HomeMy WebLinkAboutPD 2022-0001; ISBELL RESIDENCE; HYDROLOGY & HYDRAULICS REPORT; 2022-06-16HYDROLOGY & HYDRAULICS
REPORT
PROJECT:
Isbell Residence Cacatua Street, Carlsbad GR2022-00005, DWG 536-2A
APN: 215-390-35
PREPARED FOR:
Scott and April Isbell P.O. Box 733
Bonsall, CA 92003
PREPARED BY:
Kristin L. Greene, P.E. dk GREENE CONSULTING, INC.
P.O. Box 143
Bonsall, CA 92003 J.N. 21-56
I hereby declare that I am the engineer of work for this project, that I have exercised responsible 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 standards.
June 19, 2022
Kristin L. Greene, P.E. C57860 Date
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~--Consulting, Inc.
EXPIRES: JUNE 30, 2022
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Contents
1.0 PROJECT INFORMATION .........................................................................................................1
1.1 SITE AND PROJECT DESCRIPTION ......................................................................................................... 1
1.2 EXISTING SITE TOPOGRAPHY AND DRAINAGE CONDITION ........................................................................ 4
1.3 PROPOSED SITE TOPOGRAPHY AND DRAINAGE CONDITION ..................................................................... 6
2.0 HYDROLOGY AND HYDRAULIC CALCULATIONS ........................................................................6
2.1 METHOD OF CALCULATION ................................................................................................................ 6
2.2 SOIL TYPE, IMPERVIOUSNESS, SELECTION OF “C” .................................................................................. 7
2.3 SUMMARY TABLE OF Q VALUES .......................................................................................................... 7
3.0 REPORT SUMMARY ................................................................................................................8
3.1 RECOMMENDATIONS ........................................................................................................................ 8
APPENDIX A ..................................................................................................................................... 10
EXISTING HYDROLOGY MAP .......................................................................................................................... 11
PROPOSED HYDROLOGY MAP........................................................................................................................ 12
APPENDIX B ..................................................................................................................................... 13
HYDROLOGY CALCULATION SPREADSHEET ....................................................................................................... 14
COUNTY OF SAN DIEGO HYDROLOGIC TABLES AND FIGURES 100 YEAR RAINFALL EVENT – 6 HOURS ........................ 15
COUNTY OF SAN DIEGO HYDROLOGIC TABLES AND FIGURES 100 YEAR RAINFALL EVENT – 24 HOURS ...................... 16
SOILS MAP FROM NRCS WEB SOIL SURVEY .................................................................................................... 22
LIST OF FIGURES
FIGURE 1-1. VICINITY MAP .................................................................................................................................................. 1
FIGURE 1-2. ISBELL RESIDENCE GOOGLE EARTH PLAN VIEW ....................................................................................................... 2
FIGURE 1-2. FRONT SLOPE .................................................................................................................................................. 2
FIGURE 1-2. EAST PROPERTY LINE LOOKING NORTHERLY ........................................................................................................... 3
FIGURE 1-2. EXISTING BROW DITCH (AT A LOWER ELEVATION THAN THE PAD) ................................................................................ 4
FIGURE 1-2. EXISTING PAD LOOKING SOUTHERLY TOWARD CACATUA STREET ............................................................................... 5
FIGURE 1-4. EXISTING OUTLET POINT ...................................................................................... ............................................3
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Hydrology & Hydraulics Report
City of Carlsbad
1.0 Project Information
1.1 Site and Project Description
This project provides for the development of a one-story single-family home with an attached garage. A vicinity map is shown below.
Figure 1-1. Vicinity Map
The lot is surrounded by existing single-family residences of similar size and type.
This report will focus on the Drainage Study in response to the grading and improvements associated with the development. In the pre-development condition, the site has one basin that outlets to the southwest. In the post-condition, the site has one basin that mimics the existing drainage pattern, and outlets to the southwest.
This report will evaluate the Q100 for the existing condition and compare it to the Q100 for the proposed condition by using the Modified Rational Method and County of San Diego’s Hydrology Manual to evaluate peak flows. If there is an increase in flow, mitigation measures will be created onsite via self-treating BMPs.
CITY OF OCEANSIDE
'8
PACIFIC
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Figure 1-2. Isbell Residence Google Earth Plan View
Figure 1-3. Front Slope
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Figure 1-4. East Property Line Looking Northerly
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1.2 Existing Site Topography and Drainage Condition
Topography of the site was provided by Dale Greene, LS is dated August 11, 2021. The site has been previously graded during the in 1970’s. The site drains to the street. Along the north property line there is an existing brow ditch. The highest elevation of
the property is approximately 5’ higher than the brow ditch, at the berm, creating the
existing drainage pattern southerly toward the street. The drainage areas will be divided into Basin “A” (12,197 s.f.) and Basin “B” (668 s.f.) which will be consistent in the Existing and Proposed condition.
Figure 1-5. Existing Brow Ditch on the North Property Line (at a lower elevation than the pad)
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Figure 1-6. Existing Pad Looking Southerly
Toward Cacatua Street
Generally, the existing Basin A drains southwesterly toward Cacatua Street and Basin
B drains to the existing PCC brow ditch and westerly. This pattern is maintained in the
Proposed condition. There is no “run-on” associated with this site.
See Appendix A, Existing Hydrology Map.
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Consulting, Inc.
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1.3 Proposed Site Topography and Drainage Condition
The proposed grading and drainage pattern will mimic the existing drainage condition and pattern, to the maximum extent practicable. The existing grading will be maintained. The
site will be developed with a one-story single-family home.
The site will be drained via 4” PVC pipes and 9” catch basins and atrium drains. The pipes will collect storm water runoff and convey the runoff to the lowest point of the property at the southwest corner of the property. A 6” pipe will collect all pipes toward the
southwesterly corner of the lot, then manifold to 2-3” pipes and then D-27 curb outlet will
convey the runoff to the street.
This is an infill lot. Drainage facilities were constructed per TM 2887-3 (La Costa Meadows Unit 3) and were sized to accommodate the runoff created by this development
with Basin “A”.
A brow ditch was built along the north side of the project and is within Basin “B”. There will no additional flows added to this area or conveyed via this ditch. The calculations provided are therefore, equal in the Existing and Proposed condition for Basin “B”.
See Appendix A, Proposed Hydrology Map.
2.0 Hydrology and Hydraulic Calculations
2.1 Method of Calculation
This Hydraulics & Hydrology Report was prepared using the following Manual: “San Diego County Hydrology Manual, June 2003.”
The Rational Method was used to determine the 100-year Storm Q values. The Rational
Method uses the following formula to establish 100-year flow:
Q = C I A
where:
Q = The peak runoff in cubic feet per second.
C = Runoff coefficient representing the ration of runoff to rainfall.
I = Time average intensity in inches per hour.
A = Area of sub-basin in acres.
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Consulting, Inc.
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2.2 Soil Type, Imperviousness, Selection of “C”
According to the soils report prepared for this project, by C. W. La Monte Company Inc., the Soils Group is classified as “D”. See Appendix B for a portion of the referenced soils report. The United States Department of Agriculture Natural Resources Conservation
Service Web Soil Survey online tool (Appendix B) also determined this property to be
classified as Soils Group D.
The runoff coefficient “C” will be based on this soils group for both the existing and proposed condition. The “C” for the existing conditions will be based on 0%
imperviousness (Cpre =0.35).
Although the lot is 12,865 s.f., only 12,197 s.f. (Basin “A”) will be developed. The proposed condition “C” value for Basin “A” will be based on the proposed condition of 55% impervious (6,735 sq. ft./12,197 sq. ft.) which will result in Cpost = 0.66. See
Appendix B, County of San Diego Hydrologic Tables and Figures, Table 3-1.
The table below details the proposed coefficients for each basin.
2.3 Summary Table of Q Values
Calculations were conducted for this project and are provided in the spreadsheet table in the Appendices.
PRE VS. POST SUMMARY
Node Pre Development Discharge Q100 (cfs)
Post Development Discharge Q100 (cfs) Difference (cfs)
Basin A 0.47 1.12 +0.65
Basin B 0.04 0.04 0.00
The difference between the pre and post condition is shown above. The development increases the impervious area. The existing improvements were sized to accommodate this infill project and this increase in runoff for Basin A. Calculations and maps of the
existing and proposed hydrology are provided in Appendix A & B.
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Consulting, Inc.
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3.0 Report Summary
3.1 Recommendations
This project encompasses development of a single-family home, driveway and landscaped areas on approximately 12,865 sq. ft. The proposed development does
increase the impervious surface and therefore generates an increase in runoff.
However, downstream facilities were sized and located to handle ultimate development and therefore can accommodate the additional runoff created by this development.
In my professional opinion, the proposed project will not substantially alter the existing
drainage pattern of the area. The project has been designed to maintain the historical
drainage pattern. The small increase from the existing condition to the post-development condition will not create downstream flooding or overwhelm the existing drainage facilities due to the development of this project.
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APPENDICES
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Appendix A
Existing Hydrology Map
Proposed Hydrology Map
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Existing Hydrology Map
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P.O. BOX 143
BONSALL, CA 92003
(760) 310-9408
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EXISTING HYDROLOGY MAP
DRAINAGE LEGEND
DRAINAGE PATH
BASIN DELINEATION
OUTFALL 1 FLOW LENGTH
-►-►-►-
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BENCH MARK
DESCRIPTION: ELEVATIONS ARE BASED ON MONUMENT NO. CLSB 033
LOCATION: __________________ _
RECORDED: RECORD OF SURVEY 17271
ELEVAT/ON: _~42~4~.7~65~-------DA TUM: NGVD 1929
" AS BU I LT"
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INSPECTOR
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ISABELL RESIDENCE
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GR2022-0005
DATE
DATE
DATE INITIAL DATE
ENGINEER OF WORK REVISION DESCRIPTION
INITIAL DATE INITIAL PROJECT NO.
PD2022-0001
DRAWING NO.
536-2A
0TH ER APPROVAL CITY APPROVAL
12
Proposed Hydrology Map
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DRAINAGE LEGEND
DRAINAGE PATH
BASIN DELINEATION
OUTFALL 1 FLOW LENGTH
dk Greene Consulting, Inc.
P.O. BOX 143
BONSALL, CA 92003
(760) 310-9408
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Consulting, Inc.
-►-►-►-
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" AS BU I LT"
BENCH MARK
DESCRIPTION: ELEVATIONS ARE BASED ON MONUMENT NO. CLSB 033 RCE __ _ EXP,----DATE
LOCATION: __________________ _
RECORDED: RECORD OF SURVEY 17271 REVIEWED BY:
ELEVATION: -~42~4~.7~65~-------DA TUM: NGVD 1929
INSPECTOR DATE
1-----+--+---------------t-----t-----t-------t--------i I S~EET I CITY OF CARLSBAD I SHE1ETS I
ENGINEERING DEPARTMENT
;:;P;R;O;P;O::;S:;ED~H::;.YD~R;O::;LO~G;Y::;F;;O;R;::: =======-====
1
DATE INITIAL DATE INITIAL
ENGINEER OF WORK REVISION DESCRIPTION OTHER APPROVAL
DATE INITIAL
CITY APPROVAL
ISABELL RESIDENCE
2932 CACATUA STREET
GR2022-0005
PROJECT NO.
PD2022-0001
DRAWING NO.
536-2A
13
Appendix B
Hydrology Calculation Spreadsheet
County of San Diego Hydrologic Tables and Figures
Soils Map
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Hydrology Calculation Spreadsheet
SYSTEM AREA
(AC)C
U/S
ELEVATION
(FT)
D/S
ELEVATION
(FT)
LENGTH
(FT)
SLOPE
(%)
P6(IN)
Ti from
Figure 3-3
TC
(MIN) 3-4
SUM
OF TC(MIN)
I
(IN/HR)
Q
(CFS)
Basin A 100 yr 0.28 0.35 501.0 491.0 170.0 5.9 2.8 9.8 0.0 9.8 4.8 0.47
Basin B 100 yr 0.02 0.35 502.0 492.0 62.0 16.1 2.8 4.2 0.0 5.0 7.4 0.04
Total Area 0.28
SYSTEM AREA
(AC)C
U/S
ELEVATION
(FT)
D/S
ELEVATION
(FT)
LENGTH
(FT)
SLOPE
(%)
P6(IN)
Ti from
Figure 3-3
TC
(MIN) 3-4
SUM
OF TC(MIN)
I
(IN/HR)
Q
(CFS)
Basin A-1 100 yr 0.28 0.66 497.4 490.0 185.0 4.0 2.8 6.8 0.0 6.8 6.1 1.12
Basin B 100 yr 0.02 0.35 502.0 492.0 62.0 16.1 2.8 4.2 0.0 5.0 7.4 0.04
Total Area 0.28
Pre Post Difference
Basin A 100 yr 0.47 1.12 0.65
Basin B 100 yr 0.04 0.04 0.00
POST DEVELOPMENT CONDITION SUMMARY
PRE DEVELOPMENT CONDITION SUMMARY
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County of San Diego Hydrologic Tables and Figures 100 Year Rainfall Event – 6 Hours
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Hydrology Manual
Rainfall Jsopluvials
100 Year Rainfall Event -24 Hours
lsOjll!Mal (nchos)
a , I • •·: i 1-/-,. •• .j.. --l. -+-H---l-, .j.~+-,I .... ' ""' : +"+-l-+-H---l-++-l-+-4--l-+-,-+-H--4--l-+-!-I-H---,..j.+-I. ~-+-~:~~~~~·I .. < §~===-=,_-
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17
2.8
100
2.8 5.2 54
See Appendix B, Hydrology Calculation Spreadsheet
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QUA.TIOIII
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I • lnrel'Sily (if\lllt)
P,s = 6-Hour Precipitation (in)
D = Duration (rnin),
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ntenslty•Duratlon 'Design Chart • Template
Directions for Appllcatron;
( 1) Frcrn l)re,;,c:i!l!tlon m~p~ delermlne 6 r 8nd 24 hr 8mounts
tor lb9 selected fraq11811C)'. 1bese ~ are included in thei
C(uwy Hydrology Manual (1 O·, ~. and 100 yr maps Inducted
in u,,,; Design aoo Proooduiru Manual).
(2) Adjll!II 6 hr preapita11on [If neces5ary) so 1hat It Is M1hin
lb9 rangei or 45% to 65% of the 24 hr pracipilation (nol
spplcaple to Des,ert).
(3) Plol 6 hr pre~itali.on on Iha riglTI s:ide of the mart.
(4) Otaw a line lhroogh the point p,ljr,aliel to lhe plotted lines.
(5) This lime is tme intensi1y-duration curve for lhe locetion
being 8fllalyzed.
,._Pri'~tle>n FOl'!n:
(a) Selecled frequency ___ ye,ar
p
(b) p6 = m .. 1'24 = '.:§.P = •1r,l2J ----24
(c) Adjusled P5(2I = __ in.
(0) t,, ■ __ min,, }
(e) I = __ in.lhr.
Note: This chart replaces the ln1emity-Ometion-Frequency
curves used since· 1965 .
PS '1.5 .2 2c5 3 U 4 4,5
Cuol"'1 I I I I I I
iS 2.63 .J.9!J t'a.2
7 2.12 3.1! 4.2
10 1.68 2.53 3.3
1~ 1.,0 U5 2.59 3-N 3.E9 4-54 5.19 !illol
,5 U
I
211 1.09 l.ti2 2.15 2.li9 11.2'~ ':J..TT 4.;n 4.lll! 5,39 &.m MG
25 U3. 1.40 1.8'1 2.:ll 2.IIO 3.V 3.73 ~.20 4JJ7513 UO
)() o.83 1.2, 1.ee 201 2.4~ ~~ :;i.a:i 3.n ,,15 ,si, , ge
ct() 0~ U 3 1.38 1.7? 2.07 :u, 2.76 3-10 ~AS 3.79 4-ll
50 o.oo D.90 1.1"9 1.49 1.79 2.te 2.:39 ll'.M 2.'911 3.2!1 :!.!SIi
lill O.fi3 0.f!O 1.06 1,:ll 1.59 1116 2. ;2 2.39 2JJ5 2 Q2 3.18
90 0,1 U 1 0~ l.°'1 1.2$ I "3 ,.E;:l 2.Q,I 2-25 2.4~
120 O.!JC D.S I ,0.68 D.BS 1.02' ,_ 19 1.36 I :ro ,m 2..04
150 li.2!l O.u 0.C9 0.7::! 0.8& 1.03 1.19"-f-'=e-+-"'H,'-'-..'1 1.!i2 1.,t;
100 -0.2'6 o.39 o.s2 o.ei; 0.1& og1. 1 °' 1.31 ~
2fQ , o,;22 o.33 ,o.~• 0,54 o.es 0.713 0.87 1.oa -u g""T"Ulf
300 +D. !'!I 0.28 D.-38 D.47 O.!& 0..156 0..7& 0:94! 1..aJ I. I~
alill I 0.11 0.2s o.3'l o.a2 o.so o.58 o lf7 011<1 0.!12 ,.oo
3-1
18
Existing Impervious Surface = 0% impervious - C = 0.35
Proposed Impervious Surface = 6,735 𝑠𝑠𝑠𝑠.𝑓𝑓𝑓𝑓.12,197 𝑠𝑠𝑠𝑠.𝑓𝑓𝑓𝑓. = 0.55 => C = 0.66
Existing
C=0.35
Proposed
C=0.66
San Diego County Hydrology Manual
Date: June 2003
Table 3-1
Section:
Page:
RUNOFF COEFFICIENTS FOR URBAN AREAS
Laud Use Runoff Coefficient "C"
Soil Type
NRCS Elements County Elen1ents ¾IMPER. A B
Undisturbed Natural Terrain 1 atural) Permanent Open Space O* 0.20 0.25
Low Density Residential (LDR) Residential, LO DU/A or less 10 0_27 0.32
Low Density Residential (LDR) Residential, 2_0 DU/A or less 20 0-34 0.38
Low Density Residential (LDR) Residential, 2_9 DU/A or less 25 0-38 0-41
Medium Density Residential (MDR) Reside.ntial, 4.3 DU/A or less 30 0-41 045
Medium Density Residential (MDR) Residential, 7_3 DU/A or less 40 0-48 0.51
Medium Density Residential (MDR) Residential, 10.9 D /A or less 45 0.52 0.54
Medium Density Residential (MDR) Residential, 14.5 D /A or less 50 0.55 0.58
High Density Residential (HDR) Residential, 24.0 D /A or less 65 0.66 0.67
High Density Residential (HDR) Residential, 43.0 D /A or less 80 0_76 077
Commercial/Industrial (N_ Com) eighborhood Commercial 80 0_76 077
Commercial/Industrial (G_ Com) General Commercial 85 0.80 0.80
Commercial/Industrial (O_P_ Com) Office Professional/Commercial 90 0_83 0.84
Commercial/Industrial (Limited L) Limited Industrial 90 0_83 0.84
Commercial/Industrial (General L) General Industrial 95 0.87 0.87
3
6 of26
C D
0.30 0_35
0.36 0-41
0-42 0-46
0-45 0-49
0-48 0-52
0-54 0-57
0.57 0.60
0.60 0.63
0.69 0.71
0_78 0_79
0_78 0_79
0.81 0.82
0_84 0_85
0.84 0_85
0.87 0.87
*The values associated with 0% impervious may be used for direct calculation of the rnnoff coefficient as described in Section 3 .1-2 (representing the pervious mnoff
coefficient, Cp, for the soil type), or for areas that ,vill re.main undisturbed in perpetuity_ Justification must be given that the area will rema in natural forever (e.g., the area
is located in Cle, eland National Forest).
D I A = dwelling units per acre
NRCS = ational Resources Conservation Service
19
Element*
Natural
LDR
LDR
LDR
MDR
MDR
MDR
MDR
HDR
HDR
N.Com
G.Com
O.P./Com
Limited I.
General I.
Table 3-2
MAXIMUM OVERLAND FLOW LENGTH (LM)
& INITIAL TIME OF CONCENTRATION (Ti)
DU/ .5% 1% 2% 3% 5%
Acre LM Ti LM Ti LM Ti LM Ti LM Ti
50 13.2 70 12.5 85 10.9 100 10.3 100 8.7
I 50 12.2 70 11.5 85 10.0 100 9.5 100 8.0
2 50 11.3 70 10.5 85 9.2 100 8.8 100 7.4
2.9 50 10.7 70 10.0 85 8.8 95 8.1 100 7.0
4.3 50 10.2 70 9.6 80 8.1 95 7.8 100 6.7
7.3 50 9.2 65 8.4 80 7.4 95 7.0 100 6.0
10.9 50 8.7 65 7.9 80 6.9 90 6.4 100 5.7
14.5 50 8.2 65 7.4 80 6.5 90 6.0 100 5.4
24 50 6.7 65 6.1 75 5.1 90 4.9 95 4.3
43 50 5.3 65 4.7 75 4.0 85 3.8 95 3.4
50 5.3 60 4.5 75 4.0 85 3.8 95 3.4
50 4.7 60 4.1 75 3.6 85 3.4 90 2.9
50 4.2 60 3.7 70 3.1 80 2.9 90 2.6
50 4.2 60 3.7 70 3.1 80 2.9 90 2.6
50 3.7 60 3.2 70 2.7 80 2.6 90 2.3
*See Table 3-1 for more detailed description
10%
LM Ti
100 6.9
100 6.4
100 5.8
100 5.6
100 5.3
100 4.8
100 4.5
100 4.3
100 3.5
100 2.7
100 2.7
100 2.4
100 2.2
100 2.2
100 1.9
20
I-w w u. 0 ~
w u z < I-/I)
i5
w /I) a:: ::,
0 u a:: ~ ~
EXAMPLE:
Given: Watercourse Dislance (0) = 70 Feet
Slope (s) = 1.3%
Runoff Coefficient (C) = 0.41
Overland Flow Time (T) = 9.5 Minutes
T = 1.8 (1.1-C) 1/o
'Vs
SOURCE: Airporl Drainage, Federal Aviation Administration, 1965
FIGUR E
Rational Formula -Overland Time of Flow Nomograph 3-3
21
LI.E
Feet
5000
4000
EQUATION
Tc • (1~~')°'385
Tc Time of concentration (h,oura)
L • Watercourse Distance (mllOs)
~E Change In elevalion along
effective slope line (See Figure 3-5)(feet)
3000
2000
1000
900
800
"IDO ~,
400
300
200
LI.E
100
50 ..,
30
20
10
SOURCE: California Division of Highways (1941) and Kirpich {1940)
0.5
4000
3000 ' ' 2000
1800 1600
1400
1200
1000 900
800
700
600
500
400
300
200
L
Nomogroph for Determinootion of
Te
Hours Minutes
60
..,
30
' ' ' ' '
6
4
Te
Time of Concentrofion (Tc) or Travel Time (Tl) for Natural \11:ltersheds
FIGURE ~
22
Soils Map from NRCS Web Soil Survey
This property was determined to be Hydrologic Soil Group D per the United States Department of Agriculture Natural Resources Conservation Service (NRCS) Web Soil Survey online tool.
Report -Hydrologic Soil Group and Surface Runoff
Absence of an entry indicates that the data were not estimated. The dash ind.icates no
documented presence.
San Diego County Area, Ca liforn ia
Map symbol and soil nanie Pct. of Surface
HrE2-Huerhuero loam, 15 to
30 percent slopes, eroded
Huerhuero
map Runoff
unit
85 Very
h inh
Hydrologic Soil
Group
D
6/20/22, 10:43 AM Open Channel Flow Calculator
https://www.eng.auburn.edu/~xzf0001/Handbook/Channels.html 1/1
The open channel flow calculator
Select Channel Type:
Circle
Depth from Q Select unit system: Feet(ft)
Channel slope: .02
ft/ft Water depth(y): 0.3 ft Radius (r).165
ft
Flow velocity 3.42
ft/s LeftSlope (Z1): to 1 (H:V)RightSlope (Z2):
to 1 (H:V)
Flow discharge .28
ft^3/s
Input n value .013 or select n
Calculate!Status:Calculation finished Reset
Wetted perimeter 0.84
ft Flow area 0.08 ft^2 Top width(T)0.18
ft
Specific energy 0.48
ft Froude number 0.9 Flow status
Subcritical flow
Critical depth 0.29
ft Critical slope 0.0203 ft/ft Velocity head 0.18
ft
Copyright 2000 Dr. Xing Fang, Department of Civil Engineering, Lamar University.
4" pipe is acceptable for small areas.
~ ~~ f--T---l l---1 ---I
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Rectangle Trapezoid Triangle Circle
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11
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6/20/22, 10:51 AM Open Channel Flow Calculator
https://www.eng.auburn.edu/~xzf0001/Handbook/Channels.html 1/1
The open channel flow calculator
Select Channel Type:
Circle
Depth from Q Select unit system: Feet(ft)
Channel slope: .10
ft/ft Water depth(y): 0.29 ft Radius (r).25
ft
Flow velocity 9.6131
ft/s LeftSlope (Z1): to 1 (H:V)RightSlope (Z2):
to 1 (H:V)
Flow discharge 1.12
ft^3/s
Input n value .013 or select n
Calculate!Status:Calculation finished Reset
Wetted perimeter 0.87
ft Flow area 0.12 ft^2 Top width(T)0.49
ft
Specific energy 1.73
ft Froude number 3.44 Flow status
Supercritical flow
Critical depth 0.49
ft Critical slope 0.0351 ft/ft Velocity head 1.43
ft
Copyright 2000 Dr. Xing Fang, Department of Civil Engineering, Lamar University.
6" pipe is acceptable
~ ~~ f--T---l l---1 ---I
~I, ' / ~~(L ~ ll zl z2 V l-b-l ~z
Rectangle Trapezoid Triangle Circle
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5/10/22, 12:36 PM Open Channel Flow Calculator
https://www.eng.auburn.edu/~xzf0001/Handbook/Channels.html 1/1
The open channel flow calculator
Select Channel Type:
Circle
Depth from Q Select unit system: Feet(ft)
Channel slope: 0.1
ft/ft Water depth(y): 0.26 ft Radius (r).165
ft
Flow velocity 7.7997
ft/s LeftSlope (Z1): to 1 (H:V)RightSlope (Z2):
to 1 (H:V)
Flow discharge .56
ft^3/s
Input n value .013 or select n
Calculate!Status:Calculation finished Reset
Wetted perimeter 0.72
ft Flow area 0.07 ft^2 Top width(T)0.27
ft
Specific energy 1.2
ft Froude number 2.67 Flow status
Supercritical flow
Critical depth 0.33
ft Critical slope 0.086 ft/ft Velocity head 0.94
ft
Copyright 2000 Dr. Xing Fang, Department of Civil Engineering, Lamar University.
1.12 CFS / 2 = .56 CFS PER 3" PIPE = > OKAY!
~ ~~ f--T---l l---1 ---I
~I, ' / ~~(L ~ ll zl z2 V l-b-l ~z
Rectangle Trapezoid Triangle Circle
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Figure 2-5
5
4
0-15 Operatin as Orifice (Ae=2.4
3
Grate Inlets as Orifice
2 t ,"J
<r"' -¢:: -.. 1 s 0.9 ra 0.8 3r: 0.7 ... 0
.c 0.6 -C. 0.5
Q) ./ C 0.4
0.3
~
0.2 +-,.<c:.,,,,c:...._--,;,,c_-1',,L._--,,:::__ ___ +.--+---+---+---------+------1 ~ i
0-15Lon E ge,Agains Curb(P9=3.1 ft) il:
'----0-15 Flo fr m L, Oirec ions (P8=4.6 ft) I
I f
0.1 +-----+-------+--+-1----+---------l-----' -o:
1 2 3 4 5 6 7 8 910 20 30 40 50
Grate Inlet Capacity (ft3/s)
ejll= 0.(15" pj_
f.;;: 11&~ :J-.30
Figure 2-5 Capacity of Grate Inlets in Sump Locations p e., •-3:) V-z. {-Z, 3 S) :==. .:L 'l.3
San Diego County Drainage Design Manual ( July 2005)
Page 2-15 ~c~ clAolrL cMl la.~&l;:,1 /
/),---,'5 C t, (7'0-.