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Home My WebLink AboutSTERLING HOUSE - PRELIMINARY/FINAL PUD - 5-97 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTNo Text APPENDIX A LOCATION MAP DRAINAGE AND EROSION CONTROL REPORT STERLING HOUSE - FORT COLLINS 7. REFERENCES 1. City of Fort Collins, "Storm Drainage Design Criteria and Construction Standards," (SDDCCS), dated May 1984. 2. Urban Drainage and Flood Control District, "Urban Storm Drainage Criteria Manual," Volumes 1 and 2, dated March 1969, and Volume 3 dated September 1992. 11 I, Bucher, Willis & Ratliff Corporation juu' a".n... WPmRmvM 1PM DRAINAGE AND EROSION CONTROL REPORT STERLING HOUSE - FORT COLLINS 6. MISCELLANEOUS Variances There are no variances requested with the development of the University Center PUD. Maintenance Agreements The developer will be responsible for the maintenance of all temporary drainage structures. 10 Bucher, Willis & Ratliff Corporation ss�skn.oi�we nra� wwnv:nrris d DRAINAGE AND EROSION CONTROL REPORT STERLING HOUSE - FORT COLLINS During the performance of the work or any operations appurtenant thereto, the Contractor shall carry out proper efficient measures wherever and as necessary to reduce dust nuisance, and to prevent dust nuisance, and to prevent dust which has originated from his operations from damaging crops, orchards, cultivated fields, and dwellings, or causing a nuisance to persons. The Contractor will be responsible for any damage resulting from dust originating from his operations. Tracking Mud on City Streets Wherever construction vehicles access routes or intersect paved public roads, provisions must be made to minimize the transport of sediment (mud) by runoff or vehicles tracking onto the paved surface. Stabilized construction entrances are required per the detail shown on the Plan, with base material consisting of 6" coarse aggregate. The contractor will be responsible for clearing mud tracked onto city streets on a daily basis. Maintenance All temporary and permanent erosion and sediment control practices must be maintained and repaired as needed to assure continued performance of their intended function. Maintenance is the responsibility of the contractor. Permanent Stabilization A vegetative cover shall be established within one and one-half years on disturbed areas and soil stockpiles not otherwise permanently stabilized. Vegetation shall not be considered established until a ground cover is achieved which is demonstrated to be mature enough to control soil erosion to the satisfaction of the City and to survive severe weather conditions. Erosion control calculations, cost estimate, and schedule is included in the Appendix of this report. G Bucher, Willis & Ratliff Corporation /�V411 A11WPTAP\DMMAPf3T' I DRAINAGE AND EROSION CONTROL REPORT STERLING HOUSE - FORT COLLINS 11 5. EROSION CONTROL Introduction This section represents the Erosion Control Report for the Sterling House and was prepared to meet the regulatory requirements of the City of Fort Collins, Colorado. This report was �i prepared following the guidelines and regulations within the SDDCCS Manual. General Description The proposed improvements cover the entire site, which totals 3.15 acres. The general topography of this site consists of undisturbed soil with native vegetation. The slopes range from 1 to 2 percent. Soil Description In accordance with the Soil Conservation Service's (SCS) "Soil Survey of Fort Collins Area, Colorado," the soils on -site consist of the following: Rainfall Wind Hydrologic Soil Designation Erodibility Zone Erodibility Zone Soil Group Sandy lean clay Slight to Moderate Slight to Moderate C Erosion and Sediment Control Measures Erosion and Sedimentation will be controlled on -site by the use of silt fence, gravel construction entrance, and inlet protection (straw bale filters). The measures are designed to limit the overall sediment yield increase due to construction as required by the City of Fort Collins. Dust Abatement 8 Bucher, Willis & Ratliff Corporation �y�sun onwwn,mornaurm ' 11 DRAINAGE AND EROSION CONTROL REPORT STERLING HOUSE - FORT COLLINS 4. RUNOFF DETENTION AND RELEASE The site will contain two interconnected ponds, acting as one pond, located on the south and southeast side of the property. The pond release will be controlled by a restriction plate located in the southeast pond. The release rate is equal to the 2-year historic in accordance to SDDCCS (Ponds Release = 0.82 cfs). Calculations are included in the Appendix of this report. Bucher, Willis & Ratliff Corporation �j�Y4n.4�\ WFWRTOANNlPL3T!' 7 DRAINAGE AND EROSION CONTROL REPORT STERLING HOUSE - FORT COLLINS IHydrologic Analysis of the Proposed Drainage Conditions The Rational Method was used to determine both 10-year and 100-year peak runoff values for each Sub -basin. Runoff coefficients were assigned utilizing Table 3-2 of the SDDCCS Manual. As stated above, the Rational Method was used for all hydrologic analyses for the project site. The Rational Method utilized the SDDCCS equation: Q=CfCIA where Q is the flow in cfs, A is the total area of the basin in acres, Cf is the storm frequency adjustment factor, C is the runoff coefficient, and I is the rainfall intensity in inches per hour. The frequency adjustment factor, Cf is 1.0 for the initial 10-year storm and 1.25 for the major 100-year storm. The appropriate rainfall intensity information was developed based on rainfall intensity duration curves in the SDDCCS Manual. In order to utilize the rainfall intensity curves, the time of concentration is required. The following equation was used to determine the time of concentration: t= ti+tt where t, is the time of concentration in minutes, ti is the initial or overland flow time in minutes, and tt is the travel time in the ditch, channel, or gutter in minutes. The initial or overland flow time is calculated with SDDCCS Manual equation: t,=[1.87(1.1 - C Cf )L0.5]/(S)0.33 where L is the length of overland flow in feet (limited to a maximum of 500 feet), S is the average slope of the basin in percent, and C and Cf are as defined previously. All hydrologic calculations associated with the redeveloped sub -basins are attached in the Appendix of this report. ri I Bucher, Willis & Ratliff Corporation a�sun w�wrm�Ponnnu�rrm DRAINAGE AND EROSION CONTROL REPORT STERLING HOUSE - FORT COLLINS 0 3. DEVELOPED FLOWS OMethod The Rational Method was used to determine both the 10-year and 100-year developed flows for each sub -basin. A detailed description of the hydrologic analysis is provided later in this section. Off -site Flows Currently the swale that flows from north to south along the east side of the Miramount Q Fitness and Tennis Center discharges across the southwest corner of the proposed Sterling House property to Rule Drive. It is our understanding that this swale should have discharged directly to Rule Drive from the fitness center property without impacting adjacent properties. We are in the process of contacting the property owner to resolve the situation. aOn -site Flows Drainage within the developed area will surface flow to inlets and detention areas. All a grading has been designed to carry flows away from structures to the proposed drainage facilities. A qualitative summary of the drainage patterns within each developed sub -basin is provided in the following paragraphs. Detention and release rates are described in Section 4, 'Runoff Detention and -Release". Runoff from Sub -basin A is conveyed by surface flow to inlets IN-2 and IN-3 and piped to the pond. aRunoff from Sub -basin B is conveyed by surface flow to the inlet IN-1 and piped to the pond. ORunoff from Sub -basin C is conveyed by the surface flow directly to the pond. Runoff from Sub -basin D is conveyed by surface flow and released to the pond through a curb opening and trench drains. 11 5 Bucher, Willis & Ratliff Corporation �wun onwnzxmouwarrmc DRAINAGE AND EROSION CONTROL REPORT STERLING HOUSE - FORT COLLINS 2. HISTORIC (EXISTING) DRAINAGE Historical drainage on site has been sheet flow from the northwest to the southeast with discharge occurring at Rule Drive. The discharge then flows along the north side of Rule Drive to an existing inlet at S. Lemay, then into the swale to the south along S. Lemay Drive. 4 Bucher, Willis & Ratliff Corporation 4:�94n41� WP�AFPOMM�ITFT: DRAINAGE AND EROSION CONTROL REPORT STERLING HOUSE - FORT COLLINS Where applicable, the criteria established in the "Urban Storm Drainage Criteria Manual' (UDFCD), 1984, developed by the Denver Regional Council of Governments, has been utilized. Master Drainage Basin This site falls within the Oak Cottonwood Farm ODP - McClelland Basin. The overall drainage report was prepared bythe Sear -Brown Group. 3 Bucher, Willis & Ratliff Corporation Z�wnm�wemiwouwenrrn DRAINAGE AND EROSION CONTROL REPORT STERLING HOUSE - FORT COLLINS 1. INTRODUCTION Project Location The proposed Sterling House subdivision is a tract of land situated in the Northeast Quarter of Section 1, Township 6 North, Range 69 West of the Sixth Principal Meridian, City of Fort Collins, County of Larimer, State of Colorado. The site is bounded on the.west by an existing commercial development, Miramount Fitness and Tennis Center, on the north by the Evangelical Covenant Church, on the south by Rule Drive. The area to the east is vacant. ® Site Characteristics The general topography of the site consists primarily of undisturbed soil with native vegetation. The slopes range from 1 to 2 percent. I Soils The soils for this site are comprised of the sandy lean clay. The source for this soil data is the Geotechnical Engineering Report prepared by Terracon Consultants Western, Inc., dated December. 3,1996. Purpose and Scope of Report This report defines the proposed drainage and erosion control plan for the proposed Sterling House assisted care living facility, including consideration of all on -site and tributary off -site runoff. Design Criteria This report was prepared to meet or exceed the submittal requirements established in the City of Fort Collins' "Storm Drainage Design Criteria and Construction Standards" (SDDCCS), dated May 1984. Runoff computations were prepared for the 10-year and 100- year storm frequency utilizing the rational method. 2 Bucher, Willis & Ratliff Corporation P\94301\ WpZAPDWMIPl3TC DRAINAGE AND EROSION CONTROL REPORT STERLING HOUSE - FORT COLLINS CERTIFICATION I hereby certify that the Drainage and Erosion Control Report for Sterling House, Fort Collins was prepared by me or under my direct supervision in accordance with the provisions of the City of Fort Collins STORM DRAINAGE CRITERIA and CONSTRUCTION STANDARDS for the owners thereof. Daniel C. Blankenship, P.E. Colorado Registration No. 28198 For and On Behalf of Bucher, Willis & Ratliff Corporation 1 Bucher, Willis & Ratliff Corporation 1j19Nll.onw MD�m.' DRAINAGE AND EROSION CONTROL REPORT for UNIVERSITY CENTER PUD TABLE OF CONTENTS CERTIFICATION.................................................................. 1 1. INTRODUCTION........................................................... 2 2. HISTORIC (EXISTING) DRAINAGE .......................................... 4 3. DEVELOPED FLOWS ....................................................... 5 4. RUNOFF DETENTION AND RELEASE ...................................... 7 5. EROSION CONTROL....................................................... 8 6. MISCELLANEOUS......................................................... 10 7. REFERENCES............................................................. 11 APPENDIX A - LOCATION MAP APPENDIX B - HYDROLOGIC CALCULATIONS APPENDIX C - EROSION CONTROL POCKET - DRAINAGE, GRADING, AND EROSION CONTROL PLAN DRAINAGE AND EROSION CONTROL REPORT STERLING HOUSE FORT COLLINS, COLORADO Prepared For: BCI CONSTRUCTION 453 SOUTH WEBB ROAD, NO. 500 WICHITA, KS 67207 Prepared By: BUCHER, WILLIS & RATLIFF CORPORATION 1743 Wazee Street, Suite 200 Denver, CO 80202 (303) 292-5056 January 15,1997 H! BUCHER, Wllll & RaTllff M® CORPORATION