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Home My WebLink About2337 S. SHIELDS ST., HOME STATE BANK - FDP - 8-05A - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTH yi f ( UI tt1lID�� (1L L ! LEI , ROLLAND MOORE PARK (— ,1 PROJECT LOCATION f _� J T �1 SENIOR -- i I. `, CENTER ' r (, 7 � I I, FF1 7 11, S F ROCKY MOUNTAIN HIGH SCHOOL DATE: 3/01/05 SCALE: 1"=800' DESIGNED BY: SB JOB NO.: 238-01 ' 0 0 ' Lj I� r HOME STATE BANK VICINITY MAP cl SHEET 1 OF 1 I North Star ft- design, inc. 700 Automation Drive, Unit I Windsor, Colorado 80550 Phone: 970-686-6939 Fax: 970-686-1188 APPENDIX A VICINITY MAP u A 1 6. CONCLUSIONS 1 6.1. Compliance with Standards All computations that have been completed within this report are in compliance with the City of Fort Collins Erosion Control Reference Manual for Construction Sites and the Storm Drainage Design Criteria Manual. No variances are required for the project. 6.2. Drainage Concept The proposed drainage concepts presented in this report, and on the construction plans, adequately provide for stormwater detention and extended water quality treatment of the proposed site. Conveyance elements have been designed to convey on -site runoff to the proposed detention ponds and to minimize future maintenance. If, at the time of construction, groundwater is encountered, a Colorado Department of Health Construction Dewatering Permit will be required. 7. REFERENCES 1. City of Fort Collins, "Storm Drainage Criteria Manual", (SDCM), dated March ' 1999. 2. Urban Drainage and Flood Control District, "Urban Storm Drainage Criteria Manual", Volumes 1 and 2, dated June 2001, and Volume 3 dated September 2001. 5 I Basin 4 (0.04 acres) is located in the southeastern corner of the site and contains mainly landscape area. Runoff from this basin will surface flow to Shields Street. Runoff from Basin 4 is less than 0.1 cfs for the 10-year minor storm and 0.1 cfs for the 100-year major storm. 4.3. Drainage Summary rDrainage facilities located outside of the right-of-way (including the water quality and detention ponds, proposed storm sewer systems, and the pond outlets) will be maintained by the owners of the property. All on -site runoff, except for a small amount of landscape area, will be routed to the proposed on -site detention ponds. The amount of runoff leaving the site undetained is approximately 0.1 cfs for the 100-year storm. The proposed release rate from the on -site detention pond is 0.6 cfs for the 100-year storm. The allowable release rate is equal to the 2-year historic runoff (0.7 cfs) minus the undetained runoff (0.1 cfs). ' S. EROSION CONTROL 5.1. General Concept This site lies within the Moderate Rainfall and Wind Erodibility Zone per the City of Fort ' Collins and into. adjacent properties. Potential also exists for tracking of mud onto existing streets which could then wash into existing storm systems. The required performance standard for the site is 80.5%. During construction and after paving, this figure has been exceeded with the use of silt fence, inlet filters, and straw bales. All erosion control calculations are included in Appendix D of this report. The erosion control escrow amount is $5,000. 5.2. Specific Details To limit the amount of silt leaving the site several erosion control measures shall be implemented during construction. All inlets (existing and proposed) shall be protected with gravel filters, straw bales will be used where appropriate, and the north, south, and east boundaries shall have silt fence installed. A vehicle tracking pad shall be installed at the northwest corner of the site in order to control the mud being tracked onto the existing pavement. During overlot grading, disturbed areas shall be kept in a roughened condition and watered to reduce wind erosion. I 3.4. Hydraulic Criteria All hydraulic calculations within this report have been prepared in accordance with the City of Fort Collins Drainage Criteria and are included in Appendix B of this report. 4. DRAINAGE FACILITY DESIGN 4.1. General Concept All of the runoff from this site, with the exception of a small amount of landscape area (Basin 4) drains to one of the proposed on -site detention ponds. The proposed detention ponds will be linked hydraulically by proposed storm pipes and are being modeled as a single detention pond. 4.2. Specific Flow Routing A summary of drainage patterns for each basin is provided in the following paragraphs. Basin 1 (0.42 acres) is located in the southern half of the site and includes the majority of the proposed building, as well as parking, sidewalks, and landscaping. Runoff from the building will be conveyed to Storm 2 via a proposed roof drain pipe. The remainder of ' runoff drains to the north to a proposed storm inlet. From there, runoff is piped to Detention Pond IA. A small amount of parking lot detention is included in this basin. Runoff from Basin 1 is 1.7 cfs for the 10-year storm and 4.2 cfs for the 100-year storm. Basin 2 (0.37 acres) is located in the northern portion of the site and includes the remainder of the parking area and Detention Pond IA. Runoff from this basin is conveyed to the detention pond via sheet flow and curb & gutter. From there, runoff is released into the existing storm sewer system west of the site. The proposed release from the site is 0.60 cfs. Runoff from Basin 2 is 1.4 cfs for the 10-year storm and 3.6 cfs for the 100-year storm. Basin 3 (0.08 acres) is located in the northeast comer of the site and contains Detention Pond 1B. Runoff from this basin is conveyed via surface flow to the detention pond. Detention Pond IA and 1B are linked hydraulically by Storm 1 and are being modeled as a single pond. Runoff is 0.1 cfs for the 10-year storm and 0.3 cfs for the 100-year storm. 1 3 2.2. Sub -basin Description ' This site currently drains to the east and into the adjacent street sections. With this development, on -site runoff will be routed to proposed detention ponds. This site is not impacted by off -site flows. Runoff from the adjacent streets will be contained in the street sections. Runoff from the Senior Center to the west is routed to the north and into a pair of existing storm inlets. Runoff from the Raintree Animal Hospital to the north is routed to a detention pond at the northwest corner of this site. The existing detention pond for the Raintree Animal Hospital is being removed with this development and is being relocated further west. The detention volume and release rate for this pond was taken from the Raintree Animal Clinic plans by Stewart & Associates (see Appendix Q. Refer to Section 4 of this report for a detailed narrative of the on -site basin flow routing. 3. DRAINAGE DESIGN CRITERIA 3.1. Regulations This report was prepared to meet or exceed the "City I of Fort Collins Storm Drainage Design Criteria Manual" specifications. Where applicable, the criteria established in the "Urban Storm Drainage Criteria Manual" (UDFCD), 2001 has been used. 3.2. Development Criteria Reference and Constraints The runoff from this site has been routed to conform to the requirements of the City Stormwater Department. Stormwater detention and extended water quality detention are required for the site and are being provided by two on -site detention ponds and some minor parking lot detention. ' 3.3. Hydrologic Criteria Runoff computations were prepared for the 2-year and 10-year minor and 100-year major ' storm frequencies utilizing the Rational Method. All hydrologic calculations associated with the basins are included in Appendix B of this report. Stormwater detention and extended water quality detention volumes were calculated using the methods recommended in the "Urban Storm Drainage Criteria Manual". All detention pond calculations are included in Appendix C of this report. 1 2 1. GENERAL LOCATION AND DESCRIPTION 1.1. Location The Home State Bank project is located in the Southeast Quarter of Section 22, Township 7 North, Range 69 West of the Sixth Principal Meridian, in the. City of Fort Collins, Larimer County, Colorado. See the location map in Appendix A. The project is located north of Drake Avenue at the northwest intersection of Shields Street and Raintree Drive. The project is bounded on the north by the Raintree Animal Hospital, on the east by Shields Street, on the south by Raintree Drive, and on the west by the Fort Collins Senior Center. 1.2. Description of Property The project consists of approximately 0.9 acres of land. The proposed site consists of a ' bank building, along with associated drives, parking, and walks. Access is obtained from the Fort Collins Senior Center parking lot on the west and the Raintree Animal Hospital parking lot on the north. The proposed site is not located within any City of Fort Collins or FEMA floodplain boundaries. The site is currently developed with a single family home, garage, shed, drives and walks. Existing vegetation consists mainly of trees and native grasses. The land currently slopes to the northeast at approximately 1%. Runoff from this site is currently released into the adjacent roadways via overland flow. 1 2. DRAINAGE BASINS AND SUB -BASINS 2.1. Major Basin Description The proposed development lies within the Spring Creek Basin. Both stormwater detention and extended water quality detention are provided for this site. Detention is being provided on -site by two proposed detention ponds and minor parking lot detention. All detention areas are hydraulically linked by proposed storm sewer pipes and are being treated as a single detention pond. The proposed 100-year release rate from the site is 0.7 cfs, which is equal to the historic 2-year runoff from the site. 1 i 1 ITABLE OF CONTENTS TABLEOF CONTENTS............................................................................................................... iii 1. GENERAL LOCATION AND DESCRIPTION 1.1 Location...................................................................................................................1 1.2 Description of Property ............................................................................................1 2. DRAINAGE BASINS AND SUB -BASINS 2.1 Major Basin Description..........................................................................................1 2.2 Sub -Basin Description.............................................................................................2 3. DRAINAGE DESIGN CRITERIA 3.1 Regulations..............................................................................................................2 .3.2 Development Criteria Reference and Constraints....................................................2 3.3 Hydrologic Criteria..................................................................................................2 3.4 Hydraulic Criteria....................................................................................................3 4. DRAINAGE FACILITY DESIGN 4.1 General Concept.......................................................................................................3 4.2 Specific Flow Routing............................................................ :................................ 3 4.3 Drainage Summary ...................................................................................................4 5. EROSION CONTROL 5.1 General Concept......................................................................................................4 5.2 Specific Details.......................................................................................................4 6. CONCLUSIONS 6.1 Compliance with Standards..........................................................I.........................5 6.2 Drainage Concept.....................................................................................................5 7. REFERENCES....................................................................................................................5 t' APPENDICES A Vicinity Map B Hydrologic and Hydraulic Computations C Detention Pond Calculations D Erosion Control Calculations E Figures and Tables 1 North Star �Awo, design, inc. t March 1, 2005 IBasil Hamdan City of Fort Collins Stormwater 700 Wood Street Fort Collins, CO 80522-0580 RE: Final Drainage and Erosion Control Report for Home State Bank Dear Basil, I am pleased to submit for your review and approval, this Finaly Drainage & Erosion Control Report for Home State Bank. I certify that this report for the drainage design of Home State Bank was prepared in accordance with the criteria in the City of Fort Collins Storm Drainage Manual. I appreciate your time and consideration in reviewing this submittal. Please call if you have any questions. Prepared by: Reviewed By: n Shane Boyle, EIT Patricia Kroetch, PE 700 Automation Drive, Unit I Windsor, Colorado 80550 970-686-6939 Phone • 970-686-1 1 88 Fax FINAL DRAINAGE AND EROSION CONTROL REPORT HOME STATE BANK Prepared for: STEVE FORBES HOME STATE BANK FORT COLLINS, CO Prepared by: North Star Design 700 Automation Drive, Unit I Windsor, Colorado 80550 (970)686-6939 March 1, 2005 Job Number 238-01