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Home My WebLink AboutDrainage Reports - 10/29/2004TST Jill 748 Whalers Way, Bldg, D Fort Collins, CO 80525 970.226.0557 metro 303.595.9103 fax 970.226.0204 TST, INC. CONSULTING ENGINEERS June 25, 2004 PROPERTY OF FO RT T c� 10- V T. m ItyOf Ft. Collin Mr. Basil Hamden APp wed Plans City of Fort Collins Storm Water Division Approved By P.O. Box 580 Date fy / 21 /04 Fort Collins, CO 80522 '- Re: Maple Hill First Replat Project No. 1003.0000.00 Dear Mr. Hamden: We are pleased to submit to you the First Replat for the Maple Hill Subdivision. The purpose of this letter is to describe the changes we are making to the approved Maple Hill plans. Three lots were added to the site. The resulting change in the C values and thus the runoff in the 2-yr and 100-yr storms is negligible. The additions of these three lots should have no impact on the current design. Per your request, we have included with this letter calculations showing the depth of water in the side lot swales in Blocks 1 and 2 of the Maple Hill First Replat. (These Blocks were formerly 17 and 22) Based on the current design, a six foot wide drainage easement along the lot lines is sufficient to pass the flows from the open spaces to the west of the units in the 100-yr storms. We do not believe that it is necessary to install an inlet and storm sewer pipe to drain the open space tracts west of these lots. Please see the attached calculations for further information. We look forward to your review and approval and will gladly answer any questions you may have. Sincerely, TST, INC. 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G 11 1 Holm SG..■■..� 118 ENim. 500E m GG:G:G:G ewa G'�GG:GSGEG�:::S:'�.G - •••n■■■■..■■■..■ ... ' ■■■■■■■ �. �....n::..GG. ■■ ■ . m■..■■.. i�GG:GGG:SG I:::G:GG::G I!■■■..■■ IGGGG:S:::GG�GGGGGGGGG:GIGGIGGGGG:G�LCG�G:G . ....................0 ::G:S:::::::G:G::GGGGG::S® ................ ... 11 "■ �i®i i��II Ii�� ®Iiiii�®�ii .............................■■■■■■■■■■.!■■■■ G:::G::G:G:::GG::GGG:000GG:::GmmiimS®SmSS I..■. ::� ::EG9s::E::E�:sEEEB9�E898G � 9EBG::::::... ��mi��EG��6miE:GGE��0 .......■ .......................■...... ■ ■ 11111/111 11111 :GIMill .■■■ GG�:G■■■■�s Analysis of Trapezoidal Grass -Lined Channel Project: Maple Hill Replat Channel ID: Swales Between Lots F<-----------T -----------= Y0 Y 1 a, 4Z 2Z2 Z1 a----B------7 Desian Information Grass Type: A B C D E Limiting Manning's N 0.060 0.040 0.033 0.030 0.024 Soil Type: Max. Velocity (Vm,,) Max. Froude No. (Fm.J Non -Sandy 7.0 fps 0.80 Sandy 5.0 fps 0.60 Design Information Enter Grass Manning's N N = 0.035 Type of Grass (A,B,C,D, or E) Other Grass Channel Invert Slope So = 0.0200 ft/ft Bottom Width B = 0.00 It Left Side Slope Right Side Slope Zt = Z2 = 50.00 ft/ft nn 50.00 ft/ft Z S�ot� 5(oQeS Design Discharge Q = 3.0 cfs Check one of the following soil types Sandy Soil check, OR Non -Sandy Soil X check Flow Condition Calculated Water Depth Y = 0.22 ft 4 - D� Top Width T=, 22.00,ft e- SPA Flow Area A = 2.42'sq ft Wetted Perimeter P = 22.00 ft Hydraulic Radius R = 0.11 ft Flow Velocity. V =, 1.38;fps Hydraulic Depth D =, 0.1 1!ft Froude Number Fr=� 0.73' Discharge (Check) Q=� 331cfs UD-Channels 0.00, Flow Analysis 6/24/2004, 3:41 PM Analysis of Trapezoidal Grass -Lined Channel Project: Maple Hill Replat Channel ID: Swales Between Lots Warning 04 F ^ c-----------T -- --Ya----- K Y 1� ® 1 Zl ------7 Z2 Design Information Grass Type: A B C D E Limiting Manning's N 0.060 0.040 0.033 0.030 0.024 Soil Type: Max. Velocity (V,„ax) Max. Froude No. (Finax) Non -Sandy 7.0 fps 0.80 Sandy 5.0 fps 0.60 Design Information Enter Grass Manning's N N = 0.035 Type of Grass (A,B,C,D, or E) Other Grass Channel Invert Slope So = 0.0200 ft/ft Bottom Width B = 0.00 It Left Side Slope Right Side Slope Z1 = Z2 = 4.00 ft/ft Z5 5: p S�o 4.00 ft/ft a� P e—S Design Discharge Q = 3.0 cfs Check one of the following soil types Sandy Soil check, OR Non -Sandy Soil X check Flow Condition Calculated Water Depth Y Top Width T = 4.40 ft L— Flow Area A =, 1.21, sq It Wetted Perimeter P = 4.54,ft Hydraulic Radius R =' 0.27'ft Flow Velocity. V = 2.50 fps Hydraulic Depth D = 0.28 It Froude Number Fr = 0.84 Discharge (Check) 0=1 3.O1cfs Warning 04: Froude No. exceeds USDCM Criteria Manual Volume II recommendation. UD-Channels v1.00, Flow Analysis 6/24/2004, 3:41 PM FE Analysis of Trapezoidal Grass -Lined Channel Project: Maple Hill Replat Channel ID: Swales Between Lots Warning 04 FA NN,<T 0010 Yo Y 1� • Z1 E----- B------ > Z2 Design Information Grass Type: A B C D E Limiting Mannin 's N 0.060 0.040 0.033 0.030 0.024 Soil Type: Max. Velocity (Vm,,) Max. Froude No. (Fina,) Non -Sandy 7.0 fps 0.80 Sandy 5.0 fps 0.60 Design Information Enter Grass Manning's N N = 0.035 Type of Grass (A,B,C,D, or E) Other Grass' Channel Invert Slope So = 0.0200 ft/ft Bottom Width B = 0.00 ft Left Side Slope Z1 = 4.00 ft/ft t 7 zs � 5'bte S�aS Right Side Slope Z2 = 4.00 Wit Design Discharge Q = 4.0 cis Check one of the following soil types Sandy Soil check, OR Non -Sandy Soil X check Flow Condition Calculated Depth Watereg, Y = " 0:62 ft � p Top Width T = 4.96.E s Flow Area A = 1.54 sq ft Wetted Perimeter P = 5.11 ft Hydraulic Radius R = 0.30 ft city V =' 2.7Q fps Depth D = 0.31 ftumber L Fr =1 0.86 e (Check) Q=) 4 sr„ s"4`21cfs Warning 04: Froude No. exceeds USDCM Criteria Manual Volume 11 recommendation. LID -Channels v1.00, Flow Analysis 6/24/2004, 5:02 PM Project: Channel ID: Analysis of Trapezoidal Grass -Lined Channel F ^ T Yo Y 1� • w Zl E_____B______> Design Information Grass T e: A B C D E Limiting Mannin 's N 0.060 0.040 0.033 0.030 0.024 Soil Type: Max. Velocity (Vm,,) Max. Froude No. (Fm„) Non -Sandy 7.0fps 0.60 Sandy 5.0 fps 0.60 Design Information Enter Grass Manning's N N = 0.035 Type of Grass (A,B,C,D, or E) Other Grass Channel Invert Slope So = 0.0200 ft/ft Bottom Width B = 0.00 it Left Side Slope Z1 = 50.00 ft/ft �` 5�2 Right Side Slope Z2 = 50.00 ft/ft Design Discharge Q = 4.0 cfs Check one of the following soil types Sandy Soil check, OR Non -Sandy Soil X check Flow Condition Calculated Water Depth Y = 0.24 tt Top Width T = 24.00 ft Sp rcy,a Flow Area A = 2.88 sq ft Wetted Perimeter 'P = 24.00 ft Hydraulic Radius R = 0.12 It Flow Velocity V = 1.46 fps Hydraulic Depth D = 0.12 ft Froude Number Fr= 0.75 Discharge (Check) Q= ARM."*, ! cfs LID -Channels v1.00, Flow Analysis 6/24/2004, 5:02 PM No Text No Text