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HomeMy WebLinkAboutSTONERIDGE PUD, THIRD FILING FINAL - 21 92G - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTFINAL DRAINAGE AND EROSION CONTROL STUDY FOR ONE RIDGE P.U.D. THIRD FILING FORT COLLINS, COLORADO REFERENCES 1. Storm Drainage Design Criteria and Construction Standards, by the City of Fort Collins, Colorado, May 1984, revised January 1992. 2. Erosion Control Reference Manual for Construction Sites, by the City of Fort Collins, Colorado, January 1991.. 3. Foothills Basin (Basin G) Drainage Master Plan, Fort Collins, Colorado, by Resource Consultants, Inc., February 1981. 4. Overall Drainage Study for Stone Ridge P.U.D., Fort Collins, Colorado, by RBD, Inc., July 1992. 5. Final Drainage and Erosion Control Study for Stone Ridge P.U.D. First Filing, Fort Collins, Colorado, by RBD, Inc., September 1992. 6. Final Drainage and Erosion Control Study for Stone Ridge P.U.D. Second Filing, Fort Collins, Colorado, by RBD, Inc., June 1993. 7. Overall Site Detention Pond or Stone Ridge P.U.D., Fort Collins, Colorado, by RBD Inc., March, 1994. 31 APPENDIX VICINITY MAP U) 0 < Lli m 0 LL _j o _j < fr 0 Ld 0 z . Ll. Ld (,D River m 7 "0 > 0 0 'M cr 0 z _j As 0 z V) _j 0 U_ Li- z LLJ (D Ld 11 1 -61 A 'pa 9z N C) 0 cu rr_ FINAL DRAINAGE AND EROSION CONTROL STUDY FOR STONE RIDGE P.U.D. THIRD FILING FORT COLLINS, COLORADO March 7, 1994 Prepared for: Client: The Kaplan Company 1060 Sailors Reef Fort Collins, Colorado 80525 Prepared by: RBD, Inc. Engineering Consultants 209 South Meldrum Street Fort Collins, Colorado 80521 (303) 482-5922 RBD Job No. 503-005 INC. Engineering Consultants 209 S. Meldrum Fort Collins, Colorado 80521 303/482-5922 FAX: 303/482-6368 December 6, 1993 Mr. Glen Schlueter City of Fort Collins Utility Services Stormwater 235 Mathews Fort Collins, Colorado 80522 RE: Final Drainage and Erosion Control Study for the Stone Ridge P.U.D. Third Filing Dear Glen: We are pleased to submit to you, for your review and approval, this Final Drainage and Erosion Control Study for the Stone Ridge P.U.D. Third Filing. All computations within this report have been completed in compliance with the City of Fort Collins Storm Drainage Design Criteria. We appreciate your time and consideration in reviewing this submittal. Please call if you have any questions. Respectfully, ID Inc. Engi ring Consultants ��T7erp-McEnany, E.l Project Engineer I Kevin W. Gingery, P.E. Project Manager Other Offices: Denver 303/458-5526 • Vail 303/476-6340 TABLE OF CONTENTS ESo'1RiP I1`T PAGE I. GENERAL LOCATION AND DESCRIPTION A LOCATION 1 1 B. DESCRIPTION OF PROPERTY 1 H. DRAINAGE BASINS A. MAJOR BASIN DESCRIPTION 1 III. DRAINAGE DESIGN CRITERIA A. REGULATIONS 1 B. DEVELOPMENT CRITERIA REFERENCE AND CONSTRAINTS 2 C. HYDROLOGICAL CRITERIA 2 D. HYDRAULIC CRITERIA 2 E. VARIANCES FROM CRITERIA 2 IV. DRAINAGE FACILITY DESIGN A. GENERAL CONCEPT 2 B. SPECIFIC DETAILS 3 V. EROSION CONTROL A. GENERAL CONCEPT 5 VI. CONCLUSIONS A. COMPLIANCE WITH STANDARDS 5 B. DRAINAGE CONCEPT 5 C. EROSION CONTROL CONCEPT 5 REFERENCES 6 APPENDIX VICINITY MAP HYDROLOGY STREET HYDRAULIC CAPACITY INLET DESIGN & STORM DRAIN DESIGN SWALE & CHANNEL DESIGN RIP -RAP DESIGN EROSION CONTROL CHARTS, TABLES, & FIGURES FINAL DRAINAGE AND EROSION CONTROL ,STUDY FOR STONE RIDGE P.U.D. THIRD FILING FORT COLLINS, COLORADO I. GENERAL LOCATION AND DESCRIPTION A. Location The Stone Ridge P.U.D. development is located immediately northwest of the intersection of Horsetooth Road and County Road 9. The site is bounded on the north by Pinecone P.U.D., on the west by the previous filings of Stone Ridge P.U.D., and on the south by Horsetooth Road: More specifically, the site is situate in the South 1/2 of the Southeast 1/4 of Section 29, Township 7 North, Range 68 West of the 6th P.M., Larimer County, Colorado. The site is shown on the Vicinity Map in the appendix. B. Description of Property The Stone Ridge P.U.D. Third Filing contains approximately 20 acres, more or less. This area is currently undeveloped, and consists of cultivated farmland. The existing topography is generally sloping from the west to east at approximately 0.5 percent. II. DRAINAGE BASINS A. Major Basin Description The site is located within the Foothills Basin. The drainage area is specifically described in the report entitled "Foothills Basin (Basin G) Drainage Master Plan" prepared by Resource Consultants, Inc., dated February 1981. III. DRAINAGE DESIGN CRITERIA A. Regulations The City of Fort Collins Drainage Design Criteria is being used for the subject site. B. Development Criteria Reference and Constraints The foothills Basin (Basin G) Drainage Master Plan criteria and constraints indicate that the Stone Ridge P.U.D. site is to contain a permanent on -site detention facility in the northeast corner of the site. The permanent detention pond will be required to release no more than 33 cfs of storm water runoff during the 100-year storm event. C. Hydrological Criteria The rational method was used to determine peak runoff rates from the site and from the adjacent off -site tributary areas, specifically from the First and Second Filings. The minor and major storm events utilize 2-year and 100-year City of Fort Collins rainfall criteria, respectively: The criteria is included in the appendix. D. l ,ydraulic Criteria All calculations within this study have been prepared in accordance with the City of Fort Collins Storm Drainage Design Criteria Manual. E. Variances from Criteria A variance is sought for the exceed of the minor storm gutter capacity at Design Point 25. The flow rate exceeds the gutter capacity by 0.23 cfs. The variance is requested after reasonable effort to extend the storm drainage system from the intersection of Cornerstone Drive and Blackstone Drive to Design Point 25. Further extension of the drainage system would require a bend to follow the street and avoid the other utilities proposed. Traffic on Blackstone Drive upstream from Inlet #25 would be light because of the two collector streets nearby serve other areas of the site. IV. DRAINAGE FACILITY DESIGN A. General Concert The Stone Ridge Third Filing is planned as a single family residential housing development. The Third Filing will include two phases, with 28 lots in Phase 1, and 30 lots in Phase 2. Storm water flows will generally be routed along historic drainage patterns, i.e., from the southwest toward the northeast. The Drainage and Erosion Control Plan is included in the back pocket of this report. 2 B. Specific Details Subbashis Subbasins 16 through 29 consist of the residential lots and the adjacent streets. Runoff is conveyed through the site from the First and Second Filings. The drainage from Horsetooth Road is routed onto Cornerstone Drive along with flows from Blackstone Drive that include flows from the First Filing. A retention pond system in subbasins 27 and 0-4 is connected by an equalization pipe that crosses Cornerstone Drive. A small additional flow from the future fourth filing of Stone Ridge P.U.D. is added to Fieldstone Drive as subbasin 0-5. Runoff from the south portions of the site converge at a low point in Fieldstone Drive before joining the rest of the runoff from the site and previous filings in the channel along the north property boundary. The channel ends east of the site in the permanent detention.pond that is to be constructed concurrently with development of the Third Filing. Storm Drain System Where the minor storm event produces runoff in excess of the street hydraulic capacity, a curb inlet and storm drain pipe have been placed. The storm drain system is located in Fieldstone Drive and in Blackstone Drive, and will is sized to carry the 2-year storm event. For curb inlets, the gutter capacity is based on a 6" drive -over curb within the transition section adjacent to the inlet.. For the concrete sidewalk culvert, gutter capacity is based on drive -over curb and gutter. The calculations in the -appendix indicate an inlet interception flow split where the carryover flow continues in the gutter. Several of the curb inlets are on grade and will only intercept a portion of the runoff. The inlet scheme is dependant upon the on -grade inlets intercepting the maximum possible, based on acceptable calculation procedures. The street hydraulic capacity is adequate for the 100-year storm event. The calculations in the appendix include capacity calculations for the three different street sections used in this development, i.e., 28', 36', and 70' flowline to flowline. The Final Drainage and Erosion Control Study for Stone Ridge P.U.D. Second Filing stated that when Fieldstone Drive is continued east of Kingsley Drive, curb inlets would be required on each side of Fieldstone Drive. These inlets will be installed with the Third Filing construction, and will outlet into the existing 21" ADS N12 pipe which was installed with the Second Filing. 3 Detention With the constnsction. of tb.e Third Filinsl, the permanent detention. pond �01 also be improved. This pond has been designed to accept flows from all of the developed subbasins, existing and future, within the Stone Ridge P.U.D. The temporary detention pond will be done away with, when the Fourth Filing area is developed. The improvements to the permanent pond are explained in a separate report entitled "Overall Site Detention Pond", by RBD Engineering Consultants, which was submitted in March, 1994. Off --site Flows Off -site flows from the First and Second Filings are incorporated into the design for the Third Filing. These are the only off -site flows, as the adjacent developments, Dakota Ridge and Pinecone, will not contribute any flows to the Third Filing, nor to the Stone Ridge detention pond. Channels & Swales Many of the lots will send part of their runoff toward the greenbelts behind the lots. Some of the grass swales through the greenbelts will transport the collected runoff toward the permanent channel on the north side of the site. Along the north property line, the permanent channel constructed with the First and Second Filings will be continued through the Third Filing, in subbasins 16 and 17. This continuation of the channel is designed similar to the upstream channel sections. Where the proposed bike trail connection crosses the channel, a culvert will be installed for the conveyance of 100-year flows. On the north side of Horsetooth Road, a permanent drainage Swale/retention pond in subbasin 27 will pick up flows from subbasin 5-1 and convey them to the east side of the site. A culvert will be installed under Cornerstone Drive, simply as a hydraulic equalization to increase storage capacity and provide landscaping. Horsetooth Road As mentioned in the Overall Drainage Study for Stone Ridge P.U.D., as Horsetooth Road is extended east, the hydraulic capacity may be exceeded. In anticipation of this, flows in the north gutter of Horsetooth Road are to be diverted to Cornerstone Drive. u IV. EROSION CONTROL A. General Conceit The Stone Ridge P.U.D. Third Filing lies within the Moderate Rainfall and Wind Erodibility Zones per the City of Fort Collins zone maps. The potential exists for erosion problems during construction of the Third Filing and after construction, until the disturbed ground is revegetated. According to the City of Fort Collins Erosion Control Reference Manual for Construction Sites, erosion control performance standards were calculated. Temporary seeding with mulch will be used for areas that are overlot graded. Permanent seeding with mulch will follow installation- of storm sewers and swales/channels for the greenbelt areas. Gravel filters are to be placed at all curb inlets immediately after construction. Straw bases are to be placed in all swales and channels. VI. CONCLUSIONS A. Compliance with Standards All computations within this report have been completed in compliance with the City of Fort Collins Storm Drainage Criteria. l3. Draina . Concept The 2 year runoff generated within the site will be conveyed to the detention pond by a series of storm drain pipes, streets, swales, and channels, both temporary and permanent. The 100 year runoff generated within the site will be conveyed to the detention pond by a series of. streets, pipes, swales and channels. Detention will be provided by the construction of the detention pond at the northeast corner of the Stone Ridge parcel. C. erosion Control Cqn . Ii Tile erosion control performance standard was calculated, and appropriate measures have been taken to control erosion from the site according to the performance standard as shown in the appendix. The erosion control measures are consistent with the City of Fort Collins Erosion Control Reference Manual for Construction Sites. e