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Home My WebLink AboutRIVERSIDE COMMERCIAL - PDP/FDP - 9-07/A - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTOACNS �q P NIX NATURE AREA r VOR NeRN CATTAIL CHORUS NATURE AREA E. PIT�IN ST PROSPECT RD EDORA PARK W I,J STUART ST 11 w F/ IN SHEET 1 OF , DATE: 4/16/07 1640 RIVERSIDE DRIVE % North Star design, inc. scA E: =,000' (RIVERSIDE STORAGE) 700 Automaton Drive, Unit I Windsor, Colorado 80550 APPENDIX A VICINITY MAP _.............. 6, CONCLUSIONS 6.1 Compliance with Standards e in liance 1 computations that have been the completed within thisn al foort r Construcption Sites", the Al p "City of Fort Collins Erosion Control Reference Ma the « Fort Collins Storm Drainage Design Criteria Manual", asnnoted in Sec ion 4 City of Drainage Criteria Manual" except where variances are requested of this report. 6.2 Drainage Concept resented in this report and on the construction plans The proposed drainage concepts p runoff adequately provide for the collection and conveyanee de a ned runoff downstreamentron area. Conveyance elements exist to adequately convey groundwater is encountered, a Colorado Department of If, at the time of construction,elt would be required. ction Dewaterino Health Construg REFERENCES 1. City of For t Collins, "Storm Drainage Criteria Manual", (SDCM), dated March, 1986. aa ge and Flood Control District, "Urban Storm Drail Urban Draina Qe Criten, 2. Manual", Volumes 1 and 2, dated March, 1969, and Volume 3 dated September 1992. W ention and and outlet hidina the et s project, iric 0 All drainage facilities proposed with ealand maintained by the prop structure are private and wierty owner or Owner's ll be own Association. 5, EROSION CONTROL 5.1 General Concept movement from the site and into adjacent This site lies within the Moderate Rainfall and Wind Erodibility Zone per the City of Fort s The potential exists for silt streets, which could Collins Zone Maps. o f mud onto existing properties. Potential also exists for tracking required performance standard for the site is then wash into existing storm systems. The 0 o construction and after paving, this figure has been exceeded with the use 79.9 /o. During and as a sediment basin. The calculated of silt fence and by using the detention p ite, using the standard City performance standard for the sof Fort Collins Effectiveness Calculations, is 87.3%• ount for the entire site is $6,675 (see Appendix D)• The erosion control escrow am 5.2 Specific Details ' it the amount of silt leaving the site, several erosion control measures shall be To limit appropriate and the site implemented during construction. Wattles will be used tracking pad shalle installed at the Q tracked onto the existing pavement. boundaries shall have silt fence installed. A vehicle tracicrng p site entrance in order to control the mud being hall be kept In grading, disturbed areas s During overlot oroughened condition pond will be used as asedim n watered to reduce wind erosion. The proposed detention basin during the construction process. 4 3.4 Hydraulic Criteria Hydraulic elements have been designed per City of Fort Collins standards to adequately convey the 100-year storm runoff from this site to the proposed detention pond. A proposed outfall pipe and an existing drainage swale will convey the detained runoff from the site to the downstream railroad crossing. 4. DRAINAGE FACILITY DESIGN 4.1 General Concept On -site runoff will be conveyed to the detention pond via surface flows in concrete pans and curb and gutter. The detained runoff will discharge into the existing charnel located at the northeast comer of the site. From there, runoff will be conveyed in the existing swale downstream to an existing railroad crossing. 4.2 Specific Flow Routing With this design, the site is modeled as a single basin. Drainage design for this site has been designed to convey on -site runoff to the proposed detention pond with as little future will be conveyed to the detention pond via maintenance as possible. On -site runoff surface flow in concrete pans and curb & gutter. The detention pond will release the detained runoff from the site at the existing 2-year runoff rate. The developed 2-year runoff rate for this site is 7.2 cfs; the developed 100-year runoff rate is 21.5 cfs. Two variances are requested for this project. A variance is being requested to reduce the minimum freeboard for the detention pond from 1.0' to 0.5'. A variance is also being requested to allow the extended water quality volume to be included in the detention volume storage for the 100-year storm. 4.3 Drainage Summary This site has been designed to meet or exceed the "City of Fort Collins Storm Drainage Design Criteria Manual" specifications except where variances are requested as noted in Section 4.2 of this report. The proposed drainage design for t isstsit maintenhas ee signed to ijr convey on -site runoff to the detention pond while minimiz� 3 to the north along the rear of the adjacent properties to an existing pipe under the railroad tracks. The existing Swale across the adjacent properties concept determined Poris to to a historic conveyance for this site. With the proposed existing drainage runoff will continue to be released into the existing Swale via a short outfall pipe. 3, DRAINAGE DESIGN CRITERIA 3.1 Regulations the ainaae This report was prepared to meet or exceed where City variances are rlequested aStorm s not d in Design Criteria Manual" specifications except Section 4.2 of this report. Where applicable, the criteria established in the "Urban Storm Drainage Criteria Manual" (UDFCD), 2001, developed by the Denver Regional Council of Governments, has been used. 3.2 Development Criteria Reference and Constraints requireme ts The runoff from this site has been routed to conform torr to the detention of extended Fort Collins Stormwater Department. Both storm water quality detention are required for this site and are being provided by the proposed on -site detention pond. The release rate from the site will be equal to the existing 2-year runoff. 3.3 Hydrologic Criteria aced for the 2-year minor and 100-year major storm Runoff computations were prepared the frequencies utilizing the rational method. Aeprtl o. StandardlFolrm8 (SF associated8) provides h me basins are included in Appendix B of this report. of concentration calculations for all sub -basins. Detention volume was calculated using the runoff rate for the 2-yer sections of asphalt pavinand rainfall event gravel. existing site conditions, which includes existing s The FAA method for detention pond sizing was utilized to determine the required volume. Water quality volume was calculated using the method recommended in the "Urban Storm Drainage Criteria Manual'. Refer to the detention calculations included in Appendix C of this report. 2 1, GENERAL LOCATION AND DESCRIPTION 1.1 Location Range 68 West of the Sixth Principal This site is located on the east side of Riverside Drive an rth of East Prospect Road in the T Township 7 North, R Ma in Southeast Quarter of Section 18, Colorado. See the Vicinity P Meridian, in the City of Fort Collins, Larimer County, Appendix A of this report. existing existing storage units, on the east by This project is bounded on the north by Riverside Drive, and on the south by Union Pacific Railroad tracks, on the west by existing Rivendell School. 1.2 Description of Property e is ly The entire project consists of approximately 2.2 acres. e hs totthe northeatst with slopes with areas of existing asphalt and gravel. Existing slop ranging from approximately L5% to 3%. The site currently drains into an existing Swale located at the northeast corner of the site. five self -storage Proposed development on -site will arng drainage patterns will not include two office buildings, buildings, and associated drives, parking, walks. Exist i be significantly altered with this development. 2 DRAINAGE BASINS AND SUB -BASINS 2.1 Major Basin Description got ro osed development lies within the Spring Creek Drainage Basin. Thep p p quality detention are required in this basin. T Spring stormwater detention and extended water q City requirement for stormwater detention in the Sp gsingle-staf � ear runoff. Creek basin is a detention with a 100-year release rate equal to the existino --Y 2.2 Sub -basin Description Runoff from this site currently flows to an existing Swale located in the northeast cor of the site. From there, the runoff is conveyed in a proposed pipe and the existing sv 1 l0 TABLE OF CONTENTS TABLE OF CONTENTS ............................. .................................................... LOCATION AND DESCRIPTION 1 GENERAL....................... 1.1 Location ........................... of Property ............................. :.. 1.2 Description AGE BASINS AND SUB -BASINS ..............................1 DRAIN...............2 2.1 Major Basin Description .............................................. 2.2 Sub -Basin Description DESIGN CRITERIA....................................................2 3 DRAINAGE ..................... Criteria Reference and Constraints ............................................•••• 3.1 Regulations .................. 3 3 2 Development Hydrologic Criteria............................................................................................... 3.3 3.4 Hydraulic Criteria ...................... DRAINAGE FACILITY DESIGN 4 General Concept...................................................................................................... 4 4.1...................................................................... . g ...........:.............................................._ 4.2 Specific Flow Routing 4.3 Drainage Summary ............................................... 6 EROSION CONTROL ...............................• ...6 5 ..................... 5.1 General Concept .......................... 5.2 Specific Details ................................................... with Standards....................................................................................7 CONCLUSIONS 6' 6.1 Compliance .......................................... fiance 6.2 Drainage Concept ................................ ............................ .8 .................................... 7. REFERENCES ........................ P,ppENDICES A Vicinity Map Computations B Hydrologic Comp Pond Sizing Calculations C Detention Erosion Control Calculations D E Figures and Tables Excerpts from Previous Reports F iii North Star ® design, inc. May'), 2007 Glen Schlueter City of Fort Collins Stormwater 700 Wood Street Fort Collins, CO 80522-0580 RE: Final Drainage and Erosion Control Report for 1640 Riverside Drive (Riverside Storage) Dear Glen, I am pleased to submit for your review and approval, this Final Drainage and Erosion Control Report for 1640 Riverside Drive. 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. o�`NQ „RECi Sincerely, O G P KRO0. T�9 :¢ n: 0 Cr 31306 •4u ii -7r,r, A. o-n, ntinn nrive. Unit I Windsor, Colorado 80550 FINAL DRAINAGE AND EROSION CONTROL REPORT FOR 1640 RIVEDT o E E (,,VERSE S prepared for: Wickham Gustafson Architects 1449 Riverside Avenue Fort Collins, CO 80524 prepared by: North Star Design nit I 700 Automation Drive, Windsor, Colorado680550 (970) May 3, 2007 Job Number 264-02