HomeMy WebLinkAboutTract 18472HYDROOGY STUDY
FOR
TRACT IOAP NO. 18472
Northeast Corner of Merrill Avenue & Catawba Avenue
.. City of Fontana
County of San Bernardino
State of California
4"
PREPARED BY
C.2: & Inc.
Civil Engineers and Land Surveyors
8880 Benson, Ave., Suite 100
Montclair, California 91763
(909) 941-1791
JUNE 20, 2008
■
c�
Z
V
~
U
a
W d
~
o
w
c7
Z
o
Q
W
0
M
W
W
U
W
O
I
IL
00
0 ~
00
O LL
N
CJ
W N
O
O
L17
00
IL
U
g19
D U
a �
.20
�
dJ
� r
U r
N �
U
0
•w
�' J
INTRODUCTION & CONCLUSIONS:
The purpose of this report is to present hydrology study for Tract Map No. 18472.
Tract Map No. 18472 consists of 8 residential lots 2.20 acres in size. There is an
existing house and garage located on the site that will be removed before
w
grading operations begin. The project is bounded on the south by Merrill
Avenue, on the west by Catawba Avenue, on the north by 4 residential lots facing
Catawba Avenue, and on the east by a single residential lot facing Ceres
Avenue.
r In its existing condition, the site has a single residential house that will be
removed. The existing area slopes almost directly to the south. At present the 4
lots (A-1) located to the north all drain directly westerly to Catawba Avenue. The
area (A-2) directly to the north and easterly of the 4 lots is barren with the
exception of a single house on the 1.1 acres and drains directly southerly. The
drainage run-off from this area and the site area (A-3) drain southerly into Merrill
Avenue. The combined pre -development run-off for a 100 year storm is 12.33
cfs. The construction, as shown on the grading plan, of the property line wall
adjacent to area A-2 will include leaving the cement mortar out of the vertical
joints of the first course of blocks at ground level. This will allow the natural
drainage pattern to flow through.
The amount of existing peak -flow is not affected by the proposed development of
the site. The post -development peak -flow is 11.52 cfs. versus the pre -
development peak -flow of 12.33 cfs. The amount of barren terrain in the existing
condition significantly affects the totals.
F
8
m
a.
DESIGN DATA
d
0
0
I.
41
e
qw
4.
M
e
t.
44
V
A
F
I"
ft
DESIGN CRITERIA
The analysis and conclusion of this study were prepared using the maps and
charts from the San Bernardino County Hydrology Manual. A list of data used is
as follows:
• Storm Frequency
• Time of Concentration
• Rainfall Intensity
• Soil Designation — W
• 100 yr. 1 hour Isohyetals
100 -year storm
Figure D-1
Figure D-3
Figure C-13
Figure B-4
a
AN
0
IN
m
Jd
40
qm
41
i
JI IL
0 (:tKtS IL
MERRILL AVENUE
� SITE J� �
Q
Q
J Q �
c1A v
RANDALL AVENUE
IF---7AI 11 IF
VICINITY MAP
N.T.S.
HYDROLOGIC DATA SUMMARY:
.SUB -AREA
AREA
PRE -DEV.
PRE -DEV.
POST -DEV
POST -DEV
(AC)
Q100
TC
Qloo
TC
A-1
0.6
2.0
9.7
2.0
9.7
A-2
1.1
3.8
10.5
3.8
10.5
A-3
2.2
6.5
11.0
5.8
14.0
�r
40
w
0 /Mmm son mammon
noun align a
n NOW
♦ •
✓E .an
...... 'so ai f• mea • ..........'• ..• . a • a
)means ■ m■ a a\ ■ •■■a■ •• m
44006a• among
. e■ r.■s.an
a a►�, . • Rl
•
■■ : ' •
a on
long go ass • an aaI'D •
man a so ■ ° ■ , a
Ina a no' a • , ■ s
Imsome a... : C AVE ' • • Z . 1 •
Is
........ •m■..ee■ I: o ■ ■ a i as ■....♦ • nog• ' a '
an a
Sana• ��i �• i !' a ■ i�•�♦ a •
unman j : I� a a i•■ ■ •
a •Nei •■•' : �� • , ■ ■ pp al
AVE am ,h=♦♦m m y
• • 1•i. ! . . •�a.. a ...
' a■■ .s •m■■ a
■. ago • : ■.■s■e• ■n . ■ — ■ -
■ ■ ■ .■•w■. ens ■ e ■ 4 i
■ • •r �' ' • ; ; Mama. ; ; a g . —
r—_—
' �II l� `� 'a i : ala• : ■ ■ • w • ' a
■� ■ w' a �
• I I "�� a■ • • ms■ ■
• t ■: a t ■ •
no
I a I a a • •name. a a■ a
on a
■ a� ow a
g�■ •m ■ a ■a■ ■ a. • • ■ • • ■
■ A- •
■ ■ ■ammo• amemnons • a a • °° ■• ' • {i ■ ti ■ o
al ■ on ■ ■ a..s.f■ ■■ a■ow an ■. • ■ ■ • e MO
■ommaa■m■se • •maiomm■s • some a■■• ■ n■ u ■ ■ some a. • a:
• .woo.■ ■ • ■i ■ ■ ■ angle■ N a ■em■ ■■ ■ ■
w1 A ♦ ■Oma Sane■ • ■ • ■ ■ ■ •
el • I
N.
• . • muse•.. ; . • ■ • . MEMO •-1 1 •
• • ■ •a
• ■ ■
•
■
•
• r
a • ■ •
■
a
11�
i
■ms■ua• ■ .w--■■
• 1
■ a •■ ■■a■• a ■
•mama■f• •t■a ■ ■ a e ■a "Name ■ N■■ ■■o■ • ■ •■. ■ S■■ •
. a ■ . ■ . ■ . ■ % •
■ • w
of
•
lana° ' ■ • a• Somme ■■• ■ ■• ■•.N aa'-• .a ■..° ■ •■■ ■■ to ■t ■a.eoe ■■■ •1° ,
•a■ • \
•■■awe. 11111
•
•
■ _
'A{~.•
RV 4 all
•amy
■
■
G'�.siY'Y' ..••.i.5 � _
S`1
• s _
y
• _
I
Y:.� M •.
am
no
mmm,� ago
■ .
•
-5~
•
•
•
•
!
♦.
•
m
■
■
1
Sane :urs;: -
■
■
•
s a
■ ■Mom■•
■
■amts.■■ s•
■
m s s s
e
■somman ■ ■u
•
memo memo amuse as
r
w
a
■
•
■
•
•
•■ •
■ ■■
■
■
a
• M ■ ■
M■■c�tllli
Cl TR S
N •
1
■ ■ ■
1n Ma .
■
Gr
n
■i
• • as
■i'
.1
'-
`s
•
•
_
...sc:
■
a
■
• •
■
■
O
II II �
JL -
I II
� II
■sa ■ • , —� I I I
a an Q II
® ca II I • .
° II
• • a ■� II
■ A E II
f`■■ a■a■nim ■me"I ■ an ■ a I
■ ■
■
an as • til � \ ' I •
■
■
■ : ■ • e f • ••wtaeeay m
Sonoma
• • an • ■ ■ ■ sense • • • • •
■■■ � • Name • ■ ■
t` • • a■■ �• • ■ ■• ■ •g■ •• ■s ■°aftamosom •■ ■■
a ■a ■ .. ■ . .e■ ■ ■ VE • ■ ■
some .
No a
•
aa� °
■
•
I
1 •
J ■
• .....!..Lamm. .
• a
■a
a ■■
■
■II
. ■
I
■■/a
■a
■s■ ■.a
■as■■a■ an • as0
■ ■ s ■ a■msa■ a■
am a on
ao■■ ■ ■ ■
■ e ■
■ •3
■
■
m
r •a ■
■
•■
See■m
•
II
I-
a
■
m■
r
•
♦■ ■■I r
■ f
•
f
m
s
1 N
■ I �
Z e
■
/
•
■
a■
m
1 ■
■
N
■
♦ •
a-
• ■
■
■
I
■
■
•
•
■
■
anwe -ma a
E .
an ■
a
•
■
d
•
•
■
°ei s
■ ■
•
/
N . vl a -is a a
■ ■
■
• f�
■ • •
. I
an
■
•
r. ■
■■
a
■
ml p
—;7-
SAN BERNARDINO COUNTY
HYDROLOGY MANUAL
FOR
SOUTHWEST -A
AREA
2.
MR
r.M
C-1
_SA.
C-2
SERNAROLNG
7
COUNTY
J4
ME
SAN BERNARDINO COUNTY
HYDROLOGY MANUAL
INDEX MAP
P91
-D
2•t k 7" 77
"W
1 -4
D
L
Xj�
AJ
7;,
iiv
zpgf-,
-K.- Q.
7 ;.. 4e,
J
_71
xr-
a a—
B.
Ig
k4 QM
5L.
M.
hV
A,
T
1!��UR -CT 6EO OGY-'MAP
igz
t2EySWO,' SCS: SURVEY •.- •
I.
t3�
-A
IVV I
4-
A: . . . . .
A -P
j ZIT7
_J
4
A`
J..
-7
�P
u.
r
_j
R
- L
a
A
2 1,) 7. i _4
L•f7r
Nb.
r L
A jj I
j
T,
A
for,
f
N.
A.
- -=79.
:L
SOIL GROUP BOUNDARY
A SOIL GROUP DESIGNATION v SCALE 1,48,000
8OUA0ARY OF INDICATED SOURCE SCALE REDUCED BY 1/2HYDROLOGIC SOfLS GROUP MAD
C'-26
FOR
SOUTHWEST -A
AREA
C-1
_SA.
C-2
SERNAROLNG
7
COUNTY
C-4
INDEX MAP
P91
-D
2•t k 7" 77
"W
1 -4
D
L
Xj�
AJ
7;,
iiv
zpgf-,
-K.- Q.
7 ;.. 4e,
J
_71
xr-
a a—
B.
Ig
k4 QM
5L.
M.
hV
A,
T
1!��UR -CT 6EO OGY-'MAP
igz
t2EySWO,' SCS: SURVEY •.- •
I.
t3�
-A
IVV I
4-
A: . . . . .
A -P
j ZIT7
_J
4
A`
J..
-7
�P
u.
r
_j
R
- L
a
A
2 1,) 7. i _4
L•f7r
Nb.
r L
A jj I
j
T,
A
for,
f
N.
A.
- -=79.
:L
SOIL GROUP BOUNDARY
A SOIL GROUP DESIGNATION v SCALE 1,48,000
8OUA0ARY OF INDICATED SOURCE SCALE REDUCED BY 1/2HYDROLOGIC SOfLS GROUP MAD
C'-26
FIGURE C-13
FOR
SOUTHWEST -A
AREA
FIGURE C-13
11
T4N air R SW',� 1 R7W Kt)W u vv 2w Rl N.
PHELAN
H Uk
-7
-TI/ T 4
7 -
WEST SUI iMIT 1.3-
Z�-
sl
.4'
N.
7
T
4— N2.
e-�
% T
4 -2
'T I — —
ZIA,
MT SAN T-,N,o
�7'
T—
r
L. A ROWN 111
L
BtGas '41
•t,
L
N,JT w
STLINE
�,4
4-11- 1-2
+ L
p
-_T I N
T
I itt 22. t ---czl
•T w" -
AN
SAN R14ROIrO
j,
--4
J-��..--Jlll 7
J 6
INO
N D
T.
UALT
WAS.
0 TAN
is
TIS
COLTON MEN TOK
REDLANDt 1�1.. 1—
T- r 4.
J
'X7
G tom.. aElb AVE
15
z irr YUCAIPA
OAK -EN
GRANIPTERPt E
IC
w
-7 -4—
R? I
A14 ERNADl oum
-T.
ESP"
+
IVB
310E COUNI
T2S
c; ERSIDE
IRESIP.H4,..... . rlrE tion'R I
• k 071 R2w
-i I P,'dW I I
+
J.
R 5
MAC. REDUCED DRAWING
F OD 1o4TPOL�
T3S SCALE I"= 4 MILES
SAN BERNARDINO COUNTY
4A
LEGEND:
w w HYDROLOGY MANUAL
w 6 8 ISOLINES PRECIPITATION (INCHES)
*"* .............................. q
B-12
VALE EY AREA
isomYETALS
Yoo-100 YEAR U -HO
sAso ON u.SAC_ KDA&MAS 7
.ra4m EY
F
DATE WALK
1982 r -ala woo -I
FIGURE
(1)
LIMITATIONS=
Tc'
L
100
1000
90
900
80
800
70
700
60
(1)
LIMITATIONS=
I. Maximum length
x 1000 Feet
2. Maximum area x
10 Acres
600
a
50
0
H
Y
w
0
C
300
'-b
too
o
�aQ °
500
N
E v�
100
a
�
35
$
� o.
to
4Q0
a`
w
30
0
350
25
c
E,
300
c
20
19
18
250
~16
J
...
15
a
J
200
v
�-112
14
13
(1)
LIMITATIONS=
I. Maximum length
x 1000 Feet
2. Maximum area x
10 Acres
4
H
Y
w
44000
C
300
'-b
too
o
�aQ °
N
E v�
100
s o
Ce
40c
's
� o.
to
0
0
Undeveloped
Good Cover
Undeveloped
Fair Cover
Undeveloped
Poor Cover
Single Famll
(5-7 DU)
Tc
(miN;l . .
6
D
ti 7—Y
LL
8
n
e
4 N II
2 12 g
c �a
z 4 ��4 N .
c .3 15
'= 16 c
/ 17 E
18 S
�c
19. u
KEY 20 ~
L -H -Tc -K -Tc' c
F `
C
25 u
q,7 PI Development
150 9 80- Apartment
E
8 75- Mobile Home o
65- Condominium 3p
60- Single Family -5,000 ft2 Lot F
7 40- Single Family -1/4 Acre Lot
20- Single Family -1 Acre Lot 35
6 10 -Single Family- 21/2 Acre Lot
100 EXAMPLE!
40
5 (1) Lx 550, H= 5.d, K=Sing le Family (5-7 DU/Ac)
Development, Tcxl2.6 min.
4 (2) Lx 550, Hs 5.0, Kx Commercial
Development, Tcx9.'T min.
SAN BERNARDINO COUNTY TIME OF CONCENTRATION
NOMOGRAPH
HYDROLOGY MANUAL me IrnrI A 1 QI 1M A DC A
ri,,,fro n-1
Tc'
L 100
1000 90
g00 60
800 70
L.IMITATIONSi
I. Maximum length = 1000 Feet
2. Maximum area = 10 Acres
a`
H
Y » 400
300
c — too
`ca o
0
N E84" ioo
so
eo
c 40
30
tl o o. to
1
e
K P 4 0
Undevelo3
Goo veir T $ Z
Fair Covewr
- Poor
_
700
60
o
p N1
T Single amity
n
50
600
16
0
15 Commercial
(Paved),,
a
J
v
200
14
13 /
V
12
500
a
.10P1 Developmu
�
35
$
75- Mobile Ha
6 65- Condominiu
400 0`
30
7 40 - Single Fam
9--350
25
v
c
E,
300
0
L.IMITATIONSi
I. Maximum length = 1000 Feet
2. Maximum area = 10 Acres
a`
H
Y » 400
300
c — too
`ca o
0
N E84" ioo
so
eo
c 40
30
tl o o. to
1
e
K P 4 0
Undevelo3
Goo veir T $ Z
Fair Covewr
- Poor
_
1918 -
o
p N1
T Single amity
( DU/AC)
q0
16
15 Commercial
(Paved),,
a
J
v
200
14
13 /
12
.10P1 Developmu
150 E
9 60- Apartment
75- Mobile Ha
6 65- Condominiu
60- Single Fam
7 40 - Single Fam
it
Hon
m
ily-5,
lly-1/4 Acre Lat 35
20- Single Family -1 Acre Lot
6 10 -Single Family -21/2 Acre Lot
100 40
-EXAMPLE,
5 (1) L- 550', H= 5.0', K=Single Family (5-7 DU/ACI
Development, Tc=12.6 min.
4 (2) L= 550, H= 5.0, K- Commercial
Development, Tc=9.7 min.
SAN BERNARDINO COUNTY TIME OF CONCENTRATION
NOMOGRAPH
HYDROLOGY MANUAL FOR INITIAL SUBAREA
I� f% 9,
Tc
5
(min)
6
0
7 n
c '
06
8
0
/9-0
10
it
12 F
_
.4 �l4 w
c .3 `Zl 15 0
o t / 16 c
17 E
o� 18 S
i9 u
u KEY 20 ~
L -H -Tc -K -Tc' c
C]
c
25 8
U
0
30-0
000 ft 2 Lot F
c:.....e n_
me
r.
5 20
19
18
IT
16
15
`0 14
6-31
t
LIMITATIOAIS=
Tc'
L
100
1000
90
900
80
800
70
700
60
me
r.
5 20
19
18
IT
16
15
`0 14
6-31
t
LIMITATIOAIS=
I. Maximum length a 1000 Feet
a
50
2. Maximum area a 10 Acres
600
,.
0
a`
0
H
500
Y w W-400500 44000
a
0
300
33
too
$ �
0 v
N E $3 100
..
c ## — so°
Opp `0
30
SE
0
O
CL 11 o Co. to
1
�,
2 35Q b
--
me
r.
5 20
19
18
IT
16
15
`0 14
6-31
t
LIMITATIOAIS=
I. Maximum length a 1000 Feet
Tc
2. Maximum area a 10 Acres
5�
,.
(min)
a`
H
6
Y w W-400500 44000
0
300
i.
too
7
0 v
N E $3 100
..
c ## — so°
8
c
o c ,0
b 30
0
O
CL 11 o Co. to
1
�,
c .
o s
I®
L
E
K P
3�,
Undeve
p
Cover $ 2
V.. -
N
Undeveloped c 1.0
13
Fair Cover
Undeveloped
Poor Cover
O 13 /
ii
10
:a 14
w
C .3 `Zi 15
s / 16 s
I7 E
18 s
c 19 u
u KEY 20 H
L -H -Tc -K -Tc' o
w i
w v
25 v
c PI _Development
9 80- Apartment c
�:. 75- Mobile Home 30
F$ 65- Condominium E
60 - Single Family - 5,000 ft 2 Lot F
7 40 - Single Family -1/4 Acre Lot
20- Single Family -1 Acre Lot
6 10- Single Family -21/2 Acre Lot
EXAMPLE -
5 (1 j L- 550; Hz 5.0', K -Single Family (5-7 DU/Ac)
Development, Tc=12.6 min.
4 (2) Le 550, H- 5.0, K- Commercial
Development, Tc -9.T min.
SAN BERNARDINO COUNTY
HYDROLOGY MANUAL
35
40
�3 P05
Tc
( in)Tl
6 —j
M
0
7
C
8 C
0
9 C
14
15 M
e
t6 �
17 E
18-5
i9
20
0
2.5 u
0
30 e
35
ael
E
115o
r:#%.Avis, r,_.
Tc�
LIMITATIONS:
L
100
1. Maximum length x 1000 Feet
1000
90
2. Maximum area x 10 Acres
900
80
a
70
� H
v
800
r. eoo
Y w 400
60
... 300
°' ^
700
� > - too
(r
a
50
E84-
ato
o•-
o �� o so
C:
e0
I0ati
500
C to
2 e
a
0
35
D 10
..
e
e J
Opp
30
l�
Undeveloped 0 3 ~�j► -•�
Good Cover z
°
350
25
Undeveloped c 1.0
O
Fair Cover .a
300
Undeveloped
c
5
190
Poor Cover 100 0 '3
0
250
v
18
17
Single Fam
i
t6
15
Cornerciai
m(Paved)
`1r
1�F .
..
-14
90 a KEY
Q
_
13
L -H -Tc -K -Tc'
12 2�
l
o
o
to
PI Development
150
m
E
9
80- Apartment
r
75- Mobile Home
t3
65- Condominium
60 -Single Family - 5,000 ft 2 Lot
7
40- Single Family -1/4 Acre Lot
20- Single Family - i Acre Lot
6
10 -Single Family- 21/2 Acre Lot
100
EXAMPLE.,
5
(1) L- 550', H= 5.0', K=Sing le Family (5-7 DU/AC)
Development, Tc=12.6 min.
(2) L= 550, H: 5.0, K= Commercial
4
Development, Tcx9.7 min.
SAN
BERNARDINO
COUNTY
TIME OR CONCE
NOMOPRA
HYDROLOGY
MANUAL
res 11L11T1 A 1 C
Tc
( in)Tl
6 —j
M
0
7
C
8 C
0
9 C
14
15 M
e
t6 �
17 E
18-5
i9
20
0
2.5 u
0
30 e
35
ael
E
115o
r:#%.Avis, r,_.
TABLE C.2. Fm (in/hr) VALUES
FOR TYPICAL
COVER
TYPES
SOIL GROUP
COVER TYPE
Ap(1)
Q
B
C
D
NATURAL:
Barren
1.0
0.41
0.27
0.18
0.14
Row Crops (good)
1.0
0.59
0.41
0.29
0.22
Grass (fair)
1.0
0.82
0.56
0.40
0.31
Orchards (fair)
1.0
0.88
0.62
0.43
0.34
Woodland (fair)
1.0
0.95
0.69
0.50
0.40
URBAN:
Residential 0 DU/AC)
0.80
0.78
0.60
0.45
0.37
Residential (2 DU/AC)
0.70
0.68
0.53
0.39
0.32
Residential (4 DU/AC)
0.60
0.58
0.45
0.34
0.28
Residential (10 DU/AC)
0.40
0.•39
0.30
0.22
0.18
Condominium
0.35 -
0.34
0„26
0.20
0.16
Mobile Home Park
0.25
0.24
0.19
0.14
0.12
Apartments
0.20
0.19
0.15
0.11
0.09
Commercial/Industrial
0.10
0.10
0.08
0.06
0.05
NOTES:
(1) Recommended a values from Figure C-4
(2) AMC II assumed for all Fm values
(3) CN values obtained from Figure C-3
(4) DU/AC=dwelling unit per acre
C-16
When sufficient stream gauge information is available, infiltration rates for
unit hydrograph hydrology can be estimated from a study of rainfall -runoff
relationships of major storms. Where such data is not available, infiltration
rates for pervious areas as a function of CN can be estimated using Figures
C-3 and C-6. Loss rates for pervious areas estimated from the Figure C-6
curves are generally consistent with values developed from rainfall -runoff
reconstitution studies in San Bernardino County watersheds.
C.6.5. Estimation of Catchment Maximum Loss Rates F
in
The infiltration rate selected from Figure C-6 applies to the pervious
area fraction of the watershed. The infiltration rate assumed for an
impervious surface is 0.0 inch/hour. The maximum loss rate, Fm, for a
catchment is therefore given by
Fm - a p F p (C.7)
where a is the pervious area fraction, and Fp is the infiltration rate for the
pervious area.
Should a catchment contain several Fp values, the composite Fm value is
determined as a simple area average of the several Fm values. Table C.2
provides Fm values for a wide range of cover types and soil groups.
C.6.6. Design Storm Loss Rates
In design storm runoff hydrograph studies, a 244iour duration storm
pattern is used to develop the time distribution of effective rainfall over the
watershed. The effective rainfall quantities are determined by subtracting
the watershed losses from the design storm rainfall.
The loss rate used for a particular catchment is a combination of the
maximum loss rate Frn and the low loss rate F*. F* is used as the loss rate
unless F* exceeds Fm, in which case Fm is used as the loss rate. That is, Fm
serves as the maximum loss rate. Typically in 100 -year storm studies, F*
serves as the loss rate for the entire storm pattern except for the most
Fp, for the pervious area, and the effects of watershed detention. Runoff ,
coefficient curves are developed using the relationship:
0.90 (ai + (I Fp)ap), for I greater than Fp;
C: = I (D.3)
[0-90 al, for I less than or equal to Fp
where the proportion factor of 0.90 is a calibration constant determined by
an average fit between the rational method and design storm unit hydrograph
(see Section E) peak flow rate estimates, and where
C = runoff coefficient
I = . rainfall intensity (inches/hour)
Fp = infiltration rate for pervious areas (inches/hour) -
(see section C.6.4)
ai = ratio of impervious area to total area (decimal
f raction)
ap - ratio of pervious area to total area (decimal
f raction), (ap = 1 - ai)
D.6. PEAK FLOW RATE FORMULA
Combining Equations (D.l) and (D.3), the peak flow estimate for Q is
written in simpler terms by
Q = .90 (I - Fm)A (D.4)
where Fm = a p F p (see section C.6.5), and where in (D.4) it is understood that
I is greater than Fp (otherwise Q = .90 aiIA).
In (D.4), Fm represents the loss rate for the total watershed tributary to the
point of concentration. Should the tributary area cgntain several runoff
surfaces, an area -averaged Fm is calculated. Table 0.1 illustrates such an
area -averaged Fm computation.
HYDROLOGY
CALCULATIONS
PRE DEVELOP TMEN T
CERES STREET
A-1 A-2
�— 2.2 AC
a60 AC
r—
Q
Q
A-3
2.2 AC
MERRILL AVENUE
PRE -DEVELOPMENT "Q"
Area "A-1 ":
Area = 0.60 Ac
Off-site
Length = 358 ft.
H = 8 ft. [ 1222-1214 ]
Tc = 19.7 min [ FIG. D-1 ]
1 = 4.5 in./hr
Fm = 0.75
50% Urban & 50% Grass
0.5 x 0.68 + 0.5 x 0.82
Q =
0.90 ( I -Fm ) A
=
0.90 [ 4.5 — 0.75 ] 0.60
=
2.02cfs
Area "A-2":
Area = 1.10 Ac
Off-site
Length = 240 ft.
H = 7 ft. [ 1222-1215 ]
Tc = 10.5 min
1 = 4.25 in./hr
Fm = 0.41
100% Barren
Q =
0.90 ( I -Fm ) A
=
0.90[4.25-0.41 ]1.10
=
3.80 cfs
Area "A-3":
On-site
Area = 2.20 Ac
Length = 300 ft.
H = 5 ft. [ 1215-1210 ]
Tc = 11.0 min
1 = 4.1 in./hr
Fm = 0.81
40 % Urban + 30% Grass + 30% Barren
0.4 x 0.68 + 0.5 x 0.82 + 0.3 x 0.41
Q = 0.90 ( I -Fm ) A
0.90 4.1 —0.81 ]2.20
6.51 cfs
Total run-off in Pre -development condition from on-site areas.
= Area A-3
6.51 cfs
Total run-off including off-site areas.
Areas A-1 + A-2 + A-3
2.02+3.80+6.51
12.33 cfs
Total run-off contributing to Catawba Avenue.
Area A-1
2.02 cfs
Total run-off contributing to Merrill Avenue.
Areas A-2 + A-3
3.80+6.51
10.31 cfs
POST DEVELOPTMENT
CERES STREET
It i
A-1 A-2
2.2 AC
0.60 AC
r_
Q
Q
U
A-3
�- 2.2 AC
MERRILL AVENUE
POST -DEVELOPMENT "Q"
Run-off from Areas "A-1" & "A-2" remain the same. [ off-site run-off ]
Area "A-3": Area = 2.20 Ac
On-site Length = 620 ft.
H = 5.ft. [1215-1210]
Tc = 14.0 min
1 = 3.5 in./hr
Fm = 0.58 [ Table c.2 ]
100% Urban
Q = 0.90 ( I -Fm ) A
0.90[3.5-0.58]2.20
= 5.78 cfs
Total run-off in Post -development condition from on-site area.
Areas A-3
5.78 cfs
Total nun -off including off-site areas.
Areas A-1 + A-2 + A-3
2.02+3.8+5.78
11.52 cfs
Total run-off contributing to Catawba Avenue.
Areas A-1 + A-2 + A-3
2.02+3.8+5.78
11.52 cfs
In Post Development condition there is negligible run-off to Merrill Avenue.
STREET CAPACITY
CALCULATIONS
Los Angeles County Flood Control District Page c-21
ST��fT C.4PAC/TY CNIap
Y'
The S/reef Cooacify Chcrrfs D - 4/ fo D - 08 oro based'
on fh� fo/%,wing forinu/os
4!�anning� "n
Curb to curb "n " _ .015
Curb /o leliv -n " _ .O/8
"s - - sfrreef s/oae
Trl&05 u/crr Shaped Areos
iv
D
lein
Ti-apezooda/ Shaped Areas
Q 3
14,96 Si
s .
8 n
106f Oaf N
Ob - 42
"dio 1
I
ca,
f,4 1
. . . . . . . . . .
\4AJ
3X 3o
t"36I
L_6