HomeMy WebLinkAboutCT 12-03; 201 Walnut Townhomes; Hydrology Report; 2015-03-10HYDROLOGY STUDY
for
201 Walnut Townhomes, Carlsbad, CA
CT 12-03
City of Carlsbad, CA
PREPARED FOR:
201 Walnut, LLC
17828 Villamoura Drive
Poway, CA, 92064
Date: June 1, 2014
Revised: October 3, 2014
Revised: March 10,2015
PREPARED BY:
Pasco Laret Suiter & Associates
535 N. Highway 101, Suite A
Solana Beach, CA 92075
(858) 259-8212
RECEIVED
JUL 0 6 2015
LAND DEVELOPMENT
ENGINEERING
BRIAN ARDOLINO, RCE 71651 DATE
Preliminary Hydrology Study for Walnut Townhomes
PLSA1939
TABLE OF CONTENTS
SECTION PAGE
Executive Summary 1.0 3
Introduction 1.1 3
Existing Conditions 1.2 3
Proposed Project 1.3 3
Summary of Results and Conditions 1.4 4
Conclusions 1.5 4
References 1.6 5
Methodology 2.0 6
Introduction 21 6
County of San Diego Criteria 22 6
Runoff coefficient determination 23 7
Hydrologic Analyses 3.0 8
Pre-Developed Hydrologic Analysis 3.1 9
Post-Developed Hydrologic Analysis 3.2 14
Hydraulic Calculations 4.0 19
Appendix 5.0
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1.0 EXECUTIVE SUMMARY
1.1 Introduction
This Hydrology Study for the Walnut Townhomes project has been prepared to analyze the
hydrologic and hydraulic characteristics of the existing and proposed project site. This
report intends to present both the methodology and the calculations used for determining
the runoff from the project site in both the pre-developed (existing) conditions and the post-
developed (proposed) conditions produced by the 100 year 6 hour storm. In addition this
report will propose the sizing of all necessary storm drain facilities and storm drain piping
necessary for the storm drain system to safely convey the runoff from the 1 OO-year rainfall
event.
1.2 Existing Conditions
The property is geographically located at N 33"09'16" W 117''20'54". The site is bordered by
a residential development on the south, Garfield Street to the west. Walnut Avenue to the
North and Lincoln Street to the east. The project site is located in the Aqua Hediona
Lagoon Area and more speciflcally, the Los Monos Sub-Area (904.31). The project is
located at 201 Walnut Avenue.
The existing project site consists of three APN's, two are undeveloped and one is currendy
occupied by an existing residence and driveway. The site consists mosdy of a gende slope
from west to east. Drainage from the existing site sheet flows in an easterly direction across
the project site to Lincoln Street. The runoff is then conveyed in gutters along Lincoln Street
and Walnut Avenue, and ultimately discharges onto the train tracks at the end of Walnut
Avenue.
1.3 Proposed Project
The intent of proposed projects is to develop the proposed project site into a 14-unit
attached townhome complex with associated landscaping and hardscape improvements, as
well as frontage improvements along Garfield Street, Walnut Avenue, and Lincoln Street.
The project proposed grading to create multi-level pads for the construction of the
townhomes and the construction of all underground utilities typically associated with
residential development. The improvements proposed along Garfield Street, Walnut Avenue
and Lincoln Street include the addition of curb and gutter, as well as parkway, driveway and
sidewalk improvements.
The proposed drainage design includes the construction of pavement, curb and gutter along
the street frontages, and Bioretention BMP areas for priority storm water treatment. The
proposed pads will utilize grading to drain the pads west to east and ultimately onto Walnut
Avenue as it does in the existing condition.
We beHeve the proposed storm drain system will not adversely affect the downstream system
negatively.
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PLSA 1939
To address the storm water quality goals established for this development, proposed
permanent Best Management Practice (BMP) and treatment methods will be incorporated
into the storm water runoff design. The proposed BMP's include multiple bioretention
areas, which are intended to mitigate peak flows by utiUzing the existing optimal soil on site
and proper detention design. The bioretention areas will also serve as settling basins and are
also designed to meet hydromodification criteria.
1.4 Summary of Results
Upon performing hydrologic analysis of the project site in both the proposed developed and
existing condition the following results were produced. One discharge point was analyzed.
In the predeveloped condition indicates that the 1 OO-year peak flow is 1.70 cfs with a time of
concentration of 9.84 min based on an area of 0.9 AC.
In the postdeveloped condition indicates that the 1 OO-year peak flow is 2.86 cfs with a time
of concentration of 6.83 min based on an area of 0.9 AC.
The increase in peak flow rate has been addressed by using the proposed bioretention areas
as detention basins. 20" of crushed rock is proposed at the bottom of the bioretention areas
with a perforated pipe in order to mitigate the peak flow rate. Per the rational method
hydrograph data provided in this report, an increase in storage volume is approximately 890
cf. The proposed storage volume with a void ratio of 40% is 920 cf which will properly
mitigate the increase due to the development.
1.5 Conclusions
Based on the discussion in this report it is the professional opinion of Pasco Laret Suiter &
Associates, Inc. that the existing drainage system on the corresponding Tentative Map will
function to adequately intercept, contain and convey flow to the appropriate points of
discharge.
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1.6 References
"San Diego County Hydrology Manual", revised June 2003, County of San Diego, Department of
Public Works, Flood Control Section.
"Califomia Regional Water Quality Control Board Order No. 2009-0009-DWQ, "California
Regional Water Control Board, San Diego Region (SDRWQCB).
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2.0 METHODOLOGY
2.1 Introduction
The hydrologic model used to perform the hydrologic analysis presented in this report
utilizes the Ration Method (RM) equation, Q=CIA. The RM formula estimates the peak
rate of runoff based on the variables of area, runoff coefficient, and rainfall intensity. The
rainfall intensity (I) is equal to:
I = 7.44 X Ps x D-"'*^
Where:
I = Intensity (in/hr)
Pe — 6-hour precipitation (inches)
D = duration (minutes — use Tc)
Using the Time of Concentration (Tc), which is the time required for a given element of
water that originates at the most remote point of the basin being analyzed to reach the point
at which the mnoff from the basin is being analyzed. The RM equation determines the
storm water runoff rate (Q) for a given basin in terms of flow (typically in cubic feet per
second (cfs) but sometimes as gallons per minute (gpm)). The RM equation is as follows:
Q= CIA
Where:
Q= flow (in cfs)
C = mnoff coefficient, ratio of rainfall that produces storm water
runoff (runoff vs. infiltration/evaporation/absorption/etc)
I = average rainfall intensity for a duration equal to the Tc for the
area, in inches per hour.
A = drainage area contributing to the basin in acres.
The RM equation assumes that the storm event being analyzed delivers precipitation to the
entire basin uniformly, and therefore the peak discharge rate will occur when a raindrop falls
at the most remote portion of the basin arrives at the point of analysis. The RM also
assumes that the fraction of rainfall that becomes runoff or the mnoff coefficient C is not
affected by the storm intensity, I, or the precipitation zone number.
In addition to the above Ration Method assumptions, the conservative assumption that all
mnoff coefficients utilized for this report are based on type "D" soils.
2.2 County of San Diego Criteria
As defined by the County Hydrology Manual dated June 2003, the rational method is the
preferred equation for determining the hydrologic characteristics of basins up to
approximately one square mile in size. The County of San Diego has developed its own
tables, nomographs, and methodologies for analyzing storm water runoff for areas within
the county. The County has also developed precipitation isopluvial contour maps that show
even lines of rainfall anticipated from a given storm event (i.e. lOO-year, 6-hour storm).
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One of the variables of the RM equation is the mnoff coefficient, C. The mnoff coefficient
is dependent only upon land use and soil type and the County of San Diego has developed a
table of Runoff Coefficients for Urban Areas to be applied to basin located within the
County of San Diego. The table categorizes the land use, the associated development
density (dwelling units per acre) and the percentage of impervious area. Each of the
categories listed has an associated runoff coefficient, C, for each soil type class.
The County has also illustrated in detail the methodology for determining the time of
concentration, in particular the initial time of concentration. The County has adopted the
Federal Aviation Agency's (FAA) overland time of flow equation. This equation essentially
limits the flow path length for the initial time of concentration to lengths of 100 feet or less,
and is dependent on land use and slope.
2.3 Runoff Coefficient Determination
As stated in section 2.2, the mnoff coefficient is dependent only upon land use and soil type
and the County of San Diego has developed a table of Runoff Coefficients for Urban Areas
to be appKed to basin located within the County of San Diego. The table, included at the
end of this section, categorizes the land use, the associated development density (dwelling
units per acre) and the percentage of impervious area.
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PLSA 1939
3.0 HYDROLOGIC ANALYSES
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PLSA 1939
3.1 PREDEVELOPED CONDITION HYDROLOGIC ANALYSIS
RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE
Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT
2003,1985,1981 HYDROLOGY MANUAL
(c) Copyright 1982-2008 Advanced Engineering Software (aes)
Ver. 15.0 Release Date: 04/01/2008 License ID 1452
Analysis prepared by:
+ + + + + * DESCRIPTION OF STUDY ****************************
* 100 YEAR STORM HYDROLOGIC ANALYSIS - PREDEVELOPED CONDITION *
* 201 WALNUT TOWNHOMES *
* PLSA 1939 - 03.01.13 *
FILE NAME: 1939PRE.DAT
TIME/DATE OF STUDY: 13:30 03/01/2013
USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION:
2 003 SAN DIEGO MANUAL CRITERIA
USER SPECIFIED STORM EVENT(YEAR) = 100.00
6-HOUR DURATION PRECIPITATION (INCHES) = 2.500
SPECIFIED MINIMUM PIPE SIZE(INCH) = 3.00
SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE =0.95
SAN DIEGO HYDROLOGY MANUAL "C"-VALUES USED FOR RATIONAL METHOD
NOTE: CONSIDER ALL CONFLUENCE STREAM COMBINATIONS
FOR ALL DOWNSTREAM ANALYSES
*USER-DEFINED STREET-SECTIONS FOR COUPLED PIPEFLOW AND STREETFLOW MODEL*
HALF- CROWN TO STREET-CROSSFALL: CURB GUTTER-GEOMETRIES: MANNING
WIDTH CROSSFALL IN- / OUT-/PARK- HEIGHT WIDTH LIP HIKE FACTOR
NO. (FT) (FT) SIDE / SIDE/ WAY (FT) (FT) (FT) (FT) (n)
1 30.0 20.0 0.018/0.018/0.020 0.67 2.00 0.0313 0.167 0.0150
GLOBAL STREET FLOW-DEPTH CONSTRAINTS:
1. Relative Flow-Depth = 0.00 FEET
as (Maximum Allowable Street Flow Depth) - (Top-of-Curb)
2. (Depth)*(Velocity) Constraint = 6.0 (FT*FT/S)
*SIZE PIPE WITH A FLOW CAPACITY GREATER THAN
OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.*
FLOW PROCESS FROM NODE 1.00 TO NODE 1.10 IS CODE = 21
>»»RATIONAL METHOD INITIAL SUBAREA ANALYSIS««<
*USER SPECIFIED(SUBAREA):
USER-SPECIFIED RUNOFF COEFFICIENT = .5600
S.C.S. CURVE NUMBER (AMC II) = 0
INITIAL SUBAREA FLOW-LENGTH(FEET) = 88.00
UPSTREAM ELEVATION(FEET) = 62.00
DOWNSTREAM ELEVATION(FEET) = 56.00
ELEVATION DIFFERENCE(FEET) = 6.00
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SUBAREA OVERLAND TIME OF FLOW(MIN.) = 4.809
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.587
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.
SUBAREA RUNOFF(CFS) = 0.07
TOTAL AREA(ACRES) = 0.02 TOTAL RUNOFF(CFS) = 0.07
****Sr**TtTt + * + * + + + + + *-Jr + + + *^Jf:JrTt* + + + + -*- + + + + *** + -*r-*r**** + *-*r*:Jr + ** + + + * + + -* + + *
FLOW PROCESS FROM NODE 1.20 TO NODE 1.20 IS CODE = 81
»»>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW««<
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.587
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.
*USER SPECIFIED(SUBAREA):
USER-SPECIFIED RUNOFF COEFFICIENT = .7200
S.C.S. CURVE NUMBER (AMC II) = 0
AREA-AVERAGE RUNOFF COEFFICIENT = 0.6909
SUBAREA AREA(ACRES) = 0.09 SUBAREA RUNOFF(CFS) = 0.43
TOTAL AREA(ACRES) = 0.1 TOTAL RUNOFF(CFS) = 0.50
TC(MIN.) = 4.81
FLOW PROCESS FROM NODE 1.20 TO NODE 4.00 IS CODE = 62
»»>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA««<
»»> (STREET TABLE SECTION # 1 USED) ««<
UPSTREAM ELEVATION(FEET) = 52.00 DOWNSTREAM ELEVATION(FEET) = 50.30
STREET LENGTH(FEET) = 118.00 CURB HEIGHT(INCHES) = 8.0
STREET HALFWIDTH(FEET) = 30.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 20.00
INSIDE STREET CROSSFALL(DECIMAL) = 0.018
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.018
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
STREET PARKWAY CROSSFALL(DECIMAL) = 0.020
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150
Manning's FRICTION FACTOR for Baclc-of-Walk Flow Section = 0.0200
**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 0.50
STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:
STREET FLOW DEPTH(FEET) = 0.2 0
HALFSTREET FLOOD WIDTH(FEET) = 2.00
AVERAGE FLOW VELOCITY(FEET/SEC.) = 2.61
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 0.52
STREET FLOW TRAVEL TIME(MIN.) = 0.75 Tc(MIN.) = 5.56
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.14 8
AREA-AVERAGE RUNOFF COEFFICIENT = 0.691
SUBAREA AREA(ACRES) = 0.00 SUBAREA RUNOFF(CFS) = 0.00
TOTAL AREA(ACRES) = 0.1 PEAK FLOW RATE(CFS) = 0.50
END OF SUBAREA STREET FLOW HYDRAULICS:
DEPTH(FEET) = 0.2 0 HALFSTREET FLOOD WIDTH(FEET) = 2.00
FLOW VELOCITY(FEET/SEC.) = 2.61 DEPTH*VELOCITY(FT*FT/SEC.) = 0.52
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 4.00 = 206.00 FEET.
FLOW PROCESS FROM NODE 4.00 TO NODE 4.00 IS CODE = 1
»»>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE««<
TOTAL NUMBER OF STREAMS = 3
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CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE:
TIME OF CONCENTRATION(MIN.) = 5.56
RAINFALL INTENSITY(INCH/HR) = 6.15
TOTAL STREAM AREA(ACRES) = 0.11
PEAK FLOW RATE(CFS) AT CONFLUENCE = 0.50
FLOW PROCESS FROM NODE 2.00 TO NODE 2.10 IS CODE = 21
»»>RATIONAL METHOD INITIAL SUBAREA ANALYSIS««<
*USER SPECIFIED(SUBAREA):
USER-SPECIFIED RUNOFF COEFFICIENT = .4000
S.C.S. CURVE NUMBER (AMC II) = 0
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 59.8 0
DOWNSTREAM ELEVATION(FEET) = 57.7 0
ELEVATION DIFFERENCE(FEET) = 2.10
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 9.151
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN
THE MAXIMUM OVERLAND FLOW LENGTH = 8 6.50
(Reference: Table 3-lB of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION!
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.460
SUBAREA RUNOFF(CFS) = 0.2 9
TOTAL AREA(ACRES) = 0.16 TOTAL RUNOFF(CFS) = 0.2 9
FLOW PROCESS FROM NODE 2.10 TO NODE 2.20 IS CODE = 52
»»>COMPUTE NATURAL VALLEY CHANNEL FLOW««<
»»>TRAVELTIME THRU SUBAREA««<
ELEVATION DATA: UPSTREAM(FEET) = 57.70 DOWNSTREAM(FEET) = 52.00
CHANNEL LENGTH THRU SUBAREA(FEET) = 120.00 CHANNEL SLOPE = 0.0475
NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION
CHANNEL FLOW THRU SUBAREA(CFS) = 0.2 9
FLOW VELOCITY(FEET/SEC) = 3.27 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL)
TRAVEL TIME(MIN.) = 0.61 Tc(MIN.) = 9.76
LONGEST FLOWPATH FROM NODE 2.00 TO NODE 2.20 = 220.00 FEET.
FLOW PROCESS FROM NODE 2.20 TO NODE 2.20 IS CODE = 81
»»>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW««<
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.278
*USER SPECIFIED(SUBAREA):
USER-SPECIFIED RUNOFF COEFFICIENT = .4600
S.C.S. CURVE NUMBER (AMC II) = 0
AREA-AVERAGE RUNOFF COEFFICIENT = 0.4425
SUBAREA AREA(ACRES) = 0.39 SUBAREA RUNOFF(CFS) = 0.77
TOTAL AREA(ACRES) = 0.5 TOTAL RUNOFF(CFS) = 1.04
TC(MIN.) = 9.76
FLOW PROCESS FROM NODE 2.20 TO NODE 4.00 IS CODE = 52
»»>COMPUTE NATURAL VALLEY CHANNEL FLOW««<
»»>TRAVELTIME THRU SUBAREA««<
ELEVATION DATA: UPSTREAM(FEET) = 52.00 DOWNSTREAM(FEET) = 50.30
CHANNEL LENGTH THRU SUBAREA(FEET) = 21.00 CHANNEL SLOPE = 0.0810
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CHANNEL FLOW THRU SUBAREA(CFS) = 1.04
FLOW VELOCITY(FEET/SEC) = 4.30 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL)
TRAVEL TIME(MIN.) = 0.08 Tc(MIN.) = 9.84
LONGEST FLOWPATH FROM NODE 2.00 TO NODE 4.00 = 241.00 FEET.
FLOW PROCESS FROM NODE 4.00 TO NODE 4.00 IS CODE = 1
>»»DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE««<
TOTAL NUMBER OF STREAMS = 3
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 2 ARE:
TIME OF CONCENTRATION(MIN.) = 9.84
RAINFALL INTENSITY(INCH/HR) = 4.2 6
TOTAL STREAM AREA (ACRES) = 0.55
PEAK FLOW RATE(CFS) AT CONFLUENCE = 1.04
FLOW PROCESS FROM NODE 3.00 TO NODE 3.10 IS CODE = 21
»»>RATIONAL METHOD INITIAL SUBAREA ANALYSIS««<
*USER SPECIFIED(SUBAREA):
USER-SPECIFIED RUNOFF COEFFICIENT = .4000
S.C.S. CURVE NUMBER (AMC II) = 0
INITIAL SUBAREA FLOW-LENGTH(FEET) = 104.00
UPSTREAM ELEVATION(FEET) = 58.7 0
DOWNSTREAM ELEVATION(FEET) = 57.00
ELEVATION DIFFERENCE(FEET) = 1.7 0
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 9.538
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN
THE MAXIMUM OVERLAND FLOW LENGTH = 7 9.52
(Reference: Table 3-lB of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION!
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.343
SUBAREA RUNOFF(CFS) = 0.2 4
TOTAL AREA(ACRES) = 0.14 TOTAL RUNOFF(CFS) = 0.24
FLOW PROCESS FROM NODE 3.10 TO NODE 3.20 IS CODE = 52
»»>COMPUTE NATURAL VALLEY CHANNEL FLOW««<
»»>TRAVELTIME THRU SUBAREA««<
ELEVATION DATA: UPSTREAM(FEET) = 57.00 DOWNSTREAM(FEET) = 56.00
CHANNEL LENGTH THRU SUBAREA(FEET) = 77.00 CHANNEL SLOPE = 0.0130
NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION
CHANNEL FLOW THRU SUBAREA(CFS) = 0.2 4
FLOW VELOCITY(FEET/SEC) = 1.71 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL)
TRAVEL TIME(MIN.) = 0.75 Tc(MIN.) = 10.29
LONGEST FLOWPATH FROM NODE 3.00 TO NODE 3.20= 181.00 FEET.
FLOW PROCESS FROM NODE 3.20 TO NODE 3.20 IS CODE = 81
»»>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW««<
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.136
*USER SPECIFIED(SUBAREA):
USER-SPECIFIED RUNOFF COEFFICIENT = .4000
S.C.S. CURVE NUMBER (AMC II) = 0
AREA-AVERAGE RUNOFF COEFFICIENT = 0.4000
SUBAREA AREA(ACRES) = 0.06 SUBAREA RUNOFF(CFS) = 0.10
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TOTAL AREA(ACRES) = 0.2 TOTAL RUNOFF(CFS) = 0.33
TC(MIN.) = 10.29
FLOW PROCESS FROM NODE 3.20 TO NODE 4.00 IS CODE = 52
»>»COMPUTE NATURAL VALLEY CHANNEL FLOW««<
»>»TRAVELTIME THRU SUBAREA««<
ELEVATION DATA: UPSTREAM(FEET) = 56.00 DOWNSTREAM(FEET) = 50.30
CHANNEL LENGTH THRU SUBAREA(FEET) = 58.00 CHANNEL SLOPE = 0.0983
NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION
CHANNEL FLOW THRU SUBAREA(CFS) = 0.33
FLOW VELOCITY(FEET/SEC) = 4.70 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL)
TRAVEL TIME(MIN.) = 0.21 Tc(MIN.) = 10.49
LONGEST FLOWPATH FROM NODE 3.00 TO NODE 4.00 = 239.00 FEET.
FLOW PROCESS FROM NODE 4.00 TO NODE 4.00 IS CODE = 1
»»>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE««<
»>»AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES««<
TOTAL NUMBER OF STREAMS = 3
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 3 ARE:
TIME OF CONCENTRATION(MIN.) = 10.49
RAINFALL INTENSITY(INCH/HR) = 4.08
TOTAL STREAM AREA(ACRES) = 0.2 0
PEAK FLOW RATE(CFS) AT CONFLUENCE = 0.33
** CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 0.50 5.56 6.148 0.11
2 1.04 9.84 4.255 0.55
3 0.33 10.49 4.083 0.20
RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO
CONFLUENCE FORMULA USED FOR 3 STREAMS.
** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 1.26 5.56 6.148
2 1.70 9.84 4.255
3 1.66 10.49 4.083
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:
PEAK FLOW RATE(CFS) = 1.70 Tc(MIN.) = 9.84
TOTAL AREA(ACRES) = 0.9
LONGEST FLOWPATH FROM NODE 2.00 TO NODE 4.00= 241.00 FEET.
END OF STUDY SUMMARY:
TOTAL AREA(ACRES) = 0.9 TC(MIN.) = 9.84
PEAK FLOW RATE(CFS) = 1.7 0
*** PEAK FLOW RATE TABLE ***
Q(CFS) Tc(MIN.)
1 1.26 5.56
2 1.70 9.84
3 1.66 10.49
END OF RATIONAL METHOD ANALYSIS
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3.2 POSTDEVELOPED CONDITION HYDROLOGIC ANALYSIS
RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE
Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT
2003,1985,1981 HYDROLOGY MANUAL
(c) Copyright 1982-2008 Advanced Engineering Software (aes)
Ver. 15.0 Release Date: 04/01/2008 License ID 1452
Analysis prepared by:
+ + * -Jr *****-Jr ******* DESCRIPTION OF STUDY +•******•*••*•******•*•***•***** + *
* 100 YEAR STORM HYDROLOGIC ANALYSIS - DEVELOPED CONDITION *
* 2 01 WALNUT TOWNHOMES *
* PLSA 1939 - 03.01.13 * **************************************************************************
FILE NAME: 1939POST.DAT
TIME/DATE OF STUDY: 14:18 03/01/2013
USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION:
2 003 SAN DIEGO MANUAL CRITERIA
USER SPECIFIED STORM EVENT(YEAR) = 100.00
6-HOUR DURATION PRECIPITATION (INCHES) = 2.500
SPECIFIED MINIMUM PIPE SIZE(INCH) = 3.00
SPECIFIED PERCENT OF GRADIENTS(DECIIMAL) TO USE FOR FRICTION SLOPE = 0.95
SAN DIEGO HYDROLOGY MANUAL "C"-VALUES USED FOR RATIONAL METHOD
NOTE: CONSIDER ALL CONFLUENCE STREAM COMBINATIONS
FOR ALL DOWNSTREAM ANALYSES
*USER-DEFINED STREET-SECTIONS FOR COUPLED PIPEFLOW AND STREETFLOW MODEL*
HALF- CROWN TO STREET-CROSSFALL: CURB GUTTER-GEOMETRIES: MANNING
WIDTH CROSSFALL IN- / OUT-/PARK- HEIGHT WIDTH LIP HIKE FACTOR
NO. (FT) (FT) SIDE / SIDE/ WAY (FT) (FT) (FT) (FT) (n)
1 30.0 20.0 0.018/0.018/0.020 0.67 2.00 0.0313 0.167 0.0150
GLOBAL STREET FLOW-DEPTH CONSTRAINTS:
1. Relative Flow-Depth = 0.00 FEET
as (Maximum Allowable Street Flow Depth) - (Top-of-Curb)
2. (Depth)*(Velocity) Constraint = 6.0 (FT*FT/S)
*SIZE PIPE WITH A FLOW CAPACITY GREATER THAN
OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.*
****************************************************************************
FLOW PROCESS FROM NODE 1.00 TO NODE 1.10 IS CODE = 21
»»>RATIONAL METHOD INITIAL SUBAREA ANALYSIS««<
*USER SPECIFIED(SUBAREA):
USER-SPECIFIED RUNOFF COEFFICIENT = .6200
S.C.S. CURVE NUMBER (AMC II) = 0
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 55.50
DOWNSTREAM ELEVATION(FEET) = 54.00
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ELEVATION DIFFERENCE(FEET) = 1.50
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.427
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN
THE MAXIMUM OVERLAND FLOW LENGTH = 72.50
(Reference: Table 3-lB of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION!
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.602
SUBAREA RUNOFF(CFS) = 0.31
TOTAL AREA(ACRES) = 0.09 TOTAL RUNOFF(CFS) = 0.31
****************************************************************************
FLOW PROCESS FROM NODE 1.10 TO NODE 1.20 IS CODE = 52
»»>COMPUTE NATURAL VALLEY CHANNEL FLOW««<
»»>TRAVELTIME THRU SUBAREA««<
ELEVATION DATA: UPSTREAM(FEET) = 54.00 DOWNSTREAM(FEET) = 51.40
CHANNEL LENGTH THRU SUBAREA(FEET) = 133.00 CHANNEL SLOPE = 0.0195
NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION
CHANNEL FLOW THRU SUBAREA(CFS) = 0.31
FLOW VELOCITY(FEET/SEC) = 2.10 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL)
TRAVEL TIME(MIN.) = 1.06 Tc(MIN.) = 7.48
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 1.20 = 233.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 1.20 TO NODE 1.20 IS CODE = 81
»>»ADDITION OF SUBAREA TO MAINLINE PEAK FLOW««<
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.078
*USER SPECIFIED(SUBAREA):
USER-SPECIFIED RUNOFF COEFFICIENT = .6600
S.C.S. CURVE NUMBER (AMC II) = 0
AREA-AVERAGE RUNOFF COEFFICIENT = 0.6420
SUBAREA AREA(ACRES) = 0.11 SUBAREA RUNOFF(CFS) = 0.37
TOTAL AREA(ACRES) = 0.2 TOTAL RUNOFF(CFS) = 0.65
TC(MIN.) = 7.48
****************************************************************************
FLOW PROCESS FROM NODE 1.20 TO NODE 4.00 IS CODE = 62
»»>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA««<
»»> (STREET TABLE SECTION # 1 USED)««<
UPSTREAM ELEVATION(FEET) = 51.40 DOWNSTREAM ELEVATION(FEET) = 50.30
STREET LENGTH(FEET) = 137.00 CURB HEIGHT(INCHES) = 8.0
STREET HALFWIDTH(FEET) = 30.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 20.00
INSIDE STREET CROSSFALL(DECIMAL) = 0.018
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.018
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
STREET PARKWAY CROSSFALL(DECIMAL) = 0.020
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150
Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0200
**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 0.65
STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:
STREET FLOW DEPTH(FEET) = 0.2 5
HALFSTREET FLOOD WIDTH(FEET) = 4.78
AVERAGE FLOW VELOCITY(FEET/SEC.) = 1.64
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 0.41
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STREET FLOW TRAVEL TIME(MIN.) = 1.39 Tc(MIN.) = 8.88
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.54 9
AREA-AVERAGE RUNOFF COEFFICIENT = 0.642
SUBAREA AREA(ACRES) = 0.00 SUBAREA RUNOFF(CFS) = 0.00
TOTAL AREA(ACRES) = 0.2 PEAK FLOW RATE(CFS) = 0.65
END OF SUBAREA STREET FLOW HYDRAULICS:
DEPTH(FEET) = 0.2 5 HALFSTREET FLOOD WIDTH(FEET) = 4.7 8
FLOW VELOCITY(FEET/SEC.) = 1.64 DEPTH*VELOCITY(FT*FT/SEC.) = 0.41
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 4.00 = 370.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 4.00 TO NODE 4.00 IS CODE = 1
»»>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE««<
TOTAL NUMBER OF STREAMS = 3
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE:
TIME OF CONCENTRATION(MIN.) = 8.88
RAINFALL INTENSITY(INCH/HR) = 4.55
TOTAL STREAM AREA(ACRES) = 0.2 0
PEAK FLOW RATE(CFS) AT CONFLUENCE = 0.65
****************************************************************************
FLOW PROCESS FROM NODE 2.00 TO NODE 2.10 IS CODE = 21
»»>RATIONAL METHOD INITIAL SUBAREA ANALYSIS««<
*USER SPECIFIED(SUBAREA):
USER-SPECIFIED RUNOFF COEFFICIENT = .7300
S.C.S. CURVE NUMBER (AMC II) = 0
INITIAL SUBAREA FLOW-LENGTH(FEET) = 106.00
UPSTREAM ELEVATION(FEET) = 58.50
DOWNSTREAM ELEVATION(FEET) = 55.50
ELEVATION DIFFERENCE(FEET) = 3.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 4.425
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN
THE MAXIMUM OVERLAND FLOW LENGTH = 8 8.30
(Reference: Table 3-lB of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION!
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.587
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.
SUBAREA RUNOFF(CFS) = 0.14
TOTAL AREA(ACRES) = 0.03 TOTAL RUNOFF(CFS) = 0.14
****************************************************************************
FLOW PROCESS FROM NODE 2.10 TO NODE 2.20 IS CODE = 52
»»>COMPUTE NATURAL VALLEY CHANNEL FLOW««<
»»>TRAVELTIME THRU SUBAREA««<
ELEVATION DATA: UPSTREAM(FEET) = 55.50 DOWNSTREAM(FEET) = 50.60
CHANNEL LENGTH THRU SUBAREA(FEET) = 200.00 CHANNEL SLOPE = 0.0245
NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION
CHANNEL FLOW THRU SUBAREA(CFS) = 0.14
FLOW VELOCITY(FEET/SEC) = 2.35 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL)
TRAVEL TIME(MIN.) = 1.42 Tc(MIN.) = 5.84
LONGEST FLOWPATH FROM NODE 2.00 TO NODE 2.20 = 306.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 2.20 TO NODE 2.20 IS CODE = 81
>»»ADDITION OF SUBAREA TO MAINLINE PEAK FLOW««<
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100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.956
*USER SPECIFIED(SUBAREA):
USER-SPECIFIED RUNOFF COEFFICIENT = .6500
S.C.S. CURVE NUMBER (AMC II) = 0
AREA-AVERAGE RUNOFF COEFFICIENT = 0.6571
SUBAREA AREA(ACRES) = 0.31 SUBAREA RUNOFF(CFS) = 1.20
TOTAL AREA(ACRES) = 0.3 TOTAL RUNOFF(CFS) = 1.33
TC(MIN.) = 5.84
****************************************************************************
FLOW PROCESS FROM NODE 2.20 TO NODE 4.00 IS CODE = 62
»»>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA««<
»»>( STREET TABLE SECTION # 1 USED) ««<
UPSTREAM ELEVATION(FEET) = 50.60 DOWNSTREAM ELEVATION(FEET) = 50.30
STREET LENGTH(FEET) = 16.00 CURB HEIGHT(INCHES) = 8.0
STREET HALFWIDTH(FEET) = 30.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 20.00
INSIDE STREET CROSSFALL(DECIMAL) = 0.018
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.018
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
STREET PARKWAY CROSSFALL(DECIMAL) = 0.020
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150
Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0200
**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 1.33
STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:
STREET FLOW DEPTH(FEET) = 0.27
HALFSTREET FLOOD WIDTH(FEET) = 6.03
AVERAGE FLOW VELOCITY(FEET/SEC.) = 2.57
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 0.69
STREET FLOW TRAVEL TIME(MIN.) = 0.10 Tc(MIN.) = 5.95
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.889
AREA-AVERAGE RUNOFF COEFFICIENT = 0.657
SUBAREA AREA(ACRES) = 0.00 SUBAREA RUNOFF(CFS) = 0.00
TOTAL AREA(ACRES) = 0.3 PEAK FLOW RATE(CFS) = 1.33
END OF SUBAREA STREET FLOW HYDRAULICS:
DEPTH(FEET) = 0.27 HALFSTREET FLOOD WIDTH(FEET) = 6.03
FLOW VELOCITY(FEET/SEC.) = 2.57 DEPTH*VELOCITY(FT*FT/SEC.) = 0.69
LONGEST FLOWPATH FROM NODE 2.00 TO NODE 4.00 = 322.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 4.00 TO NODE 4.00 IS CODE = 1
»»>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE««<
TOTAL NUMBER OF STREAMS = 3
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 2 ARE:
TIME OF CONCENTRATION(MIN.) = 5.95
RAINFALL INTENSITY(INCH/HR) = 5.8 9
TOTAL STREAM AREA(ACRES) = 0.34
PEAK FLOW RATE(CFS) AT CONFLUENCE = 1.33
****************************************************************************
FLOW PROCESS FROM NODE 3.00 TO NODE 3.10 IS CODE = 21
»»>RATIONAL METHOD INITIAL SUBAREA ANALYSIS««<
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*USER SPECIFIED(SUBAREA):
USER-SPECIFIED RUNOFF COEFFICIENT = .7700
S.C.S. CURVE NUMBER (AMC II) = 0
INITIAL SUBAREA FLOW-LENGTH(FEET) = 99.00
UPSTREAM ELEVATION(FEET) = 58.50
DOWNSTREAM ELEVATION(FEET) = 57.30
ELEVATION DIFFERENCE(FEET) = 1.2 0
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 4.600
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN
THE MAXIMUM OVERLAND FLOW LENGTH = 68.18
(Reference: Table 3-lB of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION!
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.587
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.
SUBAREA RUNOFF(CFS) = 0.4 6
TOTAL AREA(ACRES) = 0.0 9 TOTAL RUNOFF(CFS) = 0.4 6
****************************************************************************
FLOW PROCESS FROM NODE 3.10 TO NODE 3.20 IS CODE = 52
»»>COMPUTE NATURAL VALLEY CHANNEL FLOW««<
»»>TRAVELTIME THRU SUBAREA««<
ELEVATION DATA: UPSTREAM(FEET) = 57.30 DOWNSTREAM(FEET) = 56.40
CHANNEL LENGTH THRU SUBAREA(FEET) = 112.00 CHANNEL SLOPE = 0.0080
NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION
CHANNEL FLOW THRU SUBAREA(CFS) = 0.46
FLOW VELOCITY(FEET/SEC) = 1.34 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL)
TRAVEL TIME(MIN.) = 1.39 Tc(MIN.) = 5.99
LONGEST FLOWPATH FROM NODE 3.00 TO NODE 3.20 = 211.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 3.20 TO NODE 3.20 IS CODE = 81
»»>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW««<
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.8 63
*USER SPECIFIED(SUBAREA):
USER-SPECIFIED RUNOFF COEFFICIENT = .4400
S.C.S. CURVE NUMBER (AMC II) = 0
AREA-AVERAGE RUNOFF COEFFICIENT = 0.5885
SUBAREA AREA(ACRES) = 0.11 SUBAREA RUNOFF(CFS) = 0.28
TOTAL AREA(ACRES) = 0.2 TOTAL RUNOFF(CFS) = 0.69
TC(MIN.) = 5.99
****************************************************************************
FLOW PROCESS FROM NODE 3.20 TO NODE 3.30 IS CODE = 62
»>»COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA««<
»»>(STREET TABLE SECTION # 1 USED) ««<
UPSTREAM ELEVATION(FEET) = 56.40 DOWNSTREAM ELEVATION(FEET) = 54.70
STREET LENGTH(FEET) = 4 4.00 CURB HEIGHT(INCHES) = 8.0
STREET HALFWIDTH(FEET) = 30.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 20.00
INSIDE STREET CROSSFALL(DECIMAL) = 0.018
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.018
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
STREET PARKWAY CROSSFALL(DECIMAL) = 0.020
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150
Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0200
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Preliminary Hydrology Study for Walnut Townhomes
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**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 0.69
STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:
STREET FLOW DEPTH(FEET) = 0.20
HALFSTREET FLOOD WIDTH(FEET) = 2.00
AVERAGE FLOW VELOCITY(FEET/SEC.) = 4.27
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 0.85
STREET FLOW TRAVEL TIME(MIN.) = 0.17 Tc(MIN.) = 6.16
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.757
AREA-AVERAGE RUNOFF COEFFICIENT = 0.58 9
SUBAREA AREA(ACRES) = 0.00 SUBAREA RUNOFF(CFS) = 0.00
TOTAL AREA(ACRES) = 0.2 PEAK FLOW RATE(CFS) = 0.69
END OF SUBAREA STREET FLOW HYDRAULICS:
DEPTH(FEET) = 0.20 HALFSTREET FLOOD WIDTH(FEET) = 2.00
FLOW VELOCITY(FEET/SEC.) = 4.27 DEPTH*VELOCITY(FT*FT/SEC.) = 0.85
LONGEST FLOWPATH FROM NODE 3.00 TO NODE 3.30 = 255.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 3.30 TO NODE 3.30 IS CODE = 81
»»>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW««<
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.757
*USER SPECIFIED(SUBAREA):
USER-SPECIFIED RUNOFF COEFFICIENT = .7100
S.C.S. CURVE NUMBER (AMC II) = 0
AREA-AVERAGE RUNOFF COEFFICIENT = 0.6165
SUBAREA AREA(ACRES) = 0.06 SUBAREA RUNOFF(CFS) = 0.25
TOTAL AREA(ACRES) = 0.3 TOTAL RUNOFF(CFS) = 0.92
TC(MIN.) = 6.16
****************************************************************************
FLOW PROCESS FROM NODE 3.30 TO NODE 3.40 IS CODE = 62
»»>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA««<
»»> (STREET TABLE SECTION # 1 USED) ««<
UPSTREAM ELEVATION(FEET) = 54.70 DOWNSTREAM ELEVATION(FEET) = 52.10
STREET LENGTH(FEET) = 54.00 CURB HEIGHT(INCHES) = 8.0
STREET HALFWIDTH(FEET) = 30.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 20.00
INSIDE STREET CROSSFALL(DECIMAL) = 0.018
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.018
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
STREET PARKWAY CROSSFALL(DECIMAL) = 0.020
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150
Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0200
**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 0.92
STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:
STREET FLOW DEPTH(FEET) = 0.20
HALFSTREET FLOOD WIDTH(FEET) = 2.00
AVERAGE FLOW VELOCITY(FEET/SEC.) = 4.76
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 0.94
STREET FLOW TRAVEL TIME(MIN.) = 0.19 Tc(MIN.) = 6.35
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.64 6
AREA-AVERAGE RUNOFF COEFFICIENT = 0.617
SUBAREA AREA(ACRES) = 0.00 SUBAREA RUNOFF(CFS) = 0.00
TOTAL AREA(ACRES) = 0.3 PEAK FLOW RATE(CFS) = 0.92
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PLSA1939
END OF SUBAREA STREET FLOW HYDRAULICS:
DEPTH(FEET) = 0.20 HALFSTREET FLOOD WIDTH(FEET) = 2.00
FLOW VELOCITY(FEET/SEC.) = 4.76 DEPTH*VELOCITY(FT*FT/SEC.) = 0.94
LONGEST FLOWPATH FROM NODE 3.00 TO NODE 3.40 = 309.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 3.40 TO NODE 3.40 IS CODE = 81
»»>ADDITION OF SUBAREA TO IMAINLINE PEAK FLOW««<
100 YEAR RAINFALL INTENSITY{INCH/HOUR) = 5.646
*USER SPECIFIED(SUBAREA):
USER-SPECIFIED RUNOFF COEFFICIENT = .6500
S.C.S. CURVE NUMBER (AMC II) = 0
AREA-AVERAGE RUNOFF COEFFICIENT = 0.6228
SUBAREA AREA(ACRES) = 0.06 SUBAREA RUNOFF(CFS) = 0.22
TOTAL AREA(ACRES) = 0.3 TOTAL RUNOFF{CFS) = 1.13
TC(MIN.) = 6.35
****************************************************************************
FLOW PROCESS FROM NODE 3.40 TO NODE 4.00 IS CODE = 62
»»>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA««<
»»> (STREET TABLE SECTION # 1 USED) ««<
UPSTREAM ELEVATION(FEET) = 52.10 DOWNSTREAM ELEVATION(FEET) = 50.30
STREET LENGTH(FEET) = 2 6.00 CURB HEIGHT(INCHES) = 8.0
STREET HALFWIDTH(FEET) = 30.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 20.00
INSIDE STREET CROSSFALL(DECIMAL) = 0.018
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.018
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
STREET PARKWAY CROSSFALL(DECIMAL) = 0.020
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150
Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0200
**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 1.13
STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:
STREET FLOW DEPTH(FEET) = 0.20
HALFSTREET FLOOD WIDTH(FEET) = 2.00
AVERAGE FLOW VELOCITY(FEET/SEC.) = 5.71
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 1.13
STREET FLOW TRAVEL TIME(MIN.) = 0.0 8 Tc(MIN.) = 6.4 3
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.603
AREA-AVERAGE RUNOFF COEFFICIENT = 0.623
SUBAREA AREA(ACRES) = 0.00 SUBAREA RUNOFF(CFS) = 0.00
TOTAL AREA(ACRES) = 0.3 PEAK FLOW RATE(CFS) = 1.13
END OF SUBAREA STREET FLOW HYDRAULICS:
DEPTH(FEET) = 0.20 HALFSTREET FLOOD WIDTH(FEET) = 2.00
FLOW VELOCITY(FEET/SEC.) = 5.71 DEPTH*VELOCITY(FT*FT/SEC.) = 1.13
LONGEST FLOWPATH FROM NODE 3.00 TO NODE 4.00 = 335.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 4.00 TO NODE 4.00 IS CODE = 1
»»>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE««<
»»>AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES««<
TOTAL NUMBER OF STREAMS = 3
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 3 ARE:
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Preliminary Hydrology Study for Walnut Townhomes
PLSA 1939
TIME OF CONCENTRATION(MIN.) = 6.43
RAINFALL INTENSITY(INCH/HR) = 5.60
TOTAL STREAM AREA(ACRES) = 0.32
PEAK FLOW RATE(CFS) AT CONFLUENCE = 1.13
CONFLUENCE DATA **
STREAM
NUMBER
1
2
3
RUNOFF
(CFS)
0.65
1.33
1.13
Tc
(MIN.
8.88
5. 95
6.43
INTENSITY
(INCH/HOUR)
4.549
5.889
5.603
AREA
(ACRE)
0.20
0.34
0.32
RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO
CONFLUENCE FORMULA USED FOR 3 STREAMS.
PEAK FLOW RATE TABLE *•*
STREAM
NUMBER
1
2
3
RUNOFF
(CFS)
2.81
2.86
2 . 59
Tc
(MIN.)
5. 95
6.43
INTENSITY
(INCH/HOUR)
5.889
5. 603
4 . 549
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:
PEAK FLOW RATE(CFS) = 2.8 6 Tc(MIN.) = 6.4 3
TOTAL AREA(ACRES) = 0.9
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 4.00 370.00 FEET.
END OF STUDY SUMMARY:
TOTAL AREA(ACRES)
PEAK FLOW RATE(CFS)
*** PEAK FLOW RATE TABLE
Q(CFS) Tc(MIN.)
1 2.81 5.95
2 2.86 6.43
3 2.59 8.88
0.9
2.86
TC(MIN. 6.43
END OF RATIONAL METHOD ANALYSIS
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Preliminary Hydrology Study for Walnut Townhomes
PLSA 1939
4.0 HYDRAULIC CALCULATIONS
7/25/2014
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Rational Method Hydrograph Calculations
for
201 Walnut, Carisbad, CA
Qioo" 1.7 cfs
Tc= 9.84 min 0= 0.45
#= 37 Pl00,6-2.5 in A= 0.9 acres
f7.44*P6*DV645; (fD/60) (V1-V0) (A V/A T) (Q=ciA) (Re-ordered)
D 1 VOL AVOL 1 (INCR) Q VOL ORDINATE
# (MIN) (IN/HR) (IN) (IN) (IN/HR) (CFS) (CF) (CFS)
0 0 0.00 0.00 0.70 4.28 1.70 1020
1 10 4.21 0.70 0.20 1.19 0.48 290 0.06
2 20 2.69 0.90 0.14 0.85 0.34 206 0.06
3 30 2.07 1.04 0.10 0.62 0.25 135 0.07
4 39 1.75 1.14 0.10 0.59 0.24 142 0.07
5 49 1.51 1.23 0.08 0.51 0.21 125 0.07
6 59 1.34 1.32 0.08 0.46 0.19 112 0.06
7 69 1.21 1.39 0.07 0.42 0.17 102 0.08
8 79 1.11 1.46 0.06 0.39 0.16 94 0.08
9 89 1.03 1.53 0.05 0.32 0.13 71 0.08
10 98 0.97 1.58 0.06 0.34 0.14 82 0.08
11 108 0.91 1.63 0.05 0.32 0.13 77 0.09
12 118 0.86 1.69 0.05 0.30 0.12 73 0.09
13 128 0.81 1.74 0.05 0.29 0.12 70 0.10
14 138 0.77 1.78 0.04 0.27 0.11 66 0.10
15 148 0.74 1.83 0.04 0.24 0.10 52 0.11
16 157 0.71 1.87 0.04 0.25 0.10 61 0.12
17 167 0.69 1.91 0.04 0.24 0.10 59 0.13
18 177 0.66 1.95 0.04 0.23 0.09 57 0.14
19 187 0.64 1.99 0.04 0.23 0.09 55 0.16
20 197 0.62 2.02 0.04 0.22 0.09 53 0.17
21 207 0.60 2.06 0.03 0.19 0.08 42 0.21
22 216 0.58 2.09 0.03 0.21 0.08 50 0.24
23 226 0.56 2.12 0.03 0.20 0.08 49 0.34
24 236 0.55 2.16 0.03 0.20 0.08 47 0.48
25 246 0.53 2.19 0.03 0.19 0.08 46 1.70
26 256 0.52 2.22 0.03 0.19 0.08 45 0.25
27 266 0.51 2.25 0.03 0.18 0.07 44 0.19
28 276 0.50 2.28 0.03 0.16 0.06 35 0.13
29 285 0.49 2.31 0.03 0.17 0.07 42 0.12
30 295 0.47 2.33 0.03 0.17 0.07 41 0.10
31 305 0.46 2.36 0.03 0.17 0.07 40 0.09
32 315 0.46 2.39 0.03 0.16 0.07 39 0.08
33 325 0.45 2.42 0.03 0.16 0.06 39 0.08
34 335 0.44 2.44 0.02 0.14 0.06 31 0.07
35 344 0.43 2.47 0.03 0.15 0.06 37 0.07
36 354 0.42 2.49 0.00 0.00 0.00 0 0.06
SUM= 3189
0.07
cubic feet
acre-feet
1939 Predeveloped Hydrograph (3-1-13) 7/25/2014
Rational Method Hydrograph Calculations
for
201 Walnut, Carlsbad, CA
Check: V = C*A*P6
V= 0.08 acre-feet
u
-4:80-
-4^
-i-;4e-
-+720-
-+:ee-
-OTSO-
-Orse-
-0:20-
-Oroe-
-40
RM-HYDROGRAPH
Project
110 160 210
Time (min)
260 310 360
1939 Predeveloped Hydrograph (3-1-13) 7/25/2014
Rational Method Hydrograph Calculations
for
201 Walnut, Carlsbad, CA
Qioo~ 2.86 cfs
Tc= 6.83 min C= 0.68
#= 53 Pl00,6~ 2.5 in A= 0.9 acres
(7.44*P6*D''-.645) (I'D/60) (V1-V0) (A V/A T) (Q=ciA) (Re-ordered)
D 1 VOL AVOL 1 (INCR) Q VOL ORDINATE
# (MIN) (IN/HR) (IN) (IN) (IN/HR) (CFS) (CF) (CFS)
0 0 0.00 0.00 0.62 5.43 2.86 1201
1 7 5.30 0.62 0.17 1.52 0.93 390 0.12
2 14 3.39 0.79 0.11 0.94 0.57 207 0.12
3 20 2.69 0.90 0.10 0.89 0.54 228 0.11
4 27 2.22 1.00 0.09 0.75 0.46 192 0.13
5 34 1.91 1.08 0.07 0.65 0.40 168 0.14
6 41 1.70 1.16 0.07 0.59 0.36 151 0.14
7 48 1.53 1.23 0.06 0.53 0.33 137 0.12
8 55 1.40 1.29 0.05 0.42 0.26 93 0.15
9 61 1.31 1.33 0.05 0.46 0.28 118 0.16
10 68 1.22 1.39 0.05 0.43 0.26 111 0.16
11 75 1.15 1.44 0.05 0.41 0.25 104 0.15
12 82 1.08 1.48 0.04 0.38 0.24 99 0.18
13 89 1.03 1.53 0.04 0.37 0.22 94 0.19
14 96 0.98 1.57 0.03 0.30 0.18 66 0.20
15 102 0.94 1.60 0.04 0.34 0.21 86 0.18
16 109 0.90 1.64 0.04 0.32 0.20 83 0.22
17 116 0.87 1.68 0.04 0.31 0.19 80 0.25
18 123 0.83 1.71 0.03 0.30 0.18 77 0.26
19 130 0.81 1.75 0.03 0.29 0.18 74 0.26
20 137 0.78 1.78 0.03 0.24 0.15 53 0.33
21 143 0.76 1.81 0.03 0.27 0.17 70 0.40
22 150 0.73 1.84 0.03 0.26 0.16 68 0.46
23 157 0.71 1.87 0.03 0.26 0.16 66 0.57
24 164 0.69 1.90 0.03 0.25 0.15 64 0.93
25 171 0.67 1.92 0.03 0.24 0.15 62 2.86
26 178 0.66 1.95 0.02 0.20 0.12 45 0.54
27 184 0.64 1.97 0.03 0.23 0.14 59 0.36
28 191 0.63 2.00 0.03 0.23 0.14 58 0.28
29 198 0.61 2.03 0.03 0.22 0.14 57 0.24
30 205 0.60 2.05 0.02 0.22 0.13 56 0.21
31 212 0.59 2.08 0.02 0.21 0.13 54 0.18
32 219 0.58 2.10 0.02 0.18 0.11 39 0.17
33 225 0.57 2.12 0.02 0.20 0.12 52 0.15
34 232 0.55 2.14 0.02 0.20 0.12 51 0.14
35 239 0.54 2.17 0.02 0.20 0.12 50 0.13
36 246 0.53 2.19 0.00 0.00 0.00 0 0.12
SUM= 4078
0.09
cubic feet
acre-feet
1939 Postdeveloped Hydrograph (3-1-13) 7/25/2014
Rational Method Hydrograph Calculations
for
201 Walnut, Carlsbad, CA
Check: V = C*A*P6
V= 0.13 acre-feet
3.50
3.00
2.50
2.00
J2 o
1.50
1.00
0.50
0.00
50
RM-HYDROGRAPH
Project
100 150
Time (min)
200 250
1939 Postdeveloped Hydrograph (3-1-13) 7/25/2014
Preliminary Hydrology Study for Walnut Townhomes
PLSA1939
5.0 APPENDIX
7/25/2014
23