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HomeMy WebLinkAboutDrainage Reports - 06/10/2014S6 L NORTHERN ENGINEERING May 21, 2014 City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, Colorado 80521 ADDRESS: PHONE:970.221.4158 WEBSITE;. 200 S. College Ave. Suite 10 www,northernengineering:com Fort Collins, CO 80524 FAX: 970:221.4159 RE: Drainage Addendum Letter for Bucking Horse Filing 2 Dear Staff: City of Ft. Collins pro ed Plans Approved By Date - 6-10-/ Northern Engineering is pleased to submit this Drainage Addendum Letter for the proposed Bucking Horse Filing 2 project for your review. The focus of this drainage summary letter is the final SWMM model reviewed and approved with the Bucking Horse Filing 2 project ("Final Drainage Report for Bucking Horse Filing 2", December 17, 2012, by Northern Engineering), and our revisions to the model in order to reflect site plan changes and percentage imperviousness revisions as described in our previous Drainage Summary Letter, dated May 7, 2014. In an effort to streamline modeling of the condition now proposed for the site, we have re -modeled the overall site using the computer program EPA SWMM Version 5.0. The modeling that we completed utilized the SWMM modeling approved with Bucking Horse Filing 2 as summarized in the report, "Final Drainage Report for Bucking Horse Filing 2", December 17, 2012, by Northern Engineering. This model was converted to EPA SWMM, and then modified to reflect site plan changes (Basin 105 percentage imperviousness) and changes to detention pond 215 (re -shaping to allow for creation of a horse pasture). Two changes have been made to the current SWMM model. First, percentage imperviousness for SWMM Basin 105 was decreased in the current model. The SWMM approved with the Final Drainage Report in December 2012 showed this basin with a percent impervious value of 75%. With the proposed site plan for Bucking Horse Filing 3, the averaged percent impervious value will be reduced by 6% to a value of 69%. This decrease in percentage imperviousness is now reflected in the current model. Second, the stage -storage for Pond 215 has been changed in the current SWMM model. The pond has been re -graded in order to allow for a horse pasture to be created. The current SWMM model shows a required 100-year volume in Pond 215 of 24.54 acre-feet (previously 28.80 acre-feet) resulting in a 100-year water surface elevation of 4883.97. Please see revised SWMM modeling output provided in Attachment 1, and revised Pond 215 information provided in Attachment 2. 4 r s Additionally, the design of the storm culvert under Nancy Gray Avenue (Storm Drain 9) has been revised based on the modifications to the SWMM model described above. The original SWMM modeling showed a peak 100-year discharge of 338.9 cfs, whereas, the current modeling shows 206.8 cfs. Based on this new 100-year discharge, the culvert has been re- analyzed. Please see Attachment 3 for revised culvert analyisis. If you should have any questions as you review this, please feel free to contact us at your earliest convenience. Sincerely, NORTHERN ENGINEERING SERVICES, INC. Aaron Cvar, PE Project Engineer ATTACHMENT 1 h 3 y c ., O I'm # N # + ro a # + Ol x + w w + + H y + + O + # Jl JJ Y O O # Ul N + O O x t C c rz + o 0 x w E+ o 0 + ro E H x N N O O O Q I + .-I O OY > 1 1 000 N # N U lI1+ O QN N N �000 Fa 1 I H000 a z > > .. + NL+ L. W OO W O QO HOO -00 # N > Uk U i1 z z>. zz xb�z zOOOOM + U N ro+ + 0 7 + + N O m t . •o 'o rn . + H N a+ x N# W W J4 -1 JN + row vi x x C+ •• O a ?� N Ul 01 w N k + O x N C 010 a� $ >. 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I£ w w I o H o 0 0 0 0 I I I I I I I I I E— U I m�OH�NPO a U 1 Ol N r H l0 M O E O 0 I I I m m r m o H o xN 1 I I ro> w l n I I I I I I I% U I C I Ol N 10 H O O O m M O P P I N U• i I P P 1I1 P P P P P H t 0 10 H I U I •• I O. y 0 0 0 0 0 0 H O O H 1 W H N o 0 0 0 0 0 0 0 0 o O O 1 o u .c 1 I a I I E -i o N E+ •O I I I I E—m I OWN N vl Il1p H O� 0000 I E O U I I -. i H I O m m r m O o 0 0rn N 1O M N I X w I I N— 1 H HMMIp H H I £ 1 I I I I I I F H H H F F F H H H H H H H I I OOOpOOSN >+>+NN £ £ I O.I Z Z Z Z Z Z Z E E£££E£ I �.l0000000np000 I F I U U U U U U U O O O p p I * + I I # # I I I * + I 1 * K I I + a+ I 1 I # # I I # to K I I * k I I I K YI K I 1 + * I I k O+# I I I * ro+ I I t UI t I I * C+ I 1 I K K I I 1 # m# I 1 k O K I C I + OI 0 1* I 1 k K I 1 + + I I K # I I I + O* I 1 H # N# I ro l + ro* 1 ro 1 44 1 W « K I UJ I O # H K I 1 + W* I W I W I 'O 1 0 # O+ 1 0 I H N ul + 1� t 1 a, I El W # C# I O I .0 + W+ 1 #� 1 O O m H k a* I a 1 O 1 ?1 Z I E + mt I m 100PHN K O# I O 1 0 1 fn + r7+ I I I I I I I O N H N 1 H o o H ?C I N O O P N �l I N N N N N N H O O O Ifl O N 0) f6 a r I �ro I I O m E l o I m a 1 1 U I I I I 3 1 I .-I O I Z .i I I a W I I N W I M a w I O D E I o I x ppo H I Q Z I I I I I I I I E l r I I m I r I I W 1 I l i n o I I V I h I I 1 c I I a m i rn I W N I I H I O I N al I I H N I a a 1 I o x I 1 x I 1 I I I Vl I r I I ro l r I I C I I I W I O I I 1 ✓ 1 1 O I I I tl1 I I I I I I 1 ATTACHMENT 2 \ \ I LOW FLOW I \\ \ \\\ \I `,QHANNEL I \\ \\ \\\ OT C \\ Co 2.8� ij bb.- 50 DRAINAGE \ EASEMENT 80'.76, IN VOLUME BELOW PASTURE: 8.89 AC -FT (388,457 cu. ft.) LOWEST PASTURE ELEVATION: 4881.90 QUALITY PLD ,� r I17' ~�I—JI1S toy i I OUTLOT D 1 I \\gym\\\\\ �• 111I � �\ \ 111\\ ti \\ • I\II �� 111111 II ` Awl, 1 \IIIII Ak \1 GW FLOW-LHANNEL —4882- I�l \\ \ -----------//// \\_--------------------------- -2jl_ I 27 SS 2]' SS 27" SS — �� 30" SS 30" SS — \\-�\ \\—T_`z itw--__`ig=w—y—izw r 12"w �y BUCKING HORSE Revised Pond 215 Stage Storage 5/21/2014 Incremental Incremental Volume Volume Elevation Area (CF) (acre feel) Cummulative Cummulative Volume Volume (CF) (acre feel) 4878.50 83.51 1.31 0.00 1.31 0.00 4878.70 1939.38 166.73 0.00 168.04 0.00 4878.90 5550.06 893.28 0.02 1061.32 0.02 4879.10 9377.45 2390.64 0.05 3451.96 0.08 4879.30 13120.60 4638.70 0.11 8090.66 0.19 4879.50 16692.02 7634.40 0.18 15725.06 0.36 4879.70 18074.08 11158.04 0.26 26883.10 0.62 4879.90 18559.28 14803.98 0.34 41687.08 0.96 4880.10 19729.65 18636.07 0.43 60323.15 1.38 4880.30 20709.68 22698.85 0.52 83022.00 1.91 4880.50 19936.04 26776.16 0.61 109798.16 2.52 4880.70 19616.75 30692.79 0.70 140490.95 3.23 4880.90 21430.37 34895.52 0.80 175386.47 4.03 4881.10 12481.38 38304.77 0.88 213691.24 4.91 4881.30 10381.47 40513.26 0.93 254204.50 5.84 4881.50 10148.69 42537.22 0.98 296741.72 6.81 4881.70 11244.42 44675.00 1.03 341416.72 7.84 4881.90 12502.64 47040.20 1.08 388456.92 8.92 4882.10 15094.65 49772.42 1.14 438229.34 10.06 4882.30 16757.22 53001.91 1.22 491231.25 11.28 4882.50 17580.68 56417.54 1.30 547648.79 12.57 4882.70 18545.75 60077.85 1.38 607726.64 13.95 4882.90 16561.88 63601.00 1.46 671327.64 15.41 4883.10 15839.95 66807.99 1.53 738135.63 16.95 4883.30 15939.25 69987.69 1.61 808123.32 18.55 4883.50 16200.29 73194.68 1.68 881318.00 20.23 4883.70 16476.23 76462.76 1.76 957780.76 21.99 4883.90 16609.07 79776.89 1.83 1037557.65 23.82 4884.10 16360.49 83078.76 1.91 1120636.41 25.73 4884.30 1 15653.20 86301.26 1.98 1206937.67 27.71 4884.50 5626.98 88401.89 2.03 1295339.56 29.74 4884.70 5630.04 89527.57 2.06 1384867.13 31.79 4884.90 5631.67 90653.88 2.08 1475521.01 33.87 4885.10 5799.24 91781.94 2.11 1567302.95 35.98 4885.30 6494.28 93054.83 2.14 1660357.78 38.12 4885.50 5902.19 94264.37 2.16 1754622.15 40.28 4885.70 6006.39 95454.47 2.19 1850076.62 42.47 4885.90 6191.96 96673.47 2.22 1946750.09 44.69 4886.10 11577.65 98358.72 2.26 2045108.81 46.95 4886.30 6662.01 1 100254.09 2.30 2145362.90 49.25 ATTACHMENT 3 ` " HY-8 Culvert Analysis Report rn - Table 1 - Summary of Culvert Flows at Crossing: Storm Drain 9 Headwater Elevation (ft) Total Discharge (cfs) Culvert 1 Discharge (cfs) Roadway Discharge (cfs) Iterations 4887.54 100.00 100.00 0.00 1 4887.69 110.68 110.68 0.00 1 4887.82 121.36 121.36 0.00 1 4887.95 132.04 132.04 0.00 1 4888.08 142.72 142.72 0.00 1 4888.21 153.40 153.40 0.00 1 4888.33 164.08 164.08 0.00 1 4888.45 174.76 174.76 0.00 1 4888.79 185.44 185.44 0.00 1 4888.90 196.12 196.12 0.00 1 4889.01 206.80 206.80 1 0.00 1 1 4892.23 413.81 413.81 1 0.00 1 Overtopping W( Q w Rating Curve Plot for Crossing: Storm Drain 9 4889.0 Y 4888.6 0 Y T 4888.4 m w m 4888.2 m 4888.0 a� 4887.8 4887.6 Total Rating Curve Crossing,. Storm Drain 9 Total Discharge (cis) Table 2 - Culvert Summary Table: Culvert 1 Total Culvert Headwat Inlet Outlet Outlet Taihvater Discharg Discharg er Control Control Flow Normal Critical Outlet Taihvater Velocity Velocity e Ids) a (ds) Elevftation Depth (ft) Depth (ft) Type Depth (ft) Depth (ft) Depth (fi) Depth (ft) MIS) MIS) 100.00 100.00 4887.54 2.213 0.746 1S2n 1.471 1.530 1.479 1.356 6.464 2.901 110.68 110.68 4887.69 2.356 0.825 1-S2n 1.556 1.614 1.563 1.435 6.652 2.996 121.36 121.36 4887.82 2.493 0.901 1-S2n 1.641 1.698 1.647 1.511 6.816 3.084 132.04 132.04 4887.95 2.625 0.973 1-S2n 1.726 1.776 1.726 1.583 6.981 3.167 142.72 142.72 4888.08 2.753 1.043 1-S2n 1.808 1.846 1.815 1.653 7.082 3.245 153.40 153.40 4888.21 2.878 1.110 1-S2n 1.888 1.917 1.896 1.720 7.213 3.318 164.08 164.08 4888.33 3.002 1.175 1-S2n 1.969 1.987 1.977 1.785 7.327 3.388 174.76 174.76 4888.45 3.125 1.237 1-S2n 2.049 2.057 2.056 1.847 7.439 3.454 185.44 185.44 4888.79 3.248 3.460 2-M2 2.131 2.123 2.124 1.908 7.587 3.516 196.12 196.12 4888.90 3.372 3.575 2-M2 2.215 2.182 2.187 1.967 7.753 3.577 206.80 206.80 4889.01 3.497 3.675 2-M2 2.299 2.241 2.248 2.025 7.917 3.635 c Inlet Elevation (invert): 4885.33 ft, Outlet Elevation (invert): 4884.72 ft Culvert Length: 135.97 ft, Culvert Slope: 0.0045 0.- `0 Culvert Performance Curve Plot: Culvert 1 w %000 c 4888 a� W 4887 m w m 9 4887 �o a� Performance Curve Culvert: Culvert i Elev 00 120 140 160 180 200 Total Discharge (cfs) «. .> Water Surface Profile Plot for Culvert: Culvert 1 K.w C O Y W S Crossing = Storm Drain 9, Design Discharge - 206:8 cfs. Culvert - Culvert 1, Culvert Discharge - 206.8 cfs irnet Station: u.uu tt Inlet Elevation: 4885.33 ft Outlet Station: 135.97 ft Outlet Elevation: 4884.72 ft Number of Barrels: 4 Station (ft) Culvert Data Summary - Culvert 1 Barrel Shape: Circular Barrel Diameter: 3.50 ft Barrel Material: Concrete Embedment: 0.00 in Barrel Manning's n: 0.0130 Inlet Type: Conventional Inlet Edge Condition: Square Edge with Headwall Inlet Depression: NONE Table 3 - Downstream Channel Rating Curve (Crossing: Storm Drain 9) Flow (cfs) Water Surface Elev (ft) Depth (ft) Velocity (ft/s) Shear (psf) Froude Number 100.00 4886.08 1.36 2.90 0.25 0.48 110.68 4886.16 1.44 3.00 0.27 0.49 121.36 4886.23 1.51 3.08 0.28 0.49 132.04 4886.30 1.58 3.17 0.30 0.49 142.72 4886.37 1.65 3.24 0.31 0.50 153.40 4886.44 1.72 3.32 0.32 0.50 164.08 4886.50 1.78 3.39 0.33 0.50 174.76 4886.57 1.85 3.45 0.35 0.50 185.44 4886.63 1.91 3.52 0.36 0.51 196.12 4886.69 1.97 3.58 0.37 0.51 206.80 4886.74 2.02 3.63 0.38 0.51 Tailwater Channel Data - Storm Drain 9 Tailwater Channel Option: Trapezoidal Channel Bottom Width: 20.00 ft Side Slope (H:V): 4.00 (_:1) Channel Slope: 0.0030 Channel Manning's n: 0.0300 Channel Invert Elevation: 4884.72 ft Roadway Data for Crossing: Storm Drain 9 Roadway Profile Shape: Constant Roadway Elevation Crest Length: 100.00 ft Crest Elevation: 4892.23 ft Roadway Surface: Paved Roadway Top Width: 76.00 ft