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Home My WebLink AboutEAST DRAKE TERRACE OFFICE PARK PUD - 58 93 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTEast Drake Terr'- P.U.D. Drainage Report page 3 V. EROSION CONTROL It is anticipated that the proposed improvements for the East Drake Terrace P.U.D. will be completed by the end of November 1993. Lot grading is to begin after approval, with construction of utilities, drainage structures and appurtenances, and parking areas to follow. Temporary erosion control measures consist of gravel filters to be placed around the three inlets as shown on the attached Drainage Plan. The filters should be monitored by the contractor during construction and maintained as necessary. Permanent vegetative erosion control will be used in conjunction with landscaping. Permanent revegetation of off -site areas disturbed by construction will be the responsibility of the contractor. Seed will be applied by drilling and protected by crimped straw mulch. Straw shall be applied at a rate of two tons per acre (minimum). East Drake Terr;•1 P.U.D. Drainage Report i page 2 1 III. HISTORIC DRAINAGE All of the Historical Runoff from the site flows to the east through the apartment complex and northeast to Marquette Street. It then makes its way into a detention basin originally designed for the overall Cottonwood P.U.D. The basin was designed to detain the 50 yr. return period storm. No off -site drainage flows across this site. The Rational Method was used to predict the peak runoff. The runoff coefficient for pasture land (C = 0.20) was used to obtain the 2 and 100 year peak storm water flows at the concentration point of the site. Table A shows the results of peak historical runoff calculations (formulas used are shown on Table A Calculations). IV. PROPOSED IMPROVEMENTS The development of the site would include 7 general office buildings, approximately 41,000 square feet of asphalt -paved concrete -curbed parking with islands, reconstructing the 24 ft. wide access drive, and landscaping. Existing water and sanitary sewer structures and piping will be utilized to the extent possible with new water and sanitary sewer constructed as needed to service the buildings (see plans for locations of proposed service connections). Any existing sanitary sewer manholes not utilized in the new development will be removed. Existing water and sanitary sewer piping not used will be abandoned in place except where such piping is under a proposed building in which case the piping shall be removed. When developed, the runoff from the site will be directed to inlets located near the center of each parking area. The 100 yr. storm will be detained to the historic 2 yr. storm runoff rate on site within the parking areas. Each inlet will have an orifice plate installed over the discharge pipe to limit the discharge rate. Storm water will then be piped from these inlets into the existing 48" C.M.P. storm sewer pipe located on the site. I Preliminary Drainage Report j for EAST DRAKE TERRACE P.U.D. Fort Collins, Colorado September, 1993 I. GENERAL This report summarizes the results of a storm drainage study conducted for the proposed development of the East Drake Terrace P.U.D. to be located in the Southeast quarter of Section 24, Township 7 North, Range 69 West of the 6th Prime Meridian, in the City of Fort Collins, County of Larimer, Colorado. Methods outlined in the City of Fort Collins, Colorado Storm Drainage Design Criteria and Construction Standards Manual were used in the calculations for the storm water runoff portion of this study. The Rational Method was used to estimate peak storm water runoff from the site. Summary calculations and other supporting material are contained in an appendix to this report. II. SITE DESCRIPTION The proposed East Drake Terrace P.U.D. is a 7 building general office complex, being'1.84 acres in size. It is.located on Tract B of the Cottonwood P.U.D. The site is bounded on the north by Marquette Drive, on the east by a portion of Cottonwood Subdivision, on the south by Drake Road, and on the west by Stover Street. The existing site is an open field covered by medium size I native grass on a one foot depth of silty clay with an existing 24 ft. wide asphalt drive connecting Stover Street with the apartment complex to the east. Existing grade is approximately 1.6% from j west to east. ` There are both water and sanitary sewer services currently on the site. A 48" C.M.P. storm sewer pipe runs through the property near the north and east property lines. Existing 3-phase power is located on the east side of the property. This property is located in the Spring Creek Storm Drainage Basin. ° o N I � Dine L / ' v da l Porker St o d Q. v or- Ei j6\� ; )/ ' i L AI ert Avea W. AIpCt^ � YW e e down _n u oo �,% E Z Stuart 3.b tnS t In an Windows m n E. Stuart St. Johnson �SAring!rbr " C kee �Commarx 6 Dr. c he enne 0�' v Indian EQ• c c,o/ i _ y Summit r O pr VI C O m Cheyenne o ; a c E o CI. a` o 06Arthur-E t !f Dr. v v > ` N a tone " (i U) c•. .01 oNrN N 00 Q y N 2 Dr c art Dartmouth y v Tr it f/ Dr. ¢ e o4/h7 c Cis., Niagvro a�. Rutgers Av ��' —� hippew Ct. 11 a e Ln. O o r`o 7 O L- a: 3 V o Columbia Y o t o TeakM Q N ` a i Yale v umbia oYafe Wa G Corn II Ave Cambrid N Rd Parkwood 9� r. Dr N CiHeadherWoo a o n V °�e r w n A in iff CL t Sewood c Queens E L n. N d Cf. G o PARKW00 Princeton d' U d LAKE O r 0 o J Baylor St. °7 � o o�s:CT m' Prince on Rd Cti � ui rn va o In N N N = d L v in a c t nderb Dr. o P c Heather Dr. W. Dr. E. i k1en St. u r«a Ct. O U Q a U Mae St. o Strac an D !s W an larvard Rut 1 �a Edinburgh Ct. gg o St- N AlexanderCt. 9 0 6x or Del Ciao Rd. Oxford Ln, r _ �� G S, Cortez �- c qi° a cf. Dr F n �P 'i' N o U c ~ Linda °�; Q^ P �o• � Swallow P. —71E `o E. Swallow Rd c_ v Ct. StratboroughLn ■ � 'o a v 3 L. vU _ t f m m PdrkV�n Q m� VICINITY MAP September 2, 1993 Mr. Glen Schleuter Stormwater Utility City of Fort Collins 235 Mathews P.O. Box 580 Fort Collins, Colorado 80522-0580 I re: East Drake Terrace P.U.D. 1 Preliminary Drainage Project No 9321.00 Dear Glen: Northern Engineering is pleased to submit this report of a stormwater investigation for the .East Drake Terrace P.U.D. It represents a preliminary study of existing and proposed runoff characteristics of the project site. we would like to thank you for your valuable input during the research and review phases of this study. If you have any i questions or comments as you review this report, please feel free to contact me at your earliest convenience. Sincerely, RTHERN ENGINEER Terry P. McEnany Project Engineer Reviewed by: Michael F. Jones, P.E. Project Manager ICES, INC. I Preliminary Drainage Report for EAST DRAKE TERRACE P,U,D. Fort Collins, Colorado September, 1993 prepared by NORTHERN ENGINEERING SERVICES, INC. 420 S. Howes, Suite 106 Ft. Collins, Colorado 80521 Project No. 9321.00