HomeMy WebLinkAboutSite Certifications - 06/22/1998AIRES
ASSOCIATES
June 18, 1998
Mr. Basil Hamdan
City of Fort Collins Water Utilities
235 Mathews Street
Fort Collins, Colorado 80522
Re: Sterling House drainage certification
Dear Basil,
I visited the site of the above -referenced development on June 18, 1998, to check the drainage facilities
for compliance with the drainage plan. This letter summarizes my findings. I have attached a copy of
the drainage plan with surveyed elevations and my field notes for your review.
In general, all as -built elevations are within a couple of tenths of the design.elevations. Site drainage is
not generally impeded by variations from the design elevations. Variations from the design include:
• The sidewalk at the northwest corner of the project does not dip down to conform to a drainage
Swale as designed; however, the contractor placed a 6" pipe under the sidewalk to facilitate
drainage. The top -of -sidewalk elevation is approximately 86.7, which is 1.3 feet lower than the
building first floor, so it the pipe clogs, water would flow over the sidewalk before flooding the
building.
• The general overland swales along the north side of the building are slightly flatter than designed
(1.4% to the west and 1.6% to the east).
• The riprap pad at the north end of Pond 1 has been replaced by a concrete pan extending to the
pond outlet.
• The detention pond spillway elevations were raised by 0.3 feet, to 81.4. Corresponding detention
pond volumes total-13,538 ft3 vs 14,040 ft3. This corresponds to a shortage of 502 ft3, or 3.6%. The
increase in potential 100-year water surface elevations should not pose a problem as all ponding
would still be contained on -site, and there will continue to be 1 foot of freeboard.
• Although a 4 inch orifice was originally installed in the outlet box for Pond 1 in accordance with the
design, a 12 inch diameter hole has since been sawed into the box. Thus, the current orifice
diameter for the pond outlet is 12 inches.
This summarizes my findings. If you have any questions, or need clarification, please give me a call.
Sincerely,
we A e 1 & Associates, Inc.
Scott Qu n, P.E.
Civil Enqi er
SQ:dmm
Enclosure
Owen Ayres & Associates, Inc.
Engineers/Scientists/Surveyors
3665 JFK Parkway, Building 2, Suite 300, P.O. Box 270460, Fort Collins, CO 80527
(970) 223-5556, Denver Metro (303) 572-1806, FAX (970) 223.5578
R
6hamdan.ltr
34-0536.00
Printed on recycled paper
i
9
Description: Pond 2, Ft Collins Sterli ng house constructed
scale (ft.hn.): 0
SURFACE DELTA CUM. CUM.
ELEV. AREA (in) DEPTH AREA VOLUME VOLUME VOLUME
ft. sq. in. ft. Acres Acre-feet Acre-feet Cf
79.2
0
0.00
0.000
0.020
0.000
0
80.0
3220
0.80
0.074
0.105
0.020
859
81.0
6119
1.80
0.140
0.060
0.125
5451
81.4
6888
2.20
0.158
0.033
0.185
8051
81.6
7400
2.40
0.170
0.218
9480
0
0
0
0
0
0
0'
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0 ..
0
0
0
0
0
0
0
0
0
0
Description: Pond 1, Ft Collins Sterli ng house constructed
scale (ft.lin.): 0 i
SURFACE DELTA CUM. CUM.
ELEV. AREA (in) DEPTH AREA VOLUME VOLUME VOLUME
ft. sq. in. ft. Acres Acre-feet Acre-feet Cf
78.4
53
0.00
0.001
0.005
0.000
0
79.0
794
0.60
am
0.029
0.005
210
80.0
1784
1.60
0.041
0.053
0.034
1466
81.0
2903
2.60
0.067
0.029
0.087
3787
81.4
3402
3.00
0.078
0.016
0.116
- 5047
81.6
3705
3.20
0.085
0.132
5758
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
NOTES,
1O TRENCH DRAINS SHALL BE 17- WIDE WITH GRATED COVER: mDEETEX'-3990-E
STYLE A (OR APPROVED EQUAL). SEE DETAIL SHEET 7.
O PONDS SHALL BE GRADED WIN 4:1 SIDE SLOPES (MAX)
O CWRTYARD CATCH BASINS SHALL GE NDS STYLES IF1100 AND ,R80D
(CR APPROVED EWAL).
115
N� J
1
I FORT.
DSUBBASIN DESIGNATION0.9SUBBASIN AREA
lk;40f
BRIC Q DESIGN POINT
00 NOi BURY
!' TYPE II FlITFA MAIERI.LL OIN INLET
RIPRAP SLOPE: PARKING LOT -POND 1 ADD CLEArvWT
Nfi SECTION C-C
OMH MANHIXE
}-STM- STORM SEMER W/FES
BASIN BOUNDARY
T -4985- EXISTING CONTOUR
-85- PROPOI CONTOUR
- - - • ROOF DOWNSPOUT LOCATION
61
4
II
V
. DM.
PO'
30 0 30 60
pm
SCALE: 1 "=30'
a11410
4'
STORM SEWER TABLE
➢E6CP.IPTIQI
➢,NIFTIER (➢0
DISTANCE (LF)
SLOPE (U
PIPE MNTEg1g4975�
INVEST
INVERT OUT
RIM ELEVATION
➢ESCRIPTIWI
POND
OUTLET
4978.40
�ET
to
IN
RCP
MR-1
497&N
4981.90
MI
IB
290
L00
RCP
MI
497SM
499Q00
MF2ExIsTING
18
10
END
RCPINLET
4974.74 xe
EINLETDOUTFALL
4980.W
DUTFALL
12
206
I'm
X6E
IWI
49BIUM •
498650
IN-1
x 2
IN-2
12
20
2.00
NDPE
4981
4y81.61 x
4906W
Ix-3
W 3
12
I6
2.W
RIPE
I983.W
498166 a
4986.30
1. ALL HOPE PIPE SHALL BE RATED FOR H-20 LOA➢INC WITH NOMINAL COVER
INDICATES INVERT ELEVATION AT THE MAIN
^ xx EXISTING INVERT
w 2. ALL RCP PIPE SHALL BE CLASS III EXCEPT AS INDRATED ON THE PROFILE BELOW,
g
m€
n
M�
+
�m
1_
s
04
x
ffi4gS985
4985
oFn
4,
c
I A5
9), a
< z
u
S
v-
EXIST
GRADE
m
¢-�..z
t w
F9B0
100-YEAR
XCL
4980
T.
"O$BR
___
-190-J.F•.iB°_
YI.05..- _.•
- _
_ -
_.._.
F9788RCP
4975
lu M1 Iari
KITH_
A$ -V_ I P_
F
M TA r T
4970
_
STAR S
IP]0
497C
DETEN"ION POND SUMMARY
STORM SEWER PROFILE'
HORIZONTAL SCALE, 1'=30'
VERTICAL SCALE, 1'=5'
POND 1
POND 2
TOTAL
FRO�N)DED
100-YEAR VOLUME ; OF
PRONDED�R-EWIRED
1 9,47CO F '.3,900 OF
PRO`fDED
,a,04B CIF
-- -rOND
1
POND 2
NOTES --_
100-YEAP 'YS. OEV.
81. 1
81 `r
FOR ON -SITE DETENTION
1W-TEAR AS. ELEV.
81.6
81.6
WITH OFF-SIIE FLOW
1W-YEAR RELEASE RATE
0.8 CFS
B.B CFS
7.5 CF$
ON -SITE ALLOWABLE RAZE
OVERFLOW FROM OFF -SITE
TOTAL RELEASE FROM POND
RUNOFF SUMMARY
BASIN
DESIGN
POINT
AREA
(AC.)
010
(CFS)
C10
COMP.
DISC
(CFS)
C100
COUP.
A
1
033
1.0
OJ2
1.7
OJ7
a
2
0.53
2.1
0.58C
0.47
4.6
0.52
D
0.42
2.6
0.47
!
$0.521.2
133
E
4
0.90
0.9
0.95
OSt
6
0.61
t 1
0.66
052
0.20
0.2
111
Y;P rv.IlwiPOI
IV r•..,A 4lZ. / . DESIGN POINT 3 INCLUDES
BASINS
A B. D.
ff'"' AND OFSIM
DRAINAGE FROM
SWALE
AT WEST PRIM. LINE.
FOND"1_5N
ble. 9w.+Ae,+Hh 6Aws,
POND
NT5 S
MIR TOP OF BERM
EMERGENCY DVERTI
FESJ79
(i
it
UF.24' 1
1 OUTLET (SEE OCTAL THIS 9NFEY)
PON
_
_
'
q1 Fc+7u
DETM M9 `
Ir�
O,IMNAGE I'
1
•
It - - �$
RLPLrc"DF
-
F'
L
f
4 �1
el a
- s 1 -I�LLE
I1(IC•Bt66
-IRENCH CHAIN
----���
LL.78.40
R UP 16 q5 . ,.C% .r IS P...� 1
f �^� 1 Y""""' r20' MANAGE AND UTUTY EASEMENT
ENFAQN(1, OVECFLOw /It tzl*+1ljl Ca.II- EASEMENT TO BE DEDICATED BY PLAT
cAEs A EsQV W.. S
�lI£E12'-CBiUq'41 TYPE L-RPRI➢-
B (a�ol`veT) mlmtow
290 LF 187 RCP 04. _
+
10 LF Is a6,
DRIVE - - - - -SAN- -s ,ax - -
✓
- -- .-- - _- _ -- --W_
_ YN
-
-
LLI
Q
W
- _SAN
-
-
/I
- -
NV• 65
•.r 9.
X
IiTE TNrs �.,-a-�
Gv:1
0
dR
a'
TEP OF BERM (EL VARIES)
MIN ELEV.•82,3
C I -CREST OF OhRFIOW EL•81.6
�, ' PTO RULE MINE
300000000
SIGNEDIr TYPE L RIPRAP
Y SEE EMERGENCY WERFLOM' DUAL BELOW
/-GRATED INLET
USE TYPE 13 INLET BOX
NOTE: SEE OUIIET BOX DEENL
H
Ole (GRATED MUSTET 7TYPE 13)
INV MY EL•78.0
07'
3' TOPSOIL J / / L- FILTER FABRIC
LL 4' TYPE II FILTER MATERIAL
12' TYPE L RIPRAP
EMERGENCY OVERFLOW
N-fi SEC71ON B--B
1-
I—j4'0'
MOI
1. CONCRETE WITH FIBERMESH REQUIRED.
2. EXPANSION HINTS SHALL BE INSTALLED
EVERY 100'.
/ 3. CONTRACTION JOINTS SHALL BE INSTALLED
EVERY 5',
4. FLOW LINE SLOPE = SEE PLANS
5. SUBGRA➢E` 95% RELATIVE COMPACTION 6- DEEP.
TRICKLE CHANNEL DETAIL
NTS
m
O
�E N
jr- I
Q
a/ N
YL 0
n
O O
N N
J Q m
O O
O
ce 0�
z
U O
D
m w
W
3
m=
V
w
�Z
0J
0
O
Z Q
`
ZV
as
aH
w
w0
a
LL
z
,H
YI
Q
cc
0
MMEECi No 96471.01
FIE
DRAINAGE
DESCN BY PRY
ORANN
BY PNV
CBECIRU BY DOB
,SAE DATE 01-15-96
SESSIONS 02-06-97
REV,
BUILDING FWTPRINT
3nZ27
CITY WMMENTS
4/17/97 CITY COMMENTS
5/30/97 an COMMENTS
COMMENTS
91EEf 4 DF 7 I