The URL can be used to link to this page

Home My WebLink AboutCAMBRIDGE LOFTS APARTMENTS - FDP - 6-03D - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTIr C�� W. ULBER YST Ll PROJI LOCA AT I N IN1161 W PLUM ELIZABETH STR ET --------------- h O W Z HORSETOOTH ROAD h SHEET 1 OF 1 DATE: 12/3/03 CAMBRIDGE LOFTS MINOR SUBDIVISION VICINITY MAP North Star design, inc. 700 tomaton Coloration ve80 SOt I Phone: 970-686-6939 SCALE: 1' - 2000• DESIGNED BY: TLN JOB NO.: 136-02 Fax: 970.686-1188 APPENDIX A VICINITY MAP I I t I 7. 6.3 Erosion Control Concept Since the site is less than 5.0 acres, a NPDES permit is not required. During construction, erosion control shall be maintained to minimize erosion on this site and transport of silt downstream. REFERENCES 1. City of Fort Collins, "Storm Drainage Criteria Manual", (SDCM), dated March, 1986. 2. Urban Drainage and Flood Control District, "Urban Storm Drainage Criteria Manual", Volumes 1 and 2, dated June 2001, and Volume 3 dated September, 1999. damage resulting from dust originating from his operations under these plans, on right-of- way or elsewhere. 5.4 . Tracking Mud Wherever construction vehicles access routes intersect paved public roads, provisions shall be made to minimize the transport of sediment (mud) by runoff or vehicles tracking onto the paved surface. The contractor will be responsible for clearing tracked mud on a ' daily basis. 5.5 Maintenance All temporary and permanent erosion and sediment control practices must be maintained ' and repaired as needed to assure continued performance of their intended function. Silt fences will require periodic replacement. Maintenance is the responsibility of the ' contractor. 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. 6.2 Drainage Concept The proposed drainage concepts presented in this report and on the construction plans maintain the existing drainage patterns and the existing imperviousness for this site. Conveyance elements have been designed to pass required storm flows 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. i 4.3 Drainage Summary The existing and proposed drainage facilities located outside the right of way will be maintained by the site owner or the Home Owner's Association. 4.4 Variance Requests No variances are being requested at this time. 5. EROSION CONTROL 5.1 General Concept This site lies within the Moderate Rainfall and Wind Erodibility Zone per the City of Fort ' Collins Zone Maps. The potential exists for silt movement from the site and into Spring Creek. Potential also exists for tracking of mud onto existing streets which could then wash into existing storm systems. All erosion control measures necessary to minimize sediment transport have been shown on the Erosion Control Plan. The required performance standard for the site is 77.1%. During construction and after paving, this figure has been exceeded with the use of silt fence and inlet filters on the sidewalk culverts. All erosion control calculations are included in Appendix D of this report. The erosion control escrow amount is $3105. 1 5.2 Specific Details To limit the amount of silt leaving the site several erosion control measures shall be implemented during construction. All boundaries shall have silt fence installed and all streets shall be cleaned to eliminate mud being tracked onto the street. During demolition, disturbed areas are to be kept in a roughened condition and watered to reduce wind erosion. 5.3 Dust Abatement During the performance of the work required by these plans, the contractor shall carry out proper efficient measures wherever and as necessary to prevent dust nuisance, which has 3.4 Hydraulic Criteria ' All preliminary hydraulic calculations within this report have been prepared in accordance with the City of Fort Collins Drainage Criteria and are included in the Appendix of this report. The sidewalk culverts and the concrete channel at the southeast corner of the site were sized to carry the 100 year storm event. 4. DRAINAGE FACILITY DESIGN 4.1 General Concept All of the runoff from this site currently drains to the adjacent streets and is either ' collected in the storm system on Plum Street or Shields Street. Both storm systems convey the runoff to Spring Creek. There is currently no detention or water quality provided on site. It is proposed that a similar runoff pattern be maintained with the redevelopment of the east portion of this site. 4.2 Specific Flow Routing A summary of the drainage patterns within each basin is provided in the following paragraphs. Basin 1 contains the existing east parking lot and the proposed building. The runoff from this basin currently flows to Shields Street via the drive entrances. These drive entrances will be removed with the proposed redevelopment and the, water will be directed to the southeast corner of the parking lot, into a concrete channel and into Shields Street. Basin 2 contains a portion of the existing buildings and parking lot on the east and south sides of these existing buildings. It is proposed to add twelve parking stalls in this area and reinstall a fire lane. Runoff from this basin flows east into Basin 1. Basin 3 contains the eastern half of the building and the existing and proposed walks and landscape between the building and Shields Street. Runoff from this basin will enter Shields Street directly via overland flow or minor sidewalk culverts. This site drains to Shields Street or Plum Street and is conveyed in the streets to the storm system. This storm system carries the water east and south under Shields Street to Spring Creek. 1 3. DRAINAGE DESIGN CRITERIA 3.1 Regulations This report was prepared to meet or exceed the "City of Fort Collins Storm Drainage IDesign Criteria Manual' specifications. Where applicable, the criteria established in the "Urban Storm Drainage Criteria Manual" (CTDFCD), .1984, developed by the Denver Regional Council of Governments, 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. Because there is no increase in impervious area on this site, detention and water quality are not proposed for this site. The majority of the site will be routed to the southeast comer of the site and will be conveyed via a concrete channel and sidewalk culverts to Shields Street. The building, sidewalk area and the landscaped area on the east side of the site adjacent to Shields will discharge directly to the adjacent streets. 3.3 Hydrologic Criteria Runoff computations were prepared for the 2-year minor and 100-year major storm frequency utilizing the rational method. All preliminary hydrologic calculations associated with the basins are included in the Appendix of this report. Standard Form 8 (SF-8) provides time of concentration calculations for all sub -basins. Standard Form 9 (SF-9) provides a summary of the design flows for all Sub -basins and Design Points associated with this site. i yN 1 1. GENERAL LOCATION AND DESCRIPTION 1.1 Location The Cambridge House Lofts is located in Old Town Fort Collins. This project is located in the Northeast Quarter of Section 15, 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 the Appendix. The project is located in the southwest corner of the intersection of Plum Street and Shields Street. The project is bounded on the north by a church and Plum Street, on the east by the Shields Street and on the south and west by existing development. 1.2 Description of Property The entire project consists of approximately 3.4 acres of land. This property currently has 6 existing residential buildings and parking lot. The land currently slopes to the north and southeast at a range of approximately 0.5% to 1%. The existing buildings will remain without modification. The proposed redevelopment consists of removal of existing parking, construction of a single building on the east end of the site, replacement of a portion of the parking and addition of parking at the south end of the existing buildings. The site currently drains into Plum Street and into Shields Street. It is not proposed to modify the area that drains to Plum Street; therefore this area was not reanalyzed. The area that drains to Shields is being modified and is therefore being reanalyzed with this report. 2. DRAINAGE BASINS AND SUB -BASINS 2.1 Major Basin Description The proposed development lies within the Spring Creek Master Drainage Basin. This site is not located in a 100-year floodplain or in a `Flooded Area' designated in Figure 4 of the above reference report. =M 2.2 Sub -basin Description ' TABLE OF CONTENTS TABLEOF CONTENTS.............................................................................................................................iii 1. GENERAL LOCATION AND DESCRIPTION ' 1.1 Location...............................................................................................................................1 1.2 Description of Property ........................................................................................................ I 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 C>�eria..............................................................................................................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 4.4 Variance Requests...............................................................................................................4 5. EROSION CONTROL 5.1 General Concept .: .................. :............................................................................................ 4 5.2 Specific Details....................................................................................................................4 5.3 Dust Abatement...................................................................................................................4 5.4 Tracking Mud......................................................................................................................5 5.5 Maintenance........................................................................................................................5 6. CONCLUSIONS 6.1 Compliance with Standards................................................................................................5 6.2 Drainage Concept................................................................................................................5 6.3 Water Quality and Erosion Control Concept.......................................................................6 7. REFERENCES................................................................................................................................. APPENDICES A Vicinity Map B Hydrologic & Hydraulic Calculations C Erosion Control Calculations D Figures and Tables 1 North Star rlAfto, design, inc. April 20, 2004 Basil Hamdan City of Fort Collins Stormwater 700 Wood Street Fort Collins, CO 80522-0580 RE: Final Drainage and Erosion Control Study for the Cambridge House Lofts ■ Dear Basil, r I am pleased to submit for your review and approval, this revised Final Drainage and Erosion Control Study for the Cambridge House Lofts. I certify that this report for the drainage design 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. 700 Automation Drive, Unit I Windsor, Colorado 80550 970-686-6939 Phone . 970-686-1 188 Fax FINAL DRAINAGE AND EROSION CONTROL STUDY For CAMBRIDGE HOUSE LOFTS Prepared for: Vantage Properties West Plum Street Fort Collins, CO 80521 Prepared by: North Star Design 700 Automation Drive, Unit I Windsor, Colorado 80550 (970)686-6939 April 20, 2004 Job Number 136-02