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Home My WebLink AboutREGISTRY RIDGE, 4TH FILING - FDP - 32-95H - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTDrainage Design Considerations Registry Ridge P.U.D., Fourth Filing December 5, 2001 REFERENCES Northern Engineering Services, Inc 1) Final Drainage Report for Registry Ridge P.U.D. First Filiniz, Fort Collins, Colorado, Northern Engineering Services, Inc., May 19, 1997. 2) Final Drainage Report for Regisgy Ridge P.U.D. Third Filing, Fort Collins, Colorado, Northern Engineering Services, Inc., August 23, 2000. 3) Fossil Creek Drainage Basin Master Drainageway Planning Study, City Of Fort Collins, Simons, Li & Associates, Inc., August 1982. 4) Storm Drainage Design Criteria and Construction Standards, City of Fort Collins, Colorado, May, 1984. 5) Drainage Criteria Manual, Urban Drainage and Flood Control District, Wright - McLaughlin Engineers, Denver, Colorado, March, 1969. Drainage Design Considerations Registry Ridge P.U.D., Fourth Filing December 5, 2001 Northern Engineering Services, Inc 6.2 Rainfall Erosion Control Plan The proposed rainfall erosion control plan during construction will consist of temporary structural erosion control measures. Gravel inlet filters will be placed at all curb inlets. A sediment trap will be placed at the outlet of existing Pond 603. Silt fencing will be installed at the locations specified on the Drainage and Erosion Control plan to prevent the migration of sediment. All procedures listed under the City of Fort Collins Standard General Grading and Erosion Control Notes shall be strictly followed. It has been clearly noted on the Grading Plan that no soils shall remain exposed for more than thirty days before requiring temporary or permanent erosion control measures, unless approved by Stormwater Utility. Computation of the "Performance Standard" and "Effectiveness" of the Erosion and Sediment Control Plan are presented in Appendix I of this report. The proposed erosion control plan after construction will consist of permanent riprap, which will be provided at the locations specified on the construction plans. All open space areas and grass -lined swales will be seeded with a permanent dry -land seed mix as specified on the Landscape Plan. An erosion control cost estimate for "during construction" sediment control has been provided for the Fourth Filing (See Appendix 1). VII. CONCLUSIONS 7.1 Compliance with Standards All drainage design considerations are in accordance with the City of Fort Collins Storm Drainage Design Criteria Manual (SDDCM), the Urban Drainage and Flood Control District's Drainage Criteria Manual, and the Final Drainage Report for Registry Ridge P.U.D., First Filing. Drainage Design Considerations Registry Ridge P.U.D., Fourth Filing December 5, 2001 Northern Engineering Services, Inc 4.7 SWMM Modeling There will be no SWMM modeling performed as part of this Fourth Filing drainage study. All SWMM modeling has been completed and approved by the City of Fort Collins as part of the Registry Ridge First Filing submittal. The approved SWMM model has included a site plan with an impervious area greater than that currently being proposed with the Fourth Filing submittal. 4.8 HEC-2 Modeling There will be no HEC-2 model performed as part of this Fourth Filing drainage study. All HEC-2 modeling has been completed as part of the First Filing submittal and is contained in the report entitled Final Drainage Report for Registry Ridge P.U.D. First Filing, Volume 2, Section I. 4.9 Off -site Improvements A small amount of off -site grading will be required to accommodate a proposed pedestrian pathway. A proposed 12'x 4' reinforced concrete box culvert will cross existing Swale 603, connecting the pathway between Registry Ridge Third and Fourth Filings. Details of the culvert and re -grading can be found on the Fourth Filing construction drawings. Also, we are proposing that the existing outlet structure for Pond 603 be modified to provide a water quality capture volume. V. WATER QUALITY 5.1 Water Quality Measures and Criteria While Detention Pond 603 was designed with Registry Ridge First Filing to provide detention storage for the Fourth Filing site, it was not designed with a water quality capture volume (WQCV). We are proposing that Pond 603 be utilized to provide water quality, not only for the Fourth Filing site, but for the entire Basin 403 that drains into the pond. Based on criteria for a 40-hour dry extended detention basin outlined in the Urban Storm Drainage Criteria Manual Volume 3 — Best Management Practices by the Urban Drainage and Flood Control District (September 1999), we determined the required water quality capture volume to be 1.878 acre-feet. The existing outlet structure of Pond 603 will be modified to provide this WQCV. According to the "As -Constructed" stage -storage table for Pond 603, the required WQCV is achieved at an elevation of 5050.089. The 100-year water surface elevation of Pond 603 was recalculated with the as -constructed pond volume and the water quality modified outlet structure. The 100-year water surface elevation for Pond 603 will now be at 5052.34 instead of 5052.21. Freeboard exists up to an elevation of 5053.30, so the existing pond has adequate volume for both detention storage, and water quality capture volume. VI. EROSION CONTROL PLAN 6.1 Erosion Control Criteria The erosion control plan presented here is intended to control both wind and rainfall erosion. The Erosion Control Reference Manual for Construction Sites (ECRM), City of Fort Collins, has been referenced for this erosion control plan. 5 Drainage Design Considerations Northern Engineering Services, Inc Registry Ridge P.U.D., Fourth Filing December 5, 2001 Inlet B 1 into Detention Pond 603. Basin 4a consists of the rear portions of the units located on the north side of Cabot Court. This basin drains to Swale B-B, and travels through four (4) typical sidewalk culverts labeled Culvert B. Swale B-B drains into existing Swale 603. Runoff from Basin 4b will travel into the vertical curb and gutter of Cabot Court, and be conveyed to a 4' sidewalk culvert located at the low point of Cabot Court. The 4' sidewalk culvert drains into existing Swale 603, which carries flow into Pond 603. Basin 5 consists of landscaped area and the rear portion of some duplex units. Runoff from this basin will be collected in proposed Swale Section A -A, and travel into Pond 603. Basins 6 and 7 are comprised of landscaped area and the rear portion of some duplex units. Stormwater from these two basins will travel overland directly into Swale 603 and Pond 603. Developed runoff from basin 8 will travel into the vertical curb and gutter in Bon Homme Richard Drive, and head west into existing sump Inlet 30 (15' Type R). Inlet 30 was designed with Registry Ridge First Filing to carry 21.56 cfs. The inlet will now intercept 22.96 cfs with no necessary changes. Stormwater from basin 9 will travel into the vertical curb and gutter in Bon Homme Richard Drive, and head east into existing sump Inlet 33 (10' Type R). Inlet 33 was designed with Registry Ridge First Filing to handle 4.8 cfs. Inlet 33 will now have 6.5 cfs draining into it with no required changes. Runoff from basin 10 will travel into the vertical curb and gutter in Shields Street, and head south to existing Inlet 17 (15' Type R). Inlet 17 is an on - grade inlet designed with First Filing to intercept a 2-year flow of 2.2 cfs. The 2-year runoff to Inlet 17 will be approximately 1.3 cfs, so the existing inlet is adequate. 4.6 Detention Since the assumed runoff from Fourth Filing was greater in the Registry Ridge First Filing report than what is actually being proposed, the original runoff hydrograph from Basin 403 has been used to analyze Detention Pond 603. A stage -storage table was computed from as - constructed survey data of Pond 603 provided by the Sear Brown Group. A user -defined stage - discharge table was then created accounting for the modifications to the existing outlet structure. Discharges at elevations below the water quality capture volume elevation of 5050.089 were set to 0.0 cfs. A reservoir was created in Eagle Point using the as -constructed stage -storage volume of Pond 603 along with the water quality modified stage -discharge table for Culvert 603. The stormwater hydrograph computed from the SWMM file PDl00FC.DAT as defined in the Final DrainageReport for Registry Ridge P.U.D. First Filing, Volume 1, Section A was then routed through the pond to create an accurate stage -storage -discharge table for Detention Pond 603. The analysis resulted in a 100-year water surface elevation of 5052.34 with a corresponding 100- year release rate of 69.2 cfs. This discharge is slightly higher than the original 67.8 cfs design discharge, and the 100-year water surface elevation has been raised from the design elevation of 5051.93 to 5052.34. However, according to the drainage certification letter submitted by Northern Engineering Services, Inc. on February 12, 2001, the design storage volume of Pond 603 was not actually reached until 5052.21 as opposed to the design elevation of 5051.93. A water surface elevation of 5052.21 results in a discharge of approximately 71.6 cfs according to the stage discharge table for Pond 603 in the First Filing report. In reality, the proposed modifications will decrease the actual release rate by a nominal amount. There is still approximately one -foot of freeboard in the pond up to an elevation of 5053.30. The emergency overflow structure will remain in place, and will not be adversely affected by the proposed modifications. 4 Drainage Design Considerations Registry Ridge P.U.D., Fourth Filing December 5, 2001 Northern Engineering Services, Inc 4.4 Hydraulic Criteria The City of Fort Collins Storm Drainage Design Criteria has been referenced for all hydraulic calculations. In addition, the following computer programs have been utilized: • The computer program "UDINLET" has been used to analyze inlet capacities, • The computer program "FlowMaster" has been used to analyze the swales and street capacities, • The computer programs "CulvertMaster" and HY-8 have been used to analyze the culverts, • The computer program "Storm Sewer Modeling" has been used to analyze the capacity of the proposed storm sewers, • The computer program "Watershed Modeling" has been used to route the SWMM hydrograph through the modified detention pond, • The computer program "Riprap" has been used to size the proposed riprap The hydraulic analysis of Lang Gulch was evaluated as part of the First Filing through the use of the HEC-2 computer model. Input and output files of all HEC-2 runs are included in the Final Drainage Report for Registry Ridge P.U.D. First Filing, Volume 3, Section I. 4.5 Drainage Patterns The entire Fourth Filing site will drain into existing Detention Pond 603. This pond was designed with Registry Ridge First Filing. The site was assumed to be 59% impervious, and a custom rainfall intensity was used. The peak 100-year runoff from the site using 59% imperviousness along with the rainfall intensities defined in the Final Drainage Report for Registry Ridge P.U.D., First Filing is approximately 39.5 cfs. The peak I00-year runoff from Fourth Filing using the proposed site plan (48% impervious) along with the rainfall intensities re- defined by the City of Fort Collins in 1999 is approximately 33.8 cfs. Therefore, the runoff from Fourth Filing to existing Detention Pond 603 is less than what was assumed when the pond was designed. The Registry Ridge development is divided into five (5) major drainage Basins 401-405 (See Final Drainage Report for Registry Ridge P.U.D. First Filing). The Fourth Filing is contained entirely in Basin 403. The Fourth Filling site has been sub -divided into 10 Basins labeled 1-10. Basin 1 has further been divided into sub -basins 1 a, I b, and I c. Developed stormwater from Basin la will be conveyed overland into rollover curb and gutter located on the southern edge of the private drive. From there, water will travel to the west via the curb and gutter, through a 2' wide v-pan with 6" vertical sides, and into Nimitz Drive. Stormwater from Basin lb will travel overland into rollover curb and gutter located on the south side of the private drive. From there, flow will be conveyed via the curb and gutter to the east, through a 2' wide v- pan with 6" vertical sides, and into Enterprise Drive. Developed runoff from Basin I c will travel overland directly into the vertical curb and gutter of Hornet Drive. All runoff from Basin 1 (a-c) will travel to a 10' Type R Curb Inlet (A3) at the low point of Hornet Drive. Runoff from Basin 2 will also travel overland into curb and gutter, and then be conveyed to a proposed 10' Type R Curb Inlet (A2) at the low point of Hornet Drive. Storm Sewer Line A will collect runoff from both inlets and carry the water into Detention Pond 603. Developed stormwater from Basin 3 will travel overland into vertical curb and gutter, and be conveyed to proposed 5' Type R Curb Inlet (B 1) at the low point of Kitty Hawk Court. Storm Sewer Line B will carry the water from Drainage Design Considerations Registry Ridge P.U.D., Fourth Filing December 5, 2001 Northern Engineering Services, Inc III. PREDEVELOPMENT CONDITIONS 3.1 Maior Basin Description The site is located in the Fossil Creek Drainage Basin and is included in the report entitled Fossil Creek Drainage Basin Master Drainageway Planning Study, by Simons, Li & Associates, Inc., August, 1982. The. SWMM model developed as part of this Master Study has been updated by Northern Engineering as part of the First Filing Final Drainage Report to reflect proposed developed conditions for the entire Registry Ridge site, which includes the Fourth Filing. 3.2 Predevelopment Drainage Patterns The Fourth Filing site historically drains from the north to the south at slopes ranging from 2% to 10% into Detention Pond 603. While the Fourth Filing site is currently undeveloped, it was accounted for in the overall drainage master plan for the entire Registry Ridge site submitted with Registry Ridge First Filing. IV. POSTDEVELOPMENT CONDITIONS 4.1 Post-devel_pment Conditions The Fourth Filing development will include the following: • residential duplex units; • new local streets; • utility improvements Some off -site grading will be required into Registry Ridge Third Filing to accommodate a pedestrian pathway and a proposed box culvert. 4.2 Design Criteria and References Drainage criteria outlined in both the City of Fort Collins Storm Drainage Design Criteria Manual. (SDDCM) and Storm Drainage Criteria Manual by the Urban Drainage and Flood Control District have been referenced for this study. 4.3 Hydrologic Criteria The Rational Method has been used to estimate peak stormwater runoff within the developed site. The initial 2-year and major 100-year design storms have been used in the design of the proposed drainage system, which include storm inlets, culverts, storm sewer and swales. Rainfall intensity data for the Rational Method has been taken from Figure 3-1a updated by the City of Fort Collins in 1999. These rainfall intensities were used for the design of all new improvements being proposed with the development of Fourth Filing. In addition, the original hydrology performed with Registry Ridge First Filing was re-evaluated with the new site imperviousness and new rainfall criteria to ensure that Detention Pond 603 was adequately sized. SWMM modeling has also been performed as part of an overall hydrologic analysis of the Registry Ridge development. The Final Drainage Report for Re ig_sgy Ridge First Filing, Volume 1, Section A, contains all input and output files and supporting calculations pertaining to this analysis. The SWMM model has accounted for the Fourth Filing being fully developed in the file PD100FC.DAT. Drainage Design Considerations Registry Ridge P.U.D., Fourth Filing December 5, 2001 Northern Engineering Services, Inc Drainage Design Considerations for Registry Ridge P.U.D., Fourth Filing Fort Collins, Colorado December 5, 2001 I. INTRODUCTION 1.1 Objective This report summarizes the results of a comprehensive analysis of both pre- and post - development hydrologic and hydraulic conditions, for the Registry Ridge Fourth Filing development. 1.2 Mapping and Surveying Aerial topography of the site was provided by JR Engineering with a contour interval of one (1) foot. In addition, a site survey was done in September of 2000 by the Sear -Brown Group after the construction of Bon Homme Richard Drive to obtain the most current topography for the site. 1.3 Site Reconnaissance A site visit was conducted on June 28, 1996 by the project engineer. Based on the topographic mapping, existing drainage basins and land use were confirmed as well as existing structures. The location and dimensions of existing culverts were verified as well as their condition and flow direction. An additional site visit was conducted on August 24, 2000 to verify that no changes had been made to the area since the previous visit. It was determined that the topography along Bon Homme Richard Drive and Shields Street may be different than what the original topography shows. The additional survey by the Sear -Brown Group verified that the topography had changed, and the updated contours were used as the basis of our design. II. SITE LOCATION AND DESCRIPTION 2.1 Site Location The site is located within the East Half of Section 15, Township 6 North, Range 69 West of the 6th Principal Meridian in Fort Collins, Colorado. The project is bounded by Bon Homme Richard Drive on the north, Shields Street on the east, existing swale 603 on the west, and existing detention Pond 603 on the south (See Vicinity Map). 2.2 Site Description Registry Ridge P.U.D. Fourth Filing ("Fourth Filing") is approximately 8.15 acres and has historically been furrowed agricultural land. There are no existing structures located on the site. The only existing utilities are a sanitary sewer line that runs along the southern property boundary and a storm sewer line that runs along the eastern property boundary. These improvements are part of Registry Ridge First and Third Filings. The Fourth Filing is located south of Registry Ridge Second Filing, which is currently beginning construction. DECEMBER, 2001 �T VICINITY MAP l� 1 "=2000' Table of Contents VICINITY MAP I. INTRODUCTION 1.1 Objective...................................................................................... 1.2 Mapping and Surveying................................................................ 1.3 Site Reconnaissance...................................................................... II. SITE LOCATION AND DESCRIPTION 2.1 Site Location................................................................................ 2.2 Site Description............................................................................ III. PRE -DEVELOPMENT CONDITIONS 3.1 Major Basin Description................................................................ 3.2 Pre -development Drainage Patterns ................................................ IV. POST -DEVELOPMENT CONDITIONS 4.1 Post -development Conditions......................................................... 4.2 Design Criteria and References...................................................... 4.3 Hydrologic Criteria........................................................................ 4.4 Hydraulic Criteria.......................................................................... 4.5 Drainage Patterns......................................................................... 4.6 Detention........................................................................................ 4.7 SWMM Modeling......................................................................... 4.8 HEC-2 Modeling........................................................................... 4.9 Off -site Improvements................................................................... V. WATER QUALITY 5.1 Water Quality Measures and Criteria ............................................. VI. EROSION CONTROL PLAN 6.1 Erosion Control Plan and Criteria .................................................. 6.2 Rainfall Erosion Control Plan ........................................................ VII. CONCLUSIONS 7.1 Compliance with Standards........................................................... REFERENCES....................................................................................... APPENDICES APPENDIX A - APPENDIX B - APPENDIX C - APPENDIX D- APPENDIX E - APPENDIX F - APPENDIX G - APPENDIX H- APPENDIX I - APPENDIX J - APPENDIX K - Hydrology Design of Inlets Design of Storm Sewers Design of Swales Design of Culverts Riprap Calculations Street Capacity Calculations Water Quality Erosion Control Calculations Detention Pond Calculations Review Comments & Responses Page 2 2 2 2 2 3 3 4 5 5 5 G J 5 6 6 7 N 0 R I H I R N E N G I N E E R I N G December 5, 2001 City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, Colorado 80521 RE: Registry Ridge P.U.D., Fourth Filing Fort Collins, Colorado Project Number: 00-040.06 Dear Staff - Northern Engineering Services, Inc,, is pleased to submit this revised Final Drainage Report for Registry Ridge P.U.D., Fourth Filing for your review. We understand that review by the City of Fort Collins is to assure general compliance with standardized criteria contained in the Storm Drainage Design Criteria and Construction Standards. This report was prepared in compliance with technical criteria set forth in the City of Fort Collins Storm Drainage Design Criteria and Construction Standards manual. If you should have any questions or comments as you review this report, please feel free to contact us at your convenience. Sincerely, NORTHERN ENGINEERING SERVICES, INC. /U Nicholas W. Haws, E.I.T. Project Engineer Roger A. C#rtiss, P.E. = o 27362 Project Manager/Vice President l e 420 SOUTH HOWES, SUITE 202, FORT (OLLINS, (OLORADO 80521, (970) 221-4158, FAX (970) 221-4159 Drainage Design Considerations for Registry Ridge P.U.D., Fourth Filing Fort Collins, Colorado December 5, 2001 Prepared For: U.S. Home Corporation Colorado Division 6000 S. Greenwood Plaza Blvd., Suite 200 Englewood, Colorado 80111 Prepared By: NORTHERN ENGINEERING Northern Engineering Services, Inc 420 S. Howes, Suite 202 Fort Collins, Colorado 80521 Phone: (970) 221-4158 Project Number: RFF 00-040.06 Final Compliance