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Storm Water Calcs 2-2-06 \. - Eme,rson Process Ma.nagement Chanhassen, Minnesota Storm Water Management Calculations CONTENTS o Storm Water Pond Design Memo o Hydrograph Return Period Recap o Hydrograph Summary Reports (2, 10, & 100 Year - 24 Hour Storms) o Hydrograph Reports for 100-Year Event o Reservoir Report o Pond Stage/Volume Data o Pond Outlet Structure Detail o Existing Drainage Area Map o Proposed Drainage Area Map It. CITY OF CHANHASSEN RECEIVED FEa 0 3 2006 Architecture I Engineering I Planning CHANHASSEN PLANNING OEPT Hammel, Green and Abrahamson, Inc. 701 Washington Avenue North Minneapolis, Minnesota 55401 (612) 758-4000 February 2,2006 HGA Commission Number: 1192-041-00 @ 2006 HGA, It. Architecture I Engineering I Planning Memorandum TO: FROM: Project File Erik A. Hansen \VRITER'S DIRECT DIAL (612) 758-4275 DATE: February 2,2006 SUBJECT: Emerson Process Management, Rosemount Inc. - Chanhassen Site Storm Water Pond Design HGA Commission Number 1192-041-00 Emerson Process Management, Rosemount Inc. proposes to construct an office building addition and associated parking adjacent to their current facility in Chanhassen, Minnesota. Storm water drainage from the site of the existing parking lot in the vicinity of the expansion is routed to a pond in the northeast corner of the site. The proposed storm water drainage from this area will be routed in two different directions. Storm water from the roof of the proposed addition and pervious area east of the existing parking will be routed to the existing pond (see attached drainage maps). The parking lot west of the existing building will be routed to the new storm water pond in the northwest portion of the site. This pond is sized to treat storm water from the proposed and future parking additions.-The storm water pond will discharge to the City of Chanhassen public storm sewer system via an existing 24" storm sewer stub located in Lake Drive. The proposed storm water basin will provide storage to reduce peak discharge rates, and provide the required wet volume for water quality treatment. A Riley Purgatory Bluff Creek Watershed District permit and MPCA General Storm-water Permit for Construction Activity are required for the proposed project. The storm water pond is designed to provide a minimum removal efficiency of: . 90% Total Suspended Solids (fSS) · 60% Total Phosphorus (fP) These requirements were then used in conjunction with Chapter 1 0, Volume 2 of the 2005 Minnesota Stormwater Manual. Version 1.0 to determine the pond design criteria. The following criteria were used: . Permanent Pool Volume (V pp) of 3,600 fe / ac of area draining to the pond. . Water Quality Volume (V w~ of 1.0 inch of runoff / ac of new site impervious. . Maximum discharge of 5.66 cfs/ surface acre of pond at the V wq elevation. This translates to a maximum discharge of 1.88cfs (5.66cfs/ac x 0.33 ac) for the 2-year rainfall event. Hammel, Green and Abrahamson, Inc_ 701 Washington Avenue North. Minneapolis, Minnesota USA 55401-1180 Telephone 612.758.4000 Facsimile 612.758.4199 Visit our Website: www.hga.com The proposed design includes: . A drainage area of 5.27 Ac. (4.0 ac Impervious) and a Curve Number of 90. . Permanent Pool Volume 01 pp) of 20,193 fe (3,832 fe / ac x 5.27 Ac) . Water Quality Volume 01w,) of 0.33 Ac-Ft (1" runoff x 4.0 ac). This results in a Vwq elevation of 929.7, or the equivalent of the 2-year rainfall event. . Maximum discharge of 1.76 cfs for the 2-year rainfall event. s:\1100\ 1192\041-00\work\civil\emerson \calculations\drainage_ memo.doc Hydrograph Return Period Recap Page 1 Hyd. Hydrograph Inflow Peak Outflow (cIs) Hydrograph No. type Hyd(s) description (origin) 1-Yr 2-Yr 3-Yr 5-Yr 10-Yr 25-Yr 50-Yr 100-Yr 1 SCS Runoff ------- ------- 4.96 -----..... ....._---.. 8.27 ------- ------- 12.53 Existing Parking To Existing Pond 2 SCS Runoff ------- ------- 1.78 ...---...-.. .........-..- 3.49 ------- ------- 5.84 Proposed to Existing Pond 3 SCS Runoff ------- ------- 11.88 ..---...... --.....--.. 19.80 ------- ..------ 30.03 Proposed to Pond 4 Reservoir 3 ------- 1.76 ------- ------- 2.41 -_....--- ------.. 12.68 Proposed Routed Proj. file: emerson.gpw Run date: 02-02-2006 Hydraflow Hydrographs by Intelisolve Hydrograph Summary Report Page 1 Hyd. Hydrograph Peak Time Time to Volume Inflow Maximum Maximum Hydrograph No. type flow Interval peak hyd(s) elevation storage description (origin) (cfs) (min) (min) (acft) (ft) (acft) 1 SCS Runoff 4.96 5 720 0.310 ......... ------ ............ Existing Parking To Existing Pond 2 SCS Runoff 1.78 5 720 0.112 ......- ------ -..--..... Proposed to Existing Pond 3 SCS Runoff 11.88 5 720 0.742 -..-... ------ ..-.......... Proposed to Pond 4 Reservoir 1.76 5 745 0.742 3 929.71 0.348 Proposed Routed Proj. file: emerson.gpw I Return Period: 2 yr Run date: 02-02-2006 Hydraflow Hydrographs by Intelisolve . . Hydrograph Summary Report Page 1 Hyd. Hydrograph Peak Time Time to Volume Inflow Maximum Maximum Hydrograph No. type flow interval peak hyd(s) elevation storage description (origin) (cfs) (min) (min) (acft) (ft) (acft) 1 SCS Runoff 8.27 5 720 0.526 _....... ------ ------ Existing Parking To Existing Pond 2 SCS Runoff 3.49 5 720 0.216 ..--- ------ ------ Proposed to Existing Pond 3 SCS Runoff 19.80 5 720 1.261 ....-- ------ ....-....... Proposed to Pond 4 Reservoir 2.41 5 750 1.261 3 930.76 0.611 Proposed Routed Proj. file: emerson.gpw Return Period: 10 yr Run date: 02-02-2006 Hydraflow Hydrographs by Intelisolve '. Hydrograph Summary Report Page 1 Hyd. Hydrograph Peak Time Time to Volume Inflow Maximum Maximum Hydrograph No. type flow interval peak hyd(s) elevation storage description (origin) (cfs) (min) (mln) (acft) (ft) (acft) 1 SCS Runoff 12.53 5 720 0.816 ---- ------ .....-...... Existing Parking To Existing Pond 2 SCS Runoff 5.84 5 720 0.364 ---- ------ ------ Proposed to Existing Pond 3 SCS Runoff 30.03 5 720 1.955 ....-- ------ ..----- Proposed to Pond 4 Reservoir 12.68 5 730 1.955 3 931.50 0.820 Proposed Routed Proj. file: emerson.gpw Return Period: 100 yr Run date: 02-02-2006 Hydraflow Hydrographs by Intelisolve . . Hydrograph Report Page 1 Hydraflow Hydrographs by Intelisolve Hyd. No. 1 Existing Parking To Existing Pond Hydrograph type = SCS Runoff Storm frequency = 100 yrs Drainage area = 2.20 ac Basin Slope = 0.0 % Tc method = USER Total precip. = 5.90 in Storm duration = 24 hrs Peak discharge = 12.53 cfs Time interval = 5 min Curve number = 90 Hydraulic length = 0 ft Time of cone. (Tc) = 10 min Distribution = Type II Shape factor = 484 Hydrograph Volume = 0.816 act! Hydrograph Discharge Table Time -- Outflow (hrs cfs) 11.92 10.11 12.00 12.53 << 12.08 10.18 ...End .. Hydrograph Report Page 1 Hydraflow Hydrographs by Intelisolve Hyd. No. 2 Proposed to Existing Pond Hydrograph type Storm frequency Drainage area Basin Slope Tc method Total precip. Storm duration = SCS Runoff = 1 00 yrs = 1 .23 ac = 0.0% = USER = 5.90 in = 24 hrs Peak discharge = 5.84 cfs Time interval = 5 min Curve number = 81 Hydraulic length = 0 ft Time of cone. (Tc) = 10 min Distribution = Type II Shape factor = 484 Hydrograph Volume = 0.364 acft Hydrograph Discharge Table Time -- Outflow (hrs cfs) 12.00 5.84 << 12.08 4.85 ...End .. Hydrograph Report Hyd. No. 3 Proposed to Pond Hydrograph type Storm frequency Drainage area Basin Slope Tc method Total precip. Storm duration Page 1 Hydraflow Hydrographs by Intelisolve = SCS Runoff = 100 yrs = 5.27 ac = 0.0% = USER = 5.90 in = 24 hrs Peak discharge = 30.03 cfs Time interval = 5 min Curve number = 90 Hydraulic length = 0 ft Time of cone. (Tc) = 10 min Distribution = Type II Shape factor = 484 Hydrograph Volume = 1.955 acft Hydrograph Discharge Table Time -- Outflow (hrs cfs) 11.92 24.21 12.00 30.03 << 12.08 24.39 ...End .. " Hydrograph Report Page 1 Hydraflow Hydrographs by Intelisolve Hyd. No. 4 Proposed Routed Hydrograph type Storm frequency Inflow hyd. No. Max. Elevation = Reservoir = 100 yrs = 3 = 931.50 ft Peak discharge Time interval Reservoir name Max. Storage = 12.68cfs = 5 min = New Pond = 0.820 acft Storage Indication method used. Outflow hydrograph volume = 1.955 acft Hydrograph Discharge Table Time Inflow Elevation ClvA ClvB ClvC ClvD WrA WrB WrC WrD Exfil Outflow (hrs) cfs ft cfs cfs cfs cfs cfs cfs cfs cfs cfs cfs 12.17 14.49 931 .50 12.68 1.22 11 .46 12.68 << 12.25 7.13 931.47 11.80 1.42 10.38 11.80 ...End '. Reservoir Report Page 1 Reservoir No. 1 - New Pond Pond Data Pond storage is based on known contour areas. Average end area method used. Hydraflow Hydrographs by Intelisolve Stage I Storage Table Stage (ft) Elevation (ft) Contour area (sqft) Iner. Storage (aeft) Total storage (aeft) 0.00 1.00 2.00 3.00 4.00 5.00 928.00 929.00 930.00 931.00 932.00 933.00 7,625 8,990 1 0,450 12,045 13,720 14,600 0.000 0.191 0.223 0.258 0.296 0.325 0.000 0.191 0.414 0.672 0.968 1.293 Culvert I Orifice Structures Weir Structures [A] [B) [C) [D) [A] [B) [C) [D) Rise In = 18.0 8.0 0.0 0.0 Crest Len ft = 12.48 0.00 0.00 0.00 Span In = 18.0 8.0 0.0 0.0 Crest EI. ft = 931.00 0.00 0.00 0.00 No. Barrels = 1 1 0 0 Weir Coeff. = 2.60 0.00 0.00 0.00 Invert EI. ft = 928.00 928.00 0.00 0.00 Weir Type = Riser Length ft = 25.0 0.0 0.0 0.0 Multi-Stage = Yes No No No Slope % = 1.00 0.00 0.00 0.00 N-Value = .013 .013 .000 .000 Orif. Coeff. = 0.60 0.60 0.00 0.00 Multi-Stage = nfa Yes No No Exfiltration Rate = 0.00 infhrfsqft Tailwater Elev. = 0.00 It Note: All outflows have been analyzed under inlet and outlet control. Stage I Storage I Discharge Table Stage Storage Elevation ClvA Clv B ClvC Clv D WrA WrB WrC WrD Exfil Total ft aeft ft efs efs efs efs efs efs efs efs efs efs 0.00 0.000 928.00 0.00 0.00 0.00 0.00 1.00 0.191 929.00 1.29 1.20 0.00 1.20 2.00 0.414 930.00 2.04 1.97 0.00 1.97 3.00 0.672 931.00 2.54 2.54 0.00 2.54 4.00 0.968 932.00 15.13 0.49 14.64 15.13 5.00 1.293 933.00 17.50 0.22 17.27 17.50 . ~ Pond StageNolume Data Emerson Process Management - Rosemount Inc. Chanhassen, Minnesota 1/31/2006 Storm Water Pond - Volume (Outlet @ 928.0) DEAD STORAGE Cumulative Cumulative Elev Area(acre) Area(sq.ft.) Volume(c.f.) Volume(c.f.) Vol. (Ac-Ft.) 922.0 0.0 1,280 0 0 0.00 923.0 0.0 1,840 1,560 1,560 0.04 924.0 0.1 2,400 2,120 3,680 0.08 925.0 0.1 3,100 2,750 6,430 0.15 926.0 0.1 3,800 3,450 9,880 0.23 927.0 0.1 4,600 4,200 14,080 0.32 928.0 0.2 7,625 6,113 20,193 0.46 Required NURP Pond Volume (111 Runoff) DrainaQe Area Runoff (in) Volume (ac-ft) 5.27 1.00 0.44 Storm Water Pond - Volume (Outlet @ 928.0) LIVE STORAGE Cumulative Cumulative Elev Area(acre) Area(sq.ft.) Volume(c.f.) Volume(c.f.) Vol. (Ac-Ft.) 928.0 0.2 7,625 0 0 0.00 929.0 0.2 8,700 8,163 8,163 0.19 930.0 0.2 9,860 9,280 17,443 0.40 931.0 0.3 11,000 10,430 27,873 0.64 932.0 0.3 12,300 11 ,650 39,523 0.91 POND 1 Outlet = 18" Pipe @ 928.0 SCS 24 Hour Type II Design Storm Discharge Routing Frequency Rainfall (in) qn (cfs) Qout (cfs) Peak Elev. Storage (cf) 2 2.8 11.88 1.76 929.71 15,159 10 4.15 19.80 2.41 930.76 26,615 100 5.9 30.03 12.68 931.50 35,719 . . 1 J POND SKIMMER GRATE 48-57 HAALA INDUSRTIES, SLEEPY EYE, MN (1 -507 -794-5821), OR APPROVED EQUAL HOT-DIPPED GALVANIZED HINGED GRATE #4 BARS @ 12" OC TOP AND BOTTOM ELEV=931.77 $- ELEV=931.02 iNWL=928.0 INV=928.0 18 STORM INV=919.14 .. :~ 48" 5" 0-J 01 o 0 :=:J ...L- _ -'- PRECAST CONCRETE BASE INV= 0) POND OUTLET STRUCTURE :z ~_~-' . '-.. lh'" ~:. _. .... '\~~~;=c..2j,.:~_~_<'~'.:~~';9fit ~' "" ..:..............::::.::..~...~~.....: ....... ~ . ;___,,_~____:_~_:u:n'::h~:'~_::,::~u;,:~,:__m:_~'i'" ".l....::: ~'..:,<:~,.::~~,.. ::.':: __' '.,~. i. _'-' "---- - - ~.._--..nmrmn:.'._'<:.:~.:~~.-:-__nu- ,----..----'~:., "', '.' , , . . ',' " "" l..~"" >- -'. . . ". .:' . " ..' / / ,....\ ....\ ~ \"'\ '\' '" . r'~~, \ \ ..~\." \. \'\L, J . // i. ,~'." .,' .r...~lt>i,.i~ '11'. './ .' .....- j -:: :'r,. "1'. ,---/l"', 1 ; ~ ~ ~'.\~. \.' ....... .. 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