HomeMy WebLinkAboutSite Certifications - 03/17/2006INTERWEST M CONSULTING GROUP
May 15, 2006
Mr. Jay Barber
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, CO 80522
Re: Sonic�Drive4n/-L-ot*Tower Shoppes PUD-- Horsetooth-and-Timberline
Detention Pond Certification
I.C.G. Project No. 1025-021-00
Dear Jay,
We are pleased to submit this letter which certifies that the constructed extended detention basin
for The Sonic Drive -In / Lot 4 Tower Shoppes P.U.D. located at the corner of Horsetooth Road
and Timberline Road is in general conformance to the approved drainage and grading plan by
Interwest Consulting Group dated/approved on November 16, 2005. King Surveyors surveyed
the new water quality pond and outlet structure on Wednesday, May 10, 2006. The result 'of this
survey indicates that the new water quality pond has adequate detention volume per the approved
"Final Drainage and Erosion Control Report for The Sonic Drive -In / Lot 4 Tower Shoppes
P.U.D." dated November 16, 2005. The attached calculations show the designed volume of 0..17.
ac-ft and the constructed volume 0.20 ac-ft.
During our site .visit on Friday, May 12, 2006 it appeared that all permanent erosion control
measures are in place and are constructed per the approved plan and drainage report as
mentioned above. We have attached a record contour drawing and stage -storage calculations for
the new extended detention basin for your review.
If you have any questions or need additional information please do not hesitate to contact me
directly at 970.674.3300, ext 105.
Sincerely,
Je n' er P. ng, P(
Attachments
cc: John Slack, WW Reynolds
David Beard, Sonic
1218 W. ASH, STE. C
WINSDOR, CO 80550
(st ( b-s
J
EXTENDED DETENTION BASIN
Stage/Storage
LOCATION: Tower Shoppes Drainage Study
CONIPUTATIONS BY: J. Zung
SUBMITTED BY: INTERWEST CONSULTING GROUP
DATE: 5/12/2006
V = 1/3 d (A + B + sgrt(A`B))
where V = volume between contours, fl3
d = depth between contours, It
A = surface area of contour
Lot 2 + Lot 4 + west Lot 1
Sub -basins A+B+C
Stage
(ft)
Surface
Area
(ft),
Incremental
Storage
(ao-ft)
Total
Storage
(ao-ft)
33.1
0
0.00
0.00
34.0
59
0.00
0.00
35.0
737
0.01
0.01
36.0
2289
0.03
0.04
37.0
4387
0.08
0.12
37.5
5143
0.05
0.17
38.0
5899
0.06
0.23
38.5
5977
0.07
0.30
Water Quality Capture Volume Required = 0.17
AS -BUILT SURVEY 5110106
Stage
(ft)
Surface
Area
(fe)
Incremental
Storage
(ao-ft)
Total
Storage
(ao-ft)
33.29
0
0.00
0.00
34.00
288
0.00
0.00
35.00
1307
0.02
0.02
36.00
2912
0.05
0.07
36.69
3458
0.05
0.12
37.00
4673
0.03
0.14
37.50
5661
0.06
0.20
38.02
6612
0.07
0.28
38.50
7045
0.08
0.35
Water Quality Capture Volume Provided = 0.20
6"+/- Freeboard available
WQCV elev
spill elevation
berm elevation
WQCV elev
spill elevation .
berm elevation
Q
tower shoppes pond volumes
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