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HomeMy WebLinkAboutUNITED WAY HOUSING SERVICES DAY CENTER - PDP - 30-06 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTsediment at drainage structures. Each of these measures is described below and shall be utilized by the developer and/or the contractor during any construction activity occurring at this site. B. General Erosion and Sediment Control Measures Minimizing Soil Exposure: Where practical, the construction area and duration of soil exposure should be kept to a minimum. All other areas should have a good cover of vegetation or mulch. Grading should be completed as soon as possible after it is begun. A temporary cover crop, a permanent vegetative cover crop or other landscaping should be established in disturbed areas. Re -vegetation may consist of native grasses, lawn grasses or various winter wheat. Decorative rock, flower gardens or shrubs may also be utilized in the final landscaping to cover the soil. Re -seeded areas should be mulched with straw or hay to protect exposed soil until vegetation is established. Controlled Runoff Across Exposed Areas: Where practical, construction may I include constructing temporary swales to intercept and direct storm water around exposed areas. Swales can be constructed to control surface water, which collects on exposed areas and prevents gross erosion in the form of I gullies. Riprap, straw bale dikes or other temporary erosion control devices may be installed to control storm water velocities across exposed areas. I Sediment Control: Temporary and/or permanent sediment control devices may be installed at the major drainage structures and flow concentration points shown on the Drainage Exhibit. Such structures shall be used to I intercept and trap sediment once it is produced and prevent it from being conveyed offsite onto downstream property. ' C. Erosion and Sediment Control Plan The following summarizes the overall erosion control plan for this project. ' The details will be shown on the construction drawings. 1. Silt fence will be utilized downstream of construction activity before it ' exits the site. Vehicle tracking control will be utilized at the site exit. 2. Other erosion control measures will be used as necessary to help minimize ' erosion for this project. VII. References Final Drainage Report for Conifer Industrial Park" as prepared by Stewart & Associates, Inc., dated December 28, 1992. 4 top that drains directly into the detention pond. Sub -basin F consists of the landscape area located between the building and Blue Spruce Drive. Sub - basin F will sheet flow to Blue Spruce Drive. According to the "Final Drainage Report for Conifer Industrial Park" as prepared by Stewart & Associates, Inc., dated December 28, 1992, the combined total allowable release rate for Lots 2 and 3 is 0.36 cfs. The undetained 100-year runoff (Sub - basin F) is 0.30 cfs. The release rate for the detention pond is the allowable total flow of 0.36 cfs minus the undetained runoff of 0.30 cfs or 0.06 cfs. V. Conclusions A. Compliance with Standards All storm drainage calculations followed the guidelines provided by the City of Fort Collins Storm Drainage Design Criteria. B. Drainage Concept The drainage system has been designed to convey the runoff to the designated inlets in an effective manner as safe as possible. The allowable release rate for our detention pond was 0.06 cfs. The 100-year water surface elevation of 65.16 feet and the top of berm is 66.5. The total required 100-year detention volume for the site is 13,180 cubic feet. The water quality volume that is required is 1330 cubic feet. Adding the water quality volume to the detention volume yields a total required volume of 14,509 cubic feet. In the event the pond is overtopped, runoff will be directed via the northeastern driveway which will overflow onto Blue Spruce Drive. Blue Spruce Drive is located within the 100 year flood plain of Dry Creek. VI. Erosion and Sediment Control This section describes methods recommended to control wind erosion, soil erosion and sediment from storm runoff during and after the construction of drainage structures and site grading. This development of erosion control criteria establishes the methods and guidelines used to perform the erosion analysis and develop the erosion control plan. A. Discussion The clearing and stripping of land for site grading, overlot grading or for the construction of drainage structures and swales may cause high -localized erosion rates with subsequent deposition and damage to offsite properties. Uncontrolled, such erosion could destroy the aesthetic and practical values of individual sites and cause damage to downstream property. " In general, erosion and sediment control measures may consist of minimizing soil exposure, controlling runoff across exposed areas and controlling 3 4 B. Development Criteria Reference and Constraints The developed site will convey runoff to the southeastern detention pond in Lot 3 in a safe and effective manner. C. Hydrological Criteria In accordance with the Fort Collins' policy, a minor and major storm for the Fort Collins area is identified as the 2-year and 100-year storms, respectively. A major storm for the Fort Collins area has a recurrence interval of 100 years and a total rainfall depth of 3.67 inches for a 2-hour design storm, with a peak intensity of 9.95 in/hr. These storms have been used as a basis for planning and system design. The peak flow rates for design points have been calculated based on the rational method as described in the Storm Drainage Design Criteria, with storm duration set equal to the time of concentration for each sub -basin. D. Hydraulic Criteria The majority of the runoff produced by the site will be conveyed to the detention pond located southeast of the site. Most of the runoff produced by the site will be conveyed to the proposed inlets or sidewalk culverts within the development. The inlets were sized for the 100-year storm along with their corresponding storm pipes. IV. Drainage Facility Design A. General Concept Runoff from Sub -basins A, B, C, D, and E will contribute runoff to the detention pond. These sub -basins consist of rooftop, pavement and landscape. Sub -basin F, located along the eastern boundaries of this site, consists of mostly landscape areas with a small amount of sidewalks. The runoff from this sub -basin flows as sheet flow to Blue Spruce Drive. B. Specific Details Sub -basin A which includes the northern parking lot and a portion of the proposed building roof top, will drain to a 5-foot Type R inlet. From there, the runoff will be conveyed via a storm pipe, southerly to the detention pond. Sub -basin B consists of sidewalks and an outdoor storage area that will drain to a proposed area drain and into the detention pond. Sub -basin C consists of the western parking lot and will drain through a sidewalk culvert and directly into the detention pond. Sub -basin D consists of the majority of the building roof drainage and will drain via underground roof drain pipes to the storm pipe from Sub -basin A. Sub -basin E consists of the landscape area and roof 2 I. General Location and Description A. Location Lots 2 and 3 of Conifer Industrial Park are located in Section 1, Township 7 North, Range 69 West of the 6th P.M., City of Fort Collins, County of Larimer, State of Colorado. The site is bounded on the south by Conifer Street and on the east by Blue Spruce Drive. Vacant land is immediately west of the site. B. Description of Property The site to be developed consists of approximately 1.41 acres and is generally sloping at approximately 1 % easterly/southeasterly although several portions of the site are fairly flat. The site currently consists of native vegetation and disturbed ground. The site is to be developed into one commercial building with associated parking and driveways. Il. Drainage Basins and Sub -Basins A. Major Basins Description The site is currently located in the Dry Creek Basin as described in the City of Fort Collins Master Stormwater Basin Map. All of the runoff from the site has been included in the "Final Drainage Report for Conifer Industrial Park" as prepared by Stewart & Associates, Inc., dated December 28, 1992. Within said report, the 2-year release rate was determined for this site. The release rate for new development within the Dry Creek Basin is the 2 year storm. Stewart's study designated this site to have a detention pond on the southeast corner and to provide over -detention for the undeveloped land to the west and north. From discussion with the City of Fort Collins staff, we concluded that the required detention storage on this site will only be for this site and will not include detention for the offsite vacant land. B. Sub -Basin Description In the developed condition, there will be six subbasins, five of which contribute runoff to the southeastern detention pond. One sub -basin is undetained with runoff directed to Blue Spruce Drive. III. Drainage Design Criteria A. Regulations The design criteria for this study are directly from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards Manual. TABLE OF CONTENTS SECTION I - GENERAL PROJECT LOCATION AND DESCRIPTION Page No. Location Description of Property SECTION II - DRAINAGE BASINS & SUB -BASINS Major Basin Description Sub -Basin Description SECTION III - DRAINAGE DESIGN CRITERIA Regulations 1 Development Criteria Reference and Constraints 2 Hydrological Criteria 2 Hydraulic Criteria 2 SECTION IV - DRAINAGE FACILITY DESIGN General Concept 2 Specific Details 2 SECTION V — CONCLUSIONS Compliance with Standards 3 Drainage Concept 3 SECTION VI — EROSION AND SEDIMENT CONTROL Discussion 3 General Erosion and Sediment Control Measures 4 Erosion and Sediment Control Plan 4 SECTION VII — REFERENCES 4 EXHIBIT A - Drainage and Erosion Control Plan PROFESSIONAL ENGINEER'S CERTIFICATION I hereby certify that this Final Drainage Plan and Report for Lots 2 and 3, Conifer Industrial Park was prepared by me or under my direct supervision in accordance with the provisions of the City of Fort Collins Storm Drainage Design Criteria for the owners thereof. Loonan and Associate "' cir'i, Vanes R. I Registered State of Cc .Glom" & 0461oc. 90C. 1435 Z &"d4f d Ae. zm4ee4a, ed m5v (970) 461-0550 57WZ (970) 461-0551 October 3, 2006 City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, CO 80526 RE: LOTS 2 AND 3 OF CONIFER IND USTRL4L PARK Dear Sirs: Loonan and Associates, Inc. is pleased to submit this Final Drainage Report and Plan for the proposed Lots 2 and 3 of Conifer Industrial Park site, which is located at the southwest corner of the intersection of Conifer Street and Blue Spruce Drive. Please review this Final Drainage Report and Plan at your earliest convenience. We look forward to your comments and ultimate approval of the Final Drainage Report. Please feel free to contact me at (970) 461-0550 if you have additional questions. Sincerely, ,C'wN" aKd aaxlatea, Sac. James R. Loonan FINAL DRAINAGE AND EROSION CONTROL STUDY FOR LOTS 2AND 3 CONIFER INDUSTRIAL PARK PREPARED FOR: ARCHITECTURAL WEST, LLC DATE: OCTOBER 2006 PROJECT NO.205 CONSULTING ENGINEER: LOONAN AND ASSOCIATES, INC. 1435 N. CLEVELAND AVE. LOVELAND, CO 80538