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HomeMy WebLinkAbout5TH FILING OF QUAIL HOLLOW SUBDIVISION - FINAL - 46-89D - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTFINAL DRAINAGE STUDY FOR THE QUAIL HOLLOW FIFTH FILING FINAL DRAINAGE STUDY FOR THE QUAIL HOLLOW FIFTH FILING March 29, 1991 Prepared for: d. Jensen Enterprises 2601 Yorkshire St. Fort Collins, Colorado 80526 Prepared by: RBD, Inc. Engineering Consultants 2900 South College Avenue Fort Collins, Colorado 80525 (303) 226-4955 RBD Job No. 014-037 ngwINC Engineering Consultants 2900 South College Avenue Fort Collins, Colorado 80525 303/226-4955 FAX: 303/226-4971 March 29, 1991 Ms. Susan Hayes City of Fort Collins Utility Services Stormwater 235 Mathews Fort Collins, Co. 80522 RE: Final Drainage Study for the Quail Hollow Fifth Filing RBD Job. No. 014-037 Dear Susan: We are pleased to submit to you, for your review and approval, this Final Drainage Study for the Quail Hollow Fifth Filing. All computations within this report have been completed in compliance with the City of Fort Collins Storm Drainage Design Criteria. We are aware that an update to the Spring Creek SWMM computer model, with the proposed temporary detention ponds no. 1 and 2, will be required before the review process is completed. The SWMM computer model will be submitted at the time in which we address your review comments. Thank you for your time and consideration of this submittal. Please call if you have any questions. Respectfully, RBD Inc. Engineering Consultants tea`` a���.••••'�u°�' _ c.S .� 24766 Kevin W. Gingery, P.E. D,r•'•• ; 4 Project Engineer '.,see �n�unaunu�u� CC: Mr. Dan Jensen - d. Jensen Enterprises Other offices: Denver 303/778-7338 • Vail 303/476-6340 • Colorado Springs 719/598-4107 - Longmont 303/678-9584 TABLE OF CONTENTS DESCRIPTION PAGE I. GENERAL LOCATION AND DESCRIPTION A. LOCATION 1 B. DESCRIPTION OF PROPERTY 1 II. DRAINAGE BASINS AND SUB -BASINS A. MAJOR BASIN DESCRIPTION 1 B. SUB -BASIN DESCRIPTION 2 III. DRAINAGE DESIGN CRITERIA A. REGULATIONS 2 B. DEVELOPMENT CRITERIA REFERENCE AND CONSTRAINTS 2 C. HYDROLOGICAL CRITERIA 3 D. HYDRAULIC CRITERIA 4 E. VARIANCES FROM CRITERIA 4 IV. DRAINAGE FACILITY DESIGN A. GENERAL CONCEPT 4 B. SPECIFIC DETAILS 4 V. EROSION CONTROL A. GENERAL CONCEPT 7 B. SPECIFIC DETAILS 7 VI. CONCLUSIONS A. COMPLIANCE WITH STANDARDS 8 B. DRAINAGE CONCEPT 8 REFERENCES 9 APPENDIX A VICINITY MAP 1 FILING NO. 5 HYDROLOGY 2 DETENTION PONDS NO. 1 & 2 HYDROLOGY 7 DETENTION PONDS NO. 1 & 2 SIZING 15 DETENTION PONDS NO. 1 & 2 HYDRAULIC DESIGN 22 DESIGN OF INLETS, STORM SEWER AND OVERFLOW SWALE INTO POND NO. 2 32 DESIGN OF SWALE FROM YORKSHIRE ST. TO POND NO. 1 35 RIPRAP DESIGN 39 SPRING CREEK FLOODPLAIN DATA INFORMATION 43 APPENDIX A CONT. PAGE DESCRIPTION 46 EROSION CONTROL 49 CHARTS, TABLES AND FIGURES APPENDIX B QUAIL HOLLOW FILINGS 4 THRU 7 PRELIMINARY 1 DRAINAGE PLAN SHEET 1 OF 2 QUAIL HOLLOW FILINGS 4 THRU 7 PRELIMINARY 2 DRAINAGE PLAN SHEET 2 OF 2 BURNS RANCH AT QUAIL RIDGE PRELIMINARY 3 DRAINAGE PLAN FINAL DRAINAGE STUDY FOR THE QUAIL HOLLOW FIFTH FILING I. GENERAL LOCATION AND DESCRIPTION A. Location The Quail Hollow Subdivision is located east of the southerly extension of Overland Trail and south of Yorkshire and Michener Streets in southwest Fort Collins, Colorado. The site is shown on the Vicinity Map in Appendix A. More particularly, the site is described as Quail Hollow, Fifth Filing, and is situated in the Northwest 1/4 of Section 28, Township 7 North, Range 69 West of the Sixth P.M., City of Fort Collins, Larimer County, Colorado. B. Description of Property The Quail Hollow Fifth Filing contains 18.7 acres more or less of which all of the area is currently undeveloped and being proposed for residential development. The majority of the property has consisted of cultivated farm land. Topography at the site is generally sloping from northwest to southeast at approximately 1.2%. A tributary to Spring Creek traverses through the site from a northwest to southeasterly direction. Within this tributary to Spring Creek exists a substantial cattail outcropping/wetlands area. Spring Creek traverses across the southeastern corner of the Quail Hollow Subdivision as it flows in a northeasterly direction. II. DRAINAGE BASINS AND SUB -BASINS A. Major Basin Description No major drainageway exists in the fifth filing of the Quail Hollow Subdivision. The Quail Hollow Subdivision does drain into Spring Creek per the Spring Creek Major Drainageway Plan by Gingery Associates, Inc. dated August 1980. The City of Fort Collins is planning a regional detention pond on the southwest corner of Drake Road and Taft Hill Road in the near future. 1 B. Sub -Basin Description Historic drainage patterns on the subject site are southeasterly across the site to Spring Creek. Several off -site basins lying west of Overland Trail contribute storm water runoff which crosses the Quail Hollow Subdivision. For this report, off -site drainage waters passing through Filings No. 3 and 4 of Quail Hollow, also pass through filing 5 as the storm water runoff is routed to Spring Creek. All off -site flows are currently at historic conditions. Refer to the referenced reports 2-5 for a comprehensive analysis of the off -site basins. III. DRAINAGE DESIGN CRITERIA A. Regulations No deviation from the City of Fort Collins Storm Drainage Design Criteria is sought for the subject site. B. Development Criteria Reference and Constraints Several drainage reports were previously completed for the subject site and adjacent lands as referenced in this report. The Preliminary Drainage Report for Quail Hollow Filings No. 4 through 7 developed the design criteria for the subject site. With the development of Filing No. 5 of Quail Hollow, two temporary detention ponds are planned for construction. The City of Fort Collins is planning a regional detention pond on the southeast corner of Drake Road and Taft Hill Road in the near future. Until the regional detention pond is constructed, the City of Fort Collins has requested that temporary detention ponds be constructed within the upstream developments in order to protect the downstream property owners. The City of Fort Collins has requested that the temporary on -site detention ponds have adequate outlets and detention to reduce developed on -site flows and historic off -site flows to historic conditions as drainage waters leave the site and enter Spring Creek. Per the City of Fort Collins Storm Drainage Criteria, the temporary detention facilities should be designed with outlets sized for the 10 year and 100 year storm events. Also the temporary detention ponds should include an emergency overflow weir/spillway in the event the outlet works become inoperable. Spring Creek lies within the City of Fort Collins Parks property and the outlet pipes from the two detention ponds cross the park property. Per a letter dated 2 November 16, 1989 from the City of Fort Collins Planning Department to Mr. Eldon Ward of Cityscape, in regards to the preliminary review comments on Filings No. 4 through 7, item 4 states "Nuisance flows across the park must be piped". Because 85% of the storms in the Fort Collins area are on the order of a 2 year storm event, the 10 year and under storm event has been assumed as a nuisance flow for this report. C. Hydrological Criteria The rational method was used to determine runoff peak flows from the site and the surrounding off -site tributary areas. The 2,10, and 100 year rainfall criteria, which was obtained from the City of Fort Collins, is the criteria which was utilized. This criteria is included in Appendix A. The detention volumes and release rates were calculated utilizing the Preliminary Drainage Report for Quail Hollow Filings No. 4 through 7 and the Preliminary Drainage Report for the Burns Ranch at Quail Ridge and the calculations are included in Appendix A. The basin boundaries for basins A-1,A-2,A-3,B-1,B-2,B-3,C,D,E,F, and F-1 as utilized in the detention calculations, are not shown on the Filing No. 5 drainage drawing. Rather these basins should be referenced from these subject reports. A reduced copy of the referenced reports drainage drawings are included in Appendix B for reference only. The Filing No. 5 drainage drawing uses basins 1-7 which contain portions of the above described basins. These basins were prepared in this manner for the following two reasons: 1. The overall basins A-1, A-2, A-3, B-1, B-2, B-3, C, D, E, F, and F-1 are utilized in the design of the temporary detention ponds no. 1 and 2. 2. The filing 5 basins 1-7 are used for sizing on -site storm sewer systems, temporary swales, and examining street capacities. Therefore to avoid confusion with all of the basin boundaries, the Preliminary Drainage Report for Quail Hollow Filings No. 4 through 7 and the Preliminary Drainage Report for the Burns Ranch at Quail Ridge should be referenced for those basins not shown on the filing 5 drainage drawing. Included in the back pocket of this report is the Filing No. 5 drainage plan. With the overall basins A-1, A-2, A-3, B-1, B-2, B-3, C, D, E, F, and F-1 contributing flows to the two on -site 3 temporary detention ponds, the best method for sizing the ponds was the Mass Diagram Detention Pond Sizing Method. This method produced the best approximation of the actual detention pond volumes required for the site utilizing the rational method data. D. Hydraulic Criteria All calculations within this study have been prepared in accordance with the City of Fort Collins Drainage Criteria. E. variances from Criteria No variances are being sought for the subject site. IV. DRAINAGE FACILITY DESIGN A. General Concept As development occurs within Quail Hollow Filing No. 5, all on -site fully developed flows will flow southeasterly into one of the two temporary detention ponds. Off -site runoff will be directed through the various filings of the Quail Hollow Subdivision and carried in some manner to the temporary detention ponds. Included in the back pocket of this report is the Filing No. 5 drainage plan. B. Specific Details During the course of preparing the proposed drainage plan for filing 5 of Quail Hollow, various drainage problems arose. Groundwater in the subject site is relatively close to the ground surface per the report titled "Report of a Geotechnical Investigation for Quail Hollow P.U.D. Fourth, Fifth, Sixth & Seventh Filings by Empire Laboratories, Inc.. As a result of a high groundwater table, the site was graded in such a manner to place the foundations of the homes above the ground water table. With the FHA grading requirements and the existing lots of Filing No. 4 of Quail Hollow, the resulting street grades were established. With the existing grades in Filing No. 4 and the FHA grading requirements, the bottom of temporary detention pond no. 2 was established as a result of the availability of the storm sewer system to drain into it. Given the elevation of Spring Creek and temporary detention pond no. 2, a flat bottom is proposed for this pond. Temporary detention pond no. 2 is only to be used until the regional detention pond at Drake Road and Taft Hill Road is completed in the next few years. It is felt that a flat bottom within this pond will work for the short 4 time frame the pond is expected to be in service. Additionally, the location of temporary detention pond no. 2 does not allow for the 100 year volume to be achieved. Therefore, additional volume has been obtained in temporary detention pond no. 1 and the release rates adjusted accordingly. With the site constraints of grading and the existing elevations of Spring Creek, limited fall is available between temporary detention pond no. 2 and Spring Creek. Temporary detention pond no. 2 has been sized with an outfall pipe to carry the 10 year and a portion of the 100 year storm water directly to Spring Creek. The remainder of the 100 year storm water has been routed through an overflow weir and allowed to sheet flow to Spring Creek across the City of Fort Collins Parks property. Within temporary detention pond no. 1 there is an existing wetlands/wildlife area. This area has been created in the natural tributary to Spring Creek over the years. The Quail Hollow development will discharge storm water runoff into the existing wetlands/wildlife area. Storm water runoff will pass through the wetlands/wildlife area and eventually be transported to Spring Creek. It is the intent of this Filing No. 5 development to keep the existing wetland/wildlife area as natural as possible in order to not affect the wetlands area. The proposed detention pond will not drain the existing wetland/wildlife area, but it will allow runoff from the Quail Hollow Subdivision to pass through the wetland/wildlife area and be temporarily stored within this area. The Quail Hollow Subdivision is expected to create minor urban storm water runoff which will pass through the existing wetland/wildlife area with little to no impact upon the area. No drainage construction is anticipated directly within the existing cattail outcroppings of the wetlands area. With the unavailability of area and the site grading constraints of temporary detention pond no. 2, temporary detention pond no. 1 was increased in size to fulfill the site requirements. Calculations for the detention ponds can be found within Appendix A. With the site constraints of grading and the existing elevations of Spring Creek, limited fall is available between temporary detention pond no. 1 and Spring Creek. Temporary detention pond no. 1 has been sized with an outfall pipe to carry the 10 year and a portion of the 100 year storm water directly to Spring Creek. The remainder of the 100 year storm has been routed through an overflow weir and allowed to sheet flow to Spring Creek across the City of 5 Fort Collins Parks property. Adequate detention has been provided within temporary detention ponds no. 1 and 2 for Quail Hollow Filings No. 4 through 7 and also the Burns Ranch at Quail Ridge proposed development west of Overland Trail. In the event that the outlets of either temporary detention pond become inoperable, emergency overflow weirs/spillways have been designed to safely pass storm water flows, in a sheet flow manner, to Spring Creek. The downstream side of the overflow weir/spillways should contain a riprap lining in order to preserve the pond embankments. Adequate freeboard of 1 foot has been provided above the normal 100 year storm water surface level to safely operate the emergency overflow weir/spillways without breaching the entire downstream embankment of each pond. Within basins 5 and 6 of Filing No. 5, a storm sewer system has been provided to transport the 2 year storm water runoff into temporary detention pond no. 2. The 100 year storm water runoff from basins 5 and 6 is proposed to be transported into temporary detention pond no. 2 by the streets and a grass swale between two lots at the end of Lame Beaver Court. Adequate freeboard is provided above the 100 year water surface level in the swale to safely pass the 100 year storm water between the two lots and into temporary detention pond no. 2. Basin 1 drains onto Blue Leaf Drive. Blue Leaf Drive will eventually connect into Overland Trail with additional filings of Quail Hollow. For the interim, Blue Leaf Drive dead ends at the end of Filing No. 5. A temporary swale has been sized to safely convey the 2 and 100 year storm water runoff from Blue Leaf Drive into temporary detention pond no. 1. Adequate freeboard is provided above the 100 year water surface level to ensure that the storm water runoff reaches temporary detention pond no. 1. Basins 3 and 4 drain onto Dixon Creek Lane. Dixon Creek Lane will eventually end at a cul-de-sac with additional filings of Quail Hollow. For the interim, Dixon Creek Lane dead ends at the end of Filing No. 5. A temporary swale has been sized to safely convey the 2 and 100 year storm water runoff from Dixon Creek Lane into temporary detention pond no. 1. These flows will ultimately be transported into temporary detention pond no. 2 with the completion of Dixon Creek Lane. For the interim, temporary detention pond no. 1 is closer and the total buildout`contributing storm water runoff into temporary detention pond no. 1 has not occurred, therefore the R V. runoff has been directed into this pond. Adequate freeboard is provided above the 100 year water surface level to ensure that the storm water runoff reaches temporary detention pond no. 1. Off -site basin 0-1 in Filing No. 4 of Quail Hollow has been draining into a temporary detention pond near the intersection of Michener Drive and Mercy Drive. With the development of Filing No. 5 of Quail Hollow, this detention pond will be removed. Therefore a temporary swale has been sized to safely convey the 2 and 100 year storm water runoff from Michener Drive into temporary detention pond no. 2. Adequate freeboard is provided above the 100 year water surface level to ensure that the storm water runoff reaches temporary detention pond no. 2. The temporary detention pond for Quail Hollow Filing No. 4, currently located between Blue Leaf Drive and Dixon Creek Lane immediately south of Yorkshire Street, will be removed with the development of Filing No. 5. All previous flows into the Filing No. 4 pond will be conveyed to temporary detention pond no. 1 in Tract A of Filing No. 5. A swale between the lots off of Dixon Creek Lane and Blue Leaf Drive has been sized to safely convey the 2 and 100 year storm water runoff from the existing 48" RCP at Yorkshire Street to temporary detention pond no. 1. Adequate freeboard is provided above the 100 year water surface level to ensure that the storm water runoff reaches temporary detention pond no. 1. EROSION CONTROL A. General Concept It is our understanding that the new City of Fort Collins Erosion Control Reference Manual will become effective with the May 1991 submittals. Therefore for this submittal, only a general overview of erosion control will be addressed. Future filings of Quail Hollow will need to have the erosion control calculations completed and conform to the Erosion Control Reference Manual. B. Specific Details For Filing No. 5 of Quail Hollow, the overlot grading results in portions of the site ending some 2-4 feet above the surrounding ground. Thus behind some of the lots the proposed ground will slope down to the existing ground at a 4:1 slope. The potential for erosion and sediment transport off -site is high in these areas. Therefore, sediment collection straw bales should be 7 placed at the toe of the fill slopes in these areas. The temporary swales from Basins 1,3,4, and 0-1 to the temporary detention ponds will be cut through native soil. The potential for erosion to occur in these swales and transport sediment into the temporary detention ponds is high. Therefore, erosion straw bale check dams should be placed along the swales to control the erosion and transport of sediment into the temporary detention ponds. The storm sewer system in Mercy Drive and Lame Beaver Court results in the construction of a 10 foot type R curb inlet and a 5 foot type R inlet. With the overlot grading on the adjacent lots and the subsequent housing development, erosion control curb inlet gravel filters should be placed around the inlets to prohibit sediment transport into temporary detention pond no. 2. All disturbed ground should be reseeded as soon as the grading has been completed in order to limit wind and rain erosion and the resultant sediment transportation. VI. 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 adequately provide the detention of developed on -site flows from the Quail Hollow Subdivision Filings 4 through 7 and the proposed Burns Ranch at Quail Ridge Subdivision. By creating temporary detention ponds no. 1 and 2, all developed storm water runoff has been controlled in order to eliminate off -site downstream damage from the 10 year and 100 year storm events. The 10 year and 100 year release structures in temporary detention ponds no. 1 and 2 release flows at historic levels. The proposed storm sewer system will adequately transport the 2 year storm water runoff from Mercy Drive and Lame Beaver Court into temporary detention pond no. 2. The proposed street system will adequately transport the 2 year storm water runoff to the proposed storm sewer system. The proposed street system will adequately transport the 100 year storm water runoff to the proposed swale between the two lots at the end of Lame Beaver Court. 8 The proposed temporary swales into temporary detention ponds no. 1 and 2 will adequately transport the 2 year and 100 year storm water runoff to the proposed ponds. The a ropoand d o o street year storm waters runoff ly transport the 2 y f fto the proposed temporary swales. The proposed drainage concepts presented in this report and shown on the drainage plan are in compliance with the City of Fort Collins criteria. REFERENCES 1. Storm DrainagefForteCollins1teria and Colorado Mays1984tion Standards by the City 2. Quail He 1 ow Report Subdivision, by RBD, Filings Inc . , Eng inee ring Consultants, Drainage P November 1989. 3. Final Drainage Report for Quail Hollow P.U.D., Third Filing by RBD Inc., Engineering Consultants, May 1988. 4, Quail Hollow Subdivision, Filing 4 Final Drainage Report by RBD, Inc., Engineering Consultants, March 1990. 5, Preliminary Drainage Report for the Burns Ranch at Quail Ridge by RBD, Inc., Engineering Consultants, December 21, 1990. 6. Report of a Geotechnical Investigation for Quail Hollow P.U.D. Fourth, Fifth, Sixth & Seventh Filings by Empire Laboratories, Inc., November 3, 1989. 7. Spring Creek Major Drainageway Plan for the City of Fort Collins, Larimer County Colorado by Gingery Associates, Inc., August 1980. i 9 11 APPENDIX A 711 X 365.? A .... .... ... U.J r:: +Y,,\ �` 1./' is if l� L ,,j l ' 1 f ' ' 1 _ &I; . . . . ......... P it 5 T 1505q Stu-- .y . 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