HomeMy WebLinkAboutPD 2018-0006; DRAINAGE REPORT; 2018-06-12U
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DRAINAGE REPORT
3666 PlO PICO
ECONOLODGE 2-STORY EXPANSION
APN 205-191-09
CITY OF CARLSBAD
PROJECT NO, PD 2018-006
DWG. NO. 511-IA
Prepared for:
No. 29271
'\ Shas Management, Inc.
) . j 3666 Pio Pico Drive
CIVI Carlsbad, CA 92008
OF C
Prepared by:
bhA, Inc.
land planning, civil engineering, surveying
5115 Avenida Encinas, Suite L
Carlsbad, CA 92008-4387
RECF 1\TE (760) 931-8700
JUN 18 2018
LAND DEVELOPMENT June 12, 2018
ENGINEERING
W.O. 1060-1431-600
TABLE OF CONTENTS
Chapter 1 - Discussion ....................................................................................................................................... 3
1.1 Vicinity Map..................................................................................................................................3
1.2 Purpose and Scope........................................................................................................................4
1.3 Project Description.......................................................................................................................4
1.4 Pre-Development Conditions ......................................................................................................4
1.5 Post-Development Conditions ...................................................................................................... 5
1.6 Study Method ................................................................................................................................ 6
1.7 Conclusions....................................................................................................................................8
1.8 Declaration of Responsible Charge ............................................................................................9
Chapter 2— Existing & Developed Condition Hydrology Maps...................................................................10
Chapter 3 - Calculations..................................................................................................................................11
3.1 Existing Condition Hydrology Calculations..............................................................................11
100-Year Storm......................................................................................................................12
3.2 Developed Condition Hydrology Calculations.........................................................................14
100-Year Storm ...................................................................................................................... 15
Chapter 4 - References.....................................................................................................................................19
4.1 Methodology- Rational Method Peak Flow Determination...................................................19
DRAINAqE REPORT
3666 Pio Pico DRIVE CARLSbAd CA bliA, Inc
CHAPTER 1- DISCUSSION
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DRAiNAqE REPORT
3666 Pio Pico DRiVE, CARlsbAd, CA bliA, Inc.
1.2 PURPOSE AND SCOPE
The purpose of this report is to publish the results of hydrology and hydraulic computer
analysis for the proposed development of 3666 Pio Pico Drive, in the City of Carlsbad. The
scope of this study is to analyze the results of existing and developed condition hydrology
calculations and provide recommendations as to the design of small runoff collection
strategies. The mitigation measures proposed will include impervious area dispersion and
permeable material to minimize the transport of runoff to the storm drain system. The 100-
year storm frequency will be analyzed.
13 PROJECT DESCRIPTION
The project site is located at 3666 Pio Pico Drive in the City of Carlsbad (APN 205-191-09),
within A and developed residential neighborhood at the corner of Pio Pico Drive and
Magnolia Avenue, west of Interstate 5 Freeway. The project property consists of a parcel
of land, with mild slopes. The northerly portion of the project is occupied by existing
buildings and a parking lot that are to remain. The southerly portion of the project is vacant
and will be the site of expansion for a proposed two (2) story hotel with a parking lot. The
property consist of approximately 1.06 acres. The expansion portion of the property consist
of 0.22 acres.
Per County of San Diego drainage criteria, the Modified Rational Method should be used to
determine peak flow rates when the contributing drainage area is less than 1.0 square mile.
All storm water quality requi-rements for the project will be met by the source control and
site design BMPs (LID BMPs) intended to reduce the rate and volume of storm water runoff
and associated pollutant loads. See "Storm Water Standards Questionnaire Form E-34" and
"Standard Project Requirement Checklist Form E-36" prepared by BHA for low impact
development (LID) strategies throughout the project.
1.4 PRE-DEVELOPMENT CONDITIONS
Topographically, the project site drains westerly towards Pio Pico Drive. The vacant portion
of the parcel drains towards the southerly corner of Pio Pico Drive and Magnolia Avenue.
Developed residential lots neighbour the property on the east and south sides, with
apartments to the north, and Pio Pico Drive to the west. The existing site currently supports
two separate buildings and a parking lot with associated improvements. Outside of the
existing buildings, the property is occupied by a parking lot and grass-covered landscaping
with scattered bushes and trees. Excessive scouring or erosion is not present.
There are two storm drain inlets at the northeast corner of Pio Pico Avenue and Magnolia
Avenue located south of the property.
DRAINAqE REPORT
3666 Pio Pico DIVE, CARlsbAd, CA bhA, Inc.
Underlying hydrologic soil is Type B as determined from NRCS Web Soil Survey (see
Chapter 4 —References). Onsite soils areas have been assumed to be compacted in the
existing condition to represent the current condition of the site.
The following table summarizes the existing condition runoff information from the site.
Refer to the Existing Condition Hydrology Map for drainage patterns and areas.
TABLE 1—Summary of Existing Condition Peak Flow
100-Year Peak Flow Time of Discharge Location Drainage Area (Ac) (cfs) Concentration (mm)
Node 30 0.224 0.32 12.60
1.5 POST-DEVELOPMENT CONDITIONS
The project proposes the construction of a two (2) story hotel with a parking lot and
associated improvements. The disturbed area is approximately 0.22 acres. In the proposed
condition, approximately 50% of the improved site will be impervious.
The project also proposes improvements along Pio Pico Drive (replacing asphalt concrete
sidewalk with concrete) and Magnolia Avenue (constructing concrete driveway).
A point of discharge has been identified at the northeast corner of Pio Pico drive and
Magnolia Avenue where all runoff will be intercepted by two existing storm drain inlets.
The site will be separated into two drainage areas; one area draining south to Magnolia
Avenue (Node 30.1) and the other draining westerly towards Pio Pico Drive (Node 60).
Prior to discharging from the project site, developed site runoff from impervious areas such
as rooftops and walkways will be directed onto the surface of adjacent pervious areas, e.g.
permeable payers or landscaping. The intent is to slow runoff discharges and reduce
volumes while achieving incidental treatment. Runoff will then be intercepted by a catch
basin at Nodes 30, 30.1 and 60.
- Impervious surfaces have been minimized where feasible. Proposed grading is minimized
due to the previously mildly sloped pad. Proposed drainage patterns will not alter the
existing flow pattern and will discharge from the site to the historic discharge location.
Table 2 summarizes the expected cumulative 100-year peak flow rate from the developed
site. Refer to the Developed Condition Hydrology Map for drainage patterns and areas.
DRAiNAqE REPORT
3666Pio PICO DRIVE, CARLSbAd, CA bliA, Inc.
TABLE 2—Summary of Developed Condition Peak Flow
100-Year Peak Flow Time of Discharge Location Drainage Area (Ac)
(cfs) Concentration (mm)
Node 60 0.224 0.68 8.2 1
1.6 STUDY METHOD
The method of analysis was based on the Rational Method according to the San Diego
County Hydrology Manual (SD HM). The Hydrology and Hydraulic Analysis were done on
Hydro Soft by Advanced Engineering Software 2013. The study considers the runoff for a
100-year storm frequency.
Methodology used for the computation of design rainfall events, runoff coefficients, and
rainfall intensity values are consistent with criteria set forth in the "2003 County of San Diego
Drainage Design Manual." A more, detailed explanation of methodology used for this
analysis is listed in Chapter 4 References of this report.
Drainage basin areas were determined from the topography and proposed grades shown on
the Grading Plan for this site and County of San Diego 200-Scale Topography Maps.
The Rational Method for this project provided the following variable coefficients:
Rainfall Intensity - Initial time of concentration (Ta) values based on Table 3-2 of the SD
HM. Rainfall Isopluvial Maps from the SD HM were used to determine P6 for 100-year
storm, see References.
The design storm pattern is based on the County of San Diego Intensity-Duration Design
Chart. The chart uses the following equation to relate the intensity (I) of the storm to the
time of concentration (Tc):
I = 7.44x(P6)x(T) 0.645
P6 for 100-year storm =2.66"
Soil Type - The site was modeled with Type-13 hydrologic soil as determined from the NRCS
Web Soil Survey. Type-13 soils have moderate infiltration rates when thoroughly wetted.
Runoff Coefficient - In accordance with the County of San Diego standards, runoff
coefficients were based on land use and soil type. The soil conditions used in this study are
consistent with Type-13 soil qualities. An appropriate runoff coefficient (C) for each type of
land use in the subarea was selected from Table 3-1 of SD HM and multiplied by the
DRAiNAqE REPORT
1)
percentage of total area (A) included in that class. The sum of the products for all land uses
is the weighted runoff coefficient ([CA]).
Table 3 summarizes the composite C-values calculated in the existing and proposed
conditions.
TABLE 3—Weighted Runoff Coefficient Calculations
Existing Hydrology
Up Node Down Node Total Area (ac) Pervious C1 A, (ac)
Impervious
C2 A2 (ac) Ccomp
10 20 0.100 0.32 0.096 0.87 0.004 0.34
20 30 0.124 0.32 0.102 0.87 0.021 0.41
Note: C-values taken from Table 3-1 of San Diego County Hydrology Manual, consistent with on-site existing soil
types. See References.
Proposed Hydrology
Up Node Down Node Total Area (ac)
Pervious/
Premeable
Payers C1 A, (ac)C2
Impervious
A2 (ac) Ccomp
10 20 0.042 0.35 0.029 0.87 0.014 0.52
20 30 0.062 0.35 0.043 0.87 0.019 0.51
30.1 30.1 0.008 0.35 0.002 0.87 0.006 0.74
40 50 0.024 0.35 0.004 0.87 0.020 0.77
50 60 0.087 0.35 0.040 0.87 0.047 1 0.63
Note: C-values taken from Table 3-1 of San Diego County Hydrology Manual, consistent with on-site existing soil
types. See References.
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DRAINAqE REPORT
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1.7 CONCLUSION
Table 4 below summarizes the existing and developed condition drainage areas and resultant
100-year peak flow rates at the discharge location from the project site.
TABLE 4—Summary of 100-Year Peak Flows
Drainage Area 100-Year Peak Flow
(acres) (cfs)
Pre-Developed 0.224 0.32 Condition
Post- Developed 0.224 0.68
Condition
DIFFERENCE ] 0.000 0.36
As shown in Table 4, the development of the proposed 3666 Pio Pico Drive project site will
result in a net increase of peak flow discharged from the project site by approximately 0.36
cfs. This increase is considered negligible to the overall drainage discharged into the public
storm drain downstream at the northeast street intersection of Pio Pico Drive and Magnolia
Avenue. The project is part of the Basin B - Agua Hedionda Creek Watershed as described
in the Carlsbad Drainage Master Plan, dated July 3, 2008, where the watershed is stated to
be 19 square miles (12,160 acres). The improved project site area of 0.224 acres is 0.002%
of the total watershed area.
The design of pervious areas (landscaping and permeable payers) to effectively receive,
infiltrate and retain runoff from impervious surfaces will further mitigate runoff discharges
and reduce volumes. These small collection techniques foster opportunities to maintain the
natural hydrology and provide a much greater range of retention and detention practices.
The developed site will also implement source control and site design BMPs in accordance
with the "Standard Project Requirement Checklist Form E-36.
Peak flow rates listed above were generated based on criteria set forth in "San Diego County
Hydrology Manual" (methodology presented in Chapter 4 of this report). Rational method
output is located in Chapter 3. The hydraulic calculations show that the proposed onsite
storm drain facilities can sufficiently convey the anticipated Q1C3 flowrate without any adverse
effects. Based on this conclusion, runoff released from the proposed project site will be
unlikely to cause any adverse impact to downstream water bodies or existing habitat integrity.
Sediment will likely be reduced upon site development.
DRAINAqE REPORT
3666 Pio Pico DRIVE, CARlsbAd, CA bliA, Inc.
1.8 DECLARATION OF RESPONSIBLE CHARGE
— 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.
I understand that the check of project drawings and specifications by the City of Carlsbad is
confined to a review only and does not relieve me, as Engineer of Work, of my responsibilities
- for project design.
-
Ronald Holloway Date
R.C.E. 29271
DRAiNAqE REPORT
3666 Pio Pico DRIVE CARkbAd CA
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bhA. Inc
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CHAPTER 2
EXISTING & DEVELOPED CONDITION HYDROLOGY MAPS
I DRAINAqE REPORT
3666 Pic, Pico DRIVE, CARlsbAd, CA bl-iA, Inc.
CHAPTER 3
CALCULATIONS
3.1 - Existing Condition Hydrology Calculations
DRAINAqE REPORT
3666 Plo Pico DRIVE, CARlsbAd, CA bi-tA, Inc.
100-YEAR STORM
RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE
Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT
2003,1985,1981 HYDROLOGY MANUAL
(C) Copyright 1982-2014 Advanced Engineering Software (aes)
Ver. 21.0 Release Date: 06/01/2014 License ID 1459
Analysis prepared by:
BRA INC.
5115 AVENIDA ENCINAS, SUITE L
CARLSBAD, CA 92008
I
************************** DESCRIPTION OF STUDY **************************
* EXISTING HYDROLOGY
*
*
FILE NAME: K:\HYDRO\1431\431E100.DAT
TIME/DATE OF STUDY: 10:16 06/12/2018 ----------------------------------------------------------------------------
USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION: ----------------------------------------------------------------------------
2003 SAN DIEGO MANUAL CRITERIA
USER SPECIFIED STORM EVENT(YEAR) = 100.00
6-HOUR DURATION PRECIPITATION (INCHES) = 2.660
SPECIFIED MINIMUM PIPE SIZE(INCH) = 4.00
SPECIFIED PERCENT OF GRADENTS(DECIMAL) TO USE FOR FRICTION SLOPE = 0.90
SAN DIEGO HYDROLOGY MANUAL "C"-VALUES USED FOR RATIONAL METHOD
NOTE: USE MODIFIED RATIONAL METHOD PROCEDURES FOR CONFLUENCE ANALYSIS
*USER_D'INED STREET-SECT:ONS 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. (ET) (FT) SIDE / SIDE! WAY (FT) (FT) (FT) (FT) (n)
1 30.3 20.0 0.018/0.018/0.020 0.67 2.00 0.0312 0.167 0.0150
GLOBAL STREET FLOW-DEPTH CONSTRAINTS:
Relative Flow-Depth = 0.00 FEET
as (Maximum Allowable Street Flow Depth) - (Top-of-Curb)
(Depth)*(Velocity) Constraint = 6.0 (FT*FT!S)
*SIZE PI?E WITH A FLOW CAPACITY GREATER THAN
OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.*
********** k***************************************************************
FLOW PROCESS FROM NODE 10.00 TO NODE 20.00 IS CODE = 21 ----------------------------------------------------------------------------
>>>>>RAT tONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
*USER SPICIFIED(SUBAREA):
RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT = .3400
S.C.S. TTJRVE NUMBER (AMC II) = 0
INITIAL SUBAREA FLOW-LENGTH(FEET) = 65.00
UPSTREAM ELEVATION(FEET) = 74.20
DOWNSTREAM ELEVATION(FEET = 73.40
ELEVATION DIFFERENCE(FEET = 0.80
DRAINAqE REPORT
3666 Pio Pico DRIVE, CARkbAd, CA bIlA, Inc.
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 10.292
100 YEAR RAINFALL INTENSTY(INCH/HOUR) = 4.399
SUBAREA RUNOFF(CFS) = 0.15
TOTAL AREA(ACRES) = 0.10 TOTAL RUNOFF(CFS) = 0.15
FLOW PROCESS FROM NODE 20.00 TO NODE 30.00 IS CODE = 51 ----------------------------------------------------------------------------
>>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<< ----------------
ELEVATION DATA: UPSTREAM(FEET) = 73.40 DOWNSTREAM(FEET) = 72.12
CHANNEL LENGTH THRU SUBAREA(FEET) = 61.00 CHANNEL SLOPE = 0.0210
CHANNEL BASE(FEET) = 30.00 "Z" FACTOR = 50.000
MANNING'S FACTOR = 0.025 MAXIMUM DEPTH(FEET) = 1.00
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.864
*USER SPECIFIED(SUBAREA):
RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT = .4100
S.C.S. CURVE NUMBER (AMC II) = 0
TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 0.25
TRAVEL TIME THRU SUBAREA EASED ON VELOCITY(FEET/SEC.) = 0.44
AVERAGE FLOW DEPTH(FEET) = 0.02 TRAVEL TIME(MIN.) = 2.29
Tc(MIN.) = 12.59
SUBAREA AREA(ACRES) = 0.12 SUBAREA RUNOFF(CFS) = 0.19
AREA-AVERAGE RUNOFF COEFFICIENT = 0.378
TOTAL AREA(ACRES) = 0.2 PEAK FLOW RATE(CFS) = 0.32
END OF SUBAREA CHANNEL FLCW HYDRAULICS:
DEPTH(FEET) = 0'.02 FLOW VELOCITY(FEET/SEC.) = 0.57
LONGEST FLOWPATH FROM NODE 10.00 TO NODE 30.00 = 126.00 FEET.
END OF STUDY SUMMARY:
TOTAL AREA(ACRES) = 0.2 TC(MIN.) = 12.59
PEAK FLOW RATE (CFS) = 0.32
END OF RATIONAL' METHOD ANALYSIS
DRAINAqE REPORT
5666 Pic, Pico DRIVE, CARlsbAd, CA
_
Inc. 13
CHAPTER 3
CALCULATIONS
3.2 - Developed Condition Hydrology Calculations
DRAINAqE REPORT
3666 Pio Pico DRiVE, CARLSbAd, CA bhA, ____rm
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100-YEAR STORM
RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE
Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT
2003,1985,1981 HYDROLOGY MANUAL
:c) Copyright 1982-2014 Advanced Engineering Software (aes)
Ver. 21.0 Release Date: 06/01/2014 License ID 1459
Analysis prepared by:
BHA INC.
5115 AVENIDA ENCINAS, SUITE L
CARLSBAD, CA 92008
** *** DESCRIPTION OF STUDY kk ******* ******* ***** **
* PROPOSED HYDROLOGY
* *
* *
***** ***************************** * ******************** ***** *** ********* **
FILE NAME: K:\HYDRO\1431\1431P100.DAT
TIME/DATE OF STUDY: 15:51 06/12/2018
USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION: ----------------------------------------------------------
2003 SAN DIEGO MANUAL CRITERIA
USER SPECIFIED STORM EVENT(YEAR) = 100.00
6-HOUR DURATION PRECIPITATION (INCHES) = 2.660
SPECIFIED MINIMUM PIPE SIZE(INCH) = 4.00
SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE = 0.90
SAN DIEGO HYDROLOGY MANUAL "C"-VALUES USED FOR RATIONAL METHOD
NOTE: USE MODIFIED RATIONAL METHOD PROCEDURES FOR CONFLUENCE ANALYSIS
*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 0.0312 0.167 0.0150
GLOBAL STREET FLOW-DEPTH CONSTRAINTS:
Relative Flow-Depth = 0.00 FEET
as (Maximum Allowable Street Flow Depth) - (Top-of-Curb)
(Deph)*(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 10.00 TO NODE 20.00 IS CODE = 21 ----------------------------------------------------------------------------
>>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
*USER SPECIFIED(SUBAREA):
RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT = .5200
S.C.S. CURVE NUMBER (AMC II) = 0
INITIAL SUBAREA FLOW-LENGTH(FEET) = 50.00
UPSTREAM ELEVATION(FEET) = 73.80
DOWNSTREAM ELEVATION(FEET) = 73.15
ELEVATION DIFFERENCE(FEET) = 0.65
DRAINAqE REPORT
3666 Plo Pico DRIVE, C\RlsbAd, CA bhA. Inc.
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SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.764
100 YEAR RAINFALL INTENSTY(INCH/HOUR) = 5.767
SUBAREA RUNOFF(CFS) = 0.13
TOTAL AREA(ACRES) = 0.04 TOTAL RUNOFF(CFS) = 0.13
FLOW PROCESS FROM NODE 20.00 TO NODE 30.00 IS CODE = 51 ----------------------------------------------------------------------------
>>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<<
ELEVATION DATA: UPSTREAM(FEET) = 73.15 DOWNSTREAM(FEET) = 72.70
CHANNEL LENGTH THRU SUBAREA(FEET) = 78.00 CHANNEL SLOPE = 0.0058
CHANNEL BASE(FEET) = 0.00 "Z" FACTOR = 20.000
MANNING'S FACTOR = 0.015 MAXIMUM DEPTH(FEET) = 1.00
100 YEAR RAINFALL INTENS1TY(INCH/HOUR) = 5.148
*USER SPECIFIED(SUBAREA):
RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT = .5100
S.C.S. CURVE NUMBER (AMC I) = 0
TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 0.21
TRAVEL TIME THRU SUBAREA EASED ON VELOCITY(FEET/SEC.) = 1.00
AVERAGE FLOW DEPTH(FEET) = 0.10 TRAVEL TIME(MIN.) = 1.30
Tc(MIN.) = 8.07
SUBAREA AREA(ACRES) = 0.06 SUBAREA RUNOFF(CFS) = 0.16
AREA-AVERAGE RUNOFF COEFFICIENT = 0.514
TOTAL AREA(ACRES) = 0.1 PEAK FLOW RATE(CFS) = 0.28
END OF SUBAREA CHANNEL FLOW HYDRAULICS:
DEPTH(FEET) = 0.11 FLOW VELOCITY(FEET/SEC.) = 1.11
LONGEST FLOWPATH FROM NODE 10.00 TO NODE 30.00 = 128.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 30.00 TO NODE 30.10 IS CODE = 41
>>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING USER-SPECIFIED PIPESIZE (EXISTING ELEMENT)<<<<<
ELEVATION DATA: UPSTREAM(FEET) = 71.36 DOWNSTREAM(FEET) = 69.20
FLOW LENGTH(FEET) = 28.50 MANNING'S N = 0.013
DEPTH OF FLOW IN 4.0 INCH PIPE IS 2.1 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 5.88
GIVEN PIPE DIAMETER(INCH) = 4.00 NUMBER OF PIPES = 1
PIPE-FLOW(CFS) = 0.28
PIPE TRAVEL TIME(MIN.) = 0.08 Tc(NIN.) = 8.15
LONGEST FLOMPATH FROM NODE 10.00 TO NODE 30.10 = 156.50 FEET.
****************************************************************************
-
FLOW PROCESS FROM NODE 30.10 TO NODE 30.10 IS CODE = 81 ----------------------------------------------------------------------------
>>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.115
*USER SPECIFIED(SUBAREA):
RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT = .7400
S.C.S. CURVE NUMBER (AMC II) = 0
AREA-AVERAGE RUNOFF COEFFICIENT = 0.5320
SUBAREA AREA(ACRES) = 0.01 SUBAREA RUNOFF(CFS) = 0.03
TOTAL AREA(ACRES) = 0.1 TOTAL RUNOFF(CFS) = 0.31
TC(MIN.) = 8.15
FLOW PROCESS FROM NODE 30.10 TO NODE 60.00 IS CODE = 1
DRAINAqE REPORT
3666 Pic, Pico DRIVE, CARlSbAd, CA bhA. Inc.
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>>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<<
TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE:
TIME OF CONCENTRATION(MIN.) = 8.15
RAINFALL INTENSITY(INCH/HE) = 5.11
TOTAL STREAM AREA(ACRES) = 0.11
PEAK FLOW RATE(CFS) AT CONFLUENCE = 0.31
**************************** ************************************************
FLOW PROCESS FROM NODE 40.00 TO NODE 50.00 IS CODE = 21 ----------------------------------------------------------------------------
>>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
*USER SPECIFIED(SUBAREA):
RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT = .7700
S.C.S. CURVE NUMBER (AMC II) = 0
INITIAL SUBAREA FLOW-LENGTH(FEET) = 60.00
UPSTREAM ELEVATION(FEET) = 74.10
DOWNSTREAM ELEVATION(FEET) = 72.90
ELEVATION DIFFERENCE(FEET) = 1.20
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 3.652
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 7.008
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.
SUBAREA RUNOFF(CFS) = 0.13
TOTAL AREA(ACRES) = 0.02 TOTAL RUNOFF(CFS) = 0.13
****************************************************************************
FLOW PROCESS FROM NODE 50.00 TO NODE 60.00 IS CODE = 61 ----------------------------------------------------------------------------
>>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STANDARD CURB SECTICN USED)<<<<<
UPSTREAM ELEVATION(FEET) = 72.90 DOWNSTREAM ELEVATION(FEET I = 72.10
STREET LENGTH(FEET) = 80.00 CURB HEIGHT(INCHES) = 6.0
STREET HALFWIDTH(FEET) = 20.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 1.00
INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
STREET PARKWAY CROSSFALL(DECIMAL) = 0.020
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb = 0.0140
Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0200
**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 0.32
STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:
STREET FLOW DEPTH(FEET) = 0.18
HALFSTREET FLOOD WIDTH(FEET) = 2.63
AVERAGE FLOW VELOCITY(FET/SEC.) = 1.72
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 0.31
STREET FLOW TRAVEL TIME(MIN.) = 0.78 Tc(MIN.) = 4.43
100 YEAR RAINFALL INTENSIIY(INCH/HOUR) = 7.008
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.
*USER SPECIFIED(SUBAREA):
RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT = .6300
S.C.S. CURVE NUMBER (AMC II) = 0
AREA-AVERAGE RUNOFF COEFFICIENT = 0.660
SUBAREA AREA(ACRES) = 0.09 SUBAREA RUNOFF(CFS) = 0.38
TOTAL AREA(ACRES) = 0.1 PEAK FLOW RATE(CFS) = 0.51
DRAINAqE REPORT
3666 Pio Pico DRIVE, CARkbAd,CA bhA. Inc.
END OF SUBAREA STREET FLOW HYDRAULICS:
DEPTH(FEET) = 0.21 HALFTREET FLOOD WIDTH(FEET) = 4.20
FLOW VELOCITY(FEET/SEC.) = 1.74 DEPTH*VELOCITY(FT*FT/SEC.) = 0.37
LONGEST FLOWPATH FROM NODE 40.00 TO NODE 60.00 = 140.00 FEET.
*********** *****************************************************************
FLOW PROCESS FROM NODE 50.00 TO NODE 60.00 IS CODE = 1 ----------------------------------------------------------------------------
>>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<<
>>>>>AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES<<<<<
- TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 2 ARE:
TIME OF CONCENTRATION(MIN.) = 4.43
RAINFALL INTENSITY(INCH/HR) = 7.01
TOTAL STREAM AREA(ACRES) = 0.11
PEAK FLOW RATE(CFS) AT CONFLUENCE = 0.51
** CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 0.31 8.15 5.115 0.11
2 0.51 4.43 7.008 0.11
RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO
CONFLUENCE FORMULA USED FOR 2 STREAMS.
** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CE'S) (MIN.) (INCH/HOUR)
1 0.68 4.43 7.008
2 0.68 8.15 5.115
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:
PEAK FLOW RATE(CFS) = 0.68 Tc(MIN.) = 8.15
TOTAL AREA(ACRES) = 0.2
LONGEST FLOWPATH FROM NODE 10.00 TO NODE 60.00 = 156.50 FEET.
END OF STTJDY SUMMARY:
TOTAL AREA(ACRES) = 0.2 TC(MIN.) = 8.15
PEAK FLOW RATE(CFS) = 0.68
END OF RATIONAL METHOD ANALYSIS
DRAINAqE REPORT
3666 Rio Rico DRIVE, CARkbAd,CA bhA, inc.,,J--
CHAPTER 4
REFERENCES
4.1 - Methodology - Rational Method Peak Flow Determination
DRAiNAqE REPORT
3666P Pico DRivE, C[sbAd, CA bhA, Inc.
c County of San Diego
Hydrology Manua'
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Location name: Carlsbad, California, USA'
- Latitude: 33.1568, Loaitudo: .417.3376.'. \, r Elevation: 70.1606".
POINT PRECIPITAT1ON FREQUENCY ESTIMATES
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DRAINAqE REPORT
3666 Plo Pico DRIVE, CARLSbAd, CA bhA, Inc.
Precipitation Frequency Data Server Page 2 of 4
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DRAiNAqE REPORT
3666 Plo Pico DRiVE, CARkbAd, CA bhA, Inc.
___
3666 Plo Pico DRIVE, CARkbAdCA bi-IA, Inc.
Precipitation Frequency Data Server Page 4 of 4
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San Diego County Hydrology Manual Date: June 2003 Section: 3
Page:. 6of 26
Aj
Table 3-1
RUNOFF COEFFICIENTS FOR URBAN AREAS:
Soil Type
Undisturbed Natural Ten-am (Natural)
Low Density Residential (LOR)
Low Density Residential (LDR)
Low Density Residential (L.DR)
Medium Density Residential (MDR)
Medium Density Residential (MDR)
MediUm Density Residential (MDR)
Medium Density Residential (MDR)
High Density Resjcentjal (HDR)
High Density Residential (HDR)
Commercial/Industrial (N. Corn)
Commercial/Industrial (CL Corn)
Commercial/Industrial (O.P. Corn)
Commercial/industrial (Limited 1.)
Permanent Open Space 0 0.20 0.25 0.30
Residential, 1.0 DO/A Or less 10 0.27 0.32 0.36
Residential, 2.0 DO/A or less 20 0.34 038 042
Residential, 2.9 DO/A or less 25 0.38 :0.41 045
Residential, 4.3 DO/A or less .30 0.41 0.45 0,48
Residential, 73 DO/A or less 40 0.48 0.51 034
Residential, 10.9 DO/A or less 45 0.52 0.54 037
Residential, 14.5 DO/A or less 50 0.55 0.58 .0.60
Residential. 24.0 DO/A or less 65 0.66 0.67 0.69
Residential, 43.0 DU/A or less 80 0.16 0.77 0.78
Neighborhood Commercial 80 0.7,6 0.77 0.78
General Commercial 85 0.80 0.80 0.81
Office Professional/Commercial 90 0.83 0.84 0.84
Limited Industrial .90 043 0.84 0.84
General Industrial . 95 0.87 0.87 087
0.35
0.41
0.46
0.49
052
057
0.60
0.63
0.71
0.79
0.79
0.82
0.85
0.85
The values associated with 01/6 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 fore.ver(e.g., The area
is located in Cleveland National Forest).
DO/A = dwelling units per acre
NRCS =National Resources Conservation Service
3-6
San Diego County Hydrology Manual Section: 3 Date: June 2003 Page; 12 of 26
Note that the Initial Time of Concentration should be reflective of the general land-use at the
upstream end of a drainage basin. A.single.lot with an area of two or less acres does not have
a significant effect where the drainage basin..area is 20 to 600 acres.
Table 3-2 provides limits of the length (Maximum Length (LM)) of sheet flow to be used in
- bydroiogy.studies.. Initial Tivalues based on average C values for the Land Use Element are
also included. These; values can be used in planning and design applications as described
below. Exceptions may be approved by the "Regulating Agency" when submitted with a
detailed study.
MAXIMUM OVERLAND FLOW LENGTH (LM)
& INITIAL TIME OF CONCENTRATION (Tt'
Element* DUI
E!
.5% 1% 2% 3% 51010 10%
L Lm I JML Ti
Natural - 50113.2 70 12.5 85 10.9 100 10.3 100 8,7 100 6.9
LDR 1 50 122 70 115 85 100 1001 95 100 80 100 64
LtR 2 5 01 11.3 70 10.51 85 9.2 100 8.8 100 7.4 1 100 5.8
LDR 2.9 50110,7 70 10.0 85 8.8 95 8.1 100 7.01 100 5.6
MDR 4.3 501 10.2 70 9.6. 80 8,1 95 7,8 100 6.7 100 5.3
MDR. 7.3 501 9.2 65 8.4 80 7.4 .95 7.0 100 6.0 100 4.8
MDR 10.9 501 8.7 65 7.9 80 69 90 6.4 100 5.7 100 1 4.5
MDR 14.550.8.2657.4.806.5906,01005,41004,3
HDR 24 501 6.765.6.1 75 5.1 90 49 954.31003.5
HDR 43 50 53 65 4.7 75 4.0 85 .3.8 95 3.4 100 2.7
N. Corn 50 5.3 601 4.5 75 4.01 85 3.8 95 3.4 100 2.7
G. Cont 50 4.7 60 4.1 75 3.6 85 3.4 90 29 100 1 2.4
O.PJom 50 4.2 60 3;7 70 3.1 801 2.91 90 2.6 100 2.2
Limited 1. 1 50 4.2 60 3.7 70 3J 901 2.91 90 2.6 100 22
General 1.
1
50 3:7 60 32 70 2.7 80. 1 2.6 1 90 2.31 100 1.9
*See Table 3-1 for more detailed. description
3J2
DRAINAqE REPORT
3666 Plo Pico DRIVE, CARLSbAd, CA bkA, Inc
EQUATION
E u11.900.385
1Feot LE
(-5000 IC Time 01 concentration (Mows)
L Watercourse Distance (flflos) 4000 AE e change In elevation along
i- effective slope line (See Figure 3.5)(feet) —3000 Ic
L.,
Hours1 Minutes
240
—500
—400 'ye.
—300
—200
L Mites Foot
1—I
4000
18
15
so 0.5
40 ...2000
.1800 \ 1500 30 .1400
1200
20
Too
600
10 4
r00
AE L
- FIGURE
Nomograph for Determination of
Time of Concentration (To) or Travel Time (It) for Natural Wafsheds 3.4
DRAINAqE REPORT
3666 Pio Pico DrnVE, CARLSbAd, CA bIi, Inc. J 29
_1uI5!%
F I G U IL E
Gutter and Roadway Discharge - Velocity Chart
3-61]
bhA. Inc.
—
DRAINAqE REPORT
3666 Plo Pico DRIVE, CARLSbAd, CA
i ENIVAMIMUNNINNINVAbSONWAININ
A 4IIh.. AW1I
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-0.005
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IC 0,0006
0.0007
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0.0005
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2
EQUATIONV=j Ros n
0,5
0.15
0.0004
0.0003 L 20
SOURCE: USD01, FP4WA, HD6.3
GENERAL SOLUTION.
Mannings Equation Nomograph
'I G U RE
3..7]
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3666 Plo Pico DRIVE, CARlsbAd, CA bhA, Inc
Watershed Divide
'S
Watershed
Divide
Area "A"
-f-I
AE
Effective Slope Line Design Point
(Watershed Outlet)
Stream Profile
Area 'A" =Area IS.
SOURCE California Division and
PliGURE
Computation of Effective Slope for Natural Watersheds 3-5
DRAINAqE REPORT
3666 Pio Pico DRIVE, CARLSbAd, CA blIA, Inc. ____j 32 —