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Home My WebLink AboutMIRAMONT VILLAGE PUD - PRELIMINARY - 54-87AH - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTRELIMINARY DRAINAGE STUDY FOR HE MIRAMONT VILLAGE P.U.D. FORT COLLINS, COLORADO PRELIMINARY DRAINAGE STUDY FOR THE MIRAMONT VILLAGE P.U.D. FORT COLLINS, COLORADO December 22, 1995 Prepared for: James Company 2919 Valmont Road, Suite 109 Boulder, Colorado 80301 Prepared by: RBD, Inc. Engineering Consultants 209 South Meldrum Fort Collins, Colorado 80521 (303) 482-5922 RBD Job No. 607-008 •1SOINC. Engineering Consultants 209 S, Meldrum Fort Collins, Colorado 80521 303/482-5922 FAX: 303/482-6368 December 22, 1995 Mr. Basil Harridan City of Fort Collins Utility Services Stormwater 235 Mathews Fort Collins, Colorado 80522 RE: Preliminary Drainage Study for Miramont Village P.U.D. Dear Basil: We are pleased to submit to you, for your review and approval, this Preliminary Drainage Study for Miramont Village P.U.D. 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, RBD Inc. Engineering Consultants Preparedly: Patricia Kroetch Project Engineer 11 9 ■ Denver 303/458-5526 Reviewed by: (UNAVAILABLE) Kevin W. Gingery, P.E. Water Resources Project Manager TABU:_ OF CONTENTS DESCRIPTION PAGE I. GENERAL LOCATION AND DESCRIPTION 1 A. LOCATION 1 B. DESCRIPTION OF PROPERTY 1 11. DRAINAGE BASINS 1 A. MAJOR BASIN DESCRIPTION 1 III. DRAINAGE DESIGN CRITERIA 1 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 2 A. GENERAL CONCEPT 2 B. SPECIFIC DETAILS 3 V. STORM WATER QUALITY 3 A. GENERAL CONCEPT 3 VI. EROSION CONTROL 4 A. GENERAL CONCEPT 4 V11. CONCLUSIONS 4 A. COMPLIANCE WITH STANDARDS 4 B. DRAINAGE CONCEPT 4 REFERENCES 5 APPENDIX VICINITY MAP 1 SITE HYDROLOGY 3 DESIGN OF INLETS AND SWALES 9 CHARTS, TABLES, AND FIGURES 14 � 0 PRELIMINARY DRAINAGE STUDY FOR MIRAMONT VILLAGE, P.U.D. FORT COLLINS, COLORADO I. GENERAL LOCATION AND DESCRIPTION A. Location Miramont Village P.U.D. (approximately 10.79 acres) is located in the southeast part of Fort Collins, bounded on the north by The Ramparts at Miramont P.U.D., by Fossil Creek on the south, and on the east by Lemay Avenue. The entire P.U.D. is a part of the Oak/Cottonwood Farms Master Plan. The Upper Meadows at Miramont First and Second Filings, and Castleridge are northwest of this area and The Ramparts at Miramont is directly north of this site. Miramont Village can also be further described as being a part of Section 1, Township 6 North, Range 69 West of the 6th Principal Meridian, Larimer County, Colorado. B. Description of Property The area described as Miramont Village P.U.D. is presently undeveloped and is being proposed as a 52 lot residential development. The property is generally sloping from north to south at approximately 5%. II. DRAINAGE BASINS Ma'or Basin Description The project site is located in the Fossil Creek Drainage Basin and is described in the report Fossil Creek Drainage Basin Master Drainageway Planning Study, prepared by Simons, Li & Associates, Inc., 1982. III. DRAINAGE DESIGN CRITERIA A. Regulations The City of Fort Collins Storm Drainage Design Criteria is being used for the subject site. 1 0 Q. Development Criteria Reference and Constraints The Overall Drainage Study for the Oak/Cottonwood Farms, prepared by RBD, Inc. May, 1992 criteria and constraints will be used in this Preliminary Drainage Study. This Overall Drainage Study has been updated to reflect all changes made to the areas considered within the scope of that report, and was completed in conjunction with the final design of Miramont P.U.D. Miramont Village P.U.D., located within the Fossil Creek Basin historically drains south to Fossil Creek. To get to the Fossil Creek Basin, the Miramont Village area will drain undetained into a water quality structure and then into Fossil Creek which lies south of this property. C. Hydrological Criteria The rational method was used to determine peak developed runoff from this site. The 2 year, and 100 year rainfall criteria, which was obtained from the City of Fort Collins, is the criteria used for this study. The rainfall criteria is included in the appendix. D. Hydraulic Criteria All calculations within this report have been prepared in accordance with the City of Fort Collins Storm Drainage Criteria. E. Variances from Criteria No variances are anticipated at this time. IV. DRAINAGE FACILITY DESIGN A. General Concept Development within Miramont Village P.U.D. will comply with the concepts presented in the Fossil Creek Drainage Basin Master Drainageway Planning Study and the Overall Drainage Study for the Oak/Cottonwood Drainage Plan. The Mail Creek Basin and the Fossil Creek Basins allow for undetained storm water runoff directly to Mail Creek and to Fossil Creek. 2 0 ■ 0 B. SRecific Details This site has been broken into seven drainage basins, six of which are on - site basins and one which is an off -site basin. The off -site basin 0-1 is an area of the Ramparts at Miramont that will sheet flow south and onto the Miramont Village site. This runoff joins the flow from on -site basin 1 and will flow into two 10 foot curb inlets. This flow is carried via 18" storm pipe to the south where runoff from basin 2 combines with this flow and is carried into basin 3 via 21" storm pipe. Runoff from basins 0-1, 1, 2, and 3 combine and flow south into Southridge Greens Boulevard. Runoff from basin 4 is collected in curb and gutter and flows southeast into Southridge Greens Boulevard. Basin 5 flows are collected in a grassed swale north of Southridge Greens Boulevard and flow southeast into the curb inlet at design point 60. Runoff from basin 6 sheet flows onto Southridge Greens Boulevard and are collected in the curb and gutter. The storm water is then conveyed west into the curb inlet at design point 60. This inlet will ultimately collect all of the runoff from the site and will convey this water to the southwest into a proposed water quality pond. From there the storm water will be released directly into Fossil Creek. V. STORM WATER QUALITY A. General Concept The water quality of storm water runoff must be addressed on all final design utility plans. The Miramont Village development is anticipating construction beginning in the fall of 1996. Best Management Practices for the treatment of storm water runoff will be determined during final design for this project. However, BMP's may include grass -lined swales, minimized DCIA, a water quality pond and installation of silt fence and gravel inlet filters during construction. All construction activities must comply with the State of Colorado permitting process for Storm water Discharges Associated with Construction Activity. A Colorado Department of Health NPDES Permit will be required before any construction grading can begin. 3 VI. EROSION CONTROL A. General Concept During final design for this site, appropriate measures will be designed to control erosion from the site. These measures to limit erosion will typically include installation of silt fence, reseeding and mulching all disturbed areas which will not be paved, and using a gravel mulch on areas which are to be paved. VII. CONCLUSIONS A. Compliance with Standards All computations within this report have been completed in compliance with the City of Fort Collins Storm Drainage Design Criteria. B. Drainage Concept The proposed drainage concepts presented in this study and shown on the final utility plans adequately provide for the conveyance of developed runoff from Miramont Village P.U.D. The concepts shown here will also allow for the development to occur and be in compliance with the Fossil Creek Basin Master Plan. This site will also be in compliance with the Overall Drainage plan for the Oak/Cottonwood Farm. :I REFERENCES 1. Storm Drainage Design Criteria and Construction Standards by the City of Fort Collins, Colorado, May 1994, revised March 1991. 2. Erosion Control Reference Manual for Construction Sites by the City of Fort Collins, Colorado, January 1991. 3. Fossil Creek Drainage Basin Master Drainageway Planning Study, by Simons, Li & Associates, Inc., August 1982. 4. Overall Drainage Study for the Oak/Cottonwood Farm and Preliminary Drainage Study for the Upper Meadow at Miramont First Filing, Fort Collins, Colorado, by RBD, Inc., May 4, 1992. 5. Final Drainage and Erosion Control Study for The Ramparts at Miramont P.U.D., by RBD, Inc. dated November, 1995. VICINTITY MAP a Ll 0 a ■ ■ VICINITY MAP SCALE: 1 "=2000' L