCHINS ENGINEERING 4/15/2008 FHyd'1oCADQ 7.10 s/n 002373 C 2005 HydroCAD Software Solutions LLC TROUT PAVILION PROPOSED R1 Type Il 24-hr 10-YEAR Rainfall=3.90" Prepared by HUTCHINS ENGINEERING Page 2 HydroCADO 7.10 s/n 002373 ©2005 HydroCAD Software Solutions LLC 4/15/2008 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1 S: WESTERN PORTION OF PROPERTY Runoff Area=62,845 sf Runoff Depth>0.76" Flow Length=200' Tc=15.7 min CN=61 Runoff=1.15 cfs 0,091 of Subcatchment 2S: EASTERN PORTION OF PROPERTY Runoff Area=69,250 sf Runoff Depth>0.76" Flow Length=125' Tc=11.8 min CN=61 Runoff=1.48 cfs 0.101 of Subcatchment 3S: TENNIS COURT Runoff Area=8,333 sf Runoff Depth>3.66" Flow Length=100' Tc=4.7 min CN=98 Runoff=1.08 cfs 0.058 of Subcatchment 4S: STREAM Runoff Area=7,335 sf Runoff Depth>3.67" Flow Length=125' Tc=1.0 min CN=98 Runoff=1.03 cfs 0.051 of Subcatchment 5S: HOUSE & YARD Runoff Area=5,280 sf Runoff Depth>2.12" Flow Length=45' Tc=3.4 min CN=82 Runoff=0.49 cfs 0.021 of Reach 1R: STREAM Peak Depth=0.27' Max Vet=3.3 fps Inflow=2.59 cfs 0.212 of n=0.040 L=125.0' S=0.0800 '/' Capacity=194.71 cfs Outflow=2.54 cfs 0.211 of Pond 1 P: RETENTION AREA Peak Elev=210.71' Storage=479 cf Inflow=0.49 cfs 0.021 of Discarded=0.01 cfs 0.013 of Primary=0.02 cfs 0.001 of Outflow=0.03 cfs 0.014 of Link 1L: RUNOFF TO LAKE Inflow=1.15 cfs 0,091 of Primary=1.15 cfs 0.091 of Link 2L: SOUTHERLY RUNOFF Inflow=3.19 cfs 0.303 of Primary=3.19 cfs 0.303 of Link 3L: TOTAL SITE RUNOFF Inflow=3.19 cfs 0.303 of Primary=3.19 cfs 0.303 of Total Runoff Area = 3.513 ac Runoff Volume = 0.323 of Average Runoff Depth = 1.10" TROUT PAVILION PROPOSED R1 Type 1124-hr 10-YEAR RainfallPage 3 Page 3 Prepared by HUTCHINS ENGINEERING 4/15/2008 H droCAD@ 7.10 s/n 002373 @ 2005 H droCAD Software Solutions LLC Subcatchment 1S: WESTERN PORTION OF PROPERTY Runoff = 1.15 cfs @ 12.11 hrs, Volume= 0.091 af, Depth> 0.76" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 10-YEAR Rainfall=3.90" Areas CN Description 62,814 61 >75% Grass cover, Good, HSG B 31 98 Patio 62,845 61 Weighted Average Tc Length Slope Velocity Capacity Description min feet fUft ft/sec cfs 15.7 200 0.1000 0.2 Sheet Flow, Grass: Dense n= 0.240 P2= 2.20" Subcatchment 2S: EASTERN PORTION OF PROPERTY Runoff = 1.48 cfs @ 12.06 hrs, Volume= 0.101 af, Depth> 0.76" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 10-YEAR Rainfall=3.90" Areas CN Description 68,425 61 >75% Grass cover, Good, HSG B 585 98 DRIVEWAY 240 98 PATIO 69,250 61 Weighted Average Tc Length Slope Velocity Capacity Description min feet fUft ft/sec cfs 11.8 125 0.0800 0.2 Sheet Flow, Grass: Dense n= 0.240 P2= 2.20" Subcatchment 3S: TENNIS COURT Runoff = 1.08 cfs @ 11.95 hrs, Volume= 0.058 af, Depth> 3.66" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 10-YEAR Rainfall=3.90" Area s CN Descri tion 8,333 98 TENNIS COURT 1 � TROUT PAVILION PROPOSED R1 Type 11 24-hr 10-YEAR Rainfall=3.90" Prepared by HUTCHINS ENGINEERING Page 4 HydroCAD®7 10 sin 002373 ©2005 HydroCAD Software Solutions LLC 4/15/2008 Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.3 75 0.0150 1.0 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.20" 3.4 25 0.0700 0.1 Sheet Flow, _ Grass: Dense n= 0.240 P2= 2.20" 4.7 100 Total Subcatchment 4S: STREAM Runoff = 1.03 cfs @ 11.90 hrs, Volume= 0.051 af, Depth> 3.67" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 10-YEAR Rainfall=3.90" Area (sf) CN Description 7,335 98 STREAM Tc Length Slope Velocity Capacity Description (min) (feet) (fUft) (ft/sec) (cfs) 1.0 125 0.0800 2.1 49.62 Channel Flow, STREAM BED Area= 24.0 sf Perim= 275.0' r- 0.09' n= 0.040 Earth, cobble bottom, clean sides Subcatchment 5S: HOUSE & YARD Runoff = 0.49 cfs @ 11.94 hrs, Volume= 0.021 af, Depth> 2.12" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 10-YEAR Rainfall=3.90" Area (sf) CN Description 300 98 Driveway 2,645 98 Paved parking & roofs 2,335 61 >75% Grass cover, Good HSG B 5,280 82 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.1 25 0.5000 3.1 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.20" 3.3 20 0.0500 0.1 Sheet Flow, Grass: Dense n= 0.240 P2= 2.20" 3A 45 Total , 6 TROUT PAVILION PROPOSED R1 Type 1124-hr 10-YEAR Rainfall=3.90" Prepared by HUTCHINS ENGINEERING Page 5 HydroCADO 7.10 s/n 002373 @ 2005 HydroCAD Software Solutions LLC 4/15/2008 Reach 1 R: STREAM Inflow Area = 2.071 ac, Inflow Depth > 1.23" for 10-YEAR event Inflow = 2.59 cfs @ 11.95 hrs, Volume= 0.212 of Outflow = 2.54 cfs @ 11.97 hrs, Volume= 0.211 af, Atten= 2%, Lag= 1.0 min Routing by Stor-Ind+Trans method, Time Span= 0,00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 3.3 fps, Min. Travel Time= 0.6 min Avg. Velocity = 1.1 fps, Avg. Travel Time= 1.9 min Peak Depth= 0.27' @ 11.96 hrs Capacity at bank full= 194.71 cfs Inlet Invert= 210.00', Outlet Invert= 200.00' 12.00' x 2.00' deep Parabolic Channel, n= 0.040 Earth, cobble bottom, clean sides Length= 125.0' Slope= 0.0800 T Pond 1P: RETENTION AREA Inflow Area = 0.121 ac, Inflow Depth > 2.12" for 10-YEAR event Inflow = 0.49 cfs @ 11.94 hrs, Volume= 0.021 of Outflow = 0.03 cfs @ 12.61 hrs, Volume= 0.014 af, Atten= 94%, Lag= 40.4 min Discarded = 0.01 cfs @ 12.61 hrs, Volume= 0.013 of Primary = 0.02 cfs @ 12.61 hrs, Volume= 0.001 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 210.71' @ 12.61 hrs Surf.Area= 554 sf Storage= 479 cf Plug-Flow detention time= 292.4 min calculated for 0.014 of (68% of inflow) Center-of-Mass det. time= 187.6 min ( 1,008.8 - 821.2 ) Volume Invert Avail.Storage Storage Description #1 209.50' 653 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 209.50 262 0 0 210.00 360 156 156 211.00 635 498 653 Device Routing Invert Outlet Devices #1 Primary 210.70' 8.0' long x 20.0' 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' 1.000 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.01 cfs @ 12.61 hrs HW=210.71' (Free Discharge) L2=Exfiltration (Exfiltration Controls 0.01 cfs) Primary OutFlow Max=0.01 cfs @ 12.61 hrs HW=210.71' (Free Discharge) L1=Broad-Crested Rectangular Weir (Weir Controls 0.01 cfs @ 0.2 fps) TROUT PAVILION PROPOSED R1 Type It 24-hr f0-YEAR Rainfall=3.90" Prepared by HUTCHINS ENGINEERING Page 6 HydroCAD® 7 10 s/n 002373 ©2005 HydroCAD Software Solutions LLC 4/15/2008 Link 1L: RUNOFF TO LAKE Inflow Area = 1.443 ac, Inflow Depth > 0.76" for 10-YEAR event Inflow = 1.15 cfs @ 12.11 hrs, Volume= 0.091 of Primary = 1.15 cfs @ 12.11 hrs, Volume= 0.091 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link 2L: SOUTHERLY RUNOFF Inflow Area = 3.513 ac, Inflow Depth > 1,03" for 10-YEAR event Inflow = 3.19 cfs @ 12.03 hrs, Volume= 0.303 of Primary = 3.19 cfs @ 12.03 hrs, Volume= 0.303 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link 3L: TOTAL SITE RUNOFF Inflow Area = 3.513 ac, Inflow Depth > 1.03" for 10-YEAR event Inflow = 3.19 cfs @ 12.03 hrs, Volume= 0.303 of Primary = 3.19 cfs @ 12.03 hrs, Volume= 0.303 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs TROUT PAVILION PROPOSED R1 Type Il 24-hr 25-YEAR Rainfall=4.50" Prepared by HUTCHINS ENGINEERING Page 7 HydroCAD®7.10 s/n 002373 ©2005 HydroCAD Software Solutions LLC 4/15/2008 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: WESTERN PORTION OF PROPERTY Runoff Area=62,845 sf Runoff Depth>1.07" Flow Length=200' Tc=15.7 min CN=61 Runoff=1.75 cfs 0.129 of Subcatchment 2S: EASTERN PORTION OF PROPERTY Runoff Area=69,250 sf Runoff Depth>1.07" Flow Length=125' Tc=11.8 min CN=61 Runoff=2.24 cfs 0.142 of Subcatchment 3S: TENNIS COURT Runoff Area=8,333 sf Runoff Depth>4.26" Flow Length=100' Tc=4.7 min CN=98 Runoff=1.25 cfs 0.068 of Subcatchment 4S: STREAM Runoff Area=7,335 sf Runoff Depth>4.26" Flow Length=125' Tc=1.0 min CN=98 Runoff=1.19 cfs 0.060 of Subcatchment 5S: HOUSE &YARD Runoff Area=5,280 sf Runoff Depth>2.63" Flow Length=45' Tc=3.4 min CN=82 Runoff=0.60 cfs 0.027 of Reach 1 R: STREAM Peak Depth=0.31' Max Vet=3.6 fps Inflow=3.44 cfs 0.275 of n=0.040 L=125.0' S=0.0800 '/' Capacity=194.71 cfs Outflow=3.34 cfs 0.275 of Pond 1P: RETENTION AREA Peak Elev=210.75' Storage=502 cf Inflow=0.60 cfs 0.027 of Discarded=0.01 cfs 0.014 of Primary=0.22 cfs 0.005 of Outflow=0.24 cfs 0.019 of Link 1 L: RUNOFF TO LAKE Inflow=1.75 cfs 0.129 of Primary=1.75 cfs 0.129 of Link 2L: SOUTHERLY RUNOFF Inflow=4.75 cfs 0.404 of Primary=4.75 cfs 0.404 of Link 3L: TOTAL SITE RUNOFF Inflow=4.75 cfs 0.404 of Primary=4.75 cfs 0.404 of Total Runoff Area = 3.513 ac Runoff Volume = 0.426 of Average Runoff Depth = 1.46" c � TROUT PAVILION PROPOSED R1 Type II 24-hr 25-YEAR Rainfall=4.50" Prepared by HUTCHINS ENGINEERING Page 8 HydroCADO 7.10 s/n 002373 ©2005 HydroCAD Software Solutions LLC 4/15/2008 Subcatchment 1S: WESTERN PORTION OF PROPERTY Runoff = 1.75 cfs @ 12.10 hrs, Volume-- 0.129 af, Depth> 1.07" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type It 24-hr 25-YEAR Rainfall=4.50" Area (sf) CN Description 62,814 61 >75% Grass cover, Good, HSG B 31 98 Patio 62,845 61 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (f/ft) (ft/sec) (cfs) 15.7 200 0.1000 0.2 Sheet Flow, Grass: Dense n= 0.240 P2= 2.20" Subcatchment 2S: EASTERN PORTION OF PROPERTY Runoff = 2.24 cfs @ 12.05 hrs, Volume= 0.142 af, Depth> 1.07" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 25-YEAR Rainfall=4.50" Area (sf) CN Description 68,425 61 >75% Grass cover, Good, HSG B 585 98 DRIVEWAY 240 98 PATIO 69,250 61 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.8 125 0.0800 0.2 Sheet Flow, Grass: Dense n= 0.240 P2= 2.20" Subcatchment 3S: TENNIS COURT Runoff = 1.25 cfs @ 11.95 hrs, Volume= 0.068 af, Depth> 4.26" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 25-YEAR Rainfall=4.50" Area (sf) CN Description 8,333 98 TENNIS COURT TROUT PAVILION PROPOSED R1 Type // 24-hr 25-YEAR Rainfall=4.50" Prepared by HUTCHINS ENGINEERING Page 9 HydroCAD®7.10 s/n 002373 ©2005 HydroCAD Software Solutions LLC 4/15/2008 Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.3 75 0.0150 1.0 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.20" 3.4 25 0.0700 0.1 Sheet Flow, Grass: Dense n= 0.240 P2= 2.20" 4.7 100 Total Subcatchment 4S: STREAM Runoff = 1.19 cfs @ 11.90 hrs, Volume= 0.060 af, Depth> 4.26" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type It 24-hr 25-YEAR Rainfall=4.50" Area (sf) CN Description 7,335 98 STREAM Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.0 125 0.0800 2.1 49.62 Channel Flow, STREAM BED Area= 24.0 sf Perim= 275.0' r= 0.09' n= 0.040 Earth, cobble bottom, clean sides Subcatchment 5S: HOUSE & YARD Runoff = 0.60 cfs @ 11.94 hrs, Volume= 0.027 af, Depth> 2.63" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 25-YEAR Rainfall=4.50" Area (sf) CN Description 300 98 Driveway 2,645 98 Paved parking & roofs 2,335 61 >75% Grass cover, Good, HSG B 5.280 82 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.1 25 0.5000 3.1 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.20" 3.3 20 0.0500 0.1 Sheet Flow, Grass: Dense n= 0.240 P2= 2,20" 3.4 45 Total TROUT PAVILION PROPOSED R1 Type 1124-hr 25-YEAR Rainfall=4.50" Prepared by HUTCHINS ENGINEERING Page 10 H droCADO 7.10 sin 002373 ©2005 H droCAD Software Solutions LLC 4/1 512 0 0 8 Reach 1 R: STREAM Inflow Area = 2.071 ac, Inflow Depth > 1.60" for 25-YEAR event Inflow = 3.44 cfs @ 11.96 hrs, Volume= 0.275 of Outflow = 3.34 cfs @ 11.99 hrs, Volume= 0,275 af, Atten= 3%, La g= 1.3 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24,00 hrs, dt= 0.05 hrs Max. Velocity= 3.6 fps, Min. Travel Time= 0.6 min Avg. Velocity = 1.1 fps, Avg. Travel Time= 1.8 min Peak Depth= 0.31' @ 11.97 hrs Capacity at bank full= 194.71 cfs Inlet Invert= 210.00', Outlet Invert= 200.00' 12.00' x 2.00' deep Parabolic Channel, n= 0,040 Earth, cobble bottom, clean sides Length= 125.0' Slope= 0.08007 Pond 1 P: RETENTION AREA Inflow Area = 0.121 ac, Inflow Depth > 2.63" for 25-YEAR event Inflow = 0.60 cfs @ 11.94 hrs, Volume= 0.027 of Outflow = 0.24 cfs @ 12.06 hrs, Volume= 0.019 af, Atten= 61%, Lag= 7.2 min Discarded = 0.01 cfs @ 12.06 hrs, Volume= 0.014 of Primary = 0.22 cfs @ 12.06 hrs, Volume= 0.005 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 210.75' @ 12.06 hrs Surf.Area= 566 sf Storage= 502 cf Plug-Flow detention time= 232.6 min calculated for 0.019 of (71% of inflow) Center-of-Mass det. time= 134.2 min ( 949.2 - 814.9 ) Volume Invert Avail Storage Storage Description #1 209.50' 653 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 209.50 262 0 0 210.00 360 156 156 211.00 635 498 653 Device Routing Invert Outlet Devices #1 Primary 210.70' 8.0' long x 20.0' 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' 1.000 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.01 cfs @ 12.06 hrs HW=210.74' (Free Discharge) L2=Exfiltration (Exfiltration Controls 0.01 cfs) Primary OutFlow Max=0.20 cfs @ 12.06 hrs HW=210.74' (Free Discharge) L1=Broad-Crested Rectangular Weir (Weir Controls 0.20 cfs @ 0.6 fps) b TROUT PAVILION PROPOSED R1 Type 1124-hr 25-YEAR Rainfall=4.50" Prepared by HUTCHINS ENGINEERING Page 11 HydroCAD®7.10 s/n 002373 ©2005 HydroCAD Software Solutions LLC 4/15/2008 Link 1L: RUNOFF TO LAKE Inflow Area = 1.443 ac, Inflow Depth > 1.07" for 25-YEAR event Inflow = 1.75 cfs @ 12.10 hrs, Volume= 0.129 of Primary = 1.75 cfs @ 12.10 hrs, Volume= 0.129 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link 2L: SOUTHERLY RUNOFF Inflow Area = 3.513 ac, Inflow Depth > 1.38" for 25-YEAR event Inflow = 4.75 cfs @ 12.05 hrs, Volume= 0.404 of Primary = 4.75 cfs @ 12.05 hrs, Volume= 0.404 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link 3L: TOTAL SITE RUNOFF Inflow Area = 3.513 ac, Inflow Depth > 1.38" for 25-YEAR event Inflow = 4.75 cfs @ 12.05 hrs, Volume= 0.404 of Primary = 4.75 cfs @ 12.05 hrs, Volume= 0.404 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs