HomeMy WebLinkAboutCT 04-14A; TRAILS END; DRAINAGE STUDY; 2014-10-01ECORD COPY
Date
--
e-r04- lt+A-
mm
Trails End
CT 0444A
CITY OF CARLSBAD - CALIFORNIA
October, 2014
PREPARED FOR:
Pacifica Enterprises, Inc.
5505 Cancha De Golf
Rancho Santa Fe, CA 92091
Phone: 858-755-0216
ASSESSOR'S PARCEL NUMBERS: 156-090-41-00
PREPARED BY:
AA
MASSON
& ASSOCIATES, INC.
PLANNING ENGINEERING A SURVEYING
200 E. Washington Ave., Suite 200
Escondido, CA 92025
P. 760.741.3570
F. 760.741.1786
www.masson-assoc.com
;c:Th
JAN09 2015
• a:
No. CO3221.7 1
1115
DRAINAGE STUDY - TRAILS END CARLSBAD
TABLE OF CONTENTS:
INTRODUCTION - Page 3
DISCUSSION & CALCULATION - Page 3 to Page 7
CONCLUSION - Page 8
EXHIBIT 1- VICINITY MAP
EXHIBIT 2 - SOIL HYDROLOGIC GROUP MAP
EXHIBIT 3-100 YEAR —6 HOUR RAINFALL ISOPLU VIALS
EXHIBIT 4-100 YEAR —24 HOUR RAINFALL ISOPLUVIALS
EXHIBIT 5- RUNOFF COEFFICIENTS FORIJRBAN AREAS (Table 3-1)
EXHIBIT 6- GUTTER & ROADWAY DISCHARGE VELOCITY CHART (fig. 3-6)
EXHIBIT 7- PRE-DEVELOPED DRAINAGE AREA
EXHIBIT 8- POST-DEVELOPED DRAINAGE AREA (Sub-basins)
I
I
Introduction
The site is located at the northwestern corner of the intersection of Carlsbad Village Drive and
U
Donna Drive.
This study covers the proposed development of 7 twin homes (14 units) located on 2.79 acres of
land, of which, approximately 0.5 Acres will be quitclaimed and become a part of Donna Drive I right-of-way.
This study will analyze the difference in the pre-developed and the post-developed stormwater I discharge from the site, including detention calculations.
I A Storm Water Management Plan will be undertaken to indicate how the first flush flow, (Qwq),
will be filtered before leaving the site, and we will also show how the 100 year storm (Q 100) will
be accommodated.
I Discussion and Calculation
I The analysis was performed in conjunction with the June 2003 San Diego County Hydrology
Manual (SDCHM). Unless otherwise indicated, all calculation worksheets are from the
appendices of the SDCHM.
I The Hydrological Soils Map indicates that the site is located in an area marked MIE which is
"Marina loamy course sand" 9 to 30% slopes. The onsite soils are considered to fall into
I Hydrologic Soils Group (HSG) "D". The runoff from this soil type is medium to rapid, and the
erosion hazard moderate to high.
I The precipitations were obtained from the 100 year rainfall isopluvials for the 6 hour and 24 hour
storm events, as follows (Exhibit 4 and 5):
I P(6)=2.8 in
P(24)=4.7 in
I The County of San Diego Hydrology Manual Table 3-1, "Runoff Coefficients for Urban Areas"
(Exhibit 7), indicates a runoff co-efficient of:
I C = 0.35 : Undisturbed Natural Terrain (natural) and Developed/Landscaped Areas;
C = 0.57 (minimum).: Developed Condition (Medium Density Residential-7.3 DU/A or less),
I
applied to the residential lots;
The rational method Q = CIA will be applied to determine the stormwater discharge for each of
the drainage basins.
I
I
[1
I
Pre-Developed condition:
(See Exhibit 7)
This is an "Infihl Project" and does not receive storm drain flow from surrounding off-site areas.
Flow beyond the northern property line is intercepted by an existing concrete lined brow ditch
(offsite), and discharges onto Hosp Way on the western side of the property.
Donna Drive and Carlsbad Village Drive on the east side of the property prevent ingress of off-
site stormwater on the site.
The slope of the off-site terrain on the west and south side of the property currently drains the
flow away from the proposed development in a westerly direction.
Currently, all of the 2.79 Acres of the site (Basin I) sheet flows in a westerly direction, onto an
undeveloped Open Space lot planted with eucalyptus trees, and onto Hosp Way, where it is
intercepted by the City drainage system.
Basin I
(Time of Concentration Calculation per the SDCHM)
Tc =T1 +Tt where:
Ti = Time of Concentration for an initial area of 100' in length where sheet-flow occurs.
Ti = 1.8 (1.1-C) '[b
3 -.
C = Runoff Coefficient = 0.35
D = Water Course Length = 100 ft
S = 16% (natural ground average slope)
Ti =1.8 (1.1-0.35) 'I 100
Ti = 5.4 minutes
= Time of Travel through natural channel in minutes.
T = (11.9 L3)°385 x 60
AE
L = Distance of watercourse in miles.
AE = Change in elevation along effective slope in feet.
U
I El.
I
I
I
I
I
I
I
I
I
Tt = (11.9 x (120/5280)°385x 60
I (220-185)
T=O.5 min
I Therefore:
U Tc=Ti+T
T = 5.9 mins
Calculation the SDCHM) (Intensity per
I
ID = Duration Tc
P6 = 2.8
1=6.66
TARTY 1: Oinn Calculation of the Pre-Develoned Situation
Drainage
Basin
Average
Slope
Tc
Minutes
Runoff
Coefficient
Intensity
Inches/hr
Area
Acres Qioo
I 16.0% 5.9 0.35 6.66 2.79 6.5cfs
Total Flow
Qioo 6.5 ci s
Post-developed situation Tables 2 & 3
(See Exhibit 8)
Basin A is mainly composed of landscape areas sheet flow north where it is intercepted by a
drainage ditch located alongside the north perimeter of the site which carries the flow west and
releases it through a series of pipes matching the pre-development flow conditions.
Basin B (Lots 10-14) collect storm water using grass swales and into area drain inlets which
convey the flow through drainage pipes and discharged into the GrassPave2 area in Lot 17 which
serves as a water quality treatment area. The GrassPave2 area is sloped toward the bioretention
basin to allow positive drainage during greater storm events.
Basin C (Lots 1-6) collect storm water using grass swales which flow into area drain inlets which
convey the collected flows through drainage pipes and discharging at the gutter flow line of the
I
pervious roadway in the cul-de-sac. Basin G (Lots and 7- 9) collect storm water using grass
swales then direct the flow to area drain inlets which convey the collected flow directly to the
proposed bioretention basin on lot 17.
I
I
I
[1
I
I
I
I
I
1
~
C
Basin D (Lot 15 -Community Area) is a grass-covered lot sloped southerly toward a retaining
wall with weep holes which provide hydraulic relief from storm water run-off; The storm water
run-off from the weep holes discharge onto the pervious pavement and flows across the roadway
and intercepted by the bioretention basin located on lot 17.
Basin E (Lot 16) collects the storm water via street gutters that discharge onto Basin F (the
proposed maintenance access driveway) which discharges directly to the bioretention basin in lot
17.
Lot 17 hosts the GrassPave2 and the bioretention basin. Flows from all lot areas ( except Lot A)
end up in the bioretention basin which is designed to detain the 100 year event flow. The
underground underground storage in gravel is designed to address the post construction flow by
retaining and releasing it at pre-development flow rates (see Storm Water Management Plan).
Flows greater than the 100 year storm events will be released by an emergency spillway located
above the 100 year level.
Calculations:
Due to the limited travel distance of each Basin, we will adopt a Tc of 5 minutes in all post
development cases ( conservative approach).
antensity Calculation per the SDCHM)
D =Duration = Tc = 5 minutes
P6= 2.8
1=7.38
TABLE 2: Q1oo Calculation of the Post-Developed Situation
(fl.ow intercepted by Brow Ditch)
Drainage Average Tc Runoff Intensity Area Q100
Basin Slope Minutes Coefficient Inches/hr Acres
A 50% *(2.9) 5.0 0.35 7.38 0.28 0.7 cfs
Total Flow Q100 0.7 cfs
This sub-basin generate a total discharge of 0. 7 cfs and flows to the site's westerly boundary, being
dissip_ated along the property line by a proposed concrete brow ditch, functioning as a weir (matching the
existing pre-developed flow pattern). This brow ditch will have 0.5% slope towards 3" dia PVC outlets
pipes with a capacity to discharge 0.23 cfs, the outlet openings will be placed at every 25 ft and at the low
spot to avoid ponding during small events.
TABLE 2a: Q1oo Calculation of the Post-Developed Situation
(flow directed to Donna Drive by Standard Street Improvements)
6
C
C
C
r -
Drainage Average Tc Runoff Intensity Area Q100
Basin Slope Minutes Coefficient Inches/hr Acres
Street 2% *5.0 0.60 7.38 0.06 0.3 cfs
Total Flow Q100 ,;
0.3 cfs
This sub-basin generate a total discharge of 0. 7 cfs and flows to the site's westerly boundary, being
dissipated along the property line by a proposed concrete brow ditch, functioning as a weir (matching the
existing pre-developed flow pattern). This brow ditch will have 0.5% slope towards 3" dia PVC outlets
pipes with a capacity to discharge 0.23 cfs, the outlet openings will be placed at every 25 ft and at the low
spot to avoid ponding during small events.
TABLE 3: Q100 Calculation of the Post-Developed Situation
(flow intercepted by retention basin)
Drainage Average Tc Runoff Intensity Area Q100
Basin Slope Minutes Coefficient Inches/hr Acres
B 19% *(5.2) 5.0 0.60 7.38 0.59 2.6 cfs
C 21% *(5.2) 5.0 0.57 7.38 0.71 3.0 cfs
D 25% *(3.6) 5.0 0.35 7.38 0.07 0.2 cfs
E 15% *(2.2) 5.0 0.63 7.38 0.47 2.2 cfs
F 19% *(5.2) 5.0 0.35 7.38 0.31 0.8 cfs
G 19% *(5.2) 5.0 0.60 7.38 0.30 1.3 cfs
Total Combined
Flows to
Q100 of Basins B thru G 10.1 cfs
Retention Basin
Sub-Basins B thru G generate a total discharge of 10.1 cfs and flows to the site's southwesterly
boundary to a proposed bioretention basin.
*(3.6) = calculated Tc, 5.0 = Adopted Tc
Bioretention Basin -0100 Detention:
(See Exhibit 11)
City regulations require that the post-developed Q1oo discharge rate may not exceed the pre-developed
Q100 flow rate.
In the Q100 post developed situation, we previously indicated that the discharge from Basins A, will
flow off-site without passing through the bioretention basin at a rate lower than the pre-developed flow
patterns.
In the Q100 post developed situation, we previously indicated that the discharge from Basins B-G will
flow to the detention basin at a rate greater than the pre-developed situation.
7
I
I
I
I
I
I
1
I
I
I
I
We will use these figures to calculate the required capacity of the detention basin and outflow pipe.
Detainment Volume Calculations - See pages 10 - 12
For storm events greater than the 100-Year Event, an emergency overflow spillway will be
installed above the 100 year storm water level and routed to the proposed rip-rap pad; the
spillway will have a discharge capacity of 10.63 cfs.
Emergency Spillway Calculations:
Length over weir crest (L) = 3.5 ft
Head above weir crest (H) = 1.0 ft
Crest breadth = 7.0 ft
Broad crested weir coefficient (C) = 3.04
Q C x L x HA(3/2)
Q= 10.63 cfs
Peak Flow Attenuation:
Storm runoff from the development and roadways are directed into proposed drain inlets which
convey flows to the bio-retention basin. The bioretention basin is designed to provide water quality
treatment for the site. The basin also provides flow-control. Outflow, from the bioretention basin will
flow into a drainage structure that controls outflows.
Street Flow:
I
I
The depth of flow in the gutter on the access road was calculated using the Gutter & Roadway
Discharge - Velocity Chart - Exhibit 6 (Figure 3-6).
The total flow generated by the street having a maximum slope of 15%, creating a curb flow depth of
almost 0.22 ft. The total flow generated by the cul-de-sac having a maximum slope of 3%, creating a
curb flow depth of 0.28 ft. The back of sidewalk / beginning of driveway will then be 0.7 ft higher
I during a Qioo storm event for driveways with a concrete gutter in front.
Type G Catch Basin Capacity:
The capacity of the Type G Catch Basin collecting runoff from Area E is determined using the orifice
equation: Q=CA*(2gh)I'.5.
We will assume that the net actual-area of the grate is about 1/3 of the gross area, to allow for the area
of the grate members and partial clogging.
Therefore Q = 0.6 * 3' * 1.67' *0.33 * (2 * 32.2 * 0.5')".5 = 5.6 cfs. Since this is much greater than
the runoff from the area, this catch basin is adequate.
1 8
Conclusion:
We have determined the pre- & post-developed Qioo flows, and indicated how the increased runoff
will be controlled and detained on the site. By having the proposed brow ditch working as a weir along
the length of the western property line, the flow will discharge in a similar manner to the pre-
developed situation, and also control the discharge rate so as not to exceed the pre-developed Qioo
discharge rate. The bioretention basin will detain and release the 100 year event flow at a rate that is
less than the pre-development flow rate.
I
I
I
I
I
I
I
I
I
I
I
E
I 9
I
TABLE 4: Summary Table
I
I
Basin Pre-
Dis
A
B-G
Totals
development
charge Qioo
Post-development
now Qioo
Post-development
discharge Qioo
n.a. 0.7 cfs 0.69 cfs
n.a. 10.1 cfs 5.8 cfs
6.5 cfs 10.8 cfs 6 fs
We have also shown that the proposed onsite drainage systems have sufficient capacity to convey the
100-year storm event.
I
Bio-Retention Basin
I Stage - Storage - Discharge Calculations
I
An approximate analysis was performed using the 100 year, 6 hour storm hydrograph to
determine basin inflow.
I
The outflow is controlled at three stages:
. Below an elevation of 191.5, the outflow is controlled by the size of the pipe draining
from the French drain collector to the outlet control structure.
I
. Above an elevation of 191.5, the outflow is controlled by the size of the grate in the lid of
the outlet structure (24 x 24 inches), together with the outflow from the French drain.
The available storage volume is determined based on the design contours.
Elev. Area Depth Volume
Cum.
Volume Discharge Discharge Calculation Method
sf ft cfs
191 0 0
0 to 0.52
Elevation Range: 191 to 191.5.
Rate is based on rate of discharge through
the 6" pipe used in the collection system for
the perforated drains - Manning's equation. 191.5 720 0.5 180 180
192 1080 1 450 1 630
.52 to 4.95
1
Elevation Range: 191.5 to 193.0
Rate is based on rate of discharge through
the 18" x 18" grate on the top of the catch
basin. Used weir or orifice equation,
depending on depth of water over the grate.
192.5 1650 1.5 683 1313
193 1 2905 1 2 1 1139 2451
I
Graphs of Depth, Inflow, Outflow and Storage Volume versus Time are shown below.
10
The graphs indicate:
The maximum water elevation is 192.6.
The maximum storage volume is 1479 cf.
The maximum inflow is 10.1 cfs (for the 6 hour hydrograph).
The maximum outflow is 5.0 cfs.
Therefore, the total outflow from the site is 5.0 cfs, plus 0.7 cfs from Area A, plus 0.3 from
Donna Drive = 6.0 cfs. This is slightly lower than the pre-development flow of 6.5 cfs from the
overall site.
The drawdown time for this basin is slightly over 2 hours. The drawdown begins at slightly after
4 hours into the 6 hour storm and ends at about 6 hours and 15 minutes.
11
Inflow hydrograph is based on the methodology described in Section 6 of the San Diego County
Hydrology Manual (as illustrated by Figure 6-2 of the manual). The peak rainfall distribution has
a peak flow based on the peak intensity calculated by the Rational Method. The amount of flow
(Volume) during the peak period is: V=CIA x peak time period.
12
1
I
j
I
I
I EXHIBIT 1- VICINITY MAP
I
I
I
I
I
I
I
F~
I
1
I
I
I
I
1 S 14
TRAILS END DEVELOPMENT
THE CITY OF CARLSBAD, CALIFORNIA
CITY OF OCEANSIDE
NOT
SCALO
CITY OF VISTA
CITY OF SAN MARCOS
CITY OF ENCINITAS
\'ICINITY MAP
Scale: N.T.S.
I
I
I
I EXHIBIT 2- SOIL HYDROLOGIC GROUP MAP
I
I
I
L
I
I
I
I
I
I
I
I
I
1 15
117°30'0'W 117°15'0'W 117°0'0"W 116°45'0-W 116°30'0-W 116°15'0'W z
~jtJ Qran~
M
~ ~· · Jafiiil I ilE · 11 · · · 1 I I ' · · t I ' ~ 111 · ... I ; . : . 11 · , .. 1 · .. : , . ! •• 111 · : . E ... 11 · ... 1 · .. ! 1 · ... I ' .. H
[L ! I I~
~tN t L 111 ~.
~
z ~ I() ...
i1
z 1 ·
~. l 111 . f j j j ~0~~ BFActAW u~.,~·wr-i , .,,,. • 1 1 rlJLI , . 1 1 1 1 1 -r~ ..-----. J ..,-V . ~ . , O
:.i M
~
:,
I
~TI 1 11111 1 1 F . If . I e.g r-~-i-~~4-l--_:_~~z ~ .--~~r-~~+-+-~~--1..v ~
117'30'0"W 117"15'0"W 111·o·O"W 116°45'0"W 116'30'0"W 116" 15'0'W
County of San Diego
Hydrology Manual
Soil Hydrologic Group
N
Legend h
-Major Roads
~ Incorporated City Bdy
HYDROLOGIC SOIL GROUP
Hydrologlc Group Undefined
•Hydrologic Group A
Hydrologlc Group B
Hydrologic Group C
• Hydrologic Group D
n No Soil Data
Note: Soil Data Source
USDA/NRCS
SSURGO Soils 2007
A ,--I -I
31.50 3 Miles
• .
DPW *GIS .. _ _. ......... -.. ,... '"""'-~--:ir, ......
~GJS
THIS MAP IS PROVIOED WITHOUT WAARANTY OF AN'f KJr,,o,
EITHER EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED
TO, THE IMPLIED WARRANTIES OF MERCHANTABlll'TY Ml)
FITNESS FOR A PARTICUlAR PURPOSE.
Coptright SanGIS. AJ Rlg,ts Reserwd.
This product may ccn181n lnfcrmsllon !ram the SANDAG Regional
Information System whleh c:annot bo roproduced without the wrtttan
pa-msslon of SANDAG.
This produc:I maycmta'n Information 'o\'hlch has been reprocix:ed
wtth permission granted 'a'/ Thoma• Brathenl Maps.
U
U
U
U EXHIBIT 3-100 YEAR -6 HOUR RAINFALL ISOPLUVIALS
U
U
U
I
U
I
U
U
I
U
U
U
U
U
U 16
I
I
I
I
l i
b C • ..... 11 I~.
I I
[T~
111 ~ . ..T ..-
.l
~1r
op1 .
ill!= 111 !IE r 1 1 1 I , _::_
' ,._ I " J -II " f++ I I "
o~~e · -~-~ it ·-· -I . i=====~i~~==~~~~lt'~~==~~ B<l'-++~ ,-.-,~ I .-.tic":-:' I,, . I -t 1 J
--+-+--~O~n .. , -··: ,,( /°:"-~, ~iverside Coun r .. ... .... .,,. , j • ·:·";. ··,
I cg
*' ,r---+--+--
1
LI
I -IT I
I
I
. . ~· . cl -~ ---... . • ., •• •• • • •. ,' . ~ . . . .. \ , ·-. •.. .. ·. .. . .. . . •, ' '
. I
••. ~--I 1 '-. ----.-~ ... _ ~ L '\ \
I . -,;-~
i .
~L I !
; . : .... · 1 ·. ~--· .. ·· ~·-I I •••• • .. __ '. '• •• •• ••• • ...... : ·,. !/.. • •• _: : ' I
,·~-•.. ·-.• -,. ·· ·-~~-~t~r·::·:~==-~-~~-M!~d·~-=~-~~~-~~-~·~·~Q~~~~·~~~~~~ L,1 J. d 1 ..J • •. -· • .-' r -· -· .. • -·· .... · , . ..J I i. , •• • · • • • ·.": • <. ··. ·.• •. '. t: ~ : ., • -, • • , . , ... , . . -.. . , . .• . . . , .. ., . . . . . ·~ . . · ··s , , · ~ rit· = , • , 1 •• •• · · • • • • •• •• •• • --. •• • • ' ........ · . . . .. ~-.. "' . . .... ·· ... ··• •. . . .. •, . . ~ . ~ + I : .. •: ·"' -·· ' -'-.: ., •.,, .'· I\ ....... A . • ••• -. '\ I' . . .. ' I i . .. ······ ~ -''"" : · . .a ••• ,•'I .: \. · .. ,£/ r "~'·.,iP• ~-··.... , ,,... .... : ,·....._
• I 1 11 lf 1-.. · ·. , / / · ,,.. ~ '•, ·,. • .. ,' • , ,, ·~ •• ·v •., ,-.. ·.' . .\ 'f.l\ \ i ; ,I>•. •• : \ ~ •--°"~-=.-,
' ' ' ' ~ ••• !11.l-'" ,• -• ;, \ { .-'I ,• "•. l-·1 • .--•.sf'\•~, •, "•, . ,'~ ', .' • • ,;)r"""•'\, J...,:: ~~ I~ II •_ : \ (, .,• •. ,f •
[
,~• J,V ,' • • • • .,., <· ' \ • • .', • •, • • • -~ • • ' ' ., • • ' " ' . . I /. . I ' •. ,,. ' . . ·-· .... · . . . .,. ' ~ . ' I I I I I I I ~I_ ,•' ·', V ~ llff·, . . ,·-1'·.. '-.. .. ·.µ._ -~ •, .. ... ~-~ I ! . ! :-!
~-. ' / L... ,.. 'I • • . 'I L • 1:.:-.' ; 'LL 11 q .• .-.j ·. . ~----1-___ ..___~ --_ _____:___ __ __j - -~ _.L!.
ft '~ I . :
j"· -~ ! :1·······
lt-t-. , ~ -~~M1L~g~m~9=~ H-,
.;•
~vu C')
-l--
0
. -·
C> ' ··, • •
(,\)
I l l : I It I I
-l-·r-t--t--t-~-:--__;______:---1-_
r
·······--------~j15'
.... -......... ··. ··.
''\."'I
I
(.I) ' ..
I f-rt-1 I I I ~ --~ "< I 11
r : : .
~l-·· -····=~·: .b~·-HJ \ ·\.·~~I _ .. ··· / \ .
. ' . ---+---<---1-1
~ ----l____ -----· -'· •-• h l ... ..
.
I"' -,'°': ·. :,2:1 .. i.J
1-t--+-H---+-+--l-!---+-----1-·-----1----1 1-1-1---1 ~ •••••• I I
I ~
I • 1-1-~ ... ..
1 1 ~::~IIII: l : IIH-I :1~~~: ~ -==t
County of San Diego
Hydrology Manual
,;.._~
i:. la \• -~,. .,,,~
~,~-.. ~~~-
Rainfall lsopluvials
100 Year Rainfall Event -6 Hours
lsopluvial (inches)
~DPW ~GIS
-~;f~
-..-
SaTiG....,..........· ·I ........... -S
We Ha,..: !ia,:i Dit-go CMctul!
N THS 1W' Ill PACMDEDWllHOOl'WARRNITYOFANYKIHD. EmiEREXP~
CF Jr.ERCHWTABLFTV AHO f1TNESS RJRAPMTlCULAR Pl.,llPQl!E.
~-S.N1Rll#B-
C 0 +
ORIMJ'UED, INCWDIIO. BUT NCTUMITEDTO, n£ !MPl.ED WARRANTEII
TW1p ____ ....... _lllQICNI
If-+------------+-+, -----------t-,-t-1---1 :-'~'"d~-:"'llll9~-.CUII
1-1-----------+-+------------+--+-1 I lllllP_,,., ___ .... _.....,.. __ 1---~1-·M '-... ~ ·,~ .. ·-... . ;--it~--:~eXI ~-.. ---s ~ 11 · · . Ii
;:sc;:su·
3 o 3 MIies
P"--i I t~ffBWUllJ . . 1 II I 1 ~ 1 111 ' ~ 1$1 I ;
U
I
LII
EXHIBIT 4-100 YEAR -24 HOUR RAINFALL ISOPLUVIALS
U
I
I
U
I
I
I
U
I
I
I
I
I
1 17
I I ~ I j ' .
,~. . .. L " -~ ~ II ~
1 · .~I a I I 11 "' ::: , , -
b l I I L_l_ t,: :: I -33•3a r> ·:,I _ ~ I
,... • I .... I I -
;:: "" ' ! -
I ~====Ll~============~==i=H'==~~~~~~;;~~;:;~~~~~
O
range ; . . I • . , .. ,.. ;.~ ,..i..i , ~L ·1 . l" ·"· , ' C unty . . . . . . ~
I .:>p")im ..1..0· u· nt,y
1
··· , . .-,"-< ~iverside o . . . . . ·; ··· ·-.. · ·,.·.. ··. 1 •
1
·-••••••• , ~f 111 ~ ,<. . ) -',£ // ~: .. I ' . , ::. . . .. : <!'., "",: .°' ,._ ,:. .. . ·->:_-. : _. .. c,.~ ·, '.. ..•. " . j .· :.::::~::: ~._h \ / ~ ' ' ·-. ~ . .· -.-1. ,· ' ·. -... -... , ~-~ . ' • ·. '.,_ . • . ' . . : •, .• ··,,t ' • -,...... · ,. u:
0
J l/J/ :I i"b .. · .··«"? I I·. ••. -.. u;-, .. :··-. ' -~ , , -:a \ : .• . \ ·. •. ·• • ..
1
k
c :>:o-e-->·.. r· .f .. : ~~, -1-I\ ·.•. -·-. .,.,-,-,,,;·.-.:·.-;,;!) ·o .. -. , ~ '.. . , .. ·· •, : . ~I -I I I I l I ...... ·-.. . ,.. . .. ··. ·. .. ' . --.•. , .. -. : . .. . . , «o ··: ., • . . . . ._ .. ~ "· .. . . . . . : '
I 'f.,..,.. "••••••• ,• ., , • ~• , • " , .. ~, ' ,•, • •, •' '• • ' 0 S •.... • • • ' • • ' • ' '
•• • • •• ·• ,x, ' . • • ;~ . -. -<. "• , • • •, , ' • • • •• ', •, I \ • ''•. '• '··· · •• : ' '-' , I
-. -... • -· • ' k ' • .. • ,,.. --•.• • • ··, fJ [ : ,:•. • • • .. ' • : • • -~-----· .. ,-' ,,.. ,-··-"·•· ....... •,,,, . -•,
. ,,...., .... , -•• ·•• . ',. ;,.!'!"'•""• •• • • " -•• \ • ' • •• ~ ·,~. : • • • • •• • • -~,·---···. • ,,...,.. • ••••• 1 , " ·. . : . ," ,' . \, '1 •• • • .... , •• ., •, {{ ... -' • ·. • : • • ·. . . • . ~, '--···· .. '' . ' ' •. • ·;1, -.. . -~. : • • .!:.-• 'v..J:, , '. .,,._ • . • " I 1.: _ ... -._ ~ -
I
• • I' a • •. ~-. .... • •• ••• · / •, ·, k' • ••• I J ,. · , • • , •• , ,-. _ ~--· ..;. . . ·Y I • J •. t i •. •;7 • •, f"l.4 .'.!.··· • .. • LE ·. ', 'G-• . •. I l's;'~ •••••• ) IJ 1 ~--.. • ·.-. • • •• l: ~ ·: ·. ·. ·· .•... , .. -· . , ' . r· . : .. .._ 1s: • . • . T •• ·; -• ·• •• ·-... • -1·. i\,. ~~ -··· .-----------1. ...... _ .. I I I I ; I I I I I I '... ~~ . : •. ; Ir... ~ ~ . ""·~-
H--J-$<>~, '\~
I
~
I i 11 1 I 1 111 ffi=~ · · ... ' I ii:
1
~~ -....··· .. .J
'
,..
A'
I
.. '· ........ :-,, :· ---~· ~-~' :, ·-·· ··:· ,· ,..J •t"-..:,'-s·! , · I ~ "1l .//• •, · 'ff:P.. . / ~-'• : ·.'~,' /--.<}_ • , •r,t')f"' ,•' ,• • .'
,.,~ ~·~j (., . ,I. fl. . 'I : ,;4 ~-~ ···:----. ·• .: ... ~1 .. h'v ~.;..)~'--,-... •• : • , ~.v .... -· -·:.· · ,....-l'c:.+-:.........---t--.. .... --;.
1
.. ,,., .J.A~~IAr ... 7"' .,.. •••••• ~ I l'),r'? • ._L~: ... C!.!:>~ ~ •• • S.D. . •• • " ' • ----=·-~ ·;;;r.u· .. •• 3--' .:lllLII...AN B ' -,·-.. ti" I·) #""" , j. I • ,.. • ·"\ • ' ' .. • ', I ,,; .,,.."-;J •, ·..1.~ '' ,~l~·-1 ,...._ · . .,.. ' • , • • , •..• '\,.' .••.. "C --
. ~ ' ; r ;~ ...., ', /:--'1 lloD Jo;., • _re• \ \ , : I '. \ •, \ \.... ', , n,, 0 ()EJ .~)\II\ 1 1.--,../ ,' (~, ~ • ~-.. • /:. )p•-. · r,f ~-. • , 4.')..A ,,. , !'\ • , •• '• • "'-"' _.
-i' v::::;;;..-: . ,· Wr'oe~,.·~.:../7'~-•: ·~· . • · j/ •• • • ;u_ J. ·.~ L..·· '.1'-. • • ! .-·-·····~·r :::!. __ . (') .... . • I: .... i7 ... ,:,::•.J •'">.!.'!Jw.·· ~-• •• u .--~ '. • ...... · : ....... ...,,·· .. J-. ... . .. : .. ,=-'r" • • e!..
C.0 ~ , .~ .,.--~ F. ; ~ t:.· ~ "t : · :) ~ ll , .~.: ~.j '• .J :' ·.:·~-~ J·_"-.. .• : : : / •• ~.O· '\ 0-,.,.,. , ~-<, ... 1 · •••• ·11 ,·r~ il· ·• r· · · rf.Y. • •• · j···-•. ---··_;:··. • •.. , 11
0 ~ ~ ,... • . •• 1T··+ : ••. 1L • l,., I -•• • -v .. : di '. f. ·-c:::, • ·-.I • •• • •• . . • . \ C: --::> . .. . •• ·-. • . • • . • • • '¥ I • I .•.. •. ';. ·• . '• ..... '•, --t I j j (. ':,' '\. '••.. • •• • .. ~ ~•'T...,'¥-"'b ~ ' '. ;' • .• ' 1~ I •, '~ '• \ ... \'>!1' :•\ '-. -~-
• J I I I : f "\. r •aY. . I• y· , ~ .,..-• • , ' , • , , ........ 1..J(l "< 1 1 I I I I I I I I ·-~ , . \ i: •, ,-• . •• -. ~ _ ·., ~ ~ •, • -. •. . . . . 11 1 l _l_LJ.J 1 J ll. 1
' ,fttl,' ... ,, • ~ I'( .-.\' ,/, , • .. ~ .. ·-: . · J ~ I l : : \ \ .. ~ ;___1.,-..• ~ -· -~~~'\1.J' ~-.r.r'."' ~ --::.;i··· 1...,,.,-·t~·· •,. ·.-•. · l.!t' ' ;-~ ..
,. . ;,"3~--... . ..,,, uu· l . -I-~ C,
I J l I i I H-I : ; • •• •, •• -~ . . .
+-H <I ,. :·.
·-··--... ~ .,· ~
I
'' =Ft=t=' ===t=+F==== I I '
-.:, I I I I ;,!. I J J I I J. I I I 1 rJ.. · J_J___ : ' a I I i •~ I I .:i;C39' I -, 5 . I I I ,--I I --~!:') 1 1 ..-
1 I I i
"' «>' co --'.-I
County of San Diego
Hydrology Manual
--·~
'~~~
-f
. t,; ;;:;:
Rainfall lsopluvials
100 Year Rainfall Event -24 Hours
3
lsopluvial (inches)
_ .. DPW
~GIS 'ri~~~~
0
'IHS IW' IS ~AOll!CED WllHOOT'WARJWITV CF NIVKNI. EllHER EXPRESS CR MPUED. IICI.IJDINO, IUT NOT LNITED 10, Tl£ UII..IED WARRANT1ES
0/F liERClii\NT"ABIUTY ~ RTNEl&rOR APNmaJLAR P~
eopi,IOllllll•<H .... IRlJni-tw•p-----t,o-0"""°"" Hannlllon-m-CSU'dltoNl>OCU*l.iun,t!N
-...-.. aANIW).
l!Ho!lldld--lllnlnlonnllonwWcltlla_?ID_wlh ~ ... ..-IIJ--Mlpl.
3 Miles
H J
I
EXHIBIT 5- RUNOFF COEFFICIENTS FOR URBAN AREAS (Table
3-1)
I
H
I
I
I
I
I
I
I
I
I
I
I
I
I 18
mm - - - - - - - m m - - - - - mm -
San Diego County Hydrology Manual
Date: June 2003 Section: 3
Page: 6of26
Table 3-1
RUNOFF COEFFICIENTS FOR URBAN AREAS
Land Use Runoff Coefficient "C"
Soil Type
NRCS Elements County Elements % IMPER. A 'B C fl
Undisturbed Natural Terrain (Natural) Permanent Open Space 0* 0.20 0.25 0.30 0.35
Low Density Residential (LDR) Residential, 1.0 DU/A or less 10 0.27 0.32 0.36 0.41
Low Density Residential (LDR) Residential, 2.0 DU/A or less 20 0.34 0.38 0.42 0.46
Low Density Residential (LDR) Residential, 2.9 DU/A or less 25 0.38 0.41 0.45 0.49
Medium Density Residential (MDR) Residential, 4.3 DU/A or less 30 0.41 0.45 0.48 0.52
Medium Density Residential (MDR) Residential, 7.3 DU/A or less 40 0.48 0.51 0.54 0.57
Medium Density Residential (MDR) Residential,' 10.9 DU/A or less 45 0.52 0.54 0.57 0.60
Medium Density Residential (MDR) Residential, 14.5 DU/A or less 50 0.55 0.58 0.60 0.63
High Density Residential (HDR) Residential, 24.0 DU/A or less 65 0.66 0.67 0.69 0.71
High Density Residential (HDR) Residential, 43.0 DU/A or less 80 0.76 0.77 0.78 0.79
Commercial/Industrial (N. Corn) Neighborhood Commercial 80 0.76 0.77 0.78 0.79
Commercial/Industrial (G. Corn) General Commercial 85 0.80 0.80 0.81 0.82
Commercial/Industrial (O.P. Coin) Office Professional/Commercial 90 0.83 0.84 0.84 0.85
Commercial/Industrial (Limited I.) Limited Industrial ' 90 0.83 0.84 0.84 0.85
Commercial/Industrial (General I.) 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
I
j
I
I EXHIBIT 6- GUTTER & ROADWAY DISCHARGE VELOCITY
CHART (fig. 3-6)
I
I
I
I
I
I
I
I
I
I
I
I
I
I 19
------
• Ii A v-!a_•u_ _ a!a
VA!!1
___Al II I - AJR1 4
WAqM WAMWA _
IT Ii AV4ii1A
i 1a __
-
_
MIEW" no
u•uiw
—MUF4
VAIIII R.
bW..-AM
iuuuuuuiR$Ji -1.
F I G U R E
Gutter-and Roadway Discharge - Velocity Chart
3..61
I
I
I
I EXHIBIT 7- PRE-DEVELOPED DRAINAGE AREA
I
I
I
I
Li
I
L
I
I
I
I
I
I
I
1 20
I
LI
I
LEGEND
I DRAINAGE AREA ''
I
OFF—SITE FLOW DIRECTION -..-
ON—SITE FLOW DIRECTION EJ>
n
I
[ii
I
I
I
I
20 10 0 20 40 60
SCALE IN FEET
GRAPHIC SCALE
120
PRE-DEVELOPMENT
ONDONS
Planning * Engineering A Surveying
Solved.
200 E Washington Ave.. SuIte 200 A Escondido, CA 92025
0.760.741.3570 M AS S 0 N 9.760.74.1786
& ASSOCIATES, INC. www.masson-assoc.com
[! CITY OF CARLSBAD
ENGINEERING DEPARThIENT
TRAILS END DEVELOPMENT 1
6WN BYi I PROJECT NO. II DRARING No.1 CHED svi.................IJ II RVWD RYI_................II II I
I
ri
I
I
I
I
I
I
I
I EXHIBIT 8- POST-DEVELOPED DRAINAGE AREA
(Sub-basins)
I
I
I
I
I
I
I
I
I
I
I
I
I
1 .21
I
I
LEGEND
BUILDING
DRAINAGE SUB AREA I - I
LANDSCAPE
AC PAVEMENT
PERMEABLE PAVEMENTS ./
BIORETENIICM BARN (••' 3
PRIVATE STORM DRAIN 9- —25—
DR-OlE FLOW DIRECTION
OFF-SITE FLOW DIRECTION
DOAB4OPCOI TO SWALE OR LANDSCAPE <_< <
I
I
I
1
I
I
20 10 0 20 40 60
SCALE IN FEET
GRAPHIC SCALE
20
POST DEVELOPMENT
CONDONS
Planning A Engineering Surveying
Solved.
200 E Wa,h,nglov Ave.. Svite 200 A EscondIdo, CA 92025
m A S S c N F. 7A0.741.1
0.760.741.570
3 786
U ASSOCIATES, INC. .nosson-cs,oc.cor,
[j[CITY OF CARLSBAD
ENGINEERING DEPARTMENT 77
ETRAILS END DEVELOPMENT
PROJECT NO. I1DRAW1N0 NO.' I ClING BY I CT04-14A ii 481-lA I IRVW1) BY................lI
I
H
H