Loading...
HomeMy WebLinkAboutSite Certifications - 08/16/2000August 9, 2000 Mr. Jay Barber City of Fort Collins -Stormwater Utilities P .O. Box 580 Fort Collins, Colorado 80522 RE: Preston Center Second Filing -Country Ranch Certification of Storm Drainage Facilities JR Project 9194.02 Dear Jay : ~ JR ENGINEERING A Sub si diary of Westri an JR Engineering (JR) surveyed the existing storm drainage facilities for Preston Center Second Filing (Country Ranch) on May 8 and August 3, 2000. As a result of this effort , we offer the following for your review and approval : 1. Pipe C , the eastern-most of the two storm drain pipes from the parking lot to the concrete pan, was constructed in general conformance with the approved plans. Note: Under an approved plan revision, Pipe A was replaced with a sidewalk chase adjacent to Corbett Drive. 2. Pipe B, the western-most storm drain pipe, was constructed with the same invert elevation at both ends of the lower segment of pipe. The upper segment of Pipe B was constructed in general conformance with the approved plans . JR checked the elevation of the hydraulic grade line (HGL) for the lower segment of Pipe B, which would be flowing under pressure, to evaluate whether this flat lower segment could back up storm water into the parking lot. The attached calculations show that the elevation of the hydraulic grade line at the inlet is approximately one foot below the rim of the inlet. Therefore, although the constructed slope of the lower segment of Pipe B does not conform to the design slope, the resulting hydraulic condition still allows adequate storm drainage . .3. The detention facility located south of Timberwood Drive and west of County Road 9 has adequate volume and was constructed in general conformance with the approved plans. Computations are attached to verify the volume of storage provided . 4 . The concrete pan draining along the southern edge of the property to the detention facility was constructed in genera,l conformance with minimum City standards. The minimum record slope was calculated to be 0.34 percent, compared to a minimum design slope of 0.4 percent. 2620 East Prospea Ro ad , Sui te 190, Fo re Co lli ns, CO 80525 9i'0-49 l -9888 • Fax: 970-49 1-9984 • www.jrengi neeri ng.co m X:\9177 . I 2\corre s\080800 _JayBarber.doc Jay Barber August 9, 2000 Page 2 of2 This letter certifies that the items listed above are in general conformance with the approved plans , except as noted. Attached for your review are plan revision sheets with bolded elevations depicting the field-verified data. If you should have any questions or comments , please contact me at 491-9888. Thank you for your assistance on these issues. Sincerely, (e4P~ Kent Bruxvoort, P .E. Project Manager cc : Mr. JeffHiser -Brisben Development X :\9 177 . I 2\corre s\080 800 _Jay Barber.doc LOCATION: PROJECTNO : POND 305 -COUNTRY RANCH As-Built Detention Pond -Stage/Storage COUNTRY RANCH 9194 .00 COMPUTATIONS BY : SLT SUBMITTED BY : DATE : JR ENGINEERING 8/7/00 V = 1/3 d (A+ B + sqrt(A*B)) where V = volume between contours, ft 3 d = depth between contours, ft A = surface area of contour POND 305, RECORD VOLUME,8/7/00 1913.86 0 4914 18 .82 0.43 0.43 4915 5891 0.05 0.48 4916 7627 0.15 0.63 4917 8993 0.19 0.83 4918 10557 0.22 1.05 4919 12394 0 .26 1.31 4919.9 14296 0.28 1.59 4920 11462 0.03 1.62 4921 16697 0.32 1.94 4922 19590 0.42 2.35 Required Storage 10-yr = 1.22 ac-ft 100-yr = 2.03 ac-ft Provided Storage 10-yr = 1.59 ac-ft 100-yr = 2.35 ac-ft X:\911603\POND _ VOLUMES. X: \3910000 .a11\3919402\Drawings\PONO AS BUILT 8-7-00 .dwg Wed Aug 09 15: 11: 49 2000 I ' ' I ) / I I I I I vvvv ------11- 1 - I -------__, --------------\ I c:::- \ \ \ ~ \ ~ ) \ ) I I I I I I I I I I I I I I I I I \ '\_ - \ __ c;__~Y O L n~ _,,, ----===---==------=--==-=----- -= --=-- ---"'-I t) I ) I '\_ -- -/--• -.---­I <::[7/0i>3~ :: q3rodo)'d := ---- 0~ :: / H.L'tl0J'I t \ FINAL DRAINAGE AND EROSION CONTROL STUDY PRESTON CENTER SECOND FILING COUNTRY RANCH Prepared for: W. 0 . Brisben Companies, Inc. 4891 Independence Street, Suite 200 Wheat Ridge, Colorado 80233 (303) 299-9310 Prepared by: JR ENGINEERING, LTD. 2620 E. Prospect Rd., Suite . 190 Fort Collins, Colorado 80525 (970) 491-9888 May 11, 1998 Revised August 26, 1998 Revised November 17, 1998 Revised January 19, 1999 Job Number9194 .00 Pond 305 Proposed Detention Pond -Stage/Storage LOCATION : PROJECT NO: COMPUTATIONS BY : SUBMITTED BY : DATE : BRISB E N HOMES 9194 .00 J .ZUNG JR ENGINEERING, LTD . 1/19/99 V = 1/3 d (A+ B + sqrt(A*B)) where V = volume between contours, ft 3 d = depth between contours, ft pondinv 10-yr WSEL- 100-yr WSEL­ spill elev - top of berm - Pond 305* Stage (ft) 4914.08 4915 4916 4917 4918 4919 4919.9 4920 4921 4921.9 4922 4922.1 4922.5 4923 4924 A = surface area of contour Surface Incremental Area Storage (ft2) (ac-ft) 1820 0.00 5567 0.07 7273 0.15 9499 0.19 11195 0.24 12959 0.28 14701 0.29 14895 0.03 16903 0.36 18923 0.37 19148 0.04 19421 0.04 20514 0.18 21879 0.24 35172 0.65 *reflects new grading as of 1/99 9194pnd305b .xls Total Storage (ac-ft) 0.00 0.08 0.23 0.42 0.66 0.93 1.22 1.25 1.62 1.99 2.03 2.07 2.26 2 .50 3.15 DP 2 P-1 J-1 P-2 Outlet Proje,ct Title : BRISBEN Project Engineer: JR ENGINEERING, LTD . x :\39 '1 OO00 .all\3919400\drainage\dp2-ab .stm JR Engineering Ltd StormCAD v1 .5 (158) 08/09/00 11 :07 :57 AM C Haestad Methods , Inc. 37 Brookside Road Waterbury, CT 06708 USA (203) 755-1666 Page 1 of 1 PIPE SUMMARY TABLE Pipe Length Section Section Constructed Discharge Capacity Upstream Upstream Upstream Downstream Downstream Downstream Average (ft) Size Material Slope (cfs) (cfs) Invert Ground HGL Invert Ground HGL Velocity (ft/ft) Elevation Elevation (ft) Elevation Elevation (ft) (ftls) (ft) (ft) (ft) (ft) P-1 47 .88 19x30 inch Concrete 0 .013993 19.70 29 .73 25 .61 28.49 27 .24 24.94 29 .09 26.95 5 .97 P-2 65 .50 19x30 inch Concrete 0 .000000 19.70 0 .00 24 .94 29 .09 26 .81 24.94 28 .00 26.24 6.41 Project Title : BRISBEN Project Engineer : JR ENGINEERING , LTD . JR Engineering Ltd x:\391 0000 .all\3919400\drainage\dp2-ab .stm 08/09/00 11 :07 :35 AM © Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA (203) 755-1666 StormCAD v1 .5 [158) Page 1 of 1