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Home My WebLink AboutPROSPECT INDUSTRIAL PARK, MIDPOINT SELF-STORAGE - PDP - 28-98D - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTI I I I D 1 ® PROSPECT ROAD \ • ' it o �< I `` 1 1 ' 40 0 o /1 W Z z j\ J 1' H DRAKE ROAD I 1 I P I I 0 la 0 I� W IJ W I N PROJECT SITE SHEET 1 OF 1 DATE: 06/10/03 MIDPOINT SELF STORAGE SUBDIVISION VICINITY MAP %North Star -��, design, inc. 700 Automation Drive, Unit I Windsor, Colorado 90550 PhoJOB Fax: n970-6 611839 8 SCALE: 1" = 1500' DRAWN BY: SB NO.: 202-01 APPENDIX A VICINITY MAP n 7. REFERENCES 1. City of Fort Collins, "Storm Drainage Criteria Manual", (SDCM), dated March 1999. 2. JR Engineering, "Final Drainage and Erosion Control Report, Midpoint Self - Storage Solutions", dated July 6, 2001. 3. Stewart & Associates, "Prospect East Industrial Overall Drainage Plan", dated June 23, 1988. 4. Urban Drainage and Flood Control District, "Urban Storm Drainage Criteria Manual", Volumes 1 and 2, dated June 2001, and. Volume 3 dated September 2001. 7 6. CONCLUSIONS 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 quality treatment of the proposed site. Conveyance elements have been designed to convey required flows to the existing borrow pond 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. 6 I ' Basin SP-2 contains the future south side of Sharp Point Drive. Upon the completion of Sharp Point Drive, a 5' Type R inlet will be constructed and connected to Storm 2. This inlet will collect Basin SP-2 runoff and pipe it to the existing pond. In the interim, runoff will be collected in the existing pan or sheet flow into the pond, which is the existing flow pattern. Runoff from this basin is 1.8 cfs for the minor storm and 4.7 cfs for the major storm. 4.3. Drainage Summary Drainage facilities located outside of the right-of-way (including the water quality ponds, existing and proposed storm drain systems, and the pond outlets) will be maintained by the owners of the property. 5. 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 75.6%. During construction and after paving, this figure has been exceeded with the use of silt fence, inlet filters, straw bales, and by using the water quality pond as a sediment trap during construction. All erosion control calculations are included in Appendix E of this report. The erosion control escrow amount is $6,400. 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 south and east boundaries shall have silt fence installed. Vehicle tracking pads shall be installed at the connection to Midpoint Drive to control the mud being tracked onto the existing pavement. During overlot grading, disturbed areas are to be kept in a roughened condition and watered to reduce wind erosion. The water quality ponds will be used as rsediment traps during construction. I 5 Basin 104 of the proposed site will be routed to south to WQ Pond 1. This pond will be incised into the berm and will have a water quality outlet structure mounted in a headwall. A 2' concrete pan will convey the clean water to the existing pan and swale. There will be no pipe outlet for the pond. The wall will overtop in larger storms and will flow into the existing pan and swale and the runoff will be conveyed to the existing pond. 41. Specific Flow Routing A summary of the drainage patterns within each basin is provided in the following paragraphs. Off -site basins 101, 102, and OS-3 are described in the report by JR Engineering (refer to Appendix F). Basin 103 includes the northern portion the site, including buildings, drives, and WQ Pond 1. This basin drains northeast via concrete pans to WQ Pond 1. From there, runoff is combined with runoff from Midpoint Storage Phase 1, Basin 101 and is conveyed via an existing storm pipe to the existing borrow pond. Runoff from Basin 103 is 5.4 cfs for the 10-year storm and 14.0 cfs for the 100-year storm. The City has specified that no additional flows go to Midpoint Drive. The proposed design meets this requirement. Basin 104 includes southern portion of the site, including buildings, drives, and WQ Pond 2. This basin drains south via concrete pans to WQ Pond 2. From there, runoff is released into the existing drainage swale adjacent to the Colorado & Southern Railroad tracks. This site is required to build the west curb and gutter of Sharp Point Drive. This requires that fill be placed over the existing pan. In the interim, a 24" RCP culvert will be placed under the fill and will connect the existing pan. This pipe will work, with flows above the pipe capacity going south around the new fill. When the road is constructed to the railroad tracks, all flows will need to be piped. A storm sewer (Storm 1A) has been designed. This future pipe will require an area inlet and will be placed lower than the existing pan and will discharge to the existing pond. The 36" storm sewer is not part of this construction. Runoff from Basin 104 is 6.1 cfs for the 10-year storm and 16.0 cfs for the 100-year storm. ' Basin SP-1 contains the north side of Sharp Point Drive and some landscaping areas. This basin is collected in a proposed 5' Type R inlet and is piped to the existing pond. Runoff is 1.7 cfs for the 10-year storm and 4.7 cfs for the 100-year storm. 1 4 3.3. Hydrologic Criteria ' Runoff computations were prepared for the 10-year minor and 100-year major storm frequency utilizing the Rational Method. All hydrologic calculations associated with the basins are included in Appendix B of this report. Water quality volume was calculated using the method recommended in the "Urban Storm Drainage Criteria Manual". All water quality calculations are included in Appendix D of this report. 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 C of this report. The existing storm sewer system was analyzed with this design. Basin 103 releases into an existing storm pipe designed by JR Engineering. The design included estimated runoff from Midpoint Storage Phase 2. According to the July 2001 report by JR Engineering, the pipe has the capacity to convey 73.9 cfs. A composite analysis of the flow to the pipe was conducted using the Rational Method. With the included runoff from Midpoint Storage Phase 2, subbasin 103, the peak runoff in the pipe is 24.6 cfs. According to James H. Stewart & Associates (June 1978), the existing concrete pan and swale has a capacity of 88.8 cfs. A composite analysis of the basins releasing into the swale was conducted using the Rational Method. With the included runoff from ' Midpoint Storage Phase 2, subbasin 104, the peak runoff in the swale is 50.5 cfs. 4. DRAINAGE FACILITY DESIGN 4.1. General Concept All of the runoff from this site and the adjacent areas drains northeast to the existing pond ' via gutters, storm pipes, and concrete pans. Basin 103 of the proposed site will be routed northeast to WQ Pond 1. The runoff will then be combined with runoff from Midpoint ' Storage Phase 1, Basin 101 and will be conveyed via an existing storm pipe to the existing pond. k3 2. DRAINAGE BASINS AND SUB -BASINS 2.1. Major Basin Description The proposed development lies within the Poudre River Drainage Basin. There is no City of Fort Collins master plan for the Poudre River Drainage Basin and detention is not required for this basin. However, releases from this site must not negatively impact downstream drainage facilities and adequate conveyance to a major drainage outfall must be shown. 2.2. Sub -basin Description This site drains via storm sewer pipes and the existing concrete pan and drainage swale to the existing pond east of the site. There are two drainage basins for the proposed site. Basin 103 runoff flows into the water quality pond on the north end of the site (WQ Pond 1) and is combined with storm flow from Phase 1, Basin 101, and is then conveyed into the existing borrow pond. Basin 104 runoff flows into the water quality pond on the south end of the site (WQ Pond 2) and is released into the existing concrete pan and swale. See Section 4 of this report for a more detailed explanation of subbasin flows. Excerpts from "Final Drainage and Erosion Control Report" by JR Engineering are included in Appendix F of this report. The Phase I Drainage Plan is included in the back pocket. 3. DRAINAGE DESIGN CRITERIA 3.1. Regulations This report was prepared to meet or exceed the "City 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. Detention is not proposed for this site. Water quality facilities are required for the site. 2 1. GENERAL LOCATION AND DESCRIPTION 1 1.1. Location Midpoint Self Storage is located in northeast Fort Collins. This project is located in the North Half of Section 20, Township 7 North, Range 68 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 south of Prospect Road on Sharp Point Drive at the intersection of Sharp Point Drive and Midpoint Drive. The project is bounded on the north by Midpoint Drive, on the east by the Midpoint Storage Phase 1, on the south by the Colorado & Southern Railroad, and on the west by City of Fort Collins property (future Sharp Point Drive). 1.2. Description of Property ! The project consists of approximately 3.5 acres of land. The proposed site consists of self storage buildings and associated drives. Access is gained through Midpoint Storage Phase 1, with emergency accesses from existing Midpoint Drive and future Sharp Point Drive. The Cache La Poudre River is located to the east of the site. The proposed site is not located within the City of Fort Collins or FEMA floodplain boundaries for the Poudre River. Existing vegetation consists mainly of native grasses and small trees. The land currently slopes to the southeast at approximately 1%. The site is zoned I for Industrial Zoning District. There is an existing pond to the east of the proposed site which will be used as a release point for on -site runoff. The pond is part of the Cache La Poudre'River flood plain and drains through a series of ponds into the Poudre River. There is a 2' concrete pan and drainage Swale that collects runoff from the properties to the northwest of the Midpoint Storage site and routes the flows to the existing pond. Runoff from a portion of the proposed project will be combined with flows in the existing wpan and swale prior to being released into the pond. 1 TABLE 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..........................................................................................2 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 ......................... :................................................................... :.... 3 3.4 Hydraulic Criteria....................................................................................................3 4. DRAINAGE FACILITY DESIGN 4.1 General Concept.......................................................................................................3 4.2 Specific Flow Routing.............................................................................................4 4.3 Drainage Summary ...................................................................................................5 5. EROSION CONTROL 5.1 General Concept......................................................................................................5 5.2 Specific Details........................................................................................................5 6. CONCLUSIONS 6.1 Compliance with Standards....................................................................................6 6.2 Drainage Concept.....................................................................................................6 1 7. REFERENCES...............................................................:....................................................7 IAPPENDICES A Vicinity Map B Hydrologic Computations C Hydraulic Calculations D Water Quality Pond Sizing E Erosion Control Calculations F Excerpts from Other Reports G Figures and Tables iii 1 1 North Star rl*,., design, inc. I I June 10, 2003 Basil Hamdan City of Fort Collins Stormwater 700 Wood Street Fort Collins, CO 80522-0580 RE: Final Drainage and Erosion Control Report for Midpoint Self Storage Subdivision IDear Basil, 1 I am pleased to submit for .your review and approval, this Revised Final Drainage & Erosion Control Report for Midpoint Self Storage Subdivision. I certify that this report for the drainage design of Midpoint Self Storage Subdivision 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: 04'rj- 4� Shane Boyle, EIT North Star Design, Inc. Reviewed By: 342 Oro �s�ONAL ENG\�� Michael Oberlander, P] North Star Design, Inc. 700 Automation Drive, Unit I Windsor, Colorado 80550 970-686-6939 Phone . 970-686-1 1 88 Fax FINAL DRAINAGE AND EROSION CONTROL REPORT MIDPOINT SELF STORAGE SUBDIVISION Prepared for: DCB Construction Company, Inc. 909 East 62"d Avenue Denver, CO 80216 Prepared by: North Star Design 700 Automation Drive, Unit I Windsor, Colorado 80550 (970)686-6939 June 10, 2003 Job Number 202-01