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Home My WebLink AboutREGISTRY RIDGE PUD, 3RD FILING - FINAL - 32-95E - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTFinal Drainage Report Registry Ridge P.U.D. Third Filing l,dv 15, 1997 Northern Engineering Services, Inc. TABLE OF CONTENTS PAGE Section A: Al- A17 On -Site Hydrology......................................................... Section B: B1- B1 Street Capacity................................................................. Section C: C1- C1 Designof Inlets..................................................................... Section D: D1- DS Designof Swales..................................................................... Section E: El- E33 Design of Culverts..................................................................... Section F: F1- F_ Design of Storm Sewers............................................................ Section G: G1- G1_ Riprap Calculations..................................................................... Section H: Erosion Control Calculations .................................... • • • • • • - • • H 1- H Page 7 Final Drainage Report Registry Ridge RUD. Third Filing July 14. 1997 Northern Engineering Services. Inc. REFERENCES 1). Final Drainage Resort for Registry Ridee P.U.D. First Filing, Fort Collins, Colorado, Northern Engineering Services, Inc., May 19, 1997. 2.) Fossil Creek Drainage Basin Master Drainaeewav Planning Studv, City Of Fort Collins, Simons, Li & Associates, Inc., August 1982. 3.) Storm Drainage Design Criteria and Construction Standards, City of Fort Collins, Colorado, May, 1984. 4.) Drainage Criteria Manual, Urban Drainage and Flood Control District, Wright - McLaughlin Engineers, Denver, Colorado, March, 1969. Page 6 Final Drainage Report Northern Engineering Semces. Inc. Registry Ridge P-U.D. Third Filing ., lulu 15. 1997 V. EROSION CONTROL 5.1 Erosion Control Plan Permanent riprap will be provided at the outlet of all culverts and storm sewers. Grass - lined swales and detention ponds shall be seeded immediately upon completion with the permanent seed mix specified on the Grading Plan. Temporary sediment control consisting of straw bale dikes will be used in swales until permanent vegetation is established. Gravel filters will be required at all curb inlets and silt fencing installed adjacent to ponds and drainageways. See the Grading Plan for additional information. 3 An erosion control cost estimate has been provided for the Third Filing (See Section I H). r I VI. CONCLUSIONS 6.1 Compliance with Standards All drainage analyses have been performed according to the City of Fort Collins Storm Drainage Design Criteria Manual (SDDCM) and the Urban Drainage and Flood Control District's Drainage Criteria Manual. No variances are requested as part of the proposed Third Filing development. Page 5 Final Drainage Repon Northern Engineering Services. Inc. Registry Ridge PI'.D. Third Filing w Juhv I5. 1995 4.5 Drainage Concept Detention is not a requirement within the Fossil Creek Major Drainage Basin. The developer (Colorado Land Source LTD., "Developer") of Registry Ridge however, desires to incorporate both on and off -site detention facilities into the drainage system to provide a water quality mechanism as well as negate the possibility of further bank erosion along Lang Gulch and Smith Creek. Also, according to the Master Plan, development would not be allowed in the floodplain. The Registry Ridge site is divided into five (5) major drainage basins 401-405 (See Developed Overall Drainage Plan 2/4). The Third Filing will include a portion of Basin 403 and, Basins 404 and 405 in their entirety. Developed stormwater will be conveyed overland and through the streets to proposed on -site stormwater sewers and swales and then conveyed to either Pond 603 (part of the First Filing) or directly to Lang Gulch undetained. p Developed stormwater runoff from Basin 403 is routed to proposed Pond 603 for I detention. Pond 603 has been designed as part of the First Filing. Runoff from Basin 404 is routed to Lang Gulch via Swales 47- 49. Developed stormwater from this basin will be undetained. Runoff from Basin 405 flows overland to Lang Gulch. Developed stormwater from this basin will be undetained. Basins 405H (1.546 acres) and 405K (0.365 acres) will flow onto adjacent off -site properties at rates which will be less than historic (see Section A). 4.6 SWMM Modeling All revisions to the SWMM model will take place when addressing city comments to the First Filing and will be included in the Final Drainage Report for Registry Ridge P.U.D. First Filing, Volume 1, Section A. 4.7 HEC-2 Modeling All revisions to the HEC-2 model will take place when addressing city comments to the First Filing and will be included in the Final Drainage Report for Registry Ridge P.U.D. First Filin , Volume 2, Section I. 4.8 Off -site Improvements No off -site drainage improvements are proposed as part of the Third Filing development. 4.9 Construction Phasing No construction phasing is proposed as part of the Third Filing development. Page 4 u I Final Drainage Report Northern Engineering Services. Inc. Registry Ridge P.U.D. Third Filing Juhv 15, 1997 • culvert crossings. The downstream parcel of land, from the east side of Shield Street to the C&S Railroad tracks, is owned by Colorado Land Source Ltd. which is also the developer of Registry Ridge P.U.D.. All required off -site easements for drainage and grading have been obtained. 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 Final Drainage Study. 4.3 Hydrologic Criteria The Rational Method has been used to estimate peak stormwater runoff within the i developed site. The initial 2-year and major 100-year design storms have been used in the I design of the proposed drainage system which include swales, inlets, storm sewers and culverts. Rainfall intensity data for the Rational Method has been taken from IDF curves and L equations generated specifically for the Registry Ridge P.U.D. site by the computer program l "Watershed Modeling" by Eagle Point. Input of precipitation amounts have been taken from the NOAA Atlas 2, Volume III - Colorado. Compared to Figure 3-1 in the SDDCM, rainfall r intensities generated for the Registry Ridge site were approximately 15% higher than 1 intensities given in Figure 3-1. SWMM modeling has also been performed as part of an overall hydrologic analysis of the Registry Ridge development. The Final Drainage Report for Registry Ridge First Filing, Volume 1, Section A, contains all input and output files and supporting calculations pertaining this analysis. SWMM will be revised when addressing the First Filing city comments and will include the final developed conditions of the Third Filing. 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: s The computer program "HY8" by the U.S. Department of Transportation, Federal Highway Administration has been used to size all culvert crossings and riprap outlet protection at the culverts, • The computer program "UDINLET" has been used to analyze inlet capacities, • The computer program "Flowmaster" has been used to analyze the capacity of proposed swales, The hydraulic analysis of Lang Gulch will be evaluated as part of the First Filing revisions 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. Page 3 Final Drainage Report Registry Ridge P.G.D. Third Filing Julv 15. 1997 Northern Engineering Sen•ices. Inc. 2.3 Irrigation Ditches and Drainageways Lang Gulch traverses the south end of the Third Filing flowing from west to east. The City of Fort Collins ("City") has defined the 100-year floodplain for Lang Gulch which is reflected on the Drainage and Grading Plans. Development of the Third Filing will not encraoch into the Lang Gulch floodplain. There are no existing irrigation laterals on the site. 1 III. HISTORIC DRAINAGE BASIN i 3.1 Major 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 & j Associates, Inc., August, 1982. The SWMM model developed as part of this Master Study f 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. 3.2 Historic Drainage Patterns The Third Filing site historically drains from northwest to southeast at slopes ranging from 2.9 to 10.0% (see Historic Overall Drainage Plan, Sheet 1/4). The entire Third Filing site is tributary to Lang Gulch which drains to the upstream side of the culvert crossing at Shields Street. The existing culvert crossing under Shields Street at Lang Gulch has been field d verified as a sixty (60) inch RCP. Ponding presently occurs along Lang Gulch upstream of South Shields Street, C&S Railroad Crossings 3 & 4 and Trilby Road. Off -site runoff enters the site along the west property line. Approximately 68.651 acres of off -site runoff (Basins 6 and 157) will be routed through the Third Filing to Lang Gulch via SWMM Conveyance Element 800 (see Fossil Creek Basin SWMM Schematic, Sheet 3/4). There are existing wetlands located on -site adjacent to Lang Gulch and have been delineated on the Historic Overall Drainage Plan. A separate report, prepared by Riverside Technology, was included with the Preliminary submittal for Registry Ridge P.U.D.. Existing wetlands will remain undisturbed. ■ IV. DEVELOPED DRAINAGE 4.1 Developed Conditions Planned development within Registry Ridge P.U.D. Third Filing include: • Single Family Residential Homes, e Open Space, 6 new local streets, i Page 2 i Final Drainage Report for Registry Ridge P.U.D. Third Filing Fort Collins, Colorado July 14. 1997 INTRODUCTION 1.1 Objective To provide a final drainage scheme for the proposed Registry Ridge planned unit development Third Filing based on the following criteria. 1. To adopt the drainage concepts contained in the Fossil Creek Drainage Basin Master Drainagewav Planning Study, ("Master Study", Reference 1); 2. To consider the drainage schemes of all adjacent properties and previous filings of Registry Ridge P.U.D.; 3. To consider any possible adverse effects downstream of the development due to developed stormwater. 1.2 Mapping and Surveying Topography of the site was provided to Northern Engineering Services by JR Engineering with a contour interval of one (1) foot. 1.3 Site Reconnaissance A site visit was conducted on June 28, 1996 by the project engineer. Based on the itopographic mapping, existing drainage basins and land use were confirmed as well as existing 1 structures. The location and dimensions of existing culverts were verified as well as their condition and flow direction. 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 Trilby Road on the north and Shields Street on the east. (See Vicinity Map). 2.2 Site Description Registry Ridge P.U.D. Third Filing ("Third Filing") is approximately 80.607 acres and has historically been furrowed agricultural land. There are two existing residences located south and east of the Third Filing site. There are no existing structures on the site. J d w a 0� VICINITY MAP ® SCALE:1-.aMO' w o w !U 'W N9 Ze IW3el I�gal Z_s; w Z� W I� a: p Z i 1 �I 7'1 i E N G I N E E R I N SIERVI(ES INC July 15, 1997 City of Fort Collins Stormwater Utility 235 Mathews Fort Collins, Colorado 80522 RE: Registry Ridge P.U.D. Third Filing Fort -Collins, Colorado Project Number: 9735.00 Dear Staff: Northern Engineering Services, Inc. is pleased to submit this Final Drainage Report for Registry Ridge P.U.D. Third Filing for your review. 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 me at your convenience. Sincerely, NORTHERN YV1_Vn) Mary B. WoI , INC. 1 420 SOUTH HOWES, SUITE 202, FORT COLLINS, COLORADO 80521, (970) 221-4158, FAX (970) 221-4159 Final Drainage Report for Registry Ridge P.U.D. Third Filing Fort Collins, Colorado July 15, 1997 Prepared For: Colorado Land Source, LTD. 9085 East Mineral Circle, Suite 200 Englewood, Colorado 80112 Prepared By: MOLHOWN Norlhem Engineedng Services, Inc 420 S, Howes, Suite 202 Fort Collins, Colorado 80521 Phone: (970)221-4158 Project Number: 9735.00