HomeMy WebLinkAboutCDP 15-45; DRAINAGE STUDY; 2017-09-13COFFEY ENGINEERING, INC.
Drainage Study
Abdi Residence
5623 Shore Drive, Carlsbad, CA 92008
APN 210-061-1300
Project Information:
Owner: Behrooz & Sharon Abdi
18485 Withey Road
Monte Sereno, CA 95030
SEP 132017
LAND DEVELOPMENT
ENGINEERING
September 13, 2017
9666 BUEINESSPARK AVENUE, SUITE 210 SAN DIEGO, CA 92131 PHONE: (858)831-0111 Fft,x: (858)831-0179
Table of Contents
Existing Conditions........................................... 3
Proposed Project . 3
Purpose and Scope of Report............................ 3
Method of Calculations..................................... 3
Results and Conclusions................................... 4
Exemption from CWA Section 401/404........... 4
Declaration of Responsible Charge................... 5
Appendix A - Referenced Plans & Drainage Maps
Drainage Map 'A' - Existing Drainage Conditions
Drainage Map 'B' - Proposed Drainage Conditions
Appendix B - Calculations/Evaluations
Table: 100 Year Storm Flow Rate Table
Appendix C - Reference Tables & Figures (County of San Diego Hydrology Manual)
Soil Hydrology Groups
Table 3-1 —Runoff Coefficients
14
Existing Conditions
The 10,940 sqft (0.251-acre) site consists of a previously developed lot totaling 5,008 sqft of
impervious area and 2,131 sqft of pervious landscaping. The majority of the site (Basin X. 1, X.2,
X.3) drains to the Pacific Ocean through two 4" drainage lines that outlet on the gunite bluff.
Basin Z, which consists of the impervious bluff surface located above the aforementioned drainage
discharge points, sheet flows to the ocean as well. Basin Y contains a small portion of the front
yard and driveway that sheet flows to Shore Drive. See Drainage Map 'A'.
Proposed Project
Proposed is the demolish of the existing residence and hardscape, and construction of a single-
family residence. Site improvements include retaining walls, impervious surface walkways, and a
sump pump. Proposed landscaping consists of the implementation of a biofiltration basin for
stormwater treatment. The site DMAs are divided into Basins A, B, and C, which replicate the
existing flow patterns from Basin Y, X, and Z, respectively. Basin A contains the front yard and
driveway that will be untreated due to its small area and slope towards the street. Basin B consists
of the residence, paved walkways, and landscape areas that drain to the proposed 172 sqft
biofiltration basin for storm water treatment. Basin C is identical to pre-construction Basin Z in
area and flow pattern to the Ocean, and will remain undisturbed.
Purpose and Scope of Report
This report will evaluate the existing and water run-off flow patterns and flow rate characteristics
for the project site. All calculations are for a 100-year expected storm event.
Method of Calculations
The Rational Method, as defined by County of San Diego Hydrology Manual (2003), will be used
to calculate storm water flow rates. Where noted, the following calculations were used to
determine flow properties:
Rainfall Characteristics
Q = C * J * A, where
Q = Flow rate (ft'/sec)
C = Runoff coefficient
(Runoff coefficient per County of San Diego Hydrology Manual Table 3-1 reproduced in
Appendix C. Soil type D determined from the Soil Hydrologic Groups map from the County of
San Diego Hydrology Manual reproduced in Appendix C also.)
I = Rainfall intensity (in/hr.)
A = Area (acres)
Rainfall Intensity (per County of San Diego Hydrology Manual Figure 3-1 reproduced in
Appendix C)
3
= 7•44 * P6 * D °'65, where
I = Rainfall intensity (in/hr.)
P6 = Adjusted 6-hour precipitation (inches)
D = Storm duration (mm), equal to Te for time-of-concentration storms
Tc = Ti+Tt+Tp (time-of-concentration), where
Ti=Over land initial time.
TtTravel time on natural watersheds.
Tp=Travel time on drainage structures (pipes, brow ditch, gutter etc.)
Overland Time of Flow (per County of San Diego Hydrology Manual Figure 3-3 reproduced in
Appendix C)
Ti= 1.8(1.1-C) D°501( s°33 ) (Overland initial time of concentration formula), where
D= Watercourse Distance (feet)(see table 3-2 for the max. overland flow length)
s = Slope (%)
C= Runoff Coefficient
Tiinitial time of concentration (mm.)
5. Results and Conclusions:
In the existing conditions, a small portion at the front of the lot (Basin Y - 0.06 cfs) drains via
sheet flow over the top of the rolled curb along Shore drive. These flows join the public flows
within Shore Drive and travel a short distance northerly to the public storm drain system which
discharges at the base of the bluff and into the Pacific Ocean. The majority of the lot (Basin X -
0.85 cfs) is picked up by an existing area drain system that discharges though the gunite cliff face
near the base of the bluff at two locations. The remainder of the lot consists of the impervious
surface cliff face (Basin Z - 0.37 cfs) that sheet flows to the Pacific Ocean.
The proposed project replaces the existing on-site area drainage system and utilizes the existing
discharge points at the base of the bluff. The proposed system includes the addition of a
biofiltration area, which receives runoff from the majority of the site (Basin B —0.91 cfs). A sump
pump is required to direct a small portion of hardscape runoff near the rear yard staircase to the
biofiltration basin. After the runoff is treated, flows are discharged to the two existing 4" PVC
drain lines that discharge to the Pacific Ocean at the bottom of the bluff. Flows in the front yard
portion of the property (Basin A - 0.06 cfs) continue to drain over the rolled curb into Shore Drive.
The gunite bluff (Basin C - 0.37 cfs) remains undisturbed, and discharges the same flows to the
Ocean.
In total, the pre-construction flows of 1.28 cfs in the 100-year storm will increase in post-
construction conditions to 1.34 cfs as a result of increased impervious areas on the site. Discharge
to the street will remain the same at 0.06 cfs. The total runoff to the Ocean will increase, from 1.22
cfs to 1.28 cfs.
4
Exemption from CWA Section 401/404:
The project is a single-family residence, and will not propose any structure below the high tide line.
Discharges will only consist of storm water; therefore 401/404 permits are not necessary.
Declaration of Responsible Charge
I hereby declare that I am the Civil Engineer of work for this project, that I have exercised
responsibe charge over the design of the project as defined in section 6703 of the business and
professions code, and that the design is consistent with current design.
I understand that the check of project drawings and specifications by the City of Carlsbad is
confined to a review only and does not relieve me, as Engineer of Work, of my responsibilities for
project design.
Michael Kinnear Date
RCE 76785
Exp. 12-31-18
*
5
Appendix A —Reference Plans Drainage Maps
'5
K
EXISTING 6 FTAC WATER
MAIN PER PROJECT NO,
W3-17. TWO. NO. IN—AO—T\
(PROTECT IN PLACE)
V
EXISTING SEWER MAIN
IN PLACE)
EXISTING IRE HYDRANT -
(PROTECT IN PLACE)
EXISTING WATER METER AND LATERAL ' TO BE REMOVED AND REPLACED AS
NECESSARY TO COMPLY WITH CMWO
STD. DWG. W-4. )1.5 Meter) -S
INSTALL BACK FLOW DEVICE PER
CMWE DWO, NO A-4
SIGHT DISTANCE CLEARANC LINE
EXISTING STREET LIGHT MIR"CONCRETEI
PAD )PROTECT IN PLACE)
NOTE:
A RIGHT—OF—WAY PERMIT IS REOUIRED PRIOR TO ANY
WORK WITHIN THE PUBLIC RIGHT—OF—WAY.
- /77TE) JE LANOSCAP A
-'
PROPOSED STEM WALL PER / 7 / ARCHITECT'S DETAILS AS
NECESSARY
PROPOSED EQUIPMENT AREA
AND ENCLOSURE WALLS PER
ARCHITECT'S DETAILS
LANDSCAPE AREA
.G /
- PROPOSED CAD METER
LANDSCAPE 4REA 3' / EXISTING U'TLITES TO BE RELOCATED
17
S PROPOSED AIR CONDITIONER
GRITS
GAS LATERAL TO BE ' ....
TE AND REPLACED.
PROPERTY LINE
YEXISTING BRICK WALL f- 6'
)PROTECT IN PLACE)
EXIST
LANDSCAPE AREA S .'
PROPOSED WATER LINE
/ -
0 2 4 8 12 UTILITIES TO RE INSTALLED PER
THE REQUIREMENTS OF THE CITY
SCALE IN FEET
.DEPTHS F R YARD PIPING.
BURIAL / / LANDSCAPE UREA
/ SIGHT DISTANCE CLEARANCE LINE /
EXISTING TILITY PULL BOX
(PROTECT
EXISTING CONCRIETE CURB
/&D / /I:/'( -' (PROTECT IN
EXISTING SEWER MAIN / * /(-_/ EXISTING AT1LIIY POLL BOX
(PROTECT IN PLACE) '" / ".,( (PROTECT IN PLACE)
EXISTING AC PA4ENT EXISTING WALE (PROTECT
(PROTECT IN PLACE) IN PLACE)
EXISTING CON
AREA LANDSCAPE
./\
EXISTING ROLLED CURB AND GUTTER
(PROTFC.T IN P11 CF)
EXISTING,SEWER MANHOLE--,,"t
(PROTECT'IN PLACE)
C.
EXISTING WOODEN GAZEBO -'
(PROTECT IN PLACE)
EXISTING FENCE
(PROTECT IN PLACE)
IMPORTANT NOTICE
SECTON 4216 OF THE GOVERNMENT
CODE REOUIRES THAT A DIG ALERT IDENTIFICATION
NUMBER BE ISSUED BEFORE A
"PERMIT TO EXCAVATE" SILL RE VALID.
FOR YOUR DIG ALERT I.D. NUMBER CALL
UNDERGROUND SERVICE ALERT AT
B—I—I
TWO WORKING DAYS BEFORE YOU DIG
PROPOSED SEWER LINE -"
EXISTING BRICK PILASTER--'
(PROTECT IN PLACE) S
KI Cc
RXXA BUSINESSPARE AVEN
Nu. C062710
PROPOSED RESIDENCE
LOWER LEVEL FLOOR = 30.10
PAD = 29.27
S H E E I N 0
AT'
__ 30' 30'
ORATE BREAK
I
-
_—RIGHT—OF—WAY
EXISTING CONCRETE DRIVEWAY
I TO BE REMOVED
G EVIVITOR PVLI.ET CON
AND IVITEP CR151190 00000C I(PROTECT IN PLACE) )PROTECT IN PLACE)
0 I
OSED CONCRETEJ I
DRIVEWAY
EXISTING AC PAVEMENT SECTION G-G:
NOTE: (PROTECT IN PLACE) I SCALE:
BRAIN TO BE RESDESED 000CR
I WOOD SHOWER MATT I
HORIZONTAL 1 = 4'
VERTICAL I = 4'
)FFEY ENGINEERING, INC.
E. SUITE 210. DAN DIEGO, CA N2131 Ff118581831-SIl1 PAT [8581831. 5179
ENGINEER OF WORK
John S. Coffey, PC DATE DOTE OWI1OL
REGISTRATION NO. 62716 COP: 6-30-18 ENGINEER OF WORK REVISION DESCRIPTION
/ F. F. =40.10
PAD = 39.27
-
LFAS
[.ThDLEUU*tN!
T-6 SD-''
LANDSCAPE AREA
EXISTING
EXISTING RESIDENCE
LOWER LEVEL FLOOR = 30.10
RCE__ EXP.— DATE
REVIEWED BY:
INSPECTOR DATE
IT CITY OF CARLSBAD
ENGINEERING DEPARTMENT [j
FRAD
'
I—NGPLANS FOR
ABDI RESIDENCE
(52X3 SHORE DRIVE)
7—OO1X PRECISE GRADING PLAN SHEET
APPROVED: JASON S. GELDERT
CITY ENGINEER RCE 63912 EXPIRES 9/30/18 DATE I
DATE INIRAL DATE INI'fl*L 1DWN MY: __GLE PROJECT NO. DRAW /]
OTHER APPROVAL CITE OPPROVOL R BY: CDP 15 45 5018A
PROPOSED RESIDENCE
,'—'FINISH FLOOR = 00.10
A l
EXISTING WAIL (PROTECT I IN PLACE)
'AS BUILT'
I PROPOSED PUMP STATUS
PER DETAIL ON SHEET NO. 8
6.92
'HA.
PROPOSED 4 SUBDRAIH PER
DETAILS 08 SHEET NO. 9
—EXISTING LANDSCAPING r—'EXISTTNO RETAINING WALL
/ (PROTECT IN PLACE)
I 39,20 T.G.
/ INV.
_6 SD ''
- PROPOSED 4" S500RAIN PER
DETAILS ON SHEET NO. 9
PROPOSED BIOFTLTRATOH
AREA
EXISTING WALL (PROTECT
IN PLACE)
\1 ! PROPOSED SPA
DRAIN
DISCHARGE
PER SPA PLANS. \\ 57<
36.92 INV
*3 EXISTING LANDSCAPING
7 - 6 3/4 STEPS
- :
------ - -
- - --
EXISTING WALL
(PROTECT IN PLACE). -
I /
EXISTING
-.--
- - !L- LANDSCAPING__-\
I
-. -' PROPDED / .- B1P1LTRATION
AREA
- -
-
- -
-6
-
E000HG WOOL
(PROTECT IN LACE) \
- - _\ \
\ -' .3697IVE1,'(\ \_
lNJVt
11 GRACE 13REAK
12
Q ' -
QJL -" ---- . - -- - ---------------- --
SCALE IN FEET
"AS BUILT"
DRAINAGE DETAIL:
SCALE: 1" = U'
3920 T.G.
34.31 INV.
Uu
w
cn
0 1,5 3 6 9
SCALE IN FEET IMPORTANT NOTICE
SECTION 4216 OF THE GOVERNMENT
CODE REQUIRES THAT A DIG ALERT IDENTIFICATION
NUMBER BE ISSUED BEFORE A
PERMIT TO EXCAVATE' WILL BE VALID.
FOR YOUR DIG ALERT I.D. NUMBER CALL
UNDERGROUND SERVICE ALERT AT
B—i—i
TWO WORKING DAYS BEFORE YOU DIG
ME cc
9666 BUSINESSPARK AVON
CAL
)FFEY ENGINEERING, INC.
IE, SUITE 210, SAN DIEGO, CA 92131 PH (858)831- Sill FAX(B58)B31-0179
ENGINEER OF WORK
John S. Coffey. FE DATE DATE INI1AL
REGISTRATION NO. 62716 EXP: 6-30-18 ENGINEER OF WORK REVISION DESCRIPTION
RCE... EXP._________ DATE
REVIEWED BY:
INSPECTOR DATE
CITY OF CARLSBAD SAEETS
12 ENGINEERING DEPARTMENT
GRADING PLANS FOR:
ASDI RESIDENCE
- (5263 SHORE DRIVE)
GR2017-0010 PRECISE GRADING PLAN SHEET [APPROVED JASON S. GELDERT
(CITY ENGINEER RCE 63912 EXPIRES 9/30/18 DATE
DATE INITIAL DATE I INMAL CI-IKD BY:
DWN BY:
_0C__I
PROJECT NO. [KING NO.
OTHER APPROVAL CITY APPROVAL RVWD BY: CDP 15-45 501-8A
IMPORTANT NOTICE
SECTION 4216 OF THE GOVERNMENT
CODE REQUIRES THAT A DIG ALERT IDENTIFICATION
NUMBER BE ISSUED BEFORE A
"PERMIT TO EXCAVATE" WILL BE VALID.
FOR YOUR DIG ALERT I.D. NUMBER CALL
UNDERGROUND SERVICE ALERT AT
8-1-1
TWO WORKING DAYS BEFORE YOU DIG
HS: c c
RAAN BUSINDSOPARK AVER
No C062716
FFEY ENGINEERING, INC.
D. SUITE 210, DAN DIEGO, CA92I3I PH(858)831-0111 FAX(858)831-0179
SHEET
6 CITY OF CARLSff.A171 SHEETS
DNGINEERINGDEPARTMENT 12
GRADING PLANS FOR
ABDI RESIDENCE
~GR2017-0010
(5263 SHONE DRIVE)
PRECISE GRADING PLAN SHEET
APPROVED JASON S. GELDERT
CITY ENGINEER RCE 63912 EXPIRES 9/30/18 DATE
OWN B'G .......O/L.., PROJECT NO. DRAPING NO. CHKD BY RW1O BY,,,,,,,,,,,,,,,, COP 15-45 501-SA
ENGINEER OF WORK
John S. Coffey, FE DATE I_OATH I INITlAL I I EASE 1011100 RATE INITiAL
REGISTRATION NO. 62716 EXP 6-30-18 ENGINEER OF WORKI REVISION DESCRIPTION OTHER WPROVAL CITY APPROVAL
4
A
PROPOSED RESIDENCE
LOWER LEVEL FLOOR = 30.10
PAD = 29.27
N.O.
44, r 4/ - LOWER LEVEL FLOOR = 28.85
PAD = 27.94
0 PROPOSED RETAINING
WALL PER DETAIL ON
SHEET NO. 11-
40.60 T.W.
H 35931.F,
PROPOSED SEWER SUMP POMP
PER BUILDING PLANS
C
&. 0'
EXISTING FENCE
#
(PROTECT
EXISTING BRICK BRICK PATS
\S
(PROTECT NO
SCALE IN FEET
EXISTING CONCRETE WALK
PROPOSED CONCRETE PAVING TO BE REMOVED
PER LANDSCAPE ARCHITECT'S ""\\
DETAILS.
PROPOSES STORM BRAIN 40.60
T.N.
/t
PROPOSED SUBORAIN PER OPOSED GROUND LEVEL
STRUCTURAL ENGINEERS 40.10
DETAILS. SEE SHEETNO
35.03
EXISTING GRADE-' '.4. PERMANENT SACRED WALL
PER BUILDING PERMIT
PROPOSED LONER LEVEL PROPOSED SEWER PER FLOOR = 30.10 PLUMBING ENGINEER'S
PLANS.
PROPOSED RETAINING WALL
PER STRUCTURAL ENGINEER'S
DETAILS. SEE DETAIL R.T4
I ON SWEET NO. 12.
SECTION H-H:
SCALE
HORIZONTAL: 1" = B'
VERTICAL: 1" = 8'
7---" -;- -- -. /I
3 PIPE BEYOND CLEANOUT]
TO BE REMOVE
I.E. /__7 1BoLD BROOKS CLEANOUT CUNiEAUiXX LOCATE EXISTING
STORM GRAIN PIPE. -RIM 35.8
IE_3.0 (2 PIPES OUT
(PROTE IN PLACE)
OOEXR TO
VERIC(f EXISTING FENCE
5-.--...
(PROTECT IN PLACE)
EXISTING STORM DRAIN
UONTRACTOR TO VERIFY LOCATION AS NECESSARY
(PROTECT IN PLACE)
"-EXISTING CONC. WALKWAY . /----------------
(I.E. =
N '2
_(
- - - /
/ --------------------------
-
.I 'AS BUILT
i. 7/ 7 - -
- --'-I /
.
RCE EXP.- DATE ------------------------------------------------------------
. -
____
REVIEWED BY
INSPECTOR DATE
----.
'ROSEX SEWER LINES
7-
S
RETAINED EDGE PER #VV!
\\'
/PIPE N
TO BE..REIVOVED
DAYLIGHT LINE-" ..3IDSID
EXISTING FENCE
(PROTECT IN PLACE) - ..."RIDGE
EXISTNG RAISED WOOD PATIO
(PROTECT IN PLACE)
-CONTRACTOR TX LATE EOISTNG
STORM DRAB PIPE. --
--
--
-- EXISTING STORM ORAIN
CONTRACTOR TO ERIFY,...--"
--[SEASON AS4ECESSARO
TO MAKE161NT (PROTECT ------
JNLACE)
DRAINAGE MANAGEMENT AREA (DMA) EXHIBIT
EXISTING CONDITIONS LECEND:
E)STING CONTOUR
- - BAJIN LIMITS
ORE
U
A
\.... BASIN Y . 0. 0 13 AC. x
2
0.111 A1%
IMPERVIOUS AREA
(5648 S
AT
\
SI TE CHARACTERI STI CS:
HYDROLOGIC SOIL GROUP...........B
BASIN X.2 ',
\\.
0,052 AC.
APPROXIMATE DEPTH TO GROUND WATER ........... > 20 FEET
I BASIN X3 CRITICAL COURSE SEDIMENT YIELD AREAS_ ........ NONE
f 0.011 AC.
1'
DMA ID ii..
\BASIN A - I
XX.XX AC BASIN
.011 AC.
7___'y•_ J -EXISTING 4" CONCRETE U STORM DRAIN
0 10 20 40 60
SCALE IN FEET
COFFEY ENGINEERING, INC.
15-084
?
0 10 20 40 60
SCALE IN FEET
DRAINAGE MANAGEMENT AREA (DMA) EXHIBIT
PROPOSED CONDITIONS
LEDE ND:
EXISTING CONTOUR
- - - BASIN LIMITS
PVC DRAIN LINE & 0 LANDSCAPE DRAINS
PERVIOUS AREA
\j (1,811 S.F.)
IMPERVIOUS AREA
(6,396 S.F.)
BIOFILTRATION AREA
I,. (172 S.F.)
SITE CHARACTERISTICS:
HYDROLOGIC SOIL GROUP ..... ......B
APPROXIMATE DEPTH TO GROUND WATER...........> 20 FEET
CRITICAL COURSE SEDIMENT YIELD AREAS...........NONE
DMA ID BASIN AREA (AC.) DMA TYPE
RASIN A 0.01.3 SF1 F-MITIGATING
BASIN B 0.174
0.063
BIOFILTRATION
BASIN C N/A
15-084
Appendix B —Calculation/Evaluations
100 Year Storm
Table B - Pre Construction Flow Conditions
Summary
Flow ID (Basin)
Runoff
Coefficient,
C
(5 min minimum)
Total time-of-
concentration, TC
(mm)
Rainfall
Intensity, I
(in/hr)
Basin
Area, A
(acres) Q (cfs) Flow ID (Basin) Flow Description
X.1 0.71 5.00 6.59 0.111 0.52 V Drains to Ocean
X.2 0.80 5.00 6.59 0.053 0.28 X.2 Drains to Ocean
X.3 0.67 5.00 6.59 0.012 0.05 X.3 Drains to Ocean
yj 0.691 5.001 6.591 0.0131 0.06 V I Sheet flow to Street
ZI 0.901 5.001 6.591 0.0631 0.37 z I Sheet flow to Ocean
Sum= 1.28
Table B - Post Construction Flow Conditions Table B - Hydraulics of Proposed Structures
Summary
Flow ID (Basin)
Runoff
Coefficient,
C
(5 min minimum)
Total time-of-
concentration, Tc
(mm)
Rainfall
Intensity, I
(in/hr)
Basin
Area, A
(acres) Q (cfs) Flow ID (Basin) Flow Description
A 0.711 5.001 6.591 0.0137-0.06 A Sheet flow to Street
B 0.79 5.00 6.59 0.175 0.91 B Discharges to Biofiltration
C 0.901 5.00 6.591 0.0631 0.37 C Sheet flow to Ocean
Sum= 1.34
DMA Tabulations
Basin Permeable
Area
Impermeable
Area Area (ft) Area 'C' Value (Acres) Flow Pattern
X.1 1720 3132 4,852 0.111 0.71 Drains to Ocean
X.2 411 1876 2,287 0.053 0.80 Drains to Ocean
X.3 213 292 505 0.012 0.67 Drains to Ocean
Y 217 343 560 0.013 0.69 Sheet flow to Street
Z 0 2736 2,736 0.063 0.90 Sheet flow to Ocean
Total 2131 5008 10,940 0.251
Basin Permeable
Area
Impermeable
Area Area (ft) Area 'C' Value (Acres) Flow Pattern
A 196 365 561 0.013 0.71 Drains to Street
B 1552 6084 7,636 0.175 0.79 Discharges to Biofiltration
C 0 2743 2,7431 0.0631 0.90 Sheet flow to Ocean
Total 1748 91921 10,9401 0.251
Runoff Coefficient
'C' I
IPermeable Tlmpermeable
0.351 0.901
PIPE FLOW PROGRAM DATE: 09-13-2017
TIME: 21:34:15
(1) Diaetei- (Lic1e) 4. (2) Itarinings ii .010
(3) slope (fr/P) ........6000 () t (cfs) 1.92
(5) depth (Pt) ..........0.33 (.6) cpth/Diavitc.i- 1.00
Uelocit9 (f) ......21.95 Ueiocit . 7.48
Area (sq. Ft.) 0.09
Crit ical Duch ......0.33 Critical Slope . . - 0.5952
Cr i Ic al U lo c ii y .. 21.95 Fto ude ;4ui thei N/A
from
v Characteristics
biofiltration
of Existing 4"
basin is halved
PVC Outlet Pipe on Bluff @
as flows feed into two outlet
Approximately 60% Slope
pipes)
(Overall 'QL,-V
PIPE FLOW PROGRAM DATE: 09-13-2017
TIME: 21:40:57
(I) 1iatettr 4. (2) hairiirgs is .010
() slop (P/IL) .6000 (cf) 0.46
(5) tCpLh ................0.11 (6) c1:pu /Diaetr . 0.33
Ue1ociL9 '. p) , 17.99 .Iocit, Nac' 5.03
re (Sq. .) 0.03
Critiec4J 3.ii:li ......0.33 Critical Slope 0.0301
Critical Uelocit,., 5.25 P1'oLth Iii 11.17
Appendix C —Reference Tables & Figures
(County of San Diego Hydrology Manual)
San Diego County Hydrology Manual Section: 3 Date: June 2003 Page: 6of26
Table 3-1
RUNOFF COEFFICIENTS FOR URBAN AREAS
Land Use I Runoff Coefficient "C"
Soil Type
NRCS Elements County Elements % IMPER A B C D
Undisturbed Natural Terrain (Natural)
Low Density Residential (LDR)
Low Density Residential (LDR)
Low Density Residential (LDR)
Medium Density Residential (MDR)
Medium Density Residential (MDR)
Medium Density Residential (MDR)
Medium Density Residential (MDR)
High Density Residential (HDR)
High Density Residential (I{DR)
Commercial/Industrial (N. Corn)
Commercial/Industrial (G. Corn)
Commercial/Industrial (O.P. Corn)
Commercial/Industrial (Limited I.)
Commercial/Industrial (General I.)
Permanent Open Space 0* 0.20 0.25 0.30 0.35
Residential, l.O DU/A orless 10 0.27 0.32 0.36 0.41
Residential, 2.0 DU/A or less 20 0.34 0.38 0.42 0.46
Residential, 2.9 DU/A or less 25 0.38 0.41 0.45 0.49
Residential, 4.3 DU/A or less 30 0.41 0.45 0.48 0.52
Residential, 7.3 DU/A or less 40 0.48 0.51 0.54 0.57
Residential, 10.9 DU/A or less 45 0.52 0.54 0.57 0.60
Residential, 14.5 DU/A or less 50 0.55 0.58 0.60 0.63
Residential, 24.0 DU/A or less 65 0.66 0.67 0.69 0.71
Residential, 43.0 DU/A or less 80 0.76 0.77 0.78 0.79
Neighborhood Commercial 80 0.76 0.77 0.78 0.79
General Commercial 85 0.80 0.80 0.81 0.82
Office Professional/Commercial 90 0.83 0.84 0.84 0.85
Limited Industrial 90 0.83 0.84 0.84 0.85
General Industrial 95 0.87 0.87 0.87 0.87
*The values associated with 0% impervious may be used for direct calculation of the runoff coefficient as described in Section 3.1.2 (representing the pervious runoff
coefficient, Cp, for the soil type), or for areas that will remain undisturbed in perpetuity. Justification must be given that the area will remain natural forever (e.g., the area
is located in Cleveland National Forest).
DU/A dwelling units per acre
NRCS = National Resources Conservation Service
3-6
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