Stormwater Management Report0 0
4
STORMWATER MANAGEMENT REPORT
IT
GARDENTIME / BARRETT AUTO SALES
NEW DISPLAY AREA
Town of Queensbury, New York
Warren County
Prepared by: NACE ENGINEERING, P.C.
169 HAVILAND ROAD
QUEENSBURY, NY 12804
homas W. Nace, P.E.
August 29, 2000
File: #47309
STORMWATER MANAGEMENT REPORT
FOR
GARDENTIME / BARRETT AUTO SALES
INTRODUCTION
The existing site is between Dix Avenue and Quaker Road. The site is relatively flat and has
previously been filled with well -drained granular soils.
The is currently no development on the site.
The proposed development consists of display areas for recreational vehicles and storage sheds
and gazebos. These areas will be gravel surfaced. All access roads and parking areas with gravel
with the exception of the main access apron off of Quaker Road.
DRAINAGE METHODOLOGY
Due to the well -drained characteristics of the sandy fill on this site, all drainage generated from
impermeable areas will be recharged into the ground through infiltration. Runoff from the
majority of the display and parking areas will be collected in shallow depressions and allowed to
infiltrate. The storage volume of these depressions has been designed to accommodate the runoff
from a 50-year storm without utilizing the infiltration capacity.
A few small areas of the site (namely subcatchments #1 & #3) will be allowed to runoff directly
to the existing ditchlines along Quaker Road as they presently do.
The proposed 30 inch culvert for access across the existing ditchline has been sized by including
the existing, upstream 24 inch cmp in the analysis and inputting a fictional subcatchment to keep
the 24 inch crop full.
CALCULATIONS I
All computations SCS TR-20 HydroCAD.
50 year storm event - Type II rainfall = 4.8".
Soil conditions — sandy fill, no groundwater or mottling observed to 3+ feet.
Runoff rate and volume computations for the 50-year storm event have been completed for the
proposed site development.
' CONCLUSIONS
Based upon the attached HydroCAD analysis, the proposed shallow infiltration basins have
sufficient capacity to manage all runoff generated during a 50-year storm event without
overflowing.
The analysis shows that the proposed 30 inch culvert has a capacity of approximately 40 cfs
which is much more than the predicted 11.23 cfs which the pipe will be required to handle.
4
STORNIWATER NIANAGEMENT REPORT
FOR
GARDENTIME / BARRETT AUTO SALES
NEW DISPLAY AREA
HydroCAD RESULTS
DEVELOPED CONDITONS
f , ' •
Data for 47309 — GARDENTIME DISPLAY AREA Page 1
TYPE iI 24—HOUR RAINFALL= 4.80 IN
Prepared by NACE ENGINEERING, P.C. 30 Aug 00
HydroCAD 5.11 000576 (c) 1986-1999 Applied Microcomputer Systems
WATERSHED ROUTING ________ --------
10 3 10�'�x�sS. Z4G<�lP
W
lO--�, 1� i �_ �ivo�o5f d �� Co1VG i
T
O
O—�A
V SUBCRTCHMENT REACH POND li LINK
Data for 47309 - GARDENTIME DISPLAY AREA Page 2
TYPE TI 24-HOUR RAINFALL= 4.80 IN
Prepared by NACE ENGINEERING, P.C. 30 Aug 00
HydroCAD 5.11 000576 (c) 1986-1999 Applied Microcomputer Systems
SUBCATCHMENT 1 QUAKER ROAD FRONTAGE S. OF ENTRY
PEAK= .37 CFS @ 11.94 HRS, VOLUME- .02 AF
SO -FT CN SCS TR-20 METHOD
19800.00 39 LAWN TYPE II 24-HOUR
4400.00 98 QUAKER ROAD PAVEMENT RAINFALL= 4.80 IN
24200.00 50 SPAN= 10-20 HRS, dt=.1 HRS
Method Comment Tc (min)
TR-55 SHEET FLOW ACROSS LAWN 5.5
Grass: Dense n=.24 L=40' P2=2.4 in s=.05
SUBCATCHMENT 2 MAIN DISPLAY AREA
PEAK= .16 CFS @ 12.90 HRS, VOLUME= .06 AF
SO -FT CN SCS TR-20 METHOD
25200.00 55 GRAVEL PARKING TYPE II 24-HOUR
125200.00 39 GRAVEL DISPLAY AREA AND LAWN RAINFALL= 4.80 IN
150400.00 42 SPAN= 10-20 HRS. dt=.1 HRS
Method Comment Tc (min)
TR-55 SHEET FLOW ACROSS DISPLAY AREA 51.6
n=.25 L=200' P2=2.4 in s=.005 '/'
SUBCATCHMENT 3 NORTH END OF SITE
PEAK= .06 CFS @ 12.43 HRS, VOLUME= .02 AF
SO -FT ON SCS TR-20 METHOD
34100.00 39 GRASS TYPE II 24-HOUR
7800.00 55 GRAVEL PARKING RAINFALL= 4.80 IN
41900.00 42 SPAN= 10-20 HRS, dt=.1 HRS
Method Comment Tc (min)
TR-55 SHEET FLOW ACROSS LAWN 26.4
Grass: Dense n=.24 L=180' P2=2.4 in s=.02
SUBCATCHMENT 4 NORTHWEST SIDE OF SITE
PEAK= .12 CFS @ 11.99 HRS, VOLUME= .01 AF
SQ-FT ON SCS TR-20 METHOD
8840.00 55 GRAVEL DRIVE TYPE II 24-HOUR
17100.00 39 GRASS RAINFALL= 4.80 IN
25940.00 44 SPAN= 10-20 HRS, dt=.1 HRS
Method Comment Tc (min)
TR-55 SHEET FLOW ACROSS DRIVE 4.7
n=.25 L=20' P2=2.4 in s=.02 '/'
-Data for 47309 - GARDENTIME DISPLAY AREA Page 3
TYPE II 24-HOUR RAINFALL= 4.80 IN
Prepared by NACE ENGINEERING, P.C. 30 Aug 00
HydroCAD 5.11 000576 (c) 1986-1999 Applied Microcomputer Systems
SUBCATCHMENT 10 DRAINAGE CREATED TO FILL EXIST. PIPE
PEAK= 22.21 CPS @ 11.97 HRS, VOLUME= 1.19 AF
ACRES CN
5.00 85 FICTIONAL DRAINAGE TO FILL PIPE
DIRECT ENTRY
Segment ID:
SCS TR-20 METHOD
TYPE II 24-HOUR
RAINFALL= 4.80 IN
SPAN= 10-20 HRS, dt=.1 HRS
10.0
Data for 47309 - GARDENTIME DISPLAY AREA Page 4
• TYPE II 24-HOUR RAINFALL= 4.80 IN
Prepared by NACE ENGINEERING, P.C. 30 Aug 00
HydroCAD 5.11 000576 (c) 1986-1999 Applied Microcomputer Systems
REACH 1 NEW 12 INCH CULVERT AT ENTRANCE
Qin = .37 CPS @ 11.94 HRS, VOLUME= .02 AF
QOut= .35 CFS @ 11.97 HRS, VOLUME= .02 AF, ATTEN= 5%, LAG= 1.5 MIN
DEPTH END AREA DISCH
(FT)
(SO -FT)
(CPS)
0.00
0.00
0.00
.10
.04
.07
.20
.11
.29
.30
.20
.64
.70
.59
2.74
.80
.67
3.20
.90
.74
3.49
.94
.77
3.52
.97
.78
3.49
1.00
.79
3.28
REACH 2
12" PIPE
n= .01
LENGTH= 60 FT
SLOPE= .005 FT/FT
EXISTING OPEN DITCHLINE
Qin = 11.31 CFS @ 12.00 HRS, VOLUME= 1.23 AF
Qout= 11.23 CFS @ 12.05 HRS, VOLUME= 1.23 AF
DEPTH END AREA DISCH
(FT) (SO -FT) (CFS) 3' x 4' CHANNEL
0.00 0.00 0.00 SIDE SLOPE= .33
.40 1.68 1.25 n= .07
.80 4.34 4.70 LENGTH= 160 FT
1.20 7.96 10.78 SLOPE= .006 FT/FT
1.72 14.12 23.39
2.40 24.65 49.42
3.20 40.63 96.45
4.00 60.48 164.14
REACH 3
NEW 30 INCH CULVERT
Qin = 11.23 CFS @ 12.05 HRS, VOLUME= 1.23 AF
QOut= 11.23 CFS @ 12.07 HRS, VOLUME= 1.23 AF
DEPTH END AREA DISCH
(FT) (SO -FT) (CPS) 30" PIPE
0.00 0.00 0.00
.25 .26 .79 n= .01
.50 .70 3.30 LENGTH= 40 FT
.75 1.24 7.38 SLOPE= .005 FT/FT
1.75 3.67 31.57
2.00 4.21 36.85
2.25 4.65 40.19
2.35 4.79 40.56
2.43 4.87 40.18
2.50 4.91 37.70
STOR-IND+TRANS METHOD
PEAK DEPTH= .22 FT
PEAK VELOCITY- 2.7 FPS
TRAVEL TIME = .4 MIN
SPAN= 10-20 HRS, dt=.1 HRS
ATTEN= 1%, LAG- 3.5 MIN
STOR-IND+TRANS METHOD
PEAK DEPTH= 1.22 FT
PEAK VELOCITY= 1.4 FPS
TRAVEL TIME = 1.9 MIN
SPAN= 10-20 HRS, dt=.1 HRS
ATTEN= 0%, LAG= 1.1 MIN
STOR-IND+TRANS METHOD
PEAK DEPTH= .91 FT
PEAK VELOCITY= 6.9 FPS
TRAVEL TIME = .1 MIN
SPAN= 10-20 HRS, dt=.1 HRS
• Data for 47309 - GARDENTIME DISPLAY AREA Page 5
TYPE II 24-HOUR RAINFALL= 4.80 IN
Prepared by NACE ENGINEERING, P.C. 30 Aug 00
HydroCAD 5.11 000576 (c) 1986-1999 Applied Microcomputer Systems
REACH 10 EXISTING 24" DIA. CMP CULVERT
Qin = 22.21 CFS
@ 11.97
HRS, VOLUME= 1.19 AF
Qout= 10.96 CFS
@ 12.00
HRS, VOLUME= 1.19 AF,
ATTEN= 51%, LAG=
2.0 MIN
DEPTH END AREA
DISCH
(FT) (SO -FT)
(CFS)
24" PIPE
STOR-IND+TRANS
METHOD
0.00 0.00
0.00
PEAK DEPTH=
2.00 FT
.20 .16
.23
n= .024
PEAK VELOCITY=
3.9 FPS
.40 .45
.96
LENGTH= 150 FT
TRAVEL TIME =
.6 MIN
.60 .79
2.15
SLOPE= .008 FT/FT
SPAN= 10-20 HRS, dt=.1 HRS
1.40 2.35
9.18
1.60 2.69
10.71
1.80 2.98
11.68
1.88 3.06
11.79
1.94 3.11
11.68
2.00 3.14
10.96
Data for 47309 - GARDENTIME DISPLAY AREA Page 6
TYPE II 24-HOUR RAINFALL= 4.80 IN
Prepared by NACE ENGINEERING, P.C. 30 Aug 00
HydroCAD 5.11 000576 (c) 1986-1999 Applied Microcomputer Systems
POND 1 DETENTION POND SOUTHWEST SIDE OF SITE
Qin =
.16
CFS @
12.90 HRS,
VOLUME= .06 AF
Qout=
0.00
CFS @
0.00 HRS,
VOLUME= 0.00 AF,
ATTEN=100o, LAG=
0.0
MIN
ELEVATION
AREA
INC.STOR
CUM.STOR
STOR-IND METHOD
(FT)
(SF)
(CF)
(CF)
PEAK STORAGE =
2485
CF
94.0
500
0
0
PEAK ELEVATION=
94.4
FT
95.0
11600
6050
6050
FLOOD ELEVATION=
95.5
FT
95.5
15500
6775
12825
START ELEVATION=
94.0
FT
SPAN= 10-20 HRS, dt=.1 HRS
# ROUTE INVERT OUTLET DEVICES
1 P 95.4' 40' BROAD -CRESTED RECTANGULAR WEIR X 1.81
Q=C L H"1.5 C=1.75, 1.8, 1.8, 0, 0, 0, 0, 0
POND 2
DETENTION POND NORTHWEST
SIDE OF SITE
Qin =
.12
CFS @ 11.99
HRS,
VOLUME= .01 AF
Qout=
0.00
CFS @ 0.00
HRS,
VOLUME= 0.00 AF,
ATTEN=100o, LAG=
0.0 MIN
ELEVATION
AREA
INC.STOR
CUM.STOR
STOR-IND METHOD
(FT)
(SF)
(CF)
(CF)
PEAK STORAGE =
600
CF
94.0
700
0
0
PEAK ELEVATION=
94.2
FT
95.0
6840
3770
3770
FLOOD ELEVATION=
95.5
FT
95.5
8000
3710
7480
START ELEVATION=
94.0
FT
SPAN= 10-20 HRS, dt=.1 HRS
# ROUTE INVERT OUTLET DEVICES
1 P 95.4' 380' BROAD -CRESTED RECTANGULAR WEIR X 1.81
Q=C L H-1.5 C=1.75, 1.8, 1.8, 0, 0, 0, 0, 0
STORMWATER MANAGEMENT REPORT
FOR
GARDENTIME / BARRETT AUTO SALES
NEW DISPLAY AREA
DRAINAGE AREA DELINEATION
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