HomeMy WebLinkAboutSite Certifications - 04/29/20071 jVOrth Star STORMWATER
Aftw design, i n c. RECEIVED
APR 2 6 2007
April 24, 2007
Jay Barber
City of Fort Collins
700 Wood Street
Fort Collins, CO 80522
Dear Jay,
This letter is to certify the detention and water quality pond at Enterprise Car Rental. The
approved stage -storage table for the pond is attached with the as -built -volume for the
pond at the bottom of the page. The information presented is based on topographic
survey of the detention ponds provided by King Surveying (copy attached).
The volume achieved in this pond appears to meet or exceed the requirements set forth in
the approved drainage report and plans. Water quality volume has been provided per the
approved plans with an as -built water surface elevation of 4995.55, compared to an
elevation of 4996.55 as designed. The total volume of 0.184 acre-feet is achieved at an
elevation of 4997.20, compared to an elevation of 4997.90 as designed. Therefore, the
pond provides more volume than was designed and is acceptable as constructed.
Please call me if
Si
li
or if you need any additional information.
O REC,�S�
�P KRp'•:°9
I AL i
awoa S Go/Jc
700 Automation Drive, Unit I Windsor, Colorado 80550
970-686-6939 Phone 970-686-1 188 Fax
LOCATION:
PROJECT NO:
COMPUTATIONS BY:
SUBMITTED BY:
DATE:
Outlet invert
WQ Volume
Detention Volume
DESIGN POND VOLUME
Enterprise Car Rental
288-01
ppk
North Star Design
4/26/2007
100-Year Detention Required =
Water Quality =
Total Required=
1474 Cu ft
539 Cu ft
1474 Cu ft
Stage
(ft)
Surface
Area
(ft')
Incremental
Storage
(ac-ft)
Cummulative
Storage
(ac-ft)
4994.00
0
0
0
4995.0
161
0.00
0.00
4996.0
355
0.01
0.01
4996.55
499
0.01
0.01
4997.00
617
0.01
0.02
4997.90
915
0.02
0.03
4998.0
948
0.02
.0.04
4998.5
1090
0.01
0.05
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
ASBUILT 4/23/07
Outlet invert
WQ Volume
Detention Volume
Stage
(ft)
Surface
Area
(ft)
Incremental
Storage
(ac-ft)
Cummulative
Storage
(ac-ft)
4993.40
0
0
0
4994.0
222
0.00
0.00
4995.0
355
0.01
0.01
4995.55
437
0.00
0.01
4996.0
504
0.01
0.02
4997.00
676
0.01
0.03
4997.20
737
0.00
0.03
4998.0
980
0.02
0.05
STORMWATER
RECEIVED
APR 2 6 2007
305
539
785
1470
1562
2071
548
758
1346
1487
2169
PROPOSED ASPHALT PAVEMENT
TYPE L BURIED RIPRAP (4'x12'). TOP OF
RIPRATP & SOIL TO BE FLUSH WITH BOTTMOF
OF DITCH. SEE DETAIL, SHEET 3.
PRECAST OR CAST IN PLACE HEADWALL
TO BE FLUSH WITH EXISTING DITCH BANK.
SEE DETAIL, SHEET 3 FOR CAST IN PLACE
HEADWALL.
I N V= 93.39
93.24
31.0 LF 15" RCP (CLASS III) AT —\
2% SLOPE
10' LONG SPILLWAY. SEE
DETAIL.
OUTLET STRUCTURE. SEE
DETAIL. INV=94.88
Y 93.40
INSTALL CURB. MAINTAIN TOP
OF CURB ELEVATION AT 98.50 STOIM".INLET
TC F Gh TE=4997 38
BOTTOM O S1 UCTU-4993,70
NOTE- GRATt S C
161 �
INSTALL GRAVEL FXIiN55
FRONT OF OUTLET STIRRE
DURING CONSTRUCTION. REMOVE —
AFTER CONSTRUCTION IS
COMPLETE.
PROPOSED EDGE OF ASPHALT
RELOCATED TELEPHONE SERVICE AS
NEEDED THROUGH POND AREA
o °o
A
_x
15
x 499 .26
GND 15" RCP
.XX1,
99
0Pi
.x 4997.92
/
IbU
—IT1 1
U 1 f Som ~ ` \ 4j P,
147 \ \
x 49 40 v a\\ 1
GIN
4995 \ N _.
10 5 0 10 20
SCALE: 1" = 10'
49,90
8
156 }
G D01
U)
Y \ ;u Q
m aD
mg
` `�' •y _ .�-' ..emu � 1 .�-'V
9 49 _!T = -4995— f.
)P1 .4997
\15
X 4998 /
TOP 1 .,. n o - � -.. _ - ---
,y Al I \\- ASPHALT LIMITS
0) /�
157
SF SILT FENCE