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HomeMy WebLinkAboutPVH HEALTH SYSTEMS, HARMONY CAMPUS, 4TH FILING, MOB (REDSTONE) - FDP - 32-98K - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTVICINITY MAP SCALE: 1 " = 1500' VICINITY MAP 14 1. Storm Drainage Design Criteria and Construction Standards by the City of Fort Collins, Colorado, May 1984, Revised January 1997. 2. Erosion Control Reference Manual for Construction Sites by the City ofFort Collins, Colorado, January 1991, Revised January 1997. 3. McClellands Basin 100-Year Master Plan Update, by Icon Inc., Fort Collins, 4. Final Drainage and Erosion Control Report Poudre Valley Health Systems Harmony Campus Infrastructure Project Development Plan, Fort Collins, Colorado, May 12, 2004. 12 All construction activities must also comply with the State of Colorado permitting process for Stormwater Discharges Associated with Construction Activity. A Colorado Department of Health NPDES permit has been obtained such that construction grading can continue within this development. VII. CONCLUSIONS A. Compliance with Standards All computations within this report have been completed in compliance with the City of Fort Collins Storm Drainage Design Criteria. The City of Fort Collins Storm water Utility will not maintain the on -site storm drainage facilities within the Poudre Valley Hospital site. The owners of the Poudre Valley Hospital site will maintain their on -site storm drainage facilities on a regular basis. B. Drainage Concept The proposed drainage concepts presented in this study and those shown on the final utility plans will adequately provide for the transmission of developed on -site runoff to the proposed detention ponds. The combination of on -site street capacities and the on -site storm sewer system will provide for the developed flows to reach the proposed detention ponds. The sizes, locations and release rates of these ponds will allow the Poudre Valley Hospital site to develop in conformance with the McClellands Basin Drainage Master Planning concepts accepted by the City of Fort Collins. If groundwater is encountered at the time of construction, a Colorado Department of Health Construction Dewatering Permit will be required. C. Storm Water Quality Storm water quality will be addressed through the use of gravel inlet filters, erosion control fence, existing grass -lined detention ponds, and extended detention in Pond 593. D. Erosion Control Concept The proposed erosion control concepts will adequately provide for the control of wind and rainfall erosion from the Redstone POB site. Through the construction of the proposed erosion control concepts, the City of Fort Collins performance standards will be met. 11 VI. EROSION CONTROL A. General Concept Silt fence and curb -cut protection will be utilized to minimize erosion on the Redstone POB site. Please see the Drainage and Erosion Control Exhibit located in the map pocket. The Redstone POB site lies within the Moderate Rainfall Erodibility Zone and the Moderate Wind Erodibility Zone per the City of Fort Collins zone maps. The potential exists for erosion problems during construction, and after construction until the disturbed ground is re -vegetated or paved. There should be minimal to no erosion problems after completion of construction. The computed Erosion Control Performance Standards (PS) before and after construction is 79.3 and 93.4 respectively. Furthermore, the effectiveness values during and after construction are 95.2 and 98.4 respectively. These computed values meet the City of Fort Collins requirements and can be seen in Appendix C. An erosion control escrow cost estimate of $17,753 (price includes 50% contingency) is also included in Appendix C. This represents the cost to re -seed and provide the required erosion control methods the site. B. Specific Details A silt fence will be installed prior to grading of the site, as shown on the drainage and erosion control plan. All other disturbed areas not in a roadway or greenbelt area shall have temporary vegetation seed applied within 30 days of initial disturbance. After seeding, a hay or straw mulch shall be applied over the seed at a rate of 1.5- tons/acre minimum, and the mulch shall be adequately anchored, tacked, or crimped into the soil. Those areas that are to be paved must have a 1-inch layer of gravel mulch applied at a rate of at least 135 tons/acre 30 days after overlot grading is completed. The pavement structure shall be applied within 30 days after the utilities have been installed. If the disturbed areas will not be built on within one growing season, a permanent seed shall be applied. After seeding, a hay or straw mulch shall be applied over the seed at a minimum rate of 1.5 tons/acre, and the mulch shall be adequately anchored, tacked or crimped into the soil. In the event a portion of the roadway pavement surface and utilities will not be constructed for an extended period of time after overlot grading, a temporary vegetation seed and mulch shall also be applied to the roadway areas as discussed above. HN Basin 53A accounts for a small, northern parking lot portion of the Redstone site, which will flow north and into the curb and gutter along Timberwood Drive (Private Drive). The runoff from basin 53A will flow east in the curb and gutter to an existing 5' Type R Inlet, on the south side of Timberwood Drive. UDInlet was used to check the capacity of the existing inlet. Basin 53A will add 1.2 cfs to the original 2.2 cfs from the Infrastructure Report. The existing inlet has capacity to take the additional 1.2 cfs flow from basin 53A (see calculations in Appendix B). Please refer to the PVHS Filing 2 Drainage and Erosion Control Report for more detailed information on basin 103, and Ponds 393 and 593. SWMM Model Please refer to the PVHS Filing 2 Drainage and Erosion Control Report. V. STORM WATER QUALITY A. General Concept Storm Water Quality will be provided through extended detention, presently provided by existing Pond 593. This pond was constructed with PVH Filing 2. B. Specific Details Best Management Practices (BMP) for the treatment of storm water runoff will be provided through the use of gravel inlet filters, erosion control fence, and the existing grass -lined detention ponds 393 and 593. Furthermore, pond 593 will provide extended detention through its outlet structure. Erosion control fence shall be installed where shown in the final plans. Gravel inlet filters shall be installed as shown on the erosion control plan. Erosion control calculations have been provided in Appendix C. E continue east and combine with flows from basin 203. A 4' curb cut at design point 203 will capture flows from basins 202-203 and convey the runoff east and into an existing inlet. The existing inlet conveys flows east and into the existing detention/inigation Pond 393. The runoff from the roof of the Redstone POB (basins 205, 207, 209, 211, 213, and 217-220) will be captured by a series of roof drains. The roof (basins 205, 207, 209, 211, 213) will drain to the north and be conveyed east in the proposed storm drain (STRM-A) in the landscaped area north of the building. Nyloplast inlets will be provided in sump areas (basins 210, 212, 214, 216) north of the building. These inlets will add flow to STRM-A. The combined flow from basins 205, 207, 209-214, and 216 will be routed northeast in STRM-A and into the existing 43" x 68" elliptical concrete pipe that carries flows east and into detention/irrigation Pond 393. UDSewer calculations have been provided in Appendix B for STRM-A and also the existing 43" x 68" elliptical pipe. The existing elliptical pipe has capacity to include the runoff from Storm A and will be minutely affected. The southern portions of the roof (basins 217-220) will drain to the south and be conveyed east in the proposed storm drain (STRM-B). STRM-B will discharge into a temporary retention basin. The 100-year rational flow in STRM-B is 3.83 cfs. Rather than releasing the flow overland, the flow will be retained on a temporary basis until construction of the next phase in the PVHS masterplan. Future construction will provide that STRM-B be tied -in to a future storm main, which will run south in basin 103 of the PVH Infrastructure. This connection will convey the 3.83 cfs south and east into Pond 593, where detention and water quality will be provided. The runoff from basin 230 (west side of the building) will be continue to follow the historic pattern and existing swale south and under the proposed sidewalk. A 2' concrete sidewalk culvert will be provided at design point 230 to allow the 1.5 cfs (100-yr) flow to pass under the walk and continue south overland. Likewise, the runoff from basin 231 (east and south side of the building) will flow south and east overland in its historic drainage pattern. The 100-year flow from basin 231 is 1.36 cfs so it is not anticipated that this flow has to be detained. It is important to note that water quality and detention for basins 230-231 is already provided for in Pond 593 of the Infrastructure. Basin 232 is shown for informational purposes only and is not a developed basin within the Redstone POB site. Basin 232 (17.98 acres) is the remaining area of basin 103 (22.26 acres) from the PVHS Infrastructure Report. The Redstone POB property accounts for 3.83 acres of basin 103, with an additional 0.45 acres accounted for in the drainage calculations due to offsite grading, primarily on the south and east sides of the property. The flows captured at these locations, will be ultimately conveyed east and into the existing detention/irrigation pond (Equalizer Pond 393), east of the parking lot. It is important to note that the equalizer pond (Pond 393) discharges flows south into an existing swale. This swale carries flows south and then east and into the existing detention pond (Pond 593 from the PVHS Infrastructure) in the southeast corner of the PVH Site. Furthermore, though the Healthy Living Center Site will increase impervious area (based on existing conditions) within basin 103, upsizing is not required due to the SWMM Model from the PVHS Filing 2 Report, which provides a detention pond (Pond 593) in the Southeast corner of the PVH Site. In the Master Plan, the Redstone POB site was planned to be a typical building and parking lot of about 88% imperviousness. However, the proposed Redstone site provides for 79% imperviousness, thus meeting the overall 80% imperviousness provided for in the SWMM model. The SWMM model provided for 80% imperviousness over the entire PVH Site. Water quality for the entire PVH site is provided for in Pond 593. It is important to note that Pond 593 is only partially constructed at this time. The current build -out of Pond 593 provides the required water quality and detention due to the development of the Redstone POB site. The remaining portion of Pond 593 will be constructed along with future developments within the PVH Site. B. Specific Details The Redstone POB site contains approximately 3.83 acres. Runoff from the site will be routed east into the existing detention/irrigation Pond 393. Pond 393 discharges excess runoff south and into an existing swale. The swale bends to the east at the south property line of the PVH site and carries flows into detention pond 593. It is important to again note that Pond 593 provides detention and water quality for the Redstone Site, not Pond 393. Pond 393 only passes the flows from the Redstone site through. Basin 201 of the Redstone POB site will flow west and will be captured by the existing 15' Type R Inlet (design point 201). The flow from basin 201 will join with flows from PVH Filing I (basins 1, 12, & 14-20) and will conveyed east in the existing 43" x 68" elliptical storm drain. UDInlet calculations are provided for in Appendix B and show the existing inlet can handle the runoff from basin 201. Meanwhile, runoff from basins 202-203 will be conveyed to its respective design point. A 2' curb cut with chase at design point 202 will allow storm flows to 7 III. DRAINAGE BASIN CRITERIA A. Regulations The City of Fort Collins Storm Drainage Design Criteria is being used for the subject site. B. Development Criteria Reference and Constraints The criteria and constraints from The McClellands Basin 100-Year Master Plan and the subsequent update, dated March 2000 by Icon Engineering will be utilized in this Drainage Study. The Poudre Valley Hospital site is currently being utilized as fallow agricultural land C. Hydrologic Criteria The SWMM hydrologic model that was previously used in the McClellands Basin 100-Year Master Plan Update by Icon Engineering has been utilized and updated in PVH Master Infrastructure report in order to analyze the hydrologic conditions of the proposed Redstone POB Site. Furthermore, rational calculations have been provided in Appendix B for the site, as well as curb cut and storm drain sizing using Flowmaster, UDInlet, and UDSewer. D. Hydraulic Criteria All calculations within this study have been prepared in accordance with the City of Fort Collins Storm Drainage Criteria and the PVHS Filing 2 Report. IV. DRAINAGE FACILITY DESIGN A. General Concept The purpose of this report is to address the storm drainage flows from the development of the Redstone POB site, in relation to the Master Drainage Plan contained in the PVHS Filing 2 Drainage Report, May 12, 2004. The Redstone POB site is contained within basin 103 of the PVHS Filing 2 Report (see Drainage Exhibit in Map Pocket). The Redstone POB site accounts for approximately 3.83 acres of the 22.26 acres in basin 103. The storm flows from the majority of the Redstone POB site will be conveyed to proposed area inlets in the green areas on the north side of the building and curb cuts within the parking lot. 0 FINAL DRAINAGE AND EROSION CONTROL REPORT FOR THE POUDRE VALLEY HEALTH SYSTEMS 4Tx FILING, REDSTONE POB FORT COLLINS, COLORADO I. GENERAL LOCATION AND DESCRIPTION A. Location The Poudre Valley Health Systems 4ch Filing site is located south of Harmony Road and east of Timberline Road in southeastern Fort Collins, Colorado. The site is shown on the Vicinity Map in Appendix A. More particularly, the site is situated in the northwesterly portion of Section 5, Township 6 North, Range 68 West of the Sixth P.M., City of Fort Collins, Larimer County, Colorado. B. Description of Property The Redstone POB site is located in the north portion of the PVH Site and accounts for approximately 3.83 acres of the 72.6 acres contained within the Poudre Valley Health Systems Harmony Campus Medical Center Filing 2. The Redstone POB site currently consists of fallow farmland, a detention/irrigation pond, and some landscaping on the west boundary. A private drive also extends along the north property line. The site generally slopes to the east at approximately 2.0%. II. DRAINAGE BASINS A. Major Basin Description The Redstone POB site lies entirely within the McClellands Basin. The project drainage is modeled in The McClellands Creek Master Drainage Plan Update (March 2000). Applicable portions of these studies are included in Appendix C, of the PVHS Harmony Campus Infrastructure Project Development Plan Drainage and Erosion Control Report, May 12, 2004. (See Major Basin Description in above Report) B. Sub -Basin Description (See PVHS Filing 2 Drainage Report) 5 APPENDIX VICINITY MAP PAGE A RATIONAL CALCULATIONS, CURB CUT, UDINLET, UDSEWER B STORM DRAIN SIZING, & RIPRAP CALCULATIONS DRAINAGE & EROSION CONTROL PLAN DRAWING & EROSION C CONTROL CALCULATIONS TABLE OF CONTENTS PAGE I. GENERAL LOCATION AND DESCRIPTION A. LOCATION 5 B. DESCRIPTION OF PROPERTY 5 II. DRAINAGE BASINS A. MAJOR BASIN DESCRIPTION 5 B. SUB -BASIN DESCRIPTION 5 III. DRAINAGE DESIGN CRITERIA 6 A. REGULATIONS 6 B. DEVELOPMENT CRITERIA REFERENCE AND CONSTRAINTS 6 C. HYDROLOGICAL CRITERIA 6 D. HYDRAULIC CRITERIA 6 N. DRAINAGE FACILITY DESIGN 6 A. GENERAL CONCEPT 6 B. SPECIFIC DETAILS 7 V. STORM WATER QUALITY 9 A. GENERAL CONCEPT 9 B. SPECIFIC DETAILS 9 VI. EROSION CONTROL 10 A. GENERAL CONCEPT B. SPECIFIC DETAILS 10 VII. CONCLUSIONS 11 A. COMPLIANCE WITH STANDARDS 11 B. DRAINAGE CONCEPT 11 C. STORM WATER QUALITY 11 D. EROSION CONTROL CONCEPT 11 REFERENCES 12 APPENDICES 13 Stautec Consulting Inc 209 South Meldrum Street Fort Collins CO 80521-2603 Tel: (970) 482-5922 Fax: (970) 482-6368 stantec.conn Ire $ta11eC Mr. Basil Harridan City of Fort Collins Water Utilities --Storm water 700 Wood Street Fort Collins, Colorado 80521 August 2, 2006 RE: Final Drainage and Erosion Control Report for Poudre Valley Health Systems Harmony Campus 4th Filing, Redstone Professional Office Building. Dear Basil: We are pleased to submit to you, for your review and approval, this Final Drainage and Erosion Control Report for Poudre Valley Health Systems Harmony Campus 46' Filing, Redstone POB. All computations within this report have been completed in compliance with the City of Fort Collins Storm Drainage Design Criteria, and adhere to the Final Drainage and Erosion Control Report for the Poudre Valley Health Systems Harmony Campus Infrastructure Project Development Plan, Fort Collins, Colorado, May 12, 2004. We appreciate your time and consideration in reviewing this submittal. Please call if you have any questions. Respectfully, Stantec Prepared by: John Gooch, EIT Jim Allen -Morley, P.E. Project Engineer Project Manager Final Drainage and Erosion Control Report StantK Poudre Valley Health Systems Harmony Campus Redstone Professional Office Building Fort Collins, Colorado August 2, 2006 w k,� Final Drainage and Er Poudre Valley H Harmony Campt Redstone Profes�iutia, Building Stantec