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HomeMy WebLinkAboutDrainage Reports - 04/24/1992t PARSONS & Ia ASSOCIATES n CONSULTING ENGINEERS Final Approved Report .L Date�'�2 March 20, 1992 Mr. Glen Schlueter Stormwater Utility City of Fort Collins 235 Matthews Street Fort Collins, Colorado 80524 RE: Warren Farms Second Filing (Drainage and Erosion Control) Our Project Number: 92.07 WFS Dear Glen: Parsons & Associates, as requested by Richard Stork of Stork Development, is in the process of resubmitting Warren Farm Second Filing to the City of Fort Collins. As you may remember, Warren Farm Second Filing was originally submitted in 1986 as a 19 lot single family residential subdivision. A portion of the infrastructure improvements were constructed before the project was abandoned. It is our intent to provide the original plans and updated information requested by the City of Fort Collins to secure an approval for the project. As part of this resubmittal, we are providing additional drainage and erosion control information to meet current City of Fort Collins requirements. I have attached a map which shows the design of drainage improvements as part of the first filing. This drawing is sheet 10 of 12 sheets completed by RBD Engineering Consultants. I have also attached copies of the Final Drainage Reports for Warren Farm first and second filings. I have highlighted the area in the first filing report which indicates that the retention ponds have been sized for both areas. Erosion Control calculations are also included. We have also completed a field review of the site. It appears that the improvements designed as part of the first filing are in place and functioning properly. The area is currently covered with natural grasses and no erosion is 432 Link Lane Plaza Ft. Collins, Colorado 80524 • [3031 221-2400 :. Page 2 of 3 March 20, 1992 Warren Farms Second Filing evident on -site. In addition, the majority of the second filing utility and street improvements have been constructed. Site grading, underground utilities, utility services, and curb and gutter are existing. Improvements yet to be completed include the water taps, corner radii, some minor riprap installation, and street paving. Based on this information, I would offer the following: 1. DRAINAGE The drainage system designed for the first and second filings is constructed as designed and appears to be functioning properly. No drainage improvements are proposed to be constructed as part of the second filing at this time. Please note that a ten foot drainage easement along Lots 1, 2 and 3 in Block 2 is being provided by separate dedication to facilitate the relocation of a swale as part of the Third Filing improvements. All design and improvements for the relocation of this swale are part of the third filing. Easements for this Swale and the retention ponds will be dedicated as part of the Third Filing. 2. EROSION CONTROL The northerly eight (8) lots platted as Apollo Court include 1.94 acres. The southerly eleven (11) lots platted as Omaha Court include 2.73 acres. This area is currently covered with native grasses and shows no signs of wind or water erosion even though there has been no activity on the site for the past five years. The construction proposed for this site is to simply reshape the street subgrades and pave. Individual lot sites will be stripped as houses are constructed and no overlot grading is anticipated. A. WIND EROSION No special consideration is being given for wind erosion. The site is currently covered with native grasses, the site is only 250 feet wide from east to west in the direction of the prevailing wind, and it is estimated that the house construction will take place during the summer months, a period of low wind erosion potential. Page 3of3 March 20, 1992 Warren Farms Second Filing B. WATER EROSION The retention ponds along the New Mercer Ditch will also - act as sediment traps for the second filing. Riprap will be placed at the end of the curbs to prevent erosion in the transition of runoff flow from curb and gutters to grass -lined swales. Our inspection of the site finds that no erosion has taken place in the five years the site has been idle. All ditches and ponds appear to be sediment free at this time. In summary, we feel that this project will meet current City of Fort Collins guidelines by completing the improvements shown on the original construction drawings. As you can see, these 19 lots are in a unique transitionary state and the information I have provided should address your -drainage and erosion concerns. Please review the attached information and feel free to contact me should you have additional questions. Sincerely, ..aN511itwie/lo,\ Jeff Couch, P.E. Senior Engineer JWC/gbl Enclosures cc: Richard Stork RAINFALL PERFORMANCE STANDARD EVALUATION PROJECT: U/em Fq//ids semd, Fl 4 STANDARD FORM A COMPLETED BY: 1°4/500S e Assor Jeff Couch DATE: 3-Z6,- 9L DEVELOPED SUBBAgIN ERODIBILITY ZONE Asb (ac) Lsb (ft) Ssb (%) Lb (feet) Sb M PS M D�oc� Mob14 1•73 SSD l S7 Block Z 19Juvtfe 1 yy yy0 1.07 5-0 3Z 7Y,7 Y. c 7 ffpv Tad e 7-4 C 1 MARCH 1991 8-14 DESIGN CRITERIA EFFECTIVENESS CALCULATIONS PROJECT: Wal'itq Fgfq sfCwd Fh�,y STANDARD FORM B COMPLETED BY: pa/sov & Assoc. DATE: 3 -Zo- L Erosion Control C-Factor P-Factor Method Value Value Comment G •Serlr�nt4 f f/ap I.00 0 SO I-x,3%f Rua 1.00 ffe f01fi sf/eefs Ba{ Soil I. oo I. oo hQy in 4 fh�u si% hoe erycllal 0al. my fpD�lS�ilO Gfabj 0 CI S( d0 % Ki31in' A1 lif v/45S�s MAJOR PS SUB AREA BASIN BASIN (Ac) CALCULATIONS Block I Dlak 2 70 4. 61 Thou SW1, t4 si = . ss A«es kogj"ys 1 W41b 04 _ . 70 Ach-S Fx�s fr^; Gass = Ilu 3. NZ lf Taal - Y.67 Nres U111iotj c" (f.0 X •Si) f O.01 K .V) t 0.07 i3•V2 8 4•`7 vf(im „r of = , So Err . 91 % > 78,1 0 OK MARCH 1991 9-15 DESIGN CRITERIA CONSTRUCTION SEQUENCE PROJECT: Wa%%GI Faros Ytca d /ihi STANDARD FORM C SEQUENCE FOR 19 1z ONLY COMPLETED BY: Toff CoaC4 DATE: la qZ Indicate by use of a bar line or symbols when erosion control measures will be installed. Major modifications to an approved schedule may require submitting a new schedule for approval by the City Engineer. l992 YEAR MONTH J I F OVERLOT GRADING WIND EROSION CONTROL Soil Roughening Perimeter Barrier Additional Barriers Vegetative Methods Soil Sealant Other RAINFALL EROSION CONTROL STRUCTURAL: Sediment Trap/Basin Inlet Filters Straw Barriers Silt Fence Barriers Sand Bags Bare Soil Preparation Contour Furrows Terracing Asphalt/Concrete Paving Other VEGETATIVE: Permanent Seed Planting Mulching/Sealant Temporary Seed Planting Sod Installation Nettings/Mats/Blankets Other STRUCTURES: INSTALLED BY VEGETATION/MULCHING CONTRACTOR DATE SUBMITTED Fi'nl� Sfrpef Paving {{ ,,(( dpO st CoArtadw MAINTAINED BY APPROVED BY CITY OF FORT COLLINS ON MARCH 1991 8-16 DESIGN CRITERIA M Y PARSONS & Irk ASSOCIATES CONSULTING ENGINEERS August 4, 1986 Mr. Tom Gathman Dept. of Storm Drainage P.O. Box 580 Ft. Collins, Colorado 80522 Re: Warren Farm Second Filing Drainage Plan Dear Tom: Our office has prepared the Drainage Plan for the proposed Warren Farm Second Filing. As we have discussed previously, temporary detention ponds have been designee -as part of the First Filing to accommodate runoff from both/the First and Second Filings. The Final Drainage Report for Warren Farms Filing No. 1 , proposed by RBD, Inc., has been used as a guide in designing the Drainage Plan for the Second Filing. The purpose of this letter, then, is to present the results of the gutter flow and capacity calculations which were made by our office as part of the design of the Second Filing. These calculations show that the streets and gutters of the proposed Second Filing will have adequate capacity to carry both the 2-year and 100-year developed runoff,. based on the criteria presented in the City of Fort Collins' "Storm Drainage Design Criteria". The results of these calculations are summarized in the attached data table. Runoff leaving Meadowlark Avenue and Riva Ridge Drive will continue to be carried to the detention ponds in swales; as was proposed with the First Filing. If you have any questions, please feel. free to call me. Sincerely, Donald M. Parsons, P.B. Enclosures DMP/ln 432 Link Lane Plaza F-t. Collins, Colorado 80524 [3031 221-2400 No Text 1 A POND 'A' (RETEMTub ) REQUIRED VOLUMR• l.EEKRC FT ACTUALVOLUM6 .{.ODALREFT. Q TOr 0^ BERM • 11.0 i �dl IIOZ / ..', J: a AID t I 1% rWrole••RY OECD ,`,� `` •w. •0' )-I\ 4 I Sz IN OY �� ., ;e•i'•': � •. IN 7 6 \ 5 ati4 3 \ BL K 2 D6 :. sea DOPTAt" i, 1 / CdKReTE slbeew..LK d0.VGRT I I / `• �f� \ i t •.- FOR DRIVG R (yR8.G1ATGR / � . �e • •�. 6 ? TW$ JAW A 9 •sw.ue'(l DETwIL sF 10 2 00 /• J . W., cc 1 o \ \\\\ $ETOOTN ROAD _ EXISTING NEW MERCER CANAL POND •Br (ReTeuTow) RROYIa:eD VOLNwG: 2.lO KRa1•►r. TOI 41 %{RM 4.