The URL can be used to link to this page

Home My WebLink AboutCOLLINDALE GOLF COURSE CLUBHOUSE - PDP - 17-01A - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTPROJECT W Q LOCATION } W Q W � J W .Pq H❑RSET❑❑TH R❑AD C❑LLINDALE G❑LF C❑URSE Li WARREN a LAKE �Q J VICINITY MAP N TS -7 5.0 APPENDIX Collindale Golf Course Drainage Study June 12, 2001 S. A. Miro Proj. No. 01068 Page 6 3.4 EROSION CONTROL ■ During construction the majority of the developed site area will be sloped towards the east at slopes in the range of 1 % to 2%. Staked hay bales will be placed in the proposed trickle pan area in the parking lot to trap sediment before entering the lawn area. Silt fence surrounding downslope area of the proposed construction will trap additional sediment. Grading will be mulched within 30 days of reaching finished grade. After construction, a proposed pad of modular block porous pavement downstream of the proposed 6' curb cut will provide some settlement of particles and provide an easier means of cleaning trash and sediment from the lawn area. These erosion control measures will minimize erosion and sedimentation damages during and after the period of construction for the proposed Collindale Golf Course clubhouse and parking lot. 4.0 CONCLUSIONS AND RECOMMENDATIONS As it exists today, the golf course's natural terrain provides a means for controlling storm runoff. Horsetooth Road, which borders the course, sits higher than the golf course as does the Union Pacific Railroad at the downstream end of the drainage area creating a natural depression storage volume. No signs of erosion exists that would show excessive velocities are present and an additional 0.13 acres of impervious coverage will not adversely affect current conditions. The construction to take place will provide means of erosion control. In conclusion, the proposed Collindale Golf Course site will have drainage characteristics closely resembling existing conditions that already are reasonable. Collindale Golf Course Drainage Study June 12, 2001 S. A. Miro Proj. No. 01068 Page 5 1 3.0 DRAINAGE ANALYSIS 1 1 3.1 EXISTING CONDITIONS tThe site currently is an active golf course with a clubhouse along with an associated parking lot. Slopes in the parking lot vary between 0.50% and 2.00%. The general ' drainage pattern flows eastward to a curb cut in the parking lot and. The existing 10- year flow at this point is 5.41 cfs and the 100-year flow is 13.80 cfs. Storm water then proceeds to flow easterly to the Union Pacific Rail line at a peak value of 7.03 cfs in the 10-year event and 17.91 cfs in the 100-year event. 3.2 PROPOSED CONDITIONS The proposed construction increases the impervious coverage by approximately 0.13 acres more than existing. This results in an increase in the parking lot area of 1.56 cfs during the 10-year storm and 4.00 cfs during the 100-year storm. A raised concrete hump is located along the driveway in front of the proposed clubhouse. During the 10- I year storm, 5.2 cfs will flow around the hump along the gutter. Calculations using Land Development DesktopTM channel calculator program shows that the gutter along the hump has capacity for 6.11 cfs before overtopping. During the 100-year storm, 13.1 cfs ' will overtop the raised concrete approximately 3.5 inches to an elevation of 4971.5 which is 5.5 feet below the first floor. Runoff from the 2.2 acre parking lot drainage area will discharge through a proposed 6' curb cut at 6.97 cfs in the 10-year storm to the ' same general area it does under existing conditions. The water then flows approximately 1,800 feet eastward over lawn area to the railroad at shallow slopes. The drainage area to the railroad is 22.5 acres and peaks at a 41.9 cfs rate during the 100- Iyear storm. 3.3 RETENTION POND There is no proposed detention system designed for the site. As mentioned above, the runoff will flow eastward to the railroad. Lowpoints in this area will provide retention for any storm water reaching this point which does not infiltrate into the ground beforehand. A mass balance detention sizing analysis was performed for this study. Using a conservative historical rate, assuming the entire drainage area is undeveloped with no impervious coverage or ponding, determines that a detention volume of 1.5 acre-feet is necessary. The amount of retention needed is equal to twice the detention volume, or 3 acre-feet. Using Land Development DesktopTM terrain modeling software, a retention volume of 4.4 acre-feet exists near the railroad which will satisfy requirements. Since retention is taking place and there is 1800 feet of sheet flow in the golf course grass, no additional means of water quality is proposed. Collindale Golf Course Drainage Study June 12, 2001 S. A. Miro Proj. No. 01068 Page 4 2.4 RUNOFF COEFFICIENTS The runoff coefficient, C, used in conjunction with the Rational Method, is listed in the Appendix, and was obtained from Table 3-3 of the "City of Fort Collins Storm Drainage Design Criteria and Construction Standards." The Rational Method Formula used in this report is: Q=CCfIA Where Q = Storm Flow, CFS I = Rainfall Intensity (in/hr) A = Drainage Area (Acres) C = Runoff Coefficient Cf = Frequency Adjustment Factor 2.5 TIME OF CONCENTRATION The time of concentration (when maximum discharge of the drainage area is reached) is the time required for runoff from the most remote point of the drainage area to arrive at the design point. The "most remote point' is that point from which the time of flow to the design point is the greatest and not necessarily the greatest linear distance. G I J 7 2.0 DESIGN CRITERIA 2.1 GENERAL The procedures, criteria and standards for stormwater management in this design comply with the reference manual "City of Fort Collins Storm Drainage Design Criteria and Construction Standards" and also "Urban Storm Drainage Criteria Manual' volumes 2 and 3. Technical data as it applies to this analysis is included in the Appendix. 2.2 ANALYSIS Since the study area is less than 200 acres, an analysis and determination of the amount of flows at various predetermined points has been made using the "Rational Method." The runoff analysis is based on the proposed land use and topographic features of the project area. The average land slopes are used for computing runoff. 2.3 DESIGN STORM FREQUENCIES The initial and major design storm runoff drainage has been analyzed in this report. The initial design storm drainage system, based on a 10-year storm frequency, is ! designed to provide protection against regularly recurring damage, provide an orderly r drainage system and offer convenience to the general public. The storm sewer system and is considered to be part of the initial storm drainage system. The major design storm drainage system, based on a 100-year storm frequency, is that system which will convey the major storm runoff that will cause little or no major property damage or loss t of life. Collindale Golf Course Drainage Study June 12, 2001 S. A. Miro Proj. No. 01068 Page 2 1.0 INTRODUCTION 1.1 PURPOSE The purpose of this report is to present the drainage characteristics for the proposed reconstruction of the clubhouse and parking lot at the Collindale Golf Course in the City of Fort Collins. 1.2 SITE LOCATION The proposed construction is located at 1441 East Horsetooth Road along the south side of Horsetooth Road in between Lemay Avenue and Timberline Road. This would place the site in the Northwest quarter of Section 31, Township 7 North, Range 68 West of the 61h P.M. , City of Fort Collins, Larimer County, Colorado. The Appendix contains a Location Map. Development of the site will entail the demolition of the existing clubhouse and parking lot and the constructing of a new clubhouse and parking lot. Collindale Golf Course Drainage Study June 12, 2001 S. A. Miro Proj. No. 01068 Page 1 TABLE OF CONTENTS 1.0 INTRODUCTION.......................................................................................................1 1.1 PURPOSE 1 1.2 SITE LOCATION 1 2.0 DESIGN CRITERIA..................................................................................................2 2.1 GENERAL 2 2.2 ANALYSIS 2 2.3 DESIGN STORM FREQUENCIES 2 2.4 RUNOFF COEFFICIENTS 3 2.5 TIME OF CONCENTRATION 3 3.0 DRAINAGE ANALYSIS............................................................................................ 4 3.1 EXISTING CONDITIONS 4 3.2 PROPOSED CONDITIONS 4 3.2 WATER QUALITY POND 4 3.3 RETENTION POND 4 3.4 EROSION CONTROL 5 4.0 CONCLUSIONS AND RECOMMENDATIONS......................................................... 5 5.0 APPENDIX ................................................................................................................ 6 LOCATION MAP 7 HYDROLOGY 8-15 6' CURB CUT CALCULATION 16-17 RAISED CONCRETE HUMP CALCULATIONS 18-20 RETENTION STORAGE CALCULATIONS 21-23 EROSION CONTROL CALCULATIONS 24-25 DRAINGE AND EROSION CONTROL PLAN DRAINAGE BASIN MAP No Text