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HomeMy WebLinkAboutDrainage Reports - 09/09/2003ri NENORTHERN I ENGINEERING L SERVICES, INC. Tina! neck Report' August 28, 2003 Mr. Wes Lamarque City of Ft. Collins Stormwater Utility Development Review Division 235 Matthews Fort Collins, Colorado 80522-0580 RE: Lot 8 at Harmony Safeway Marketplace Dear Wes: 3�IEOWE SM 4 2003 I As a part of the approved plan set for the Harmony Safeway Marketplace, Lot 8 is located in the northwest corner of the property. This letter is intended to provide an overview of the proposed development's impact on the existing drainage design approved for the Harmony Safeway Marketplace, dated March 7, 1997 by Northern Engineering Services, Inc. From the approved "Final Drainage Report for Harmony Safeway Marketplace P.U.D.," the sub -basins designated with an N prefix were designed such that developed runoff would be directed towards the northeast corner of the site to a proposed detention pond, and then ultimately to the Golden Meadows Regional Detention Pond. Basins designated with an S prefix were designed to release into an open channel, through proposed culverts under McMurray and Innovation Drive, and also ultimately to the Golden Meadows Regional Detention Pond. Sub -basins with an S prefix were not designed to be detained on -site, should sufficient capacity exist in the downstream conveyance system. Runoff from Lot 8 contributes flows to basins N-1, N-2, N-18, and S-1. As is typically the case with pad sites designed with the Harmony Safeway Marketplace, the ultimate users have made minor changes to the approved plan. Attached are exhibits illustrating the originally approved improvements and drainage basins, as well as the currently proposed improvements associated with Lot 8 and the corresponding basin revisions. As you can see, the basin revisions are minor in nature and the original intent of the engineering and drainage design has remained intact. The original runoff design calculations did account for areas of imperviousness at this location. These calculations, along with the new proposed site improvement runoff calculations, are included in this report. The portions of this project located within basins N-1, N-2, N-18, and S-I are small and the developed runoff coefficients are similar to the ones previously approved by the City of Fort Collins. When the new runoff coefficients, the revised basin areas, and the new City of Fort Collins rainfall intensity data are used to calculate the resulting flows, there 420 SOUTH HOWES, SUITE 202 / FORT COLLINS, COLORADO 80521 / 970.221.4158 / FAX 970.221.4159 are only small changes to the resulting flows from the approved design. The table below illustrates the changes that occur for the 100-year storm: Basin C; C A; (Acres) A (Acres) Qi (cfs) Q (cfs) N-1 0.91 0.97 0.50 0.54 4.1 4.1 N-2 0.98 0.76 0.28 0.33 2.5 2.5 N-18 0.80 0.58 2.41 2.17 11.4 6.6 S-1 0.99 0.80 0.90 0.91 8.0 5.2 i = original calculations As one can see, the 100-year storm estimates for Basins N-18 and S-1 were reduced from the originally approved drainage design. The estimated storm flows decreased by 4.8 cubic feet per second (cfs) in Basin N-18 and 2.8 cfs in Basin S-1. Storm flows from N-1 and N-2 remained constant with the proposed Lot 8 site plan. The storm runoff from Basins N-1 and N-2 will be collected in the proposed storm sewer inlets and will be conveyed through existing storm sewer lines to the regional detention pond. There was no net increase in flow to the existing storm sewer. The inlet calculation for Inlet N-1 is included in this report and shows that the 100-year flow depth is 0.29 feet at the inlet (ponding elevation = 4979.03 feet). As required, please see the attached surety calculations for the site's erosion control escrow amount. Please call us at 970-221-4158 if you have any questions regarding this project or require additional information. Sincerely, Northern Engineering Services, Inc Megan L. Project Engineer Reviewed b n C Aarovar, P.E. Enclosures Cc: Jim Tanner, Cahen Architectural Group P.C. File TF J i Final Drainage Report for Harmony Safeway Marketplace P.U.D. Fort Collins, Colorado Revised March 7, 1997 Prepared For: Wyatt and Associates 1865 S. 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N- Ao " AaTYNE AMET -5 �P' / %f• APLA OF oa4 Ac a 61[ Al; _ r sro [�Ew nd HARMONY ROAD (HI(;HWAY 68) LEGEND =----- EXISTING STORM SEWER PROPOSED STORM SEWER CO:====== EXISTING STORM DRAINAGE INLET EBB PROMSED STORM DRAINAGE INLET —IS PROPOSED CONTOUR ..... ..-...... EXISTWC CONTOUR CONSTRUCTION SEOUENCE - - - - WETLANDS BOUNDARY - uaKw[ YYA 1yY EPunn[p N e. cu.nss wr[ NGx 1We Ap AREA INLET FILTER IGRAVCLI I�!II.I TEMPORARY EROSION CONTROL[<aw rm uJty ucr pu 1941 STRAW BALE CHECK DAM CRD' uCDIFIEp GRAVEL DAM F' • p CURB INLET GRAVEL FILTER IETEMPORARY EROLLT ON CONTROL .. K1 iI� P_ /•°'.. DRAINAGE BASIN DELINFATON ,{�I.^••-. r.. MA.Y wI,N c.m."'r�tl ry� KE[rMN[ p eN„un i�." r�nl�i errtmri. .. DESIGN POINT nin •'•r1pnY1j SILT FENCING - �Ar�rl� BASIN LINE ON MONTE CARLO PLACE N_ "4 N-1T a� Ae M°OF PLANT OWED, TOS. N-1J 1\ 1KpRn wA1 I' ¢L 54I .,� ................ r.... J•.� CALL UTILITY NOTIFICATION S-4 CENTER OF COLORADO ,p4 AC 1-8c0g0�-9Q22-1887 OR JVY-V700 IDEIM!1" N CALL 2 BUSINESS DAYS IN AMAYCE BEFORE YOU DIG, GRACE. OR EXCAVATE FOR THE MARKING OF UNDERGROUND 60 D fi0 130 Itl0 MEMBER UTILITIES. GENERAL GRADING AND EROSION CONTROL NOTES: I ME I.T� Cr rLQT LOLLM SIV4MWAOK UIRIN 1415KIN CPAORM WTn(LrOR MOST K POTARD Ar {EAST J. KP1.1 NOOP IP MR LWSLXUC1ex pN M3 9R J WEELSO [E 111E Ex [OmRR el PAILL.11 5! LBL MSIMLE..1 OR rNTEPHOUt LAKE TN( w 1. [G5a1KRpr 5[gRN[[ AS WpICAT[p W ,I ALL Tr. MOlfCi AT,MOLUE. ,SSLOO. E. [ DARA., .,Aw1 ). �Z ... AYaw'I.AKN roe d'IOxL ONAH IrPI- ALS11. °PYi'YAOOPls'W:N°pWXlwx IK P1wrtsT oxR•Mwcl`I nilPOsnEK � n dlLrxO YmnArltx s BE, "..L. To 4 ALL SOILS EXPOSED DOME IAmL FHFL AYC( MImlN(S JKVNND Q&Me, pUF MIMLAlb16 KKM,PME rLIME. ETC.) SwLL L[ At:, W A ROIIEr(MED COMpmw °• KWDx4 , WI Al 1.. IAND l ,W% OK Y[GETATMx, DR EPEK YQAPPEN11 POSM4 "4FILL 5 YSIµLED Y SpLS Y AM(AS SLYPA Kn1RMMM., E.OA9. CRdr,M°I[ 4N SC[p/YNCxwUx KUMCAVwG~"I, )°s aS.."WPOSTYYLSS pIMRnSE AwAWO e%)OfiR°iTPRYWA2K KYM,IttD RVRLRv S IAE NWO[ r` 1r .ATLK[D WD ..1 N p I YEN vrxw0 EOWEEHLEEOMAH KR ACSmIEN m u 1D YRE WNW-uvsw[D doeax w L ."SA' DFAN[5 SIWL p[ xWFpMRN DSCDMRWN WHEN flIWML gl5r 4WAC,5 rIPMCExr YgEPIILs. AS dwx[p M[ CIF ApRT NyLWS [[vwc cEl•AKruFNr L. ALL, FE-FEMAPv ISHNSELUAKI TKNEN PEOPEOL BASUMS BE INf[CRL SNNL P. R11. OR KLDI5A CYCTED AS AEOEWAAv MWER NLx KNA)[s N NI SWI 5E OPPENTO xP P5 OSLDR Orr AMMl. WASARR IAIDD LMANM SO AS W, 1. CAUSEµM[w ROCHE .1 5�K � pMIED ROtlYAv y1R[A[(5. 2a'INO. AANO KEKIAMRL SJLF 11MTTO..1. 11ANYY SAIL SMAP C RCYNx'NRET NECT IN W.PF ALL SOIL SAFTER IM PAYS SHAM . RC SEEDED A. sAKLCNEO PT TRN'Sxw' T SwIACL RPUC.IINNL. [I PwwC[ AR FARIS THE IKKAMG, DROMPIKC. OR PE ILwG Of SONS OR AM CTKR wRRW DAFT CON SPOTS S IN ON MOY ANY MMCIC. A IwNGRMAT M4USIFEO wl@Yl SwLt BE CIGNFO IYMFDM2Lv BY THE LWIWGTW. w R ALL ArELME—HORS OF THE FALL OAMUAO A. Ch)SUN CWIWL A. AND STUDY APR IHL DEMEIDYYENI GMLL M C°°Rtl(D MTN IT ACHES TAU N IKEMNEST 11LN°EHDI ,LET rIS SUEONTCD. ASFY.A MMMLP.IH ONAONERUN GRADE M23 15F1'� [CUWCO @W µDX PLANTS TO FIIPAUSES 11 R[FIR 10 XPMiIMTµ COAHWA RIµ TO... ",OK i OM.C, 11 N. SM dHHS S-] AND 1-5 DEML➢P OLllML 4Yµ1N. Mwr KE CO4raVLD\YfA . 2i A. CITY OF FORT COLLINS, COLORADO UTILITY PLAN APPROVAL APPROVED: pWFCRM O! E44WC[RWL Mr[ CHECKED V M[ WATER WD. SEWL9 V,Rw dlt CHECKED BY NAT Srww1ATER Nlury 'I[ CHECKED BY, rAAAN AND Rfcpwlw DATE No. Revisions B Dote SE L 1 Project' BYir,t Date. ➢-a.V•.-G•T,.M'MnW'.0 HARMONY SAFEWAY MARKETPLACE t7ht D D.,pS/.,NORTHERN ENGINEERINGERVICE� 9623,03 rt... R[Wu wxxsEws o< Avu aur, cNAwL rs.a oRDm x0 ors De/rroJ '�- .e M,Ae ,W .•420SOUTH HOWE� SU[TE 02, FT. COLLMS. C'OLORADO t3U5LlSCALE: '" = so• DRAINAGE AND G (') EROSION CONTROL PLAN 970 221-4158 DESIGNER :RAC CHECI<ED BY: X%Xxx 4_I 4/97 m LOT 8 i�� 0.01 5 F. `id" INLF 1N _ET IYP r IN �i EL 4977,18 �NV. -1 4910 7'- 5' TYPE VILLAGE INN AC �Z17 AC 110011001,00119" — _ _] n �r @ h m 0 co m 0 m m m w n O'g0000 o 0 o � F _ � o v o n u. > — `Q Z m m U N u V = c0 N }s N u� O O cm v � m Q CO "_ °3Q V Uti- w o t u;, O O O O— O O O v Om O @ J 6 _u 0 m NO c -C9 u O 00 O O v U o 43 u rn m m O O N 0 0 m 6060 0 Z), f1' LO 0 IO m 0 0 O s t6 Vl � k . ri ya N � � rz LO m— m m V m O 0 N o N allw v o N N O t U U _m G A aTi 6 L }};y,m })2 ƒ�ƒ))§/ � < I «,g,m JEa,,, ~� \{ & / ƒ>/00 0 0000 > S /70 0 2 ». -a 0000 S ? ° / \«0000 2 \ a \ S 2 »{660— d 2 It 3 \)>/gq§G 2 f> ° \ \*G0q\ / ° y - R--- / ¥2,8 gggg ©% in / -2c¥2/ °--- 2 G \ S < y \ \Jq%M8 « A -,m,m 2 / 3 \ , i n \ / ,ec, �J2JG \ \ / _ - \ ) BQ Pto \0 &dodo ƒ d E�~§ \\§§j\ E e}%o S / .. -Qa,§ __,,_ >®®7a /) 0 ) Ti ��`�`^ K JJ//>Fj 2 Area Inlet Performance Curve: Lot 8 Harmony Safeway Marketplace Inlet Governing Equations: At low flow depths, the inlet will act like a weir governed by the following equation: ' where P=2(L+W) Q=3.OPH'.5 ' where H corresponds to the depth of water above the flowline At higher flow depths, the inlet will act like an orifice governed by the following equation: . where A equals the open area of the i Met grate Q = 0.67 A(2 gH ) 0.5 • where H corresponds to the depth of water abov a the centroid of the cross -sectional area (A) The exact depth at which the inlet ceases to act like a weir, and begi ns to act like an orifice is unknown. However, what is known, is that the stage -discharge curves of the weir equation and the orifice equation will cross at a certain flow depth. The two c urves can be found bel ow: 169Q`' 14.00 Weir Flow 12.00 -+-Orifice Flow 10.00 - -- -- - - a, 8,006.00 r 2.00 0.00 - 0.00 0.05 0.10 0.15 0.20. 0. Stage (ft)' If H > 1.792 (A/P), then the grate operates like an orifice; otherwise it operates like a wei r. Input Parameters: Type of Grate: (2) Neenah R-3409 Length of Grate (ft): 2.1 Width of Grate (ft): 3.5286 Open Area of Grate (ft): 5.00 Flowline Elevation (ft): 4978.740 Allowable Capacity: 80% Depth vs. Flow: Shallow Orifice Actual Elevation Weir Flow Flow Flow Depth Above Inlet (ft) (ft) (cfs) (cfs) (cfs) 0.00 4978.74 0.00 0.00 0.00 0.04 4978.78 0.22 4.30 0.22 0.08 4978.82 0.61 6.08 0.61 0.12 4978.86 1.12 7.45 1.12 0.16 4978.90 1.73 8.60 1.73 0.20 4978.940 2.42 9.61 2.42 0.24 4978.98 3.18 10.53 3.18 0.28 4979.02 4.00 11.38 4.00 0.285 4979.03 4.11 11.48 4.11 F 100-year depth 0.40 4979.14 6.83 13.60 6.83 0.50 4979.240 9.55 15.20 9.55 Inlet N is designed to intercept the full 100-year flow of 4.1 cfs up to the high point of 4979.03' / / � / \ +R \ \ \ / i s § m _ A + / e / § \ 0 0 0 0 0 i ) 2 0 o g 0 R 0 cm \ \ \ C) + ^ \ iR \ / \ / o © m + ® e e . � � P f » � M E % LU / / b ? � 0 3/ 5£% g t g / » k / k) S) g 2 . \ � / m - < / e 2 \ \ \ LU lu CO LU e 2% \ o / U c) 9LL- / 2 < £ e y 2 o e / \ / \ / It \ < / e / \ \ \ / q / / \ \ / / e < \ � � / \ \ \ \ \ / / U � ƒ t O 2 2 2//® < eƒ 5 \ \ \ � m 7 / \ / _\ / / \ \ \ / / Project Comments Sheet MENDE City of Fort CollinsSelected Departments Department: Stormwater Utility Date: April 18, 2003 Project: HARMONY SAFEWAY MARKETPLACE, PAD 8 #33-94G All comments must be received by Ted Shepard in Current Planning, no later than the staff review meeting: April 19, 2003 Note - Please identify your redlines for future reference Issue Contact: Wes Lamarque Topic: Drainage Number: 42 Created: 2/4/2003 Please revise the table with the C-factor comparisons to either be both 100-year C- factors or both 10-year C-factors. Repeat Comment 4/18/03. Number: 43 Created: 2/4/2003 The time of concentration value for basin N-18 seems a little high considering the area was reduced from the original N-18 basin. The Tc should have reduced rather than increased. Please revise. Repeat Comment 4/18/03. Topic: Erosion Control Number: 60 Created: 4/17/2003 Please provide surety calculation ( erosion escrow amount) for this site. Signature Date CHECK HERE IF YOU WISH TO RECEIVE COPIES OF REVISIONS Plat Site v/ Drainage Report Other_ Utility Redline Utility Landscape Page 1