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Home My WebLink AboutEAST RIDGE C-STORE - PDP - 33-98G - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORT (3)100-year Runoff for Developed Conditions Rational Method Procedure Basin(s) DIRECT RUNOFF Comments Design Point Area acre(s) t, min C' A acre(s) am a Intensity in/hr Flow (Q) cfS 100 10T— 101 9.86 0.66 200 • 47— 300 300 00 0.01 S•de Site 0.91 0.82 5.19 0.75 9.86 7.40 Project Number: 2468 Designer: Herman H. Feissner, P.E. Project Name: East Ridge C-Store Date: 311512007 100-year to Calculations for Developed Conditions Raf onaf Method PrDWxa DATA OVERLAND TIME OF FLOW(tj CHANNELIZED TIME OF FLOW(tn) CHANNELIZED TIME OF FLOM FINAL 1 1. Design Pain -; Area acre(s) Runoff Coeff G'b Length �� ft Slope % 4 M .. Length r'. it Slope % elocity 1, ltc In min th -' Slope % Ve ..:min Computed Comments 100 0.21 0.99 42 2.00 1.06 71 0.60 1.55 0.77 27 2.00 2.83 0.16 5.00 101 0.14 OA7 fi3 5.75 5.19 0 0.00 0.00 0.00 0 0.00 OAO 0.00 &19 Isfte 200 0.84 29 25.00 O.BB 97 0.90 1.90 0.00 111 2.8D 3W 0.00 8.00 300 S0.91 0.19 Amen MMIUM T. Slb 0.82 1 8.19 Pmfed N.mber2408 De gner Haman H Feiss . P.E. Pml.d Nan.E.& R , CSfae Dale: 3/15TW7 10-year Runoff for Developed Conditions Rational Method Procedure Basin(s) DIRECT RUNOFF Comments Design Point Area acres C10 tc, min C*A acre s Rainfall Intensity in/hr Flow (Q) ,afs 100 100 0.21—i 0.79 5.00 0.17 4.87 0.81 6.14 0.05 4.62 0.25 101 101 0.14 0.38 200 200 0.56 0.68 5.00 0.38 4.87 1.85 300 300 0.03 0.15 5.00 0.01 4.87 0.03 Site Site 0.91 0.66 6.14 0.60 4.62 177 Project Number: 2468 Designer: Herman H. Feissner, P.E. Project Name: East Ridge C-Store Date: 31152007 10-year t , Calculations for Developed Conditions Raf amal Method Pocedure DATA OVERLAND TIME OF FLOWJQ CHANNELIZED TWE OF FLOW(tu) CHANNELIZED TIME OF FLOW)tu) FINAL b Design Point .:..,,Area Runoff Coefftien.. :�I Lit,,.;.,. Slope 6 m ,,Length Sk" °/e Velocity fUsec 4+ min Length it " . Slope -• % Velocity fU _Y:-to Computed 1. min CovameMs�s. "�� i 100 100 021 0.79 42 2.00 1 2.97 71 0.60 1.55 0.77 27 2.00 2.83 0.16 5.00 _ 101 101 0.14 0.311 83 5.75 5.98 0 0.00 0.00 0.00 0 0.00 0.D0 0.00 - - 200 200 0.56 0.68 29 25.00 1.46 97 0.90 1.90 0.85 1 111 280 3.35 0.55 A00 300 300 0.03 0.15 JAamtrue 1khrnun T. 5,00 it Site Sb 0.91 0.66 1 1 1 1 1 1 1 IR14 Pmjed Number. 2406 Dealener. Herman H Felxmw, P.E. Project Name: Eaai Ridge C-SYwe Date: 1H52007 Runoff Coefficient Calculations Rational Method Procedure Basin(s) Area ftz Area ac Type of Development Composite Cto Composite C100 100 9174.81 0.21 Business_ 0.79 6135.70 0.14 Business 0.38 0.99 101 0.47 200 24490.23 0.56 Business 0.68 0.84 300 1503.78 0.03 Landscape 0.15 0.19 Site 39801 0.91 Business 0.66 0.82 Project Number: 2468 Designer: Herman H. Feissner, P.E. Project Name: East Ridge C-Store Date: 311512007 Rainfall In Excerpt from Time Minutes St6em Event 10-year 100-year 5 4.87 9.95 10 3.78 7.72 15 3.19 6.52 20 2.74 5.60 25 2.44 4.98 30 2.21 4.52 35 2.00 4.08 40 1.83 3.74 45 1.69 3.46 50 1.58 3.23 55 1.48 3.03 60L 1.40 2.86 Table Project Number: 2468 Designer: Herman H. Feissner, P.E. Project Name: East Ridge C-Store Date: 311512007 The C-Store project site is divided into four developed basins (Refer to Sheet 5 of 5, Preliminary Drainage and Erosion Control Plan). Basins 100, 101, and 200 have similar internal developed drainage patterns. The overland flow from landscaped areas and the sheet flow from parking and sidewalk areas spills to curb and gutter that, in turn, spills on to Vicot Way (Basins 100 & 101) and Sykes Drive (Basins 101 & 200). At this time, we do not plan to construct any below grade infrastructure (e.g., storm drain pipe, inlets, and etc.). Basin 300 is a short and wide basin along the north property line of the project site that will be landscaped and drain to the north. The attached 10-year (minor storm) and 100-year (major storm) developed runoff calculations are based on the Rational Method procedure. This calculation method is recommended by the City of Fort Collins for sites less than 5 acres. During the minor and major storm events, the estimated develop runoff is Q10=2.77 cfs and Qi00=7.40 cfs, respectively. If the Qioo estimate is converted into a unit release rate, which is done by dividing the area of the project site into the developed runoff value for the site, we found that our unit release rate is less than what TST estimated with SWMM (8.09 cfs/ac versus 9.94 cfs/ac). Despite this difference, the rational method estimate is reasonable and valid for the proposed land use. Please feel free to contact me at (970) 484-1921 at your convenience if you have any questions regarding this report. We thank you for your time and consideration in reviewing this drainage report submittal. Sincerely, JIM SELL DESIGN, INC. Herman Feissner, P.E. Enclosure cc: File March 16, 2007 City of Fort Collins Stormwater Utility 700 Wood Street PO Box 580 Fort Collins, CO 80522 RE: East Ridge C-Store PDP Submittal Dear Basil: LANDSCAPE ARCHITECTURE PLANNING ENGINEERING GRAPHIC DESIGN The following letter report has been prepared for the East Ridge C-Store in accordance with the storm drainage design guidelines set forth in the City of Fort Collins Stormwater Drainage Design Criteria and Construction Standards (Dated: January 1997). The C-Store project site is an undeveloped lot within the East Ridge Subdivision. It is bounded to the north by undeveloped land; to the east by Vicot Way (proposed); to the south by Sykes Drive (proposed); and to the west by Timberline road. We assume herein that construction progress within the East Ridge Subdivision will be far enough along that the necessary storm drainage conveyance, storage, and water quality infrastructure will be in place and serviceable prior to the development of the C-Store project site. TST, Inc. (TST) recently submitted the Final Drainage Report for East Ridge Subdivision to the City of Fort Collins for review and approval. According to this report, the project site straddles basins 50 and 54. With respect to the contours shown on TST's Final Drainage Plan, it looks like the C-Store project site should fall within the limits of basin 50. Basin 54 should traverse along the north property line of the subject site. Basin 50 is comprised of f2.82 acres of mostly undeveloped land, except for the existing Timberline Road improvements, set aside for commercial development and an improved Timberline Road section and alignment. Basin 54 is comprised of f4.70 acres of undeveloped land, except for the improved Timberline Road improvements, set aside for multi -family development and an improved Timberline Road section and alignment. The commercial land use proposed by TST is consistent with the current proposed land use. The soils within the project site are NRCS Hydrologic Soil Group `B'. The proposed C-Store grading is consistent with TST's proposed overlot grading plan. There are no off -site areas that drain on to the project site. In general, the developed site runoff will sheet flow to Vicot Way and Sykes Drive and combine with developed runoff from other developed areas in basin 50. In Sykes Drive at TST's design point 50, the developed runoff spills into a proposed Type `R' Inlet (Sump). This inlet discharges into storm drain infrastructure proposed by TST that outfalls into Detention Pond 1. No on -site detention or water quality is required because it is provided in Detention Pond 1. 153 WEST MOUNTAIN AVENUE FORTCOLLINS, COLORADO 80524 P970.484.1921 F970.484.2443 INFO@JIMSELLDESIGN.COM 11MSELLDESIGN.COM