TM-7.1_STORMWATER TREATMENT CALCULATIONSv
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CISTERN SIZING CALCULATIONS BY DRAINAGE AREAS:
Drainaae Area 1 (DA -1) Volume Based Treatment Measures
using the URQM Approach
Step 1. Drainage Area for BMP: 17.62 acres
Step 2. a. Impervious Area: 9.92 acres
b. Impervious ratio: (i) 56.3%
Step 3. Watershed runoff Coefficient Cw = 0.382
(Cw = 0.858i3-0.78i2+0.774i+0.04)
Step 4. Mean Annual Precipitation 16 inches
Step 5. Closest Rain Gage San Jose Airport
Gage
MAPgage
(P6)gage (in)
San Jose Airport
13.9
0.512
Palo Alto
13.7
0.522
Morgan Hill
19.5
0.76
Step 11. Size Cistern
Drainaae Area 2 (DA -2) Volume Based Treatment Measures
using the URQM Approach
Step 1. Drainage Area for BMP: 11.32 acres
Step 2. a. Impervious Area: 7.17 acres
b. Impervious ratio: (i) 63.3%
Step 3. Watershed runoff Coefficient Cw = 0.435
(Cw = 0.858i3 -0.78i2+0.7741+0.04)
Step 4. Mean Annual Precipitation 16 inches
Step 5. Closest Rain Gage San Jose Airport
Gage
MAPgage 13.9
(P6)gage (in)
San Jose Airport
(P6)gage 0.512
0.512
Step 6.
Mean Storm Event Precipitation Depth
(P6)site
Morgan Hill
(POsite = (P6)gage X (MAPsite)/(MAPgage)
0.589 Inches
Step 7.
11a" regression constant
a= 48 hour 1.963
48 hour
a= 24 hour 1.582
a= 1.963
a= 12 hour 1.312
Step 8.
Maximized Storage Area
P,, =(a X Cw) X P6
0.442 inches
Step 9.
Volume of Runoff to be Treated
Design Volume = Po XA X 1ft/12in
0.649 acre -ft
28,254 cult
Step 10.
Double Volume for Back to Back Storm
1.566 acre -ft
1.297 acre -ft
68,223 cuff
56,509 cult
Step 11. Size Cistern
Drainaae Area 2 (DA -2) Volume Based Treatment Measures
using the URQM Approach
Step 1. Drainage Area for BMP: 11.32 acres
Step 2. a. Impervious Area: 7.17 acres
b. Impervious ratio: (i) 63.3%
Step 3. Watershed runoff Coefficient Cw = 0.435
(Cw = 0.858i3 -0.78i2+0.7741+0.04)
Step 4. Mean Annual Precipitation 16 inches
Step 5. Closest Rain Gage San Jose Airport
Gage
MAPgage
(P6)gage (in)
San Jose Airport
13.9
0.512
Palo Alto
13.7
0.522
Morgan Hill
19.5
0.76
Step 11. Size Cistern
Drainaae Area 3 (DA -3) Volume Based Treatment Measures
using the URQM Approach
Step 1. Drainage Area for BMP: 21.89 acres
Step 2. a. Impervious Area: 11.99 acres
b. Impervious ratio: (i) 54.8%
Step 3. Watershed runoff Coefficient Cw = 0.371
(Cw = 0.858i3 -0.78i2+0.7741+0.04)
Step 4. Mean Annual Precipitation 16 inches
Step 5. Closest Rain Gage San Jose Airport
Gage
MAPgage 13.9
(P6)gage (in)
San Jose Airport
(P6)gage 0.512
0.512
Step 6.
Mean Storm Event Precipitation Depth
(P6)site
Morgan Hill
(P6)site = (P6)gage X (MAPsite)/(MAPgage)
0.589 Inches
Step 7.
.,a" regression constant
a= 148 hour 1 1.963
48 hour
a= 24 hour 1.582
a= 1.963
a= 112 hour 1 1.312
Step 8.
Maximized Storage Area
Po =(a X Cw) X P6
0.504 inches
Step 9.
Volume of Runoff to be Treated
Design Volume = Po XA X 1ft/12in
0.475 acre -ft
20,693 cult
Step 10.
Double Volume for Back to Back Storm
1.566 acre -ft
0.950 acre -ft
68,223 cuff
41,386 cult
Step 11. Size Cistern
Drainaae Area 3 (DA -3) Volume Based Treatment Measures
using the URQM Approach
Step 1. Drainage Area for BMP: 21.89 acres
Step 2. a. Impervious Area: 11.99 acres
b. Impervious ratio: (i) 54.8%
Step 3. Watershed runoff Coefficient Cw = 0.371
(Cw = 0.858i3 -0.78i2+0.7741+0.04)
Step 4. Mean Annual Precipitation 16 inches
Step 5. Closest Rain Gage San Jose Airport
Gage
MAPgage
(P6)gage (in)
San Jose Airport
13.9
0.512
Palo Alto
13.7
0.522
Morgan Hill
19.5
0.76
Step 11. Size Cistern
- --- =----
HIVIP APPLICABILITY MAPF'
I
CITY OF CUPERTINO
h.
LLI
Legend
Continuously Hardened Channel
Major Creeks
Roads and Highways
Jurisdictional Boundary
Catchments Draining to Hardened Channel andlor Tidal Areas
Catchments and Subwatersheds 2� 65% Imperviousness
Sabwatersheds less than 650/:,
Resefvoirs in Santa Clara Basin
1-280
T fI� i '
l �
{ tellark R% ■
�' C1,1%Regaarf Creek
liyanr�lsprpr# Or
Columbus Av Clare re ,
Assume 25' Tall X 12' Wide Assume 15' Tall X 17' Wide Assume 15' Tall X 50' Wide Cam J 1`
Length = 190 ft Length = 165 ft Stevens5tCreek t`
9 9 Length = 95 ft �4��arvolr , � .
Total Cistern Storage Volume Total Cistern Storage Volume Total Cistern Storage Volume
.f -
57,000 cuff 42,075 cult 1 71250 cuff
1 �
ninTr--
FOR THE PURPOSE OF THIS STORMWA TER MANAGEMENT PLAN, THE SITE HAS BEEN
LOOKED A T AS THREE DRAINAGE AREAS RAINWA TER CISTERNS WILL BE DESIGNED
IN MORE DEPTH AND COORDINATED WITH THE PLUMBING ENGINEER TO WORK WITH
CONSTRUCTION PHASING, THE SITE SPANNING PUBLIC RIGHT OF WAY AND
IRRIGA TION DEMANDS. THESE CISTERNS WILL BE SIZED /NDI WDUALL Y BASED THEIR
RESPECTIVE DRAINAGE AREAS.
t*�
HYDROMODIFICATION MAP
N. T.S.
ninTr--
PROJECT IS EXEMPT FROM HYDROMODIRCA TION BECAUSE
IT IS LOCATED /N A WATERSHED THAT IS GREATER THAN
65X IMPERVIOUS.
Date' N owernh4rr 20 10
E Fiarrsestead Rd
SITE
DATE :03-27-2018 DATE MARCH 27 2018 QROFESS/p No. REVISION ISSUE DATE BY
CIVIL ENGINEERS SCALE: NTS TENTATIVE SUBDIVISION MAP SHEET
SANDISSURVEYORS � Q � �
PLANNERS DRAWN D SP � � No. C68315 STORMWATER TREATMENT CALCULATIONS VALLCO TOWN CENTER TM7ml
APPROVED BY: ND � Exp. 9/30/19
700 S. Winchester Blvd, Suite 200, Campbell, CA 95008 I P. 408.636.0900 I F. 408.636.0999 I www.sandis.net DRAWING NO.: C U P E RT I N O CALIFORNIA
. • CHAD J. BROWNING ��q�F C/VIS IO���P
215028 R.C.E. NO. 68315, EXPIRES 9-30-19 OF CALF
OF 61 SHEETS
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MAPgage 13.9
(P6)gage 0.512
Step 6.
Mean Storm Event Precipitation Depth
(P6)site
(P6)site = (POgage X (MAPsite)/(MAPgage)
0.589 Inches
Step 7.
.a" regression constant
a= 48 hour 1.963
48 hour
a= 24 hour 1.582
a= 1.963
a= 12 hour 1.312
Step 8.
Maximized Storage Area
P,, =(a X Cw) X P6
0.429 inches
Step 9.
Volume of Runoff to be Treated
Design Volume= Po XA X 1ft/12in
0.783 acre -ft
34,112 cuft
Step 10.
Double Volume for Back to Back Storm
1.566 acre -ft
68,223 cuff
Step 11. Size Cistern
- --- =----
HIVIP APPLICABILITY MAPF'
I
CITY OF CUPERTINO
h.
LLI
Legend
Continuously Hardened Channel
Major Creeks
Roads and Highways
Jurisdictional Boundary
Catchments Draining to Hardened Channel andlor Tidal Areas
Catchments and Subwatersheds 2� 65% Imperviousness
Sabwatersheds less than 650/:,
Resefvoirs in Santa Clara Basin
1-280
T fI� i '
l �
{ tellark R% ■
�' C1,1%Regaarf Creek
liyanr�lsprpr# Or
Columbus Av Clare re ,
Assume 25' Tall X 12' Wide Assume 15' Tall X 17' Wide Assume 15' Tall X 50' Wide Cam J 1`
Length = 190 ft Length = 165 ft Stevens5tCreek t`
9 9 Length = 95 ft �4��arvolr , � .
Total Cistern Storage Volume Total Cistern Storage Volume Total Cistern Storage Volume
.f -
57,000 cuff 42,075 cult 1 71250 cuff
1 �
ninTr--
FOR THE PURPOSE OF THIS STORMWA TER MANAGEMENT PLAN, THE SITE HAS BEEN
LOOKED A T AS THREE DRAINAGE AREAS RAINWA TER CISTERNS WILL BE DESIGNED
IN MORE DEPTH AND COORDINATED WITH THE PLUMBING ENGINEER TO WORK WITH
CONSTRUCTION PHASING, THE SITE SPANNING PUBLIC RIGHT OF WAY AND
IRRIGA TION DEMANDS. THESE CISTERNS WILL BE SIZED /NDI WDUALL Y BASED THEIR
RESPECTIVE DRAINAGE AREAS.
t*�
HYDROMODIFICATION MAP
N. T.S.
ninTr--
PROJECT IS EXEMPT FROM HYDROMODIRCA TION BECAUSE
IT IS LOCATED /N A WATERSHED THAT IS GREATER THAN
65X IMPERVIOUS.
Date' N owernh4rr 20 10
E Fiarrsestead Rd
SITE
DATE :03-27-2018 DATE MARCH 27 2018 QROFESS/p No. REVISION ISSUE DATE BY
CIVIL ENGINEERS SCALE: NTS TENTATIVE SUBDIVISION MAP SHEET
SANDISSURVEYORS � Q � �
PLANNERS DRAWN D SP � � No. C68315 STORMWATER TREATMENT CALCULATIONS VALLCO TOWN CENTER TM7ml
APPROVED BY: ND � Exp. 9/30/19
700 S. Winchester Blvd, Suite 200, Campbell, CA 95008 I P. 408.636.0900 I F. 408.636.0999 I www.sandis.net DRAWING NO.: C U P E RT I N O CALIFORNIA
. • CHAD J. BROWNING ��q�F C/VIS IO���P
215028 R.C.E. NO. 68315, EXPIRES 9-30-19 OF CALF
OF 61 SHEETS
rrl_. r. 1 04cnnnl /el rn/n/A/rrn/A1n1 /nl n/ nn/ 71 "`llrrr rrrl r/-AIrArll/r IJAnl -rni iu/nrrn rnrnrl/rAIr n/ AAl -l... - n-1_.Ii_._ n7 nnan 7_ n7-.__ Copyriqht n 2018 by Sandis
flu. ✓. 1Ll✓VLV 11 T/ L/VullvLL11//YV 1`L/ / Ln/V ✓L l✓ 1t✓'/ -,l/LL/ -,Ll 1/LIV/n/I VL IV/nl 1/IV/ / ✓ I✓l1/Vl rrn/L/x ll%Ln/IV/Llv/ I Ln/V. VVVv u,ULG. mum L✓/ LV/V ✓.L✓�ll/I/ op/l/lJ.