HomeMy WebLinkAboutTechnical Report 09 - Drainage ReportDRAINAGE STUDY
For
OTAY RANCH TOWN CENTER
City of Chula Vista, California
Prepared for:
Brookfield properties
733 Eighth Avenue
San Diego, CA 92101
W.O. 3553-0002
February 08th, 2023
Hunsaker & Associates
San Diego, Inc.
Alisa S. Vialpando, R.C.E. 47945
President
Otay Ranch Town Center
Drainage Study
TABLE OF CONTENTS
Page
Chapter 1 - Executive Summary
1.1 Introduction 1
1.2 Summary of Exiting Conditions 3
1.3 Summary of Developed Conditions 3
1.4 Results & Recommendations 5
1.5 References 7
Chapter 2 - Methodology & Model Development
2.1 Rational Method Model Development Summary
2.2 Design Rainfall Determination
2.3 Runoff Coefficient Determination
2.4 Rainfall Intensity Determination
Maximum Overland Flow Length & Initial Time of
Concentration Table
Urban Watershed Overland Time of Flow Nomograph
Gutter & Roadway Discharge-Velocity Chart
Manning’s Equation Nomograph
Intensity-Duration Design Chart
Chapter 3 - Hydrologic Analysis
3.1 50-Year Existing Condition AES Model Output
3.2 50-Year Developed Condition AES Model Output
3.3 100-Year Existing Condition AES Model Output
3.4 100-Year Developed Condition AES Model Output
Chapter 4 – Detention Basin Analysis
Chapter 5 – Preliminary Desilt Basin Calculations
Chapter 6 – Hydrology Exhibits/Maps
Existing Condition Hydrology Map (Exhibit 1)Map Pocket 1
Developed Condition Hydrology Map (Exhibit 2)Map Pocket 2
Overlay of Flood Insurance Rate Map (Exhibit 3)Map Pocket 3
Otay Ranch Town Center
Drainage Study
1
CHAPTER 1 - EXECUTIVE SUMMARY
1.1 Introduction
This drainage study has been prepared to assess the existing and re-developed condition
peak runoff rates from the proposed Otay Ranch Town Center development for Brookfield
Properties. Future drainage report will be prepared for the final engineering to design storm
drain system and inlets.
The project site is located in the eastern portion of the City of Chula Vista, California, within
the Otay Ranch General Development Plan (GDP) Area. More specifically, the site is
located immediately east of State Route 125 (SR-125) between Birch Road and Olympic
Parkway (See Vicinity Map below). The site is within the Sectional Planning Area (SPA)
known as the Freeway Commercial SPA.
The site in its exiting condition consists of surface parking, driveways, a temporary
recreation center and an open space.
The re-development will predominately consist of three residential buildings with maximum
of 840 residential units, associated streets, sidewalks and utility infrastructure.
The gross project area is approximately 16.59 acres including all high density residential ar-
eas. Due to the imperviousness increase associated with the development, it is anticipated
that peak flows generated from the site will increase runoff downstream unless measures
are made to mitigate the peak flows. These increases will need to be considered in the
projects design and are addressed in this study.
An underground storage vault will be installed to mitigate the peak flows and address flow
control (hydromodification) requirements for the re-developed portions of the site. All re-
impervious areas constructed throughout the site will route their 85th percentile runoff
through the MWS unit (proprietary biofiltration unit) BF-3-1 downstream of the storage vault.
A small portion north of 2nd Street, which drains Southerly, will route its 85th percentile
runoff through two flow-based MWS units (or equivalent) to address water quality
requirements for this portion before discharging into the bypass storm drain. The proposed
vault location is south of North Ave at the southwestern portion of the project site.
Otay Ranch Town Center
Drainage Study
2
Per the Flood Insurance Rate Map No. 06073C-1938G,1939G, 2176G and 2177G the site
lies outside the FEMA floodplain boundary. Therefore, a Letter of Map Revision is not
required. See Exhibit 3 for an overlay of the site on Flood Insurance Rate Map.
Per the City of Chula Vista drainage criteria, the Modified Rational Method can be used to
determine peak design flow rates when the contributing drainage area is less than 1.0-
square mile. Since the total watershed area discharging from the Otay Ranch Town Center
site is less than 1.0-square mile, the AES-2015 computer software was used to model the
runoff response per the Modified Rational Method.
Methodology used for the computation of design rainfall events, runoff coefficients, and
rainfall intensity values are consistent with criteria set forth in the most current “ “City of
Chula Vista Subdivision Manual”. A detailed explanation of methodology and model
development used for this analysis is listed in Chapter 2 of this report.
Otay Ranch Town Center
Drainage Study
3
1.2 Summary of Existing Conditions
In Existing condition, the Otay Ranch Town Center site generally flows in a southwesterly
direction to be picked up by inlets and catch basins. The collected runoff is routed via three
storm drain lines running from north to south to join off site of the redeveloped area and
discharge to a single connection point to the public storm drain system in Birch Road.
The storm water then is conveyed to the Poggi Canyon Detention Basin for peak storm
attenuation, which ultimately discharges into Otay River, 4.5 miles southwest of the study
area. Refer to Exhibit 1, Existing Hydrology Map in Chapter 5 for watershed boundary
associated with the project area. The watershed area delineated on the map was
determined as a means of equally comparing the impact of the proposed re-development
with its comparable existing condition at three connecting points to the existing storm drain.
Table 1 below summarizes the 100-year pre-development peak flows from the site in
existing condition. A runoff coefficient of 0.9, 0.65 and 0.3 per the City of Chula Vista
Subdivision Manual. These coefficients correspond respectfully paved area, barren slope
flat for the western open area, and parks for the temporary recreation area.
TABLE 1 - Summary of Pre-Developed Flows to the Poggi Canyon
Discharge
Location Node #
Drainage
Area
(ac)
100-Year
Peak
Flow
(cfs)
Tc (min)
Point of
Connection to the
western storm
drain
17 11.02 32.07 8.85
Point of
Connection to the
Central storm
drain
9 3.40 12.63 8.29
Point of
Connection to the
eastern storm
drain
12 2.93 10.94 8.76
Supporting calculations for the data presented in Table 1 are located in Chapter 3 of this
report. The corresponding hydrology map is Exhibit 1 in Chapter 9.
1.3 Summary of Developed Conditions
Runoff from the Otay Ranch Town Center in its re-developed condition will be collected
within the proposed storm drain system, which will rout the runoff to the proposed vault and
mitigate the peak flow to meet existing conditions and then connect to the existing storm
drain.
Otay Ranch Town Center
Drainage Study
4
See Exhibit 2, Proposed Condition Hydrology Map in Chapter 5. For water quality and
hydromodification discussion and calculations, please reference the Priority Development
Project (PDP) Storm Water Quality Management Plan (SWQMP) for Otay Ranch Town
Center dated February, 2022 prepared by Hunsaker & Associates San Diego Inc.
In general, runoff from the developed site will drain south towards North Ave. Inlets placed
throughout the site will collect the runoff and the storm drain will convey it towards the storm
drain system. This storm drain system will convey flows to the proposed vault located south
of North Ave.
Table 2 below summarizes the 100-year developed condition peak flows at the location of
the connecting points to the existing storm. Runoff coefficients assumed 0.9 for the paved
roads, 0.75 for dense residential per the City of Chula Vista Subdivision Manual.
TABLE 2 - Summary of Developed Flows to Otay River
Discharge
Location Node #
Drainage
Area
(ac)
100-Year
Peak
Flow
(cfs)
Tc (min)
Point of
Connection to the
western storm
drain
20 14.82 37.14 14.43
Point of
Connection to the
Central storm
drain
6 0.36 1.32 8.42
Point of
Connection to the
eastern storm
drain
23 2.20 8.08 9.29
Supporting calculations for the information presented in Table 2 is located in Chapter 3 and
4 of this report. The corresponding hydrology map is Exhibit 2 in Chapter 5.
Otay Ranch Town Center
Drainage Study
5
1.4 Results & Recommendations
Table 3 summarizes the effects of site development at the receiving Otay River.
TABLE 3 - Summary of Pre vs. Post-Developed Flows from Otay Town Center
*The collected runoff from the three storm drain lines discharge to a single connection point
to the public storm drain system in Birch Road.
Development of Otay Ranch Town Center results in the net decrease of runoff considering
the effect of the proposed detention vault.
Since the flows have been reduced for these subareas, existing flow velocities should not be
exceeded once the site has been developed. Therefore, erosion is not expected at the
downstream points of these subareas.
Summary:
Drainage facilities within the site will be designed in accordance with the
requirements of the Chula Vista Subdivision Manual, the San Diego County
Hydrology Manual and the requirements of the San Diego Regional Water Quality
Control Board.
PRE-DEVELOPED POST -DEVELOPED DIFFERENCE
Discharg
e
Location
Node
# Drainage
Area
(ac)
100-
Year
Peak
Flow
(cfs)
Node
#
Drainage
Area
(ac)
100-
Year
Peak
Flow
(cfs)
Area
(ac)
100-Year
Peak Flow
(cfs)
Point of
Connection
to the
western
storm drain
17 11.02 32.07 20 14.82
37.14
UNATT
21.62
ATT
+3.80 -10.45
Point of
Connection
to the
Central
storm drain
9 3.40 12.63 6 0.36 1.32 -3.04 -11.28
Point of
Connection
to the
eastern
storm drain
12 2.93 10.94 23 2.20 8.08 -0.73 -2.86
Total*17.35 55.64 17.38 32.79 0 -24.59
Otay Ranch Town Center
Drainage Study
6
Development of the project site will not further degrade potential beneficial uses of
downstream water bodies as designated by the Regional Water Quality Control
Board, including water bodies listed on the Clean Water Section 303d list.
References
City of Chula Vista Subdivision Manual; Engineering Department and Land Development;
Section 3-200, March 13, 2012
San Diego County Hydrology Manual; County of San Diego Department of Public Works
Flood Control Division, June 2003
Hydromodification Management Plan prepared for County of San Diego, California, March
2015
Priority Development Project (PDP) Storm Water Quality Management Plan (SWQMP) for
Otay Ranch Town Center prepared by Hunsaker and Associates, San Diego Inc.,
July 2022.
“Order No. R9-2013-0001, NPDES No. CAS0109266 – Waste Discharge Requirements for
Discharges of Urban Runoff from the Municipal Separate Storm Sewer Systems
(MS4s) Draining the Watersheds of the County of San Diego, the Incorporated Cities
of San Diego County, San Diego Unified Port District and the San Diego County
Regional Airport Authority”, California Regional Water Quality Control Board – San
Diego Region.
Otay Ranch Town Center
Drainage Study
7
CHAPTER 2 - METHODOLOGY
2.1 - Rational Method Model Development Summary
Computer Software Package – AES-2015
Design Storm – 50 -Year
Land Use – Multi Family
Soil Type - Hydrologic soil group D was assumed for all areas. Group D soils have very
slow infiltration rates when thoroughly wetted. Consisting chiefly of clay soils with a high
swelling potential, soils with a high permanent water table, soils with clay pan or clay layer at
or near the surface, and shallow soils over nearly impervious materials, Group D soils have
a very slow rate of water transmission.
Runoff Coefficient – In accordance with the City of Chula Vista Subdivision Manual, a runoff
coefficient of 0.90 was used for fully paved areas, 0.75 for the Multi-Family Sites and dense
residential, 0.65 for the barren slopes flat, 0.35 for proposed open space, and 0.30 for parks.
Method of Analysis – The Rational Method is the most widely used hydrologic model for
estimating peak runoff rates. Applied to small urban and semi-urban areas with drainage
areas less than 1.0 square mile, the Rational Method relates storm rainfall intensity, a runoff
coefficient, and drainage area to peak runoff rate. This relationship is expressed by the
equation:
Q = CIA, where:
Q = The peak runoff rate in cubic feet per second at the point of analysis.
C = A runoff coefficient representing the area - averaged ratio of runoff to rainfall intensity.
I = The time-averaged rainfall intensity in inches per hour corresponding to the time of
concentration.
A = The drainage basin area in acres.
To perform a node-link study, the total watershed area is divided into subareas which
discharge at designated nodes.
Otay Ranch Town Center
Drainage Study
8
The procedure for the subarea summation model is as follows:
(1)Subdivide the watershed into an initial subarea (generally 1 lot) and subsequent
subareas, which are generally less than 10 acres in size. Assign upstream and
downstream node numbers to each subarea.
(2)Estimate an initial Tc by using the appropriate nomograph or overland flow velocity
estimation.
(3)Using the initial Tc, determine the corresponding values of I. Then Q = C I A.
(4)Using Q, estimate the travel time between this node and the next by Manning’s
equation as applied to the particular channel or conduit linking the two nodes. Then,
repeat the calculation for Q based on the revised intensity (which is a function of the
revised time of concentration)
The nodes are joined together by links, which may be street gutter flows, drainage swales, drainage
ditches, pipe flow, or various channel flows. The AES-2010 computer subarea menu is as
follows:
SUBAREA HYDROLOGIC PROCESS
1.Confluence analysis at node.
2.Initial subarea analysis (including time of concentration calculation).
3.Pipeflow travel time (computer estimated).
4.Pipeflow travel time (user specified).
5.Trapezoidal channel travel time.
6.Street flow analysis through subarea.
7.User - specified information at node.
8.Addition of subarea runoff to main line.
9.V-gutter flow through area.
10. Copy main stream data to memory bank
11. Confluence main stream data with a memory bank
12. Clear a memory bank
At the confluence point of two or more basins, the following procedure is used to combine
peak flow rates to account for differences in the basin’s times of concentration. This
adjustment is based on the assumption that each basin’s hydrographs are triangular in
shape.
(1). If the collection streams have the same times of concentration, then the Q
values are directly summed,
Qp = Qa + Qb; Tp = Ta = Tb
Otay Ranch Town Center
Drainage Study
9
(2). If the collection streams have different times of concentration, the smaller of
the tributary Q values may be adjusted as follows:
(i).The most frequent case is where the collection stream with the longer
time of concentration has the larger Q. The smaller Q value is
adjusted by the ratio of rainfall intensities.
Qp = Qa + Qb (Ia/Ib); Tp = Ta
(ii). In some cases, the collection stream with the shorter time of
concentration has the larger Q. Then the smaller Q is adjusted by a
ratio of the T values.
Qp = Qb +Qa (Tb/Ta); Tp = Tb
CHAPTER 2
METHODOLOGY & MODEL DEVELOPMENT
2.2 – Design Rainfall Determination
50-Year, 6-Hour Rainfall Isopluvial Maps from
City of Chula Vista Design Standards – CVDS
Storm Drain Design
Otay Ranch Town Center
Drainage Study
CHAPTER 2
METHODOLOGY & MODEL DEVELOPMENT
2.3 – Runoff Coefficient Determination
Otay Ranch Town Center
Drainage Study
From To code total impervious
1 2 2 0.10 0.06 57.93%0.67 *
2 3 6 0.29 0.23 80.77%0.79 *
3 4 3 *
5 4 8 0.26 0.26 100.00%0.90 *
4 9 3
9 9 1
6 7 2 0.10 0.07 65.64%0.71 *
7 8 6 2.65 2.19 82.64%0.80 *
8 9 3
9 9 1
*
10 11 2 0.10 0.05 53.80%0.65 *
11 12 6 2.83 2.41 85.16%0.82
13 14 2 0.09 0.09 100.00%0.90
14 17 6 5.86 5.16 88.05%0.83 *
15 17 8 3.64 0.00%0.30 Park (temporary recreation area)
16 17 8 1.43 0.00%0.65 Baren Slope Flat
17.35 10.52 60.64%
*The runoff coeffecient for the subarea is a composite coeffecient made of the differnet runoff coefficients
for the surfaces of the subarea (0.9 for paved area, 0.3 for the landscaped area(park)) per equation:
C =( C1 x A1 + C2x A2 )/ A
Impervious 10.52
Total Area
AES INPUT DATA
Node #Area (ac)imperviousness C value
From To code total impervious
1 2 2 0.10 0.06 62.25%0.69 *
2 3 6 2.08 1.06 50.95%0.63 *
3 7.3 3
7 7.3 8 0.44 0.42 95.45%0.88
7.3 10 3
11 10 8 3.45 2.53 73.35%0.75 Dense Residential
10 12 3
12 12 1
8 9 2 0.06 0.04 73.21%0.75 *
9 12 6 0.81 0.63 77.89%0.78 *
12 12 1
12 14 3
13 14 8 2.66 1.88 70.67%0.75 Dense Residential
14 15 3
15 15 10
17 18 2 0.10 0.05 50.59%0.63 *
18 19 6 1.46 1.18 80.82%0.79 *
16 19 8 3.66 2.92 79.90%0.75 Dense Residential
19 15 3
15 15 11
15 15 12
15 20 3
14.82 10.78 72.76%0.7165 **
4 5 2 0.04 0.03 74.19%0.76 *
5 6 6 0.32 0.25 78.52%0.78 *
21 22 2 0.10 0.05 53.80%0.65 *
22 23 6 2.10 1.87 88.87%0.84 *
2.56 2.20 85.98%#REF!
17.38 13.93 70.84%
*The runoff coeffecient for the subarea is a composite coeffecient made of the differnet runoff coefficients
for the surfaces of the subarea (0.9 for paved area, 0.3 for the landscaped area(park)) per equation:
C =( C1 x A1 + C2x A2 )/ A
** Weighted C value = (Ci x Ai)/ tota A
Area to Vault
Total Area
Area not to vault
AES INPUT DATA
Node #Area (ac)imperviousness C value
Otay Ranch Town Center
Drainage Study
CHAPTER 2
METHODOLOGY & MODEL DEVELOPMENT
2.4 – Rainfall Intensity Determination
-Maximum Overland Flow Length & Initial Time
of Concentration
-Urban Watershed Overland Time of Flow
Nomograph
-Gutter & Roadway Discharge-Velocity Chart
- Manning’s Equation Nomograph
-Intensity-Duration Design Chart
F I G U R E
SOURCE: San Diego County Department of Special District Services Design Manual
3-6Gutter and Roadway Discharge - Velocity Chart
0.13
EXAMPLE:
Given: Q = 10 S = 2.5%
Chart gives: Depth = 0.4, Velocity = 4.4 f.p.s.
Depth RESIDENTIAL STREET
ONE SIDE ONLY
1.5’
n = .015
1 2 3 4 5 6 7 8 9 10 20 30 40 50
Discharge (C.F.S.)
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.2
1.4
1.6
1.8
2
3
6
4
5
7
8
9
10
12
14
16
18
20
V = 2.5 f.p.s.
V = 3 f.p.s.
V = 4 f.p.s.
V = 5 f.p.s.
V = 6 f.p.s.
V = 8 f.p.s.
V = 10 f.p.s.
V = 12 f.p.s.
V = 2 f.p.s.
Depth 0.7 Feet
Depth 0.6 Feet
Depth 0.5 Feet
Depth 0.4 FeetDepth 0.3 Feet
Depth 0.25 Feet
Depth 0.2 Feet
% of Street Slope
V = 1.5 f.p.s.
2%
2%
n = .0175
P a v e dConcrete
Gutter
F I G U R E
SOURCE: USDOT, FHWA, HDS-3 (1961)
3-7Manning’s Equation Nomograph
s =0 .0 0 3
n =0 .0 2
SLOPE in feet
per f
oot -s
HYDRAULIC
RADIUS
in f
eet
- R
VE
LO
CITY i
n feet
per
second -
V
E X A M P L E
R
=
0.6
V
=
2.9
EQUATION: V = ____ R2/3 s1/21.49
n
0.3
0.2
0.15
0.10
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0.009
0.008
0.007
0.006
0.005
0.004
0.003
0.002
0.0003
0.0004
0.0005
0.0006
0.0007
0.0008
0.0009
0.001
20
10
9
8
7
6
5
4
3
2
1.0
0.9
0.8
0.7
0.6
0.5
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
2
3
4
10
9
8
7
6
5
50
40
30
20
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.10
0.2
0.3
0.4
GENERAL SOLUTION
ROUGHNESS Coefficient - n
Otay Ranch Town Center
Drainage Study
CHAPTER 3
HYDROLOGIC ANALYSIS
3.1 – 50-Year Existing Condition
AES Model Output
50EX.OUT
____________________________________________________________________________
****************************************************************************
RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE
Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT
2003,1985,1981 HYDROLOGY MANUAL
(c) Copyright 1982-2015 Advanced Engineering Software (aes)
Ver. 22.0 Release Date: 07/01/2015 License ID 1239
Analysis prepared by:
Hunsaker & Associates San Diego, Inc.
9707 Waples Street
San Diego, CA 92121
************************** DESCRIPTION OF STUDY **************************
* Otay Ranch town Center *
* 50-Year return interval *
* DLN: 1643, w.O 3553-0002 *
**************************************************************************
FILE NAME: R:\1643\HYD\TM\DR\CALCS\AES\50\50EX.DAT
TIME/DATE OF STUDY: 09:44 02/10/2023
----------------------------------------------------------------------------
USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION:
----------------------------------------------------------------------------
2003 SAN DIEGO MANUAL CRITERIA
USER SPECIFIED STORM EVENT(YEAR) = 50.00
6-HOUR DURATION PRECIPITATION (INCHES) = 2.180
SPECIFIED MINIMUM PIPE SIZE(INCH) = 18.00
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 0.0313 0.167 0.0150
2 17.0 10.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.125 0.0150
3 20.0 12.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.125 0.0150
4 16.0 10.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.125 0.0150
5 26.0 18.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.125 0.0150
6 44.0 12.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.125 0.0150
7 12.0 7.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.125 0.0150
GLOBAL STREET FLOW-DEPTH CONSTRAINTS:
1. Relative Flow-Depth = 0.50 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 2.00 IS CODE = 21
----------------------------------------------------------------------------
>>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .6700
INITIAL SUBAREA FLOW-LENGTH(FEET) = 60.00
UPSTREAM ELEVATION(FEET) = 628.30
DOWNSTREAM ELEVATION(FEET) = 627.50
ELEVATION DIFFERENCE(FEET) = 0.80
URBAN SUBAREA OVERLAND TIME OF FLOW(MIN.) = 5.447
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.435
SUBAREA RUNOFF(CFS) = 0.36
TOTAL AREA(ACRES) = 0.10 TOTAL RUNOFF(CFS) = 0.36
Page 1
50EX.OUT
****************************************************************************
FLOW PROCESS FROM NODE 2.00 TO NODE 3.00 IS CODE = 62
----------------------------------------------------------------------------
>>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 5 USED)<<<<<
============================================================================
UPSTREAM ELEVATION(FEET) = 627.50 DOWNSTREAM ELEVATION(FEET) = 624.40
STREET LENGTH(FEET) = 290.00 CURB HEIGHT(INCHES) = 6.0
STREET HALFWIDTH(FEET) = 26.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 18.00
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) = 0.0150
Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150
**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 0.85
STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:
STREET FLOW DEPTH(FEET) = 0.24
HALFSTREET FLOOD WIDTH(FEET) = 5.89
AVERAGE FLOW VELOCITY(FEET/SEC.) = 1.82
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 0.44
STREET FLOW TRAVEL TIME(MIN.) = 2.65 Tc(MIN.) = 8.10
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.207
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .7900
AREA-AVERAGE RUNOFF COEFFICIENT = 0.759
SUBAREA AREA(ACRES) = 0.29 SUBAREA RUNOFF(CFS) = 0.96
TOTAL AREA(ACRES) = 0.4 PEAK FLOW RATE(CFS) = 1.25
END OF SUBAREA STREET FLOW HYDRAULICS:
DEPTH(FEET) = 0.27 HALFSTREET FLOOD WIDTH(FEET) = 7.16
FLOW VELOCITY(FEET/SEC.) = 1.97 DEPTH*VELOCITY(FT*FT/SEC.) = 0.53
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 3.00 = 350.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 3.00 TO NODE 4.00 IS CODE = 31
----------------------------------------------------------------------------
>>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<<
============================================================================
ELEVATION DATA: UPSTREAM(FEET) = 619.00 DOWNSTREAM(FEET) = 607.83
FLOW LENGTH(FEET) = 320.00 MANNING'S N = 0.013
ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 18.000
DEPTH OF FLOW IN 18.0 INCH PIPE IS 3.2 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 5.97
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1
PIPE-FLOW(CFS) = 1.25
PIPE TRAVEL TIME(MIN.) = 0.89 Tc(MIN.) = 8.99
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 4.00 = 670.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 5.00 TO NODE 4.00 IS CODE = 81
----------------------------------------------------------------------------
>>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.933
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .9000
AREA-AVERAGE RUNOFF COEFFICIENT = 0.8155
SUBAREA AREA(ACRES) = 0.26 SUBAREA RUNOFF(CFS) = 0.92
TOTAL AREA(ACRES) = 0.6 TOTAL RUNOFF(CFS) = 2.08
TC(MIN.) = 8.99
****************************************************************************
FLOW PROCESS FROM NODE 4.00 TO NODE 9.00 IS CODE = 31
----------------------------------------------------------------------------
>>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
Page 2
50EX.OUT
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<<
============================================================================
ELEVATION DATA: UPSTREAM(FEET) = 607.83 DOWNSTREAM(FEET) = 603.22
FLOW LENGTH(FEET) = 310.00 MANNING'S N = 0.013
ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 18.000
DEPTH OF FLOW IN 18.0 INCH PIPE IS 5.0 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 5.14
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1
PIPE-FLOW(CFS) = 2.08
PIPE TRAVEL TIME(MIN.) = 1.00 Tc(MIN.) = 10.00
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 9.00 = 980.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 9.00 TO NODE 9.00 IS CODE = 1
----------------------------------------------------------------------------
>>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<<
============================================================================
TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE:
TIME OF CONCENTRATION(MIN.) = 10.00
RAINFALL INTENSITY(INCH/HR) = 3.67
TOTAL STREAM AREA(ACRES) = 0.65
PEAK FLOW RATE(CFS) AT CONFLUENCE = 2.08
****************************************************************************
FLOW PROCESS FROM NODE 6.00 TO NODE 7.00 IS CODE = 21
----------------------------------------------------------------------------
>>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .7100
INITIAL SUBAREA FLOW-LENGTH(FEET) = 60.00
UPSTREAM ELEVATION(FEET) = 625.50
DOWNSTREAM ELEVATION(FEET) = 625.00
ELEVATION DIFFERENCE(FEET) = 0.50
URBAN SUBAREA OVERLAND TIME OF FLOW(MIN.) = 5.616
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN
THE MAXIMUM OVERLAND FLOW LENGTH = 56.67
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION!
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.329
SUBAREA RUNOFF(CFS) = 0.38
TOTAL AREA(ACRES) = 0.10 TOTAL RUNOFF(CFS) = 0.38
****************************************************************************
FLOW PROCESS FROM NODE 7.00 TO NODE 8.00 IS CODE = 62
----------------------------------------------------------------------------
>>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 6 USED)<<<<<
============================================================================
UPSTREAM ELEVATION(FEET) = 625.50 DOWNSTREAM ELEVATION(FEET) = 617.00
STREET LENGTH(FEET) = 490.00 CURB HEIGHT(INCHES) = 6.0
STREET HALFWIDTH(FEET) = 44.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 12.00
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) = 0.0150
Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150
**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 4.85
STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:
STREET FLOW DEPTH(FEET) = 0.36
HALFSTREET FLOOD WIDTH(FEET) = 11.78
AVERAGE FLOW VELOCITY(FEET/SEC.) = 3.22
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 1.17
STREET FLOW TRAVEL TIME(MIN.) = 2.53 Tc(MIN.) = 8.15
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.191
Page 3
50EX.OUT
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .8000
AREA-AVERAGE RUNOFF COEFFICIENT = 0.797
SUBAREA AREA(ACRES) = 2.65 SUBAREA RUNOFF(CFS) = 8.89
TOTAL AREA(ACRES) = 2.8 PEAK FLOW RATE(CFS) = 9.18
END OF SUBAREA STREET FLOW HYDRAULICS:
DEPTH(FEET) = 0.43 HALFSTREET FLOOD WIDTH(FEET) = 15.23
FLOW VELOCITY(FEET/SEC.) = 3.77 DEPTH*VELOCITY(FT*FT/SEC.) = 1.62
LONGEST FLOWPATH FROM NODE 6.00 TO NODE 8.00 = 550.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 8.00 TO NODE 9.00 IS CODE = 31
----------------------------------------------------------------------------
>>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<<
============================================================================
ELEVATION DATA: UPSTREAM(FEET) = 606.00 DOWNSTREAM(FEET) = 603.22
FLOW LENGTH(FEET) = 125.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 18.0 INCH PIPE IS 10.2 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 8.85
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1
PIPE-FLOW(CFS) = 9.18
PIPE TRAVEL TIME(MIN.) = 0.24 Tc(MIN.) = 8.38
LONGEST FLOWPATH FROM NODE 6.00 TO NODE 9.00 = 675.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 9.00 TO NODE 9.00 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.) = 8.38
RAINFALL INTENSITY(INCH/HR) = 4.12
TOTAL STREAM AREA(ACRES) = 2.75
PEAK FLOW RATE(CFS) AT CONFLUENCE = 9.18
** CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 2.08 10.00 3.673 0.65
2 9.18 8.38 4.115 2.75
RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO
CONFLUENCE FORMULA USED FOR 2 STREAMS.
** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 10.93 8.38 4.115
2 10.28 10.00 3.673
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:
PEAK FLOW RATE(CFS) = 10.93 Tc(MIN.) = 8.38
TOTAL AREA(ACRES) = 3.4
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 9.00 = 980.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 10.00 TO NODE 11.00 IS CODE = 21
----------------------------------------------------------------------------
>>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .6500
INITIAL SUBAREA FLOW-LENGTH(FEET) = 60.00
UPSTREAM ELEVATION(FEET) = 627.50
DOWNSTREAM ELEVATION(FEET) = 627.00
ELEVATION DIFFERENCE(FEET) = 0.50
URBAN SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.479
Page 4
50EX.OUT
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN
THE MAXIMUM OVERLAND FLOW LENGTH = 56.67
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION!
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.859
SUBAREA RUNOFF(CFS) = 0.32
TOTAL AREA(ACRES) = 0.10 TOTAL RUNOFF(CFS) = 0.32
****************************************************************************
FLOW PROCESS FROM NODE 11.00 TO NODE 12.00 IS CODE = 62
----------------------------------------------------------------------------
>>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 6 USED)<<<<<
============================================================================
UPSTREAM ELEVATION(FEET) = 627.00 DOWNSTREAM ELEVATION(FEET) = 617.60
STREET LENGTH(FEET) = 480.00 CURB HEIGHT(INCHES) = 6.0
STREET HALFWIDTH(FEET) = 44.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 12.00
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) = 0.0150
Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150
**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 4.92
STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:
STREET FLOW DEPTH(FEET) = 0.36
HALFSTREET FLOOD WIDTH(FEET) = 11.54
AVERAGE FLOW VELOCITY(FEET/SEC.) = 3.40
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 1.21
STREET FLOW TRAVEL TIME(MIN.) = 2.35 Tc(MIN.) = 8.83
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.979
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .8200
AREA-AVERAGE RUNOFF COEFFICIENT = 0.814
SUBAREA AREA(ACRES) = 2.83 SUBAREA RUNOFF(CFS) = 9.23
TOTAL AREA(ACRES) = 2.9 PEAK FLOW RATE(CFS) = 9.49
END OF SUBAREA STREET FLOW HYDRAULICS:
DEPTH(FEET) = 0.43 HALFSTREET FLOOD WIDTH(FEET) = 15.05
FLOW VELOCITY(FEET/SEC.) = 3.98 DEPTH*VELOCITY(FT*FT/SEC.) = 1.70
LONGEST FLOWPATH FROM NODE 10.00 TO NODE 12.00 = 540.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 13.00 TO NODE 14.00 IS CODE = 21
----------------------------------------------------------------------------
>>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .9000
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 623.60
DOWNSTREAM ELEVATION(FEET) = 622.00
ELEVATION DIFFERENCE(FEET) = 1.60
URBAN SUBAREA OVERLAND TIME OF FLOW(MIN.) = 2.501
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN
THE MAXIMUM OVERLAND FLOW LENGTH = 66.00
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION!
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.744
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.
SUBAREA RUNOFF(CFS) = 0.47
TOTAL AREA(ACRES) = 0.09 TOTAL RUNOFF(CFS) = 0.47
****************************************************************************
FLOW PROCESS FROM NODE 14.00 TO NODE 17.00 IS CODE = 62
----------------------------------------------------------------------------
>>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
Page 5
50EX.OUT
>>>>>(STREET TABLE SECTION # 7 USED)<<<<<
============================================================================
UPSTREAM ELEVATION(FEET) = 622.00 DOWNSTREAM ELEVATION(FEET) = 615.10
STREET LENGTH(FEET) = 1000.00 CURB HEIGHT(INCHES) = 6.0
STREET HALFWIDTH(FEET) = 12.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 7.00
INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 2
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 = 0.0150
**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 10.63
***STREET FLOWING FULL***
STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:
STREET FLOW DEPTH(FEET) = 0.41
HALFSTREET FLOOD WIDTH(FEET) = 12.00
AVERAGE FLOW VELOCITY(FEET/SEC.) = 2.52
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 1.04
STREET FLOW TRAVEL TIME(MIN.) = 6.61 Tc(MIN.) = 9.11
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.900
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .8300
AREA-AVERAGE RUNOFF COEFFICIENT = 0.831
SUBAREA AREA(ACRES) = 5.86 SUBAREA RUNOFF(CFS) = 18.97
TOTAL AREA(ACRES) = 6.0 PEAK FLOW RATE(CFS) = 19.29
END OF SUBAREA STREET FLOW HYDRAULICS:
DEPTH(FEET) = 0.49 HALFSTREET FLOOD WIDTH(FEET) = 12.00
FLOW VELOCITY(FEET/SEC.) = 3.18 DEPTH*VELOCITY(FT*FT/SEC.) = 1.56
*NOTE: INITIAL SUBAREA NOMOGRAPH WITH SUBAREA PARAMETERS,
AND L = 1000.0 FT WITH ELEVATION-DROP = 6.9 FT, IS 27.9 CFS,
WHICH EXCEEDS THE TOP-OF-CURB STREET CAPACITY AT NODE 17.00
LONGEST FLOWPATH FROM NODE 13.00 TO NODE 17.00 = 1100.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 15.00 TO NODE 17.00 IS CODE = 81
----------------------------------------------------------------------------
>>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.900
*USER SPECIFIED(SUBAREA):
PARKS, GOLF COURSES RUNOFF COEFFICIENT = .3000
AREA-AVERAGE RUNOFF COEFFICIENT = 0.6295
SUBAREA AREA(ACRES) = 3.64 SUBAREA RUNOFF(CFS) = 4.26
TOTAL AREA(ACRES) = 9.6 TOTAL RUNOFF(CFS) = 23.55
TC(MIN.) = 9.11
****************************************************************************
FLOW PROCESS FROM NODE 16.00 TO NODE 17.00 IS CODE = 81
----------------------------------------------------------------------------
>>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.900
*USER SPECIFIED(SUBAREA):
BARREN SLOPES (FLAT) RUNOFF COEFFICIENT = .6500
AREA-AVERAGE RUNOFF COEFFICIENT = 0.6322
SUBAREA AREA(ACRES) = 1.43 SUBAREA RUNOFF(CFS) = 3.63
TOTAL AREA(ACRES) = 11.0 TOTAL RUNOFF(CFS) = 27.17
TC(MIN.) = 9.11
============================================================================
END OF STUDY SUMMARY:
TOTAL AREA(ACRES) = 11.0 TC(MIN.) = 9.11
PEAK FLOW RATE(CFS) = 27.17
============================================================================
============================================================================
END OF RATIONAL METHOD ANALYSIS
Page 6
Otay Ranch Town Center
Drainage Study
CHAPTER 3
HYDROLOGIC ANALYSIS
3.2 – 50-Year Developed Condition
AES Model Output
50PR.OUT
____________________________________________________________________________
****************************************************************************
RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE
Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT
2003,1985,1981 HYDROLOGY MANUAL
(c) Copyright 1982-2015 Advanced Engineering Software (aes)
Ver. 22.0 Release Date: 07/01/2015 License ID 1239
Analysis prepared by:
Hunsaker & Associates San Diego, Inc.
9707 Waples Street
San Diego, CA 92121
************************** DESCRIPTION OF STUDY **************************
* Otay Ranch town Center *
* 50-year return interval *
* DLN: 1643, w.O 3553-0002 *
**************************************************************************
FILE NAME: R:\1643\HYD\TM\DR\CALCS\AES\50\50PR.DAT
TIME/DATE OF STUDY: 14:15 02/08/2023
----------------------------------------------------------------------------
USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION:
----------------------------------------------------------------------------
2003 SAN DIEGO MANUAL CRITERIA
USER SPECIFIED STORM EVENT(YEAR) = 50.00
6-HOUR DURATION PRECIPITATION (INCHES) = 2.180
SPECIFIED MINIMUM PIPE SIZE(INCH) = 18.00
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 0.0313 0.167 0.0150
2 17.0 10.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.125 0.0150
3 20.0 12.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.125 0.0150
4 16.0 10.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.125 0.0150
5 26.0 18.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.125 0.0150
6 44.0 12.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.125 0.0150
7 12.0 5.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.125 0.0150
8 20.0 10.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.125 0.0150
GLOBAL STREET FLOW-DEPTH CONSTRAINTS:
1. Relative Flow-Depth = 0.50 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.*
+--------------------------------------------------------------------------+
| AREA ROUTING TO THE DETENTION VAULT |
| |
| |
+--------------------------------------------------------------------------+
****************************************************************************
FLOW PROCESS FROM NODE 1.00 TO NODE 2.00 IS CODE = 21
----------------------------------------------------------------------------
>>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .6900
INITIAL SUBAREA FLOW-LENGTH(FEET) = 85.00
UPSTREAM ELEVATION(FEET) = 628.30
Page 1
50PR.OUT
DOWNSTREAM ELEVATION(FEET) = 627.60
ELEVATION DIFFERENCE(FEET) = 0.70
URBAN SUBAREA OVERLAND TIME OF FLOW(MIN.) = 5.917
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN
THE MAXIMUM OVERLAND FLOW LENGTH = 56.47
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION!
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.153
SUBAREA RUNOFF(CFS) = 0.36
TOTAL AREA(ACRES) = 0.10 TOTAL RUNOFF(CFS) = 0.36
****************************************************************************
FLOW PROCESS FROM NODE 2.00 TO NODE 3.00 IS CODE = 62
----------------------------------------------------------------------------
>>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 4 USED)<<<<<
============================================================================
UPSTREAM ELEVATION(FEET) = 627.50 DOWNSTREAM ELEVATION(FEET) = 616.30
STREET LENGTH(FEET) = 740.00 CURB HEIGHT(INCHES) = 6.0
STREET HALFWIDTH(FEET) = 16.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 10.00
INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 2
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 = 0.0150
**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 2.64
STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:
STREET FLOW DEPTH(FEET) = 0.26
HALFSTREET FLOOD WIDTH(FEET) = 6.74
AVERAGE FLOW VELOCITY(FEET/SEC.) = 2.31
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 0.60
STREET FLOW TRAVEL TIME(MIN.) = 5.35 Tc(MIN.) = 11.27
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.401
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .6300
AREA-AVERAGE RUNOFF COEFFICIENT = 0.633
SUBAREA AREA(ACRES) = 2.08 SUBAREA RUNOFF(CFS) = 4.46
TOTAL AREA(ACRES) = 2.2 PEAK FLOW RATE(CFS) = 4.69
END OF SUBAREA STREET FLOW HYDRAULICS:
DEPTH(FEET) = 0.30 HALFSTREET FLOOD WIDTH(FEET) = 8.85
FLOW VELOCITY(FEET/SEC.) = 2.60 DEPTH*VELOCITY(FT*FT/SEC.) = 0.79
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 3.00 = 825.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 3.00 TO NODE 7.30 IS CODE = 31
----------------------------------------------------------------------------
>>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<<
============================================================================
ELEVATION DATA: UPSTREAM(FEET) = 611.80 DOWNSTREAM(FEET) = 609.50
FLOW LENGTH(FEET) = 350.00 MANNING'S N = 0.013
ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 18.000
DEPTH OF FLOW IN 18.0 INCH PIPE IS 9.8 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 4.74
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1
PIPE-FLOW(CFS) = 4.69
PIPE TRAVEL TIME(MIN.) = 1.23 Tc(MIN.) = 12.50
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 7.30 = 1175.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 7.00 TO NODE 7.30 IS CODE = 81
----------------------------------------------------------------------------
>>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.181
Page 2
50PR.OUT
*USER SPECIFIED(SUBAREA):
DENSE RESIDENTIAL (R2,R3) RUNOFF COEFFICIENT = .8800
AREA-AVERAGE RUNOFF COEFFICIENT = 0.6743
SUBAREA AREA(ACRES) = 0.44 SUBAREA RUNOFF(CFS) = 1.23
TOTAL AREA(ACRES) = 2.6 TOTAL RUNOFF(CFS) = 5.62
TC(MIN.) = 12.50
****************************************************************************
FLOW PROCESS FROM NODE 7.30 TO NODE 10.00 IS CODE = 31
----------------------------------------------------------------------------
>>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<<
============================================================================
ELEVATION DATA: UPSTREAM(FEET) = 609.50 DOWNSTREAM(FEET) = 608.00
FLOW LENGTH(FEET) = 250.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 18.0 INCH PIPE IS 11.4 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 4.77
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1
PIPE-FLOW(CFS) = 5.62
PIPE TRAVEL TIME(MIN.) = 0.87 Tc(MIN.) = 13.37
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 10.00 = 1425.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 11.00 TO NODE 10.00 IS CODE = 81
----------------------------------------------------------------------------
>>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.046
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .7500
AREA-AVERAGE RUNOFF COEFFICIENT = 0.7173
SUBAREA AREA(ACRES) = 3.45 SUBAREA RUNOFF(CFS) = 7.88
TOTAL AREA(ACRES) = 6.1 TOTAL RUNOFF(CFS) = 13.26
TC(MIN.) = 13.37
****************************************************************************
FLOW PROCESS FROM NODE 10.00 TO NODE 12.00 IS CODE = 31
----------------------------------------------------------------------------
>>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<<
============================================================================
ELEVATION DATA: UPSTREAM(FEET) = 608.00 DOWNSTREAM(FEET) = 607.60
FLOW LENGTH(FEET) = 50.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 21.0 INCH PIPE IS 17.0 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 6.37
ESTIMATED PIPE DIAMETER(INCH) = 21.00 NUMBER OF PIPES = 1
PIPE-FLOW(CFS) = 13.26
PIPE TRAVEL TIME(MIN.) = 0.13 Tc(MIN.) = 13.50
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 12.00 = 1475.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 12.00 TO NODE 12.00 IS CODE = 1
----------------------------------------------------------------------------
>>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<<
============================================================================
TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE:
TIME OF CONCENTRATION(MIN.) = 13.50
RAINFALL INTENSITY(INCH/HR) = 3.03
TOTAL STREAM AREA(ACRES) = 6.07
PEAK FLOW RATE(CFS) AT CONFLUENCE = 13.26
****************************************************************************
FLOW PROCESS FROM NODE 8.00 TO NODE 9.00 IS CODE = 21
----------------------------------------------------------------------------
>>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .7500
INITIAL SUBAREA FLOW-LENGTH(FEET) = 60.00
UPSTREAM ELEVATION(FEET) = 618.60
Page 3
50PR.OUT
DOWNSTREAM ELEVATION(FEET) = 617.90
ELEVATION DIFFERENCE(FEET) = 0.70
URBAN SUBAREA OVERLAND TIME OF FLOW(MIN.) = 4.636
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.744
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.
SUBAREA RUNOFF(CFS) = 0.26
TOTAL AREA(ACRES) = 0.06 TOTAL RUNOFF(CFS) = 0.26
****************************************************************************
FLOW PROCESS FROM NODE 9.00 TO NODE 12.00 IS CODE = 62
----------------------------------------------------------------------------
>>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 7 USED)<<<<<
============================================================================
UPSTREAM ELEVATION(FEET) = 617.90 DOWNSTREAM ELEVATION(FEET) = 615.90
STREET LENGTH(FEET) = 370.00 CURB HEIGHT(INCHES) = 6.0
STREET HALFWIDTH(FEET) = 12.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 5.00
INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 2
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 = 0.0150
**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 1.51
STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:
STREET FLOW DEPTH(FEET) = 0.26
HALFSTREET FLOOD WIDTH(FEET) = 6.61
AVERAGE FLOW VELOCITY(FEET/SEC.) = 1.36
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 0.35
STREET FLOW TRAVEL TIME(MIN.) = 4.54 Tc(MIN.) = 9.18
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.882
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .7800
AREA-AVERAGE RUNOFF COEFFICIENT = 0.778
SUBAREA AREA(ACRES) = 0.81 SUBAREA RUNOFF(CFS) = 2.45
TOTAL AREA(ACRES) = 0.9 PEAK FLOW RATE(CFS) = 2.63
END OF SUBAREA STREET FLOW HYDRAULICS:
DEPTH(FEET) = 0.30 HALFSTREET FLOOD WIDTH(FEET) = 8.60
FLOW VELOCITY(FEET/SEC.) = 1.53 DEPTH*VELOCITY(FT*FT/SEC.) = 0.46
LONGEST FLOWPATH FROM NODE 8.00 TO NODE 12.00 = 430.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 12.00 TO NODE 12.00 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.) = 9.18
RAINFALL INTENSITY(INCH/HR) = 3.88
TOTAL STREAM AREA(ACRES) = 0.87
PEAK FLOW RATE(CFS) AT CONFLUENCE = 2.63
** CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 13.26 13.50 3.027 6.07
2 2.63 9.18 3.882 0.87
RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO
CONFLUENCE FORMULA USED FOR 2 STREAMS.
** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
Page 4
50PR.OUT
1 11.64 9.18 3.882
2 15.31 13.50 3.027
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:
PEAK FLOW RATE(CFS) = 15.31 Tc(MIN.) = 13.50
TOTAL AREA(ACRES) = 6.9
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 12.00 = 1475.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 12.00 TO NODE 14.00 IS CODE = 31
----------------------------------------------------------------------------
>>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<<
============================================================================
ELEVATION DATA: UPSTREAM(FEET) = 607.60 DOWNSTREAM(FEET) = 606.35
FLOW LENGTH(FEET) = 250.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 27.0 INCH PIPE IS 17.2 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 5.72
ESTIMATED PIPE DIAMETER(INCH) = 27.00 NUMBER OF PIPES = 1
PIPE-FLOW(CFS) = 15.31
PIPE TRAVEL TIME(MIN.) = 0.73 Tc(MIN.) = 14.23
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 14.00 = 1725.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 13.00 TO NODE 14.00 IS CODE = 81
----------------------------------------------------------------------------
>>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.926
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .7500
AREA-AVERAGE RUNOFF COEFFICIENT = 0.7319
SUBAREA AREA(ACRES) = 2.66 SUBAREA RUNOFF(CFS) = 5.84
TOTAL AREA(ACRES) = 9.6 TOTAL RUNOFF(CFS) = 20.56
TC(MIN.) = 14.23
****************************************************************************
FLOW PROCESS FROM NODE 14.00 TO NODE 15.00 IS CODE = 31
----------------------------------------------------------------------------
>>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<<
============================================================================
ELEVATION DATA: UPSTREAM(FEET) = 606.35 DOWNSTREAM(FEET) = 605.50
FLOW LENGTH(FEET) = 75.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 24.0 INCH PIPE IS 17.8 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 8.23
ESTIMATED PIPE DIAMETER(INCH) = 24.00 NUMBER OF PIPES = 1
PIPE-FLOW(CFS) = 20.56
PIPE TRAVEL TIME(MIN.) = 0.15 Tc(MIN.) = 14.38
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 15.00 = 1800.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 15.00 TO NODE 15.00 IS CODE = 10
----------------------------------------------------------------------------
>>>>>MAIN-STREAM MEMORY COPIED ONTO MEMORY BANK # 1 <<<<<
============================================================================
****************************************************************************
FLOW PROCESS FROM NODE 17.00 TO NODE 18.00 IS CODE = 21
----------------------------------------------------------------------------
>>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .6300
INITIAL SUBAREA FLOW-LENGTH(FEET) = 60.00
UPSTREAM ELEVATION(FEET) = 616.00
DOWNSTREAM ELEVATION(FEET) = 615.50
ELEVATION DIFFERENCE(FEET) = 0.50
URBAN SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.767
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN
THE MAXIMUM OVERLAND FLOW LENGTH = 56.67
Page 5
50PR.OUT
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION!
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.725
SUBAREA RUNOFF(CFS) = 0.30
TOTAL AREA(ACRES) = 0.10 TOTAL RUNOFF(CFS) = 0.30
****************************************************************************
FLOW PROCESS FROM NODE 18.00 TO NODE 19.00 IS CODE = 62
----------------------------------------------------------------------------
>>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 7 USED)<<<<<
============================================================================
UPSTREAM ELEVATION(FEET) = 615.50 DOWNSTREAM ELEVATION(FEET) = 614.30
STREET LENGTH(FEET) = 150.00 CURB HEIGHT(INCHES) = 6.0
STREET HALFWIDTH(FEET) = 12.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 5.00
INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 2
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 = 0.0150
**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 2.71
STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:
STREET FLOW DEPTH(FEET) = 0.29
HALFSTREET FLOOD WIDTH(FEET) = 7.98
AVERAGE FLOW VELOCITY(FEET/SEC.) = 1.79
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 0.51
STREET FLOW TRAVEL TIME(MIN.) = 1.39 Tc(MIN.) = 8.16
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.187
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .7900
AREA-AVERAGE RUNOFF COEFFICIENT = 0.780
SUBAREA AREA(ACRES) = 1.46 SUBAREA RUNOFF(CFS) = 4.83
TOTAL AREA(ACRES) = 1.6 PEAK FLOW RATE(CFS) = 5.09
END OF SUBAREA STREET FLOW HYDRAULICS:
DEPTH(FEET) = 0.34 HALFSTREET FLOOD WIDTH(FEET) = 10.55
FLOW VELOCITY(FEET/SEC.) = 2.07 DEPTH*VELOCITY(FT*FT/SEC.) = 0.70
LONGEST FLOWPATH FROM NODE 17.00 TO NODE 19.00 = 210.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 16.00 TO NODE 19.00 IS CODE = 81
----------------------------------------------------------------------------
>>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.187
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .7500
AREA-AVERAGE RUNOFF COEFFICIENT = 0.7589
SUBAREA AREA(ACRES) = 3.66 SUBAREA RUNOFF(CFS) = 11.49
TOTAL AREA(ACRES) = 5.2 TOTAL RUNOFF(CFS) = 16.59
TC(MIN.) = 8.16
****************************************************************************
FLOW PROCESS FROM NODE 19.00 TO NODE 15.00 IS CODE = 31
----------------------------------------------------------------------------
>>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<<
============================================================================
ELEVATION DATA: UPSTREAM(FEET) = 605.90 DOWNSTREAM(FEET) = 605.50
FLOW LENGTH(FEET) = 40.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 24.0 INCH PIPE IS 15.8 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 7.54
ESTIMATED PIPE DIAMETER(INCH) = 24.00 NUMBER OF PIPES = 1
PIPE-FLOW(CFS) = 16.59
PIPE TRAVEL TIME(MIN.) = 0.09 Tc(MIN.) = 8.25
LONGEST FLOWPATH FROM NODE 17.00 TO NODE 15.00 = 250.00 FEET.
Page 6
50PR.OUT
****************************************************************************
FLOW PROCESS FROM NODE 15.00 TO NODE 15.00 IS CODE = 11
----------------------------------------------------------------------------
>>>>>CONFLUENCE MEMORY BANK # 1 WITH THE MAIN-STREAM MEMORY<<<<<
============================================================================
** MAIN STREAM CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 16.59 8.25 4.158 5.22
LONGEST FLOWPATH FROM NODE 17.00 TO NODE 15.00 = 250.00 FEET.
** MEMORY BANK # 1 CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 20.56 14.38 2.906 9.60
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 15.00 = 1800.00 FEET.
** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 28.38 8.25 4.158
2 32.15 14.38 2.906
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:
PEAK FLOW RATE(CFS) = 32.15 Tc(MIN.) = 14.38
TOTAL AREA(ACRES) = 14.8
****************************************************************************
FLOW PROCESS FROM NODE 15.00 TO NODE 15.00 IS CODE = 12
----------------------------------------------------------------------------
>>>>>CLEAR MEMORY BANK # 1 <<<<<
============================================================================
****************************************************************************
FLOW PROCESS FROM NODE 15.00 TO NODE 20.00 IS CODE = 31
----------------------------------------------------------------------------
>>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<<
============================================================================
ELEVATION DATA: UPSTREAM(FEET) = 601.50 DOWNSTREAM(FEET) = 599.80
FLOW LENGTH(FEET) = 140.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 27.0 INCH PIPE IS 22.0 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 9.28
ESTIMATED PIPE DIAMETER(INCH) = 27.00 NUMBER OF PIPES = 1
PIPE-FLOW(CFS) = 32.15
PIPE TRAVEL TIME(MIN.) = 0.25 Tc(MIN.) = 14.63
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 20.00 = 1940.00 FEET.
+--------------------------------------------------------------------------+
| AREA NOT ROUTING TO THE DETENTION VAULT |
| |
| |
+--------------------------------------------------------------------------+
****************************************************************************
FLOW PROCESS FROM NODE 4.00 TO NODE 5.00 IS CODE = 21
----------------------------------------------------------------------------
>>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .7600
INITIAL SUBAREA FLOW-LENGTH(FEET) = 60.00
UPSTREAM ELEVATION(FEET) = 618.60
DOWNSTREAM ELEVATION(FEET) = 618.00
ELEVATION DIFFERENCE(FEET) = 0.60
URBAN SUBAREA OVERLAND TIME OF FLOW(MIN.) = 4.741
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN
THE MAXIMUM OVERLAND FLOW LENGTH = 60.00
(Reference: Table 3-1B of Hydrology Manual)
Page 7
50PR.OUT
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION!
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.744
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.
SUBAREA RUNOFF(CFS) = 0.17
TOTAL AREA(ACRES) = 0.04 TOTAL RUNOFF(CFS) = 0.17
****************************************************************************
FLOW PROCESS FROM NODE 5.00 TO NODE 6.00 IS CODE = 62
----------------------------------------------------------------------------
>>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 7 USED)<<<<<
============================================================================
UPSTREAM ELEVATION(FEET) = 618.00 DOWNSTREAM ELEVATION(FEET) = 616.50
STREET LENGTH(FEET) = 270.00 CURB HEIGHT(INCHES) = 6.0
STREET HALFWIDTH(FEET) = 12.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 5.00
INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 2
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 = 0.0150
**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 0.69
STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:
STREET FLOW DEPTH(FEET) = 0.21
HALFSTREET FLOOD WIDTH(FEET) = 4.12
AVERAGE FLOW VELOCITY(FEET/SEC.) = 1.20
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 0.25
STREET FLOW TRAVEL TIME(MIN.) = 3.76 Tc(MIN.) = 8.50
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.080
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .7800
AREA-AVERAGE RUNOFF COEFFICIENT = 0.778
SUBAREA AREA(ACRES) = 0.32 SUBAREA RUNOFF(CFS) = 1.02
TOTAL AREA(ACRES) = 0.4 PEAK FLOW RATE(CFS) = 1.14
END OF SUBAREA STREET FLOW HYDRAULICS:
DEPTH(FEET) = 0.24 HALFSTREET FLOOD WIDTH(FEET) = 5.67
FLOW VELOCITY(FEET/SEC.) = 1.30 DEPTH*VELOCITY(FT*FT/SEC.) = 0.31
LONGEST FLOWPATH FROM NODE 4.00 TO NODE 6.00 = 330.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 21.00 TO NODE 22.00 IS CODE = 21
----------------------------------------------------------------------------
>>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .6500
INITIAL SUBAREA FLOW-LENGTH(FEET) = 60.00
UPSTREAM ELEVATION(FEET) = 627.60
DOWNSTREAM ELEVATION(FEET) = 627.00
ELEVATION DIFFERENCE(FEET) = 0.60
URBAN SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.274
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN
THE MAXIMUM OVERLAND FLOW LENGTH = 60.00
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION!
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.961
SUBAREA RUNOFF(CFS) = 0.32
TOTAL AREA(ACRES) = 0.10 TOTAL RUNOFF(CFS) = 0.32
****************************************************************************
FLOW PROCESS FROM NODE 22.00 TO NODE 23.00 IS CODE = 62
----------------------------------------------------------------------------
>>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 6 USED)<<<<<
============================================================================
UPSTREAM ELEVATION(FEET) = 627.00 DOWNSTREAM ELEVATION(FEET) = 617.60
Page 8
50PR.OUT
STREET LENGTH(FEET) = 560.00 CURB HEIGHT(INCHES) = 6.0
STREET HALFWIDTH(FEET) = 44.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 12.00
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) = 0.0150
Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150
**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 3.70
STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:
STREET FLOW DEPTH(FEET) = 0.34
HALFSTREET FLOOD WIDTH(FEET) = 10.58
AVERAGE FLOW VELOCITY(FEET/SEC.) = 2.98
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 1.01
STREET FLOW TRAVEL TIME(MIN.) = 3.13 Tc(MIN.) = 9.40
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.822
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .8400
AREA-AVERAGE RUNOFF COEFFICIENT = 0.831
SUBAREA AREA(ACRES) = 2.10 SUBAREA RUNOFF(CFS) = 6.74
TOTAL AREA(ACRES) = 2.2 PEAK FLOW RATE(CFS) = 6.99
END OF SUBAREA STREET FLOW HYDRAULICS:
DEPTH(FEET) = 0.40 HALFSTREET FLOOD WIDTH(FEET) = 13.74
FLOW VELOCITY(FEET/SEC.) = 3.48 DEPTH*VELOCITY(FT*FT/SEC.) = 1.40
LONGEST FLOWPATH FROM NODE 21.00 TO NODE 23.00 = 620.00 FEET.
============================================================================
END OF STUDY SUMMARY:
TOTAL AREA(ACRES) = 2.2 TC(MIN.) = 9.40
PEAK FLOW RATE(CFS) = 6.99
============================================================================
============================================================================
END OF RATIONAL METHOD ANALYSIS
Page 9
Otay Ranch Town Center
Drainage Study
CHAPTER 3
HYDROLOGIC ANALYSIS
3.3 – 100-Year Existing Condition
AES Model Output
100EX.OUT
____________________________________________________________________________
****************************************************************************
RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE
Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT
2003,1985,1981 HYDROLOGY MANUAL
(c) Copyright 1982-2015 Advanced Engineering Software (aes)
Ver. 22.0 Release Date: 07/01/2015 License ID 1239
Analysis prepared by:
Hunsaker & Associates San Diego, Inc.
9707 Waples Street
San Diego, CA 92121
************************** DESCRIPTION OF STUDY **************************
* Otay Ranch town Center *
* 100-Year return interval *
* DLN: 1643, w.O 3553-0002 *
**************************************************************************
FILE NAME: R:\1643\HYD\TM\DR\CALCS\AES\100\100EX.DAT
TIME/DATE OF STUDY: 08:32 07/27/2022
----------------------------------------------------------------------------
USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION:
----------------------------------------------------------------------------
2003 SAN DIEGO MANUAL CRITERIA
USER SPECIFIED STORM EVENT(YEAR) = 100.00
6-HOUR DURATION PRECIPITATION (INCHES) = 2.500
SPECIFIED MINIMUM PIPE SIZE(INCH) = 18.00
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 0.0313 0.167 0.0150
2 17.0 10.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.125 0.0150
3 20.0 12.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.125 0.0150
4 16.0 10.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.125 0.0150
5 26.0 18.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.125 0.0150
6 44.0 12.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.125 0.0150
7 12.0 7.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.125 0.0150
GLOBAL STREET FLOW-DEPTH CONSTRAINTS:
1. Relative Flow-Depth = 0.50 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 2.00 IS CODE = 21
----------------------------------------------------------------------------
>>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .6700
INITIAL SUBAREA FLOW-LENGTH(FEET) = 60.00
UPSTREAM ELEVATION(FEET) = 628.30
DOWNSTREAM ELEVATION(FEET) = 627.50
ELEVATION DIFFERENCE(FEET) = 0.80
URBAN SUBAREA OVERLAND TIME OF FLOW(MIN.) = 5.447
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.233
SUBAREA RUNOFF(CFS) = 0.42
TOTAL AREA(ACRES) = 0.10 TOTAL RUNOFF(CFS) = 0.42
Page 1
100EX.OUT
****************************************************************************
FLOW PROCESS FROM NODE 2.00 TO NODE 3.00 IS CODE = 62
----------------------------------------------------------------------------
>>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 5 USED)<<<<<
============================================================================
UPSTREAM ELEVATION(FEET) = 627.50 DOWNSTREAM ELEVATION(FEET) = 624.40
STREET LENGTH(FEET) = 290.00 CURB HEIGHT(INCHES) = 6.0
STREET HALFWIDTH(FEET) = 26.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 18.00
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) = 0.0150
Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150
**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 0.97
STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:
STREET FLOW DEPTH(FEET) = 0.25
HALFSTREET FLOOD WIDTH(FEET) = 6.35
AVERAGE FLOW VELOCITY(FEET/SEC.) = 1.87
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 0.47
STREET FLOW TRAVEL TIME(MIN.) = 2.59 Tc(MIN.) = 8.03
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.852
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .7900
AREA-AVERAGE RUNOFF COEFFICIENT = 0.759
SUBAREA AREA(ACRES) = 0.29 SUBAREA RUNOFF(CFS) = 1.11
TOTAL AREA(ACRES) = 0.4 PEAK FLOW RATE(CFS) = 1.44
END OF SUBAREA STREET FLOW HYDRAULICS:
DEPTH(FEET) = 0.28 HALFSTREET FLOOD WIDTH(FEET) = 7.67
FLOW VELOCITY(FEET/SEC.) = 2.03 DEPTH*VELOCITY(FT*FT/SEC.) = 0.57
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 3.00 = 350.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 3.00 TO NODE 4.00 IS CODE = 31
----------------------------------------------------------------------------
>>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<<
============================================================================
ELEVATION DATA: UPSTREAM(FEET) = 619.00 DOWNSTREAM(FEET) = 607.83
FLOW LENGTH(FEET) = 320.00 MANNING'S N = 0.013
ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 18.000
DEPTH OF FLOW IN 18.0 INCH PIPE IS 3.4 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 6.24
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1
PIPE-FLOW(CFS) = 1.44
PIPE TRAVEL TIME(MIN.) = 0.85 Tc(MIN.) = 8.89
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 4.00 = 670.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 5.00 TO NODE 4.00 IS CODE = 81
----------------------------------------------------------------------------
>>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.546
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .9000
AREA-AVERAGE RUNOFF COEFFICIENT = 0.8155
SUBAREA AREA(ACRES) = 0.26 SUBAREA RUNOFF(CFS) = 1.06
TOTAL AREA(ACRES) = 0.6 TOTAL RUNOFF(CFS) = 2.41
TC(MIN.) = 8.89
****************************************************************************
FLOW PROCESS FROM NODE 4.00 TO NODE 9.00 IS CODE = 31
----------------------------------------------------------------------------
>>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
Page 2
100EX.OUT
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<<
============================================================================
ELEVATION DATA: UPSTREAM(FEET) = 607.83 DOWNSTREAM(FEET) = 603.22
FLOW LENGTH(FEET) = 310.00 MANNING'S N = 0.013
ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 18.000
DEPTH OF FLOW IN 18.0 INCH PIPE IS 5.4 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 5.36
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1
PIPE-FLOW(CFS) = 2.41
PIPE TRAVEL TIME(MIN.) = 0.96 Tc(MIN.) = 9.85
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 9.00 = 980.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 9.00 TO NODE 9.00 IS CODE = 1
----------------------------------------------------------------------------
>>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<<
============================================================================
TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE:
TIME OF CONCENTRATION(MIN.) = 9.85
RAINFALL INTENSITY(INCH/HR) = 4.25
TOTAL STREAM AREA(ACRES) = 0.65
PEAK FLOW RATE(CFS) AT CONFLUENCE = 2.41
****************************************************************************
FLOW PROCESS FROM NODE 6.00 TO NODE 7.00 IS CODE = 21
----------------------------------------------------------------------------
>>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .7100
INITIAL SUBAREA FLOW-LENGTH(FEET) = 60.00
UPSTREAM ELEVATION(FEET) = 625.50
DOWNSTREAM ELEVATION(FEET) = 625.00
ELEVATION DIFFERENCE(FEET) = 0.50
URBAN SUBAREA OVERLAND TIME OF FLOW(MIN.) = 5.616
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN
THE MAXIMUM OVERLAND FLOW LENGTH = 56.67
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION!
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.112
SUBAREA RUNOFF(CFS) = 0.43
TOTAL AREA(ACRES) = 0.10 TOTAL RUNOFF(CFS) = 0.43
****************************************************************************
FLOW PROCESS FROM NODE 7.00 TO NODE 8.00 IS CODE = 62
----------------------------------------------------------------------------
>>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 6 USED)<<<<<
============================================================================
UPSTREAM ELEVATION(FEET) = 625.50 DOWNSTREAM ELEVATION(FEET) = 617.00
STREET LENGTH(FEET) = 490.00 CURB HEIGHT(INCHES) = 6.0
STREET HALFWIDTH(FEET) = 44.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 12.00
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) = 0.0150
Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150
**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 5.59
STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:
STREET FLOW DEPTH(FEET) = 0.38
HALFSTREET FLOOD WIDTH(FEET) = 12.49
AVERAGE FLOW VELOCITY(FEET/SEC.) = 3.33
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 1.25
STREET FLOW TRAVEL TIME(MIN.) = 2.45 Tc(MIN.) = 8.07
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.839
Page 3
100EX.OUT
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .8000
AREA-AVERAGE RUNOFF COEFFICIENT = 0.797
SUBAREA AREA(ACRES) = 2.65 SUBAREA RUNOFF(CFS) = 10.26
TOTAL AREA(ACRES) = 2.8 PEAK FLOW RATE(CFS) = 10.60
END OF SUBAREA STREET FLOW HYDRAULICS:
DEPTH(FEET) = 0.45 HALFSTREET FLOOD WIDTH(FEET) = 16.12
FLOW VELOCITY(FEET/SEC.) = 3.90 DEPTH*VELOCITY(FT*FT/SEC.) = 1.75
LONGEST FLOWPATH FROM NODE 6.00 TO NODE 8.00 = 550.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 8.00 TO NODE 9.00 IS CODE = 31
----------------------------------------------------------------------------
>>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<<
============================================================================
ELEVATION DATA: UPSTREAM(FEET) = 606.00 DOWNSTREAM(FEET) = 603.22
FLOW LENGTH(FEET) = 125.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 18.0 INCH PIPE IS 11.2 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 9.14
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1
PIPE-FLOW(CFS) = 10.60
PIPE TRAVEL TIME(MIN.) = 0.23 Tc(MIN.) = 8.29
LONGEST FLOWPATH FROM NODE 6.00 TO NODE 9.00 = 675.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 9.00 TO NODE 9.00 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.) = 8.29
RAINFALL INTENSITY(INCH/HR) = 4.75
TOTAL STREAM AREA(ACRES) = 2.75
PEAK FLOW RATE(CFS) AT CONFLUENCE = 10.60
** CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 2.41 9.85 4.253 0.65
2 10.60 8.29 4.752 2.75
RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO
CONFLUENCE FORMULA USED FOR 2 STREAMS.
** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 12.63 8.29 4.752
2 11.90 9.85 4.253
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:
PEAK FLOW RATE(CFS) = 12.63 Tc(MIN.) = 8.29
TOTAL AREA(ACRES) = 3.4
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 9.00 = 980.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 10.00 TO NODE 11.00 IS CODE = 21
----------------------------------------------------------------------------
>>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .6500
INITIAL SUBAREA FLOW-LENGTH(FEET) = 60.00
UPSTREAM ELEVATION(FEET) = 627.50
DOWNSTREAM ELEVATION(FEET) = 627.00
ELEVATION DIFFERENCE(FEET) = 0.50
URBAN SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.479
Page 4
100EX.OUT
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN
THE MAXIMUM OVERLAND FLOW LENGTH = 56.67
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION!
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.573
SUBAREA RUNOFF(CFS) = 0.36
TOTAL AREA(ACRES) = 0.10 TOTAL RUNOFF(CFS) = 0.36
****************************************************************************
FLOW PROCESS FROM NODE 11.00 TO NODE 12.00 IS CODE = 62
----------------------------------------------------------------------------
>>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 6 USED)<<<<<
============================================================================
UPSTREAM ELEVATION(FEET) = 627.00 DOWNSTREAM ELEVATION(FEET) = 617.60
STREET LENGTH(FEET) = 480.00 CURB HEIGHT(INCHES) = 6.0
STREET HALFWIDTH(FEET) = 44.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 12.00
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) = 0.0150
Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150
**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 5.68
STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:
STREET FLOW DEPTH(FEET) = 0.37
HALFSTREET FLOOD WIDTH(FEET) = 12.25
AVERAGE FLOW VELOCITY(FEET/SEC.) = 3.51
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 1.30
STREET FLOW TRAVEL TIME(MIN.) = 2.28 Tc(MIN.) = 8.76
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.587
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .8200
AREA-AVERAGE RUNOFF COEFFICIENT = 0.814
SUBAREA AREA(ACRES) = 2.83 SUBAREA RUNOFF(CFS) = 10.65
TOTAL AREA(ACRES) = 2.9 PEAK FLOW RATE(CFS) = 10.94
END OF SUBAREA STREET FLOW HYDRAULICS:
DEPTH(FEET) = 0.45 HALFSTREET FLOOD WIDTH(FEET) = 15.95
FLOW VELOCITY(FEET/SEC.) = 4.11 DEPTH*VELOCITY(FT*FT/SEC.) = 1.83
LONGEST FLOWPATH FROM NODE 10.00 TO NODE 12.00 = 540.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 13.00 TO NODE 14.00 IS CODE = 21
----------------------------------------------------------------------------
>>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .9000
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 623.60
DOWNSTREAM ELEVATION(FEET) = 622.00
ELEVATION DIFFERENCE(FEET) = 1.60
URBAN SUBAREA OVERLAND TIME OF FLOW(MIN.) = 2.501
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN
THE MAXIMUM OVERLAND FLOW LENGTH = 66.00
(Reference: Table 3-1B 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) = 0.53
TOTAL AREA(ACRES) = 0.09 TOTAL RUNOFF(CFS) = 0.53
****************************************************************************
FLOW PROCESS FROM NODE 14.00 TO NODE 17.00 IS CODE = 62
----------------------------------------------------------------------------
>>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
Page 5
100EX.OUT
>>>>>(STREET TABLE SECTION # 7 USED)<<<<<
============================================================================
UPSTREAM ELEVATION(FEET) = 622.00 DOWNSTREAM ELEVATION(FEET) = 615.10
STREET LENGTH(FEET) = 1000.00 CURB HEIGHT(INCHES) = 6.0
STREET HALFWIDTH(FEET) = 12.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 7.00
INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 2
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 = 0.0150
**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 12.49
***STREET FLOWING FULL***
STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:
STREET FLOW DEPTH(FEET) = 0.43
HALFSTREET FLOOD WIDTH(FEET) = 12.00
AVERAGE FLOW VELOCITY(FEET/SEC.) = 2.68
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 1.15
STREET FLOW TRAVEL TIME(MIN.) = 6.21 Tc(MIN.) = 8.71
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.604
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .8300
AREA-AVERAGE RUNOFF COEFFICIENT = 0.831
SUBAREA AREA(ACRES) = 5.86 SUBAREA RUNOFF(CFS) = 22.39
TOTAL AREA(ACRES) = 6.0 PEAK FLOW RATE(CFS) = 22.77
END OF SUBAREA STREET FLOW HYDRAULICS:
DEPTH(FEET) = 0.51 HALFSTREET FLOOD WIDTH(FEET) = 12.73
FLOW VELOCITY(FEET/SEC.) = 3.40 DEPTH*VELOCITY(FT*FT/SEC.) = 1.75
*NOTE: INITIAL SUBAREA NOMOGRAPH WITH SUBAREA PARAMETERS,
AND L = 1000.0 FT WITH ELEVATION-DROP = 6.9 FT, IS 32.0 CFS,
WHICH EXCEEDS THE TOP-OF-CURB STREET CAPACITY AT NODE 17.00
LONGEST FLOWPATH FROM NODE 13.00 TO NODE 17.00 = 1100.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 15.00 TO NODE 17.00 IS CODE = 81
----------------------------------------------------------------------------
>>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.604
*USER SPECIFIED(SUBAREA):
PARKS, GOLF COURSES RUNOFF COEFFICIENT = .3000
AREA-AVERAGE RUNOFF COEFFICIENT = 0.6295
SUBAREA AREA(ACRES) = 3.64 SUBAREA RUNOFF(CFS) = 5.03
TOTAL AREA(ACRES) = 9.6 TOTAL RUNOFF(CFS) = 27.79
TC(MIN.) = 8.71
****************************************************************************
FLOW PROCESS FROM NODE 16.00 TO NODE 17.00 IS CODE = 81
----------------------------------------------------------------------------
>>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.604
*USER SPECIFIED(SUBAREA):
BARREN SLOPES (FLAT) RUNOFF COEFFICIENT = .6500
AREA-AVERAGE RUNOFF COEFFICIENT = 0.6322
SUBAREA AREA(ACRES) = 1.43 SUBAREA RUNOFF(CFS) = 4.28
TOTAL AREA(ACRES) = 11.0 TOTAL RUNOFF(CFS) = 32.07
TC(MIN.) = 8.71
============================================================================
END OF STUDY SUMMARY:
TOTAL AREA(ACRES) = 11.0 TC(MIN.) = 8.71
PEAK FLOW RATE(CFS) = 32.07
============================================================================
============================================================================
END OF RATIONAL METHOD ANALYSIS
Page 6
Otay Ranch Town Center
Drainage Study
CHAPTER 3
HYDROLOGIC ANALYSIS
3.4 – 100-Year Developed Condition
AES Model Output
50PR.OUT
____________________________________________________________________________
****************************************************************************
RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE
Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT
2003,1985,1981 HYDROLOGY MANUAL
(c) Copyright 1982-2015 Advanced Engineering Software (aes)
Ver. 22.0 Release Date: 07/01/2015 License ID 1239
Analysis prepared by:
Hunsaker & Associates San Diego, Inc.
9707 Waples Street
San Diego, CA 92121
************************** DESCRIPTION OF STUDY **************************
* Otay Ranch town Center *
* 50-year return interval *
* DLN: 1643, w.O 3553-0002 *
**************************************************************************
FILE NAME: R:\1643\HYD\TM\DR\CALCS\AES\50\50PR.DAT
TIME/DATE OF STUDY: 14:15 02/08/2023
----------------------------------------------------------------------------
USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION:
----------------------------------------------------------------------------
2003 SAN DIEGO MANUAL CRITERIA
USER SPECIFIED STORM EVENT(YEAR) = 50.00
6-HOUR DURATION PRECIPITATION (INCHES) = 2.180
SPECIFIED MINIMUM PIPE SIZE(INCH) = 18.00
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 0.0313 0.167 0.0150
2 17.0 10.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.125 0.0150
3 20.0 12.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.125 0.0150
4 16.0 10.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.125 0.0150
5 26.0 18.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.125 0.0150
6 44.0 12.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.125 0.0150
7 12.0 5.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.125 0.0150
8 20.0 10.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.125 0.0150
GLOBAL STREET FLOW-DEPTH CONSTRAINTS:
1. Relative Flow-Depth = 0.50 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.*
+--------------------------------------------------------------------------+
| AREA ROUTING TO THE DETENTION VAULT |
| |
| |
+--------------------------------------------------------------------------+
****************************************************************************
FLOW PROCESS FROM NODE 1.00 TO NODE 2.00 IS CODE = 21
----------------------------------------------------------------------------
>>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .6900
INITIAL SUBAREA FLOW-LENGTH(FEET) = 85.00
UPSTREAM ELEVATION(FEET) = 628.30
Page 1
50PR.OUT
DOWNSTREAM ELEVATION(FEET) = 627.60
ELEVATION DIFFERENCE(FEET) = 0.70
URBAN SUBAREA OVERLAND TIME OF FLOW(MIN.) = 5.917
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN
THE MAXIMUM OVERLAND FLOW LENGTH = 56.47
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION!
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.153
SUBAREA RUNOFF(CFS) = 0.36
TOTAL AREA(ACRES) = 0.10 TOTAL RUNOFF(CFS) = 0.36
****************************************************************************
FLOW PROCESS FROM NODE 2.00 TO NODE 3.00 IS CODE = 62
----------------------------------------------------------------------------
>>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 4 USED)<<<<<
============================================================================
UPSTREAM ELEVATION(FEET) = 627.50 DOWNSTREAM ELEVATION(FEET) = 616.30
STREET LENGTH(FEET) = 740.00 CURB HEIGHT(INCHES) = 6.0
STREET HALFWIDTH(FEET) = 16.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 10.00
INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 2
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 = 0.0150
**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 2.64
STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:
STREET FLOW DEPTH(FEET) = 0.26
HALFSTREET FLOOD WIDTH(FEET) = 6.74
AVERAGE FLOW VELOCITY(FEET/SEC.) = 2.31
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 0.60
STREET FLOW TRAVEL TIME(MIN.) = 5.35 Tc(MIN.) = 11.27
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.401
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .6300
AREA-AVERAGE RUNOFF COEFFICIENT = 0.633
SUBAREA AREA(ACRES) = 2.08 SUBAREA RUNOFF(CFS) = 4.46
TOTAL AREA(ACRES) = 2.2 PEAK FLOW RATE(CFS) = 4.69
END OF SUBAREA STREET FLOW HYDRAULICS:
DEPTH(FEET) = 0.30 HALFSTREET FLOOD WIDTH(FEET) = 8.85
FLOW VELOCITY(FEET/SEC.) = 2.60 DEPTH*VELOCITY(FT*FT/SEC.) = 0.79
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 3.00 = 825.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 3.00 TO NODE 7.30 IS CODE = 31
----------------------------------------------------------------------------
>>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<<
============================================================================
ELEVATION DATA: UPSTREAM(FEET) = 611.80 DOWNSTREAM(FEET) = 609.50
FLOW LENGTH(FEET) = 350.00 MANNING'S N = 0.013
ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 18.000
DEPTH OF FLOW IN 18.0 INCH PIPE IS 9.8 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 4.74
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1
PIPE-FLOW(CFS) = 4.69
PIPE TRAVEL TIME(MIN.) = 1.23 Tc(MIN.) = 12.50
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 7.30 = 1175.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 7.00 TO NODE 7.30 IS CODE = 81
----------------------------------------------------------------------------
>>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.181
Page 2
50PR.OUT
*USER SPECIFIED(SUBAREA):
DENSE RESIDENTIAL (R2,R3) RUNOFF COEFFICIENT = .8800
AREA-AVERAGE RUNOFF COEFFICIENT = 0.6743
SUBAREA AREA(ACRES) = 0.44 SUBAREA RUNOFF(CFS) = 1.23
TOTAL AREA(ACRES) = 2.6 TOTAL RUNOFF(CFS) = 5.62
TC(MIN.) = 12.50
****************************************************************************
FLOW PROCESS FROM NODE 7.30 TO NODE 10.00 IS CODE = 31
----------------------------------------------------------------------------
>>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<<
============================================================================
ELEVATION DATA: UPSTREAM(FEET) = 609.50 DOWNSTREAM(FEET) = 608.00
FLOW LENGTH(FEET) = 250.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 18.0 INCH PIPE IS 11.4 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 4.77
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1
PIPE-FLOW(CFS) = 5.62
PIPE TRAVEL TIME(MIN.) = 0.87 Tc(MIN.) = 13.37
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 10.00 = 1425.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 11.00 TO NODE 10.00 IS CODE = 81
----------------------------------------------------------------------------
>>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.046
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .7500
AREA-AVERAGE RUNOFF COEFFICIENT = 0.7173
SUBAREA AREA(ACRES) = 3.45 SUBAREA RUNOFF(CFS) = 7.88
TOTAL AREA(ACRES) = 6.1 TOTAL RUNOFF(CFS) = 13.26
TC(MIN.) = 13.37
****************************************************************************
FLOW PROCESS FROM NODE 10.00 TO NODE 12.00 IS CODE = 31
----------------------------------------------------------------------------
>>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<<
============================================================================
ELEVATION DATA: UPSTREAM(FEET) = 608.00 DOWNSTREAM(FEET) = 607.60
FLOW LENGTH(FEET) = 50.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 21.0 INCH PIPE IS 17.0 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 6.37
ESTIMATED PIPE DIAMETER(INCH) = 21.00 NUMBER OF PIPES = 1
PIPE-FLOW(CFS) = 13.26
PIPE TRAVEL TIME(MIN.) = 0.13 Tc(MIN.) = 13.50
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 12.00 = 1475.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 12.00 TO NODE 12.00 IS CODE = 1
----------------------------------------------------------------------------
>>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<<
============================================================================
TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE:
TIME OF CONCENTRATION(MIN.) = 13.50
RAINFALL INTENSITY(INCH/HR) = 3.03
TOTAL STREAM AREA(ACRES) = 6.07
PEAK FLOW RATE(CFS) AT CONFLUENCE = 13.26
****************************************************************************
FLOW PROCESS FROM NODE 8.00 TO NODE 9.00 IS CODE = 21
----------------------------------------------------------------------------
>>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .7500
INITIAL SUBAREA FLOW-LENGTH(FEET) = 60.00
UPSTREAM ELEVATION(FEET) = 618.60
Page 3
50PR.OUT
DOWNSTREAM ELEVATION(FEET) = 617.90
ELEVATION DIFFERENCE(FEET) = 0.70
URBAN SUBAREA OVERLAND TIME OF FLOW(MIN.) = 4.636
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.744
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.
SUBAREA RUNOFF(CFS) = 0.26
TOTAL AREA(ACRES) = 0.06 TOTAL RUNOFF(CFS) = 0.26
****************************************************************************
FLOW PROCESS FROM NODE 9.00 TO NODE 12.00 IS CODE = 62
----------------------------------------------------------------------------
>>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 7 USED)<<<<<
============================================================================
UPSTREAM ELEVATION(FEET) = 617.90 DOWNSTREAM ELEVATION(FEET) = 615.90
STREET LENGTH(FEET) = 370.00 CURB HEIGHT(INCHES) = 6.0
STREET HALFWIDTH(FEET) = 12.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 5.00
INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 2
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 = 0.0150
**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 1.51
STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:
STREET FLOW DEPTH(FEET) = 0.26
HALFSTREET FLOOD WIDTH(FEET) = 6.61
AVERAGE FLOW VELOCITY(FEET/SEC.) = 1.36
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 0.35
STREET FLOW TRAVEL TIME(MIN.) = 4.54 Tc(MIN.) = 9.18
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.882
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .7800
AREA-AVERAGE RUNOFF COEFFICIENT = 0.778
SUBAREA AREA(ACRES) = 0.81 SUBAREA RUNOFF(CFS) = 2.45
TOTAL AREA(ACRES) = 0.9 PEAK FLOW RATE(CFS) = 2.63
END OF SUBAREA STREET FLOW HYDRAULICS:
DEPTH(FEET) = 0.30 HALFSTREET FLOOD WIDTH(FEET) = 8.60
FLOW VELOCITY(FEET/SEC.) = 1.53 DEPTH*VELOCITY(FT*FT/SEC.) = 0.46
LONGEST FLOWPATH FROM NODE 8.00 TO NODE 12.00 = 430.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 12.00 TO NODE 12.00 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.) = 9.18
RAINFALL INTENSITY(INCH/HR) = 3.88
TOTAL STREAM AREA(ACRES) = 0.87
PEAK FLOW RATE(CFS) AT CONFLUENCE = 2.63
** CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 13.26 13.50 3.027 6.07
2 2.63 9.18 3.882 0.87
RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO
CONFLUENCE FORMULA USED FOR 2 STREAMS.
** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
Page 4
50PR.OUT
1 11.64 9.18 3.882
2 15.31 13.50 3.027
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:
PEAK FLOW RATE(CFS) = 15.31 Tc(MIN.) = 13.50
TOTAL AREA(ACRES) = 6.9
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 12.00 = 1475.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 12.00 TO NODE 14.00 IS CODE = 31
----------------------------------------------------------------------------
>>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<<
============================================================================
ELEVATION DATA: UPSTREAM(FEET) = 607.60 DOWNSTREAM(FEET) = 606.35
FLOW LENGTH(FEET) = 250.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 27.0 INCH PIPE IS 17.2 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 5.72
ESTIMATED PIPE DIAMETER(INCH) = 27.00 NUMBER OF PIPES = 1
PIPE-FLOW(CFS) = 15.31
PIPE TRAVEL TIME(MIN.) = 0.73 Tc(MIN.) = 14.23
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 14.00 = 1725.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 13.00 TO NODE 14.00 IS CODE = 81
----------------------------------------------------------------------------
>>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.926
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .7500
AREA-AVERAGE RUNOFF COEFFICIENT = 0.7319
SUBAREA AREA(ACRES) = 2.66 SUBAREA RUNOFF(CFS) = 5.84
TOTAL AREA(ACRES) = 9.6 TOTAL RUNOFF(CFS) = 20.56
TC(MIN.) = 14.23
****************************************************************************
FLOW PROCESS FROM NODE 14.00 TO NODE 15.00 IS CODE = 31
----------------------------------------------------------------------------
>>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<<
============================================================================
ELEVATION DATA: UPSTREAM(FEET) = 606.35 DOWNSTREAM(FEET) = 605.50
FLOW LENGTH(FEET) = 75.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 24.0 INCH PIPE IS 17.8 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 8.23
ESTIMATED PIPE DIAMETER(INCH) = 24.00 NUMBER OF PIPES = 1
PIPE-FLOW(CFS) = 20.56
PIPE TRAVEL TIME(MIN.) = 0.15 Tc(MIN.) = 14.38
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 15.00 = 1800.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 15.00 TO NODE 15.00 IS CODE = 10
----------------------------------------------------------------------------
>>>>>MAIN-STREAM MEMORY COPIED ONTO MEMORY BANK # 1 <<<<<
============================================================================
****************************************************************************
FLOW PROCESS FROM NODE 17.00 TO NODE 18.00 IS CODE = 21
----------------------------------------------------------------------------
>>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .6300
INITIAL SUBAREA FLOW-LENGTH(FEET) = 60.00
UPSTREAM ELEVATION(FEET) = 616.00
DOWNSTREAM ELEVATION(FEET) = 615.50
ELEVATION DIFFERENCE(FEET) = 0.50
URBAN SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.767
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN
THE MAXIMUM OVERLAND FLOW LENGTH = 56.67
Page 5
50PR.OUT
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION!
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.725
SUBAREA RUNOFF(CFS) = 0.30
TOTAL AREA(ACRES) = 0.10 TOTAL RUNOFF(CFS) = 0.30
****************************************************************************
FLOW PROCESS FROM NODE 18.00 TO NODE 19.00 IS CODE = 62
----------------------------------------------------------------------------
>>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 7 USED)<<<<<
============================================================================
UPSTREAM ELEVATION(FEET) = 615.50 DOWNSTREAM ELEVATION(FEET) = 614.30
STREET LENGTH(FEET) = 150.00 CURB HEIGHT(INCHES) = 6.0
STREET HALFWIDTH(FEET) = 12.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 5.00
INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 2
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 = 0.0150
**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 2.71
STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:
STREET FLOW DEPTH(FEET) = 0.29
HALFSTREET FLOOD WIDTH(FEET) = 7.98
AVERAGE FLOW VELOCITY(FEET/SEC.) = 1.79
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 0.51
STREET FLOW TRAVEL TIME(MIN.) = 1.39 Tc(MIN.) = 8.16
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.187
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .7900
AREA-AVERAGE RUNOFF COEFFICIENT = 0.780
SUBAREA AREA(ACRES) = 1.46 SUBAREA RUNOFF(CFS) = 4.83
TOTAL AREA(ACRES) = 1.6 PEAK FLOW RATE(CFS) = 5.09
END OF SUBAREA STREET FLOW HYDRAULICS:
DEPTH(FEET) = 0.34 HALFSTREET FLOOD WIDTH(FEET) = 10.55
FLOW VELOCITY(FEET/SEC.) = 2.07 DEPTH*VELOCITY(FT*FT/SEC.) = 0.70
LONGEST FLOWPATH FROM NODE 17.00 TO NODE 19.00 = 210.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 16.00 TO NODE 19.00 IS CODE = 81
----------------------------------------------------------------------------
>>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.187
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .7500
AREA-AVERAGE RUNOFF COEFFICIENT = 0.7589
SUBAREA AREA(ACRES) = 3.66 SUBAREA RUNOFF(CFS) = 11.49
TOTAL AREA(ACRES) = 5.2 TOTAL RUNOFF(CFS) = 16.59
TC(MIN.) = 8.16
****************************************************************************
FLOW PROCESS FROM NODE 19.00 TO NODE 15.00 IS CODE = 31
----------------------------------------------------------------------------
>>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<<
============================================================================
ELEVATION DATA: UPSTREAM(FEET) = 605.90 DOWNSTREAM(FEET) = 605.50
FLOW LENGTH(FEET) = 40.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 24.0 INCH PIPE IS 15.8 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 7.54
ESTIMATED PIPE DIAMETER(INCH) = 24.00 NUMBER OF PIPES = 1
PIPE-FLOW(CFS) = 16.59
PIPE TRAVEL TIME(MIN.) = 0.09 Tc(MIN.) = 8.25
LONGEST FLOWPATH FROM NODE 17.00 TO NODE 15.00 = 250.00 FEET.
Page 6
50PR.OUT
****************************************************************************
FLOW PROCESS FROM NODE 15.00 TO NODE 15.00 IS CODE = 11
----------------------------------------------------------------------------
>>>>>CONFLUENCE MEMORY BANK # 1 WITH THE MAIN-STREAM MEMORY<<<<<
============================================================================
** MAIN STREAM CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 16.59 8.25 4.158 5.22
LONGEST FLOWPATH FROM NODE 17.00 TO NODE 15.00 = 250.00 FEET.
** MEMORY BANK # 1 CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 20.56 14.38 2.906 9.60
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 15.00 = 1800.00 FEET.
** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 28.38 8.25 4.158
2 32.15 14.38 2.906
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:
PEAK FLOW RATE(CFS) = 32.15 Tc(MIN.) = 14.38
TOTAL AREA(ACRES) = 14.8
****************************************************************************
FLOW PROCESS FROM NODE 15.00 TO NODE 15.00 IS CODE = 12
----------------------------------------------------------------------------
>>>>>CLEAR MEMORY BANK # 1 <<<<<
============================================================================
****************************************************************************
FLOW PROCESS FROM NODE 15.00 TO NODE 20.00 IS CODE = 31
----------------------------------------------------------------------------
>>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<<
============================================================================
ELEVATION DATA: UPSTREAM(FEET) = 601.50 DOWNSTREAM(FEET) = 599.80
FLOW LENGTH(FEET) = 140.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 27.0 INCH PIPE IS 22.0 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 9.28
ESTIMATED PIPE DIAMETER(INCH) = 27.00 NUMBER OF PIPES = 1
PIPE-FLOW(CFS) = 32.15
PIPE TRAVEL TIME(MIN.) = 0.25 Tc(MIN.) = 14.63
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 20.00 = 1940.00 FEET.
+--------------------------------------------------------------------------+
| AREA NOT ROUTING TO THE DETENTION VAULT |
| |
| |
+--------------------------------------------------------------------------+
****************************************************************************
FLOW PROCESS FROM NODE 4.00 TO NODE 5.00 IS CODE = 21
----------------------------------------------------------------------------
>>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .7600
INITIAL SUBAREA FLOW-LENGTH(FEET) = 60.00
UPSTREAM ELEVATION(FEET) = 618.60
DOWNSTREAM ELEVATION(FEET) = 618.00
ELEVATION DIFFERENCE(FEET) = 0.60
URBAN SUBAREA OVERLAND TIME OF FLOW(MIN.) = 4.741
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN
THE MAXIMUM OVERLAND FLOW LENGTH = 60.00
(Reference: Table 3-1B of Hydrology Manual)
Page 7
50PR.OUT
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION!
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.744
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.
SUBAREA RUNOFF(CFS) = 0.17
TOTAL AREA(ACRES) = 0.04 TOTAL RUNOFF(CFS) = 0.17
****************************************************************************
FLOW PROCESS FROM NODE 5.00 TO NODE 6.00 IS CODE = 62
----------------------------------------------------------------------------
>>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 7 USED)<<<<<
============================================================================
UPSTREAM ELEVATION(FEET) = 618.00 DOWNSTREAM ELEVATION(FEET) = 616.50
STREET LENGTH(FEET) = 270.00 CURB HEIGHT(INCHES) = 6.0
STREET HALFWIDTH(FEET) = 12.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 5.00
INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 2
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 = 0.0150
**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 0.69
STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:
STREET FLOW DEPTH(FEET) = 0.21
HALFSTREET FLOOD WIDTH(FEET) = 4.12
AVERAGE FLOW VELOCITY(FEET/SEC.) = 1.20
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 0.25
STREET FLOW TRAVEL TIME(MIN.) = 3.76 Tc(MIN.) = 8.50
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.080
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .7800
AREA-AVERAGE RUNOFF COEFFICIENT = 0.778
SUBAREA AREA(ACRES) = 0.32 SUBAREA RUNOFF(CFS) = 1.02
TOTAL AREA(ACRES) = 0.4 PEAK FLOW RATE(CFS) = 1.14
END OF SUBAREA STREET FLOW HYDRAULICS:
DEPTH(FEET) = 0.24 HALFSTREET FLOOD WIDTH(FEET) = 5.67
FLOW VELOCITY(FEET/SEC.) = 1.30 DEPTH*VELOCITY(FT*FT/SEC.) = 0.31
LONGEST FLOWPATH FROM NODE 4.00 TO NODE 6.00 = 330.00 FEET.
****************************************************************************
FLOW PROCESS FROM NODE 21.00 TO NODE 22.00 IS CODE = 21
----------------------------------------------------------------------------
>>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .6500
INITIAL SUBAREA FLOW-LENGTH(FEET) = 60.00
UPSTREAM ELEVATION(FEET) = 627.60
DOWNSTREAM ELEVATION(FEET) = 627.00
ELEVATION DIFFERENCE(FEET) = 0.60
URBAN SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.274
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN
THE MAXIMUM OVERLAND FLOW LENGTH = 60.00
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION!
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.961
SUBAREA RUNOFF(CFS) = 0.32
TOTAL AREA(ACRES) = 0.10 TOTAL RUNOFF(CFS) = 0.32
****************************************************************************
FLOW PROCESS FROM NODE 22.00 TO NODE 23.00 IS CODE = 62
----------------------------------------------------------------------------
>>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 6 USED)<<<<<
============================================================================
UPSTREAM ELEVATION(FEET) = 627.00 DOWNSTREAM ELEVATION(FEET) = 617.60
Page 8
50PR.OUT
STREET LENGTH(FEET) = 560.00 CURB HEIGHT(INCHES) = 6.0
STREET HALFWIDTH(FEET) = 44.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 12.00
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) = 0.0150
Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150
**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 3.70
STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:
STREET FLOW DEPTH(FEET) = 0.34
HALFSTREET FLOOD WIDTH(FEET) = 10.58
AVERAGE FLOW VELOCITY(FEET/SEC.) = 2.98
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 1.01
STREET FLOW TRAVEL TIME(MIN.) = 3.13 Tc(MIN.) = 9.40
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.822
*USER SPECIFIED(SUBAREA):
PAVED SURFACE RUNOFF COEFFICIENT = .8400
AREA-AVERAGE RUNOFF COEFFICIENT = 0.831
SUBAREA AREA(ACRES) = 2.10 SUBAREA RUNOFF(CFS) = 6.74
TOTAL AREA(ACRES) = 2.2 PEAK FLOW RATE(CFS) = 6.99
END OF SUBAREA STREET FLOW HYDRAULICS:
DEPTH(FEET) = 0.40 HALFSTREET FLOOD WIDTH(FEET) = 13.74
FLOW VELOCITY(FEET/SEC.) = 3.48 DEPTH*VELOCITY(FT*FT/SEC.) = 1.40
LONGEST FLOWPATH FROM NODE 21.00 TO NODE 23.00 = 620.00 FEET.
============================================================================
END OF STUDY SUMMARY:
TOTAL AREA(ACRES) = 2.2 TC(MIN.) = 9.40
PEAK FLOW RATE(CFS) = 6.99
============================================================================
============================================================================
END OF RATIONAL METHOD ANALYSIS
Page 9
Otay Ranch Town Center
Drainage Study
CHAPTER 4
DETENTION VAULT ANALYSIS
RATIONAL METHOD HYDROGRAPH PROGRAM
COPYRIGHT 1992, 2001 RICK ENGINEERING COMPANY
RUN DATE 2/8/2023
HYDROGRAPH FILE NAME Text1
TIME OF CONCENTRATION 15 MIN.
6 HOUR RAINFALL 2.5 INCHES
BASIN AREA 14.82 ACRES
RUNOFF COEFFICIENT 0.7165
PEAK DISCHARGE 37.14 CFS
TIME (MIN) = 0 DISCHARGE (CFS) = 0
TIME (MIN) = 15 DISCHARGE (CFS) = 1.6
TIME (MIN) = 30 DISCHARGE (CFS) = 1.6
TIME (MIN) = 45 DISCHARGE (CFS) = 1.7
TIME (MIN) = 60 DISCHARGE (CFS) = 1.8
TIME (MIN) = 75 DISCHARGE (CFS) = 1.9
TIME (MIN) = 90 DISCHARGE (CFS) = 2
TIME (MIN) = 105 DISCHARGE (CFS) = 2.2
TIME (MIN) = 120 DISCHARGE (CFS) = 2.3
TIME (MIN) = 135 DISCHARGE (CFS) = 2.5
TIME (MIN) = 150 DISCHARGE (CFS) = 2.7
TIME (MIN) = 165 DISCHARGE (CFS) = 3.1
TIME (MIN) = 180 DISCHARGE (CFS) = 3.3
TIME (MIN) = 195 DISCHARGE (CFS) = 4.1
TIME (MIN) = 210 DISCHARGE (CFS) = 4.6
TIME (MIN) = 225 DISCHARGE (CFS) = 6.8
TIME (MIN) = 240 DISCHARGE (CFS) = 6.9
TIME (MIN) = 255 DISCHARGE (CFS) = 37.14
TIME (MIN) = 270 DISCHARGE (CFS) = 5.5
TIME (MIN) = 285 DISCHARGE (CFS) = 3.7
TIME (MIN) = 300 DISCHARGE (CFS) = 2.9
TIME (MIN) = 315 DISCHARGE (CFS) = 2.4
TIME (MIN) = 330 DISCHARGE (CFS) = 2.1
TIME (MIN) = 345 DISCHARGE (CFS) = 1.9
TIME (MIN) = 360 DISCHARGE (CFS) = 1.7
TIME (MIN) = 375 DISCHARGE (CFS) = 0
Otay Ranch Town Center
Drainage Study
Vault – Stage Information
Stage – Storage
Stage- Discharge
Vault HMP\ Detention\ WQ
Discharge vs Elevation Table
Bottom orifice diameter:3.50 "Top orifice diameter:4 "
Number:1 Number:0
Cg-low:0.61 Cg-low:0.61
invert elev:0.00 ft invert elev:3.00 ft
Middle orifice diameter:3.0 "Emergency weir:
number of orif:0 Invert:3.00 ft
Cg-middle:0.61 Weir Length (ft)10.0 ft
invert elev:2.50 ft Box riser 2' x 3'
h H/D-low H/D-mid H/D-top H/D-peak Qlow-orif Qlow-weir Qtot-low Qmid-orif Qmid-weir Qtot-med Qtop-orif Qtop-weir Qtot-top Qpeak-top Qtot
(ft)----(cfs)(cfs)(cfs)(cfs)(cfs)(cfs)(cfs)(cfs)(cfs)(cfs)(cfs)
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0000
0.25 0.86 0.00 0.00 0.00 0.11 0.09 0.09 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0924
0.50 1.71 0.00 0.00 0.00 0.19 0.25 0.19 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.1946
0.75 2.57 0.00 0.00 0.00 0.25 0.32 0.25 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.2542
1.00 3.43 0.00 0.00 0.00 0.30 0.35 0.30 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.3023
1.25 4.29 0.00 0.00 0.00 0.34 0.78 0.34 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.3437
1.50 5.14 0.00 0.00 0.00 0.38 2.67 0.38 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.3806
1.75 6.00 0.00 0.00 0.00 0.41 7.88 0.41 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.4142
2.00 6.86 0.00 0.00 0.00 0.45 19.28 0.45 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.4454
2.25 7.71 0.00 0.00 0.00 0.47 40.97 0.47 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.4744
2.50 8.57 0.00 0.00 0.00 0.50 78.48 0.50 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.5018
2.75 9.43 1.00 0.00 0.00 0.53 138.93 0.53 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.5278
3.00 10.29 2.00 0.00 0.00 0.55 231.32 0.55 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.5526
3.25 11.14 3.00 0.75 0.30 0.58 366.64 0.58 0.00 0.00 0.00 0.00 0.00 0.00 4.16 4.7387
3.50 12.00 4.00 1.50 0.60 0.60 558.16 0.60 0.00 0.00 0.00 0.00 0.00 0.00 11.77 12.3723
3.75 12.86 5.00 2.25 0.90 0.62 821.57 0.62 0.00 0.00 0.00 0.00 0.00 0.00 21.63 22.2499
4.00 13.71 6.00 3.00 1.20 0.64 1175.20 0.64 0.00 0.00 0.00 0.00 0.00 0.00 33.30 33.9421
4.25 14.57 7.00 3.75 1.50 0.66 1640.27 0.66 0.00 0.00 0.00 0.00 0.00 0.00 46.54 47.2008
4.50 15.43 8.00 4.50 1.80 0.68 2241.01 0.68 0.00 0.00 0.00 0.00 0.00 0.00 61.18 61.8585
4.75 16.29 9.00 5.25 2.10 0.70 3004.94 0.70 0.00 0.00 0.00 0.00 0.00 0.00 77.09 77.7924
5.00 17.14 10.00 6.00 2.40 0.72 3963.05 0.72 0.00 0.00 0.00 0.00 0.00 0.00 94.19 94.9072
5.25 18.00 11.00 6.75 2.70 0.74 5149.97 0.74 0.00 0.00 0.00 0.00 0.00 0.00 112.39 113.1264
5.50 18.86 12.00 7.50 3.00 0.76 6604.23 0.76 0.00 0.00 0.00 0.00 0.00 0.00 131.63 132.3866
Stage Storage Vault HMP-1
Depth
(ft)
Area
(sq ft)
Volume
(cu ft)
Volume
Total
(cu ft)
Storage
(ac-ft)
0.00 16800 0
0.25 16800 4,200 4,200 0.096419
0.50 16800 4,200 8,400 0.192837
0.75 16800 4,200 12,600 0.289256
1.00 16800 4,200 16,800 0.385675
1.25 16800 4,200 21,000 0.482094
1.50 16800 4,200 25,200 0.578512
1.75 16800 4,200 29,400 0.674931
2.00 16800 4,200 33,600 0.77135
2.25 16800 4,200 37,800 0.867769
2.50 16800 4,200 42,000 0.964187
2.75 16800 4,200 46,200 1.060606
3.00 16800 4,200 50,400 1.157025
3.25 16800 4,200 54,600 1.253444
3.50 16800 4,200 58,800 1.349862
3.75 16800 4,200 63,000 1.446281
4.00 16800 4,200 67,200 1.5427
4.25 16800 4,200 71,400 1.639118
4.50 16800 4,200 75,600 1.735537
4.75 16800 4,200 79,800 1.831956
5.00 16800 4,200 84,000 1.928375
5.25 16800 4,200 88,200 2.024793
5.50 16800 4,200 92,400 2.121212
Elevation QAVG (CFS)DV (CF)DT (HR)Total T
0.00
0.25 0.0924 4200.0 12.6212 48.58
0.50 0.1946 4200.0 5.9939 35.96
0.75 0.2542 4200.0 4.5891 29.97
1.00 0.3023 4200.0 3.8596 25.38
1.25 0.3437 4200.0 3.3946 21.52
1.50 0.3806 4200.0 3.0653 18.12
1.75 0.4142 4200.0 2.8163 15.06
2.00 0.4454 4200.0 2.6196 12.24
2.25 0.4744 4200.0 2.4591 9.62
2.50 0.5018 4200.0 2.3248 7.16
2.75 0.5278 4200.0 2.2104 4.84
3.00 0.5526 4200.0 2.1114 2.63
3.25 4.7387 4200.0 0.2462 0.52
3.50 12.3723 4200.0 0.0943 0.27
3.75 22.2499 4200.0 0.0524 0.18
4.00 33.9421 4200.0 0.0344 0.12
4.25 47.2008 4200.0 0.0247 0.09
4.50 61.8585 4200.0 0.0189 0.07
4.75 77.7924 4200.0 0.0150 0.05
5.00 94.9072 4200.0 0.0123 0.03
5.25 113.1264 4200.0 0.0103 0.02
5.50 132.3866 4200.0 0.0088 0.01
Draw Down
Otay Ranch Town Center
Drainage Study
100-YEAR DETENTION
HEC-HMS INPUT
HEC-HMS RESULTS
Otay Ranch Town Center
Drainage Study
CHAPTER 5
PRELIMINARY DESILT BASIN CALCULATIONS
PROJECT NAME Otay Town Center
WORK ORDER 3553-0002
SEDIMENT BASIN Basin 1 : Node 11
Per Option 3, Part 8 of Section A of the State Water Resources Control Board Order
No. 99-08-DWQ, sediment basins shall, at a minimum, be designed as follows:
Sediment basins shall be designed using the standard equation:
AS = 1.2Q
VS
Where A S is the minimum surface area for trapping soil particles of a certain size;
V S is the settling velocity of the design particle size chosen; and Q=CIA where
Q is the average discharge rate measured in cfs;I is the average precipitation intensity
for the 10-year, 6-hour rain event; and A is the area draining into the sediment basin
in acres.
The design particle size shall be the smallest soil grain size determined by wet sieve
analysis, or the fine silt sized (0.01 mm) particle, and the V S used shall be 100 percent
of the calculated settling velocity.
The length is determined by measuring the distance between the inlet and the outlet;
the length shall be more than twice the dimension as the width; the depth shall not be less
than three feet nor greater than five feet for safety reasons and for maximum efficiency
(two feet of storage, two feet of capacity between storage area and riser). The basin
shall be located on the site where it can be maintained on a schedule to retain the
two feet of capacity.
TOTAL AREA DRAINING TO BASIN ------------>3.45 acres
WEIGHTED RUNOFF COEFFICIENT ------------>0.35
10-YEAR, 6-HOUR RAINFALL ------------>1.55 inches (from County Isopluvial Map)
AVG. RAINFALL INTENSITY 0.26 in/hr
10-YEAR AVERAGE FLOW 0.3 cfs
FINE SILT PARTICLE SIZE 0.01 mm (per Option 3 criteria - see above)
SETTLING VELOCITY 0.00024 ft/sec (per Table 8.1 - see below)
MINIMUM SURFACE AREA AT 1560 ft2
BASE OF THE SEDIMENT BASIN or
0.04 acres
BASIN LENGTH AT BASE 57 feet (Basin Length >= 2 * Basin Width)
BASIN WIDTH AT BASE 28 feet
BASIN BASE SURFACE AREA 1588 ft2 >= Minimum Base Surface Area
or
0.04 acres
REQUIRED SEDIMENT STORAGE ------------>46.575 CY (per Table 5-1 - see below)
1258 ft3
0.03 acre-ft
BOTTOM OF BASIN ELEVATION ------------->615 feet
TOP OF SEDIMENT STORAGE AREA ------------->616.5 feet (assume 1.5 feet of sediment vol)
SEDIMENT STORAGE DEPTH 1.5 feet (assume 2:1 basin side slopes)
SEDIMENT STORAGE CAPACITY 2776 ft3 > Required Sediment Storage
or
103 CY
or
0.06 acre-ft
TOP OF RISER ELEVATION 618.5 feet (provide 2 feet above sediment)
BASIN DEPTH BELOW RISER 3.5 feet (3 <= Depth <= 5 feet)
BASIN VOLUME UNDER RISER 7805 ft3
or
289 CY
or
0.18 acre-ft
100-YEAR PEAK FLOW TO BASIN ------------>7.95 cfs (from Hydrology Study)
100-YEAR HW OVER RISER ------------->1.21 feet (from riser inlet spreadsheet)
100-YEAR WSE OVER RISER 619.71 feet
REQUIRED FREEBOARD OVER ------------->1 ft.
100-YEAR WSE
TOP OF BASIN ELEVATION ------------->620.7 feet
* Emergency spillway crest elevation shall be set at or above 100-Year WSE. The emergency
spillway shall be sized to convey the 100-year runoff assuming 100% clogging of principle spillway.
FOR BROAD-CRESTED EMERGENCY SPILLWAY WEIRS:
If the SPILLWAY OPENING =------------->5 feet
Then the Crest Elevation Must Be =620.0 feet
If the CREST ELEVATION =------------->619.7 feet
Then the Spillway Opening Must Be =3.02 feet
* TABLE 8.1 is from the "Erosion & Sediment Control Handbook" by Steven J. Goldman, Katharine
Jackson, and Taras A. Bursztynsky; McGraw-Hill Book Company; 1986.
** TABLE 5-1 is from the "San Diego County Hydrology Manual (Draft)" prepared by the County of
San Diego Department of Public Works - Flood Control Section; September 2001.
PROJECT NAME Otay Town Center
WORK ORDER 3553-0002
SEDIMENT BASIN Basin 2 : Node 13
Per Option 3, Part 8 of Section A of the State Water Resources Control Board Order
No. 99-08-DWQ, sediment basins shall, at a minimum, be designed as follows:
Sediment basins shall be designed using the standard equation:
AS = 1.2Q
VS
Where A S is the minimum surface area for trapping soil particles of a certain size;
V S is the settling velocity of the design particle size chosen; and Q=CIA where
Q is the average discharge rate measured in cfs;I is the average precipitation intensity
for the 10-year, 6-hour rain event; and A is the area draining into the sediment basin
in acres.
The design particle size shall be the smallest soil grain size determined by wet sieve
analysis, or the fine silt sized (0.01 mm) particle, and the V S used shall be 100 percent
of the calculated settling velocity.
The length is determined by measuring the distance between the inlet and the outlet;
the length shall be more than twice the dimension as the width; the depth shall not be less
than three feet nor greater than five feet for safety reasons and for maximum efficiency
(two feet of storage, two feet of capacity between storage area and riser). The basin
shall be located on the site where it can be maintained on a schedule to retain the
two feet of capacity.
TOTAL AREA DRAINING TO BASIN ------------>2.66 acres
WEIGHTED RUNOFF COEFFICIENT ------------>0.35
10-YEAR, 6-HOUR RAINFALL ------------>1.55 inches (from County Isopluvial Map)
AVG. RAINFALL INTENSITY 0.26 in/hr
10-YEAR AVERAGE FLOW 0.2 cfs
FINE SILT PARTICLE SIZE 0.01 mm (per Option 3 criteria - see above)
SETTLING VELOCITY 0.00024 ft/sec (per Table 8.1 - see below)
MINIMUM SURFACE AREA AT 1203 ft2
BASE OF THE SEDIMENT BASIN or
0.03 acres
BASIN LENGTH AT BASE 50 feet (Basin Length >= 2 * Basin Width)
BASIN WIDTH AT BASE 25 feet
BASIN BASE SURFACE AREA 1227 ft2 >= Minimum Base Surface Area
or
0.03 acres
REQUIRED SEDIMENT STORAGE ------------>35.91 CY (per Table 5-1 - see below)
970 ft3
0.02 acre-ft
BOTTOM OF BASIN ELEVATION ------------->611.1 feet
TOP OF SEDIMENT STORAGE AREA ------------->612.1 feet (assume 1 feet of sediment vol)
SEDIMENT STORAGE DEPTH 1 feet (assume 2:1 basin side slopes)
SEDIMENT STORAGE CAPACITY 1380 ft3 > Required Sediment Storage
or
51 CY
or
0.03 acre-ft
TOP OF RISER ELEVATION 614.1 feet (provide 2 feet above sediment)
BASIN DEPTH BELOW RISER 3 feet (3 <= Depth <= 5 feet)
BASIN VOLUME UNDER RISER 5131 ft3
or
190 CY
or
0.12 acre-ft
100-YEAR PEAK FLOW TO BASIN ------------>6.13 cfs (from Hydrology Study)
100-YEAR HW OVER RISER ------------->0.72 feet (from riser inlet spreadsheet)
100-YEAR WSE OVER RISER 614.82 feet
REQUIRED FREEBOARD OVER ------------->1 ft.
100-YEAR WSE
TOP OF BASIN ELEVATION ------------->615.8 feet
* Emergency spillway crest elevation shall be set at or above 100-Year WSE. The emergency
spillway shall be sized to convey the 100-year runoff assuming 100% clogging of principle spillway.
FOR BROAD-CRESTED EMERGENCY SPILLWAY WEIRS:
If the SPILLWAY OPENING =------------->5 feet
Then the Crest Elevation Must Be =615.2 feet
If the CREST ELEVATION =------------->614.8 feet
Then the Spillway Opening Must Be =2.31 feet
* TABLE 8.1 is from the "Erosion & Sediment Control Handbook" by Steven J. Goldman, Katharine
Jackson, and Taras A. Bursztynsky; McGraw-Hill Book Company; 1986.
** TABLE 5-1 is from the "San Diego County Hydrology Manual (Draft)" prepared by the County of
San Diego Department of Public Works - Flood Control Section; September 2001.
PROJECT NAME Otay Town Center
WORK ORDER 3553-0002
SEDIMENT BASIN Basin 3 : Node 7
Per Option 3, Part 8 of Section A of the State Water Resources Control Board Order
No. 99-08-DWQ, sediment basins shall, at a minimum, be designed as follows:
Sediment basins shall be designed using the standard equation:
AS = 1.2Q
VS
Where A S is the minimum surface area for trapping soil particles of a certain size;
V S is the settling velocity of the design particle size chosen; and Q=CIA where
Q is the average discharge rate measured in cfs;I is the average precipitation intensity
for the 10-year, 6-hour rain event; and A is the area draining into the sediment basin
in acres.
The design particle size shall be the smallest soil grain size determined by wet sieve
analysis, or the fine silt sized (0.01 mm) particle, and the V S used shall be 100 percent
of the calculated settling velocity.
The length is determined by measuring the distance between the inlet and the outlet;
the length shall be more than twice the dimension as the width; the depth shall not be less
than three feet nor greater than five feet for safety reasons and for maximum efficiency
(two feet of storage, two feet of capacity between storage area and riser). The basin
shall be located on the site where it can be maintained on a schedule to retain the
two feet of capacity.
TOTAL AREA DRAINING TO BASIN ------------>0.44 acres
WEIGHTED RUNOFF COEFFICIENT ------------>0.35
10-YEAR, 6-HOUR RAINFALL ------------>1.55 inches (from County Isopluvial Map)
AVG. RAINFALL INTENSITY 0.26 in/hr
10-YEAR AVERAGE FLOW 0.04 cfs
FINE SILT PARTICLE SIZE 0.01 mm (per Option 3 criteria - see above)
SETTLING VELOCITY 0.00024 ft/sec (per Table 8.1 - see below)
MINIMUM SURFACE AREA AT 199 ft2
BASE OF THE SEDIMENT BASIN or
0.00 acres
BASIN LENGTH AT BASE 21 feet (Basin Length >= 2 * Basin Width)
BASIN WIDTH AT BASE 10 feet
BASIN BASE SURFACE AREA 209 ft2 >= Minimum Base Surface Area
or
0.00 acres
REQUIRED SEDIMENT STORAGE ------------>5.94 CY (per Table 5-1 - see below)
160 ft3
0.00 acre-ft
BOTTOM OF BASIN ELEVATION ------------->612.6 feet
TOP OF SEDIMENT STORAGE AREA ------------->613.6 feet (assume 1 feet of sediment vol)
SEDIMENT STORAGE DEPTH 1 feet (assume 2:1 basin side slopes)
SEDIMENT STORAGE CAPACITY 275 ft3 > Required Sediment Storage
or
10 CY
or
0.01 acre-ft
TOP OF RISER ELEVATION 615.6 feet (provide 2 feet above sediment)
BASIN DEPTH BELOW RISER 3 feet (3 <= Depth <= 5 feet)
BASIN VOLUME UNDER RISER 1291 ft3
or
48 CY
or
0.03 acre-ft
100-YEAR PEAK FLOW TO BASIN ------------>1.01 cfs (from Hydrology Study)
100-YEAR HW OVER RISER ------------->0.16 feet (from riser inlet spreadsheet)
100-YEAR WSE OVER RISER 615.76 feet
REQUIRED FREEBOARD OVER ------------->1 ft.
100-YEAR WSE
TOP OF BASIN ELEVATION ------------->616.8 feet
* Emergency spillway crest elevation shall be set at or above 100-Year WSE. The emergency
spillway shall be sized to convey the 100-year runoff assuming 100% clogging of principle spillway.
FOR BROAD-CRESTED EMERGENCY SPILLWAY WEIRS:
If the SPILLWAY OPENING =------------->5 feet
Then the Crest Elevation Must Be =616.6 feet
If the CREST ELEVATION =------------->615.8 feet
Then the Spillway Opening Must Be =0.38 feet
* TABLE 8.1 is from the "Erosion & Sediment Control Handbook" by Steven J. Goldman, Katharine
Jackson, and Taras A. Bursztynsky; McGraw-Hill Book Company; 1986.
** TABLE 5-1 is from the "San Diego County Hydrology Manual (Draft)" prepared by the County of
San Diego Department of Public Works - Flood Control Section; September 2001.
PROJECT NAME Otay Town Center
WORK ORDER 3553-0002
SEDIMENT TRAP Sediment Trap: Node 16
Per Section SE-3 (Sediment Trap) of the California Stormwater BMP Handbook, Sediment Traps
may be used on construction projects where the drainage area is less than 5 acres.
Trap should be sized to accommodate a settling zone and a sediment storage zone with a
recommended minimum cvolumes of 67 CY/acre and 33 CY/acre of contributing drainage
area, respectively, based ona 0.5 in. of runoff volume over a 24-hour period.
GRADED AREA TO BASIN ------------>3.66 acres
100-YEAR PEAK FLOW TO BASIN ------------>8.44 cfs
REQUIRED STORAGE CAPACITY 9882 ft3
BELOW PRINCIPLE OUTLET ELEV.366 CY
0.23 acre-ft.
BOTTOM OF BASIN ELEVATION ------------->610.1 feet
PRINCIPLE SPILLWAY EL.------------->613.6 feet
DEPTH BELOW PRINCIPLE OUTLET 3.5 feet
DESIGN BASIN BOTTOM WIDTH ------------->30 feet
DESIGN BASIN BOTTOM LENGTH 61 feet (Length > = 2 * Width)
DESIGN STORAGE CAPACITY 10135 ft3 (Assume 3:1 Basin Side Slopes)
BELOW PRINCIPLE OUTET ELEV.375 CY
0.23 acre-ft.
FREEBOARD ABOVE ------------->1 ft.
100-YEAR WSE
TOP OF BASIN ELEVATION ------------->614.6 feet
FOR BROAD-CRESTED EMERGENCY SPILLWAY WEIRS:
If the SPILLWAY OPENING =------------->5 feet
Then the Crest Elevation Must Be =613.86 feet
If the CREST ELEVATION =------------->613.60 feet Use 4.0' wide spillway
Then the Spillway Opening Must Be =3.18 feet at Elev 3.5
*• Restrict basin side slopes to 3:1 or flatter
*Any water standing for more than 72 hours will be pumped out of the basin and dispersed throughout
the project over pervious areas and/or filtered and discharged to the storm drain system
Otay Town Center
DESILTING BASIN RISER SIZES
Weir Formula for Orifices & Short Tubes (free & submerged)
Q = Ca(2gh)0.5(0.85), where 0.85 is a reduction factor for trash rack
Q = 0.6a(64.32h)0.5(0.85); C = 0.6 from Table 4-10, Kings Handbook
Q = 4.1a(h)0.5, where a = area of orifice opening, h = head (ft) above top of riser
then h = (Q/4.1a)2 (Equation 1)
Weir Formula for riser acting as straight weir
Q = CLH1.5; C = 3.3 from Equation 5-40, Kings Handbook
then h = (Q/3.3L)2/3 (Equation 2)
Basin 1
@ Node 11 :
Q100 =7.95 cfs
Riser d =18 in., so a =1.767 sq. ft.; h =1.21 ft. (Equation 1)
L =4.712 ft.; h =0.64 ft. (Equation 2)
therefore:h =1.21 ft.
Basin 2
@ Node 13 :
Q100 =6.13 cfs
Riser d =18 in., so a =1.767 sq. ft.; h =0.72 ft. (Equation 1)
L =4.712 ft.; h =0.538 ft. (Equation 2)
therefore:h =0.72 ft.
Basin 3
@ Node 13 :
Q100 =1.01 cfs
Riser d =18 in., so a =1.767 sq. ft.; h =0.02 ft. (Equation 1)
L =4.712 ft.; h =0.162 ft. (Equation 2)
therefore:h =0.16 ft.
/1643-Desilt Basin.xls
2/8/2023
MASS GRADING HYDROLOGY
Flows to Basin 1
100 YEAR DEVELOPED CONDITIONS HYDROLOGIC ANALYSIS
PER COUNTY OF SD ISOPLUVIAL MAPS - P6 100 =2.5 in
Assume Minimum Allowable TC per San Diego County Methodology - TC =5.00 mins
Intensity -i =7.44P6D^-0.645 (San Diego County Hydrology Manual)
Therefore -i =6.59 in/hr
Using Rational Method - Q = CiA
Runoff Coefficients per San Diego County Criteria
Paved Areas =0.82 (type D soil onsite)
Open Space/Natural Area =0.35 (type D soil onsite)
Max Tributary Area
Mass Graded Pad Basin 1
A =150282 sqft Therefore
A =3.45 acres Q = CIA
i =6.59 in/hr Runoff =7.95 cfs
C =0.35
MASS GRADING HYDROLOGY
Flows to Basin 2
100 YEAR DEVELOPED CONDITIONS HYDROLOGIC ANALYSIS
PER COUNTY OF SD ISOPLUVIAL MAPS - P6 100 =2.5 in
Assume Minimum Allowable TC per San Diego County Methodology - TC =5.00 mins
Intensity -i =7.44P6D^-0.645 (San Diego County Hydrology Manual)
Therefore -i =6.59 in/hr
Using Rational Method - Q = CiA
Runoff Coefficients per San Diego County Criteria
Paved Areas =0.82 (type D soil onsite)
Open Space/Natural Area =0.35 (type D soil onsite)
Max Tributary Area
Mass Graded Pad Basin 1
A =115870 sqft Therefore
A =2.66 acres Q = CIA
i =6.59 in/hr Runoff =6.13 cfs
C =0.35
MASS GRADING HYDROLOGY
Flows to Basin 3
100 YEAR DEVELOPED CONDITIONS HYDROLOGIC ANALYSIS
PER COUNTY OF SD ISOPLUVIAL MAPS - P6 100 =2.5 in
Assume Minimum Allowable TC per San Diego County Methodology - TC =5.00 mins
Intensity -i =7.44P6D^-0.645 (San Diego County Hydrology Manual)
Therefore -i =6.59 in/hr
Using Rational Method - Q = CiA
Runoff Coefficients per San Diego County Criteria
Paved Areas =0.82 (type D soil onsite)
Open Space/Natural Area =0.35 (type D soil onsite)
Max Tributary Area
Mass Graded Pad Basin 1
A =19166 sqft Therefore
A =0.44 acres Q = CIA
i =6.59 in/hr Runoff =1.01 cfs
C =0.35
MASS GRADING HYDROLOGY
Flows to Sediment Trap
100 YEAR DEVELOPED CONDITIONS HYDROLOGIC ANALYSIS
PER COUNTY OF SD ISOPLUVIAL MAPS - P6 100 =2.5 in
Assume Minimum Allowable TC per San Diego County Methodology - TC =5.00 mins
Intensity -i =7.44P6D^-0.645 (San Diego County Hydrology Manual)
Therefore -i =6.59 in/hr
Using Rational Method - Q = CiA
Runoff Coefficients per San Diego County Criteria
Paved Areas =0.82 (type D soil onsite)
Open Space/Natural Area =0.35 (type D soil onsite)
Max Tributary Area
Mass Graded Pad Basin 1
A =159430 sqft Therefore
A =3.66 acres Q = CIA
i =6.59 in/hr Runoff =8.44 cfs
C =0.35
Otay Town Center
LS Factor Determination
0 1 2 5 8 10 12 15
0 0 0 0 0 0 0 0 0
0.44 0 5.94 11.88 15.4 16.28 17.6 19.8 22 Basin 3
2.66 0 35.91 71.82 93.1 98.42 106.4 119.7 133 Basin 2
3.45 0 46.575 93.15 120.75 127.65 138 155.25 172.5 Basin 1
10 0 135 270 350 370 400 450 500
15 0 200 400 420 460 600 675 750
20 0 270 540 700 740 800 900 1000
40 0 540 1080 1400 1480 1600 1800 2000
80 0 1080 2160 2800 2960 3200 3600 4000
100 0 1350 2700 3500 3700 4000 4500 5000
150 0 2000 4000 4200 4600 6000 6750 7500
200 0 2700 5400 7000 7400 8000 9000 10000
Tract
Area
(acres)
AVERAGE WATERSHED SLOPE (%)
2/8/2023
R:\1643\Hyd\TM\DR\Calcs\Excel\1643-Desilt Basin.xls
Otay Ranch Town Center
Drainage Study
CHAPTER 6
EXHIBIT 1
EXISTING CONDITION
HYDROLOGY MAP
EXHIBIT 2
DEVELOPED CONDITION
HYDROLOGY MAP
EXHIBIT 3
OVERLAY OF FLOOD INSURANCE RATE MAP
OF
2
1
MAP
PREPARED BY:
CITY OF CHULA VISTA, CALIFORNIA
OTAY TOWN CENTER
EXISTING DRAINAGE MAPHUNSAKER& ASSOCIATES
PROJECT BOUNDARY
DRAINAGE BOUNDARY
DAYLIGHT
INITIAL SUBAREA
FLOW DIRECTION
AREA
EX. STORM DRAIN
HYDROLOGIC SOIL TYPE
NODE NUMBER
EXISTING PAVED AREA
LEGEND
LOT 1
LOT AREA:1.50 AC.
PAD AREA:1.45 AC.
R-3
LOT AREA:5.32 AC.
PAD AREA:3.78 AC.
LOT E
LOT AREA:0.74 AC.
PAD AREA:0.71 AC.
NORTH AVE.
T
O
W
N
C
E
N
T
E
R
D
R
.
(
N
O
R
T
H
B
O
U
N
D
)
T
O
W
N
C
E
N
T
E
R
D
R
.
(
S
O
U
T
H
B
O
U
N
D
)
2N
D
S
T
R
E
E
T
LOT 2
LOT AREA:1.18 AC.
PAD AREA:1.10 AC.
LOT 3
LOT AREA:1.81 AC.
PAD AREA:1.71 AC.
LOT 4
LOT AREA:1.81 AC.
PAD AREA:1.63 AC.
LOT 9
LOT AREA:0.47 AC.
PAD AREA:0.42 AC.
LOT 6
LOT AREA:0.73 AC.
PAD AREA:0.69 AC.
LOT 8
LOT AREA:1.17 AC.
PAD AREA:1.13 AC.
LOT 7
LOT AREA:1.19 AC.
PAD AREA:1.14 AC.
LOT 5
LOT AREA:0.73 AC.
PAD AREA:0.69 AC.
OF
2
2
MAP
PREPARED BY:
CITY OF CHULA VISTA, CALIFORNIA
OTAY TOWN CENTER
PROPOSED DRAINAGE MAPHUNSAKER& ASSOCIATES
PROJECT BOUNDARY
DRAINAGE BOUNDARY
DAYLIGTH
INITIAL SUBAREA
PROPOSED STORM DRAIN
EXISTING STORM DRAIN
FLOW DIRECTION
AREA
HYDROLOGIC SOIL TYPE
NODE NUMBER
EXISTING IMPERVIOUS
LEGEND
National Flood Hazard Layer FIRMette
0 500 1,000 1,500 2,000250
Feet
Ü
SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT
SPECIAL FLOOD
HAZARD AREAS
Without Base Flood Elevation (BFE)
Zone A, V, A99
With BFE or DepthZone AE, AO, AH, VE, AR
Regulatory Floodway
0.2% Annual Chance Flood Hazard, Areas
of 1% annual chance flood with average
depth less than one foot or with drainage
areas of less than one square mileZone X
Future Conditions 1% Annual
Chance Flood HazardZone X
Area with Reduced Flood Risk due to
Levee. See Notes.Zone X
Area with Flood Risk due to LeveeZone D
NO SCREEN Area of Minimal Flood Hazard Zone X
Area of Undetermined Flood HazardZone D
Channel, Culvert, or Storm Sewer
Levee, Dike, or Floodwall
Cross Sections with 1% Annual Chance
17.5 Water Surface Elevation
Coastal Transect
Coastal Transect Baseline
Profile Baseline
Hydrographic Feature
Base Flood Elevation Line (BFE)
Effective LOMRs
Limit of Study
Jurisdiction Boundary
Digital Data Available
No Digital Data Available
Unmapped
This map complies with FEMA's standards for the use of
digital flood maps if it is not void as described below.
The basemap shown complies with FEMA's basemap
accuracy standards
The flood hazard information is derived directly from the
authoritative NFHL web services provided by FEMA. This map
was exported on 1/24/2021 at 2:04 AM and does not
reflect changes or amendments subsequent to this date and
time. The NFHL and effective information may change or
become superseded by new data over time.
This map image is void if the one or more of the following map
elements do not appear: basemap imagery, flood zone labels,
legend, scale bar, map creation date, community identifiers,
FIRM panel number, and FIRM effective date. Map images for
unmapped and unmodernized areas cannot be used for
regulatory purposes.
Legend
OTHER AREAS OF
FLOOD HAZARD
OTHER AREAS
GENERAL
STRUCTURES
OTHER
FEATURES
MAP PANELS
8
B 20.2
The pin displayed on the map is an approximate
point selected by the user and does not represent
an authoritative property location.
1:6,000
116°58'31"W 32°37'48"N
116°57'53"W 32°37'18"N
Basemap: USGS National Map: Orthoimagery: Data refreshed October, 2020