The URL can be used to link to this page

Home My WebLink AboutPVH HEALTH SYSTEMS, HARMONY CAMPUS - ODP - 32-98 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTi f i i cc a i ( v } C cc a� cr <_ J V W Q. IL z s a o� uNno� o Q 0 � W = E� 0 0 w O F � a Y c � s c c ■ �= u 1L �O adoa 3►vna eWil O j e ovoaiiva ¢ �i�i�vd ! e NOIN� 4 a a O 4�nq L Ntw JMA L: L a } 3nN3Ab' l,b'W31 1 VICIP I REFERENCES 1. Storm Drainage Design Criteria and Construction Standards by the City of Fort Collins, Colorado, May 1984. 2. Erosion Control Reference Manual for Construction Sites by the City of Fort Collins, Colorado, January 1991. 3. McClellands Basin 100-Year Master Plan Update, Fort Collins, Colorado, by RBD, Inc., 1996. 4. Final Drainage and Erosion Control Study for Timber Creek, P.U.D., First Filing, Fort Collins, Colorado, by RBD, Inc., July 1994. 5 VI. EROSION CONTROL A. General Concept Erosion control plans and calculations for the Poudre Valley Hospital will be applied as the site is developed. 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. B. Drainage Concept The proposed drainage concepts presented in this study and shown on the overall drainage plan adequately provide for the transmission of developed on -site runoff to the proposed detention ponds. C. Storm Water Ouality Preceding development, Best Management Practices will be determined for the treatment of storm water runoff. D. Erosion Control Concept Preceding development, erosion control plans will be produced in accordance to the recommendations provided for in the City of Fort Collins Storm Drainage Design Criteria Manual. 4 IV. DRAINAGE FACILITY DESIGN A. General Concept Flows from the Poudre Valley Hospital site will travel through a system of curb and gutters, storm drain pipes, concrete pans and swales to reach the two permanent detention ponds. Once the flow reaches the ponds, it will be released using a staged release rate. Flow from Pond 1 will travel through storm drain pipe to release into Pond 2. The flow from Pond 2 will release into the concrete ditch, conveyance element 39, from an outlet structure. The rational method was used in determining the size of the two permanent detention ponds. The Master Plan for the McClellands Basin requires on -site detention using a staged release rate of 0.20 cfs/acre for a 10-year design storm and 0.50 cfs/acre for a 100 year design storm. Calculations used for the Overall Drainage Plan can be found in the Appendix. The site has been broken into two basins, 1 and 2. Basin 1 contains 75.98 acres, a majority of the site. Runoff generally will flow in a southeasterly direction to a regional detention pond in the southeastern corner of the site. The remainder of the site is Basin 2 and consists of 23.56 acres. Its runoff will flow in a southeasterly direction to a detention pond located in the northeast quadrant of the site. The two permanent detention ponds to be constructed on the site will be responsible for runoff for the entire site. The two ponds will discharge into Conveyance Element 39, a concrete ditch at the southern property line which ultimately drains to the McClellands Basin Drainageway at the allowable release rate for the 10-year storm event of 19.90 cfs combined and for the 100-year storm event of 49.97 cfs. V. STORM WATER QUALITY A. General Concept The State of Colorado requires Stormwater Management Plans as part of their permit process. The Poudre Valley Hospital will use various Best Management Practices for the treatment of storm water runoff that will be implemented in the construction phase of the project. These BMP's and their related calculations will be applied as the site is developed. 3 into Conveyance Element 39, a triangular concrete ditch that runs 2,160 feet along the southern property line. Excerpts from the McClellands Basin 100-Year Master Plan Update can be found in the appendix of this report. The flow ultimately discharges into the McClellands Basin Drainageway. No off -site runoff from properties surrounding the Poudre Valley Hospital site pass through the site. With the construction of the site, no additional flows are anticipated. 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 April 1, 1996 are being utilized in this Overall Drainage Study. The Poudre Valley Hospital site is currently being utilized as agricultural land, and the McClellands Basin Master Plan for the site does not include on -site detention facilities for the future development. C. Hydrologic Criteria The SWMM hydrologic model was previously used in the McClellands Basin Master Drainage Plan. The Poudre Valley Hospital Drainage Report will utilize the McClellands Basin Master Drainage Plan SWMM model and simply expand on it. The SWMM model will be updated in the future. D. Hydraulic Criteria All calculations within this study have been prepared in accordance with the City of Fort Collins Storm Drainage Criteria and are included in the appendix. E. Variances from Criteria No variances from the City of Fort Collins Storm Drainage Criteria are being sought for this project. Pa OVERALL DRAINAGE REPORT FOR THE POUDRE VALLEY HOSPITAL HARMONY CAMPUS FORT COLLINS, COLORADO I. GENERAL LOCATION AND DESCRIPTION A. Location The Poudre Valley Hospital 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 the Appendix. 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 Poudre Valley Hospital site contains approximately 99 acres of land, all of which is currently undeveloped and being proposed for the Harmony Campus of Poudre Valley Hospital. The majority of the property currently consists of cultivated farmland. The site generally slopes in a southeasterly direction at approximately 2.0%. There is a concrete irrigation ditch along the northern property line of this site called the Spring Canyon Lateral, owned by the Warren Lake Company. This ditch is to be relocated and will remain active. II. DRAINAGE BASINS A. Major Basin Description The Poudre Valley Hospital site lies entirely within the McClellands Basin. This drainage area is specifically described in the report entitled McClellands Basin Master Drainage Plan, prepared by Greenhorn and O'Mara, Inc, 1986. This update shows the Poudre Valley Hospital site to be located in portions of Basins 215, 216, and 222. In the Final Drainage and Erosion Control Study done for Timber Creek P.U.D., completed by RBD, Inc., 1994, the SWMM Model was updated. In the update, the Poudre Valley Hospital is located in Basin 316. Applicable portions of these studies are included in the Appendix. Historic drainage patterns on the subject site are in a southeasterly direction per the McClellands Basin 100-Year Master Plan Update. The site historically discharges 1 APPENDIX PAGE VICINITY MAP 1 HYDROLOGY 3 DETENTION POND SIZING 9 TABLES AND FIGURES 15 EXCERPTS FROM McCLELLANDS BASIN MASTER DRAINAGE PLAN 19 EXCERPTS FROM PREVIOUS DRAINAGE REPORTS 25 SWMM MODELS 33 TABLE OF CONTENTS PAGE I. GENERAL LOCATION AND DESCRIPTION A. LOCATION 1 B. DESCRIPTION OF PROPERTY 1 II. DRAINAGE BASINS A. MAJOR BASIN DESCRIPTION 1 III. DRAINAGE DESIGN CRITERIA A.. REGULATIONS 2 B. DEVELOPMENT CRITERIA REFERENCE AND CONSTRAINTS 2 C. HYDROLOGICAL CRITERIA 2 D. HYDRAULIC CRITERIA 2 E. VARIANCES FROM CRITERIA 3 IV. DRAINAGE FACILITY DESIGN A. GENERAL CONCEPT 3 V. STORM WATER QUALITY A. GENERAL CONCEPT 3 VI. EROSION CONTROL A. GENERAL CONCEPT 4 VII. CONCLUSIONS A. COMPLIANCE WITH STANDARDS 4 B. DRAINAGE CONCEPT 4 C. STORM WATER QUALITY 4 D. EROSION CONTROL CONCEPT 4 REFERENCES 5 THE SEAR -BROWN GROUP FULLrSERVICE DESIGN PROFESSIONALS FORMERLY RBD, INC. 209 SOUTH MELDRUM FORT COLLINS. COLORADO 80521-2603 970-482-5922 FAX:970-482-6368 July 22, 1998 ' Mr. Basil Hamdan City of Fort Collins ' Water Utilities--Stormwater 235 Mathews Street Fort Collins, Colorado 80522 ' RE: Overall Drainage Report for the Poudre Valley Hospital - Harmony Campus Dear Basil: We are pleased to submit to you, for your review and approval, this Overall Drainage Report for the Poudre Valley Hospital - Harmony Campus. All computations within this report have been completed in compliance with the City of Fort Collins Storm Drainage Design Criteria. The Preliminary Drainage and Erosion Control Report for the PDP is being submitted simultaneously. We appreciate your time and consideration in reviewing this submittal. Please call if you have any questions. Respectfully, The Sear -Brown Group Prepared by: Storm Gewirtz, E.I.T. Project Engineer Traci Downs, E.I.T. Project Engineer i cc: File 823-001 Albert Kahn Associates Reviewed by: Kevin Gingery, P.E. Engineering Manager I ' NEW YORK•PENNSYLVANIA COLORADO•UTAH STANDARDS IN EXCELLENCE EQUAL OPPORTUNITY EMPLOYER Overall Drainage Report Poudre Valley Hospital Harmony Campus, Fort Collins, Colorado July 1998 THE SEAR -BROWN GROUP Standards in Excellence