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HomeMy WebLinkAboutAsbuilt Storm Water Management Plan Asbuilt Storm Water Management Plan Calculations & Summaries SPIENSA DEV. GROUP Orono, MN Project No. 11586 June 18, 2009 Revised October 29, 2009 — Calculations for asbuilt survey of pond size and grouted riprap overflow Prepared By: Prepared For: Anderson Engineering of Minnesota, LLC Spensa Dev Group 13605 15'Avenue North, Suite 100 Minnetonka, MN 55305 Plymouth, MN 55441 Ph. 763 412-4000 Fax 763 412-4090 ASBUILT STORM WATER MANAGEMENT PLAN SPENSA DEY GROUP Orono, MN Comm. No. 11586 June 18, 2009 Revised October 29, 2009— Calculations for asbuilt survey of pond size and grouted riprap overflow I hereby certify that this plan, specification or report was prepared by me or under my direct supervision and that I am a duly Licensed Professional Engineer under the laws of the State of Minnesota. Michael B. Brandvold, P.E. Reg. No. 41258 October 29, 2009 Prepared By: Prepared For: Anderson Engineering of Minnesota, LLC Spensa Dev Group, LLC 13605 1St Avenue North, Suite 100 Minnetonka MN 55305 Plymouth, MN 55441 Ph. (763) 412-4000 Fax (763) 412-4090 Spensa Dev. Group Proj No. 11586 2687 Wayzata Blvd, Orono, MN Storm Water Runoff Analysis* October 29, 2009 Volume Discharge Summary (Acre-FT) ac-ft ac-ft 2-(2.8" 0.16 0.05 10-(4.2') 0.29 0.16 100-(6.0') 0.45 0.31 Rate Discharge Summary (Cu. Ft. per Second) s���itQT/l? ilbf TeteTeV9e `sltl. cfs cfs 2-(2.8') 2.74 0.50 10-(4.2') 4.68 2.55 100-(6.0') 7.17 6.21 *Runoff design criteria based on City approvals of maintaining or decreasing water runoff volumes and rates leaving the southeasterly area of site. *Rain garden overflow spillway constructed of grouted rip rap. 5 ft wide by 2 ft in depth. High Water Level Summary ae$tgri storm �ti �$�1 siren :-err). ?�pT�ap 'J/�err 2-(2.6') 1021.2 10-(4.2') 1021.5 100-(6.0') 1021.7 ZADocs 11 500\1 1586 Orono Bldg-Spensa\DRAINAGE\6-17-09 SWMP\10-28-09 RUNOFF Comparison riprap.xlsx X:\11500\11586 Spensa CronoNdwg\old\EXlST COND DRAINAGE.dwg,1:50 ---------------- ---------- - ------------ I.-S. 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Sueur'6 ��; Le Su®ur B q r• 4�.a t3�{� f mit a n i 'Y Y aE _ 1i CDrdova'I BID O fil ' E a Dundas Co BID a 0 U 7; 1 Le Sueur B ` } 1 t cli at Lerdat=to CID Anderson Engineering of Minnesota,LLC C I V[L ENG I N E E R 1 N G AND LAND SURVEYING (/,,�A �t Spensa Development Group, LLC o 116115 ter AV 611 UE 3)412-4 SUITE 100.PLm-40TII,SIH Slial �j� P �V 2687 Wayzata Blvd,Orono,Minnesota Feet TEL(rol al=.area r,'x nnl ar.-aru 1"= 100' 11� 6--- o.,TableDesign Hyc�rotogtc� '� 4 _"k. 5oi!Grou �IncFtesl Sotl Txt<tres ''Ggfresponcttng �ttied Soal Glass cation holrj =>{ GW-Well-graded gravels, sandy gravels Gravel, sandy gravel and GP — Gap-graded or uniform gravels, sandy 1.63 silty gravels gravels A GM-Silty gravels,silty sandy gravels SW-Well-graded, gravelly sands 0.8 Sand, loamy sand or sandy SP - Gap-graded or uniform sands, gravelly loam sands d 0.6 Silt loam SM-Silty sands, silty gravelly sands �I B 0.3 Loam MH -- Micaceous silts, diatomaceous silts, volcanic ash C 0.2 Sandy clay loam ML-Silts, very fine sands, silty or clayey fine sands GC—Clayey gravels, clayey sandy gravels SC—Clayey sands, clayey gravelly sands D <0.2 Clay loam, silty clay loam, CL—Low plasticity clays, sandy or silty clays sandy clay,silty clay or clay OL—Organic silts and clays of low plasticity CH—Highly plastic clays and sandy clays OH—Organic silts and clays of high plasticity *Thirty guidance manuals and many other stormwater references were reviewed to compile recommended infiltration rates. All of these sources use the following studies as the basis for their recommended infiltration rates: Rawls, Brakensiek and Saxton(1982);Rawls, Gimenez and Grossman(1998);Bouwer and Rice (1989);and Urban Hydrology for Small Watersheds(NRCS). The rates presented in this infiltration table use the information compiled from these sources as well as eight years of infiltration rates collected in various infiltration practices located in the Twin Cities metropolitan area. p levels of runoff. Care must also be taken when numbers appropriate to AMC II. However, if the i1 selecting curve numbers for agricultural land as its specific conditions of interest are expected to use can change considerably annually and even differ, curve numbers appropriate to AMC I or III over the course of a season. should be used. fAntecedent Moisture Conditions Antecedent moisture conditions (AMC) describe Infiltration Rates the moisture already present in the soil at the Infiltration is the process of water entering the time of the rain event. AMC level I represents dry soil matrix. The rate of infiltration depends on conditions, level II represents normal conditions, soil properties, vegetation, and the slope of the and level III represents wet conditions. Normal surface, among other factors. Discussions of conditions are defined as 1.4 to 2.1 inches of infiltration often include a discussion of hydraulic rainfall in the growing season in the five days conductivity. Hydraulic conductivity is a measure preceding the event of interest. Most evaluations of ease with which a fluid flows through the soil, of expected future site conditions use the curve but it is not the infiltration rate. The infiltration rate 2X 1X 2P 1P EXISTIN EXISTI G PROPO ED PROPO ED RAIN G POND 1 Q-exist Q-asbuiit Q (existing) Q (asbuilt) Subcat Reach on Link Drainage Diagram for 11586 SPENSA-ORONO-revised 10-28-09 Grout Riprap Prepared by Anderson Engineering of MN LLC 10/29/2009 HydroCADS 8.00 s/n 000837 0 2006 HydroCAD Software Solutions LLC Z:\HydroCAD\HCDATA\MBB\ As Built 11586 SPENSA-ORONO -revised 10-28-09 Grout Riprap Type 1124-hr 2 yr Rainfall=2.80" Prepared by Anderson Engineering of MN LLC Page 2 HydroCAD®8.00 s/n 000837 0 2006 HydroCAD Software Solutions LLC 10/29/2009 Subcatchment 1 P: PROPOSED Runoff = 2.41 cfs @ 12.01 hrs, Volume= 0.134 af, Depth= 1.64" Runoff by SCS TR-20 method, UH=SCS, Time Span=4.00-27.00 hrs, dt= 0.05 hrs Type II 24-hr 2 yr Rainfall=2.80" Area (sf) CN Description 1,590 61 >75% Grass cover, Good, HSG B 190 61 >75% Grass cover, Good, HSG B 6,420 61 >75% Grass cover, Good, HSG B 7,240 85 Gravel roads, HSG B 580 85 Gravel roads, HSG B 20,460 98 Paved parking& roofs 6,060 98 Building 42,540 88 Weighted Average 16,020 Pervious Area 26,520 Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Typical Inspection Subcatchment 1X: EXISTING Runoff = 2.27 cfs @ 12.04 hrs, Volume= 0.134 af, Depth= 1.64" Runoff by SCS TR-20 method, UH=SCS, Time Span= 4.00-27.00 hrs, dt= 0.05 hrs Type II 24-hr 2 yr Rainfall=2.80" Area (sf) CN Description 1,590 61 >75% Grass cover, Good, HSG B 2,340 61 >75% Grass cover, Good, HSG B 7,240 85 Gravel roads, HSG B 13,600 85 Gravel roads, HSG B 11,760 98 Paved parking & roofs 6,060 98 Building 42,590 88 Weighted Average 24,770 Pervious Area 17,820 Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 12.0 Direct Entry,Typical Inspection Z:1HydroCAD1HCDATAIMBBI As Built 11586 SPENSA -ORONO -revised 10-28-09 Grout Riprap Type //24-hr 2 yr Rainfall=2.80" Prepared by Anderson Engineering of MN LLC Page 3 HydroCADO 8.00 s/n 000837 ©2006 HydroCAD Software Solutions LLC 10/29/2009 Subcatchment 213: PROPOSED Runoff = 0.50 cfs @ 12.02 hrs, Volume= 0.032 af, Depth> 2.54" Runoff by SCS TR-20 method, UH=SCS, Time Span=4.00-27.00 hrs, dt=0.05 hrs Type II 24-hr 2 yr Rainfall=2.80" Area (sf) CN Description 6,630 98 Paved parking & roofs 6,630 Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.0 Direct Entry,Typical Inspection Subcatchment 2X: EXISTING Runoff = 0.47 cfs @ 12.03 hrs, Volume= 0.030 af, Depth> 2.35" Runoff by SCS TR-20 method, UH=SCS, Time Span=4.00-27.00 hrs, dt= 0.05 hrs Type II 24-hr 2 yr Rainfall=2.80" Area (sf) CN Description 1,140 85 Gravel roads, HSG B 5,490 98 Paved parking & roofs 6,630 96 Weighted Average 1,140 Pervious Area 5,490 Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 12.0 Direct Entry,Typical Inspection Reach Q -exist: Q (existing) Inflow Area = 1.130 ac, Inflow Depth > 1.74" for 2 yr event Inflow = 2.74 cfs @ 12.04 hrs, Volume= 0.164 of Outflow = 2.74 cfs @ 12.04 hrs, Volume= 0.164 af, Atten=0%, Lag= 0.0 min Routing by Star-Ind+Trans method, Time Span=4.00-27.00 hrs, dt= 0.05 hrs Reach Q-asbuilt: Q (asbuilt) Inflow Area = 1.129 ac, Inflow Depth > 0.48" for 2 yr event Inflow = 0.50 cfs @ 12.02 hrs, Volume= 0.045 of Outflow = 0.50 cfs @ 12.02 hrs, Volume= 0.045 af, Atten=0%, Lag= 0.0 min Z:\HydroCAD\HCDATA\MBB\ As Built 11586 SPENSA- ORONO -revised 10-28-09 Grout Riprap Type 1124-hr 2 yr Rainfall=2.80" Prepared by Anderson Engineering of MN LLC Page 4 HydroCAD®8.00 sh 000837 ©2006 HydroCAD Software Solutions LLC 10/29/2009 Routing by Stor-Ind+Trans method, Time Span=4.00-27.00 hrs, dt= 0.05 hrs Pond RAIN G: POND 1 Inflow Area = 0.977 ac, Inflow Depth = 1.64" for 2 yr event Inflow = 2.41 cfs @ 12.01 hrs, Volume= 0.134 of Outflow = 0.12 cfs @ 13.48 hrs, Volume= 0.071 af, Atten= 95%, Lag= 88.0 min Discarded = 0.04 cfs @ 13.48 hrs, Volume= 0.058 of Primary = 0.07 cfs @ 13.48 hrs, Volume= 0.013 of Routing by Stor-Ind method, Time Span=4.00-27.00 hrs, dt= 0.05 hrs Peak Elev= 1,021.23' @ 13.48 hrs Surf.Area= 3,225 sf Storage= 3,527 cf Plug-Flow detention time= 376.7 min calculated for 0.071 of(53% of inflow) Center-of-Mass det. time= 261.4 min ( 1,082.7- 821.3) Volume Invert Avail.Storage Storage Description #1 1,019.50' 8,590 cf Custom Stage Data(Prismatic) Listed below(Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 1,019.50 751 0 0 1,020.00 1,546 574 574 1,021.00 2,937 2,242 2,816 1,022.00 4,187 3,562 6,378 1,022.50 4,660 2,212 8,590 Device Routing Invert Outlet Devices #1 Discarded 0.00' 0.600 in/hr Exfiltration over Horizontal area #2 Primary 1,021.20' 5.0' long x 2.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 Qiscarded OutFlow Max=0.04 cfs @ 13.48 hrs HW=1,021.23' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.04 cfs) Primary OutFlow Max=0.07 cfs @ 13.48 hrs HW=1,021.23' (Free Discharge) L2=13road-Crested Rectangular Weir (Weir Controls 0.07 cfs @ 0.44 fps) Z:1HydroCADIHCDATAIMBB\ As Built 11586 SPENSA- ORONO -revised 10-28-09 Grout Riprap Type 1124-hr 10 yr Rainfall=4.20" Prepared by Anderson Engineering of MN LLC Page 5 HydroCAD®8.00 s/n 000837 ©2006 HydroCAD Software Solutions LLC 10/29/2009 Subcatchment 1 P: PROPOSED Runoff = 4.20 cfs @ 12.01 hrs, Volume= 0.237 af, Depth= 2.92" Runoff by SCS TR-20 method, UH=SCS, Time Span=4.00-27.00 hrs, dt= 0.05 hrs Type II 24-hr 10 yr Rainfall=4.20" Area (so CN Description 1,590 61 >75% Grass cover, Good, HSG B 190 61 >75% Grass cover, Good, HSG B 6,420 61 >75% Grass cover, Good, HSG B 7,240 85 Gravel roads, HSG B 580 85 Gravel roads, HSG B 20,460 98 Paved parking & roofs 6,060 98 Building 42,540 88 Weighted Average 16,020 Pervious Area 26,520 Impervious Area Tc Length Slope Velocity Capacity Description min feet ft/ft ft/sec cfs 10.0 Direct Entry,Typical Inspection Subcatchment 1X: EXISTING Runoff = 3.95 cfs @ 12.04 hrs, Volume= 0.238 af, Depth= 2.92" Runoff by SCS TR-20 method, UH=SCS, Time Span=4.00-27.00 hrs, dt= 0.05 hrs Type II 24-hr 10 yr Rainfall=4.20" Area (sf) CN Description 1,590 61 >75% Grass cover, Good, HSG B 2,340 61 >75% Grass cover, Good, HSG B 7,240 85 Gravel roads, HSG B 13,600 85 Gravel roads, HSG B 11,760 98 Paved parking & roofs 6,060 98 Building 42,590 88 Weighted Average 24,770 Pervious Area 17,820 Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 12.0 Direct Entry,Typical Inspection Z:1HydroCAD1HCDATAIMBBI As Built 11586 SPENSA - ORONO -revised 10-28-09 Grout Riprap Type 1124-hr 10 yr Rainfall=4.20" Prepared by Anderson Engineering of MN LLC Page 6 HydroCADO 8.00 s/n 000837 ©2006 HydroCAD Software Solutions LLC 10/29/2009 Subcatchment 2P: PROPOSED Runoff = 0.76 cfs @ 12.02 hrs, Volume= 0.049 af, Depth> 3.90" Runoff by SCS TR-20 method, UH=SCS, Time Span=4.00-27.00 hrs, dt= 0.05 hrs Type II 24-hr 10 yr Rainfall=4.20" Area (so CN Description 6,630 98 Paved parking & roofs 6,630 Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.0 Direct Entry,Typical Inspection Subcatchment 2X: EXISTING Runoff = 0.73 cfs @ 12.03 hrs, Volume= 0.047 af, Depth> 3.72" Runoff by SCS TR-20 method, UH=SCS, Time Span=4.00-27.00 hrs, dt= 0.05 hrs Type II 24-hr 10 yr Rainfall=4.20" Area (so CN Description 1,140 85 Gravel roads, HSG B 5,490 98 Paved parking & roofs 6,630 96 Weighted Average 1,140 Pervious Area 5,490 Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 12.0 Direct Entry, Typical Inspection Reach Q -exist: Q (existing) Inflow Area = 1.130 ac, Inflow Depth > 3.02" for 10 yr event Inflow = 4.68 cfs @ 12.03 hrs, Volume= 0.285 of Outflow = 4.68 cfs @ 12.03 hrs, Volume= 0.285 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span=4.00-27.00 hrs, dt= 0.05 hrs Reach Q-asbuilt: Q (asbuilt) Inflow Area = 1.129 ac, Inflow Depth > 1.65" for 10 yr event Inflow = 2.55 cfs @ 12.12 hrs, Volume= 0.156 of Outflow = 2.55 cfs @ 12.12 hrs, Volume= 0.156 af, Atten= 0%, Lag= 0.0 min Z:\HydroCAD\HCDATA\MBB\ As Built 11586 SPENSA - ORONO -revised 10-28-09 Grout Riprap Type 1124-hr 10 yr Rainfall=4.20" Prepared by Anderson Engineering of MN LLC Page 7 HydroCADO 8.00 s/n 000837 ©2006 HydroCAD Software Solutions LLC 10/29/2009 Routing by Stor-Ind+Trans method, Time Span=4.00-27.00 hrs, dt= 0.05 hrs Pond RAIN G: POND 1 Inflow Area = 0.977 ac, Inflow Depth = 2.92" for 10 yr event Inflow = 4.20 cfs @ 12.01 hrs, Volume= 0.237 of Outflow = 2,11 cfs @ 12.14 hrs, Volume= 0.169 af, Atten= 50%, Lag= 8.0 min Discarded = 0.05 cfs @ 12.14 hrs, Volume= 0.063 of Primary = 2.06 cfs @ 12.14 hrs, Volume= 0.106 of Routing by Stor-Ind method, Time Span=4.00-27.00 hrs, dt=0.05 hrs Peak Elev= 1,021.50' @ 12.14 hrs Surf.Area= 3,556 sf Storage=4,423 cf Plug-Flow detention time=204.2 min calculated for 0.169 of(71% of inflow) Center-of-Mass def. time= 107.9 min ( 912.9- 804.9) Volume Invert Avail.Storage Storage Description #1 1,019.50' 8,590 cf Custom Stage Data (Prismatic) Listed below(Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 1,019.50 751 0 0 1,020.00 1,546 574 574 1,021.00 2,937 2,242 2,816 1,022.00 4,187 3,562 6,378 1,022.50 4,660 2,212 8,590 Device Routing Invert Outlet Devices #1 Discarded 0.00' 0.600 in/hr Exfiltration over Horizontal area #2 Primary 1,021.20' 5.0' long x 2.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 Discarded OutFlow Max=0.05 cfs @ 12.14 hrs HW=1,021.49' (Free Discharge) t-1=Exfiltration (Exfiltration Controls 0.05 cfs) Primary OutFlow Max=2.04 cfs @ 12.14 hrs HW=1,021.49' (Free Discharge) 't2=Broad-Crested Rectangular Weir (Weir Controls 2.04 cfs @ 1.39 fps) Z:\HydroCAD\HCDATA\MBB\ As Built 11586 SPENSA- ORONO -revised 10-28-09 Grout Riprap Type 1124-hr 100 yr Rainfaii=6.00" Prepared by Anderson Engineering of MN LLC Page 8 HydroCAD®8,00 sh 000837 ©2006 HydroCAD Software Solutions LLC 10/29/2009 Subcatchment 1 P: PROPOSED Runoff - 6.50 cfs @ 12.01 hrs, Volume= 0.376 af, Depth> 4.63" Runoff by SCS TR-20 method, UH=SCS, Time Span=4.00-27.00 hrs, dt= 0.05 hrs Type II 24-hr 100 yr Rainfall=6.00" Area (sf) CN Description 1,590 61 >75% Grass cover, Good, HSG B 190 61 >75% Grass cover, Good, HSG B 6,420 61 >75% Grass cover, Good, HSG B 7,240 85 Gravel roads, HSG B 580 85 Gravel roads, HSG B 20,460 98 Paved parking & roofs 6,060 98 Building 42,540 88 Weighted Average 16,020 Pervious Area 26,520 Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Typical Inspection Subcatchment 1X: EXISTING Runoff = 6.12 cfs @ 12.03 hrs, Volume= 0.377 af, Depth> 4.63" Runoff by SCS TR-20 method, UH=SCS, Time Span=4.00-27.00 hrs, dt= 0.05 hrs Type II 24-hr 100 yr Rainfall=6.00" Area (sf) CN Description 1,590 61 >75% Grass cover, Good, HSG B 2,340 61 >75% Grass cover, Good, HSG B 7,240 85 Gravel roads, HSG B 13,600 85 Gravel roads, HSG B 11,760 98 Paved parking &roofs 6,060 98 Building _ 42,590 88 Weighted Average 24,770 Pervious Area 17,820 Impervious Area Tc Length Slope Velocity Capacity Description _ min) (feet) (ft/ft) (ft/sec) (cfs) 12.0 Direct Entry, Typical Inspection Z:\HydroCAD\HCDATA\MBB\ As Built 11586 SPENSA - ORONO -revised 10-28-09 Grout Riprap Type 11 24-hr 900 yr Rainfall=6.00" Prepared by Anderson Engineering of MN LLC Page 9 HydroCADO 8.00 s/n 000837 ©2006 HydroCAD Software Solutions LLC 10/29/2009 Subcatchment 2P: PROPOSED Runoff = 1.10 cfs @ 12.02 hrs, Volume= 0.072 af, Depth> 5.64" Runoff by SCS TR-20 method, UH=SCS, Time Span=4.00-27.00 hrs, dt= 0.05 hrs Type II 24-hr 100 yr Rainfall=6.00" Area (sf) CN Description 6,630 98 Paved parking & roofs 6,630 Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.0 Direct Entry, Typical Inspection Subcatchment 2X: EXISTING Runoff = 1.05 cfs @ 12.03 hrs, Volume= 0.069 af, Depth> 5.47" Runoff by SCS TR-20 method, UH=SCS, Time Span=4.00-27.00 hrs, dt= 0.05 hrs Type II 24-hr 100 yr Rainfall=6.00" Area (so CN Description 1,140 85 Gravel roads, HSG B 5,490 98 Paved parking & roofs 6,630 96 Weighted Average 1,140 Pervious Area 5,490 Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 12.0 Direct Entry, Typical Inspection Reach Q -exist: Q (existing) Inflow Area = 1.130 ac, Inflow Depth > 4.74" for 100 yr event Inflow = 7.17 cfs @ 12.03 hrs, Volume= 0.446 of Outflow = 7.17 cfs @ 12.03 hrs, Volume= 0.446 af, Atten= 0%, Lag=0.0 min Routing by Stor-Ind+Trans method, Time Span=4.00-27.00 hrs, dt= 0.05 hrs Reach Q-asbuilt: Q (asbuilt) Inflow Area = 1.129 ac, Inflow Depth > 3.31" for 100 yr event Inflow = 6.21 cfs @ 12.07 hrs, Volume= 0.312 of Outflow = 6.21 cfs @ 12.07 hrs, Volume= 0.312 af, Atten= 0%, Lag= 0.0 min Z:1HydroCAD1HCDATAIMBBI As Built 11586 SPENSA - ORONO -revised 10-28-09 Grout Riprap Type 1124-hr 900 yr Rainfall=6.00" Prepared by Anderson Engineering of MN LLC Page 10 HydroCAD®8.00 s/n 000837 ©2006 HydroCAD Software Solutions LLC 10/29/2009 Routing by Stor-Ind+Trans method, Time Span=4.00-27.00 hrs, dt= 0.05 hrs Pond RAIN G: POND 1 Inflow Area = 0.977 ac, Inflow Depth > 4.63" for 100 yr event Inflow = 6.50 cfs @ 12.01 hrs, Volume= 0.376 of Outflow = 5.26 cfs @ 12.08 hrs, Volume= 0.307 af, Atten= 19%, Lag=4.0 min Discarded = 0.05 cfs @ 12.08 hrs, Volume= 0.067 of Primary = 5.21 cfs @ 12.08 hrs, Volume= 0.240 of Routing by Stor-Ind method, Time Span=4.00-27.00 hrs, dt= 0.05 hrs Peak Elev= 1,021.74' @ 12.08 hrs Surf.Area= 3,864 sf Storage= 5,339 cf Plug-Flow detention time= 146.3 min calculated for 0.307 of(82% of inflow) Center-of-Mass det. time= 69.7 min ( 861.6- 792.0) Volume Invert Avail.Storage Storage Description #1 1,019.50' 8,590 cf Custom Stage Data(Prismatic) Listed below(Recalc) Elevation Surf.Area Inc.Store Cum,Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 1,019.50 751 0 0 1,020.00 1,546 574 574 1,021.00 2,937 2,242 2,816 1,022.00 4,187 3,562 6,378 1,022.50 4,660 2,212 8,590 Device Routing Invert Outlet Devices #1 Discarded 0.00' 0.600 in/hr Exfiltration over Horizontal area #2 Primary 1,021.20' 5.0' long x 2.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 Discarded OutFlow Max=0.05 cfs @ 12.08 hrs HW=1,021.73' (Free Discharge) t-1=Exfiltration (Exfiltration Controls 0.05 cfs) Primary OutFlow Max=5.10 cfs @ 12.08 hrs HW=1,021.73' (Free Discharge) t--2=13road-Crested Rectangular Weir (Weir Controls 5.10 cfs @ 1.91 fps) Wayzata Blvd �x 6� 0 x E 0 r y 0 14 f7 Globe", 1:5000, 0.6m V== 80' Anderson Engineering of Minnesota,LLC Spensa Development Group, LLC o 40 ao �t CIVIL ENGINEERING AND LAND SURVEYING Feet otos 1.1 Arrnulc noun,w1rE uo.rwwooru,sln sol 2687 Wayzata Blvd, Orono, Minnesota TEL nu/us-u..TAX(1631 411-401. Oct 14,2009 8JH