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Home My WebLink AboutSite Certifications - 05/30/2007N May 17, 2007 Mr. Jay Barber City of Fort Collins Storm Water Utility 700 Wood Street Fort Collins, CO 80521 MAY 17 2007 J•R ENGINEERING A Westrian Compa� �j, 0 Re: Detention Pond and Drainage Certification for First Community Bank Plaza JR Project 39468.00 d �aCoZ9� Dear Mr. Barber, The purpose of this letter is to serve as a Detention Pond and Drainage Certification for the First Community Bank Plaza. JR Engineering has reviewed the following items through field observations and a survey completed by our survey department: o Detention/Water Quality pond volumes o Water Quality Outlet Structures o Storm Pipe inverts o Flowline elevations o Erosion control measures Our survey department surveyed the detention/water quality ponds and respective outlet structures. The results of this survey indicate the South Pond has been constructed in accordance with the approved design. The North Pond was not constructed according to the approved plans due to a slight,revision of the curbline near the drive-thru area. As previously discussed with the City, the side slopes of the pond were modified to accommodate the required detention volume. Upon review of the pond as-builts it was determined that the North Pond will operate in general accordance with the approved design. Both ponds have adequate volumes and positive drainage. As-builts of The North Pond and the South Pond have been attached. It should be noted that the elevations for the North Pond and the South Pond might change subsequent to the date of the surveys due to natural and/or artificial actions, reseeding and landscaping. We expect these changes to be minimal. Enclosed with this letter you will find as -built stage -storage calculations for the North Pond and the South Pond. The required water quality capture volumes (WQCV) and 100-year detention volumes were obtained from the "Final Drainage and Erosion Control Report for first Communitv Bank Plaza" (JR Eng. April 2006), approved by Wes Lamarque. The water quality outlet structures are in general conformance with the approved plans. The water quality plate for the North Pond has the correct number and size of holes. The water quality plate for the South Pond also has the correct number and size of holes. The North Pond was found to have slightly less volume than proposed, but in our opinion is adequate at 0.17 acre-feet and would meet the proposed 0.22 acre-feet of detention with a slight reduction 2620 Fast Prospect Road, Suite 190, Fort Collins, CO 80525 970-491-9888 • Fax: 970-491-9984 • w Jrengineering.com 0/wn First Community Bank Plaza, May 17, 2007 Page 2 of 2 in freeboard. The as -built 100-year detention volume for the South Pond is maintained at 0.26 acre-feet at an elevation of 5023.0 with +/- 1' of freeboard. In all, it is anticipated that the North Pond and the South Pond are adequate and will perform as intended. JR Engineering has reviewed the permanent erosion control measures and it appears that riprap and trickle pans for the South Pond have been installed in general accordance with the design plans. The North pond did not have the proposed trickle pan constructed at the time of our site visit. It is anticipated that the trickle pan will be constructed and/or adequate erosion control will be installed in the North Pond. JR also observed that temporary erosion control measures such as silt fence and inlet protection were in place at the time of our field visit. The final landscaping was being planted during the time of the site visit. Our survey department preformed an as -built survey on the First Community Bank Plaza storm system and grading. In general, the flow line elevations, invert elevations and pipe slopes were built according to plan. Slight deviation from the plans were noted, but not expected to have a negative impact on the function of the storm system or site drainage. Based upon our field visits and survey information, it is our opinion that the drainage facilities as noted above for the First Community Bank Plaza have been constructed in general conformance to the approved plans. Sincerely, JR Engineering, LLC 000 LICt4rS, N Prepa By: Review '.� •Sp••• O �c 39848 m Justin Fecteau J sephargne, P,.:a�� Design Engineer roject §1 tj&I E�G� X:\3950000.all\3951500\Word\LettersWs-built Pond Cert.doc Proposed Detention Pond - Stage/Storage LOCATION: PROJECT NO: COMPUTATIONS BY DATE: North Pond SWMM 5 Pond SU2 Pond Invert rr1 orol 100-yr WSEL 1y:1:14*071:7f: PALMER JFK PLAZA 39468.00 es 3/24/2006 V = 1/3 d (A + B + sgrt(A*B)) where V = volume between contours, ft3 d = depth between contours, ft A = surface area of contour Stage (ft) Surface Area W) Incremental Storage (ac-ft) Total Storage (ac-ft) Detention Storage (ac-ft) 5014.55 0 5015.00 441 0.002 0.00 0.00 5016.00 1785 0.024 0.03 0.00 5017.00 2164 0.045 0.07 0.05 5018.00 2483 0.053 0.12 0.10 5019.00 2808 0.061 0.18 0.16 5019.84 3632 0.062 0.25 0.22 5020.00 3789 0.014 0.26 0.23 5021.00 3445 0.083 0.34 0.32 WQCV Provided = 0.03 ac-ft at 5016.00 Total Detention Volume Provided = 0.22 ac-ft at 5019.84 100-yr WSEL Required = 5019.84 Per SWMM 5.0 South Pond SWMM 5 Pond SU1 Pond Invert WQCV 100-yr WSEL FREEBOARD Stage (ft) Surface Area (W) Incremental Storage (ac-ft) Total Storage (ac-ft) Detention Storage (ac-ft) 5017.00 0 5018.00 1300 0.010 0.01 0.00 5019.00 1750 0.035 0.04 0.00 5019.01 1755 0.000 0.05 0.00 5020.00 2250 0.045 0.09 0.05 5021.00 2850 0.058 0.15 0.10 5022.00 3470 0.072 0.22 0.18 5023.00 4160 0.087 0.31 0.26 5024.00 4890 0.104 0.41 0.37 WQCV Provided = 0.05 ac-ft at 5019.01 Total Detention Volume Provided = 0.26 ac-ft at 5023.00 100-yr WSEL Required = 5023.00 Per SWMM 5.0 3946800wq and pond volumes.xls AS -BUILT Detention Pond - Stage/Storage LOCATION: PALMER JFK PLAZA PROJECT NO: 39468.00 COMPUTATIONS BY: JPF DATE: 5-09-2007 AS -BUILT INFO V = 113 d (A + B + sgrt(A*B)) where V = volume between contours, ft3 d = depth between contours, ft A = surface area of contour North Pond SWMM 5 Pond SU2 Pond Invert WQCV 100-yr WSEL FREEBOARD Stage (ft) Surface Area (ft) Incremental Storage (ac-ft) Total Storage (ac-ft) Detention Storage (ac-ft) 5014.65 0 5015.00 374 0.001 0.00 0.00 5016.00. 1178 0.017 0.02 0.00 5016.22 1355 1 0.006 0.03 0.00 5017.00 1605 0.026 0.06 0.03 5018.00 0.040 0.10 0.07 5019.00]3q072 0.048 0.15 0.12 5020.000.058 0.20 0.17 5020.700.047 5021.000.022 0.25 0.22 0.27 0.24 WQCV Provided = 0.03 ac-ft at 5016.22 Total Detention Volume Provided = 0.17 ac-ft at 5020.00 South Pond SWMM 5 Pond SU1 Pond Inver) WQCV 100-yr WSEL FREEBOARD Stage (ft) Surface Area (ft) Incremental Storage (ac-ft) Total Storage (ac-ft) Detention Storage (ac-ft) 5017.29 0 5018.00 869 0.005 0.00 0.00 5019.00 1801 0.030 0.03 0.00 5019.35 2015 0.015 0.05 0.00 5020.02 2411 0.033 0.08 0.03 5021.00 2875 0.061 0.14 0.09 5022.00 3342 0.071 0.21 0.16 5023.00 3839 0.082 0.30 0.26 5024.00 4430 0.095 0.39 0.35 WQCV Provided = Total Detention Volume Provided = 0.05 ac-ft at 5019.35 0.26 ac-ft at 5023.00 3946800wq and pond volumes.xls I I 'F'RlF-S� 1 \ 5p20�t'��tijFNri 'i�?a �t_ I }FtivFSF�ai . �? / 160 \. 1 p d AS -GMT 910T 1 5pry� , p2n .. l Sg11X POW AS•-BIILT OONIOIIRS - ' I r i ry � .r F\ %•' %s_ Q. m �o bra � o, i I 1 a rg o on s i �_ «-q m _. N.. ......... ..._ ........ P I \ I I vao w/ T ooMouLa ;. II I i o Da t •, v, o N ry i , , ; , .• i I �a9 k49i - .y 7i �p \\-�'vv Jr o,6 YLLI,J S oy I (Va _ / L JOHN F. KENNEDY PARKWAY I i, 40 20 0 40 SCALE: 1" = 40' NOTE: INFORMATION OTHER THAN THE AS —BUILT CONTOUR IS FROM THE APPROVED PLAN AND DOES NOT REPRESENT AS —BUILT INFORMATION DRAINAGE CERTIFICATION FIRST COMMUNITY BANK PLAZA 9515.00 5-10-2007 SHEET 1 OF 1 ---SEE SflEETSE(79i20)__�_____---_ L40OR COSY CxjJAL— • ago OUT a / r / / / / • NACF � -T---- }___ - 1I WssI /1// , 11711 01 r 1S1T FLOOR ` .I IlllllrELEY. E ,� oil Irllllp45.0e 11111' sW EAE 4. IIIIIt +W2A$ . "y s` r s d III ill III 1 L I \ \ \ , `�_.... VG 19, H1 \ \\i..: ,. \ IN YR X 1 ,/ \ � M.� \,� IWQ, <p• \ \ 1FR EtEv. ytV 1 -- ACCESS- _EARNFMT \ \ t4 \ —Ltt A _ _ \ - W Tw 2.0 ' \\ Imo— 20. E\ E \ 41�HN prNDD, I FGFNH EXISTNG PIPES hINLETS ----- EXCITING1' CONTOUR PC DRAW ELEVATION PROPOSED PIPE PROPOSED W CONTOUR FG FINISHED gDADE SW SIDEWALK PROPOSED EXISTING SPOT ELEVATOR LP LOW POINT HARED ENO SECTOR I �/W PROPOSED 1' CONTOUR UNLESS LABELiD OTUERMSE 1W_ wtoo PROPOSED SPOT ELEVAWON EC EDGE DF CONCRETE J V PROPOSED INIET ON OUTLET STRUCTURE MERTCK CURB W/ CATCH GUTTER FT FLOW UNE TIN TOP DF WALL Is PROPOSED INLET LOT " ` RETAINING WALL TC TOP OF TI TOP OF ISLAND I ��..... LIMITS OF CONSIRUC °JT• FILEiT FINISHED BOOR HP HIg1 PONTT BI BOTTOM OF ISLAND H — — — EXISTING 5' CONTOUR EK EXISTNG ONADE n ------------- p 0 <6ww pd3 W0FL za w F m too �ujY wo < ooao ff AIdIXR / FwQ_Q_ UZZo€ z 0_ 0 0 / / Io E .5° lt !A o aW GS FmV OIo ✓ o y��y••11 o o l Op'NZ^N I K pLLX�O I i I w Gjm an 8 ¢ E LL CIL zx 6 irSI LL OL i� 20 10 0 20 !D p g F SCALE 1' _ 20 z S 91 = DE NOTES!, a I. PIE RIP OF FOUNDATION ELEVATIONS SHOWN ARE THE MINIMUM A ELEVAPWS REWIRED FOR PROTECTION FROM THE 100-YEAR STORF IN- MINIMUM ORATE FINISHED IN STREETS. ELEVATION AHOVE THE 1W-YEAR WATER SURFAEE IN ACUMEAS I.LELB, DITWES, SWAIES. OR DINER DRAINAGE FAESHO AS ILLUSTRATED BY A ' MASIFR GRADING PLAN ARE TO BE SHOWN. 2. ALL SPOT ELEVATIONS DEPICTED ARE FLOWLHNE UNLESS OTHERWISE NOTED. 3. ALL CURB AND GUTTER SHAH BE 'QUIT 1 GURB AND GUTTER' / UNLESS OTHERWISE NOTED. n Q Sa ` 4. A MIN AWE OF 0.511 TO BE PRONCED ALONG THE ROW HNE m n OF ALL CATCH CURB AND GUTTER AND F5[ ACROSS ASPHALT O + N PAWMENT. THE MAX. SLOPE ACROSS ASPHALT TO SR " 5. EWSDNG UNDERGROUND INSTALLATIONS AND PRVATE UTIUTES m SHOWN ARE INDICATED ACCORDING TO THE BEST IMF..... N ; a• t AVMLABIE TO ME WONDER. THE ENONEER DOES NOT WARAMIEE 1HE ACCURACY OF SUCH INFCRMATW. SOM E E FFI Ijjj DRIES (WATER, POWER. GI STORM DRAIN, SANITARY SEWER. / PRONE, M MAY NOT BE STRAIGHT ONES W AS INDICATED ON > I THE PLANS. THE CONTRACTOR SHALL CALL ALL UIII TY N i ° COMPANIES BEFORE EXCAVATION FOR EMU LOCATIONS pp A \ °. AIL WORK i0 BE ACCOMPLISHED IN STRICT ADHERENCE WITH O ALL LOCK ORDINANCES, CITY OR STATE. Idh H I 1. CONTRACTOR TO COORDINATE ALL WORK WITHIN PU&IC w 111 RIGHT -a -WAY WITH THE APPROPMATE UPutt COIPANIES T,y "" RECORD SU DRAINAGE 1 AS OF 5=17*2007 Y _AB-BULT 40F F1fV. a \ n Z IB \ I i \ � I a -I- m m m / I U II c um ��L N '/ I � \ \ City of Fort Collins, Colorado Y Z Z \ ununPI AL/'/', w \_ APPRO d } PRdMEO UNDER NE DIRECT 91ARN9g1 OF Y GHaa Dute ~ Z ' CHEC BY: &: WWws xo:Ie.a uHlleyQCHECKEDBY:� ,rabic m Of Stammts Ut y Dab Q D CHECKED BY: AIAUtht k Fmm Utllty Cab00) CHECKED BY: AA � a' PcI RS- rvaetkn Dab Ly Gflee CHECKED BY: T P Dab SHEET 7 OR 20 aSPM v E OAR No, »BM CHECKED BY: nT Mp OI O.x aolplKl pob JOB NO. 38488.09