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HomeMy WebLinkAboutPROSPECT/1-25 ODP - 20-03 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORT1 0Sherry D>'irr A,rrjlmt• 'A� � I A L_a FLOODING EFFECTS FROM SHERRYDRIVE TOF OVERFLOW kILED JDY EAST LIMIT OF STUDY 1, a _t ROAD i I CORPORATEL CORPORATE LIMITS To determine if flood insurance is available, contact an insurance agent or call the National Flood Insurance Program at (800) 638-6620. Q APPROXIMATE SCALE IN FEET Boo 0 600 NATIONAL FLOOD INSURANCE PROGRAM FIRM FLOOD INSURANCE RATE MAP CITY OF FORT COLLINS, COLORADO LARIMER COUNTY (SEE MAP INDEX FOR PANELS NOT PRINTED) COMMUNITY -PANEL NUMBER 080102 0016 C MAP REVISED: MARCH 18, 1996 Federal Emergency Management Agency I n N_ U N d O n d I d rn U U DATE: 6/10/03 SCALE: 1" = 1000' DRAWN BY: PPK j JOB NO.: 114-14 PROSPECT / 1-25 OVERALL DEVELOPMENT PLAN VICINITY MAP North Star ',► design, inc. 1194 W. Ash Street, Suite B Windsor, Colorado 80550 Phone: 970-686-6939 Fax: 970-686-1188 I APPENDIX LOCATION MAPS 1 t] ;' 1—a I I I 5. REFERENCES ' "Storm 1. City of Fort Collins, Drainage Criteria Manual", (SDCM), dated March, 1986. ' 2. "Final Drainage Erosion Control Report for Clydesdale Park, P.U.D." by and JR Engineering, Inc. dated June 9, 2000 3. Box Elder Creek Master Drainage Plan i 1 1 1 1 1 5 t I conveyance from this site has been identified. Negotiations with the ditch companies will be required to allow detention release to enter these conveyances as the historic runoff has done. These negotiations will occur during the design phase of the PDP. 1 4. CONCLUSIONS 1 4.1 Compliance with Standards I 1 [1 All computations in conjunction with preliminary and final development plans (PDP and FDP) completed for the ODP areas shall be in compliance with the City of Fort Collins Storm Drainage Design Criteria Manual and the Erosion Control Reference Manual for Construction Sites. 4.2 Drainage Concept The Overall Development Plan area shall be designed to meet the criteria set forth in the Manuals noted above. Basins 2, 3, 4 and 5 will require detention prior to release into existing conveyance systems. All runoff from the ODP area is proposed to be conveyed to Boxelder Creek or conveyed in the existing inlet ditch system to the Cache La Poudre River. 4 adopted by the City of Fort Collins on March 26, 1999. The basins in the ODP area will also be required to provide water quality enhancement in conjunction with the drainage design of each basin. 3.2 Basin Descriptions Basin 1 is located at the northwest corner of the site and contains approximately 5 acres. Boxelder Creek flows through this basin and, because of the close proximity to the Creek, it is proposed to release into the Creek without providing detention. A majority of this basin is located in the Boxelder Creek FEMA Flood Plain as designated on the floodplain maps and shown on the Conceptual Drainage Plan for the Prospect / I-25 ODP. Basin 2 is located along the east portion of the site and contains approximately 18 acres. ' This basin is being proposed as large lot residential development. It is proposed to provide detention and water quality extended detention in this basin and release to the south and into the Poudre Reservoir Inlet Ditch. The detention pond will release into this Ditch at a 2 year historic rate. Basin 3 contains approximately 64 acres and contains the majority of the industrial zone in the northern portion of the ODP area. This basin will provide detention and water quality extended detention and release at the 2 year historic rate into the Poudre Reservoir Inlet Ditch. Basin 4 contains approximately 11 acres and is located in the southwest portion of the ODP area and is south and west of the existing frontage road. This basin will be developed with uses allowed in the Commercial Zoning. This basin will provide detention and water quality extended detention and release at the 2 year historic rate under the frontage road and into the Lake Canal Irrigation Ditch. Basin 5 is located in the southwest portion of the site and contains approximately 19 acres. This basin is adjacent to the Lake Canal Ditch on its south side. The runoff from this site will be detained and be released at the 2 year historic rate. Water quality extended detention will also be provided for this basin. It is proposed with this ODP that Basins 2, 3, 4 and 5 will release into the Cache La Poudre Reservoir Inlet Ditch and the Lake Canal Irrigation Ditch. No other downstream 3 I The site is planned for approximately 31 acres of commercial development, 20.5 acres of residential development (urban estates) and 84 acres of industrial development. Specific layouts for these areas will be determined when final development plans are proposed. 1.2 Purpose of Report The purpose of this report is to present a conceptual plan for managing stormwater and establish criteria that will be utilized when final development plans for the property in the Overall Development Plan (ODP) area are completed. This report will also identify stormwater issues that will affect the design and layout of the site and need to be addressed with the final design plans for this site. 2. DRAINAGE BASINS AND SUB -BASINS 2.1 Major Basin Description The proposed ODP area lies within the Boxelder Creek Master Drainage Area. Drainage ' reports have been completed for the developments surrounding the proposed ODP including the Interchange Business Park, the Waterdale, Clydesdale and Kitchell residential developments to the north and east and the Homestead Estates and the Paradigm development to the south. 2.2 Sub -basin Description ' The ODP area has been divided into five basins and shown on the Conceptual Drainage Plan. Basins 2 through 5 will provide detention to the 2 year historic release rate and all basins will provide water quality features which may include extended detention. 1 3. DRAINAGE DESIGN CRITERIA 3.1 General Concept In general, the drainage design of the areas in this ODP will be required to conform to the previously completed drainage studies in the area. The drainage design of the ODP area will be required to accommodate the Rainfall Intensity -Duration -Frequency curve data 2 r 1. GENERAL LOCATION AND DESCRIPTION 1.1 Location and Description of Property The subject property is located at the northeast comer of the intersection of Prospect Road and Interstate 25. The property contains a total of approximately 135.5 acres. The entire property is located in the Southwest Quarter of Section 15, Township 7 North, Range 68 West of the Sixth Principal Meridian, in the City of Fort Collins, Larimer County, Colorado. The project is bounded on the east property line by the existing Kitchell development and the future Fort Collins high school site. An undeveloped Larimer County parcel bounds the site on the north. The project is bounded by the existing frontage road on the west and Prospect Road on the south. The Poudre Reservoir Inlet Ditch and the Lake Canal Irrigation Ditch flow through the southern portion of the site. ' The property is undeveloped and is currently being farmed. A small portion of the property at the northwest corner is in the Boxelder Creek FEMA 100 year Flood Plain and slopes to the northwest into Boxelder Creek (Refer to the Flood Plain Map in the Appendix). The remainder of the property slopes to the south at approximately 0.5%. The 100 year Boxelder Creek Flood Plain as mapped by the City of Fort Collins covers approximately 70 percent of the site. It is proposed that the 100 year flows predicted by the City of Fort Collins model be conveyed through the site in a channel. The modeling required to size and design this channel and modification to the City of Fort Collins 100 year floodplain will be completed with the PDP and FDP for this site. The conceptual routing for this channel is shown on the ODP Conceptual Drainage Plan. ' The 100 year flood volumes flowing through this site are anticipated to be approximately 4000 cfs based on the City of Fort Collins model. The proposed channel would capture the flows at the northwest corner of the site near Boxelder Creek, convey these flows south along the frontage road and east along the Poudre Reservoir Inlet Ditch. The flows ' would then be forced over the Poudre Reservoir Inlet Ditch and the Lake Canal Irrigation Ditch assuming that both conveyances are flowing full which will emulate the modeled condition. The flow will once again be captured on the south side of the ditches and conveyed south across the frontage road and released to overtop Prospect Road at the modeled location with a small pipe under Prospect Road for minor storm flows. 1 I TABLE OF CONTENTS TABLEOF CONTENTS............................................................................................................... iii 1. GENERAL LOCATION AND DESCRIPTION 1.1 Location and Description of Property......................................................................1 1.2 Purpose of Report ....................................................................................................2 2. DRAINAGE BASINS AND SUB -BASINS 2.1 Major Basin Description..........................................................................................2 2.2 Sub -Basin Description.............................................................................................2 3. DRAINAGE DESIGN CRITERIA 3.1 General Concept.......................................................................................................2 3.2 Basin Description.....................................................................................................3 4. CONCLUSIONS 4.1 Compliance with Standards....................................................................................4 4.2 Drainage Concept.....................................................................................................4 5. REFERENCES....................................................................................................................5 iii North Star �avow design, inc. ' June 10, 2003 ' Basil Hamdan City of Fort Collins Stormwater 700 Wood Street ' Fort Collins, CO 80522-0580 RE: Overall Drainage Concept for the ' Overall Development Plan for Prospect / I-25 Dear Basil, ' I am pleased to submit for your review and approval, this Overall Drainage Concept for the ' Overall Development Plan for Prospect / I-25. I appreciate your time and consideration in reviewing this submittal. Please call if you have any questions. 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