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Home My WebLink AboutSAVE MOR SELF STORAGE PUD FILING TWO PRELIMINARY AND FINAL - 27 93A - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTREFERENCES 1. Storm Drainage Design Criteria and Construction Standards, City of Fort Collins, May 1984. 2. Topography, Northwest Quarter Section 12, Township 7 North, Range 69 West, ARIX. 3. Drainage Report - Catholic Community Services - Tract A - Linden Tech Center, CDS Engineering Corporation, July 21, 1988. /F 3 CONCLUSIONS AND RECOMMENDATIONS After reviewing. the existing drainage information and site conditions, the following conclusions can be made. 1. Runoff from this site will fall off the centerline of each building, through a roof drain pipe, into the two -foot concrete pan in the center of access drive lanes. The pan drainage system will convey the flow to designated concentration points. 2. No on -site detention is necessary for developments within this drainage..basin. The majority of stormwater runoff`.will flow into the Coy ditch. All outlets to Coy Ditch are protected to ensure minimal.damage to the canal's embankment. The property owner is responsible for maintenance of the canals embankment as outlined in the letter of agreement. 3. No portions of this site are in the 100-year flood plain of the Poudre River. Elevations from the FIRM (July 1979). -8- iWind Erosion Wind erosion protection will consist of silt fence barriers along the east boundary of the project. The application of silt ' fence around the north and west boundaries can be significantly eliminated due to existing asphalt drives and fences surrounding the project. Earth berms (as shown on plan) will be used to reduce wind blown erosion on -site if structures are not completed within 6 weeks of beginning of construction. Water Erosion Structural Erosion control measure will consist of` -silt fence barriers, concrete foundations and application of gravel base course to drives and parking areas in the project. In the event that only portions of the project will be completed in this season, areas that receive overlot grading will receive seed and hay straw mulch at 2 tons/acre, wind erosion berms will be installed. -7- The drainage for the proposed development is divided into four basins. Basin A (1.06 Ac) collects flows form the edge of the Gustav Swanson nature area and concentrates at design point (1), a driveway cut to Linden Center Drive. Flows will follow existing curb and gutter north and,east to inlets at Linden Street. Basin B-1 (0.61 Ac) collects storm flows and drains south in concrete pans along drive aisles to a driveway cut at Linden Center Drive and design point (2). Stormwater from this area joins flows already in the curb line from design point (1). Design Point (6) reflects the peak Q's to be expected downstream of both points .of concentration, no upstream flows will be expected as Linden Center Drive falls both directions from .the high.point just south of design point (1). Calculations for street capacity on Linden Center Drive can be found in Appendix B of this report. Flows accumulated at design point oi, 6 fall eastward to a crosspan at Linden Street and turn south to drain l to existing inlets along the west flowline or overtop the existing curb head and fall directly to the Coy ditch. II Basin D-1 (0.39 Ac) storm flows collect to a pan and drain around structures to empty north into the Coy Ditch, oufalls will be 12' wide curb cuts with no curb head. The bank of the Coy ditch will be protected by rip rap slope to prevent scour and stabilize the slope during the majorstorm event (as- approved per, Save*Mor P.U.D.). Appendix B of this report shows all associated calculations for initial (10-year) and Major (100-year) storm events. EROSION CONTROL This project is located within an area of moderate wind and moderate rainfall erosion potential as identified by the City of Fort Collins wind and rainfall erodibility maps. -6- II MASTER DRAINAGE This site is located within the Poudre River drainage basin. The Coy ditch diverts flows form the Poudre River near the intersection of vine street and College Avenue with return flows entering the Poudre ' River upstream at. Linden Street bridge. No Ion -site detention is required for this site, the majority of runoff from this project will ' flow into the Coy ditch. The Coy ditch empties directly to the Poudre River approximately 1500" south of the site. Permission to drain ' stormwater runoff into Coy Ditch was agreed upon on June 20, 1980. The agreement letter is shown in Appendix A. 11- Additional agreements have been obtained (covering on -site maintenance) and both agreements are. shown in Appendix A of this report. DRAINAGE UNDER DEVELOPED CONDITIONS The development of the three storage units will significantly impact the runoff for this site. The majority of the site will be covered by buildings and asphalt driveway which increases the runoff coefficient from 0.20 to 0.95. The driveways in between each of the storage units will be inverted with a two foot concrete pan at the thalweg (low point). The entire area will be graded to allow for .positive drainage away from each storage unit. -The concrete pans will convey the runoff to various concentration points that outlet onto Linden Center Drive or the Coy ditch. A complete drainage and erosion. control plan is available in the Back Pocket of this report, please refer to this sheet for the following discussion. -5- _.TT H IM3 cJ l�Ct ® � e A A H X! l z 1AAc PARCEL D OUsnrlc w000 � COLOR4DO &SOUTHERN RAILROAD --------1 PARCEL A t t t t t PARCEL C .B ' 2.19 AC ' 1 oil am rw LINDEN CENTER DF n I n �J+90 r 'lip U �\ Iln TJ I I u I � ul I I I i I I LEGEND GRAPHIC SCALE I II \oo BASIN BOUNDARY � o ao too soo II AREA AND ACREAGE I min = 100 n. I II EXISTING CONTOUR & ELEVATION �® HISTORIC DRAINAGE SAVE*.YIOR SELF STORAGET.U.D. PHASE HISTORIC DRAINAGE SCHEMATIC z FTIr'TT14F P DRAINAGE CRITERIA This runoff from each of the subbasins was determined from the Rational Method. The Rational Formula is a widely accepted predictor of runoff from basins less than 200 acres. Flow capacities for open channels are determined from'Manning's equation. All runoff and roughness coefficients are derived form the City of Fort Collins' Storm Drainage Design Criteria and Construction Standards Manual. HISTORIC DRAINAGE Adjacent properties include a storage -unit facility (Phase 1 of this project):,.,a Catholic Community Services Center -,....and Fort Ram Nightclub. These properties will not contribute any;.'off-site flow to this project. A power substation occupies the property immediately to the west of the site. Off -site flows from this area are contained and directed to Linden Center Drive via the asphalt access road. The Coy ditch, an open irrigation channel, runs along the northern and eastern boundaries of the Linden Tech Center. This proposed development is relatively flat and supports a low grass ground cover. A runoff coefficient of 0.2 was chosen for historic conditions. As described in Save*Mor Drainage & Erosion Control (Parsons &.Associates, Inc. Sept._1993), runoff from b sin-11B" flows to the southeast onto Linden Center Drive. Basin D-1 and B-1 are part of historical basin "B" and collect to Linden Center Drive. 04= i lckorySt^..- o-a: F Conifef5l Lupine or .. lionlock St Yarroir o E - .Spurge Cir cc Qt PROJECTSITE>, ;� �} z 4 0. MaiaSt E Vine Dr Truf!!E T rti v San C Romer Sf Z• -Buckln hem St . >'y� a�dppy� y St o ' Jc ♦ N C Logan A Logan Ct P''l��s 2 E Lincoln A mi .Pj . Trb t < E rou fain iv VICINITY ;'IIAP SCALE 1" 1000' FINAL DRAINAGE & EROSION CONTROL REPORT FOR SAVE*MOR SELF STORAGE - PHASE 2 FORT COLLINS, COLORADO IINTRODUCTION The purpose of this drainage report is to provide drainage information for the development of three additional self storage units along the west side of Linden Street between Linden Center Drive and the Coy ditch. This report was prepared to provide information for on and off -site drainage. All design specifications are prepared in accordance with the City of Fort Collins Storm Drainage Design Criteria and Construction Standards. SITE DESCRIPTION The proposed site for the self -storage facility is located on Linden Center Drive and is a addition to the existing Save*Mor Self Storage P.U.D. as approved by the City of Fort Collins in July of 1993. The existing site is covered with native prairie grass. A railroad siding runs east -west through parcel B and was abandoned as part of the original Save*Mor P.U.D. The site is located in the Northwest Quarter ..... ..... . of Section 12, Township 7 North, Range 69 West of the 6th Principal Meridian, City of Fort Collins, Larimer County, Colorado. (See Figure 1) 1! This site is zoned General Industrial (I-G) and -is _in..an..area__of minimal activity. The area is permeable native grasses. Based on field verified topography, there is a railroad spur track and subgrade which forms a drainage boundary that runs east and west, at the north side of the site. Historic flows fall southerly to the back of curb and into the flowline on the north side of Linden Center Drive. -1- TABLE OF CONTENTS Introduction Site Description Drainage Criteria Historic Drainage Master Drainage Drainage Under Developed Conditions Erosion Control _. Conclusions and Recommendations Drainage and Erosion Control Figure 1 Vicinity Map Figure 2 Drainage Schematic (Historic) Appendix A Coy Ditch Discharge Agreement Appendix B Drainage Calculations Appendix C Erosion Control Calculations 1 1 3 3 5 5 6 Back Pocket 2 4 FINAL DRAINAGE & EROSION CONTROL REPORT FOR SAVE*MOR SELF STORAGE - PHASE 2 SEPTEMBER 28, 1993 PREPARED FOR: SAVE*MOR SELF STORAGE, LTD. POST OFFICE BOX 1001 TUSTIN, CALIFORNIA 92681 PREPARED BY: PARSONS & ASSOCIATES, INC. CONSULTING ENGINEERS 432 LINK LANE PLAZA FORT COLLINS, COLORADO 80524 (303) 221-2400 PROJECT NUMBER: 93.07 SAV No Text