2025-10-21; City Council; 05; Adoption of Plans, Specifications, Contract Documents, Authorization to Advertise for Bids for the Veterans Memorial Park Project and the Faraday Avenue Improvements Proj — Carlsbad City Council, October 21, 2025 (part 11 of 21)

**************************************************************************** FLOW PROCESS FROM NODE 5.08 TO NODE 5.08 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 6.42 9.73 2.058 8.47
LONGEST FLOWPATH FROM NODE 5.09 TO NODE 5.08 = 1275.00 FEET.

** MEMORY BANK # 1 CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 17.64 14.30 1.606 30.26
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.08 = 2115.00 FEET.

** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 18.43 9.73 2.058
2 22.65 14.30 1.606

COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 22.65 Tc(MIN.) = 14.30
TOTAL AREA(ACRES) = 38.7

**************************************************************************** FLOW PROCESS FROM NODE 5.08 TO NODE 5.08 IS CODE = 12 ---------------------------------------------------------------------------- >>>>>CLEAR MEMORY BANK # 1 <<<<<
============================================================================

**************************************************************************** FLOW PROCESS FROM NODE 5.08 TO NODE 5.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 90.00 DOWNSTREAM(FEET) = 72.60 FLOW LENGTH(FEET) = 150.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 15.0 INCH PIPE IS 11.1 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 23.35
ESTIMATED PIPE DIAMETER(INCH) = 15.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 22.65
PIPE TRAVEL TIME(MIN.) = 0.11 Tc(MIN.) = 14.40
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.20 = 2265.00 FEET.

…VMP - Hydrology & Hydraulic Report - Final.docx page 28

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
>>>>>MAIN-STREAM MEMORY COPIED ONTO MEMORY BANK # 1 <<<<< ============================================================================

**************************************************************************** FLOW PROCESS FROM NODE 5.16 TO NODE 5.17 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ LAWNS, GOLF COURSES, ETC. GOOD COVER RUNOFF COEFFICIENT = .3500 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 80
INITIAL SUBAREA FLOW-LENGTH(FEET) = 170.00
UPSTREAM ELEVATION(FEET) = 155.00
DOWNSTREAM ELEVATION(FEET) = 129.50
ELEVATION DIFFERENCE(FEET) = 25.50
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 100.00
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 2 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.733
SUBAREA RUNOFF(CFS) = 0.12
TOTAL AREA(ACRES) = 0.13 TOTAL RUNOFF(CFS) = 0.12

**************************************************************************** FLOW PROCESS FROM NODE 5.17 TO NODE 5.18 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 126.50 DOWNSTREAM(FEET) = 81.30 FLOW LENGTH(FEET) = 550.00 MANNING'S N = 0.011
ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 4.000
DEPTH OF FLOW IN 4.0 INCH PIPE IS 1.2 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 5.55
ESTIMATED PIPE DIAMETER(INCH) = 4.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 0.12
PIPE TRAVEL TIME(MIN.) = 1.65 Tc(MIN.) = 7.92
LONGEST FLOWPATH FROM NODE 5.16 TO NODE 5.18 = 720.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.18 TO NODE 5.18 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 2 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.350
RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT = .4100 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 82
AREA-AVERAGE RUNOFF COEFFICIENT = 0.4093
SUBAREA AREA(ACRES) = 11.15 SUBAREA RUNOFF(CFS) = 10.74 TOTAL AREA(ACRES) = 11.3 TOTAL RUNOFF(CFS) = 10.85 TC(MIN.) = 7.92

**************************************************************************** FLOW PROCESS FROM NODE 5.18 TO NODE 5.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 78.80 DOWNSTREAM(FEET) = 72.60 FLOW LENGTH(FEET) = 90.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 15.0 INCH PIPE IS 8.0 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 16.34
ESTIMATED PIPE DIAMETER(INCH) = 15.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 10.85
PIPE TRAVEL TIME(MIN.) = 0.09 Tc(MIN.) = 8.01

…VMP - Hydrology & Hydraulic Report - Final.docx page 29

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
LONGEST FLOWPATH FROM NODE 5.16 TO NODE 5.20 = 810.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.20 TO NODE 5.20 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 10.85 8.01 2.333 11.28
LONGEST FLOWPATH FROM NODE 5.16 TO NODE 5.20 = 810.00 FEET.

** MEMORY BANK # 1 CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 22.65 14.40 1.598 38.73
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.20 = 2265.00 FEET.

** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 23.45 8.01 2.333
2 30.08 14.40 1.598

COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 30.08 Tc(MIN.) = 14.40
TOTAL AREA(ACRES) = 50.0

**************************************************************************** FLOW PROCESS FROM NODE 5.20 TO NODE 5.20 IS CODE = 12 ---------------------------------------------------------------------------- >>>>>CLEAR MEMORY BANK # 1 <<<<<
============================================================================

**************************************************************************** FLOW PROCESS FROM NODE 5.20 TO NODE 5.20 IS CODE = 10 ---------------------------------------------------------------------------- >>>>>MAIN-STREAM MEMORY COPIED ONTO MEMORY BANK # 1 <<<<< ============================================================================

**************************************************************************** FLOW PROCESS FROM NODE 5.31 TO NODE 5.32 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ GENERAL COMMERCIAL RUNOFF COEFFICIENT = .8200
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 95
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 126.90
DOWNSTREAM ELEVATION(FEET) = 126.10
ELEVATION DIFFERENCE(FEET) = 0.80
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 4.063
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 56.00
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 2 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.162
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.

SUBAREA RUNOFF(CFS) = 0.26
TOTAL AREA(ACRES) = 0.10 TOTAL RUNOFF(CFS) = 0.26

**************************************************************************** FLOW PROCESS FROM NODE 5.32 TO NODE 5.33 IS CODE = 61 ----------------------------------------------------------------------------

…VMP - Hydrology & Hydraulic Report - Final.docx page 30

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
>>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STANDARD CURB SECTION USED)<<<<<
============================================================================ UPSTREAM ELEVATION(FEET) = 126.10 DOWNSTREAM ELEVATION(FEET) = 95.70 STREET LENGTH(FEET) = 1325.00 CURB HEIGHT(INCHES) = 6.0 STREET HALFWIDTH(FEET) = 26.00

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 = 1
STREET PARKWAY CROSSFALL(DECIMAL) = 0.020
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0200

**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 3.26 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.31
HALFSTREET FLOOD WIDTH(FEET) = 9.34
AVERAGE FLOW VELOCITY(FEET/SEC.) = 3.28
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 1.03
STREET FLOW TRAVEL TIME(MIN.) = 6.72 Tc(MIN.) = 10.79 2 YEAR RAINFALL INTENSITY(INCH/HOUR) = 1.926
GENERAL COMMERCIAL RUNOFF COEFFICIENT = .8200
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 95
AREA-AVERAGE RUNOFF COEFFICIENT = 0.820
SUBAREA AREA(ACRES) = 3.65 SUBAREA RUNOFF(CFS) = 5.76 TOTAL AREA(ACRES) = 3.8 PEAK FLOW RATE(CFS) = 5.92

END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.37 HALFSTREET FLOOD WIDTH(FEET) = 12.06 FLOW VELOCITY(FEET/SEC.) = 3.76 DEPTH*VELOCITY(FT*FT/SEC.) = 1.38 LONGEST FLOWPATH FROM NODE 5.31 TO NODE 5.33 = 1425.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.33 TO NODE 5.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 86.00 DOWNSTREAM(FEET) = 72.60 FLOW LENGTH(FEET) = 85.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 9.0 INCH PIPE IS 6.0 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 18.96
ESTIMATED PIPE DIAMETER(INCH) = 9.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 5.92
PIPE TRAVEL TIME(MIN.) = 0.07 Tc(MIN.) = 10.86
LONGEST FLOWPATH FROM NODE 5.31 TO NODE 5.20 = 1510.00 FEET.

** MAIN STREAM CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 5.92 10.86 1.917 3.75
LONGEST FLOWPATH FROM NODE 5.31 TO NODE 5.20 = 1510.00 FEET.

** MEMORY BANK # 1 CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 30.08 14.40 1.598 50.01

…VMP - Hydrology & Hydraulic Report - Final.docx page 31

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.20 = 2265.00 FEET.

** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 28.60 10.86 1.917
2 35.02 14.40 1.598

COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 35.02 Tc(MIN.) = 14.40
TOTAL AREA(ACRES) = 53.8

**************************************************************************** FLOW PROCESS FROM NODE 6.01 TO NODE 6.02 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ LAWNS, GOLF COURSES, ETC. GOOD COVER RUNOFF COEFFICIENT = .3500 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 80
INITIAL SUBAREA FLOW-LENGTH(FEET) = 145.00
UPSTREAM ELEVATION(FEET) = 160.00
DOWNSTREAM ELEVATION(FEET) = 129.50
ELEVATION DIFFERENCE(FEET) = 30.50
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 100.00
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 2 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.733
SUBAREA RUNOFF(CFS) = 0.16
TOTAL AREA(ACRES) = 0.17 TOTAL RUNOFF(CFS) = 0.16

**************************************************************************** FLOW PROCESS FROM NODE 6.02 TO NODE 6.03 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 126.00 DOWNSTREAM(FEET) = 108.30 FLOW LENGTH(FEET) = 415.00 MANNING'S N = 0.011
ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 4.000
DEPTH OF FLOW IN 4.0 INCH PIPE IS 1.7 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 4.77
ESTIMATED PIPE DIAMETER(INCH) = 4.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 0.16
PIPE TRAVEL TIME(MIN.) = 1.45 Tc(MIN.) = 7.72
LONGEST FLOWPATH FROM NODE 6.01 TO NODE 6.03 = 560.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 6.03 TO NODE 6.03 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 2 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.390
RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT = .4100 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 82
AREA-AVERAGE RUNOFF COEFFICIENT = 0.4026
SUBAREA AREA(ACRES) = 1.20 SUBAREA RUNOFF(CFS) = 1.18 TOTAL AREA(ACRES) = 1.4 TOTAL RUNOFF(CFS) = 1.32

…VMP - Hydrology & Hydraulic Report - Final.docx page 32

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
TC(MIN.) = 7.72

**************************************************************************** FLOW PROCESS FROM NODE 6.03 TO NODE 6.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 105.80 DOWNSTREAM(FEET) = 102.50 FLOW LENGTH(FEET) = 35.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 6.0 INCH PIPE IS 3.6 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 10.84
ESTIMATED PIPE DIAMETER(INCH) = 6.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 1.32
PIPE TRAVEL TIME(MIN.) = 0.05 Tc(MIN.) = 7.77
LONGEST FLOWPATH FROM NODE 6.01 TO NODE 6.20 = 595.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 7.01 TO NODE 7.02 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 233.00
DOWNSTREAM ELEVATION(FEET) = 226.00
ELEVATION DIFFERENCE(FEET) = 7.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 7.058
2 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.531
SUBAREA RUNOFF(CFS) = 0.13
TOTAL AREA(ACRES) = 0.15 TOTAL RUNOFF(CFS) = 0.13

**************************************************************************** FLOW PROCESS FROM NODE 7.02 TO NODE 7.20 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 226.00 DOWNSTREAM(FEET) = 111.60 CHANNEL LENGTH THRU SUBAREA(FEET) = 1000.00 CHANNEL SLOPE = 0.1144 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION NOTE: CHANNEL SLOPE OF .1 WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.13
FLOW VELOCITY(FEET/SEC) = 4.74 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 3.51 Tc(MIN.) = 10.57
LONGEST FLOWPATH FROM NODE 7.01 TO NODE 7.20 = 1100.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 7.20 TO NODE 7.20 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 2 YEAR RAINFALL INTENSITY(INCH/HOUR) = 1.951
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 7.02 SUBAREA RUNOFF(CFS) = 4.79 TOTAL AREA(ACRES) = 7.2 TOTAL RUNOFF(CFS) = 4.90 TC(MIN.) = 10.57
============================================================================ ============================================================================

END OF RATIONAL METHOD ANALYSIS

…VMP - Hydrology & Hydraulic Report - Final.docx page 33

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
Existing 25-Year Storm Event Hydrology

____________________________________________________________________________ ****************************************************************************

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 1678

Analysis prepared by:

civTEC
999 Corporate Dr., Suite 100
Ladera Ranch, CA 92694
ph: 949.463.8822

************************** DESCRIPTION OF STUDY ************************** * VETERANS MEMORIAL PARK * * EXISTING CONDITION * * 25-YEAR STORM EVENT * **************************************************************************

FILE NAME: VMP_E25.DAT
TIME/DATE OF STUDY: 16:34 01/22/2023
---------------------------------------------------------------------------- USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION:
---------------------------------------------------------------------------- 2003 SAN DIEGO MANUAL CRITERIA

USER SPECIFIED STORM EVENT(YEAR) = 25.00
6-HOUR DURATION PRECIPITATION (INCHES) = 2.100
SPECIFIED MINIMUM PIPE SIZE(INCH) = 12.00
SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE = 0.95 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 26.0 12.0 0.020/0.020/0.020 0.50 1.50 0.0313 0.167 0.0150

GLOBAL STREET FLOW-DEPTH CONSTRAINTS:

1. Relative Flow-Depth = 1.00 FEET
as (Maximum Allowable Street Flow Depth) - (Top-of-Curb)

2. (Depth)*(Velocity) Constraint = 10.0 (FT*FT/S)
*SIZE PIPE WITH A FLOW CAPACITY GREATER THAN
OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.*

**************************************************************************** FLOW PROCESS FROM NODE 1.10 TO NODE 1.15 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 108.00
DOWNSTREAM ELEVATION(FEET) = 93.00
ELEVATION DIFFERENCE(FEET) = 15.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.783
SUBAREA RUNOFF(CFS) = 0.20

…VMP - Hydrology & Hydraulic Report - Final.docx page 34

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
TOTAL AREA(ACRES) = 0.12 TOTAL RUNOFF(CFS) = 0.20

**************************************************************************** FLOW PROCESS FROM NODE 1.15 TO NODE 1.20 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 93.00 DOWNSTREAM(FEET) = 48.20 CHANNEL LENGTH THRU SUBAREA(FEET) = 525.00 CHANNEL SLOPE = 0.0853 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.20
FLOW VELOCITY(FEET/SEC) = 4.38 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 2.00 Tc(MIN.) = 8.26
LONGEST FLOWPATH FROM NODE 1.10 TO NODE 1.20 = 625.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 1.20 TO NODE 1.20 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.001
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 2.40 SUBAREA RUNOFF(CFS) = 3.36 TOTAL AREA(ACRES) = 2.5 TOTAL RUNOFF(CFS) = 3.53 TC(MIN.) = 8.26

**************************************************************************** FLOW PROCESS FROM NODE 2.10 TO NODE 2.20 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 105.00
UPSTREAM ELEVATION(FEET) = 59.00
DOWNSTREAM ELEVATION(FEET) = 49.30
ELEVATION DIFFERENCE(FEET) = 9.70
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.434
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 100.00
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.702
SUBAREA RUNOFF(CFS) = 0.79
TOTAL AREA(ACRES) = 0.48 TOTAL RUNOFF(CFS) = 0.79

**************************************************************************** FLOW PROCESS FROM NODE 3.10 TO NODE 3.15 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 268.00
DOWNSTREAM ELEVATION(FEET) = 258.00
ELEVATION DIFFERENCE(FEET) = 10.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.783
SUBAREA RUNOFF(CFS) = 0.18

…VMP - Hydrology & Hydraulic Report - Final.docx page 35

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
TOTAL AREA(ACRES) = 0.11 TOTAL RUNOFF(CFS) = 0.18

**************************************************************************** FLOW PROCESS FROM NODE 3.15 TO NODE 3.20 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 258.00 DOWNSTREAM(FEET) = 45.50 CHANNEL LENGTH THRU SUBAREA(FEET) = 2375.00 CHANNEL SLOPE = 0.0895 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.18
FLOW VELOCITY(FEET/SEC) = 4.49 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 8.82 Tc(MIN.) = 15.09
LONGEST FLOWPATH FROM NODE 3.10 TO NODE 3.20 = 2475.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 3.20 TO NODE 3.20 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.714
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 34.37 SUBAREA RUNOFF(CFS) = 32.64 TOTAL AREA(ACRES) = 34.5 TOTAL RUNOFF(CFS) = 32.75 TC(MIN.) = 15.09

**************************************************************************** FLOW PROCESS FROM NODE 4.10 TO NODE 4.15 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 200.00
DOWNSTREAM ELEVATION(FEET) = 186.00
ELEVATION DIFFERENCE(FEET) = 14.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.783
SUBAREA RUNOFF(CFS) = 0.18
TOTAL AREA(ACRES) = 0.11 TOTAL RUNOFF(CFS) = 0.18

**************************************************************************** FLOW PROCESS FROM NODE 4.15 TO NODE 4.20 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 186.00 DOWNSTREAM(FEET) = 94.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 340.00 CHANNEL SLOPE = 0.2706 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION NOTE: CHANNEL SLOPE OF .1 WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.18
FLOW VELOCITY(FEET/SEC) = 4.74 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 1.19 Tc(MIN.) = 7.46
LONGEST FLOWPATH FROM NODE 4.10 TO NODE 4.20 = 440.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 4.20 TO NODE 4.20 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<

…VMP - Hydrology & Hydraulic Report - Final.docx page 36

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
============================================================================ 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.274
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 0.90 SUBAREA RUNOFF(CFS) = 1.35 TOTAL AREA(ACRES) = 1.0 TOTAL RUNOFF(CFS) = 1.51 TC(MIN.) = 7.46

**************************************************************************** FLOW PROCESS FROM NODE 5.10 TO NODE 5.15 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 270.00
DOWNSTREAM ELEVATION(FEET) = 266.00
ELEVATION DIFFERENCE(FEET) = 4.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 8.505
25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.928
SUBAREA RUNOFF(CFS) = 0.74
TOTAL AREA(ACRES) = 0.54 TOTAL RUNOFF(CFS) = 0.74

**************************************************************************** FLOW PROCESS FROM NODE 5.15 TO NODE 5.20 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 266.00 DOWNSTREAM(FEET) = 72.60 CHANNEL LENGTH THRU SUBAREA(FEET) = 1945.00 CHANNEL SLOPE = 0.0994 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.74
FLOW VELOCITY(FEET/SEC) = 4.73 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 6.85 Tc(MIN.) = 15.36
LONGEST FLOWPATH FROM NODE 5.10 TO NODE 5.20 = 2045.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.20 TO NODE 5.20 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.683
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 48.72 SUBAREA RUNOFF(CFS) = 45.75 TOTAL AREA(ACRES) = 49.3 TOTAL RUNOFF(CFS) = 46.26 TC(MIN.) = 15.36

**************************************************************************** FLOW PROCESS FROM NODE 5.30 TO NODE 5.35 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ LIMITED INDUSTRIAL RUNOFF COEFFICIENT = .8500

…VMP - Hydrology & Hydraulic Report - Final.docx page 37

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 96
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 126.90
DOWNSTREAM ELEVATION(FEET) = 126.10
ELEVATION DIFFERENCE(FEET) = 0.80
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 3.627
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 56.00
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.533
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.

SUBAREA RUNOFF(CFS) = 0.47
TOTAL AREA(ACRES) = 0.10 TOTAL RUNOFF(CFS) = 0.47

**************************************************************************** FLOW PROCESS FROM NODE 5.35 TO NODE 5.40 IS CODE = 62 ---------------------------------------------------------------------------- >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 1 USED)<<<<<
============================================================================ UPSTREAM ELEVATION(FEET) = 126.10 DOWNSTREAM ELEVATION(FEET) = 95.70 STREET LENGTH(FEET) = 1325.00 CURB HEIGHT(INCHES) = 6.0 STREET HALFWIDTH(FEET) = 26.00

DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 12.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020

**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 7.55 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.43
HALFSTREET FLOOD WIDTH(FEET) = 13.17
AVERAGE FLOW VELOCITY(FEET/SEC.) = 4.01
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 1.73
STREET FLOW TRAVEL TIME(MIN.) = 5.51 Tc(MIN.) = 9.14 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.750
LIMITED INDUSTRIAL RUNOFF COEFFICIENT = .8500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 96
AREA-AVERAGE RUNOFF COEFFICIENT = 0.850
SUBAREA AREA(ACRES) = 4.30 SUBAREA RUNOFF(CFS) = 13.71 TOTAL AREA(ACRES) = 4.4 PEAK FLOW RATE(CFS) = 14.03

END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.51 HALFSTREET FLOOD WIDTH(FEET) = 17.32 FLOW VELOCITY(FEET/SEC.) = 4.64 DEPTH*VELOCITY(FT*FT/SEC.) = 2.35 *NOTE: INITIAL SUBAREA NOMOGRAPH WITH SUBAREA PARAMETERS, AND L = 1325.0 FT WITH ELEVATION-DROP = 30.4 FT, IS 20.2 CFS, WHICH EXCEEDS THE TOP-OF-CURB STREET CAPACITY AT NODE 5.40 LONGEST FLOWPATH FROM NODE 5.30 TO NODE 5.40 = 1425.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.40 TO NODE 5.50 IS CODE = 41 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING USER-SPECIFIED PIPESIZE (EXISTING ELEMENT)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 86.00 DOWNSTREAM(FEET) = 84.00 FLOW LENGTH(FEET) = 82.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 24.0 INCH PIPE IS 10.7 INCHES

…VMP - Hydrology & Hydraulic Report - Final.docx page 38

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
PIPE-FLOW VELOCITY(FEET/SEC.) = 10.40
GIVEN PIPE DIAMETER(INCH) = 24.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 14.03
PIPE TRAVEL TIME(MIN.) = 0.13 Tc(MIN.) = 9.27
LONGEST FLOWPATH FROM NODE 5.30 TO NODE 5.50 = 1507.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.50 TO NODE 5.40 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 14.03 9.27 3.716 4.40
LONGEST FLOWPATH FROM NODE 5.30 TO NODE 5.40 = 1507.00 FEET.

** MEMORY BANK # 1 CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 46.26 15.36 2.683 49.26
LONGEST FLOWPATH FROM NODE 5.10 TO NODE 5.40 = 2045.00 FEET.

** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 41.94 9.27 3.716
2 56.38 15.36 2.683

COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 56.38 Tc(MIN.) = 15.36
TOTAL AREA(ACRES) = 53.7

**************************************************************************** FLOW PROCESS FROM NODE 6.10 TO NODE 6.15 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 158.00
DOWNSTREAM ELEVATION(FEET) = 148.00
ELEVATION DIFFERENCE(FEET) = 10.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.783
SUBAREA RUNOFF(CFS) = 0.20
TOTAL AREA(ACRES) = 0.12 TOTAL RUNOFF(CFS) = 0.20

**************************************************************************** FLOW PROCESS FROM NODE 6.15 TO NODE 6.20 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 148.00 DOWNSTREAM(FEET) = 108.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 290.00 CHANNEL SLOPE = 0.1379 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION NOTE: CHANNEL SLOPE OF .1 WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.20
FLOW VELOCITY(FEET/SEC) = 4.74 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 1.02 Tc(MIN.) = 7.29
LONGEST FLOWPATH FROM NODE 6.10 TO NODE 6.20 = 390.00 FEET.

…VMP - Hydrology & Hydraulic Report - Final.docx page 39

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
**************************************************************************** FLOW PROCESS FROM NODE 6.20 TO NODE 6.20 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.340
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 1.25 SUBAREA RUNOFF(CFS) = 1.90 TOTAL AREA(ACRES) = 1.4 TOTAL RUNOFF(CFS) = 2.08 TC(MIN.) = 7.29

**************************************************************************** FLOW PROCESS FROM NODE 7.10 TO NODE 7.15 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 233.00
DOWNSTREAM ELEVATION(FEET) = 226.00
ELEVATION DIFFERENCE(FEET) = 7.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 7.058
25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.430
SUBAREA RUNOFF(CFS) = 0.23
TOTAL AREA(ACRES) = 0.15 TOTAL RUNOFF(CFS) = 0.23

**************************************************************************** FLOW PROCESS FROM NODE 7.15 TO NODE 7.20 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 226.00 DOWNSTREAM(FEET) = 111.60 CHANNEL LENGTH THRU SUBAREA(FEET) = 1000.00 CHANNEL SLOPE = 0.1144 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION NOTE: CHANNEL SLOPE OF .1 WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.23
FLOW VELOCITY(FEET/SEC) = 4.74 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 3.51 Tc(MIN.) = 10.57
LONGEST FLOWPATH FROM NODE 7.10 TO NODE 7.20 = 1100.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 7.20 TO NODE 7.20 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.414
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 7.02 SUBAREA RUNOFF(CFS) = 8.39 TOTAL AREA(ACRES) = 7.2 TOTAL RUNOFF(CFS) = 8.57 TC(MIN.) = 10.57
============================================================================ ============================================================================

END OF RATIONAL METHOD ANALYSIS

…VMP - Hydrology & Hydraulic Report - Final.docx page 40

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
Proposed 25-Year Storm Event Hydrology
____________________________________________________________________________ ****************************************************************************

Analysis prepared by:

civTEC
999 Corporate Dr., Suite 100
Ladera Ranch, CA 92694
ph: 949.463.8822

************************** DESCRIPTION OF STUDY ************************** * VETERANS MEMORIAL PARK * * PROPOSED CONDITION * * 25-YEAR STORM EVENT * **************************************************************************

FILE NAME: VMP_P25.DAT
TIME/DATE OF STUDY: 09:43 07/04/2024
---------------------------------------------------------------------------- USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION:
---------------------------------------------------------------------------- 2003 SAN DIEGO MANUAL CRITERIA

USER SPECIFIED STORM EVENT(YEAR) = 25.00
6-HOUR DURATION PRECIPITATION (INCHES) = 2.100
SPECIFIED MINIMUM PIPE SIZE(INCH) = 4.00
SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE = 0.95 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 26.0 10.0 0.020/0.020/0.020 0.50 1.50 0.0312 0.167 0.0150

GLOBAL STREET FLOW-DEPTH CONSTRAINTS:

1. Relative Flow-Depth = 0.00 FEET
as (Maximum Allowable Street Flow Depth) - (Top-of-Curb)

2. (Depth)*(Velocity) Constraint = 6.0 (FT*FT/S)
*SIZE PIPE WITH A FLOW CAPACITY GREATER THAN
OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.*

**************************************************************************** FLOW PROCESS FROM NODE 1.01 TO NODE 1.02 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ LAWNS, GOLF COURSES, ETC. GOOD COVER RUNOFF COEFFICIENT = .3500 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 80
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 91.80
DOWNSTREAM ELEVATION(FEET) = 82.00
ELEVATION DIFFERENCE(FEET) = 9.80
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.309
25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.762
SUBAREA RUNOFF(CFS) = 0.25
TOTAL AREA(ACRES) = 0.15 TOTAL RUNOFF(CFS) = 0.25

…VMP - Hydrology & Hydraulic Report - Final.docx page 41

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
**************************************************************************** FLOW PROCESS FROM NODE 1.02 TO NODE 1.03 IS CODE = 51 ---------------------------------------------------------------------------- >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 82.00 DOWNSTREAM(FEET) = 55.80 CHANNEL LENGTH THRU SUBAREA(FEET) = 265.00 CHANNEL SLOPE = 0.0989 CHANNEL BASE(FEET) = 0.00 "Z" FACTOR = 1.000
MANNING'S FACTOR = 0.015 MAXIMUM DEPTH(FEET) = 1.00 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.521
RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT = .4100 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 82
TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 1.33 TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 8.35 AVERAGE FLOW DEPTH(FEET) = 0.40 TRAVEL TIME(MIN.) = 0.53 Tc(MIN.) = 6.84
SUBAREA AREA(ACRES) = 1.17 SUBAREA RUNOFF(CFS) = 2.17 AREA-AVERAGE RUNOFF COEFFICIENT = 0.403
TOTAL AREA(ACRES) = 1.3 PEAK FLOW RATE(CFS) = 2.41

END OF SUBAREA CHANNEL FLOW HYDRAULICS:

DEPTH(FEET) = 0.50 FLOW VELOCITY(FEET/SEC.) = 9.67 LONGEST FLOWPATH FROM NODE 1.01 TO NODE 1.03 = 365.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 1.03 TO NODE 1.04 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 54.70 DOWNSTREAM(FEET) = 54.30 FLOW LENGTH(FEET) = 20.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 9.0 INCH PIPE IS 6.6 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 6.89
ESTIMATED PIPE DIAMETER(INCH) = 9.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 2.41
PIPE TRAVEL TIME(MIN.) = 0.05 Tc(MIN.) = 6.89
LONGEST FLOWPATH FROM NODE 1.01 TO NODE 1.04 = 385.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 1.04 TO NODE 1.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 51.75 DOWNSTREAM(FEET) = 48.20 FLOW LENGTH(FEET) = 95.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 9.0 INCH PIPE IS 5.3 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 8.88
ESTIMATED PIPE DIAMETER(INCH) = 9.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 2.41
PIPE TRAVEL TIME(MIN.) = 0.18 Tc(MIN.) = 7.06
LONGEST FLOWPATH FROM NODE 1.01 TO NODE 1.20 = 480.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 2.01 TO NODE 2.02 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ STREETS & ROADS (CURBS/STORM DRAINS) RUNOFF COEFFICIENT = .8700 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 98
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 68.30
DOWNSTREAM ELEVATION(FEET) = 65.70

…VMP - Hydrology & Hydraulic Report - Final.docx page 42

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
ELEVATION DIFFERENCE(FEET) = 2.60
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 2.625
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 76.00
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.533
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.

SUBAREA RUNOFF(CFS) = 0.24
TOTAL AREA(ACRES) = 0.05 TOTAL RUNOFF(CFS) = 0.24

**************************************************************************** FLOW PROCESS FROM NODE 2.02 TO NODE 2.03 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 62.50 DOWNSTREAM(FEET) = 54.30 FLOW LENGTH(FEET) = 80.00 MANNING'S N = 0.011
ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 4.000
DEPTH OF FLOW IN 4.0 INCH PIPE IS 1.6 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 7.26
ESTIMATED PIPE DIAMETER(INCH) = 4.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 0.24
PIPE TRAVEL TIME(MIN.) = 0.18 Tc(MIN.) = 2.81
LONGEST FLOWPATH FROM NODE 2.01 TO NODE 2.03 = 180.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 2.03 TO NODE 2.03 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.533
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.

RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT = .4100 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 82
AREA-AVERAGE RUNOFF COEFFICIENT = 0.4661
SUBAREA AREA(ACRES) = 0.36 SUBAREA RUNOFF(CFS) = 0.82 TOTAL AREA(ACRES) = 0.4 TOTAL RUNOFF(CFS) = 1.06 TC(MIN.) = 2.81

OFFICE PROFESSIONAL/COMMERCIAL RUNOFF COEFFICIENT = .8500 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 96
AREA-AVERAGE RUNOFF COEFFICIENT = 0.6580
SUBAREA AREA(ACRES) = 0.41 SUBAREA RUNOFF(CFS) = 1.93 TOTAL AREA(ACRES) = 0.8 TOTAL RUNOFF(CFS) = 2.99 TC(MIN.) = 2.81

**************************************************************************** FLOW PROCESS FROM NODE 2.03 TO NODE 2.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 51.75 DOWNSTREAM(FEET) = 49.30 FLOW LENGTH(FEET) = 60.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 9.0 INCH PIPE IS 6.0 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 9.63

…VMP - Hydrology & Hydraulic Report - Final.docx page 43

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
ESTIMATED PIPE DIAMETER(INCH) = 9.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 2.99
PIPE TRAVEL TIME(MIN.) = 0.10 Tc(MIN.) = 2.91
LONGEST FLOWPATH FROM NODE 2.01 TO NODE 2.20 = 240.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 3.01 TO NODE 3.02 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 268.00
DOWNSTREAM ELEVATION(FEET) = 258.00
ELEVATION DIFFERENCE(FEET) = 10.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.783
SUBAREA RUNOFF(CFS) = 0.18
TOTAL AREA(ACRES) = 0.11 TOTAL RUNOFF(CFS) = 0.18

**************************************************************************** FLOW PROCESS FROM NODE 3.02 TO NODE 3.03 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 258.00 DOWNSTREAM(FEET) = 87.50 CHANNEL LENGTH THRU SUBAREA(FEET) = 1815.00 CHANNEL SLOPE = 0.0939 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.18
FLOW VELOCITY(FEET/SEC) = 4.60 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 6.58 Tc(MIN.) = 12.85
LONGEST FLOWPATH FROM NODE 3.01 TO NODE 3.03 = 1915.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 3.03 TO NODE 3.03 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.010
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 18.00 SUBAREA RUNOFF(CFS) = 18.97 TOTAL AREA(ACRES) = 18.1 TOTAL RUNOFF(CFS) = 19.08 TC(MIN.) = 12.85

**************************************************************************** FLOW PROCESS FROM NODE 3.03 TO NODE 3.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 82.50 DOWNSTREAM(FEET) = 45.50 FLOW LENGTH(FEET) = 715.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 18.0 INCH PIPE IS 11.0 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 16.82
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 19.08
PIPE TRAVEL TIME(MIN.) = 0.71 Tc(MIN.) = 13.55
LONGEST FLOWPATH FROM NODE 3.01 TO NODE 3.20 = 2630.00 FEET.

****************************************************************************

…VMP - Hydrology & Hydraulic Report - Final.docx page 44

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
FLOW PROCESS FROM NODE 3.20 TO NODE 3.20 IS CODE = 10 ---------------------------------------------------------------------------- >>>>>MAIN-STREAM MEMORY COPIED ONTO MEMORY BANK # 1 <<<<< ============================================================================

**************************************************************************** FLOW PROCESS FROM NODE 3.04 TO NODE 3.05 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ LAWNS, GOLF COURSES, ETC. GOOD COVER RUNOFF COEFFICIENT = .3500 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 80
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 216.90
DOWNSTREAM ELEVATION(FEET) = 206.00
ELEVATION DIFFERENCE(FEET) = 10.90
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.783
SUBAREA RUNOFF(CFS) = 0.40
TOTAL AREA(ACRES) = 0.24 TOTAL RUNOFF(CFS) = 0.40

**************************************************************************** FLOW PROCESS FROM NODE 3.05 TO NODE 3.06 IS CODE = 51 ---------------------------------------------------------------------------- >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 206.00 DOWNSTREAM(FEET) = 190.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 175.00 CHANNEL SLOPE = 0.0914 CHANNEL BASE(FEET) = 0.00 "Z" FACTOR = 1.000
MANNING'S FACTOR = 0.015 MAXIMUM DEPTH(FEET) = 1.00 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.587
LAWNS, GOLF COURSES, ETC. GOOD COVER RUNOFF COEFFICIENT = .3500 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 80
TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 0.67 TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 6.94 AVERAGE FLOW DEPTH(FEET) = 0.31 TRAVEL TIME(MIN.) = 0.42 Tc(MIN.) = 6.69
SUBAREA AREA(ACRES) = 0.33 SUBAREA RUNOFF(CFS) = 0.53 AREA-AVERAGE RUNOFF COEFFICIENT = 0.350
TOTAL AREA(ACRES) = 0.6 PEAK FLOW RATE(CFS) = 0.92

END OF SUBAREA CHANNEL FLOW HYDRAULICS:

DEPTH(FEET) = 0.35 FLOW VELOCITY(FEET/SEC.) = 7.55 LONGEST FLOWPATH FROM NODE 3.04 TO NODE 3.06 = 275.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 3.06 TO NODE 3.07 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 187.00 DOWNSTREAM(FEET) = 54.80 FLOW LENGTH(FEET) = 1085.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 6.0 INCH PIPE IS 2.7 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 10.85
ESTIMATED PIPE DIAMETER(INCH) = 6.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 0.92
PIPE TRAVEL TIME(MIN.) = 1.67 Tc(MIN.) = 8.35
LONGEST FLOWPATH FROM NODE 3.04 TO NODE 3.07 = 1360.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 3.07 TO NODE 3.07 IS CODE = 81 ----------------------------------------------------------------------------

…VMP - Hydrology & Hydraulic Report - Final.docx page 45

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
>>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.974
RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT = .4100 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 82
AREA-AVERAGE RUNOFF COEFFICIENT = 0.4082
SUBAREA AREA(ACRES) = 17.98 SUBAREA RUNOFF(CFS) = 29.29 TOTAL AREA(ACRES) = 18.5 TOTAL RUNOFF(CFS) = 30.09 TC(MIN.) = 8.35

**************************************************************************** FLOW PROCESS FROM NODE 3.07 TO NODE 3.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 52.25 DOWNSTREAM(FEET) = 45.50 FLOW LENGTH(FEET) = 75.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 18.0 INCH PIPE IS 12.5 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 22.96
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 30.09
PIPE TRAVEL TIME(MIN.) = 0.05 Tc(MIN.) = 8.41
LONGEST FLOWPATH FROM NODE 3.04 TO NODE 3.20 = 1435.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 3.20 TO NODE 3.20 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 30.09 8.41 3.957 18.55
LONGEST FLOWPATH FROM NODE 3.04 TO NODE 3.20 = 1435.00 FEET.

** MEMORY BANK # 1 CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 19.08 13.55 2.908 18.11
LONGEST FLOWPATH FROM NODE 3.01 TO NODE 3.20 = 2630.00 FEET.

** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 41.92 8.41 3.957
2 41.19 13.55 2.908

COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 41.92 Tc(MIN.) = 8.41
TOTAL AREA(ACRES) = 36.7

**************************************************************************** FLOW PROCESS FROM NODE 3.20 TO NODE 3.20 IS CODE = 12 ---------------------------------------------------------------------------- >>>>>CLEAR MEMORY BANK # 1 <<<<<
============================================================================

**************************************************************************** FLOW PROCESS FROM NODE 4.01 TO NODE 4.02 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"

…VMP - Hydrology & Hydraulic Report - Final.docx page 46

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 204.00
DOWNSTREAM ELEVATION(FEET) = 178.00
ELEVATION DIFFERENCE(FEET) = 26.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.783
SUBAREA RUNOFF(CFS) = 0.18
TOTAL AREA(ACRES) = 0.11 TOTAL RUNOFF(CFS) = 0.18

**************************************************************************** FLOW PROCESS FROM NODE 4.02 TO NODE 4.03 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 178.00 DOWNSTREAM(FEET) = 113.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 275.00 CHANNEL SLOPE = 0.2364 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION NOTE: CHANNEL SLOPE OF .1 WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.18
FLOW VELOCITY(FEET/SEC) = 4.74 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 0.97 Tc(MIN.) = 7.23
LONGEST FLOWPATH FROM NODE 4.01 TO NODE 4.03 = 375.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 4.03 TO NODE 4.03 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.361
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 0.84 SUBAREA RUNOFF(CFS) = 1.28 TOTAL AREA(ACRES) = 0.9 TOTAL RUNOFF(CFS) = 1.45 TC(MIN.) = 7.23

**************************************************************************** FLOW PROCESS FROM NODE 4.03 TO NODE 4.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 105.30 DOWNSTREAM(FEET) = 94.00 FLOW LENGTH(FEET) = 55.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 6.0 INCH PIPE IS 3.0 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 14.87
ESTIMATED PIPE DIAMETER(INCH) = 6.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 1.45
PIPE TRAVEL TIME(MIN.) = 0.06 Tc(MIN.) = 7.29
LONGEST FLOWPATH FROM NODE 4.01 TO NODE 4.20 = 430.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.01 TO NODE 5.02 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 270.00
DOWNSTREAM ELEVATION(FEET) = 266.00
ELEVATION DIFFERENCE(FEET) = 4.00

…VMP - Hydrology & Hydraulic Report - Final.docx page 47

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 8.505
25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.928
SUBAREA RUNOFF(CFS) = 0.74
TOTAL AREA(ACRES) = 0.54 TOTAL RUNOFF(CFS) = 0.74

**************************************************************************** FLOW PROCESS FROM NODE 5.02 TO NODE 5.03 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 266.00 DOWNSTREAM(FEET) = 110.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 1420.00 CHANNEL SLOPE = 0.1096 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION NOTE: CHANNEL SLOPE OF .1 WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.74
FLOW VELOCITY(FEET/SEC) = 4.74 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 4.99 Tc(MIN.) = 13.49
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.03 = 1520.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.03 TO NODE 5.03 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.916
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 16.97 SUBAREA RUNOFF(CFS) = 17.32 TOTAL AREA(ACRES) = 17.5 TOTAL RUNOFF(CFS) = 17.87 TC(MIN.) = 13.49

**************************************************************************** FLOW PROCESS FROM NODE 5.03 TO NODE 5.04 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 106.80 DOWNSTREAM(FEET) = 105.30 FLOW LENGTH(FEET) = 105.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 21.0 INCH PIPE IS 14.5 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 10.12
ESTIMATED PIPE DIAMETER(INCH) = 21.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 17.87
PIPE TRAVEL TIME(MIN.) = 0.17 Tc(MIN.) = 13.67
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.04 = 1625.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.04 TO NODE 5.04 IS CODE = 10 ---------------------------------------------------------------------------- >>>>>MAIN-STREAM MEMORY COPIED ONTO MEMORY BANK # 1 <<<<< ============================================================================

**************************************************************************** FLOW PROCESS FROM NODE 5.05 TO NODE 5.06 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 270.00
DOWNSTREAM ELEVATION(FEET) = 266.00
ELEVATION DIFFERENCE(FEET) = 4.00

…VMP - Hydrology & Hydraulic Report - Final.docx page 48

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 8.505
25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.928
SUBAREA RUNOFF(CFS) = 0.41
TOTAL AREA(ACRES) = 0.30 TOTAL RUNOFF(CFS) = 0.41

**************************************************************************** FLOW PROCESS FROM NODE 5.06 TO NODE 5.07 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 266.00 DOWNSTREAM(FEET) = 123.80 CHANNEL LENGTH THRU SUBAREA(FEET) = 1310.00 CHANNEL SLOPE = 0.1078 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION NOTE: CHANNEL SLOPE OF .1 WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.41
FLOW VELOCITY(FEET/SEC) = 4.74 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 4.60 Tc(MIN.) = 13.11
LONGEST FLOWPATH FROM NODE 5.05 TO NODE 5.07 = 1410.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.07 TO NODE 5.07 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.972
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 12.45 SUBAREA RUNOFF(CFS) = 12.95 TOTAL AREA(ACRES) = 12.8 TOTAL RUNOFF(CFS) = 13.26 TC(MIN.) = 13.11

**************************************************************************** FLOW PROCESS FROM NODE 5.07 TO NODE 5.04 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 117.30 DOWNSTREAM(FEET) = 105.30 FLOW LENGTH(FEET) = 150.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 15.0 INCH PIPE IS 8.6 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 18.13
ESTIMATED PIPE DIAMETER(INCH) = 15.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 13.26
PIPE TRAVEL TIME(MIN.) = 0.14 Tc(MIN.) = 13.25
LONGEST FLOWPATH FROM NODE 5.05 TO NODE 5.04 = 1560.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.04 TO NODE 5.04 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 13.26 13.25 2.952 12.75
LONGEST FLOWPATH FROM NODE 5.05 TO NODE 5.04 = 1560.00 FEET.

** MEMORY BANK # 1 CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 17.87 13.67 2.893 17.51
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.04 = 1625.00 FEET.

…VMP - Hydrology & Hydraulic Report - Final.docx page 49

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 30.58 13.25 2.952
2 30.87 13.67 2.893

COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 30.87 Tc(MIN.) = 13.67
TOTAL AREA(ACRES) = 30.3

**************************************************************************** FLOW PROCESS FROM NODE 5.04 TO NODE 5.04 IS CODE = 12 ---------------------------------------------------------------------------- >>>>>CLEAR MEMORY BANK # 1 <<<<<
============================================================================

**************************************************************************** FLOW PROCESS FROM NODE 5.04 TO NODE 5.08 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 105.10 DOWNSTREAM(FEET) = 89.90 FLOW LENGTH(FEET) = 490.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 21.0 INCH PIPE IS 16.5 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 15.22
ESTIMATED PIPE DIAMETER(INCH) = 21.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 30.87
PIPE TRAVEL TIME(MIN.) = 0.54 Tc(MIN.) = 14.20
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.08 = 2115.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.08 TO NODE 5.08 IS CODE = 10 ---------------------------------------------------------------------------- >>>>>MAIN-STREAM MEMORY COPIED ONTO MEMORY BANK # 1 <<<<< ============================================================================

**************************************************************************** FLOW PROCESS FROM NODE 5.09 TO NODE 5.10 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ LAWNS, GOLF COURSES, ETC. GOOD COVER RUNOFF COEFFICIENT = .3500 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 80
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 247.40
DOWNSTREAM ELEVATION(FEET) = 218.00
ELEVATION DIFFERENCE(FEET) = 29.40
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.783
SUBAREA RUNOFF(CFS) = 0.27
TOTAL AREA(ACRES) = 0.16 TOTAL RUNOFF(CFS) = 0.27

**************************************************************************** FLOW PROCESS FROM NODE 5.10 TO NODE 5.11 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 218.00 DOWNSTREAM(FEET) = 103.50 CHANNEL LENGTH THRU SUBAREA(FEET) = 780.00 CHANNEL SLOPE = 0.1468 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION NOTE: CHANNEL SLOPE OF .1 WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.27
FLOW VELOCITY(FEET/SEC) = 4.74 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL)

…VMP - Hydrology & Hydraulic Report - Final.docx page 50

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
TRAVEL TIME(MIN.) = 2.74 Tc(MIN.) = 9.01
LONGEST FLOWPATH FROM NODE 5.09 TO NODE 5.11 = 880.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.11 TO NODE 5.11 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.785
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 7.77 SUBAREA RUNOFF(CFS) = 10.29 TOTAL AREA(ACRES) = 7.9 TOTAL RUNOFF(CFS) = 10.51 TC(MIN.) = 9.01

**************************************************************************** FLOW PROCESS FROM NODE 5.11 TO NODE 5.12 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 99.00 DOWNSTREAM(FEET) = 98.00 FLOW LENGTH(FEET) = 70.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 18.0 INCH PIPE IS 11.4 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 8.92
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 10.51
PIPE TRAVEL TIME(MIN.) = 0.13 Tc(MIN.) = 9.14
LONGEST FLOWPATH FROM NODE 5.09 TO NODE 5.12 = 950.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.12 TO NODE 5.12 IS CODE = 10 ---------------------------------------------------------------------------- >>>>>MAIN-STREAM MEMORY COPIED ONTO MEMORY BANK # 2 <<<<< ============================================================================

**************************************************************************** FLOW PROCESS FROM NODE 5.13 TO NODE 5.14 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 173.00
DOWNSTREAM ELEVATION(FEET) = 153.00
ELEVATION DIFFERENCE(FEET) = 20.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.783
SUBAREA RUNOFF(CFS) = 0.20
TOTAL AREA(ACRES) = 0.12 TOTAL RUNOFF(CFS) = 0.20

**************************************************************************** FLOW PROCESS FROM NODE 5.14 TO NODE 5.15 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 153.00 DOWNSTREAM(FEET) = 108.50 CHANNEL LENGTH THRU SUBAREA(FEET) = 235.00 CHANNEL SLOPE = 0.1894 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION NOTE: CHANNEL SLOPE OF .1 WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.20

…VMP - Hydrology & Hydraulic Report - Final.docx page 51

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
FLOW VELOCITY(FEET/SEC) = 4.74 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 0.83 Tc(MIN.) = 7.09
LONGEST FLOWPATH FROM NODE 5.13 TO NODE 5.15 = 335.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.15 TO NODE 5.15 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.416
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 0.42 SUBAREA RUNOFF(CFS) = 0.65 TOTAL AREA(ACRES) = 0.5 TOTAL RUNOFF(CFS) = 0.83 TC(MIN.) = 7.09

**************************************************************************** FLOW PROCESS FROM NODE 5.15 TO NODE 5.12 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 103.00 DOWNSTREAM(FEET) = 98.00 FLOW LENGTH(FEET) = 135.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 6.0 INCH PIPE IS 3.6 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 6.81
ESTIMATED PIPE DIAMETER(INCH) = 6.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 0.83
PIPE TRAVEL TIME(MIN.) = 0.33 Tc(MIN.) = 7.42
LONGEST FLOWPATH FROM NODE 5.13 TO NODE 5.12 = 470.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.12 TO NODE 5.12 IS CODE = 11 ---------------------------------------------------------------------------- >>>>>CONFLUENCE MEMORY BANK # 2 WITH THE MAIN-STREAM MEMORY<<<<< ============================================================================

** MAIN STREAM CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 0.83 7.42 4.288 0.54
LONGEST FLOWPATH FROM NODE 5.13 TO NODE 5.12 = 470.00 FEET.

** MEMORY BANK # 2 CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 10.51 9.14 3.750 7.93
LONGEST FLOWPATH FROM NODE 5.09 TO NODE 5.12 = 950.00 FEET.

** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 9.37 7.42 4.288
2 11.24 9.14 3.750

COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 11.24 Tc(MIN.) = 9.14
TOTAL AREA(ACRES) = 8.5

**************************************************************************** FLOW PROCESS FROM NODE 5.12 TO NODE 5.12 IS CODE = 12 ---------------------------------------------------------------------------- >>>>>CLEAR MEMORY BANK # 2 <<<<<
============================================================================

…VMP - Hydrology & Hydraulic Report - Final.docx page 52

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
**************************************************************************** FLOW PROCESS FROM NODE 5.12 TO NODE 5.08 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 98.00 DOWNSTREAM(FEET) = 89.90 FLOW LENGTH(FEET) = 325.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 15.0 INCH PIPE IS 11.7 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 10.90
ESTIMATED PIPE DIAMETER(INCH) = 15.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 11.24
PIPE TRAVEL TIME(MIN.) = 0.50 Tc(MIN.) = 9.64
LONGEST FLOWPATH FROM NODE 5.09 TO NODE 5.08 = 1275.00 FEET.

** MAIN STREAM CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 11.24 9.64 3.624 8.47
LONGEST FLOWPATH FROM NODE 5.09 TO NODE 5.08 = 1275.00 FEET.

** MEMORY BANK # 1 CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 30.87 14.20 2.822 30.26
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.08 = 2115.00 FEET.

** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 32.18 9.64 3.624
2 39.62 14.20 2.822

COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 39.62 Tc(MIN.) = 14.20
TOTAL AREA(ACRES) = 38.7

**************************************************************************** FLOW PROCESS FROM NODE 5.08 TO NODE 5.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 90.00 DOWNSTREAM(FEET) = 72.60 FLOW LENGTH(FEET) = 150.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 18.0 INCH PIPE IS 14.2 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 26.56
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 39.62
PIPE TRAVEL TIME(MIN.) = 0.09 Tc(MIN.) = 14.30
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.20 = 2265.00 FEET.

…VMP - Hydrology & Hydraulic Report - Final.docx page 53

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
>>>>>MAIN-STREAM MEMORY COPIED ONTO MEMORY BANK # 1 <<<<< ============================================================================

**************************************************************************** FLOW PROCESS FROM NODE 5.16 TO NODE 5.17 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ LAWNS, GOLF COURSES, ETC. GOOD COVER RUNOFF COEFFICIENT = .3500 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 80
INITIAL SUBAREA FLOW-LENGTH(FEET) = 170.00
UPSTREAM ELEVATION(FEET) = 155.00
DOWNSTREAM ELEVATION(FEET) = 129.50
ELEVATION DIFFERENCE(FEET) = 25.50
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 100.00
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.783
SUBAREA RUNOFF(CFS) = 0.22
TOTAL AREA(ACRES) = 0.13 TOTAL RUNOFF(CFS) = 0.22

**************************************************************************** FLOW PROCESS FROM NODE 5.17 TO NODE 5.18 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 126.50 DOWNSTREAM(FEET) = 81.30 FLOW LENGTH(FEET) = 550.00 MANNING'S N = 0.011
ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 4.000
DEPTH OF FLOW IN 4.0 INCH PIPE IS 1.6 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 6.56
ESTIMATED PIPE DIAMETER(INCH) = 4.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 0.22
PIPE TRAVEL TIME(MIN.) = 1.40 Tc(MIN.) = 7.66
LONGEST FLOWPATH FROM NODE 5.16 TO NODE 5.18 = 720.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.18 TO NODE 5.18 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.201
RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT = .4100 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 82
AREA-AVERAGE RUNOFF COEFFICIENT = 0.4093
SUBAREA AREA(ACRES) = 11.15 SUBAREA RUNOFF(CFS) = 19.20 TOTAL AREA(ACRES) = 11.3 TOTAL RUNOFF(CFS) = 19.40 TC(MIN.) = 7.66

**************************************************************************** FLOW PROCESS FROM NODE 5.18 TO NODE 5.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 78.80 DOWNSTREAM(FEET) = 72.60 FLOW LENGTH(FEET) = 90.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 15.0 INCH PIPE IS 12.2 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 18.14
ESTIMATED PIPE DIAMETER(INCH) = 15.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 19.40
PIPE TRAVEL TIME(MIN.) = 0.08 Tc(MIN.) = 7.75

…VMP - Hydrology & Hydraulic Report - Final.docx page 54

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
LONGEST FLOWPATH FROM NODE 5.16 TO NODE 5.20 = 810.00 FEET.

** MAIN STREAM CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 19.40 7.75 4.172 11.28
LONGEST FLOWPATH FROM NODE 5.16 TO NODE 5.20 = 810.00 FEET.

** MEMORY BANK # 1 CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 39.62 14.30 2.810 38.73
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.20 = 2265.00 FEET.

** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 40.86 7.75 4.172
2 52.68 14.30 2.810

COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 52.68 Tc(MIN.) = 14.30
TOTAL AREA(ACRES) = 50.0

**************************************************************************** FLOW PROCESS FROM NODE 5.31 TO NODE 5.32 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ GENERAL COMMERCIAL RUNOFF COEFFICIENT = .8200
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 95
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 126.90
DOWNSTREAM ELEVATION(FEET) = 126.10
ELEVATION DIFFERENCE(FEET) = 0.80
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 4.063
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 56.00
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.533
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.

SUBAREA RUNOFF(CFS) = 0.45
TOTAL AREA(ACRES) = 0.10 TOTAL RUNOFF(CFS) = 0.45

…VMP - Hydrology & Hydraulic Report - Final.docx page 55

DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 10.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020

**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 5.97 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.37
HALFSTREET FLOOD WIDTH(FEET) = 12.06
AVERAGE FLOW VELOCITY(FEET/SEC.) = 3.79
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 1.39
STREET FLOW TRAVEL TIME(MIN.) = 5.82 Tc(MIN.) = 9.88 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.565
GENERAL COMMERCIAL RUNOFF COEFFICIENT = .8200
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 95
AREA-AVERAGE RUNOFF COEFFICIENT = 0.820
SUBAREA AREA(ACRES) = 3.65 SUBAREA RUNOFF(CFS) = 10.67 TOTAL AREA(ACRES) = 3.8 PEAK FLOW RATE(CFS) = 10.96

END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.44 HALFSTREET FLOOD WIDTH(FEET) = 15.46 FLOW VELOCITY(FEET/SEC.) = 4.37 DEPTH*VELOCITY(FT*FT/SEC.) = 1.90 LONGEST FLOWPATH FROM NODE 5.31 TO NODE 5.33 = 1425.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.33 TO NODE 5.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 86.00 DOWNSTREAM(FEET) = 72.60 FLOW LENGTH(FEET) = 85.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 12.0 INCH PIPE IS 7.2 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 22.25
ESTIMATED PIPE DIAMETER(INCH) = 12.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 10.96
PIPE TRAVEL TIME(MIN.) = 0.06 Tc(MIN.) = 9.95
LONGEST FLOWPATH FROM NODE 5.31 TO NODE 5.20 = 1510.00 FEET.

** MAIN STREAM CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 10.96 9.95 3.550 3.75
LONGEST FLOWPATH FROM NODE 5.31 TO NODE 5.20 = 1510.00 FEET.

** MEMORY BANK # 1 CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 52.68 14.30 2.810 50.01

…VMP - Hydrology & Hydraulic Report - Final.docx page 56

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.20 = 2265.00 FEET.

** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 47.62 9.95 3.550
2 61.35 14.30 2.810

COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 61.35 Tc(MIN.) = 14.30
TOTAL AREA(ACRES) = 53.8

**************************************************************************** FLOW PROCESS FROM NODE 6.01 TO NODE 6.02 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ LAWNS, GOLF COURSES, ETC. GOOD COVER RUNOFF COEFFICIENT = .3500 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 80
INITIAL SUBAREA FLOW-LENGTH(FEET) = 145.00
UPSTREAM ELEVATION(FEET) = 160.00
DOWNSTREAM ELEVATION(FEET) = 129.50
ELEVATION DIFFERENCE(FEET) = 30.50
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 100.00
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.783
SUBAREA RUNOFF(CFS) = 0.28
TOTAL AREA(ACRES) = 0.17 TOTAL RUNOFF(CFS) = 0.28

**************************************************************************** FLOW PROCESS FROM NODE 6.02 TO NODE 6.03 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 126.00 DOWNSTREAM(FEET) = 108.30 FLOW LENGTH(FEET) = 415.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 6.0 INCH PIPE IS 1.9 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 5.44
ESTIMATED PIPE DIAMETER(INCH) = 6.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 0.28
PIPE TRAVEL TIME(MIN.) = 1.27 Tc(MIN.) = 7.54
LONGEST FLOWPATH FROM NODE 6.01 TO NODE 6.03 = 560.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 6.03 TO NODE 6.03 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.246
RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT = .4100 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 82
AREA-AVERAGE RUNOFF COEFFICIENT = 0.4026
SUBAREA AREA(ACRES) = 1.20 SUBAREA RUNOFF(CFS) = 2.09 TOTAL AREA(ACRES) = 1.4 TOTAL RUNOFF(CFS) = 2.34 TC(MIN.) = 7.54

…VMP - Hydrology & Hydraulic Report - Final.docx page 57

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS

**************************************************************************** FLOW PROCESS FROM NODE 6.03 TO NODE 6.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 105.80 DOWNSTREAM(FEET) = 102.50 FLOW LENGTH(FEET) = 35.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 9.0 INCH PIPE IS 4.0 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 12.51
ESTIMATED PIPE DIAMETER(INCH) = 9.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 2.34
PIPE TRAVEL TIME(MIN.) = 0.05 Tc(MIN.) = 7.58
LONGEST FLOWPATH FROM NODE 6.01 TO NODE 6.20 = 595.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 7.01 TO NODE 7.02 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 233.00
DOWNSTREAM ELEVATION(FEET) = 226.00
ELEVATION DIFFERENCE(FEET) = 7.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 7.058
25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.430
SUBAREA RUNOFF(CFS) = 0.23
TOTAL AREA(ACRES) = 0.15 TOTAL RUNOFF(CFS) = 0.23

**************************************************************************** FLOW PROCESS FROM NODE 7.02 TO NODE 7.20 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 226.00 DOWNSTREAM(FEET) = 111.60 CHANNEL LENGTH THRU SUBAREA(FEET) = 1000.00 CHANNEL SLOPE = 0.1144 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION NOTE: CHANNEL SLOPE OF .1 WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.23
FLOW VELOCITY(FEET/SEC) = 4.74 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 3.51 Tc(MIN.) = 10.57
LONGEST FLOWPATH FROM NODE 7.01 TO NODE 7.20 = 1100.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 7.20 TO NODE 7.20 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 25 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.414
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 7.02 SUBAREA RUNOFF(CFS) = 8.39 TOTAL AREA(ACRES) = 7.2 TOTAL RUNOFF(CFS) = 8.57 TC(MIN.) = 10.57
============================================================================ ============================================================================

END OF RATIONAL METHOD ANALYSIS

…VMP - Hydrology & Hydraulic Report - Final.docx page 58

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
Existing 50-Year Storm Event Hydrology
____________________________________________________________________________ ****************************************************************************

Analysis prepared by:

civTEC
999 Corporate Dr., Suite 100
Ladera Ranch, CA 92694
ph: 949.463.8822

************************** DESCRIPTION OF STUDY ************************** * VETERANS MEMORIAL PARK * * EXISTING CONDITION * * 50-YEAR STORM EVENT * **************************************************************************

FILE NAME: VMP_E50.DAT
TIME/DATE OF STUDY: 16:37 01/22/2023
---------------------------------------------------------------------------- USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION:
---------------------------------------------------------------------------- 2003 SAN DIEGO MANUAL CRITERIA

USER SPECIFIED STORM EVENT(YEAR) = 50.00
6-HOUR DURATION PRECIPITATION (INCHES) = 2.300
SPECIFIED MINIMUM PIPE SIZE(INCH) = 12.00
SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE = 0.95 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

GLOBAL STREET FLOW-DEPTH CONSTRAINTS:

1. Relative Flow-Depth = 1.00 FEET
as (Maximum Allowable Street Flow Depth) - (Top-of-Curb)

2. (Depth)*(Velocity) Constraint = 10.0 (FT*FT/S)
*SIZE PIPE WITH A FLOW CAPACITY GREATER THAN
OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.*

**************************************************************************** FLOW PROCESS FROM NODE 1.10 TO NODE 1.15 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 108.00
DOWNSTREAM ELEVATION(FEET) = 93.00
ELEVATION DIFFERENCE(FEET) = 15.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.239
SUBAREA RUNOFF(CFS) = 0.22
TOTAL AREA(ACRES) = 0.12 TOTAL RUNOFF(CFS) = 0.22

…VMP - Hydrology & Hydraulic Report - Final.docx page 59

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS

**************************************************************************** FLOW PROCESS FROM NODE 1.15 TO NODE 1.20 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 93.00 DOWNSTREAM(FEET) = 48.20 CHANNEL LENGTH THRU SUBAREA(FEET) = 525.00 CHANNEL SLOPE = 0.0853 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.22
FLOW VELOCITY(FEET/SEC) = 4.38 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 2.00 Tc(MIN.) = 8.26
LONGEST FLOWPATH FROM NODE 1.10 TO NODE 1.20 = 625.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 1.20 TO NODE 1.20 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.383
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 2.40 SUBAREA RUNOFF(CFS) = 3.68 TOTAL AREA(ACRES) = 2.5 TOTAL RUNOFF(CFS) = 3.87 TC(MIN.) = 8.26

**************************************************************************** FLOW PROCESS FROM NODE 2.10 TO NODE 2.20 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 105.00
UPSTREAM ELEVATION(FEET) = 59.00
DOWNSTREAM ELEVATION(FEET) = 49.30
ELEVATION DIFFERENCE(FEET) = 9.70
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.434
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 100.00
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.150
SUBAREA RUNOFF(CFS) = 0.87
TOTAL AREA(ACRES) = 0.48 TOTAL RUNOFF(CFS) = 0.87

**************************************************************************** FLOW PROCESS FROM NODE 3.10 TO NODE 3.15 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 268.00
DOWNSTREAM ELEVATION(FEET) = 258.00
ELEVATION DIFFERENCE(FEET) = 10.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.239
SUBAREA RUNOFF(CFS) = 0.20
TOTAL AREA(ACRES) = 0.11 TOTAL RUNOFF(CFS) = 0.20

…VMP - Hydrology & Hydraulic Report - Final.docx page 60

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS

**************************************************************************** FLOW PROCESS FROM NODE 3.15 TO NODE 3.20 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 258.00 DOWNSTREAM(FEET) = 45.50 CHANNEL LENGTH THRU SUBAREA(FEET) = 2375.00 CHANNEL SLOPE = 0.0895 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.20
FLOW VELOCITY(FEET/SEC) = 4.49 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 8.82 Tc(MIN.) = 15.09
LONGEST FLOWPATH FROM NODE 3.10 TO NODE 3.20 = 2475.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 3.20 TO NODE 3.20 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.972
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 34.37 SUBAREA RUNOFF(CFS) = 35.75 TOTAL AREA(ACRES) = 34.5 TOTAL RUNOFF(CFS) = 35.87 TC(MIN.) = 15.09

**************************************************************************** FLOW PROCESS FROM NODE 4.10 TO NODE 4.15 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 200.00
DOWNSTREAM ELEVATION(FEET) = 186.00
ELEVATION DIFFERENCE(FEET) = 14.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.239
SUBAREA RUNOFF(CFS) = 0.20
TOTAL AREA(ACRES) = 0.11 TOTAL RUNOFF(CFS) = 0.20

**************************************************************************** FLOW PROCESS FROM NODE 4.15 TO NODE 4.20 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 186.00 DOWNSTREAM(FEET) = 94.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 340.00 CHANNEL SLOPE = 0.2706 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION NOTE: CHANNEL SLOPE OF .1 WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.20
FLOW VELOCITY(FEET/SEC) = 4.74 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 1.19 Tc(MIN.) = 7.46
LONGEST FLOWPATH FROM NODE 4.10 TO NODE 4.20 = 440.00 FEET.

…VMP - Hydrology & Hydraulic Report - Final.docx page 61

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.681
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 0.90 SUBAREA RUNOFF(CFS) = 1.47 TOTAL AREA(ACRES) = 1.0 TOTAL RUNOFF(CFS) = 1.65 TC(MIN.) = 7.46

**************************************************************************** FLOW PROCESS FROM NODE 5.10 TO NODE 5.15 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 270.00
DOWNSTREAM ELEVATION(FEET) = 266.00
ELEVATION DIFFERENCE(FEET) = 4.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 8.505
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.302
SUBAREA RUNOFF(CFS) = 0.81
TOTAL AREA(ACRES) = 0.54 TOTAL RUNOFF(CFS) = 0.81

**************************************************************************** FLOW PROCESS FROM NODE 5.15 TO NODE 5.20 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 266.00 DOWNSTREAM(FEET) = 72.60 CHANNEL LENGTH THRU SUBAREA(FEET) = 1945.00 CHANNEL SLOPE = 0.0994 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.81
FLOW VELOCITY(FEET/SEC) = 4.73 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 6.85 Tc(MIN.) = 15.36
LONGEST FLOWPATH FROM NODE 5.10 TO NODE 5.20 = 2045.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.20 TO NODE 5.20 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.938
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 48.72 SUBAREA RUNOFF(CFS) = 50.11 TOTAL AREA(ACRES) = 49.3 TOTAL RUNOFF(CFS) = 50.66 TC(MIN.) = 15.36

…VMP - Hydrology & Hydraulic Report - Final.docx page 62

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
S.C.S. CURVE NUMBER (AMC II) = 96
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 126.90
DOWNSTREAM ELEVATION(FEET) = 126.10
ELEVATION DIFFERENCE(FEET) = 0.80
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 3.627
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 56.00
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.060
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.

SUBAREA RUNOFF(CFS) = 0.52
TOTAL AREA(ACRES) = 0.10 TOTAL RUNOFF(CFS) = 0.52

DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 12.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020

**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 8.34 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.44
HALFSTREET FLOOD WIDTH(FEET) = 13.76
AVERAGE FLOW VELOCITY(FEET/SEC.) = 4.08
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 1.81
STREET FLOW TRAVEL TIME(MIN.) = 5.41 Tc(MIN.) = 9.04 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.137
LIMITED INDUSTRIAL RUNOFF COEFFICIENT = .8500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 96
AREA-AVERAGE RUNOFF COEFFICIENT = 0.850
SUBAREA AREA(ACRES) = 4.30 SUBAREA RUNOFF(CFS) = 15.12 TOTAL AREA(ACRES) = 4.4 PEAK FLOW RATE(CFS) = 15.47

END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.52 HALFSTREET FLOOD WIDTH(FEET) = 18.63 FLOW VELOCITY(FEET/SEC.) = 4.74 DEPTH*VELOCITY(FT*FT/SEC.) = 2.47 *NOTE: INITIAL SUBAREA NOMOGRAPH WITH SUBAREA PARAMETERS, AND L = 1325.0 FT WITH ELEVATION-DROP = 30.4 FT, IS 22.1 CFS, WHICH EXCEEDS THE TOP-OF-CURB STREET CAPACITY AT NODE 5.40 LONGEST FLOWPATH FROM NODE 5.30 TO NODE 5.40 = 1425.00 FEET.

…VMP - Hydrology & Hydraulic Report - Final.docx page 63

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
GIVEN PIPE DIAMETER(INCH) = 24.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 15.47
PIPE TRAVEL TIME(MIN.) = 0.13 Tc(MIN.) = 9.16
LONGEST FLOWPATH FROM NODE 5.30 TO NODE 5.50 = 1507.00 FEET.

** MAIN STREAM CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 15.47 9.16 4.099 4.40
LONGEST FLOWPATH FROM NODE 5.30 TO NODE 5.40 = 1507.00 FEET.

** MEMORY BANK # 1 CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 50.66 15.36 2.938 49.26
LONGEST FLOWPATH FROM NODE 5.10 TO NODE 5.40 = 2045.00 FEET.

** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 45.70 9.16 4.099
2 61.75 15.36 2.938

COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 61.75 Tc(MIN.) = 15.36
TOTAL AREA(ACRES) = 53.7

**************************************************************************** FLOW PROCESS FROM NODE 6.10 TO NODE 6.15 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 158.00
DOWNSTREAM ELEVATION(FEET) = 148.00
ELEVATION DIFFERENCE(FEET) = 10.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.239
SUBAREA RUNOFF(CFS) = 0.22
TOTAL AREA(ACRES) = 0.12 TOTAL RUNOFF(CFS) = 0.22

**************************************************************************** FLOW PROCESS FROM NODE 6.15 TO NODE 6.20 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 148.00 DOWNSTREAM(FEET) = 108.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 290.00 CHANNEL SLOPE = 0.1379 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION NOTE: CHANNEL SLOPE OF .1 WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.22
FLOW VELOCITY(FEET/SEC) = 4.74 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 1.02 Tc(MIN.) = 7.29
LONGEST FLOWPATH FROM NODE 6.10 TO NODE 6.20 = 390.00 FEET.

****************************************************************************

…VMP - Hydrology & Hydraulic Report - Final.docx page 64

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
FLOW PROCESS FROM NODE 6.20 TO NODE 6.20 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.753
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 1.25 SUBAREA RUNOFF(CFS) = 2.08 TOTAL AREA(ACRES) = 1.4 TOTAL RUNOFF(CFS) = 2.28 TC(MIN.) = 7.29

**************************************************************************** FLOW PROCESS FROM NODE 7.10 TO NODE 7.15 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 233.00
DOWNSTREAM ELEVATION(FEET) = 226.00
ELEVATION DIFFERENCE(FEET) = 7.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 7.058
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.852
SUBAREA RUNOFF(CFS) = 0.25
TOTAL AREA(ACRES) = 0.15 TOTAL RUNOFF(CFS) = 0.25

**************************************************************************** FLOW PROCESS FROM NODE 7.15 TO NODE 7.20 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 226.00 DOWNSTREAM(FEET) = 111.60 CHANNEL LENGTH THRU SUBAREA(FEET) = 1000.00 CHANNEL SLOPE = 0.1144 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION NOTE: CHANNEL SLOPE OF .1 WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.25
FLOW VELOCITY(FEET/SEC) = 4.74 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 3.51 Tc(MIN.) = 10.57
LONGEST FLOWPATH FROM NODE 7.10 TO NODE 7.20 = 1100.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 7.20 TO NODE 7.20 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.739
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 7.02 SUBAREA RUNOFF(CFS) = 9.19 TOTAL AREA(ACRES) = 7.2 TOTAL RUNOFF(CFS) = 9.38 TC(MIN.) = 10.57
============================================================================ ============================================================================

END OF RATIONAL METHOD ANALYSIS

…VMP - Hydrology & Hydraulic Report - Final.docx page 65

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
Proposed 50-Year Storm Event Hydrology
____________________________________________________________________________ ****************************************************************************

Analysis prepared by:

civTEC
999 Corporate Dr., Suite 100
Ladera Ranch, CA 92694
ph: 949.463.8822

************************** DESCRIPTION OF STUDY ************************** * VETERANS MEMORIAL PARK * * PROPOSED CONDITION * * 50-YEAR STORM EVENT * **************************************************************************

FILE NAME: VMP_P50.DAT
TIME/DATE OF STUDY: 09:50 07/04/2024
---------------------------------------------------------------------------- USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION:
---------------------------------------------------------------------------- 2003 SAN DIEGO MANUAL CRITERIA

USER SPECIFIED STORM EVENT(YEAR) = 50.00
6-HOUR DURATION PRECIPITATION (INCHES) = 2.300
SPECIFIED MINIMUM PIPE SIZE(INCH) = 4.00
SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE = 0.95 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 26.0 10.0 0.020/0.020/0.020 0.50 1.50 0.0312 0.167 0.0150

GLOBAL STREET FLOW-DEPTH CONSTRAINTS:

1. Relative Flow-Depth = 0.00 FEET
as (Maximum Allowable Street Flow Depth) - (Top-of-Curb)

2. (Depth)*(Velocity) Constraint = 6.0 (FT*FT/S)
*SIZE PIPE WITH A FLOW CAPACITY GREATER THAN
OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.*

**************************************************************************** FLOW PROCESS FROM NODE 1.01 TO NODE 1.02 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ LAWNS, GOLF COURSES, ETC. GOOD COVER RUNOFF COEFFICIENT = .3500 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 80
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 91.80
DOWNSTREAM ELEVATION(FEET) = 82.00
ELEVATION DIFFERENCE(FEET) = 9.80
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.309
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.216
SUBAREA RUNOFF(CFS) = 0.27
TOTAL AREA(ACRES) = 0.15 TOTAL RUNOFF(CFS) = 0.27

…VMP - Hydrology & Hydraulic Report - Final.docx page 66

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
**************************************************************************** FLOW PROCESS FROM NODE 1.02 TO NODE 1.03 IS CODE = 51 ---------------------------------------------------------------------------- >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 82.00 DOWNSTREAM(FEET) = 55.80 CHANNEL LENGTH THRU SUBAREA(FEET) = 265.00 CHANNEL SLOPE = 0.0989 CHANNEL BASE(FEET) = 0.00 "Z" FACTOR = 1.000
MANNING'S FACTOR = 0.015 MAXIMUM DEPTH(FEET) = 1.00 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.963
RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT = .4100 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 82
TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 1.46 TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 8.73 AVERAGE FLOW DEPTH(FEET) = 0.41 TRAVEL TIME(MIN.) = 0.51 Tc(MIN.) = 6.81
SUBAREA AREA(ACRES) = 1.17 SUBAREA RUNOFF(CFS) = 2.38 AREA-AVERAGE RUNOFF COEFFICIENT = 0.403
TOTAL AREA(ACRES) = 1.3 PEAK FLOW RATE(CFS) = 2.64

END OF SUBAREA CHANNEL FLOW HYDRAULICS:

DEPTH(FEET) = 0.51 FLOW VELOCITY(FEET/SEC.) = 10.00 LONGEST FLOWPATH FROM NODE 1.01 TO NODE 1.03 = 365.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 1.03 TO NODE 1.04 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 54.70 DOWNSTREAM(FEET) = 54.30 FLOW LENGTH(FEET) = 20.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 9.0 INCH PIPE IS 7.2 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 6.95
ESTIMATED PIPE DIAMETER(INCH) = 9.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 2.64
PIPE TRAVEL TIME(MIN.) = 0.05 Tc(MIN.) = 6.86
LONGEST FLOWPATH FROM NODE 1.01 TO NODE 1.04 = 385.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 1.04 TO NODE 1.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 51.75 DOWNSTREAM(FEET) = 48.20 FLOW LENGTH(FEET) = 95.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 9.0 INCH PIPE IS 5.6 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 9.07
ESTIMATED PIPE DIAMETER(INCH) = 9.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 2.64
PIPE TRAVEL TIME(MIN.) = 0.17 Tc(MIN.) = 7.04
LONGEST FLOWPATH FROM NODE 1.01 TO NODE 1.20 = 480.00 FEET.

…VMP - Hydrology & Hydraulic Report - Final.docx page 67

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
ELEVATION DIFFERENCE(FEET) = 2.60
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 2.625
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 76.00
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.060
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.

SUBAREA RUNOFF(CFS) = 0.26
TOTAL AREA(ACRES) = 0.05 TOTAL RUNOFF(CFS) = 0.26

**************************************************************************** FLOW PROCESS FROM NODE 2.02 TO NODE 2.03 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 62.50 DOWNSTREAM(FEET) = 54.30 FLOW LENGTH(FEET) = 80.00 MANNING'S N = 0.011
ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 4.000
DEPTH OF FLOW IN 4.0 INCH PIPE IS 1.7 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 7.52
ESTIMATED PIPE DIAMETER(INCH) = 4.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 0.26
PIPE TRAVEL TIME(MIN.) = 0.18 Tc(MIN.) = 2.80
LONGEST FLOWPATH FROM NODE 2.01 TO NODE 2.03 = 180.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 2.03 TO NODE 2.03 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.060
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.

RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT = .4100 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 82
AREA-AVERAGE RUNOFF COEFFICIENT = 0.4661
SUBAREA AREA(ACRES) = 0.36 SUBAREA RUNOFF(CFS) = 0.89 TOTAL AREA(ACRES) = 0.4 TOTAL RUNOFF(CFS) = 1.16 TC(MIN.) = 2.80

**************************************************************************** FLOW PROCESS FROM NODE 2.03 TO NODE 2.03 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.060
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.

OFFICE PROFESSIONAL/COMMERCIAL RUNOFF COEFFICIENT = .8500 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 96
AREA-AVERAGE RUNOFF COEFFICIENT = 0.6580
SUBAREA AREA(ACRES) = 0.41 SUBAREA RUNOFF(CFS) = 2.11 TOTAL AREA(ACRES) = 0.8 TOTAL RUNOFF(CFS) = 3.27 TC(MIN.) = 2.80

…VMP - Hydrology & Hydraulic Report - Final.docx page 68

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
ESTIMATED PIPE DIAMETER(INCH) = 9.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 3.27
PIPE TRAVEL TIME(MIN.) = 0.10 Tc(MIN.) = 2.90
LONGEST FLOWPATH FROM NODE 2.01 TO NODE 2.20 = 240.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 3.01 TO NODE 3.02 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 268.00
DOWNSTREAM ELEVATION(FEET) = 258.00
ELEVATION DIFFERENCE(FEET) = 10.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.239
SUBAREA RUNOFF(CFS) = 0.20
TOTAL AREA(ACRES) = 0.11 TOTAL RUNOFF(CFS) = 0.20

**************************************************************************** FLOW PROCESS FROM NODE 3.02 TO NODE 3.03 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 258.00 DOWNSTREAM(FEET) = 87.50 CHANNEL LENGTH THRU SUBAREA(FEET) = 1815.00 CHANNEL SLOPE = 0.0939 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.20
FLOW VELOCITY(FEET/SEC) = 4.60 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 6.58 Tc(MIN.) = 12.85
LONGEST FLOWPATH FROM NODE 3.01 TO NODE 3.03 = 1915.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 3.03 TO NODE 3.03 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.297
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 18.00 SUBAREA RUNOFF(CFS) = 20.77 TOTAL AREA(ACRES) = 18.1 TOTAL RUNOFF(CFS) = 20.90 TC(MIN.) = 12.85

**************************************************************************** FLOW PROCESS FROM NODE 3.03 TO NODE 3.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 82.50 DOWNSTREAM(FEET) = 45.50 FLOW LENGTH(FEET) = 715.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 18.0 INCH PIPE IS 11.7 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 17.14
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 20.90
PIPE TRAVEL TIME(MIN.) = 0.70 Tc(MIN.) = 13.54
LONGEST FLOWPATH FROM NODE 3.01 TO NODE 3.20 = 2630.00 FEET.

****************************************************************************

…VMP - Hydrology & Hydraulic Report - Final.docx page 69

**************************************************************************** FLOW PROCESS FROM NODE 3.04 TO NODE 3.05 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ LAWNS, GOLF COURSES, ETC. GOOD COVER RUNOFF COEFFICIENT = .3500 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 80
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 216.90
DOWNSTREAM ELEVATION(FEET) = 206.00
ELEVATION DIFFERENCE(FEET) = 10.90
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.239
SUBAREA RUNOFF(CFS) = 0.44
TOTAL AREA(ACRES) = 0.24 TOTAL RUNOFF(CFS) = 0.44

**************************************************************************** FLOW PROCESS FROM NODE 3.05 TO NODE 3.06 IS CODE = 51 ---------------------------------------------------------------------------- >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 206.00 DOWNSTREAM(FEET) = 190.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 175.00 CHANNEL SLOPE = 0.0914 CHANNEL BASE(FEET) = 0.00 "Z" FACTOR = 1.000
MANNING'S FACTOR = 0.015 MAXIMUM DEPTH(FEET) = 1.00 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.025
LAWNS, GOLF COURSES, ETC. GOOD COVER RUNOFF COEFFICIENT = .3500 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 80
TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 0.73 TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 6.99 AVERAGE FLOW DEPTH(FEET) = 0.32 TRAVEL TIME(MIN.) = 0.42 Tc(MIN.) = 6.68
SUBAREA AREA(ACRES) = 0.33 SUBAREA RUNOFF(CFS) = 0.58 AREA-AVERAGE RUNOFF COEFFICIENT = 0.350
TOTAL AREA(ACRES) = 0.6 PEAK FLOW RATE(CFS) = 1.00

END OF SUBAREA CHANNEL FLOW HYDRAULICS:

DEPTH(FEET) = 0.36 FLOW VELOCITY(FEET/SEC.) = 7.59 LONGEST FLOWPATH FROM NODE 3.04 TO NODE 3.06 = 275.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 3.06 TO NODE 3.07 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 187.00 DOWNSTREAM(FEET) = 54.80 FLOW LENGTH(FEET) = 1085.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 6.0 INCH PIPE IS 2.8 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 11.16
ESTIMATED PIPE DIAMETER(INCH) = 6.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 1.00
PIPE TRAVEL TIME(MIN.) = 1.62 Tc(MIN.) = 8.30
LONGEST FLOWPATH FROM NODE 3.04 TO NODE 3.07 = 1360.00 FEET.

…VMP - Hydrology & Hydraulic Report - Final.docx page 70

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
>>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.369
RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT = .4100 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 82
AREA-AVERAGE RUNOFF COEFFICIENT = 0.4082
SUBAREA AREA(ACRES) = 17.98 SUBAREA RUNOFF(CFS) = 32.21 TOTAL AREA(ACRES) = 18.5 TOTAL RUNOFF(CFS) = 33.08 TC(MIN.) = 8.30

**************************************************************************** FLOW PROCESS FROM NODE 3.07 TO NODE 3.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 52.25 DOWNSTREAM(FEET) = 45.50 FLOW LENGTH(FEET) = 75.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 18.0 INCH PIPE IS 13.5 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 23.28
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 33.08
PIPE TRAVEL TIME(MIN.) = 0.05 Tc(MIN.) = 8.36
LONGEST FLOWPATH FROM NODE 3.04 TO NODE 3.20 = 1435.00 FEET.

** MAIN STREAM CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 33.08 8.36 4.351 18.55
LONGEST FLOWPATH FROM NODE 3.04 TO NODE 3.20 = 1435.00 FEET.

** MEMORY BANK # 1 CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 20.90 13.54 3.187 18.11
LONGEST FLOWPATH FROM NODE 3.01 TO NODE 3.20 = 2630.00 FEET.

** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 45.98 8.36 4.351
2 45.13 13.54 3.187

COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 45.98 Tc(MIN.) = 8.36
TOTAL AREA(ACRES) = 36.7

…VMP - Hydrology & Hydraulic Report - Final.docx page 71

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 204.00
DOWNSTREAM ELEVATION(FEET) = 178.00
ELEVATION DIFFERENCE(FEET) = 26.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.239
SUBAREA RUNOFF(CFS) = 0.20
TOTAL AREA(ACRES) = 0.11 TOTAL RUNOFF(CFS) = 0.20

**************************************************************************** FLOW PROCESS FROM NODE 4.02 TO NODE 4.03 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 178.00 DOWNSTREAM(FEET) = 113.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 275.00 CHANNEL SLOPE = 0.2364 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION NOTE: CHANNEL SLOPE OF .1 WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.20
FLOW VELOCITY(FEET/SEC) = 4.74 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 0.97 Tc(MIN.) = 7.23
LONGEST FLOWPATH FROM NODE 4.01 TO NODE 4.03 = 375.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 4.03 TO NODE 4.03 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.776
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 0.84 SUBAREA RUNOFF(CFS) = 1.40 TOTAL AREA(ACRES) = 0.9 TOTAL RUNOFF(CFS) = 1.59 TC(MIN.) = 7.23

**************************************************************************** FLOW PROCESS FROM NODE 4.03 TO NODE 4.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 105.30 DOWNSTREAM(FEET) = 94.00 FLOW LENGTH(FEET) = 55.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 6.0 INCH PIPE IS 3.1 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 15.25
ESTIMATED PIPE DIAMETER(INCH) = 6.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 1.59
PIPE TRAVEL TIME(MIN.) = 0.06 Tc(MIN.) = 7.29
LONGEST FLOWPATH FROM NODE 4.01 TO NODE 4.20 = 430.00 FEET.

…VMP - Hydrology & Hydraulic Report - Final.docx page 72

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 8.505
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.302
SUBAREA RUNOFF(CFS) = 0.81
TOTAL AREA(ACRES) = 0.54 TOTAL RUNOFF(CFS) = 0.81

**************************************************************************** FLOW PROCESS FROM NODE 5.02 TO NODE 5.03 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 266.00 DOWNSTREAM(FEET) = 110.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 1420.00 CHANNEL SLOPE = 0.1096 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION NOTE: CHANNEL SLOPE OF .1 WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.81
FLOW VELOCITY(FEET/SEC) = 4.74 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 4.99 Tc(MIN.) = 13.49
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.03 = 1520.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.03 TO NODE 5.03 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.194
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 16.97 SUBAREA RUNOFF(CFS) = 18.97 TOTAL AREA(ACRES) = 17.5 TOTAL RUNOFF(CFS) = 19.58 TC(MIN.) = 13.49

**************************************************************************** FLOW PROCESS FROM NODE 5.03 TO NODE 5.04 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 106.80 DOWNSTREAM(FEET) = 105.30 FLOW LENGTH(FEET) = 105.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 21.0 INCH PIPE IS 15.5 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 10.26
ESTIMATED PIPE DIAMETER(INCH) = 21.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 19.58
PIPE TRAVEL TIME(MIN.) = 0.17 Tc(MIN.) = 13.66
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.04 = 1625.00 FEET.

…VMP - Hydrology & Hydraulic Report - Final.docx page 73

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 8.505
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.302
SUBAREA RUNOFF(CFS) = 0.45
TOTAL AREA(ACRES) = 0.30 TOTAL RUNOFF(CFS) = 0.45

**************************************************************************** FLOW PROCESS FROM NODE 5.06 TO NODE 5.07 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 266.00 DOWNSTREAM(FEET) = 123.80 CHANNEL LENGTH THRU SUBAREA(FEET) = 1310.00 CHANNEL SLOPE = 0.1078 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION NOTE: CHANNEL SLOPE OF .1 WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.45
FLOW VELOCITY(FEET/SEC) = 4.74 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 4.60 Tc(MIN.) = 13.11
LONGEST FLOWPATH FROM NODE 5.05 TO NODE 5.07 = 1410.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.07 TO NODE 5.07 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.255
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 12.45 SUBAREA RUNOFF(CFS) = 14.18 TOTAL AREA(ACRES) = 12.8 TOTAL RUNOFF(CFS) = 14.52 TC(MIN.) = 13.11

**************************************************************************** FLOW PROCESS FROM NODE 5.07 TO NODE 5.04 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 117.30 DOWNSTREAM(FEET) = 105.30 FLOW LENGTH(FEET) = 150.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 15.0 INCH PIPE IS 9.2 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 18.50
ESTIMATED PIPE DIAMETER(INCH) = 15.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 14.52
PIPE TRAVEL TIME(MIN.) = 0.14 Tc(MIN.) = 13.24
LONGEST FLOWPATH FROM NODE 5.05 TO NODE 5.04 = 1560.00 FEET.

** MAIN STREAM CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 14.52 13.24 3.233 12.75
LONGEST FLOWPATH FROM NODE 5.05 TO NODE 5.04 = 1560.00 FEET.

** MEMORY BANK # 1 CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 19.58 13.66 3.168 17.51
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.04 = 1625.00 FEET.

…VMP - Hydrology & Hydraulic Report - Final.docx page 74

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 33.49 13.24 3.233
2 33.81 13.66 3.168

COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 33.81 Tc(MIN.) = 13.66
TOTAL AREA(ACRES) = 30.3

**************************************************************************** FLOW PROCESS FROM NODE 5.04 TO NODE 5.08 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 105.10 DOWNSTREAM(FEET) = 89.90 FLOW LENGTH(FEET) = 490.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 24.0 INCH PIPE IS 15.3 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 15.97
ESTIMATED PIPE DIAMETER(INCH) = 24.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 33.81
PIPE TRAVEL TIME(MIN.) = 0.51 Tc(MIN.) = 14.18
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.08 = 2115.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.09 TO NODE 5.10 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ LAWNS, GOLF COURSES, ETC. GOOD COVER RUNOFF COEFFICIENT = .3500 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 80
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 247.40
DOWNSTREAM ELEVATION(FEET) = 218.00
ELEVATION DIFFERENCE(FEET) = 29.40
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.239
SUBAREA RUNOFF(CFS) = 0.29
TOTAL AREA(ACRES) = 0.16 TOTAL RUNOFF(CFS) = 0.29

**************************************************************************** FLOW PROCESS FROM NODE 5.10 TO NODE 5.11 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 218.00 DOWNSTREAM(FEET) = 103.50 CHANNEL LENGTH THRU SUBAREA(FEET) = 780.00 CHANNEL SLOPE = 0.1468 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION NOTE: CHANNEL SLOPE OF .1 WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.29
FLOW VELOCITY(FEET/SEC) = 4.74 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL)

…VMP - Hydrology & Hydraulic Report - Final.docx page 75

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
TRAVEL TIME(MIN.) = 2.74 Tc(MIN.) = 9.01
LONGEST FLOWPATH FROM NODE 5.09 TO NODE 5.11 = 880.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.11 TO NODE 5.11 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.146
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 7.77 SUBAREA RUNOFF(CFS) = 11.27 TOTAL AREA(ACRES) = 7.9 TOTAL RUNOFF(CFS) = 11.51 TC(MIN.) = 9.01

**************************************************************************** FLOW PROCESS FROM NODE 5.11 TO NODE 5.12 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 99.00 DOWNSTREAM(FEET) = 98.00 FLOW LENGTH(FEET) = 70.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 18.0 INCH PIPE IS 12.1 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 9.08
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 11.51
PIPE TRAVEL TIME(MIN.) = 0.13 Tc(MIN.) = 9.14
LONGEST FLOWPATH FROM NODE 5.09 TO NODE 5.12 = 950.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.13 TO NODE 5.14 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 173.00
DOWNSTREAM ELEVATION(FEET) = 153.00
ELEVATION DIFFERENCE(FEET) = 20.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.239
SUBAREA RUNOFF(CFS) = 0.22
TOTAL AREA(ACRES) = 0.12 TOTAL RUNOFF(CFS) = 0.22

…VMP - Hydrology & Hydraulic Report - Final.docx page 76

**************************************************************************** FLOW PROCESS FROM NODE 5.15 TO NODE 5.15 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.837
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 0.42 SUBAREA RUNOFF(CFS) = 0.71 TOTAL AREA(ACRES) = 0.5 TOTAL RUNOFF(CFS) = 0.91 TC(MIN.) = 7.09

**************************************************************************** FLOW PROCESS FROM NODE 5.15 TO NODE 5.12 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 103.00 DOWNSTREAM(FEET) = 98.00 FLOW LENGTH(FEET) = 135.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 6.0 INCH PIPE IS 3.8 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 6.92
ESTIMATED PIPE DIAMETER(INCH) = 6.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 0.91
PIPE TRAVEL TIME(MIN.) = 0.32 Tc(MIN.) = 7.42
LONGEST FLOWPATH FROM NODE 5.13 TO NODE 5.12 = 470.00 FEET.

** MAIN STREAM CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 0.91 7.42 4.699 0.54
LONGEST FLOWPATH FROM NODE 5.13 TO NODE 5.12 = 470.00 FEET.

** MEMORY BANK # 2 CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 11.51 9.14 4.108 7.93
LONGEST FLOWPATH FROM NODE 5.09 TO NODE 5.12 = 950.00 FEET.

** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 10.26 7.42 4.699
2 12.31 9.14 4.108

COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 12.31 Tc(MIN.) = 9.14
TOTAL AREA(ACRES) = 8.5

…VMP - Hydrology & Hydraulic Report - Final.docx page 77

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
**************************************************************************** FLOW PROCESS FROM NODE 5.12 TO NODE 5.08 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 98.00 DOWNSTREAM(FEET) = 89.90 FLOW LENGTH(FEET) = 325.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 18.0 INCH PIPE IS 10.5 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 11.49
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 12.31
PIPE TRAVEL TIME(MIN.) = 0.47 Tc(MIN.) = 9.61
LONGEST FLOWPATH FROM NODE 5.09 TO NODE 5.08 = 1275.00 FEET.

** MAIN STREAM CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 12.31 9.61 3.977 8.47
LONGEST FLOWPATH FROM NODE 5.09 TO NODE 5.08 = 1275.00 FEET.

** MEMORY BANK # 1 CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 33.81 14.18 3.094 30.26
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.08 = 2115.00 FEET.

** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 35.22 9.61 3.977
2 43.38 14.18 3.094

COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 43.38 Tc(MIN.) = 14.18
TOTAL AREA(ACRES) = 38.7

**************************************************************************** FLOW PROCESS FROM NODE 5.08 TO NODE 5.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 90.00 DOWNSTREAM(FEET) = 72.60 FLOW LENGTH(FEET) = 150.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 21.0 INCH PIPE IS 12.9 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 27.95
ESTIMATED PIPE DIAMETER(INCH) = 21.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 43.38
PIPE TRAVEL TIME(MIN.) = 0.09 Tc(MIN.) = 14.27
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.20 = 2265.00 FEET.

…VMP - Hydrology & Hydraulic Report - Final.docx page 78

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
>>>>>MAIN-STREAM MEMORY COPIED ONTO MEMORY BANK # 1 <<<<< ============================================================================

**************************************************************************** FLOW PROCESS FROM NODE 5.16 TO NODE 5.17 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ LAWNS, GOLF COURSES, ETC. GOOD COVER RUNOFF COEFFICIENT = .3500 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 80
INITIAL SUBAREA FLOW-LENGTH(FEET) = 170.00
UPSTREAM ELEVATION(FEET) = 155.00
DOWNSTREAM ELEVATION(FEET) = 129.50
ELEVATION DIFFERENCE(FEET) = 25.50
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 100.00
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.239
SUBAREA RUNOFF(CFS) = 0.24
TOTAL AREA(ACRES) = 0.13 TOTAL RUNOFF(CFS) = 0.24

**************************************************************************** FLOW PROCESS FROM NODE 5.17 TO NODE 5.18 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 126.50 DOWNSTREAM(FEET) = 81.30 FLOW LENGTH(FEET) = 550.00 MANNING'S N = 0.011
ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 4.000
DEPTH OF FLOW IN 4.0 INCH PIPE IS 1.7 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 6.80
ESTIMATED PIPE DIAMETER(INCH) = 4.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 0.24
PIPE TRAVEL TIME(MIN.) = 1.35 Tc(MIN.) = 7.61
LONGEST FLOWPATH FROM NODE 5.16 TO NODE 5.18 = 720.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.18 TO NODE 5.18 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.620
RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT = .4100 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 82
AREA-AVERAGE RUNOFF COEFFICIENT = 0.4093
SUBAREA AREA(ACRES) = 11.15 SUBAREA RUNOFF(CFS) = 21.12 TOTAL AREA(ACRES) = 11.3 TOTAL RUNOFF(CFS) = 21.33 TC(MIN.) = 7.61

**************************************************************************** FLOW PROCESS FROM NODE 5.18 TO NODE 5.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 78.80 DOWNSTREAM(FEET) = 72.60 FLOW LENGTH(FEET) = 90.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 18.0 INCH PIPE IS 10.8 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 19.27
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 21.33
PIPE TRAVEL TIME(MIN.) = 0.08 Tc(MIN.) = 7.69

…VMP - Hydrology & Hydraulic Report - Final.docx page 79

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
LONGEST FLOWPATH FROM NODE 5.16 TO NODE 5.20 = 810.00 FEET.

** MAIN STREAM CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 21.33 7.69 4.590 11.28
LONGEST FLOWPATH FROM NODE 5.16 TO NODE 5.20 = 810.00 FEET.

** MEMORY BANK # 1 CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 43.38 14.27 3.082 38.73
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.20 = 2265.00 FEET.

** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 44.72 7.69 4.590
2 57.70 14.27 3.082

COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 57.70 Tc(MIN.) = 14.27
TOTAL AREA(ACRES) = 50.0

**************************************************************************** FLOW PROCESS FROM NODE 5.31 TO NODE 5.32 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ GENERAL COMMERCIAL RUNOFF COEFFICIENT = .8200
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 95
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 126.90
DOWNSTREAM ELEVATION(FEET) = 126.10
ELEVATION DIFFERENCE(FEET) = 0.80
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 4.063
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 56.00
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.060
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.

SUBAREA RUNOFF(CFS) = 0.50
TOTAL AREA(ACRES) = 0.10 TOTAL RUNOFF(CFS) = 0.50

…VMP - Hydrology & Hydraulic Report - Final.docx page 80

DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 10.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020

**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 6.59 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.38
HALFSTREET FLOOD WIDTH(FEET) = 12.57
AVERAGE FLOW VELOCITY(FEET/SEC.) = 3.88
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 1.46
STREET FLOW TRAVEL TIME(MIN.) = 5.69 Tc(MIN.) = 9.76 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.937
GENERAL COMMERCIAL RUNOFF COEFFICIENT = .8200
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 95
AREA-AVERAGE RUNOFF COEFFICIENT = 0.820
SUBAREA AREA(ACRES) = 3.65 SUBAREA RUNOFF(CFS) = 11.78 TOTAL AREA(ACRES) = 3.8 PEAK FLOW RATE(CFS) = 12.11

END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.45 HALFSTREET FLOOD WIDTH(FEET) = 16.04 FLOW VELOCITY(FEET/SEC.) = 4.50 DEPTH*VELOCITY(FT*FT/SEC.) = 2.01 *NOTE: INITIAL SUBAREA NOMOGRAPH WITH SUBAREA PARAMETERS, AND L = 1325.0 FT WITH ELEVATION-DROP = 30.4 FT, IS 18.1 CFS, WHICH EXCEEDS THE TOP-OF-CURB STREET CAPACITY AT NODE 5.33 LONGEST FLOWPATH FROM NODE 5.31 TO NODE 5.33 = 1425.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.33 TO NODE 5.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 86.00 DOWNSTREAM(FEET) = 72.60 FLOW LENGTH(FEET) = 85.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 12.0 INCH PIPE IS 7.7 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 22.73
ESTIMATED PIPE DIAMETER(INCH) = 12.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 12.11
PIPE TRAVEL TIME(MIN.) = 0.06 Tc(MIN.) = 9.82
LONGEST FLOWPATH FROM NODE 5.31 TO NODE 5.20 = 1510.00 FEET.

** MAIN STREAM CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 12.11 9.82 3.921 3.75
LONGEST FLOWPATH FROM NODE 5.31 TO NODE 5.20 = 1510.00 FEET.

** MEMORY BANK # 1 CONFLUENCE DATA **

…VMP - Hydrology & Hydraulic Report - Final.docx page 81

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 57.70 14.27 3.082 50.01
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.20 = 2265.00 FEET.

** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 51.83 9.82 3.921
2 67.22 14.27 3.082

COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 67.22 Tc(MIN.) = 14.27
TOTAL AREA(ACRES) = 53.8

**************************************************************************** FLOW PROCESS FROM NODE 6.01 TO NODE 6.02 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ LAWNS, GOLF COURSES, ETC. GOOD COVER RUNOFF COEFFICIENT = .3500 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 80
INITIAL SUBAREA FLOW-LENGTH(FEET) = 145.00
UPSTREAM ELEVATION(FEET) = 160.00
DOWNSTREAM ELEVATION(FEET) = 129.50
ELEVATION DIFFERENCE(FEET) = 30.50
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 100.00
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.239
SUBAREA RUNOFF(CFS) = 0.31
TOTAL AREA(ACRES) = 0.17 TOTAL RUNOFF(CFS) = 0.31

**************************************************************************** FLOW PROCESS FROM NODE 6.02 TO NODE 6.03 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 126.00 DOWNSTREAM(FEET) = 108.30 FLOW LENGTH(FEET) = 415.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 6.0 INCH PIPE IS 2.0 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 5.55
ESTIMATED PIPE DIAMETER(INCH) = 6.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 0.31
PIPE TRAVEL TIME(MIN.) = 1.25 Tc(MIN.) = 7.51
LONGEST FLOWPATH FROM NODE 6.01 TO NODE 6.03 = 560.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 6.03 TO NODE 6.03 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.660
RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT = .4100 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 82
AREA-AVERAGE RUNOFF COEFFICIENT = 0.4026

…VMP - Hydrology & Hydraulic Report - Final.docx page 82

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
SUBAREA AREA(ACRES) = 1.20 SUBAREA RUNOFF(CFS) = 2.29 TOTAL AREA(ACRES) = 1.4 TOTAL RUNOFF(CFS) = 2.57 TC(MIN.) = 7.51

**************************************************************************** FLOW PROCESS FROM NODE 6.03 TO NODE 6.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 105.80 DOWNSTREAM(FEET) = 102.50 FLOW LENGTH(FEET) = 35.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 9.0 INCH PIPE IS 4.2 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 12.80
ESTIMATED PIPE DIAMETER(INCH) = 9.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 2.57
PIPE TRAVEL TIME(MIN.) = 0.05 Tc(MIN.) = 7.56
LONGEST FLOWPATH FROM NODE 6.01 TO NODE 6.20 = 595.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 7.01 TO NODE 7.02 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 233.00
DOWNSTREAM ELEVATION(FEET) = 226.00
ELEVATION DIFFERENCE(FEET) = 7.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 7.058
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.852
SUBAREA RUNOFF(CFS) = 0.25
TOTAL AREA(ACRES) = 0.15 TOTAL RUNOFF(CFS) = 0.25

**************************************************************************** FLOW PROCESS FROM NODE 7.02 TO NODE 7.20 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 226.00 DOWNSTREAM(FEET) = 111.60 CHANNEL LENGTH THRU SUBAREA(FEET) = 1000.00 CHANNEL SLOPE = 0.1144 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION NOTE: CHANNEL SLOPE OF .1 WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.25
FLOW VELOCITY(FEET/SEC) = 4.74 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 3.51 Tc(MIN.) = 10.57
LONGEST FLOWPATH FROM NODE 7.01 TO NODE 7.20 = 1100.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 7.20 TO NODE 7.20 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.739
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 7.02 SUBAREA RUNOFF(CFS) = 9.19 TOTAL AREA(ACRES) = 7.2 TOTAL RUNOFF(CFS) = 9.38 TC(MIN.) = 10.57
============================================================================ ============================================================================

END OF RATIONAL METHOD ANALYSIS

…VMP - Hydrology & Hydraulic Report - Final.docx page 83

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
Existing 100-Year Storm Event Hydrology
____________________________________________________________________________ ****************************************************************************

Analysis prepared by:

civTEC
999 Corporate Dr., Suite 100
Ladera Ranch, CA 92694
ph: 949.463.8822

************************** DESCRIPTION OF STUDY ************************** * VETERANS MEMORIAL PARK * * EXISTING CONDITION * * 100-YEAR STORM EVENT * **************************************************************************

FILE NAME: VMP_E100.DAT
TIME/DATE OF STUDY: 16:40 01/22/2023
---------------------------------------------------------------------------- USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION:
---------------------------------------------------------------------------- 2003 SAN DIEGO MANUAL CRITERIA

USER SPECIFIED STORM EVENT(YEAR) = 100.00
6-HOUR DURATION PRECIPITATION (INCHES) = 2.700
SPECIFIED MINIMUM PIPE SIZE(INCH) = 12.00
SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE = 0.95 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

GLOBAL STREET FLOW-DEPTH CONSTRAINTS:

1. Relative Flow-Depth = 1.00 FEET
as (Maximum Allowable Street Flow Depth) - (Top-of-Curb)

2. (Depth)*(Velocity) Constraint = 10.0 (FT*FT/S)
*SIZE PIPE WITH A FLOW CAPACITY GREATER THAN
OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.*

**************************************************************************** FLOW PROCESS FROM NODE 1.10 TO NODE 1.15 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 108.00
DOWNSTREAM ELEVATION(FEET) = 93.00
ELEVATION DIFFERENCE(FEET) = 15.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.150
SUBAREA RUNOFF(CFS) = 0.26
TOTAL AREA(ACRES) = 0.12 TOTAL RUNOFF(CFS) = 0.26

…VMP - Hydrology & Hydraulic Report - Final.docx page 84

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS

**************************************************************************** FLOW PROCESS FROM NODE 1.15 TO NODE 1.20 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 93.00 DOWNSTREAM(FEET) = 48.20 CHANNEL LENGTH THRU SUBAREA(FEET) = 525.00 CHANNEL SLOPE = 0.0853 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.26
FLOW VELOCITY(FEET/SEC) = 4.38 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 2.00 Tc(MIN.) = 8.26
LONGEST FLOWPATH FROM NODE 1.10 TO NODE 1.20 = 625.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 1.20 TO NODE 1.20 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.145
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 2.40 SUBAREA RUNOFF(CFS) = 4.32 TOTAL AREA(ACRES) = 2.5 TOTAL RUNOFF(CFS) = 4.54 TC(MIN.) = 8.26

**************************************************************************** FLOW PROCESS FROM NODE 2.10 TO NODE 2.20 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 105.00
UPSTREAM ELEVATION(FEET) = 59.00
DOWNSTREAM ELEVATION(FEET) = 49.30
ELEVATION DIFFERENCE(FEET) = 9.70
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.434
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 100.00
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.046
SUBAREA RUNOFF(CFS) = 1.02
TOTAL AREA(ACRES) = 0.48 TOTAL RUNOFF(CFS) = 1.02

**************************************************************************** FLOW PROCESS FROM NODE 3.10 TO NODE 3.15 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 268.00
DOWNSTREAM ELEVATION(FEET) = 258.00
ELEVATION DIFFERENCE(FEET) = 10.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.150
SUBAREA RUNOFF(CFS) = 0.24
TOTAL AREA(ACRES) = 0.11 TOTAL RUNOFF(CFS) = 0.24

…VMP - Hydrology & Hydraulic Report - Final.docx page 85

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS

**************************************************************************** FLOW PROCESS FROM NODE 3.15 TO NODE 3.20 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 258.00 DOWNSTREAM(FEET) = 45.50 CHANNEL LENGTH THRU SUBAREA(FEET) = 2375.00 CHANNEL SLOPE = 0.0895 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.24
FLOW VELOCITY(FEET/SEC) = 4.49 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 8.82 Tc(MIN.) = 15.09
LONGEST FLOWPATH FROM NODE 3.10 TO NODE 3.20 = 2475.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 3.20 TO NODE 3.20 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.489
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 34.37 SUBAREA RUNOFF(CFS) = 41.97 TOTAL AREA(ACRES) = 34.5 TOTAL RUNOFF(CFS) = 42.11 TC(MIN.) = 15.09

**************************************************************************** FLOW PROCESS FROM NODE 4.10 TO NODE 4.15 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 200.00
DOWNSTREAM ELEVATION(FEET) = 186.00
ELEVATION DIFFERENCE(FEET) = 14.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.150
SUBAREA RUNOFF(CFS) = 0.24
TOTAL AREA(ACRES) = 0.11 TOTAL RUNOFF(CFS) = 0.24

**************************************************************************** FLOW PROCESS FROM NODE 4.15 TO NODE 4.20 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 186.00 DOWNSTREAM(FEET) = 94.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 340.00 CHANNEL SLOPE = 0.2706 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION NOTE: CHANNEL SLOPE OF .1 WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.24
FLOW VELOCITY(FEET/SEC) = 4.74 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 1.19 Tc(MIN.) = 7.46
LONGEST FLOWPATH FROM NODE 4.10 TO NODE 4.20 = 440.00 FEET.

…VMP - Hydrology & Hydraulic Report - Final.docx page 86

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.495
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 0.90 SUBAREA RUNOFF(CFS) = 1.73 TOTAL AREA(ACRES) = 1.0 TOTAL RUNOFF(CFS) = 1.94 TC(MIN.) = 7.46

**************************************************************************** FLOW PROCESS FROM NODE 5.10 TO NODE 5.15 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 270.00
DOWNSTREAM ELEVATION(FEET) = 266.00
ELEVATION DIFFERENCE(FEET) = 4.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 8.505
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.050
SUBAREA RUNOFF(CFS) = 0.95
TOTAL AREA(ACRES) = 0.54 TOTAL RUNOFF(CFS) = 0.95

**************************************************************************** FLOW PROCESS FROM NODE 5.15 TO NODE 5.20 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 266.00 DOWNSTREAM(FEET) = 72.60 CHANNEL LENGTH THRU SUBAREA(FEET) = 1945.00 CHANNEL SLOPE = 0.0994 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.95
FLOW VELOCITY(FEET/SEC) = 4.73 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 6.85 Tc(MIN.) = 15.36
LONGEST FLOWPATH FROM NODE 5.10 TO NODE 5.20 = 2045.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.20 TO NODE 5.20 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.449
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 48.72 SUBAREA RUNOFF(CFS) = 58.82 TOTAL AREA(ACRES) = 49.3 TOTAL RUNOFF(CFS) = 59.47 TC(MIN.) = 15.36

…VMP - Hydrology & Hydraulic Report - Final.docx page 87

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
S.C.S. CURVE NUMBER (AMC II) = 96
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 126.90
DOWNSTREAM ELEVATION(FEET) = 126.10
ELEVATION DIFFERENCE(FEET) = 0.80
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 3.627
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 56.00
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 7.114
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.

SUBAREA RUNOFF(CFS) = 0.60
TOTAL AREA(ACRES) = 0.10 TOTAL RUNOFF(CFS) = 0.60

DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 12.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020

**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 9.88 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.46
HALFSTREET FLOOD WIDTH(FEET) = 14.70
AVERAGE FLOW VELOCITY(FEET/SEC.) = 4.28
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 1.98
STREET FLOW TRAVEL TIME(MIN.) = 5.16 Tc(MIN.) = 8.79 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.943
LIMITED INDUSTRIAL RUNOFF COEFFICIENT = .8500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 96
AREA-AVERAGE RUNOFF COEFFICIENT = 0.850
SUBAREA AREA(ACRES) = 4.30 SUBAREA RUNOFF(CFS) = 18.07 TOTAL AREA(ACRES) = 4.4 PEAK FLOW RATE(CFS) = 18.49

END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.54 HALFSTREET FLOOD WIDTH(FEET) = 21.07 FLOW VELOCITY(FEET/SEC.) = 4.94 DEPTH*VELOCITY(FT*FT/SEC.) = 2.69 *NOTE: INITIAL SUBAREA NOMOGRAPH WITH SUBAREA PARAMETERS, AND L = 1325.0 FT WITH ELEVATION-DROP = 30.4 FT, IS 26.0 CFS, WHICH EXCEEDS THE TOP-OF-CURB STREET CAPACITY AT NODE 5.40 LONGEST FLOWPATH FROM NODE 5.30 TO NODE 5.40 = 1425.00 FEET.

…VMP - Hydrology & Hydraulic Report - Final.docx page 88

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
GIVEN PIPE DIAMETER(INCH) = 24.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 18.49
PIPE TRAVEL TIME(MIN.) = 0.12 Tc(MIN.) = 8.91
LONGEST FLOWPATH FROM NODE 5.30 TO NODE 5.50 = 1507.00 FEET.

** MAIN STREAM CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 18.49 8.91 4.899 4.40
LONGEST FLOWPATH FROM NODE 5.30 TO NODE 5.40 = 1507.00 FEET.

** MEMORY BANK # 1 CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 59.47 15.36 3.449 49.26
LONGEST FLOWPATH FROM NODE 5.10 TO NODE 5.40 = 2045.00 FEET.

** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 53.01 8.91 4.899
2 72.49 15.36 3.449

COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 72.49 Tc(MIN.) = 15.36
TOTAL AREA(ACRES) = 53.7

**************************************************************************** FLOW PROCESS FROM NODE 6.10 TO NODE 6.15 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 158.00
DOWNSTREAM ELEVATION(FEET) = 148.00
ELEVATION DIFFERENCE(FEET) = 10.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.150
SUBAREA RUNOFF(CFS) = 0.26
TOTAL AREA(ACRES) = 0.12 TOTAL RUNOFF(CFS) = 0.26

**************************************************************************** FLOW PROCESS FROM NODE 6.15 TO NODE 6.20 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 148.00 DOWNSTREAM(FEET) = 108.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 290.00 CHANNEL SLOPE = 0.1379 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION NOTE: CHANNEL SLOPE OF .1 WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.26
FLOW VELOCITY(FEET/SEC) = 4.74 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 1.02 Tc(MIN.) = 7.29
LONGEST FLOWPATH FROM NODE 6.10 TO NODE 6.20 = 390.00 FEET.

****************************************************************************

…VMP - Hydrology & Hydraulic Report - Final.docx page 89

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
FLOW PROCESS FROM NODE 6.20 TO NODE 6.20 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.580
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 1.25 SUBAREA RUNOFF(CFS) = 2.44 TOTAL AREA(ACRES) = 1.4 TOTAL RUNOFF(CFS) = 2.68 TC(MIN.) = 7.29

**************************************************************************** FLOW PROCESS FROM NODE 7.10 TO NODE 7.15 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 233.00
DOWNSTREAM ELEVATION(FEET) = 226.00
ELEVATION DIFFERENCE(FEET) = 7.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 7.058
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.696
SUBAREA RUNOFF(CFS) = 0.30
TOTAL AREA(ACRES) = 0.15 TOTAL RUNOFF(CFS) = 0.30

**************************************************************************** FLOW PROCESS FROM NODE 7.15 TO NODE 7.20 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 226.00 DOWNSTREAM(FEET) = 111.60 CHANNEL LENGTH THRU SUBAREA(FEET) = 1000.00 CHANNEL SLOPE = 0.1144 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION NOTE: CHANNEL SLOPE OF .1 WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.30
FLOW VELOCITY(FEET/SEC) = 4.74 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 3.51 Tc(MIN.) = 10.57
LONGEST FLOWPATH FROM NODE 7.10 TO NODE 7.20 = 1100.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 7.20 TO NODE 7.20 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.389
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 7.02 SUBAREA RUNOFF(CFS) = 10.78 TOTAL AREA(ACRES) = 7.2 TOTAL RUNOFF(CFS) = 11.01 TC(MIN.) = 10.57
============================================================================ ============================================================================

END OF RATIONAL METHOD ANALYSIS

…VMP - Hydrology & Hydraulic Report - Final.docx page 90

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
Proposed 100-Year Storm Event Hydrology
____________________________________________________________________________ ****************************************************************************

Analysis prepared by:

civTEC
999 Corporate Dr., Suite 100
Ladera Ranch, CA 92694
ph: 949.463.8822

************************** DESCRIPTION OF STUDY ************************** * VETERANS MEMORIAL PARK * * PROPOSED CONDITION * * 100-YEAR STORM EVENT * **************************************************************************

FILE NAME: VMP_P100.DAT
TIME/DATE OF STUDY: 09:53 07/04/2024
---------------------------------------------------------------------------- USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION:
---------------------------------------------------------------------------- 2003 SAN DIEGO MANUAL CRITERIA

USER SPECIFIED STORM EVENT(YEAR) = 100.00
6-HOUR DURATION PRECIPITATION (INCHES) = 2.700
SPECIFIED MINIMUM PIPE SIZE(INCH) = 4.00
SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE = 0.95 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 26.0 10.0 0.020/0.020/0.020 0.50 1.50 0.0312 0.167 0.0150

GLOBAL STREET FLOW-DEPTH CONSTRAINTS:

1. Relative Flow-Depth = 0.00 FEET
as (Maximum Allowable Street Flow Depth) - (Top-of-Curb)

2. (Depth)*(Velocity) Constraint = 6.0 (FT*FT/S)
*SIZE PIPE WITH A FLOW CAPACITY GREATER THAN
OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.*

**************************************************************************** FLOW PROCESS FROM NODE 1.01 TO NODE 1.02 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ LAWNS, GOLF COURSES, ETC. GOOD COVER RUNOFF COEFFICIENT = .3500 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 80
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 91.80
DOWNSTREAM ELEVATION(FEET) = 82.00
ELEVATION DIFFERENCE(FEET) = 9.80
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.309
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.123
SUBAREA RUNOFF(CFS) = 0.32
TOTAL AREA(ACRES) = 0.15 TOTAL RUNOFF(CFS) = 0.32

…VMP - Hydrology & Hydraulic Report - Final.docx page 91

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
**************************************************************************** FLOW PROCESS FROM NODE 1.02 TO NODE 1.03 IS CODE = 51 ---------------------------------------------------------------------------- >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 82.00 DOWNSTREAM(FEET) = 55.80 CHANNEL LENGTH THRU SUBAREA(FEET) = 265.00 CHANNEL SLOPE = 0.0989 CHANNEL BASE(FEET) = 0.00 "Z" FACTOR = 1.000
MANNING'S FACTOR = 0.015 MAXIMUM DEPTH(FEET) = 1.00 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.833
RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT = .4100 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 82
TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 1.72 TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 8.97 AVERAGE FLOW DEPTH(FEET) = 0.44 TRAVEL TIME(MIN.) = 0.49 Tc(MIN.) = 6.80
SUBAREA AREA(ACRES) = 1.17 SUBAREA RUNOFF(CFS) = 2.80 AREA-AVERAGE RUNOFF COEFFICIENT = 0.403
TOTAL AREA(ACRES) = 1.3 PEAK FLOW RATE(CFS) = 3.10

END OF SUBAREA CHANNEL FLOW HYDRAULICS:

DEPTH(FEET) = 0.55 FLOW VELOCITY(FEET/SEC.) = 10.40 LONGEST FLOWPATH FROM NODE 1.01 TO NODE 1.03 = 365.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 1.03 TO NODE 1.04 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 54.70 DOWNSTREAM(FEET) = 54.30 FLOW LENGTH(FEET) = 20.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 12.0 INCH PIPE IS 6.2 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 7.51
ESTIMATED PIPE DIAMETER(INCH) = 12.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 3.10
PIPE TRAVEL TIME(MIN.) = 0.04 Tc(MIN.) = 6.85
LONGEST FLOWPATH FROM NODE 1.01 TO NODE 1.04 = 385.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 1.04 TO NODE 1.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 51.75 DOWNSTREAM(FEET) = 48.20 FLOW LENGTH(FEET) = 95.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 9.0 INCH PIPE IS 6.3 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 9.35
ESTIMATED PIPE DIAMETER(INCH) = 9.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 3.10
PIPE TRAVEL TIME(MIN.) = 0.17 Tc(MIN.) = 7.02
LONGEST FLOWPATH FROM NODE 1.01 TO NODE 1.20 = 480.00 FEET.

…VMP - Hydrology & Hydraulic Report - Final.docx page 92

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
ELEVATION DIFFERENCE(FEET) = 2.60
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 2.625
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 76.00
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 7.114
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.

SUBAREA RUNOFF(CFS) = 0.31
TOTAL AREA(ACRES) = 0.05 TOTAL RUNOFF(CFS) = 0.31

**************************************************************************** FLOW PROCESS FROM NODE 2.02 TO NODE 2.03 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 62.50 DOWNSTREAM(FEET) = 54.30 FLOW LENGTH(FEET) = 80.00 MANNING'S N = 0.011
ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 4.000
DEPTH OF FLOW IN 4.0 INCH PIPE IS 1.9 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 7.75
ESTIMATED PIPE DIAMETER(INCH) = 4.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 0.31
PIPE TRAVEL TIME(MIN.) = 0.17 Tc(MIN.) = 2.80
LONGEST FLOWPATH FROM NODE 2.01 TO NODE 2.03 = 180.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 2.03 TO NODE 2.03 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 7.114
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.

RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT = .4100 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 82
AREA-AVERAGE RUNOFF COEFFICIENT = 0.4661
SUBAREA AREA(ACRES) = 0.36 SUBAREA RUNOFF(CFS) = 1.05 TOTAL AREA(ACRES) = 0.4 TOTAL RUNOFF(CFS) = 1.36 TC(MIN.) = 2.80

**************************************************************************** FLOW PROCESS FROM NODE 2.03 TO NODE 2.03 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 7.114
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.

OFFICE PROFESSIONAL/COMMERCIAL RUNOFF COEFFICIENT = .8500 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 96
AREA-AVERAGE RUNOFF COEFFICIENT = 0.6580
SUBAREA AREA(ACRES) = 0.41 SUBAREA RUNOFF(CFS) = 2.48 TOTAL AREA(ACRES) = 0.8 TOTAL RUNOFF(CFS) = 3.84 TC(MIN.) = 2.80

…VMP - Hydrology & Hydraulic Report - Final.docx page 93

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
ESTIMATED PIPE DIAMETER(INCH) = 9.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 3.84
PIPE TRAVEL TIME(MIN.) = 0.10 Tc(MIN.) = 2.90
LONGEST FLOWPATH FROM NODE 2.01 TO NODE 2.20 = 240.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 3.01 TO NODE 3.02 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 268.00
DOWNSTREAM ELEVATION(FEET) = 258.00
ELEVATION DIFFERENCE(FEET) = 10.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.150
SUBAREA RUNOFF(CFS) = 0.24
TOTAL AREA(ACRES) = 0.11 TOTAL RUNOFF(CFS) = 0.24

**************************************************************************** FLOW PROCESS FROM NODE 3.02 TO NODE 3.03 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 258.00 DOWNSTREAM(FEET) = 87.50 CHANNEL LENGTH THRU SUBAREA(FEET) = 1815.00 CHANNEL SLOPE = 0.0939 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.24
FLOW VELOCITY(FEET/SEC) = 4.60 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 6.58 Tc(MIN.) = 12.85
LONGEST FLOWPATH FROM NODE 3.01 TO NODE 3.03 = 1915.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 3.03 TO NODE 3.03 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.871
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 18.00 SUBAREA RUNOFF(CFS) = 24.38 TOTAL AREA(ACRES) = 18.1 TOTAL RUNOFF(CFS) = 24.53 TC(MIN.) = 12.85

**************************************************************************** FLOW PROCESS FROM NODE 3.03 TO NODE 3.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 82.50 DOWNSTREAM(FEET) = 45.50 FLOW LENGTH(FEET) = 715.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 18.0 INCH PIPE IS 13.2 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 17.61
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 24.53
PIPE TRAVEL TIME(MIN.) = 0.68 Tc(MIN.) = 13.52
LONGEST FLOWPATH FROM NODE 3.01 TO NODE 3.20 = 2630.00 FEET.

****************************************************************************

…VMP - Hydrology & Hydraulic Report - Final.docx page 94

**************************************************************************** FLOW PROCESS FROM NODE 3.04 TO NODE 3.05 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ LAWNS, GOLF COURSES, ETC. GOOD COVER RUNOFF COEFFICIENT = .3500 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 80
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 216.90
DOWNSTREAM ELEVATION(FEET) = 206.00
ELEVATION DIFFERENCE(FEET) = 10.90
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.150
SUBAREA RUNOFF(CFS) = 0.52
TOTAL AREA(ACRES) = 0.24 TOTAL RUNOFF(CFS) = 0.52

**************************************************************************** FLOW PROCESS FROM NODE 3.05 TO NODE 3.06 IS CODE = 51 ---------------------------------------------------------------------------- >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 206.00 DOWNSTREAM(FEET) = 190.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 175.00 CHANNEL SLOPE = 0.0914 CHANNEL BASE(FEET) = 0.00 "Z" FACTOR = 1.000
MANNING'S FACTOR = 0.015 MAXIMUM DEPTH(FEET) = 1.00 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.912
LAWNS, GOLF COURSES, ETC. GOOD COVER RUNOFF COEFFICIENT = .3500 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 80
TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 0.86 TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 7.40 AVERAGE FLOW DEPTH(FEET) = 0.34 TRAVEL TIME(MIN.) = 0.39 Tc(MIN.) = 6.66
SUBAREA AREA(ACRES) = 0.33 SUBAREA RUNOFF(CFS) = 0.68 AREA-AVERAGE RUNOFF COEFFICIENT = 0.350
TOTAL AREA(ACRES) = 0.6 PEAK FLOW RATE(CFS) = 1.18

END OF SUBAREA CHANNEL FLOW HYDRAULICS:

DEPTH(FEET) = 0.39 FLOW VELOCITY(FEET/SEC.) = 7.91 LONGEST FLOWPATH FROM NODE 3.04 TO NODE 3.06 = 275.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 3.06 TO NODE 3.07 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 187.00 DOWNSTREAM(FEET) = 54.80 FLOW LENGTH(FEET) = 1085.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 6.0 INCH PIPE IS 3.1 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 11.63
ESTIMATED PIPE DIAMETER(INCH) = 6.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 1.18
PIPE TRAVEL TIME(MIN.) = 1.55 Tc(MIN.) = 8.22
LONGEST FLOWPATH FROM NODE 3.04 TO NODE 3.07 = 1360.00 FEET.

…VMP - Hydrology & Hydraulic Report - Final.docx page 95

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
>>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.164
RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT = .4100 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 82
AREA-AVERAGE RUNOFF COEFFICIENT = 0.4082
SUBAREA AREA(ACRES) = 17.98 SUBAREA RUNOFF(CFS) = 38.07 TOTAL AREA(ACRES) = 18.5 TOTAL RUNOFF(CFS) = 39.10 TC(MIN.) = 8.22

**************************************************************************** FLOW PROCESS FROM NODE 3.07 TO NODE 3.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 52.25 DOWNSTREAM(FEET) = 45.50 FLOW LENGTH(FEET) = 75.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 21.0 INCH PIPE IS 13.1 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 24.74
ESTIMATED PIPE DIAMETER(INCH) = 21.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 39.10
PIPE TRAVEL TIME(MIN.) = 0.05 Tc(MIN.) = 8.27
LONGEST FLOWPATH FROM NODE 3.04 TO NODE 3.20 = 1435.00 FEET.

** MAIN STREAM CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 39.10 8.27 5.144 18.55
LONGEST FLOWPATH FROM NODE 3.04 TO NODE 3.20 = 1435.00 FEET.

** MEMORY BANK # 1 CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 24.53 13.52 3.744 18.11
LONGEST FLOWPATH FROM NODE 3.01 TO NODE 3.20 = 2630.00 FEET.

** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 54.10 8.27 5.144
2 53.00 13.52 3.744

COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 54.10 Tc(MIN.) = 8.27
TOTAL AREA(ACRES) = 36.7

…VMP - Hydrology & Hydraulic Report - Final.docx page 96

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 204.00
DOWNSTREAM ELEVATION(FEET) = 178.00
ELEVATION DIFFERENCE(FEET) = 26.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.150
SUBAREA RUNOFF(CFS) = 0.24
TOTAL AREA(ACRES) = 0.11 TOTAL RUNOFF(CFS) = 0.24

**************************************************************************** FLOW PROCESS FROM NODE 4.02 TO NODE 4.03 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 178.00 DOWNSTREAM(FEET) = 113.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 275.00 CHANNEL SLOPE = 0.2364 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION NOTE: CHANNEL SLOPE OF .1 WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.24
FLOW VELOCITY(FEET/SEC) = 4.74 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 0.97 Tc(MIN.) = 7.23
LONGEST FLOWPATH FROM NODE 4.01 TO NODE 4.03 = 375.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 4.03 TO NODE 4.03 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.606
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 0.84 SUBAREA RUNOFF(CFS) = 1.65 TOTAL AREA(ACRES) = 0.9 TOTAL RUNOFF(CFS) = 1.86 TC(MIN.) = 7.23

**************************************************************************** FLOW PROCESS FROM NODE 4.03 TO NODE 4.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 105.30 DOWNSTREAM(FEET) = 94.00 FLOW LENGTH(FEET) = 55.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 6.0 INCH PIPE IS 3.5 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 15.82
ESTIMATED PIPE DIAMETER(INCH) = 6.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 1.86
PIPE TRAVEL TIME(MIN.) = 0.06 Tc(MIN.) = 7.29
LONGEST FLOWPATH FROM NODE 4.01 TO NODE 4.20 = 430.00 FEET.

…VMP - Hydrology & Hydraulic Report - Final.docx page 97

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 8.505
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.050
SUBAREA RUNOFF(CFS) = 0.95
TOTAL AREA(ACRES) = 0.54 TOTAL RUNOFF(CFS) = 0.95

**************************************************************************** FLOW PROCESS FROM NODE 5.02 TO NODE 5.03 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 266.00 DOWNSTREAM(FEET) = 110.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 1420.00 CHANNEL SLOPE = 0.1096 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION NOTE: CHANNEL SLOPE OF .1 WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.95
FLOW VELOCITY(FEET/SEC) = 4.74 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 4.99 Tc(MIN.) = 13.49
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.03 = 1520.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.03 TO NODE 5.03 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.750
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 16.97 SUBAREA RUNOFF(CFS) = 22.27 TOTAL AREA(ACRES) = 17.5 TOTAL RUNOFF(CFS) = 22.98 TC(MIN.) = 13.49

**************************************************************************** FLOW PROCESS FROM NODE 5.03 TO NODE 5.04 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 106.80 DOWNSTREAM(FEET) = 105.30 FLOW LENGTH(FEET) = 105.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 24.0 INCH PIPE IS 15.3 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 10.84
ESTIMATED PIPE DIAMETER(INCH) = 24.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 22.98
PIPE TRAVEL TIME(MIN.) = 0.16 Tc(MIN.) = 13.66
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.04 = 1625.00 FEET.

…VMP - Hydrology & Hydraulic Report - Final.docx page 98

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 8.505
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.050
SUBAREA RUNOFF(CFS) = 0.53
TOTAL AREA(ACRES) = 0.30 TOTAL RUNOFF(CFS) = 0.53

**************************************************************************** FLOW PROCESS FROM NODE 5.06 TO NODE 5.07 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 266.00 DOWNSTREAM(FEET) = 123.80 CHANNEL LENGTH THRU SUBAREA(FEET) = 1310.00 CHANNEL SLOPE = 0.1078 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION NOTE: CHANNEL SLOPE OF .1 WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.53
FLOW VELOCITY(FEET/SEC) = 4.74 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 4.60 Tc(MIN.) = 13.11
LONGEST FLOWPATH FROM NODE 5.05 TO NODE 5.07 = 1410.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.07 TO NODE 5.07 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.821
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 12.45 SUBAREA RUNOFF(CFS) = 16.65 TOTAL AREA(ACRES) = 12.8 TOTAL RUNOFF(CFS) = 17.05 TC(MIN.) = 13.11

**************************************************************************** FLOW PROCESS FROM NODE 5.07 TO NODE 5.04 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 117.30 DOWNSTREAM(FEET) = 105.30 FLOW LENGTH(FEET) = 150.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 15.0 INCH PIPE IS 10.2 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 19.09
ESTIMATED PIPE DIAMETER(INCH) = 15.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 17.05
PIPE TRAVEL TIME(MIN.) = 0.13 Tc(MIN.) = 13.24
LONGEST FLOWPATH FROM NODE 5.05 TO NODE 5.04 = 1560.00 FEET.

** MAIN STREAM CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 17.05 13.24 3.796 12.75
LONGEST FLOWPATH FROM NODE 5.05 TO NODE 5.04 = 1560.00 FEET.

** MEMORY BANK # 1 CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 22.98 13.66 3.721 17.51
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.04 = 1625.00 FEET.

…VMP - Hydrology & Hydraulic Report - Final.docx page 99

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 39.33 13.24 3.796
2 39.69 13.66 3.721

COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 39.69 Tc(MIN.) = 13.66
TOTAL AREA(ACRES) = 30.3

**************************************************************************** FLOW PROCESS FROM NODE 5.04 TO NODE 5.08 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 105.10 DOWNSTREAM(FEET) = 89.90 FLOW LENGTH(FEET) = 490.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 24.0 INCH PIPE IS 17.2 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 16.44
ESTIMATED PIPE DIAMETER(INCH) = 24.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 39.69
PIPE TRAVEL TIME(MIN.) = 0.50 Tc(MIN.) = 14.15
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.08 = 2115.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.09 TO NODE 5.10 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ LAWNS, GOLF COURSES, ETC. GOOD COVER RUNOFF COEFFICIENT = .3500 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 80
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 247.40
DOWNSTREAM ELEVATION(FEET) = 218.00
ELEVATION DIFFERENCE(FEET) = 29.40
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.150
SUBAREA RUNOFF(CFS) = 0.34
TOTAL AREA(ACRES) = 0.16 TOTAL RUNOFF(CFS) = 0.34

**************************************************************************** FLOW PROCESS FROM NODE 5.10 TO NODE 5.11 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 218.00 DOWNSTREAM(FEET) = 103.50 CHANNEL LENGTH THRU SUBAREA(FEET) = 780.00 CHANNEL SLOPE = 0.1468 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION NOTE: CHANNEL SLOPE OF .1 WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.34
FLOW VELOCITY(FEET/SEC) = 4.74 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL)

…VMP - Hydrology & Hydraulic Report - Final.docx page 100

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
TRAVEL TIME(MIN.) = 2.74 Tc(MIN.) = 9.01
LONGEST FLOWPATH FROM NODE 5.09 TO NODE 5.11 = 880.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.11 TO NODE 5.11 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.867
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 7.77 SUBAREA RUNOFF(CFS) = 13.23 TOTAL AREA(ACRES) = 7.9 TOTAL RUNOFF(CFS) = 13.51 TC(MIN.) = 9.01

**************************************************************************** FLOW PROCESS FROM NODE 5.11 TO NODE 5.12 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 99.00 DOWNSTREAM(FEET) = 98.00 FLOW LENGTH(FEET) = 70.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 18.0 INCH PIPE IS 13.8 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 9.30
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 13.51
PIPE TRAVEL TIME(MIN.) = 0.13 Tc(MIN.) = 9.13
LONGEST FLOWPATH FROM NODE 5.09 TO NODE 5.12 = 950.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.13 TO NODE 5.14 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 173.00
DOWNSTREAM ELEVATION(FEET) = 153.00
ELEVATION DIFFERENCE(FEET) = 20.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: THE MAXIMUM OVERLAND FLOW SLOPE, 10.%, IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.150
SUBAREA RUNOFF(CFS) = 0.26
TOTAL AREA(ACRES) = 0.12 TOTAL RUNOFF(CFS) = 0.26

…VMP - Hydrology & Hydraulic Report - Final.docx page 101

**************************************************************************** FLOW PROCESS FROM NODE 5.15 TO NODE 5.15 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.678
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 0.42 SUBAREA RUNOFF(CFS) = 0.83 TOTAL AREA(ACRES) = 0.5 TOTAL RUNOFF(CFS) = 1.07 TC(MIN.) = 7.09

**************************************************************************** FLOW PROCESS FROM NODE 5.15 TO NODE 5.12 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 103.00 DOWNSTREAM(FEET) = 98.00 FLOW LENGTH(FEET) = 135.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 6.0 INCH PIPE IS 4.3 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 7.14
ESTIMATED PIPE DIAMETER(INCH) = 6.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 1.07
PIPE TRAVEL TIME(MIN.) = 0.32 Tc(MIN.) = 7.41
LONGEST FLOWPATH FROM NODE 5.13 TO NODE 5.12 = 470.00 FEET.

** MAIN STREAM CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 1.07 7.41 5.521 0.54
LONGEST FLOWPATH FROM NODE 5.13 TO NODE 5.12 = 470.00 FEET.

** MEMORY BANK # 2 CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 13.51 9.13 4.823 7.93
LONGEST FLOWPATH FROM NODE 5.09 TO NODE 5.12 = 950.00 FEET.

** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 12.03 7.41 5.521
2 14.44 9.13 4.823

COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 14.44 Tc(MIN.) = 9.13
TOTAL AREA(ACRES) = 8.5

…VMP - Hydrology & Hydraulic Report - Final.docx page 102

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
**************************************************************************** FLOW PROCESS FROM NODE 5.12 TO NODE 5.08 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 98.00 DOWNSTREAM(FEET) = 89.90 FLOW LENGTH(FEET) = 325.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 18.0 INCH PIPE IS 11.7 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 11.88
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 14.44
PIPE TRAVEL TIME(MIN.) = 0.46 Tc(MIN.) = 9.59
LONGEST FLOWPATH FROM NODE 5.09 TO NODE 5.08 = 1275.00 FEET.

** MAIN STREAM CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 14.44 9.59 4.674 8.47
LONGEST FLOWPATH FROM NODE 5.09 TO NODE 5.08 = 1275.00 FEET.

** MEMORY BANK # 1 CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 39.69 14.15 3.636 30.26
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.08 = 2115.00 FEET.

** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 41.34 9.59 4.674
2 50.93 14.15 3.636

COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 50.93 Tc(MIN.) = 14.15
TOTAL AREA(ACRES) = 38.7

**************************************************************************** FLOW PROCESS FROM NODE 5.08 TO NODE 5.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 90.00 DOWNSTREAM(FEET) = 72.60 FLOW LENGTH(FEET) = 150.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 21.0 INCH PIPE IS 14.5 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 28.84
ESTIMATED PIPE DIAMETER(INCH) = 21.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 50.93
PIPE TRAVEL TIME(MIN.) = 0.09 Tc(MIN.) = 14.24
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.20 = 2265.00 FEET.

…VMP - Hydrology & Hydraulic Report - Final.docx page 103

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
>>>>>MAIN-STREAM MEMORY COPIED ONTO MEMORY BANK # 1 <<<<< ============================================================================

**************************************************************************** FLOW PROCESS FROM NODE 5.16 TO NODE 5.17 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ LAWNS, GOLF COURSES, ETC. GOOD COVER RUNOFF COEFFICIENT = .3500 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 80
INITIAL SUBAREA FLOW-LENGTH(FEET) = 170.00
UPSTREAM ELEVATION(FEET) = 155.00
DOWNSTREAM ELEVATION(FEET) = 129.50
ELEVATION DIFFERENCE(FEET) = 25.50
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 100.00
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.150
SUBAREA RUNOFF(CFS) = 0.28
TOTAL AREA(ACRES) = 0.13 TOTAL RUNOFF(CFS) = 0.28

**************************************************************************** FLOW PROCESS FROM NODE 5.17 TO NODE 5.18 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 126.50 DOWNSTREAM(FEET) = 81.30 FLOW LENGTH(FEET) = 550.00 MANNING'S N = 0.011
ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 4.000
DEPTH OF FLOW IN 4.0 INCH PIPE IS 1.9 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 7.01
ESTIMATED PIPE DIAMETER(INCH) = 4.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 0.28
PIPE TRAVEL TIME(MIN.) = 1.31 Tc(MIN.) = 7.57
LONGEST FLOWPATH FROM NODE 5.16 TO NODE 5.18 = 720.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.18 TO NODE 5.18 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.442
RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT = .4100 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 82
AREA-AVERAGE RUNOFF COEFFICIENT = 0.4093
SUBAREA AREA(ACRES) = 11.15 SUBAREA RUNOFF(CFS) = 24.88 TOTAL AREA(ACRES) = 11.3 TOTAL RUNOFF(CFS) = 25.13 TC(MIN.) = 7.57

**************************************************************************** FLOW PROCESS FROM NODE 5.18 TO NODE 5.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 78.80 DOWNSTREAM(FEET) = 72.60 FLOW LENGTH(FEET) = 90.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 18.0 INCH PIPE IS 12.1 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 19.93
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 25.13
PIPE TRAVEL TIME(MIN.) = 0.08 Tc(MIN.) = 7.65

…VMP - Hydrology & Hydraulic Report - Final.docx page 104

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
LONGEST FLOWPATH FROM NODE 5.16 TO NODE 5.20 = 810.00 FEET.

** MAIN STREAM CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 25.13 7.65 5.408 11.28
LONGEST FLOWPATH FROM NODE 5.16 TO NODE 5.20 = 810.00 FEET.

** MEMORY BANK # 1 CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 50.93 14.24 3.622 38.73
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.20 = 2265.00 FEET.

** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 52.49 7.65 5.408
2 67.76 14.24 3.622

COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 67.76 Tc(MIN.) = 14.24
TOTAL AREA(ACRES) = 50.0

**************************************************************************** FLOW PROCESS FROM NODE 5.31 TO NODE 5.32 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ GENERAL COMMERCIAL RUNOFF COEFFICIENT = .8200
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 95
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 126.90
DOWNSTREAM ELEVATION(FEET) = 126.10
ELEVATION DIFFERENCE(FEET) = 0.80
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 4.063
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 56.00
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 7.114
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.

SUBAREA RUNOFF(CFS) = 0.58
TOTAL AREA(ACRES) = 0.10 TOTAL RUNOFF(CFS) = 0.58

…VMP - Hydrology & Hydraulic Report - Final.docx page 105

DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 10.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020

**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 7.84 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.40
HALFSTREET FLOOD WIDTH(FEET) = 13.54
AVERAGE FLOW VELOCITY(FEET/SEC.) = 4.02
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 1.59
STREET FLOW TRAVEL TIME(MIN.) = 5.50 Tc(MIN.) = 9.56 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.683
GENERAL COMMERCIAL RUNOFF COEFFICIENT = .8200
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 95
AREA-AVERAGE RUNOFF COEFFICIENT = 0.820
SUBAREA AREA(ACRES) = 3.65 SUBAREA RUNOFF(CFS) = 14.02 TOTAL AREA(ACRES) = 3.8 PEAK FLOW RATE(CFS) = 14.40

END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.47 HALFSTREET FLOOD WIDTH(FEET) = 17.21 FLOW VELOCITY(FEET/SEC.) = 4.68 DEPTH*VELOCITY(FT*FT/SEC.) = 2.20 *NOTE: INITIAL SUBAREA NOMOGRAPH WITH SUBAREA PARAMETERS, AND L = 1325.0 FT WITH ELEVATION-DROP = 30.4 FT, IS 21.3 CFS, WHICH EXCEEDS THE TOP-OF-CURB STREET CAPACITY AT NODE 5.33 LONGEST FLOWPATH FROM NODE 5.31 TO NODE 5.33 = 1425.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 5.33 TO NODE 5.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 86.00 DOWNSTREAM(FEET) = 72.60 FLOW LENGTH(FEET) = 85.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 12.0 INCH PIPE IS 8.8 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 23.43
ESTIMATED PIPE DIAMETER(INCH) = 12.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 14.40
PIPE TRAVEL TIME(MIN.) = 0.06 Tc(MIN.) = 9.62
LONGEST FLOWPATH FROM NODE 5.31 TO NODE 5.20 = 1510.00 FEET.

** MAIN STREAM CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 14.40 9.62 4.664 3.75
LONGEST FLOWPATH FROM NODE 5.31 TO NODE 5.20 = 1510.00 FEET.

** MEMORY BANK # 1 CONFLUENCE DATA **

…VMP - Hydrology & Hydraulic Report - Final.docx page 106

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 67.76 14.24 3.622 50.01
LONGEST FLOWPATH FROM NODE 5.01 TO NODE 5.20 = 2265.00 FEET.

** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 60.18 9.62 4.664
2 78.94 14.24 3.622

COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 78.94 Tc(MIN.) = 14.24
TOTAL AREA(ACRES) = 53.8

**************************************************************************** FLOW PROCESS FROM NODE 6.01 TO NODE 6.02 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ LAWNS, GOLF COURSES, ETC. GOOD COVER RUNOFF COEFFICIENT = .3500 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 80
INITIAL SUBAREA FLOW-LENGTH(FEET) = 145.00
UPSTREAM ELEVATION(FEET) = 160.00
DOWNSTREAM ELEVATION(FEET) = 129.50
ELEVATION DIFFERENCE(FEET) = 30.50
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.267
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 100.00
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.150
SUBAREA RUNOFF(CFS) = 0.37
TOTAL AREA(ACRES) = 0.17 TOTAL RUNOFF(CFS) = 0.37

**************************************************************************** FLOW PROCESS FROM NODE 6.02 TO NODE 6.03 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 126.00 DOWNSTREAM(FEET) = 108.30 FLOW LENGTH(FEET) = 415.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 6.0 INCH PIPE IS 2.1 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 5.80
ESTIMATED PIPE DIAMETER(INCH) = 6.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 0.37
PIPE TRAVEL TIME(MIN.) = 1.19 Tc(MIN.) = 7.46
LONGEST FLOWPATH FROM NODE 6.01 TO NODE 6.03 = 560.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 6.03 TO NODE 6.03 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.496
RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT = .4100 SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 82
AREA-AVERAGE RUNOFF COEFFICIENT = 0.4026

…VMP - Hydrology & Hydraulic Report - Final.docx page 107

2.0 HYDROLOGY & HYDRAULIC CALCULATIONS
SUBAREA AREA(ACRES) = 1.20 SUBAREA RUNOFF(CFS) = 2.70 TOTAL AREA(ACRES) = 1.4 TOTAL RUNOFF(CFS) = 3.03 TC(MIN.) = 7.46

**************************************************************************** FLOW PROCESS FROM NODE 6.03 TO NODE 6.20 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 105.80 DOWNSTREAM(FEET) = 102.50 FLOW LENGTH(FEET) = 35.00 MANNING'S N = 0.011
DEPTH OF FLOW IN 9.0 INCH PIPE IS 4.6 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 13.36
ESTIMATED PIPE DIAMETER(INCH) = 9.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 3.03
PIPE TRAVEL TIME(MIN.) = 0.04 Tc(MIN.) = 7.50
LONGEST FLOWPATH FROM NODE 6.01 TO NODE 6.20 = 595.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 7.01 TO NODE 7.02 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
INITIAL SUBAREA FLOW-LENGTH(FEET) = 100.00
UPSTREAM ELEVATION(FEET) = 233.00
DOWNSTREAM ELEVATION(FEET) = 226.00
ELEVATION DIFFERENCE(FEET) = 7.00
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 7.058
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.696
SUBAREA RUNOFF(CFS) = 0.30
TOTAL AREA(ACRES) = 0.15 TOTAL RUNOFF(CFS) = 0.30

**************************************************************************** FLOW PROCESS FROM NODE 7.02 TO NODE 7.20 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 226.00 DOWNSTREAM(FEET) = 111.60 CHANNEL LENGTH THRU SUBAREA(FEET) = 1000.00 CHANNEL SLOPE = 0.1144 NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION NOTE: CHANNEL SLOPE OF .1 WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.30
FLOW VELOCITY(FEET/SEC) = 4.74 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 3.51 Tc(MIN.) = 10.57
LONGEST FLOWPATH FROM NODE 7.01 TO NODE 7.20 = 1100.00 FEET.

**************************************************************************** FLOW PROCESS FROM NODE 7.20 TO NODE 7.20 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.389
OPEN BRUSH FAIR COVER RUNOFF COEFFICIENT = .3500
SOIL CLASSIFICATION IS "D"
S.C.S. CURVE NUMBER (AMC II) = 83
AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500
SUBAREA AREA(ACRES) = 7.02 SUBAREA RUNOFF(CFS) = 10.78 TOTAL AREA(ACRES) = 7.2 TOTAL RUNOFF(CFS) = 11.01 TC(MIN.) = 10.57
============================================================================ ============================================================================

END OF RATIONAL METHOD ANALYSIS
Sediment Basin Sizing:

Q=CIA
Name P6 P24 D I
A 1.7 3.1 6.92 3.63
B1 1.7 3.1 2.84 6.45
B2 1.7 3.1 2.84 6.45
C1 1.7 3.1 12.85 2.44
C2 1.7 3.1 12.95 2.42
D 1.7 3.1 7.23 3.53
E1 1.7 3.1 13.49 2.36
E2 1.7 3.1 13.11 2.41
E3 1.7 3.1 9.01 3.06
E4 1.7 3.1 7.09 3.58
E5 1.7 3.1 7.92 3.33
E6 1.7 3.1 8.52 3.18
F 1.7 3.1 7.72 3.38
G 1.7 3.1 10.57 2.76
A_sediment= 1.2Q/V
V= 0.00028ft/s
10 year
c= 0.35
Name A (acres) Q(CFS) A_sediment (sf)Basin outfallrequired storageoffsite runon A 1.32 1.68 7191 7191 7191 84.80263
B1 0.41 0.93 3967
B2 0.41 0.93 3967 7935 7935 89.07756
C1 18.11 15.44 66189 15.44
C2 18.55 15.74 67459 133649 67459 259.7296
D 0.95 1.17 5031 5031 1.17 0
E1 17.51 14.47 62021 14.47
E2 12.75 10.73 46001 10.73
E3 7.93 8.50 36441
E4 0.54 0.68 2896
E5 11.28 13.14 56331
E6 3.75 4.17 17865 221556 113533 336.9467
F 1.37 1.62 6955 6955 6955 83.39889
G 7.17 6.94 29724 29724 6.94
203074

CASQA Traditional SWPPP Template M -1 August 2023
for the 2022 CGP
Appendix M: Weather Reports
The discharger must obtain the precipitation forecast information from the National Weather Service Forecast Office (http://forecast.weather.gov ). A printed copy with the date and time of printing should be retained in this Appendix.

CASQA Traditional SWPPP Template N -1 August 2023
for the 2022 CGP
Appendix N: Monitoring Records
Place completed BMP Inspection Forms, photographic documentation, Effluent Sampling, Receiving Water, and Dewatering Field Logs, Monitoring Exceptions, NAL Exceedance Reports, and Receiving Water Monitoring Trigger Exceptions in this appendix.

CASQA Traditional SWPPP Template O -1 August 2023
for the 2022 CGP
Appendix O: Example Storm Event Monitoring
F
orms

CASQA Traditional SWPPP Template O -2 August 2023
for the 2022 CGP
Rain Gauge Log Sheet
Construction Site Name:

WDID #:

Date
(mm/dd/yy)
Time
(24-hr) Initials Rainfall Depth
(Inches) Notes:

CASQA Traditional SWPPP Template O -3 August 2023
for the 2022 CGP
Risk Level 1, 2, 3
Visual Inspection Field Log Sheet
Date and Time of Inspection: Report Date:

Inspection Type: □ Weekly □ Pre Qualifying
P
recipitation
Event (QPE)
□ During QPE □ Post QPE □ Dewatering
D
ischarge
Site Information
Construction Site Name:

Construction stage and
completed activities:

Approximate area
of exposed site:

Weather and Observations
Date Rain Predicted to Occur: Predicted % chance of precipitation (PoP):

Predicted quantity of precipitation (QPF):

Estimate storm beginning:

(date and time)
Estimate storm
duration:_________
(hours)
Estimate time since last
storm: ________
(days or hours)
R
ain gauge
reading: _______
(inches)
Observations: If yes identify location
Odors Yes □ No □
Floating material Yes □ No □
Suspended Material Yes □ No □
Sheen Yes □ No □
Discolorations Yes □ No □
Turbidity Yes □ No □
Site Inspections
Outfalls or BMPs Evaluated Deficiencies Noted
(add additional sheets or attached detailed BMP Inspection Checklists)

Photos Taken: Yes □ No □ P hoto Reference IDs:

Corrective Actions Identified (note if SWPPP/REAP change is needed)

Inspector Information
Inspector Name: Inspector Title:

Signature: Date:

CASQA Traditional SWPPP Template O -4 August 2023
for the 2022 CGP
Risk Level 1, 2, 3
Effluent Sampling Field Log Sheets
Construction Site Name: Date: Time Start:

Sampler:

Sampling Event Type: □ Stormwater □ Dewatering Discharge □ Non-visible pollutant Field Meter Calibration
pH Meter ID No./Desc.:

Calibration Date/Time:

Turbidity Meter ID No./Desc.:

Calibration Date/Time:

Field pH and Turbidity Measurements
Discharge Location Description pH Turbidity Time

Grab Samples Collected
Discharge Location Description Sample Type Time

Additional Sampling Notes:

Time End:

CASQA Traditional SWPPP Template O -5 August 2023
for the 2022 CGP

Risk Level 3
Receiving Water Sampling Field Log Sheets
Construction Site Name: Date: Time Start:

Sampler:

Receiving Water Description and Observations
Receiving Water Name/ID:

Observations:

Odors Yes □ No □
Floating material Yes □ No □
Suspended Material Yes □ No □
Sheen Yes □ No □
Discolorations Yes □ No □
Turbidity Yes □ No □
Field Meter Calibration
pH Meter ID No./Desc.:

Calibration Date/Time:

Turbidity Meter ID No./Desc.:

Calibration Date/Time:

Field pH and Turbidity Measurements
Upstream Location
Type Result Time Notes
pH

Turbidity

Downstream Location
Type Result Time Notes
pH

Turbidity

Additional Sampling Notes:

Time End:

CASQA Traditional SWPPP Template O -6 August 2023
for the 2022 CGP
NAL Exceedance Evaluation Summary Report Page __ of __
Project Name
Project WDID
Project Location
Date of Exceedance
Type of Exceedance
NAL ☐ p H ☐ T urbidity
☐ O ther (specify)
Measurement or
Analytical Method
☐ F ield meter
(Sensitivity: )
☐ Lab method (specify)
(Minimum Level: )
(MDL: )
Calculated Daily
Average
☐ p
H pH units
☐ Turbidity NTU
Rain Gauge
Measurement inches

Visual Observations
on Day of
Exceedance

CASQA Traditional SWPPP Template O -7 August 2023
for the 2022 CGP
NAL Exceedance Evaluation Summary Report Page __ of __
Description of BMPs
in Place at Time of
Event

Initial Assessment
of Cause

Corrective Actions
Taken (deployed
after exceedance)

Additional
Corrective Actions
Proposed

Report Completed
By

(Print Name, Title)
Signature

CASQA Traditional SWPPP Template O -8 Au gust 2023
for the 2022 CGP
CHAIN-OF-CUSTODY DATE: Lab ID:

DESTINATION LAB:

REQUESTED
ANALYSIS Notes:

ATTN:

ADDRESS:

Office Phone:

Cell Phone:

SAMPLED BY:

Contact:

Project Name

Client Sample ID Sample Sample Sample Container
Date Time Matrix # Type Pres.

SENDER COMMENTS:

RELINQUISHED
BY

Signature:

Print:

Company:

Date: TIME:

LABORATORY COMMENTS: RECEIVED BY
Signature:

Print:

Company:

Date: TIME:

CASQA Traditional SWPPP Template P -1 August 2023
for the 2022 CGP
Appendix P: Field Meter Instructions

Information to be Provided by Contractor Prior to
Construction.

CASQA Traditional SWPPP Template Q -1 August 2023
for the 2022 CGP
Appendix Q: Supplemental Information

Information to be Provided by Contractor Prior to
Construction.

CASQA Traditional SWPPP Template R -1 August 2023
for the 2022 CGP
Appendix R: Active Treatment System and
P
assive Treatment Plans

Information to be Provided by Contractor Prior to
Construction.

CASQA Traditional SWPPP Template S-1 August 2023
for the 2022 CGP
Appendix S: Construction General Permit
Copies of the Construction Stormwater General Permit may be downloaded from the State Water Board website at:
http://www.waterboards.ca.gov/water_issues/programs/st ormwater/construction.shtml.

PAGE | i

CALIFORNIA STATE WATER RESOURCES CONTROL BOARD
1001 I Street Sacramento, CA 95814
https://www.waterboards.ca.gov

NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM (NPDES)

GENERAL PERMIT FOR STORMWATER DISCHARGES ASSOCIATED WITH

CONSTRUCTION AND LAND DISTURBANCE ACTIVITIES
(GENERAL PERMIT)

ORDER WQ 2022-0057-DWQ
NPDES NO. CAS000002

IT IS HEREBY ORDERED that this Order supersedes Order 2009-0009-DWQ as amended by Order 2010-0014-DWQ and 2012-0006-DWQ except for: (1) the requirement to submit annual reports by September 1, 2023, (2) enforcement purposes, and (3) as set forth in Section III.C of this Order. The discharger shall comply with the requirements in this Order to meet the provisions contained in Division 7 of the California Water Code (commencing with § 13000) and regulations adopted thereunder, and the provisions of the federal Clean Water Act and regulations and guidelines adopted thereunder.

IT IS ALSO HEREBY ORDERED that on or after December 17, 2022, a discharger deploying Executive Order N-73-20 may obtain regulatory coverage through the statewide programmatic permitting option in Section III.B.4 under Order 2009-0009-DWQ as amended by Orders 2010-0014-DWQ and 2012- 0006-DWQ until September 1, 2023.

This Order was adopted by the State Water Resources
Control Board on: September 8, 2022
This Order shall become effective on: September 1, 2023 The statewide programmatic permitting option per Section III.B.4 of this Order shall become effective on: December 17, 2022 This Order shall expire on: August 31, 2028
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | ii
I, Jeanine Townsend, Clerk to the Board, do hereby certify that this Order with all attachments is a full, true, and correct copy of an Order adopted by the State Water Resources Control Board, on September 8, 2022.

AYE: Chair E. Joaquin Esquivel
Board Member Sean Maguire
Board Member Laurel Firestone
Board Member Nichole Morgan
NAY: None
ABSENT: Vice Chair Dorene D’Adamo
ABSTAIN: None

for
Jeanine Townsend
Clerk to the Board

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | iii
Table of Contents
I. FINDINGS ................................................................................................ 1 II. SCOPE OF GENERAL PERMIT COVERAGE ........................................ 8 III. OBTAINING, REVISING, AND TERMINATING PERMIT COVERAGE. 12 IV. PERMIT REQUIREMENTS .................................................................... 23 V. SITE ROLES AND PERSONNEL .......................................................... 36 VI. STANDARD PROVISIONS .................................................................... 42 VII. REGIONAL WATER BOARD AUTHORITIES ....................................... 49

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | iv

LIST OF ATTACHMENTS
Attachment A Acronyms and Terms
Attachment B Glossary
Attachment C Contacts
Attachment D Traditional Construction Risk Level Requirements Attachment D.1 Risk Determination Worksheet
Attachment D.2 Permit Registration Document Requirements Attachment E Linear Underground and Overhead Project Requirements Attachment E.1 Linear Underground and Overhead Project Area or Segment Area Type Determination
Attachment E.2 Permit Registration Document Requirements for Linear Underground and Overhead Projects
Attachment F Active Treatment System Requirements
Attachment G Requirements for the Use of Passive Treatment Technologies Attachment H Total Maximum Daily Load Implementation Requirements Applicable to Construction Stormwater Discharges
Attachment I Requirements for Dischargers Granted a California Ocean Plan Exception for Discharges to Areas of Special Biological Significance
Attachment J Dewatering Requirements
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 1
I. FINDINGS
The State Water Resources Control Board (State Water Board) finds that:

1. The Federal Water Pollution Control Act, also referred to as the Clean Water Act, prohibits certain discharges of stormwater containing pollutants to waters of the United States except in compliance with a National Pollutant Discharge Elimination System (NPDES) permit (Title 33 United States Code (U.S.C.) §§ 1311 and 1342(p); also referred to as Clean Water Act §§ 301 and 402(p)).

The United States Environmental Protection Agency (U.S. EPA) promulgates federal regulations to implement the Clean Water Act’s mandate to control pollutants in stormwater runoff discharges. (Title 40 Code of Federal Regulations (
CFR) Parts 122, 123, and 124). The federal statutes and regulations require discharges to waters of the United States comprised of stormwater associated with construction activity to obtain NPDES permit coverage (except operations that result in disturbance of less than one acre of total land area and that are not part of a larger common plan of development or sale). Construction activity includes, but is not limited to, clearing, demolition, grading, excavation, and other land disturbance activities. The NPDES permit shall require implementation of Best Available Technology Economically Achievable (BAT) and Best Conventional Pollutant Control Technology (BCT) to reduce or eliminate pollutants in stormwater runoff. The NPDES permit shall also include any additional requirements necessary to achieve applicable water quality standards.

2. Consistent with Water Code, § 13374, this NPDES permit also serves as waste discharge requirements for discharges of pollutants in stormwater runoff (stormwater discharges) associated with construction and land disturbance activities and is hereinafter referred to as General Permit.

3. A “discharger” is a person, as defined in Water Code § 13050(c), which includes companies and governmental bodies, subject to this General Permit who is responsible for compliance with this General Permit. The discharger designates the Legally Responsible Person(s) to serve as a primary signatory when required to sign, certify, and submit documents or information for this General Permit. The Legally Responsible Person(s) may also designate a Duly Authorized Representative(s) to sign, certify, and submit documents or information for this General Permit. “Discharger” and the designated “Duly Authorized Representative” are further defined in Attachment B of this General Permit.

4. This General Permit regulates discharges to waters of the United States from stormwater and authorized non-stormwater associated with construction activity from sites that disturb one or more acres of land surface, or that are part of a common plan of development or sale that disturbs more than one acre of land surface.

5. This General Permit regulates discharges to waters of the United States from stormwater and authorized non-stormwater associated with construction activities ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PA GE | 2
from all linear underground and overhead projects resulting in the disturbance of greater than or equal to one acre (Attachment E).

6. This General Permit does not preempt or supersede the authority of local stormwater management agencies to prohibit, restrict, or control stormwater discharges to municipal separate storm sewer systems or other watercourses within their jurisdictions.

7. This action to adopt a general NPDES permit is exempt from the provisions of Chapter 3 of the California Environmental Quality Act (Public Resources Code § 21100, et seq.), pursuant to § 13389 of the California Water Code.

8. Regional Water Quality Control Boards
(Regional Water Boards) establish water
quality standards in water quality control plans. The State Water Board establishes water quality standards in various statewide water quality control plans, including the California Ocean Plan and the forthcoming Inland Surface Waters, Enclosed Bays, and Estuaries of California Plan. U.S. EPA establishes water quality standards in the National Toxic Rule and the California Toxic Rule.

9. Pursuant to 40 Code of Federal Regulations § 131.12 and State Water Board Resolution
No. 68-16 (antidegradation policy), which incorporates applicable requirements of § 131.12, in high quality waters, discharges may not unreasonably affect beneficial uses, result in water quality less than the quality specified by water quality objectives, or cause a pollution or nuisance, except as allowed under the antidegradation policy. The federal antidegradation policy requires that “existing instream uses and the level of water quality necessary to protect the existing uses” are maintained and protected. If the baseline quality of a waterbody for a given constituent “exceeds levels necessary to support propagation of fish, shellfish, and wildlife and recreation in and on the water, that quality shall be maintained and protected” through the requirements of this Order unless the State Water Board makes findings that: (1) any lowering of the water quality is “necessary to accommodate important economic or social development in the area in which the waters are located”; (2) “water quality adequate to protect existing uses fully” is assured; and (3) “the highest statutory and regulatory requirements for all new and existing point sources and all cost-effective and reasonable best management practices for nonpoint source control” are achieved. For high quality waters, Resolution No. 68-16 requires findings that any lowering of water quality is “consistent with the maximum benefit to the people of the State” and “will not unreasonably affect present and anticipated beneficial use of such water and will not result in water quality less than that prescribed in the policies” and further that the discharge is subject to “waste discharge requirements which will result in the best practicable treatment or control of the discharge.”

10. The State Water Board finds that the permitted discharges authorized by this Order are consistent with the antidegradation provision of 40 CFR §131.12 and State Water Board Resolution No. 68-16, as set forth in Section I.H.2 in the Fact Sheet.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PA GE | 3

11. This General Permit serves as an NPDES permit in compliance with Clean Water Act § 402 and will be effective on September 1, 2023, except for the statewide programmatic permitting option per Section III.B.4 of this Order which will go into effect on December 17, 2022, provided the Regional Administrator of the U.S. EPA has no objection. If the U.S. EPA Regional Administrator objects to its issuance, this General Permit will not become effective until such objection is withdrawn.

12. The Regional Water Boards and the State Water Board, collectively referred to as the Water Boards, shall enforce the provisions herein following adoption and upon the effective da
te of this General Permit.

13. Stormwater discharges from dredge spoil placement that occur outside of waters of the state (upland sites) and that disturb one or more acres of land surface from construction activity are covered by this General Permit. This General Permit does not cover the discharge of dredged or fill material to waters of the state.

Construction projects that include the discharge of dredged or fill material to waters of the state should contact the applicable Regional Water Board to obtain authorization for the discharge of dredged or fill material to waters of the state.

14. The discharge of dredged or fill material to a water of the United States is regulated by the United States Army Corps of Engineers under Clean Water Act § 404, and by the Water Boards under Clean Water Act § 401. The discharge of dredged or fill material to a water outside of federal jurisdiction may be regulated by the Water Boards under the Porter-Cologne Water Quality Control Act. This General Permit does not authorize discharges of fill or dredged material regulated by the U.S. Army Corps of Engineers under CWA § 404 and does not constitute a waiver of water quality certification under CWA § 401.

15. Compliance with requirements contained in this General Permit does not supersede or constitute compliance with other regulatory requirements also applicable to discharges regulated by this General Permit, including waste discharge prohibitions in regional and statewide water quality control plans.

16. The State Water Board heard and considered all comments and testimony in a public hearing on August 4, 2021, as publicly noticed in accordance with s tate
and federal laws and regulations. The State Water Board has prepared written responses to all significant comments.

17. The Homeland Security Act of 2002 (U.S. 116 STAT. 2135 and Title 6 U.S. Code Chapter 1 § 101) requires any information provided to the Water Boards per a regulatory action taken by the Water Boards shall comply with the Homeland Security Act and other federal law that address security in the United States; the discharger should not submit any information that does not comply.

18. The discharger is required to comply with this General Permit’s conditions for all discharges associated with stormwater from construction activity and authorized non-stormwater discharges by this General Permit or another NPDES permit ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 4
issued by the State Water Board or a Regional Water Board. All other discharges are prohibited by this General Permit.

19. Unauthorized non-stormwater discharges are prohibited, including improper dumping, spills, or leakage from storage tanks or transfer areas. Non-stormwater discharges may contribute significant pollutant loads to receiving waters.

20. All discharges which contain a hazardous substance in excess of reportable quantities established in 40 Code of Federal Regulations §§ 117.3 and 302.4, are prohibited unless a separate NPDES permit has been issued to regulate those discharges.

21. Stormwater that is exposed to by-products and waste products resulting from demolition activities may transport and discharge pollutants off-site and into receiving waters.

22. In 2008, the State Water Board and the California Stormwater Quality Association (CASQA) led a group of stakeholders in developing and establishing the Construction General Permit Training Team (CGPTT). Subsequently, the CGPTT developed the training program and certification process for Qualified Stormwater Pollution Prevention Plan (SWPPP) Developer (QSD) and the Qualified SWPPP Practitioner (QSP) conducting work required by this General Permit. In 2010, CASQA and the State Water Board entered into a Memorandum of Agreement to document their respective understandings, roles, and responsibilities for the implementation of the QSD/QSP training program. The Memorandum of Agreement notes that the CASQA QSD/QSP Training Program constitutes a State Water Board-approved training course pursuant to the Construction Stormwater General Permit. The Memorandum of Agreement also documents that CASQA will continue to lead the QSD/QSP training program, with guidance from the CGPTT.

23. Per the Memorandum of Agreement, CASQA is responsible for qualifying and overseeing Trainers of Record who deliver the official QSD/QSP training program curricula in a manner consistent with the standards established by the CGPTT.

24. All California professional engineering, land surveying, and geology work is licensed by the Board for Professional Engineers, Land Surveyors, and Geologists
.1 Pursuant to the Professional Engineers Act (Bus. and Prof. Code § 6700, et seq.), all engineering work is required to be performed by a California licensed professional engineer. Pursuant to the Profession Land Surveyor’s Act (
Bus. and Prof. Code §§ 8700 – 8805), all land surveying work is required to be performed by a California licensed profession land surveyor. Pursuant to the Professional Geologist and Geophysicist’s Act (Bus. and Prof. Code §§ 7800 –

1 Department of Consumer Affairs, California Board for Professional Engineers, Land Surveyors, and Geologists website <https://www.bpelsg.ca.gov/> [as of July 2022] ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PA GE | 5
7887), all geological work is required to be performed by a California licensed professional geologist.

25. Precipitation events can occur at any time of the year in California. On-site stormwater management is necessary throughout the entire year to ensure sites implement adequate erosion and sediment controls prior to the onset of a precipitation event, even if construction is planned only during the typically dry
season.

26. Soil particles smaller than 0.02 millimeters (mm) (i.e., finer than medium silt) do not settle easily using conventional measures for sediment control (i.e., sediment basins). Fine particles discharged into surface waters cause downstream impacts to beneficial uses in the receiving water. Actively treating construction stormwater discharges with properly operated and maintained active treatment systems can reduce the turbidity level and sediment concentration in the discharge to levels that comply with receiving water limitations.

27. The State Water Board convened a Blue-Ribbon Panel (Panel) of stormwater
experts that submitted a report entitled “The Feasibility of Numeric Effluent Limits Applicable to Discharges of Stormwater Associated with Municipal, Industrial and Construction Activities,” dated June 19, 2006. The Panel concluded that numeric effluent limitations or numeric action levels are technically feasible to regulate construction stormwater discharges. The Panel concluded that numeric effluent limitations are feasible for discharges from sites that utilize an active treatment s
ystem. The Panel also concluded that numeric action levels are likely to be more commonly feasible. The previous permit (Order 2009-0009-DWQ, as amended by Orders 2010-0014-DWQ and 2012-0006-DWQ) includes numeric action levels for pH and turbidity, and specific numeric effluent limitations for active treatment system discharges. The Panel was not asked to address requirements specific to the implementation of Total Maximum Daily Loads (TMDL)
with assigned waste load allocations for construction stormwater sources.

28. The purpose of numeric action levels and associated monitoring requirements is to provide operational information regarding the performance of the site control measures used to minimize the discharge of pollutants and to protect receiving water beneficial uses from the adverse effects of construction-related stormwater and authorized non-stormwater discharges. Upon exceedance of a numeric action level, the discharger must take necessary corrective actions, including but not limited to maintenance, replacement, and/or installation of new best management practices. This General Permit relies on dischargers to implement an iterative process for best management practice to protect water quality.

Failure to implement corrective actions in response to a numeric action level exceedance is a violation of this General Permit.

29. This General Permit requires compliance with receiving water limitations based on water quality standards established in regional or statewide water quality control plans.

One of the receiving water limitations requires that construction ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PA GE | 6
stormwater discharges and authorized non-stormwater discharges not cause or contribute to an exceedance of applicable water quality standards. Water quality standards apply to the quality of the receiving water, not the quality of the construction stormwater discharge. Therefore, compliance with the receiving water limitations generally cannot be determined solely by the effluent water quality characteristics. If any discharger’s stormwater discharge causes or contributes to an exceedance of water quality standards, that discharger must implement additional BMPs or other control measures in order to attain compliance with the receiving water limitation. Compliance with water quality standards may, in some cases, require dischargers to implement controls that are more protective than controls implemented solely to comply with the technology-based requirements in this General Permit.

30. A Total Maximum Daily Load is the sum of the allowable loads of a single pollutant from all contributing point sources (waste load allocations) and non- point sources (load allocations), plus the contribution from background sources (40 Code of Federal Regulations § 130.2(i)). Discharges of stormwater from construction activities are considered point source discharges, and therefore must comply with NPDES permit requirements translated to be “consistent with the assumptions and requirements of any available waste load allocation for the discharge prepared by the state and approved by U.S. EPA pursuant to 40 Code of Federal Regulations § 130.7” (40 Code of Federal Regulations § 122.44 (
d)(1)(vii)). In addition, Water Code § 13263, subdivision (a), requires that waste discharge requirements implement any relevant water quality control plans. Many TMDLs in water quality control plans include implementation requirements that may be translated into General Permit requirements and TMDL-specific numeric action levels and numeric effluent limitations.

31. Areas of Special Biological Significance are defined in the California Ocean Plan as “those areas designated by the State Water Board as ocean areas requiring protection of species or biological communities to the extent that alteration of natural water quality is undesirable.” The California Ocean Plan prohibits the discharge of waste to Areas of Special Biological Significance unless identified in a State Water Board-approved exception.

32. The California Ocean Plan authorizes the State Water Board to grant an exception to Ca
lifornia Ocean Plan provisions where the State Water Board determines that the exception will not compromise protection of ocean waters for beneficial uses and the public interest will be served.

33. On March 20, 2012, the State Water Board adopted Resolutions 2012-0012 and Resolution 2012-0031, which contain exceptions to the California Ocean Plan for specific discharges of stormwater and non-point sources. This resolution also contains the special protections that are to be implemented for those discharges to Areas of Special Biological Significance.

34. Dischargers are only allow
ed to discharge to an Area of Special Biological
Significance when in compliance with Areas of Special Biological Significance- ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PA GE | 7
specific requirements in a State Water Board-provided exception to the California Ocean Plan granted to the specific discharger.

35. On August 19, 2014, the U.S. EPA adopted regulations requiring all NPDES permits to include requirements to implement sufficiently sensitive test methods.

This General Permit requires all laboratory analyses to be sufficiently sensitive and conducted according to test procedures under 40 Code of Federal Regulations Part 136. All analytical results less than the minimum level (reporting limit), as reported by the laboratory, will be assigned a value of zero (0) for any calculations required by this permit (e.g., numeric action level and numeric effluent limitation exceedance determinations), so long as a sufficiently sensitive test method was used as evidenced by the reported method detection limit and minimum level.

36. Specific types of passive treatment used in combination with other best management practices (BMPs) can prevent or reduce the discharge of fine particles from certain
construction activities when implemented correctly.

37. Passive treatment is the application of natural or synthetic chemicals and products to reduce turbidity in discharges through coagulation and flocculation.

Passive treatment does not rely on computerized, enclosed systems with pumps, filters, and real-time controls. Passive treatment may include pumps where they are necessary to move water around the site. The discharge of chemicals used in passive treatment can potentially cause or contribute to acute and chronic toxicity to aquatic life in receiving waters, potentially resulting in an exceedance of narrative or numeric water quality objectives in regional or statewide water quality control plans.

38. State Water Board Resolution 2005-0006, "Resolution Adopting the Concept of Sustainability as a Core Value for State Water Board Programs and Directing its Incorporation," and Resolution No. 2008-0030, “Requiring Sustainable Water Resources Management,” include performance standards for post-construction BMPs. The standards include the use of permanent post-construction BMPs that manage stormwater runoff rates to match pre-construction project site hydrology, and to
sustain and ensure the physical structure and biological integrity of aquatic ecosystems in the receiving waters. This “runoff reduction” approach is analogous in principle to low impact development and is proven to protect watersheds and waterbodies from hydrologic-based adverse changes and pollution impacts associated with the post-construction landscape.

39. Linear underground and overhead projects are not subject to post-construction requirements due to the nature of their construction to return project sites to pre- construction conditions.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 8
IT IS HEREBY ORDERED that all dischargers subject to this General Permit shall comply with the following conditions and requirements (including all conditions and requirements as set forth in the Attachments of this Order)2: State Water Board Order 2009-009-DWQ as amended by Orders 2010-0014-DWQ and 2012-0006-DWQ (previous permit) is superseded as of the effective date of this General Permit except for enforcement purposes, the Annual Report required to be submitted by September 1, 2023, and as set forth in Section III.C.

II. SCOPE OF GENERAL PERMIT COVERAGE
II.A. Traditional Construction Activities Subject to this General Permit This General Permit covers construction projects that include construction or land disturbance activities that result in a disturbance of one or more acres, or less than one acre but are part of a larger common plan of development or sale that totals one or more acres of land disturbance, such as the following:

1. Construction activity that includes, but is not limited to, clearing, grading, excavation, stockpiling, and demolition activities that expose or disturb soil.

2. Construction activity related to residential, commercial, or industrial development on lands currently used for agriculture including, but not limited to, the construction of buildings related to agriculture that are considered industrial pursuant to U.S. EPA regulations, such as dairy barns or food processing facilities.

3. Construction activity associated with oil and gas exploration, production, processing, or treatment operations or transmission facilities pursuant to 40 Code of Federal Regulations § 122.26(c)(1)(iii), which:
a. Had a discharge of stormwater resulting in the discharge of a reportable quantity for which notification is or was required pursuant to 40 Code of Federal Regulations §§ 117.21 or 302.6 at any time since November 16, 1987;
b. Had a discharge of stormwater resulting in the discharge of a reportable quantity for which notification is or was required pursuant to Code of Federal Regulations § 110.6 at any time since November 16, 1987; or c. Contributes to a violation of a water quality standard.

II.B. Traditional Construction Activities Not Subject to this General Permit This General Permit does not apply to the following construction activity:

1. Routine maintenance. Routine maintenance is defined as activities intended to maintain the original line and grade, hydraulic capacity and/or purpose of

2 The attachments are part of this General Permit; the attachments are not separate orders or documents that will be updated independently by the State Water Board.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 9
the facility. This General Permit further defines routine maintenance for road and highway projects as the replacement of the structural section, but not when the activity exposes the underlying soil or erodible subgrade. The road surface and base are not part of the subgrade. As such, those portions of a project that remove the paved road surface and base down to the erodible subgrade and/or underlying soil would not be considered routine maintenance.

2. Disturbances to land surfaces solely related to growing crops or agricultural operations such as disking, harrowing, terracing, and leveling, and soil preparation.

3. Discharges of stormwater from areas on tribal lands; construction on tribal lands is regulated by a federal permit.

4. Discharges of stormwater within the Lake Tahoe Hydrologic Unit. The Lahontan Regional Water Board has adopted its own permit to regulate stormwater discharges from construction activity in the Lake Tahoe Hydrologic Unit. Owners of construction sites in this watershed must apply for the Lahontan Regional Water Board permit rather than the statewide Construction Stormwater General Permit. Construction sites within the Lahontan region must also comply with the Lahontan Region Project Guideline for Erosion Control (R6T-2016-0010).3

5. Construction activity that disturbs less than one acre of land surface, unless part of a larger common plan of development or the sale of one or more acres of disturbed land surface.

6. Construction activity covered by an individual NPDES Permit for stormwater discharges.

7. Construction activity that is subject to the Industrial Stormwater General Permit:
a. Landfill operations as described by Standard Industrial Classification (SIC) code 4953. Landfill operators typically enroll under the Construction Stormwater General Permit for initial construction and final closure of the landfill.
b. Concrete manufacturers of prefabricated products, ready-mix concrete, or slurries that are delivered to construction sites require enrollment in the Industrial Stormwater General Permit. Examples of this industrial activity are those facilities primarily engaged in manufacturing concrete building blocks and bricks, other concrete products not building blocks and bricks,

3 Lahontan Regional Water Quality Control Board, Order R6T-2016-0010 (March 10, 2016),
https://www.waterboards.ca.gov/lahontan/water_issues/programs/storm_water/docs/r6 t_2016_0010_cgp_combined.pdf> [as of May 20, 2021]
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 10
or ready-mix concrete as categorized by Standard Industrial Classification (SIC) codes 3531, 3271, 3272, or 3273. Concrete manufacturing of prefabricated products, ready-mixed concrete, or slurries that are transported from construction sites where mixing occurs and delivered to a separate site require enrollment in the Industrial Stormwater General Permit.

8. Construction activity that discharges to combined sewer systems.

9. Discharges of stormwater identified in Clean Water Act § 402(l)(2), 33 USC § 1342(l)(2) (stormwater runoff from oil, gas, and mining operations) unless the discharge meets the conditions of 40 Code of Federal Regulations § 122.26(c)(1)(iii) as described in this General Permit.

10. Discharges of dredged or fill material to waters of the state. Those portions of the construction project that are located outside of waters of the state or waters of the United States are subject to this General Permit if the non-water portions disturb one or more acres of land.

II.C. Linear Underground and Overhead Projects Subject to this General Permit

1. Linear underground and overhead projects include, but are not limited to conveyance facilities, culverts, pipelines, or other linear corridors for:
a. The transportation of any gaseous, liquid, liquescent, and slurry material; b. Cable line or wire for the transmission of:
i. Electrical energy; or
ii. Communications, including internet, telephone, telegraph, radio, or television messages.
c. Ancillary facilities and substructures such as new access roads, helicopter landing zones, laydown yards, staging areas, substations, valve stations, etc. that primarily function as support for linear underground and overhead project construction activities.4

2. Construction support activities associated with linear underground and overhead projects include, but are not limited to:
a. Activities necessary for the installation of underground and overhead linear facilities (e.g., conduits, substructures, pipelines, towers, poles, cables, wires, connectors, switching, regulating and transforming equipment, vegetative management, and associated ancillary facilities); and

4 Regional Water Board staff may require, in writing, that the discharger obtain coverage through a traditional construction notice of intent when the construction of ancillary facilities more closely resembles traditional construction activities.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 11
b. Activities including underground utility mark-out, potholing, concrete and asphalt cutting and removal, trenching, excavating, boring and drilling, access road and pole/tower pad and cable/wire pull station, substructure installation, construction of tower footings and/or foundations, pole and tower installations, pipeline installations, welding, concrete and pavement repair or replacement, and stockpile/borrow locations.

II.D. Linear Underground and Overhead Projects Not Subject to this General Permit
This General Permit does not apply to the following linear underground and overhead project construction activity:

1. Routine maintenance projects. Routine maintenance projects are projects associated with operations and maintenance activities that are conducted on existing lines and facilities and within existing right-of-way, easements, franchise agreements, or other legally binding agreements of the discharger granting access to land. Routine maintenance projects include, but are not limited to projects that are conducted to:
a. Maintain the original purpose of the facility or hydraulic capacity; b. Update existing lines5 and facilities to comply with applicable codes, standards, and regulations regardless of if such projects result in increased capacity; and/or
c. Repair leaks.

2. Routine maintenance does not include construction of new lines or facilities resulting from compliance with applicable codes, standards, and regulations.

3. Routine maintenance projects do not include those areas of maintenance projects that are outside of an existing right-of-way, franchise, easements, or agreements. When a project must secure new areas, those areas may be subject to this General Permit based on the area of disturbed land outside the original right-of-way, easement, or agreement.

4. Linear underground and overhead project construction activity does not include field activities associated with the planning and design of a project (e.g., activities associated with route selection).

5. Tie-ins conducted immediately adjacent to “energized” or “pressurized” facilities by the discharger are not considered construction activities where all other linear underground and overhead project construction activities associated with the tie-in are covered by a Notice of Intent and SWPPP of a third party or municipal agency.

5 Update existing lines includes replacing existing lines with new materials or pipes.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 12
III. OBTAINING, REVISING, AND TERMINATING PERMIT COVERAGE III.A. Obtaining Permit Coverage for Traditional Construction Projects III.A.1. The Discharger shall obtain a Waste Discharge Identification (WDID) number prior to the commencement of construction activity by electronically certifying and submitting the following Permit Registration Documents through the State Water Board Stormwater Multiple Application and Report Tracking System (SMARTS)6:
a. Notice of Intent, including Risk Level determination as described in Attachment D.1;
b. Site Drawings and Maps;
c. Stormwater Pollution Prevention Plan (SWPPP) (see Section IV.O, below); d. Applicable plans, calculations, and other supporting documentation for compliance with existing permitted Phase I or Phase II municipal separate storm sewer system post-construction requirements or the post-construction standards of this General Permit;
e. Annual fee per the current 23 California Code of Regulations Chapter 9 fee schedule for NPDES stormwater permits; and
f. All applicable additional Permit Registration Document information as required in Attachment D.2 of this General Permit.

III.A.2. An applicant is considered to have General Permit regulatory coverage and can commence construction activity upon receipt of a WDID number generated by SMARTS. Dischargers shall post their site-specific WDID number in a site location that is viewable to the public or readily available upon request if unable to post publicly.

III.A.3. In the case of a public emergency that requires immediate construction activities involving one acre or more of land disturbance, a discharger shall submit a brief description of the emergency construction activity to the applicable Regional Water Board within five calendar days of the onset of site construction. The discharger shall then submit the required Permit Registration Documents through SMARTS within 30 calendar days of commencing site activity.

III.A.4. Failure to obtain General Permit coverage for stormwater and non-stormwater discharges covered by this General Permit to waters of the United States is a violation of the Clean Water Act and the California Water Code.

6 Dischargers are required to have a signed original Electronic Authorization Form on file with the State Water Board for each organization in SMARTS.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 13
III.B. Obtaining Permit Coverage for Linear Underground and Overhead Projects The discharger for a linear underground and overhead project shall designate a Legally Responsible Person for each of its WDIDs numbers. The discharger is responsible for enrollment under and compliance with this General Permit. The Legally Responsible Person, as defined in Attachment B of this General Permit, shall fulfill the electronic signature and certification requirements to obtain General Permit coverage (see Section VI.H, Electronic Signature and Certification Requirements.)
III.B.1. A discharger for a linear underground and overhead project shall obtain General Permit coverage under one or more applications submitted through SMARTS, per the requirements in Attachment E of this General Permit.

III.B.2. The Legally Responsible Person shall electronically certify and submit the following applicable Permit Registration Documents through SMARTS7 and obtain a WDID number prior to the commencement of any construction activities.
a. Notice of Intent, including linear underground and overhead project type determination as described in Attachment E.1;
b. Site-specific Stormwater Pollution Prevention Plan (SWPPP), Drawings, and Maps (see Section IV.O, below);
c. Annual fee per the current 23 California Code of Regulations Chapter 9 fee schedule for NPDES stormwater permits; and
d. All applicable additional Permit Registration Document information as required in Attachment E.2 of this General Permit.

III.B.3. Regulatory Coverage for linear underground and overhead project segments III.B.3.a. The discharger may separate a contiguous linear underground and overhead project into separately regulated segments. Linear underground and overhead project segments may consist of different risk types.

III.B.3.b. The discharger shall include a clear description in the Permit Registration Documents regarding how each segment relates to the overall linear underground and overhead project by identifying one or more of the following descriptions:
i. The segments are managed by separate contractors;
ii. The segments are constructed during distinct project phases; or iii. The segments are located in different topography, watersheds, or jurisdictional boundaries.

7 Dischargers are required to have a signed original Electronic Authorization Form on file with the State Water Board for each organization in SMARTS.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 14
III.B.3.c. Dischargers with corresponding linear underground and overhead project segments that cross Regional Water Board(s) boundaries (e.g., different segments of same project located within different Regional Water Board jurisdictions) must file separate Permit Registration Documents.

III.B.4. Programmatic Permitting Regulatory Coverage for linear underground and overhead projects
III.B.4.a. A discharger may submit one Notice of Intent requesting regional programmatic General Permit coverage for multiple non-contiguous linear underground and overhead projects, if the projects:
i. Are located within one Regional Water Board jurisdiction; ii. Are a group of projects of similar scopes with common construction activities; and
iii. Have the same Legally Responsible Person.

III.B.4.b. Effective December 17, 2022, a discharger deploying Executive Order N-73-20, per the requirements and due dates of the executive order, or amendments therein, may submit one Notice of Intent requesting statewide programmatic General Permit coverage for multiple non-contiguous linear underground and overhead broadband projects, where the installation of the utilities is outside of a construction project that is otherwise regulated under this General Permit.

III.B.4.b.i. A discharger deploying Executive Order N-73-20 may apply for a statewide programmatic permit for regulatory coverage under Order 2009-0009-DWQ (as amended by Orders 2010-0014-DWQ and 2012-0006-DWQ), from December 17, 2022 until September 1, 2023, by submitting the information required by Attachment E.2.

III.B.4.c. Linear underground and overhead project dischargers with programmatic permitting coverage shall submit, prior to the commencement of any construction activities for each non-contiguous site, a:
i. Common SWPPP with the Notice of Intent covering all the activities common to the projects; and
ii. Linear Construction Activity Notification for each site describing site- specific information in accordance with Attachment E.2, Section II.A.2.

III.B.5. An applicant is considered to have General Permit regulatory coverage and may commence construction activity upon receipt of a WDID number generated by SMARTS Dischargers shall post the project-specific WDID number in a site location that is visible to the public or readily available upon request if unable to post publicly.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 15
III.C. Regulatory Coverage under the Previous Permit
III.C.1. Dischargers that obtain coverage under State Water Board Order 2009-0009-DWQ, as amended by Orders 2010-0014-DWQ and 2012-0006-DWQ, (previous permit) prior to the effective date of this permit, may continue coverage under the previous permit until its regulated project(s) receive an approved Notice of Termination from the Regional Water Board, up to two years after the effective date of this General Permit. Two years after September 1, 2023, all existing Notices of Intent subject to the previous permit will be administratively terminated.

III.C.1.a. A discharger continuing regulatory coverage under the previous permit cannot increase a project’s disturbed acreage through the Change of Information process, on or after the effective date of this General Permit; the discharger must submit a Notice of Intent for coverage under this General Permit for the increase in disturbed acreage.

III.C.2. Dischargers with the previous permit’s Small Construction Rainfall Erosivity waiver may continue to operate under a project’s active waiver until it expires.

Waivers granted under the previous permit cannot be modified or extended.

III.C.3. Dischargers that submit a Notice of Termination for previous permit termination up to two years after the effective date of this General Permit and receive Notice of Termination approval from the Regional Water Board are not subject to this General Permit (unless the discharger subsequently submits new Permit Registration Documents).

III.C.4. Dischargers with coverage under the previous permit that need regulatory coverage after September 1, 2025 under this General Permit, shall submit, in SMARTS, the following items by August 31, 2025:
a. A certification of the discharger’s intent to obtain regulatory coverage under this General Permit;
b. A revised Notice of Intent and other Permit Registration Documents, revised to address new or changed requirements per this General Permit, as applicable; and
c. The applicable fee.

III.D. Small Construction Rainfall Erosivity Waiver
III.D.1. Dischargers are eligible for the Small Construction Rainfall Erosivity waiver (waiver) if:
a. The site is between one and five acres; and
b. The construction activity will take place during a period when the calculated rainfall erosivity factor is less than five.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 16
III.D.2. Dischargers with small sites that are part of a larger common plan of development, or dischargers that have programmatic permit coverage, do not qualify for a waiver unless the entire project qualifies for a waiver.

III.D.3. To request a waiver, the Legally Responsible Person shall submit a waiver application through SMARTS, and pay the appropriate fee to the State Water Board. If approved by the State Water Board, SMARTS will electronically provide the discharger with the waiver and a unique waiver identification number. The waiver is effective on the date the waiver identification number is issued and valid between the construction start and end dates, as entered in the waiver application.

III.D.4. A discharger qualifying for a waiver shall obtain a waiver identification number prior to starting any construction activities regulated by this General Permit.

III.D.5. A waiver is valid only if the correct start and end dates of construction activities are entered (and updated if necessary) through the Change of Information process in SMARTS.

III.D.6. The discharger may revise an original construction start date though the Change of Information process in SMARTS and shall provide documentation demonstrating the project had not started on the date originally submitted through SMARTS.

III.D.7. The discharger shall update the project end date through the Change of Information process in SMARTS prior to expiration of the waiver if the project completion date is anticipated to extend past the waiver expiration date. If the updated project end date results in a rainfall erosivity factor of five or greater, the discharger shall obtain coverage under this General Permit. If the discharger fails to update the project end date prior to expiration of waiver, they shall immediately obtain coverage under this General Permit.

III.D.8 The discharger shall post the unique waiver identification number in a site location that is visible to the public or readily available upon request if unable to post publicly.

III.D.9. A waiver does not provide General Permit coverage. Dischargers with a waiver are not required to comply with post-construction, sampling, monitoring, or other SWPPP requirements in this General Permit.

III.D.10. Regional Water Board staff may terminate a waiver if the Regional Water Board staff determines the discharge of stormwater runoff causes or contributes to an exceedance of a water quality standard or violates a prohibition in an applicable regional or statewide water quality control plan. The Regional Water Board Executive Officer or their delegate may require the discharger to obtain regulatory coverage under this General Permit or an NPDES permit issued by the Regional Water Board.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 17
III.E. Notice of Non-Applicability
III.E.1. A discharger claiming “No Discharge” through a Notice of Non-applicability (NONA) as set forth in Water Code § 13399.30 shall meet the following eligibility requirement:
a. The site’s physical location is not hydrologically connected to waters of the United States.

III.E.2. When claiming the “No Discharge” option, the discharger shall submit and certify via SMARTS both the NONA and a No Discharge Technical Report. The No Discharge Technical Report shall identify the site by address or parcel number and demonstrate that the site meets the eligibility requirement described above in Section III.E.1.a.

III.E.3. The No Discharge Technical Report shall be signed (wet signature and license number) by a California licensed professional engineer or geologist with hydrological expertise.

III.E.4. The Regional Water Board may require the No Discharge Technical Report to be reassessed if it determines that there are errors in the No Discharge Technical Report or if the site is hydrologically connected to waters of the United States.

III.F. Revising Permit Coverage Information
The discharger shall revise permit coverage information, as appropriate, to:

III.F.1. Update Construction Start and End Dates
III.F.1.a. The discharger shall electronically certify and submit a revised Notice of Intent through a Change of Information in SMARTS, when the construction start or end date changes, recalculating sediment risk and revising the SWPPP as appropriate. The Change of Information shall be submitted at least 14 days prior to the date that was modified, unless infeasible due to unforeseen circumstances.

III.F.1.b. If the discharger is revising the construction start date to a later date than previously submitted, the Change of Information shall contain time-stamped photo documentation depicting that construction activities have not commenced for the entirety of the site.

III.F.2. Reduce Acreage
III.F.2.a. When a portion of the site meets conditions for termination of coverage (Section III.H) or is sold/transferred to a new owner, the discharger may reduce the disturbed acreage covered under the General Permit. The discharger reducing disturbed acreage shall electronically certify and submit the following Permit Registration Document revisions in SMARTS, through a Change of Information, within 30 days of the reduction in acreage:
i. A revised Notice of Intent indicating the new site size; ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 18
ii. Photos demonstrating final stabilization, if applicable; iii. Revised site map(s) showing (as applicable) acreage currently under construction; acreage sold/transferred, and/or added; and acreage currently stabilized in accordance with the Conditions for Termination of Coverage in Section III.H below; and
iv. A revised SWPPP to match the change in acreage.

III.F.2.b. For a larger common plan of development for residential use, the discharger may, through the Change of Information process, remove residential lots from permit coverage once the lot meets the following criteria:
i. The residential lot has been sold to the individual homeowner(s) for residential use;
ii. A certificate of occupancy or equivalent document, is maintained on-site and can be made available during inspections;
iii. The lot is less than one acre of disturbance;
iv. All construction activity conducted on the lot by the discharger is complete; and
v. The discharger has temporarily stabilized any unfinished yard and landscaping areas with BMPs.

III.F.2.c. The discharger shall upload, as an attachment in SMARTS, documentation of a contract (e.g., Covenants, Conditions, and Restrictions) requiring the individual homeowner to stabilize the yard and landscaping within one year and to maintain the temporary BMPs until the yard and landscaping are stabilized.

III.F.2.d. The discharger shall maintain General Permit coverage for any site, parcel, or individual lot that has not received Change of Information or Notice of Termination approval from the Regional Water Board or obtained coverage under the new owner’s Notice of Intent.

III.F.3. Termination of Programmatic Permit Coverage for Linear Underground and Overhead Projects
III.F.3.a. Upon completion of construction activities for a specific site with linear underground and overhead project programmatic permit coverage, the discharger shall submit a Linear Construction Termination Notification for each completed linear segment.

III.F.3.b. The site must meet the termination conditions in Section III.H.3 below.

III.F.3.c. The Linear Construction Termination Notification must include photos demonstrating final stabilization.

III.F.3.d. Regional Water Board approval of the Linear Construction Termination Notification terminates coverage for the specific site.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 19
III.F.4. Increase Acreage
III.F.4.a. If the disturbed acreage of the site will increase, the discharger shall certify and submit the following Permit Registration Documents revisions in SMARTS, through a Change of Information, prior to the increase in disturbed acreage:
i. A revised Notice of Intent indicating the new site size; ii. A revised site map(s) showing (as applicable) acreage currently under construction; acreage sold, transferred, and/or added; and acreage currently stabilized in accordance with the conditions for terminating coverage in Section III.H below; and
iii. A revised SWPPP to match current site size.

III.F.4.b. The discharger shall submit the applicable fees, in accordance with the revised fee notification, within 14 calendar days of the notification date. The Change of Information will be returned if these fees are not received by the State Water Board within 14 calendar days of the notification date.

III.F.4.c. Regulatory coverage under this General Permit for the added acreage is not approved until the Regional Water Board approves the Change of Information.

III.F.4.d. If the increased acreage is greater than one-fourth mile from the existing site boundary and is an acre or larger, the discharger is required to submit a separate Notice of Intent.

III.F.5. Change in Ownership
III.F.5.a. Prior to a sale/transfer of a site, parcel, or individual lot (change of ownership), the existing discharger shall submit a Notice of Termination for change of ownership and a certification that the new owner has been notified of applicable requirements to obtain new General Permit for the qualifying activities. The existing discharger certification shall include the name, address, telephone number, and email address of the proposed new owner in the Notice of Termination submitted through SMARTS.8
III.F.5.b. General Permit coverage is not transferable to a new owner. The new discharger will need to submit their own Permit Registration Documents to obtain a new WDID number prior to continuing construction activities and/or installing final landscaping (including meeting conditions for termination of coverage). The new discharger shall enter the original project start date (initial date of disturbance) from the previous discharger(s).

8 Dischargers that are submitting a Notice of Termination for a change of ownership, where the new owner will obtain permit coverage to complete construction, are not required to comply with the requirements in Order Section III.H.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 20
III.G. Inactive Projects
III.G.1. Dischargers with projects where all construction activities (including passive treatment, active treatment systems, and/or active equipment) will be suspended for 30 days or more may submit a Change of Information through SMARTS to revise the SWPPP. The Change of Information shall include:
a. Revised site map depicting the current status of construction; and b. Photographs showing the temporary stabilization BMPs that were implemented.

III.G.2. Upon Regional Water Board approval of the Change of Information, sampling may be suspended, and monitoring and inspections may be reduced as follows:

III.G.2.a. A QSD shall visit the inactive project within 14 days of Regional Water Board approval of the Change of Information to verify that the SWPPP is being implemented accordingly. If necessary, the QSD shall amend the SWPPP to address all new conditions not previously considered through a Change of Information in SMARTS.

III.G.2.b. A QSP or trained delegate shall visually inspect the inactive project at least once every calendar month and prior to any weather pattern that is forecasted to have a 50 percent or greater chance of 0.5 inches or more in a 24-hour period. Please refer to Attachments D and E Section III.C for information pertaining to visual inspection requirements.
i. The QSP or trained delegate shall verify BMPs are functioning in accordance with the SWPPP and implement corrective actions where necessary.

III.G.2.c. The above inspections are not required during dangerous weather conditions or when access to the site is infeasible (e.g., due to snow accumulation) or unsafe.

III.G.3. Dischargers wishing to resume construction activities or the use of passive treatment, active treatment systems, and/or active equipment shall submit a Change of Information through SMARTS requesting to resume the project along with a revised site map based on current site conditions. Upon Regional Water Board approval of the Change of Information, the discharger is required to comply with all applicable requirements of this General Permit to resume construction activities at the site.

III.H. Terminating Permit Coverage
III.H.1. To terminate General Permit coverage, the discharger shall electronically certify and submit the required documentation (Section III.H.2 below) to demonstrate compliance with all General Permit coverage termination requirements, including applicable post-construction BMPs and/or low impact development features.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 21
III.H.2. The discharger shall electronically certify and submit the following through SMARTS to be considered for General Permit coverage termination:
a. A complete Notice of Termination;
b. QSP-prepared final Notice of Termination inspection with the QSP name and valid QSP certificate number;
c. A final site map; and
d. Photos demonstrating final stabilization and the implementation of applicable post-construction BMPs and/or low impact development.

III.H.3. The discharger shall certify and submit a final site map, as part of the Notice of Termination documents through SMARTS. The Notice of Termination final site map shall, at minimum, include the following:
a. Project boundaries and adjacent lands with labeled key features, such as roadways and waterbodies;
b. Developed drainage basin boundaries and discharge location points; c. Site entrances and exits, lot boundaries, roads, structures, and features related to the project that may be used as a reference; d. Specific permanent erosion control BMPs, post-construction BMPs, and low impact development features;
e. Individual erosion control BMPs (including final landscaping) identified using hatch patterns, symbols, or shading unique to each BMP; f. Location and orientation of all photos used to document final site conditions and demonstrate compliance with post-construction requirements of this General Permit; and
g. If applicable, areas of the site being transferred to new ownership, and the name and contact information of the owner.

III.H.4. The Regional Water Board will consider a site, parcel, or individual lot complete only when all portions of the site comply with all the following conditions:
a. The discharger has completed all construction activity; b. There is no greater potential for construction-related stormwater pollutants to be discharged into site runoff than prior to the construction activity; c. Construction-related equipment and temporary BMPs have been removed from the site, except as set forth in Section III.F.2.b above; d. Construction materials and wastes have been disposed of properly; e. Soils disturbed by construction activities have been permanently stabilized (final stabilization), except as set forth in Section III.F.2.b above, using materials that:

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 22
i. Have a product life that support the full and continued stabilization of the site;
ii. Achieve stabilization without becoming trash or debris; and iii. Minimize the risk of wildlife entrapment;
f. The discharger has ensured the QSP completed on-site visual inspections and verified the site complies with all Notice of Termination requirements, including installation of post-construction stormwater runoff BMPs and/or low impact development features;
g. The Legally Responsible Person has submitted the information in the Notice of Termination and has certified and submitted through SMARTS; and h. The discharger has demonstrated that the site complies with all Notice of Termination conditions above (Section III.H) and all final stabilization conditions by one of the following methods:
i. 70 percent final cover method. No computational proof required.

Requires permanent vegetative cover to be evenly established over 70 percent of all disturbed and exposed areas of soil (non-paved or non-built). In areas that naturally have low vegetative coverage (e.g., deserts), 70 percent of natural conditions of local undisturbed areas is acceptable. Photos of all site areas are required to verify compliance with the 70 percent final cover requirement;
OR
ii. Revised Universal Soil Loss Equation (RUSLE or RUSLE2) method. Computational proof required. Site conditions shall match values used in method computation. Photos of all site areas are required to verify pre-construction and post-construction conditions used in the computations;
OR
iii. Custom method. The discharger may request approval from the Regional Water Board to use a method or analytical model other than Section III.H.4.h.i and 4.h.ii above to demonstrate that the site complies with the “final stabilization” requirements. Photos of all site areas are required to verify the custom method used.

III.H.5. The Notice of Termination photo documentation for General Permit compliance verification shall include photos of the site’s final site conditions; post- construction BMPs and/or low impact development features; a description of the corresponding location, and orientation of photos as indicated on the final site map.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 23
III.H.6. The Notice of Termination shall include a long-term maintenance plan9 for the post-construction stormwater runoff BMPs and/or low impact development features being implemented.

III.H.7. The Notice of Termination will be automatically approved 30 calendar days after the date of Notice of Termination is submitted, unless, within the 30 calendar days the Regional Water Board notifies the discharger through SMARTS that the Notice of Termination has been denied, returned, or accepted for review.

III.H.8. All General Permit requirements remain in effect until the Notice of Termination is approved. The Legally Responsible Person will be notified through SMARTS communication when the discharger’s General Permit coverage and corresponding WDID number are terminated.

IV. PERMIT REQUIREMENTS
IV.A. Authorized Non-Stormwater Discharges
IV.A.1. Non-stormwater discharges from the following de-chlorinated potable and non- potable water sources are authorized if they comply with the requirements in Section IV.A.2 of this General Permit:
a. Fire-fighting activity;
b. Fire hydrant system flushing;
c. Irrigation of vegetative erosion control measures;
d. De-chlorinated potable water, including uncontaminated water line flushing; e. Hydrostatic pipe flushing and testing water;
f. Air conditioning or compressor condensate;
g. Uncontaminated groundwater or spring water from construction dewatering activities in compliance with Attachment J; and
h. Water to control dust.

IV.A.2. The above non-stormwater discharges are authorized under the following conditions:
a. The discharge is not routed through site areas with exposed soil, except for water used for dust control or to vegetation irrigation to stabilize areas; b. The discharge does not cause or contribute to an exceedance of water quality standards in the receiving water;

9 For the purposes of this requirement, a long-term maintenance plan shall be designed for a minimum of five years, and describe the responsible party(ies), schedule, and procedures needed to ensure that post-construction features are adequately maintained and functional.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 24
c. The discharge complies with other applicable requirements of this General Permit including applicable action levels, effluent limitations, and monitoring and reporting requirements;
d. The discharge is not prohibited by an applicable regional or statewide water quality control plan;
e. The discharge is in accordance with other applicable State and Regional Water Board permits; and
f. The discharge does not contain toxic constituents in toxic amounts and does not cause toxicity in the receiving water body.

IV.B. Discharge Prohibitions
IV.B.1. Dischargers shall not violate any discharge prohibitions contained in applicable water quality control plans.

IV.B.2. Discharges to Areas of Special Biological Significance (ASBS) are prohibited by the California Ocean Plan, unless granted an exception issued by the State Water Board.

IV.B.3. All discharges are prohibited except for the stormwater and non-stormwater discharges specifically authorized by this General Permit or another NPDES permit. The discharger shall notify the Regional Water Board of existing or anticipated non-stormwater discharges not authorized by this General Permit, within 24 hours of the discharge, to determine if regulatory coverage is necessary through a separate NPDES permit.

IV.B.4. All of the following discharges are prohibited:
a. Debris and trash, in accordance with State Water Board Resolution 2015-0019, the Trash Provisions of the Water Quality Control Plan for Ocean Waters of California and the Water Quality Control Plan for Inland Surface Waters, Enclosed Bays, and Estuaries of California, as applicable to construction stormwater discharges.
i. To comply with the Trash Provisions, dischargers shall implement, operate, and maintain trash management, treatment, and institutional controls to eliminate debris and trash from all stormwater discharges and authorized non-stormwater dischargers consistent with the prohibition of the discharge of debris and trash regulated by this General Permit. If the discharger is unable to comply with the prohibition of the discharge of debris and trash, the discharger must submit, for Regional Water Board Executive Office or designee approval, an amended Stormwater Pollution Prevention Plan addressing:

1. A demonstration that the discharger is unable to comply with this outright prohibition of the discharge of debris and trash; and ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 25

2. A demonstration that the discharger’s chosen combination of trash management, treatment, and institutional controls achieves full capture system equivalency.
b. Treatment chemicals except as authorized in Attachment F and G; c. Wastewater from washout or cleanout of areas, structures or equipment with concrete, grout, stucco, paint or other construction materials; d. Form-release oils and curing compounds;
e. Fuels, oils, fluids, or other materials used in vehicle and equipment operation and maintenance;
f. Soaps, solvents, or detergents (e.g., used in vehicle equipment washing or external building wash down); and
g. Toxic or hazardous substances (e.g., asbestos, lead, mercury, or PCBs).

IV.C. Effluent Limitations and Action Levels
IV.C.1. Narrative Effluent Limitations
IV.C.1.a. Stormwater discharges and authorized non-stormwater discharges regulated by this General Permit shall not contain a hazardous substance equal to or in excess of reportable quantities established in 40 Code of Federal Regulations §§ 117.3 and 302.4, unless a separate NPDES Permit has been issued to regulate those discharges.

IV.C.1.b. Dischargers shall minimize or prevent pollutants in stormwater discharges and authorized non-stormwater discharges through the use of controls, structures, and management practices set forth in the order and attachments of this General Permit that achieve best available technology (BAT) for toxic and non-conventional pollutants and best conventional technology (BCT) for conventional pollutants.

IV.C.2. Numeric Effluent Limitations10
IV.C.2.a. All dischargers implementing active treatment systems are subject to the numeric effluent limitations required in Attachment F.

IV.C.2.b. All dischargers that are Responsible Dischargers for a TMDL with a waste load allocation that was translated into a TMDL-related numeric effluent limitation, are subject to the numeric effluent limitations as indicated by Table H-2 in Attachment H.

10 Refer to Attachment B of this General Permit for the definitions of numeric effluent limitations and numeric effluent limitation exceedances.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 26
IV.C.3. Numeric Action Levels11
IV.C.3.a. All dischargers that are Responsible Dischargers for a TMDL with a waste load allocation that was translated into a TMDL-related numeric action level, are subject to the numeric action level as indicated by Table H-2 in Attachment H.

IV.C.3.b. Dischargers with dewatering activities not subject to a separate NPDES permit are subject to the numeric action levels required in Attachment J.

IV.C.3.c. For Risk Level 2 and 3 sites, refer to Attachment D, Section III.G. For Type 2 and 3 linear underground and overhead projects, refer to Attachment E, Section III.G. For stormwater and authorized non-stormwater discharges, the numeric action level for pH is provided as a range where the lower value is 6.5 pH standard units and the upper value is 8.5 pH standard units. The discharger shall report the field reading to two decimal places. A numeric action level exceedance for pH occurs when the reading, obtained per each discharge location per day of each qualifying precipitation event, is below the lower value or above the upper value, as shown in Table 1 of this Section.

IV.C.3.d. Risk Level 2 and 3 sites, refer to Attachment D, Section III.G. For Type 2 and 3 linear underground and overhead projects, refer to Attachment E, Section III.G. For stormwater and authorized non-stormwater discharges the numeric action level for turbidity is 250 Nephelometric Turbidity Units (NTU). An exceedance of the turbidity numeric action level occurs when the field reading, obtained per each discharge location per day of each qualifying event, is over 250 NTU, as shown in Table 1 of this Section.

11 Refer to Attachment B of this General permit for the definitions of numeric action levels and numeric action level exceedances.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 27
Table 1. Numeric Action Levels, Test Methods, Detection Limits, and Reporting Units
Parameter Test Method Discharger
Type
Method
Detection
Limit
Units
Numeric
Action
Level
TMDL-
Related
Pollutant
U.S. EPA-approved
test method for
specific pollutant
parameter
Responsible
Dischargers
Depends
on the test
method
mg/L
Refer to
Table H-2 in
Attachment
H
pH
Field test with
calibrated portable
instrument using
EPA approved
procedures
Risk Level 2
and 3

Risk Type 2
and 3

0.2 pH
Units
Lower
Value= 6.5

Upper
Value= 8.5
Turbidity
EPA 0180.1 and/or
field test with
calibrated portable
instrument
Risk Level 2
and 3

Risk Type 2
and 3
1 NTU 250
IV.D. Receiving Water Limitations
IV.D.1. The discharger shall ensure that stormwater discharges and authorized non- stormwater discharges to any surface or ground water will not adversely affect human health or the environment.

IV.D.2. The discharger shall ensure that stormwater discharges and authorized non- stormwater discharges will not contain pollutants in quantities that threaten to cause pollution or a public nuisance.

IV.D.3. The discharger shall ensure that stormwater discharges and authorized non- stormwater discharges will not contain pollutants that cause or contribute to an exceedance of any applicable water quality objectives or water quality standards contained in an applicable water quality control plan.

IV.D.4. Responsible Dischargers shall comply with the applicable TMDL implementation requirements in Attachment H of this General Permit, including TMDL-specific additional BMPs and site pollutant modeling, numeric action levels, and/or numeric effluent limitations.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 28
IV.E. Linear Underground and Overhead Project Requirements Dischargers with linear underground and/or overhead projects shall comply with the requirements included in Attachments E, E.1, and E.2 of this General Permit.

IV.F. Risk Level 1 Requirements
Risk Level 1 dischargers shall comply with the requirements included in Attachment D, D.1, and D.2 of this General Permit.

IV.G. Risk Level 2 Requirements
Risk Level 2 dischargers shall comply with the requirements included in Attachment D, D.1, and D.2 of this General Permit.

IV.H. Risk Level 3 Requirements
Risk Level 3 dischargers shall comply with the requirements included in Attachment D, D.1, and D.2 of this General Permit.

IV.I. Active Treatment System Requirements
Dischargers implementing an active treatment system shall comply with all of the requirements in Attachment F of this General Permit.

IV.J. Passive Treatment Requirements
Dischargers implementing passive treatment on-site shall comply with all the requirements in Attachment G of this General Permit.

IV.K. Total Maximum Daily Load Implementation Requirements IV.K.1. Responsible Dischargers are dischargers who:
a. Discharge stormwater and authorized non-stormwater directly, or through a municipal separate sewer system or other conveyance, to impaired water bodies or watersheds identified in a U.S. EPA approved total maximum daily load (TMDL) with a waste load allocation assigned to construction stormwater sources; and
b. Have one or more TMDL-specific pollutant sources present on-site with the potential to enter construction stormwater discharge, which are required to be identified in the pollutant source assessment (refer to Section IV.O.2.i below).

IV.K.2. Responsible Dischargers shall comply with the applicable requirements in Attachment H of this General Permit.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 29
IV.L. Discharges Subject to the California Ocean Plan
IV.L.1. Discharges to Ocean Waters
IV.L.1.a. Dischargers that discharge directly into ocean waters that are subject to the model monitoring provisions of the California Ocean Plan shall be deemed in compliance with applicable California Ocean Plan model monitoring provisions when in compliance with monitoring requirements of this General Permit.

IV.L.1.b. The Regional Water Boards may require a discharger that discharges directly into ocean waters who has demonstrated non-compliance with this General Permit’s monitoring requirements to develop and implement a monitoring plan in compliance with additional effluent and ocean monitoring provisions established pursuant to Water Code § 13383.

IV.L.2. Discharges Granted an Exception for Areas of Special Biological Significance (ASBS)
IV.L.2.a. Dischargers who were granted an exception to the California Ocean Plan prohibition of discharges of waste directly to an ASBS pursuant to Resolution 2012-0012 amended by Resolution 2012-0031 shall comply with the conditions and requirements set forth in Attachment I of this General Permit. Any discharger that applies for and is granted an exception to the California Ocean Plan prohibition after September 1, 2013, shall comply with the conditions and requirements set forth in the granted exception.

IV.M. Dewatering Requirements
IV.M.1. Dischargers with dewatering activities subject to a separate NPDES permit (e.g., de minimis and low threat discharges) are not subject to comply with the dewatering requirements of this General Permit as found in Attachment J and shall obtain coverage as required by the State or Regional Water Boards.

IV.M.2. Dischargers with dewatering activities not subject to a separate NPDES permit (e.g., de minimis and low threat discharges) shall comply with the dewatering requirements in Attachment J.

IV.N. Post-Construction Requirements
IV.N.1. All dischargers, other than linear underground and overhead project dischargers, shall implement BMPs to reduce runoff and pollutants in stormwater discharges that are reasonably foreseeable after all construction phases have been completed at the site (post-construction BMPs).

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 30
IV.N.2. Dischargers subject to the post-construction requirements of an existing NPDES Phase I or Phase II municipal separate storm sewer system permit are not subject to the post-construction requirements in Section IV.N.3 below, and shall submit the following items with their Permit Registration Documents through SMARTS:
a. An attachment or web-source containing the applicable NPDES Phase I or Phase II municipal separate storm sewer system permittee’s post- construction requirements; and
b. The post-construction plans and calculations submitted to, or approved by, the applicable NPDES Phase I or Phase II municipal separate storm sewer system permittee. If the discharger submitted preliminary post-construction plans and calculations as a Permit Registration Document, the discharger shall submit the approved plans and calculations within 14 days of approval by the municipal stormwater permittee, through a Change of Information in SMARTS. The discharger shall submit a Change of Information in SMARTS for any revisions to post-construction plans and calculations prior to submitting the Notice of Termination.

IV.N.3. All dischargers, other than linear underground and overhead project dischargers or dischargers subject to the post-construction requirements of an existing NPDES Phase I or Phase II municipal separate storm sewer system permit, shall comply with the following post-construction runoff reduction requirements.

The discharger shall comply with this General Permit’s post-construction requirements if the Permit Registration Documents were submitted prior to the effective date of applicable post-construction requirements of the corresponding NPDES Phase I or Phase II municipal stormwater permit.

IV.N.4. The discharger shall use non-structural and/or structural measures to replicate the pre-construction water balance (for this General Permit, defined as the volume of rainfall that ends up as runoff) for the smallest storms up to and including the 85th percentile, 24-hour precipitation event (or the smallest precipitation event that generates runoff, whichever is larger).

IV.N.5. For sites with disturbed area exceeding two acres, the discharger shall preserve the pre-construction drainage density (miles of stream length per square mile of drainage area) for all drainage areas within the area serving a first order stream12 or larger stream and ensure that post-project runoff time of concentration is equal to or greater than pre-project time of concentration.

IV.N.6. The discharger shall certify and submit post-construction plans, calculations, and other supporting documentation as a Permit Registration Document in SMARTS. The discharger shall submit a Change of Information in SMARTS for

12 A first order stream is defined as a stream with no tributaries.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 31
any revisions to post-construction plans and calculations prior to submitting the Notice of Termination.

IV.N.7. Regional Water Board staff may review post-construction plans, calculations, and other supporting documentation to verify that the post-construction water balance is accurate; and may request that the discharger make revisions if necessary.

IV.N.8. The discharger may use the contact information found online or in Attachment C to request Regional Water Board staff review post-construction plans, calculations, and other supporting documentation prior to and during construction.

IV.O. Stormwater Pollution Prevention Plan Requirements IV.O.1. The discharger shall ensure the site’s SWPPP complies with the below conditions:
a. A site-specific SWPPP is developed, and amended as necessary, by a QSD. The discharger is responsible for keeping the SWPPP and associated documents updated in SMARTS to reflect current site conditions and construction activities.
b. Trained personnel and BMP materials are available at the site as required by this General Permit.
c. The SWPPP includes the implementation of BMPs that comply with BAT, BCT, and ensure compliance with water quality standards; additional BMPs based on input from the QSP to address numeric action level and numeric effluent limitation exceedances; and additional training needed for the QSP, Legally Responsible Person, or designated persons on-site. d. The SWPPP is available at the site and made available upon request by a federal, State, or municipal inspector. A current copy of the site-specific SWPPP and any site inspection reports required by this General Permit may be kept in electronic format at the site so long as the information requested by a federal, State, or municipal inspector can be made available during an inspection. All maps are legible and available in hard copy at the site.

IV.O.2. The SWPPP shall include:
a. Identification of all pollutants, their sources, and control mechanisms, including sources of sediment associated with all construction activities (e.g., sediment, paint, cement, stucco, cleaners, site erosion); ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 32
b. Pollutant source assessments, including a list of potential pollutant sources and identification of site areas where additional BMPs are necessary to reduce or prevent pollutants in stormwater and authorized non-stormwater discharges, per the following minimum requirements when developing the pollutant source assessment:
i. Consider all potential sources of pollutants, including non-visible pollutants which are known, or should be known to occur on-site including those that:

1. Are used in construction activities;

2. Are stored on-site;

3. Were spilled or released during construction activities or past land use activities and not cleaned up; and

4. Were applied to land as part of past land use activities. ii. Consider all potential sources of pollutants associated with applicable TMDLs listed in Attachment H, and state whether or not sources of those pollutants are present on-site;
iii. Consider the quantity, physical characteristics (e.g., liquid, powder, solid), and locations of each potential pollutant exposed, source handled, produced, stored, recycled, or disposed of on-site; iv. Consider the degree to which pollutants associated with those materials may be exposed to and mobilized by contact with stormwater; and v. Consider the direct and indirect pathways that pollutants may be exposed to stormwater or authorized non-stormwater discharges. This shall include an assessment of past spills or leaks, non-stormwater discharges, and discharges from adjoining areas.
c. Description of site-specific BMPs implemented to reduce or eliminate stormwater pollution, including the following, if applicable:
i. Minimum sediment and erosion control BMPs as outlined in Attachments D and E of this General Permit;
ii. Active treatment systems as included in an Active Treatment System Plan (as required in Section E.1 of Attachment F);
iii. Passive treatment technologies as included in a Passive Treatment Plan (as required in Section D.2 of Attachment G);
iv. BMPs implemented to address applicable TMDL implementation requirements (as required by Attachment H); and
v. Dewatering systems (as required by Attachment J).

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 33
d. Site-specific BMPs initialized immediately to temporarily stabilize an area disturbed by construction where construction activities will not be resumed within 14 days;
e. Identification, elimination, control, or treatment information for all non- stormwater discharges from the site not regulated by this or another NPDES permit;
f. Description of efforts and BMPs used to minimize and control pollutants discharged from equipment and vehicle washing, wheel wash water, and other wash waters. Wash waters must be captured and properly disposed of and/or treated to mitigate impacts to water quality;
g. Description of efforts and BMPs used to minimize exposure of building materials, building products, construction wastes, trash, landscape materials, fertilizers, pesticides, herbicides, detergents, sanitary waste, and other materials present on the site to precipitation and to stormwater; h. Description of spill and leak prevention and response plan including:
i. Procedures that effectively address hazardous and non-hazardous spills in accordance with law;
ii. Spill and leak response equipment and materials to be available on-site, cleaned up immediately, and disposed of properly; and
iii. Personnel are assigned and trained for spill and leak prevention and response.
i. Construction Site Monitoring Program that describes methods and procedures for monitoring discharges in accordance with the applicable Attachment D or E that includes the following:
i. Visual inspection locations, inspection procedures, and follow-up tracking procedures.
ii. Applicable sampling locations, collection, and handling procedures shall include detailed procedures for field analysis, sample collection, storage, preservation, and shipping to the laboratory to ensure consistent quality assurance and control is maintained. iii. A copy of the Chain of Custody form used when handling and shipping samples.
iv. Identification of the analytical methods and related method detection limits (if applicable) for each parameter.
v. Watershed Monitoring Option:

1. If the discharger is part of a qualified regional watershed-based monitoring program approved by the Regional Water Board Executive Officer or their delegate, the discharger may be eligible for relief from the monitoring requirements in the applicable ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 34
Attachment D or E. The Regional Water Board may approve proposals to substitute a qualified watershed-based monitoring program if it determines the program will provide information to determine each discharger’s compliance with the requirements of this General Permit.
j. Title Sheet(s) with:
i. Project name;
ii. Project location (vicinity map);
iii. Preliminary schedule of activities;
iv. Site operating hours (hours when construction activities are occurring); v. Index of attachments;
vi. Contact information for QSD(s), QSP(s), and trained delegates (name, phone numbers, license or certification number); and
vii. Signature of the QSD(s) who prepared the SWPPP.
k. Pre-Earthwork Drawing with:
i. Site and project boundaries;
ii. Areas disturbed during geotechnical or other preconstruction investigation work;
iii. Existing roads and trails;
iv. Drainage areas;
v. Discharge locations;
vi. Existing storm drain system if applicable; and
vii. Proposed locations of storage areas for waste, construction materials, project staging areas, stockpiles, vehicles, equipment and vehicle maintenance, loading/unloading of materials, site access (entrance/exits), fueling, water storage, water transfer for dust control, demolition, and areas of other construction support activities. l. Construction and Earthwork Drawing(s) with:
i. Site layout (grading plans) including roads;
ii. Site and project boundaries;
iii. Drainage areas;
iv. Discharge locations;
v. Sampling locations;
vi. Areas of soil disturbance (temporary or permanent); vii. Proposed active areas of soil disturbance (cut or fill); ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 35
vii. Proposed locations of erosion control BMPs;
ix. Proposed locations of sediment control BMPs;
x. Proposed locations of run-off BMPs;
xi. Temporary and/or permanent run-on conveyance (if applicable); xii. Proposed locations of active treatment systems(s) (if applicable); xiii. Locations of storage areas for waste, construction materials, project staging areas, stockpiles, vehicles, equipment and vehicle maintenance, loading/unloading of materials, site access (entrance/exits), fueling, water storage, water transfer for dust control, demolition, and areas of other construction support activities; and xiv. Site-specific procedures to implement final stabilization BMPs as soon as reasonably practicable.

IV.P. Annual Reporting Requirements
IV.P.1. The discharger shall electronically certify and submit an Annual Report through SMARTS by September 1st for the previous reporting period from July 1st through June 30th if a WDID number is active for at least 90 days within the reporting period.

IV.P.2. The discharger shall retain an electronic copy or hard copy of each Annual Report for a minimum of three years after the date the Annual Report is certified.

IV.P.3. The Annual Report shall consist of the following:
a. The summary of all stormwater sampling and monitoring reports and supporting documents (e.g., laboratory reports);
b. The summary of all corrective actions taken during the compliance year; c. The identification and explanation of any compliance activities (e.g., missed sampling or visual inspections) or corrective actions that were not implemented;
d. The summary of all the General Permit violations;
e. The names of individual(s) who performed the site inspections, sampling, visual inspections, and/or measurements;
f. The date, place, time of site inspections, sampling, visual inspections, and/or measurements, including the amount of precipitation measured in inches; and
g. All visual inspection and sample collection exception records and reports.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 36
V. SITE ROLES AND PERSONNEL
V.A. Discharger Responsibilities
V.A.1. The discharger, as defined in Attachment B, is responsible for all site activity affiliated with General Permit compliance and non-compliance including work done by QSDs, QSPs, and QSP delegates.

V.A.2. The discharger shall ensure that the SWPPP and any required amendments are developed by a QSD. SWPPP changes or amendments shall be uploaded through SMARTS within 30 calendar days.

V.A.3. The discharger shall ensure that all persons responsible for implementing this General Permit’s requirements for a project shall be appropriately licensed or certified in accordance with this General Permit. For example, the discharger shall verify personnel serving as QSD(s) or QSP(s) have an active and current certificate, and engineering and/or geology work performed for the site is conducted by a California licensed professional.

V.A.4. The discharger shall ensure that the correct construction start and end date are:
a. Used for each regulated construction project’s risk determination; b. Listed in SMARTS; and
c. Included on the unique WDID number notification form in a site location viewable by the public or readily available upon request if unable to post publicly.

V.A.5. The discharger shall ensure project data and contact information is current in SMARTS.

V.A.6. If a Legally Responsible Person changes, the discharger shall update the contact information for the Legally Responsible Person in SMARTS.

V.B. Legally Responsible Person
V.B.1. When the discharger is required to sign, certify, and electronically submit any documents required by the General Permit, the State or Regional Water Board, or U.S. EPA, the signatory for the discharger is the Legally Responsible Person and must meet the definition of “Legally Responsible Person” set forth in Attachment B.

V.B.2. The Legally Responsible Person may designate a Duly Authorized Representative, as defined in Attachment B, who may sign, certify, and electronically submit any documents, reports, or information required by this General Permit, the State or Regional Water Boards, or U.S. EPA. The Legally Responsible Person shall update the designation in SMARTS if there are any changes to the Duly Authorized Representative.

V.B.3. The Legally Responsible Person and, if applicable, Duly Authorized Representative shall comply with the electronic signature and certification ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 37
requiremen
ts set forth in Section VI.H when submitting information required by the General Permit.

V.C. Discharger’s Responsibilities for Qualified SWPPP Developer Performance V.C.1. The discharger shall retain a QSD from the beginning of the project through the Notice of Termination approval.

V.C.2. A QSD is required to assess how construction activities will affect sediment transport, erosion, and other discharges of pollutants in stormwater runoff in the SWPPP design and implementation. The QSD is required to revise the SWPPP to address potential problems identified by visual inspections, sampling data, comments from a QSP, or their own site observations.

V.C.3. A QSD is required to include in the SWPPP the name, email, and phone number of all the QSP-trained delegate(s).

V.C.4. The discharger shall ensure that a QSD performs the following on-site visual inspections13:
a. Within 30 days of constr
uction activities commencing on a site;
b. Within 30 days of a discharger replacing the QSD;
c. Twice annually, once August through October and once January through March
;
d. Within 14 calendar days after a numeric action level exceedance; and e. Within the time period requested in writing from Water Board staff.

V.C.5. A QSD may perform the work of a QSP.

V.D. Discharger’s Responsibilities for Qualified SWPPP Practitioner Performance V.D.1. The discharger shall ensure that a QSP reviews work performed by trained delegates including visual inspections, sampling, BMP implementation activities, and other required tasks listed in the SWPPP.

V.D.2. The discharger shall ensure that a QSP performs the following on-site visual inspections14:
a. Once every calendar month;

13 These on-site visual inspection requirements are the minimum required and may be increased by the discharger or a QSD during times of high-risk construction activities, excessive site problems, or other conditions that warrant increased oversight by a QSD.
14 These on-site visual inspection requirements are the minimum requirements and may be increased by the discharger or a QSD during times of high-risk construction

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 38
b. Within 72 hours prior to a forecasted Qualifying Precipitation Event to inspect areas of concern to verify the status of any deficiencies, BMPs, or other identified issues at the site. If extended forecast precipitation data (greater than 72 hours) is available from the National Weather Service, the pre- precipitation event inspection may be done up to 120 hours in advance; c. Within 14 days after a numeric action level exceedance the QSP shall visually inspect the drainage area of exceedance and document any areas of concern; and
d. Prior to the submittal of General Permit Notice of Termination or Change of Information (for acreage changes) of all or part of a site.

V.D.3. The discharger shall ensure that a QSP verifies the following:
a. All BMPs required in the SWPPP are implemented, correctly installed, inspected, and maintained;
b. Track out of construction related material at site entrances and exits is controlled;
c. The SMARTS generated WDID number notification form is in a site location v
iewable by the public or readily available upon request, kept up to date, and the start and end dates are correct and match the dates listed in SMARTS for the project;
d. Sampling protocols for stormwater and non-stormwater discharges are correctly performed as described in the SWPPP by on-site trained personnel delegated by a QSP (including, but not limited to, taking representative samples of the runoff);
e. Contact information including, name, phone number, and email address for the discharger,
Legally Responsible Person, QSD(s), and QSP(s) is correct and updated in SMARTS within 90 days of a change); and
f. Photo documentation of problem areas of erosion, new sediment deposition, unauthorized non-stormwater discharges, and/or failed BMPs is included in the SWPPP and are made available upon a regulatory inspector’s request.

V.E. Discharger Responsibilities for Delegates’ Performance V.E.1. The discharger may authorize a QSP to delegate visual inspections , sampling, and/or SWPPP and BMP implementation activities to others (delegates)
(e.g., superintendent, project manager, foreman, contractor, coworker) that have received training for their respective tasks. A QSP opting to delegate tasks to

activities, excessive site problems, or other conditions that warrant increased oversight of the site.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 39
others shall provide the following training based on the guidelines set by the Construction General Permit Training Team:
a. Foundational training for all delegates regarding stormwater compliance roles and responsibilities, forecast information, and documentation and reporting procedures; and
b. Site-specific training regarding visual inspections, sampling procedures, and/or SWPPP and BMP implementation activities relevant to the delegate’s assigned responsibilities.

V.E.2. The discharger shall ensure the following for QSP-delegate(s ):
a. A QSP has determined the delegate(s) can perform and have a competent understanding of the visual inspection, sampling, and/or SWPPP and BMP implementation tasks prior to fully delegating the responsibility to the individual;
b. The current delegate(s), including name, email, and phone number, are maintained in a training log, uploaded as an attachment to the SWPPP in SMARTS, prior to the delegate performing the delegated function; and
c. The delegate(s) have a system used to record and report issues back to the QSP within 24 hours of when a corrective action is needed.

V.E.3. The delegate cannot perform the QSD and QSP inspections required in Section V.C.4 or Section V.D.2, respectively.

V.F. Becoming a Qualified SWPPP Developer (QSD) or Qualified SWPPP Practitioner (QSP)
V.F.1. All QSDs and QSPs shall have fundamental knowledge of erosion and sedimentation processes, best management practices, and their implementation to control pollutants in stormwater discharges.

V.F.2. California licensed professional engineers or geologists may self-certify their
eligibility to serve as a QSD/QSP via the State Water Board Construction Stormwater Program website.

V.F.2.a. Consistent with Title 16, California Code of Regulations, § 475 Code of Professional Conduct, a California Board for Professional Engineers, Land Surveyors, and Geologists (CBPELSG) licensee shall provide service for a project in a manner that is consistent with the laws, codes, ordinances, and regulations applicable to that project. A CBPELSG licensee shall not misrepresent their scope of authority affiliated with their professional license.

V.F.2.b. The State Water Board expects that a CBPELSG licensee serving a discharger enrolled in this General Permit has thorough knowledge of the conditions and requirements of this General Permit and the required supporting documents and information.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 40
V.F.3. A person can obtain a QSD or QSP certification through the CASQA by completing the following steps:

Step 1: Complete a required prerequisite to take the QSD or QSP training course;
Step 2: Complete the QSD or QSP training course;
Step 3: Pass the QSD or QSP exam; and
Step 4: Register as a QSD or QSP though the CASQA website.

V.F.4. A QSD applicant shall currently possess at least one of the following prerequisites:
a. A California landscape architect registration;
b. A professional hydrologist registration through the American Institute of Hydrology;
c. A Certified Professional in Erosion and Sediment Control (CPESC)TM registration through EnviroCert International, Inc.;
d. A Certified Professional in Stormwater Quality (CPSWQ)TM registration through EnviroCert International, Inc.; or
e. Any prerequisite course approved by the State Water Board’s Division of Water Quality Deputy Director in accordance with Section V.G.

V.F.5. A QSP applicant shall currently possess at least one of the following prerequisites
:
a. A Certified Erosion, Sediment, and Stormwater Inspector (CESSWI) registered through Enviro Cert International, Inc.;
b. A certified inspector of sediment and erosion control registered through Certified Inspector of Sediment and Erosion Control (CISEC) Inc.; c. A Construction Management degree from an accredited 4-year institution that includes coursework that covers the underlying principles of erosion and sediment control and practices of reducing pollution in stormwater; or d. Any prerequisite course approved by the State Water Board’s Division of Water Quality Deputy Director in accordance with Section V.H.

V.F.6. To remain in good standing with their certification, QSDs and QSPs registered through CASQA shall:
a. Complete 6 hours, annually, of continuing education on site assessment techniques, best management practice design and implementation, inspection techniques, or monitoring approaches. This requirement can be fulfilled in whole or in part by continuing education taken to maintain any of the approved underlying prerequisites; and
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 41
b. Complete the online QSD or QSP renewal process every two years, including a review of materials addressing permit implementation updates, clarifications, and experiences as provided by the Construction General Permit Training Team.

V.G. Pre-existing QSP and QSD qualification
V.G.1. A QSD or QSP who maintained a valid certification as of the effective date of this General Permit shall remain in good standing.

V.G.1.a. Existing QSDs and QSPs certified through CASQA shall, prior to the expiration date of their current certificate, certify that they have maintained a valid underlying certification and complete the recertification review or refresher training through CASQA’s renewal process.

V.G.1.b. Existing QSD/QSPs who have self-certified with the State Water Board that they are a California licensed professional engineer or California licensed professional geologist shall complete the recertification process through the State Water Board Construction Stormwater Program website and complete self-directed training required by the State Water Board before

September 1, 2024.

V.H. QSP and QSD Prerequisite Course Qualification
V.H.1. The State W ater Board’s Division of Water Quality Deputy Director may approve the qualification of additional prerequisite courses for QSD and QSP certification.

V.H.2. Individuals may recommend additional prerequisite courses by emailing the Stormwater Help Desk ([email protected]). The course curriculum shall meet an acceptable level of training and require continuing education to maintain their certification.

V.H.3. The C onstruction General Permit Training Team will review any recommended prerequisite courses and provide feedback for the State Water Board Division of Water Quality Deputy Director’s consideration. If approved, the course will be listed on the State Water Board’s Construction Stormwater Program website (https://www.waterboards.ca.gov/water_issues/programs/stormwater/constructio n.html) as an approved prerequisite course.

V.I. Water Board Rescission of a QSP or QSD Certification V.I.1. The State Water Board Executive Director or a Regional Water Board Executive Officer may:
a. Suspend any QSD or QSP certification and require that additional training be completed as a condition of re-instatement if the Executive Director or Executive Officer finds, in writing, that the QSD or QSP in the course of acting as a QSD or QSP at one or more site(s) lacked adequate knowledge or training to perform duties required by the General Permit; and/or ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 42
b. Rescind any QSD or QSP certification if, after providing notice and an opportunity to be heard, the Executive Director or Executive Officer finds, in writing, that the QSD or QSP has in the course of acting as a QSD or QSP at one or more site(s), (1) willfully or negligently caused or allowed a violation
of this General Permit; (2) submitted false or misleading information to the State Water Board or any Regional Water Board, (3) used fraud or deception; or (4) failed to use reasonable care and good judgment.

V.I.2. An individual whose QSD or QSP certification has been rescinded may request the State
Water Board to review the rescission. Any request for review must be received by the State Water Board no later than 30 days after the date that the individual received written notice of the rescission.

VI. STANDARD PROVISIONS
VI.A. Duty to Comply

VI.A.1. The discharger shall comply with all General Permit conditions and requirements. Any General Permit non-compliance constitutes a violation of the Clean Water Act and the Porter-Cologne Water Quality Control Act and is grounds for enforcement action and/or removal of General Permit coverage.

VI.A.2. The discharger shall comply with effluent standards or prohibitions established under Clean Water Act § 307(a) for toxic pollutants within the time provided in the regulations that establish these standards or prohibitions.

VI.B. Need to Halt or Reduce Activity Not a Defense
A discharger’s
claim that it would have been necessary to halt or reduce the permitted activity in order to maintain compliance with this General Permit shall not be a defense in an enforcement action.

VI.C. Duty to Mitigate
The discharger shall take all responsible steps to minimize or prevent any discharge that has a reasonable likelihood of adversely affecting human health or the environment in violation of this General Permit, which includes ceasing discharge as necessary.

VI.D. Proper Operation and Maintenance
VI.D.1. The discharger shall at all times properly install, operate, and maintain any treatment and control facilities, systems, related appurtenances, and backup or auxiliary systems (treatment control systems) which are installed or used by the discharger to achieve compliance with this General Permit’s conditions.

VI.D.2. The discharger shall include adequate laboratory controls and appropriate quality assurance procedures for all treatment control systems.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PA GE | 43
VI.E. Property Rights
This General Permit does not: (1) convey any property rights of any sort or any exclusive privileges, (2) authorize any injury to private property or any invasion of personal rights, (3) or authorize any infringement of federal, state, or local laws or regulations.

VI.F. Duty to Maintain Records and Provide Information
VI.F.1. The discharger shall maintain a paper or electronic copy of all required records and reports, including but not limited to,
a copy of this General Permit and all its
attachments and Fact Sheet, for three years from the date generated or date submitted whichever is later.

VI.F.2. The discharger shall furnish the Water Boards or U.S. EPA, within a reasonable time, any requested information to determine compliance with this General Permit. The discharger shall also furnish, upon request, copies of records that are required to be kept by this General Permit.

VI.G. Inspection and Entry
VI.G.1. The discharger shall allow staff of the Water Boards, U.S. EPA, and/or an authorized representative of the municipal separate storm sewer system receiving the discharge to:
a. Enter the site premises during a regulated construction activity and/or at the location where compliance records are maintained in accordance with this General Permit;
b. Access and copy
any compliance records maintained in accordance with
this General Permit;
c. Inspect the complete project and site, including any off-site staging areas or material storage areas, and the erosion/sediment controls; d. Sample, monitor, or install automated sampling equipment to ensure General Permit monitoring compliance; and
e. Conduct bioassessment monitoring (if required by a Regional Board water quality control plan), receiving water monitoring, and/or evaluate the performance of BMPs.

VI.H. Electronic Signature and Certification Requirements VI.H.1. All documents submitted to the Water Boards (including, but not limited to, Permit Registration Documents, Annual Reports, monitoring records, and ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 44
Notices of Termination) are required to be certified by the Legally Responsible Person15 or a Duly Authorized Representative16 through SMARTS.

VI.H.2. All documents (e.g., designs, plans, reports) that require engineering or geologic evaluations and judgments must be prepared by, or under the direction of, appropriately licensed professionals in the State of California. The licensee must sign and provide their registration number or stamp on the documents to be submitted and certified by the Legally Responsible Person or Duly Authorized Representative.

VI.H.3. Any person signing documents under Section VI.H shall make the following certification:

“I certify under penalty of law that this document and all attachments were prepared under my direction or supervision in accordance with a system designed to assure that qualified personnel properly gather and evaluate the information submitted. Based on my inquiry of the person or persons who manage the system, or those persons directly responsible for gathering the information, the information submitted is, to the best of my knowledge and belief, true, accurate, and complete. I am aware that there are significant penalties for submitting false information, including the possibility of fine and imprisonment for knowing violations. I am also aware that my user ID and password constitute my electronic signature and any information I indicate I am electronically certifying contains my signature. I understand that my electronic signature is the legal equivalent of my handwritten signature. My signature on this form certifies that my electronic signature is for my own use, that I will keep it confidential, and that I will not delegate or share it with any other person.

Should I wish to delegate such authority, I will do so formally in writing and electronically notify the State Water Board using SMARTS of such delegation within 10 days of the delegation. I further certify that I will protect my electronic signature from unauthorized use, and that I will contact the State Water Board, within two business days of discovery, if I suspect that my electronic signature has been lost, stolen, or otherwise compromised.”
VI.H.4. Clean Water Act § 309(c)(4) provides that any person who knowingly makes any false material statement, representation, or certification in any record or other document submitted or required to be maintained under this General Permit, including reports of compliance or non-compliance shall upon conviction, be penalized with a monetary fine of up to $10,000 or by imprisonment for not more than two years, or both.

15 Defined in this General Permit, Attachment B (Glossary) 16 Defined in this General Permit, Attachment B (Glossary) ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PA GE | 45
VI.I. Anticipated Noncompliance
The discharger shall provide advance notice, in writing, to the applicable Regional Water Board and local stormwater management agency of any planned changes in site construction activities that may result in non-compliance with this General Permit.

VI.J. Reporting of Contaminated Soils
The discharger shall have soils sampled and tested to ensure proper handling and public safety measures are implemented when soil contamination is found or suspected, and a responsible party is not identified, or the responsible party fails to promptly take the appropriate action. The discharger shall notify the appropriate local, state (including the Regional Water Board), and federal agency(ies) when contaminated soil is found at a site.

VI.K. Bypass
VI.K.1. Bypass 17 is prohibited unless the discharger demonstrates one or more of the following conditions:
a. In accordance with the bypass requirements for active treatment systems in Attachment F; or
b. Bypass was unavoidable to prevent loss of life, personal injury, or severe property damage18; or
c. There were no feasible alternatives to bypass, such as the use of auxiliary treatment facilities, retention of untreated waste, or maintenance during normal periods of equipment downtime. This condition is not satisfied if adequate back-up equipment should have been installed in the exercise of reasonable engineering judgment to prevent a bypass that could occur during normal periods of equipment downtime or preventative maintenance; or
d. The discharger allowed a bypass to occur that does not cause the exceedance of an effluent limitation(s), due to essential maintenance to assure efficient operation. In such a case, the above bypass conditions are not applicable; and

17 The intentional diversion of waste streams from any portion of a treatment facility or system.
18 Severe property damage means substantial physical damage to property, damage to the treatment facilities that causes them to become inoperable, or substantial and permanent loss of natural resources that can reasonably be expected to occur in the absence of a bypass. Severe property damage does not mean economic loss caused by delays in production.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PA GE | 46
e. The discharger submitted a notice to the Regional Water Board, at least 14 calendar days in advance of the need for a bypass except where advance notice was not possible due to an emergency situation where the bypass was unavoidable to prevent loss of life, personal injury or severe property damage. If t
he discharger was unable to notify the Regional Water Board in advance of a bypass the discharger shall submit written notification to the Regional Water Board within 14 days after the bypass occurs.

VI.L. Upset
VI.L.1. To establish an affirmative defense of an upset, 19 a discharger must demonstrate the following through properly signed, contemporaneous operating logs or other relevant evidence:
a. The non-compliance discharge location;
b. The cause(s) of the upset;
c. The treatment facility was properly operated and maintained at the time of the upset;
d. The discharger submitted notice of the upset as required; and e. Any required remedial measures were implemented as soon as feasibly possible.

VI.L.2. An administrative determination made before an action of noncompliance occurs is not a final administrative action subject to review.

VI.L.3. In an enforcement proceeding, the discharger seeking to establish the occurrence of an upset has the burden of proof.

VI.M. Oil and Hazardous Substance Liability
This General Permit, or parts of this General Permit (including, but not limited to, the findings, requirements, conditions, and provisions) shall not be construed to preclude the institution of any legal action or relieve the discharger from any responsibilities, liabilities, or penalties to which the discharger is or may be subject to under Clean Water Act § 311.

19 An exceptional incident in which there is unintentional and temporary non- compliance with technology-based numeric effluent limitations because of factors beyond the reasonable control of the discharger. An upset event does not include a large precipitation event, wind event, or other natural weather-related force of nature.

An upset does not include non-compliance to the extent caused by operational error, improperly designed treatment facilities, inadequate treatment facilities, lack of preventative maintenance, or careless or improper operation.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 47
VI.N. Severability
The provisions of this General Permit are severable; if any provision of this General Permit or the application of any provision of this General Permit to any circumstance is held invalid, the application of such provision to other circumstances, and the remainder of this General Permit, shall not be affected thereby.

VI.O. Reopener Clause
VI.O.1. This General Permit may be modified, revoked and reissued, or terminated for cause due to promulgation of amended regulations, receipt of U.S. EPA guidance concerning regulated activities, judicial decision, or in accordance with 40 Code of Federal Regulations §§ 122.62, 122.63, 122.64, and 124.5.

VI.O.2. The submittal of a request by the discharger for a General Permit modification, revocation and reissuance, or termination, notification of planned changes, or anticipated non-compliance does not annul any General Permit condition.

VI.O.3 This General Permit shall be modified or revoked and reissued to conform if any applicable toxic effluent standard or prohibition (including any schedule of compliance specified in such effluent standard or prohibition) promulgated under Clean Water Act §307(a) for a toxic pollutant which is present in the discharge and the standard or prohibition is more stringent than any pollutant limitation in this General Permit. The Water Boards shall provide the public and dischargers notice of the action.

VI.O.4 This General Permit may be reopened before March 23, 2032 to revise the requirements implementing the Los Angeles and Long Beach Harbor Waters TMDL for copper, lead, and zinc, for dischargers that discharge to the Dominguez Channel or the Torrance Lateral Channel. State Water Board staff will work with interested stakeholders to develop a plan to collect additional data related to the forthcoming implementation of the 100 mg/L TSS numeric effluent limitation, including the soil screening investigation, and report to the State Water Board via the Executive Director report no later than September 1, 2024.

The State Water Board will evaluate whether the additional data and other available information warrants revising the requirements implementing the Los Angeles and Long Beach Harbor Waters TMDL for copper, lead, and zinc at a publicly noticed Board meeting no later than August 31, 2028.

VI.O.5 This General Permit may be reopened to revise the requirements implementing the Los Angeles Lakes TMDL for chlordane, DDT, dieldrin, and PCBs that discharge to Peck Road Park Lake, Echo Park Lake or Puddingstone Reservoir.

State Water Board staff will work with interested stakeholders to develop a plan to collect additional data related to the implementation of the 100 mg/L TSS numeric effluent limitation, including the soil screening investigation, and report to the State Water Board via the Executive Director report no later than September 1, 2023. Upon completion of the work required by the plan, the State Water Board will evaluate whether the additional data and other available ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 48
information warrants revising the requirements implementing the Los Angeles Lakes TMDL for chlordane, DDT, dieldrin, and PCBs at a publicly noticed Board meeting.

VI.P. Penalties for Violations of General Permit Conditions VI.P.1. Clean Water Act § 309 provides significant penalties for any person who violates a permit condition implementing Clean Water Action §§ 301, 302, 306, 307, 308, 318, or 405 or any permit condition or limitation implementing any such section in a permit issued under § 402. Any person who violates any permit condition of this General Permit is subject to a civil penalty not to exceed $37,50020 per calendar day of such violation, as well as any other appropriate sanction provided by §309 of the Clean Water Act.

VI.P.2. Clean Water Act § 309(c)(4) provides that any person who knowingly makes any false material statement, representation, or certification in any record or other document submitted or required to be maintained by this General Permit, including reports of compliance or non-compliance shall upon conviction, be punished by a fine of not more than $10,000 or by imprisonment for not more than two years or both.

VI.P.3. The Porter-Cologne Water Quality Control Act provides specific administrative, civil, and criminal penalties, which in some cases are greater than those under the Clean Water Act.

VI.Q. Water Quality Based Corrective Actions 21
VI.Q.1. By the end of each reporting year, if the discharger’s construction stormwater and/or non
-stormwater discharges contain pollutants that are in violation of Receiving Water Limitations (Section IV.D) or in the event that a Responsible Discharger’s discharge exceeds an applicable numeric effluent limitation in Attachment H, the discharger shall:
a. Conduct a site assessment to identify pollutant source(s) within the site that are associated with construction activity and whether the BMPs described in the SWPPP have been properly implemented;
b. Evaluate the site’s SWPPP and its implementation to determine whether additional BMPs or SWPPP implementation measures are necessary to reduce or prevent pollutants in all regulated discharges to comply with the Receiving Water Limitations (Section IV.D) or applicable numeric effluent limitations in Attachment H; and

20 May be further adjusted in accordance with the Federal Civil Penalties Inflation Adjustment Act.
21 Terms including, but not limited to, Responsible Dischargers, numeric effluent limitations and exceedances are defined in Attachment B of this General Permit.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PAGE | 49
c. Certify and submit, through SMARTS, documentation based upon the above site assessment and SWPPP evaluation that:
i. Additional BMPs and/or SWPPP implementation measures have been identified and included in the SWPPP to comply with the Receiving Water Limitations (Section IV.D) or applicable numeric effluent limitations in Attachment H; or
ii. No additional BMPs
or SWPPP implementation measures are required
to reduce or prevent pollutants in all regulated discharges to comply with the Receiving Water Limitations (Section IV.D) or applicable numeric effluent limitations in Attachment H.

VI.Q.2. The Regional Water Board or its delegate may require revisions of the discharger’s water quality-based corrective actions and/or request additional supporting documentation.

VI.R. Continuation of Expired General Permit
This General Permit continues in force and effect until the effective date of a new General Permit adopted the State Water Board or the State Water Board rescinds this General Permit.

VII. REGIONAL WATER BOARD AUTHORITIES
VII.A. Regional Water Boards (as defined in Attachment B) may terminate General Permit coverage upon determination that a discharger has failed to comply with General Permit requirements. The Regional Water Boards may also terminate General Permit coverage upon determination that the subject discharges must be regulated through a separate Regional Water Board-issued NPDES permit.

VII.B. Regional Water Boards may require a discharger to comply with additional monitoring and reporting requirements, including but not limited to, increasing sampling
frequency, requiring analysis of additional parameters, increasing the frequency of inspections by the Qualified SWPPP Developer and Qualified SWPPP Practitioner, or implementation of recommendations by the Qualified SWPPP Developer and Qualified SWPPP Practitioner, pursuant to California Water Code § 13383.

VII.C. All Regional Water Board actions that modify requirements for compliance, pursuant to California Water Code §13383, with this General Permit shall be provided to the discharger in writing and submitted through SMARTS.

VII.D. Regional Water Boards may require dischargers to retain records required by this General Permit for more than the three years.

VII.E. Regional Water Boards may obtain site-specific data, records, or documentation demonstrating one or more numeric action level exceedances occurred at a site and may direct the discharger to revise their SWPPP and/or BMPs to address the exceedance.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ORDER WQ 2022-0057-DWQ PA GE | 50
VII.F. Consistent with California Water Code §§13350(a) and/or 13376, Regional Water Boards finding a discharger in violation of a prohibition or requirement in this General Permit with the potential to discharge pollutants into the waters of the United States, may require a discharger to revise and re-submit the SWPPP, other required documents and/or implement additional BMPs to address site- specific conditions.

VII.G. Consistent with 40 Code of Federal Regulations §§ 122.26(a)(9)(i)(D) and 122.26(a)(9)(i)(C), a Regional Water Board may require any discharge of stormwater and non-stormwater from construction activity that is not regulated by this General Permit, and that may cause or contribute to an exceedance of a water quality standard, to obtain General Permit coverage.

VII.H. A Regional Water Board has the authority to require a Risk Level determination to be reassessed for a site currently regulated under this General Permit, or with an active waiver, as deemed necessary, including but not limited to the following circumstances:

1. The discharger has a demonstrated history of General Permit non-compliance with this General Permit or its predecessors;

2. The subject construction site poses a significant risk of causing or contributing to an exceedance of a water quality standard without the implementation of the additional Risk Level 2 or 3 requirements; or

3. The Regional Water Board staff have documented that the discharger Risk Level for the subject site is calculated incorrectly.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-1

FACT SHEET

NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM (NPDES)

GENERAL PERMIT FOR STORMWATER DISCHARGES ASSOCIATED

WITH CONSTRUCTION AND LAND DISTURBANCE ACTIVITIES
(GENERAL PERMIT)
Table of Contents
FACT SHEET .................................................................................................................. 1 I. BACKGROUND .............................................................................................. 5 I.A. History ............................................................................................................. 5 I.B. Legal Challenges and Court Decisions ........................................................... 6 I.C. Healthy Soils and Recycled Water ................................................................ 12 I.D. Blue Ribbon Panel of Experts (Panel) ........................................................... 13 I.E. Summary of Significant Changes in This General Permit.............................. 15 I.F. Cost Considerations ...................................................................................... 20 I.G. Incorporation of Total Maximum Daily Load (TMDL) Requirements and Cost 23 I.H. Rationale ....................................................................................................... 42 I.I. Regional Water Board Authorities ................................................................. 62 I.J. Construction Activities Covered .................................................................... 63 I.K. Construction Activities Not Covered .............................................................. 68 I.L. Obtaining and Modifying General Permit Coverage ...................................... 70 I.M. Notice of Termination Final Stabilization ....................................................... 73 I.N. Discharge Prohibitions .................................................................................. 73 I.O. Technology and Water Quality Based Effluent Limitations for All Types of Discharges .................................................................................................... 74 I.P. Training Qualifications and Requirements..................................................... 84 I.Q. Sampling, Monitoring, Reporting, and Record Keeping for Linear Underground and Overhead Projects and Traditional Construction Monitoring Requirements ................................................................................................ 85 I.R. Risk Determination ........................................................................................ 96 I.S. Active Treatment System Requirements ..................................................... 107 I.T. Passive Treatment Requirements ............................................................... 110 I.U. Post-Construction Requirements ................................................................ 112 I.V. Stormwater Pollution Prevention Plans (SWPPPs) ..................................... 120 ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-2
I.W. Total Maximum Daily Loads (TMDLs) ......................................................... 122

FIGURES AND TABLES
Figure 1 – Suite of Precipitation Events ...................................................................... 113 Figure 2 – Schematic of the Lane Relationship........................................................... 115 Figure 3 – Channel Changes Associated with Urbanization........................................ 116 Table 1 – University of New Hampshire Stormwater Center Select BMP Maintenance Costs and Hours ........................................................................................................... 36 Table 2 – Effective BMP Examples for TMDL Pollutant Categories .............................. 41 Table 3 – Regional Water Board Basin Plans, Water Quality Objectives for Turbidity .. 78 Table 4 – Results of Ecoregion Analysis....................................................................... 79 Table 5 – Administrative Civil Liabilities (ACL) Sampling Data taken by Regional Water Board Staff .................................................................................................................... 79 Table 6 – Subdata Set Turbidity for Point of Stormwater Runoff Discharge at Northstar Village ........................................................................................................................... 80 Table 7 – Required Monitoring Elements for Risk Levels.............................................. 90 Table 8 – Stormwater Effluent Monitoring Requirements by Risk Level........................ 90 Table 9 – Require Monitoring Elements for Linear Underground and Overhead Project Types ............................................................................................................................ 91 Table 10 – Receiving Water Monitoring Requirements ................................................. 94 Table 11 – Los Angeles Regional Water Quality Control Board Bacteria Water Quality Objectives ................................................................................................................... 128 Table 12 – Calleguas Creek Interim Dry-Weather Waste Load Allocations ................ 131 Table 13 – Calleguas Creek Final Dry-Weather Waste Load Allocations.................... 131 Table 14 – Upper Santa Clara River Chloride Waste Load Allocation Translation...... 134 Table 15 – All Streams in Pajaro River Basin – Un-Ionized Ammonia Waste Load Allocation Translation.................................................................................................. 137 Table 16 – All Streams in Pajaro River Basin (with MUN Beneficial Uses) Waste Load Allocation Translation.................................................................................................. 138 Table 17 – Pajaro River (All Reaches) and Pajaro River Estuary Waste Load Allocation Translation .................................................................................................................. 138 Table 18 – Corralitos Creek and Salsipuedes Creek (All Reaches) Waste Load Allocation Translation.................................................................................................. 138 Table 19 – Beach Road Ditch and McGowan Ditch Waste Load Allocation Translation .................................................................................................................................... 138 Table 20 – Llagas Creek (Downstream of Cheseboro Reservoir), Carnadero Creek, Uvas Creek, and Furlong Creek (All Reaches) Waste Load Allocation Translation .... 139 Table 21 – San Juan Creek and West Branch of San Juan Creek (All Reaches) Waste Load Allocation Translation ......................................................................................... 139 ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-3
Table 22 – Tequisquita Slough Waste Load Allocation Translation ............................ 139 Table 23 – Watsonville Slough, Harkins Slough, Gallighan Slough, and Struve Slough (All Reaches) Waste Load Allocation Translations...................................................... 139 Table 24 – Millers Canal (All Reaches) Waste Load Allocation Translations .............. 140 Table 25 – Total Nitrogen Waste Load Allocation Translation..................................... 143 Table 26 – Total Phosphorus Waste Load Allocation Translation ............................... 143 Table 27 – Los Angeles River above LA-Glendale WRP Waste Load Allocation Translation .................................................................................................................. 146 Table 28 – Los Angeles River below LA-Glendale WRP Waste Load Allocation Translation .................................................................................................................. 146 Table 29 – Los Angeles River Tributaries Waste Load Allocation Translation ............ 146 Table 30 – Los Angeles River Tributaries Waste Load Allocation Translation ............ 146 Table 31 – Machado Lake Nutrient Waste Load Allocations Translation .................... 148 Table 32 – Santa Clara River Reach 3 Ammonia as Nitrogen Waste Load Allocation Translation .................................................................................................................. 149 Table 33 – Santa Clara River Reach 7 Ammonia as Nitrogen Waste Load Allocation Translation .................................................................................................................. 149 Table 34 – Ventura River Algae Dry-Weather Waste Load Allocations....................... 152 Table 35 – Ventura River Algae Wet-Weather Waste Load Allocations...................... 152 Table 36 – Sediment Load Allocations for the Lower Eel River Watershed and its Tributaries ................................................................................................................... 159 Table 37 – Sediment Load Allocations for the Middle Fork Eel River Watershed and its Tributaries (tons/mi2/yr)............................................................................................... 160 Table 38 – Sediment Load Allocations for the Upper Main Eel River Watershed and its Tributaries ................................................................................................................... 164 Table 39 – Sediment Load Allocations for the Mad River Watershed ......................... 167 Table 40 – TMDL and Allocations by Source Category for Upper Area (tons/mi2/year) .................................................................................................................................... 173 Table 41 – TMDL and Allocations by Source Category for Upper Middle Area (tons/mi2/year)............................................................................................................. 173 Table 42 – TMDL and Allocations by Source Category for Lower Middle Area (tons/mi2/year)............................................................................................................. 174 Table 43 – TMDL and Allocations by Source Category for Lower Area (tons/mi2/year) .................................................................................................................................... 174 Table 44 – Other Urban and Rural Land Load Allocations for San Lorenzo River Sediment TMDL .......................................................................................................... 180 Table 45 – Ballona Creek and Sepulveda Channel Waste Load Allocations .............. 190 Table 46 – Ballona Creek Estuary Waste Load Allocations ........................................ 192 Table 47 – Calleguas Creek, Conejo Creek, and Revolon Slough Interim Wet-Weather Waste Load Allocations............................................................................................... 194 Table 48 – Calleguas Creek, Conejo Creek, and Revolon Slough Interim Wet-Weather Waste Load Allocations............................................................................................... 195 ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-4
Table 49 – Interim Limits and Final Waste Load Allocations for Mercury in Suspended Sediment for Calleguas Creek and Revolon Slough ................................................... 196 Table 50 – Interim Sediment Waste Load Allocations (ng/g) for Stormwater Permittees .................................................................................................................................... 198 Table 51 – Final Sediment Waste Load Allocations (ng/g) for Stormwater Permittees199 Table 52 – Colorado Lagoon Waste Load Allocations................................................. 201 Table 53 – Peck Road Park Lake Toxics Waste Load Allocation................................ 202 Table 54 – Echo Park Lake Toxics Waste Load Allocation ......................................... 203 Table 55 – Puddingstone Reservoir Toxics Waste Load Allocation ............................ 203 Table 56 – Dominguez Channel and Torrance Lateral Interim Waste Load Allocation Translation .................................................................................................................. 205 Table 57 – Dominguez Channel and Torrance Lateral Final Waste Load Allocation .. 206 Table 58 – Dominguez Channel Estuary and Greater Harbor Waters Interim Sediment Waste Load Allocations in mg/kg sediment................................................................. 208 Table 59 – Dominguez Channel Estuary Final Water Column Waste Load Allocation Translations................................................................................................................. 209 Table 60 – Greater Harbor Final Water Column Waste Load Allocation Translations. 209 Table 61 – Dominguez Channel Estuary, Consolidated Slip and Fish Harbor Final Sediment Waste Load Allocations............................................................................... 210 Table 62 – Los Angeles River Waste Load Allocations Translation for Total Recoverable Metals.......................................................................................................................... 214 Table 63 – Los Cerritos Mass-based Waste Load Allocations .................................... 216 Table 64 – Los Cerritos Channel Waste Load Allocations (Concentration-based, Total Recoverable)............................................................................................................... 217 Table 65 – Machado Lake Toxics Waste Load Allocations ......................................... 219 Table 66 – Marina del Rey Toxics Metals Waste Load Allocations ............................. 221 Table 67 – Marina del Rey Toxics OC Pesticides Waste Load Allocations................. 221 Table 68 – Oxnard Drain No. 3 Waste Load Allocations ............................................. 223 Table 69 – San Gabriel River Reach 2 Watershed Waste Load Allocation................. 225 Table 70 – Coyote Creek Watershed Waste Load Allocations.................................... 225 Table 71 – San Gabriel River Reach 2 Watershed Waste Load Allocation Translation (concentration-based, total recoverable)..................................................................... 226 Table 72 – Coyote Creek Watershed Waste Load Allocations (concentration-based, total recoverable) ........................................................................................................ 226 Table 73 – Santa Monica Bay Toxics Waste Load Allocations.................................... 228 Table 74 – San Diego Creek Watershed Waste Load Allocation Translation.............. 232 Table 75 – Upper Newport Bay, Lower Newport Bay and Bay Segments, and Rhine Channel Metals Waste Load Allocation Translation .................................................... 235 Table 76 – San Diego Creek, Upper Newport Bay and Lower Newport Bay Organochlorine Compounds Waste Load Allocations ................................................. 235 Table 77 – Chollas Creek Metals Waste Load Allocations.......................................... 238 Table 78 – Chollas Creek Dissolved Metals Waste Load Allocation Translation......... 239 ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-5
I. BACKGROUND
I.A. History
The Federal Water Pollution Control Act (also referred to as the Clean Water Act (CWA)) was amended in 1972 to provide that the discharge of pollutants to waters of the United States from any point source is unlawful unless the discharge complies with a National Pollutant Discharge Elimination System (NPDES) permit. The 1987 amendments to the Clean Water Act added § 402(p), which establishes a framework for regulating municipal and industrial stormwater discharges under the NPDES Program. The United States Environmental Protection Agency (U.S. EPA) published final regulations on November 16, 1990, establishing stormwater permit application requirements for specified categories of industries. The regulations provide that discharges of stormwater to waters of the United States from construction projects that encompass five or more acres of soil disturbance are effectively prohibited unless the discharge complies with a NPDES permit. Regulations (Phase II Rule) that became final on December 8, 1999, lowered the permitting threshold from five acres to one acre.

The State Water Resources Control Board (State Water Board) has elected to adopt only one statewide general permit at this time that will apply to most stormwater discharges associated with construction and land disturbance activity, although federal regulations allow two permitting options for stormwater discharges (individual permits and general permits).

The State Water Board reissued the Construction General Permit for Stormwater Discharges on September 2, 2009 (Water Quality Order 2009-0009-DWQ). The State Water Board adopted Order 2010-0014-DWQ on November 16, 2010, to clarify the signatory requirements. The State Water Board adopted Order 2012- 0006-DWQ on July 17, 2012, to remove numeric effluent limitations outside of the use of active treatment systems. Water Quality Order 2009-0009-DWQ and the subsequent amendments are collectively referred to as the previous permit.

The General Permit accompanying this Fact Sheet regulates stormwater runoff from construction sites. Regulating many stormwater discharges under one general permit greatly reduces the administrative burden associated with permitting individual stormwater discharges. To obtain coverage under this General Permit, dischargers shall electronically certify and submit the Permit Registration Documents, which includes a Notice of Intent, Stormwater Pollution Prevention Plan (SWPPP), and other compliance related documents required by this General Permit and submit the appropriate permit fee to the State Water Board. The Regional Water Quality Control Boards (Regional Water Boards) may issue general permits or individual permits containing more specific provisions as the stormwater program develops and if this occurs, this General Permit will no longer regulate those dischargers.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-6
I.B. Legal Challenges and Court Decisions
I.B.1. Early Court Decisions
The U.S. EPA promulgated regulations exempting most stormwater discharges from the NPDES permit requirements shortly after the passage of the Clean Water Act. (See 40 Code of Federal Regulations § 125.4 (1975); see also Natural Resources Defense Council v. Costle (D.C. Cir. 1977) 568 F.2d 1369, 1372 (Costle); Defenders of Wildlife v. Browner (9th Cir. 1999) 191 F.3d 1159, 1163 (Defenders of Wildlife).) The District of Columbia Court of Appeals invalidated the regulation, holding that the U.S. EPA “does not have authority to exempt categories of point sources from the permit requirements of [CWA] § 402.” (Costle, 568 F.2d at 1377) when environmental groups challenged this exemption in federal court. The Costle court rejected the U.S. EPA argument that effluent-based storm sewer regulation was administratively infeasible because of the variable nature of stormwater pollution and the number of affected storm sewers throughout the country. (Id. at 1377-82.) Although the court acknowledged the practical problems relating to storm sewer regulation, the court found the U.S. EPA had the flexibility under the Clean Water Act to design regulations that would overcome these problems. (Id. at 1379-83.) In particular, the court pointed to general permits and permits based on requiring best management practices (BMPs).

During the next 15 years, the U.S. EPA made numerous attempts to reconcile the statutory requirement of point source regulation with the practical problem of regulating possibly millions of diverse point source discharges of stormwater. (See Defenders of Wildlife, 191 F.3d at 1163; see also Gallagher, Clean Water Act in Environmental Law Handbook (Sullivan, edit., 2003) p. 300 (Environmental Law Handbook); Eisen, Toward a Sustainable Urbanism: Lessons from Federal Regulation of Urban Stormwater Runoff (1995) 48 Wash. U.J. Urb. & Contemp.

L.1, 40-41 [Regulation of Urban Stormwater Runoff].)
Congress amended the Clean Water Act in 1987 to require NPDES permits for stormwater discharges. (See Clean Water Act § 402(p), 33 USC § 1342(p); Defenders of Wildlife, 191 F.3d at 1163; Natural Resources Defense Council v.

U.S. EPA (9th Cir. 1992) 966 F.2d 1292, 1296.) Congress distinguished between industrial and municipal stormwater discharges in these amendments enacted as part of the Water Quality Act of 1987. Congress provided that NPDES permits regarding industrial stormwater discharges "shall meet all applicable provisions of this section and section 1311 [requiring the U.S. EPA to establish effluent limitations under specific timetables]." (CWA § 402(p)(3)(A), 33 USC § 1342(p)(3)(A); see also Defenders of Wildlife, 191 F.3d at 1163-64.) U.S. EPA adopted regulations in 1990 specifying the activities that were considered to be “industrial” and thus required discharges of stormwater associated with those activities to obtain coverage under NPDES permits. (55 Fed.

Reg. 47,990 (1990); 40 Code of Federal Regulations § 122.26(b)(14).) ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-7
Construction activities were originally deemed a subset of the industrial category. (40 Code of Federal Regulations § 122.26(b)(14)(x).) In 1999, U.S. EPA issued regulations for “Phase II” of stormwater regulation, which required most small construction sites (1-5 acres) to be regulated under the NPDES program. (64 Fed.

Reg. 68,722; 40 Code of Federal Regulations § 122.26(b)(15)(i).) I.B.2. Court Decisions on Public Participation
Two federal court opinions have vacated U.S. EPA’s rules that denied meaningful public review of NPDES permit conditions. The Ninth Circuit Court of Appeals on January 14, 2003, held that certain aspects of U.S. EPA’s Phase II regulations governing MS4s were invalid primarily because the general permit did not contain express requirements for public participation. (Environmental Defense Center v.

U.S. EPA (9th Cir. 2003) 344 F.3d 832.) Specifically, the court determined that applications for general permit coverage (including the Notice of Intent and Stormwater Management Program) must be made available to the public, the applications must be reviewed and determined to meet the applicable standard by the permitting authority before coverage commences, and there must be a process to accommodate public hearings. (Id. at 852-54.) Similarly, the Second Circuit Court of Appeals on February 28, 2005, held that the U.S. EPA's confined animal feeding operation rule violated the Clean Water Act because it allowed dischargers to write their own nutrient management plans without public review. (Waterkeeper Alliance v. U.S. EPA (2d Cir. 2005) 399 F.3d 486.) Although neither decision involved the issuance of construction stormwater permits, this General Permit addresses the courts’ rulings where feasible.1
The Clean Water Act and the U.S. EPA regulations provide states with the discretion to formulate permit terms, including specifying best management practices (BMPs), to achieve strict compliance with federal technology-based and water quality-based standards. (Natural Resources Defense Council v. U.S. EPA (9th Cir. 1992) 966 F.2d 1292, 1308.) Accordingly, this General Permit has developed specific BMPs, numeric action levels, and Total Maximum Daily Load (TMDL)-derived numeric action level and numeric effluent limitations in order to 1 In Texas Independent Producers and Royalty Owners Assn. v. U.S. EPA (7th Cir. 2005) 410 F.3d 964, the Seventh Circuit Court of Appeals held that the U.S. EPA’s Construction General Permit was not required to provide the public with the opportunity for a public hearing on the Notice of Intent or Stormwater Pollution Prevention Plan. The Seventh Circuit briefly discussed why it agreed with the Ninth Circuit’s dissent in Environmental Defense Center, but generally did not discuss the substantive holdings in Environmental Defense Center and Waterkeeper Alliance, because neither court addressed the initial question of whether the plaintiffs had standing to challenge the permits at issue. However, notwithstanding the Seventh Circuit’s decision, it is not binding or controlling on the State Water Board because California is located within the Ninth Circuit.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-8
achieve these minimum federal standards. In addition, the General Permit requires a SWPPP to be developed following specified standards and measures in this General Permit for implementation. This General Permit ensures that the dischargers do not “write their own permits” through discharger-requirements to implement specific BMPs, numeric action levels, and numeric effluent limitations, and SWPPP performance standards and information. As a result, this General Permit does not require each discharger’s SWPPP to be reviewed and approved by the Regional Water Boards.

I.B.3. U.S. EPA Construction and Development Effluent Limitations Guidelines and New Source Performance Standards2
The U.S. EPA promulgated Effluent Limitation Guidelines and New Source Performance Standards on December 1, 2009, to control the discharge of pollutants from construction sites (See 74 Fed. Reg. 62996, and 40 Code of Federal Regulations § 450.21.). These requirements, known as the “Construction and Development Rule” became effective on February 1, 2010. Following the promulgation of the Construction and Development Rule in 2009, several parties filed petitions for review of the final rule, identifying potential deficiencies with the dataset that the U.S. EPA used to support its decision to adopt a numeric turbidity limitation as well as other issues. The U.S. EPA finalized amendments to the Construction and Development Rule on March 6, 2014, resulting in the removal of the numeric turbidity limitation and monitoring requirements and clarifying changes in the U.S. EPA’s 2017 and 2022 NPDES General Permit for Discharges from Construction Activity (Construction General Permit) (See 79 Fed. Reg. 12661 and 80 Fed. Reg. 25235) pursuant to a settlement agreement to resolve the litigation.

The U.S. EPA 2022 Construction General Permit was adopted and went into effect on February 17, 2022.
a. Summary of Construction and Development Rule Requirements The Construction and Development Rule requirements include effluent limitations that apply to all permitted discharges from construction sites (40 Code of Federal Regulations § 450.21) for six general categories: i.) Erosion and Sediment Controls, ii.) Soil Stabilization Requirements, iii.) Dewatering, iv.) Pollution Prevention Measures, v.) Prohibited Discharges, and vi.) Surface Outlets. The effluent limitations are structured to require construction operators to first, prevent the discharge of sediment and other pollutants using effective planning and erosion control measures; and second, control discharges that do occur using effective sediment control measures. Dischargers are required to implement a range of pollution control and prevention measures to limit or 2 U.S. EPA, Protection of Downstream Waters in Water Quality Standards: Frequently Asked Questions (June 2014), <https://www.epa.gov/sites/production/files/2018- 10/documents/protection-downstream-wqs-faqs.pdf> [as of May 20, 2021] ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-9
prevent discharges of pollutants, including those from stormwater and non- stormwater discharges. The narrative effluent limitations are designed to prevent or minimize exposure and mobilization of pollutants in stormwater discharge from: (1) sediment and sediment-bound pollutants such as metals and nutrients, (2) construction materials, debris, and other sources of pollutants on construction sites, dissolved construction pollutants, such as nutrients, organics, pesticides, herbicides, and metals, (4) natural pollutants present in construction site soil, such as arsenic or selenium, and (5) previous activities on the site such as agriculture or industrial activity. Source control through minimization of soil erosion is the most effective way of controlling the discharge of these pollutants because, once mobilized by rainfall and stormwater, pollutants can detach from the soil particles and become dissolved pollutants which are not removed by down-slope sediment controls. b. Incorporation of Construction and Development Rule into this General Permit This General Permit incorporates the necessary requirements to implement the 2014 Construction and Development Rule amendments. Information on how this General Permit incorporates the Construction and Development Rule is included below.
i. Erosion and Sediment Controls
This General Permit requires dischargers to design, install, and maintain effective erosion controls and sediment controls to minimize the discharge of pollutants through the development and implementation of a site-specific SWPPP and BMPs. The discharger’s SWPPP is required to include the site- specific measures implemented to control all construction activity-related pollutants through temporary and permanent erosion and sediment control BMPs (Order, Section IV.O and Attachments D and E). Dischargers are required to implement channel protection and post construction controls to match the pre-construction hydrograph to ensure the minimization of project impacts to downstream channels and streambanks due to erosion and scour, temperature, and loss of ecological services (Attachments D and E).

Dischargers are required to set back their construction activities from streams and wetlands unless infeasible to reduce the risk of impacting water quality (e.g., natural stream stability and habitat function). Although this General Permit does not mandate specific setbacks, these distances may be required as part of California Environmental Quality Act (CEQA) or the National Environmental Policy Act (NEPA), the Regional Water Board, municipal requirements, and/or other agencies such as the Department of Fish and Wildlife. The risk calculation and runoff reduction mechanisms in this General Permit are expected to facilitate compliance with any Regional Water Board, local resource agency, and/or California Environmental Quality Act (CEQA) or the National Environmental Policy Act (NEPA). The ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-10
U.S. EPA has provided requirements for determining buffer size.3 These requirements may provide helpful guidance for sizing construction sites buffers to limit the disturbance of creeks and natural drainage features.

Attachments D and E require the discharger to minimize soil compaction when feasible in site areas where final vegetation will occur, or infiltration features will be installed. Dischargers are required to preserve native topsoil on-site when feasible, unless the intended function of a specific area of the site dictates that the topsoil be disturbed or removed. This General Permit encourages dischargers to keep the clearing and grading of native vegetation at the site at a minimum where areas are needed to build the project and to allow fire protection access. An example of an alternative practice to grading is mowing vegetation and leaving the subgrade root structure and soil intact. A guidance document4 was developed in 2016 providing techniques to address the challenges with site stabilization and climate change. Dischargers are encouraged to:
1) Plan upfront for site stabilization to occur in months with more moisture to lower the need of imported water to stabilize vegetation; 2) Minimize the disturbance of soil to decrease the length of time and cost of final site stabilization;
3) Maintain the soil health to control stormwater pollution and erosion through open pore soil structures which support long-term sustainable vegetative cover;5 and
4) Apply proper stockpiling practices to preserve soil biota and the native seed bank which reduces the need for fertilizer, seed, and water.6 3 U.S. EPA, 2022. Construction General Permit, Appendix F – Buffer Requirements (2022). https://www.epa.gov/system/files/documents/2022-01/2022-cgp-final- appendix-f-buffer-reqs.pdf [as of July 19, 2022]
4 Construction General Permit (CGP) Training Team, CGP Review Issue #3 for QSD and QSP Registration and Renewal, Insights for Better Stabilization (2016), <https://www.waterboards.ca.gov/water_issues/programs/stormwater/docs/training/cg p_review_issue3.pdf> [as of May 20, 2021]
5 Caltrans, Erosion Control Toolbox <https://dot.ca.gov/programs/design/lap-erosion- control-design/tool-1-lap-erosion-control-toolbox> [as of May 20, 2021] 6 The American Association of State Highway Officials, Construction Practices for Environmental Stewardship Website, 2019. The American Association of State Highways Officials (AASHTO) includes best practices on stockpiling, including Section

4.11.1 on specific guidelines for preserving stockpiles in its online Environmental Stewardship Practices in Construction and Maintenance Compendium. AASHTO ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-11
ii. Soil Stabilization Requirements
This General Permit requires dischargers to implement soil stabilization BMPs whenever disturbance activities occur (e.g., clearing, grading, excavating, or other earth disturbing activities). Alternative stabilization measures must be employed as specified by Section III.H of this Order and Attachments D and E of this General Permit in arid, semiarid, and drought- stricken areas where initiating immediate vegetative stabilization measures is infeasible. Stabilization must be completed within a time period determined by the Regional Water Boards. Stabilization may not be required if the intended function of a specific area of the site necessitates that it remains disturbed in limited circumstances.
iii. Dewatering
This General Permit requires dischargers to implement BMPs to control the volume and velocity of dewatering discharges in Section IV.M of the Order.

Dischargers are required to minimize the discharge of pollutants from dewatering trenches and excavations through the implementation of BMPs.

Dischargers with dewatering activities subject to a separate NPDES, de minimis, or low threat discharger permit for dewatering activities are to obtain coverage through those permits issued by the State or Regional Water Board.
iv. Pollution Prevention Measures
Section IV.O of this Order requires that dischargers design, install, implement, and maintain effective pollution prevention measures to minimize the discharge of pollutants. The SWPPP requirements include the minimization of exposure of pollutants and discharge of pollutants from certain activities included in the Effluent Limitation Guidelines. This General Permit also incorporates specific TMDL requirements for construction stormwater sources to limit loading to impaired waterbodies. v. Prohibited Discharges
This General Permit authorizes only stormwater and authorized non- stormwater discharges associated with construction activity when in compliance with all General Permit requirements, provisions, limitations, and prohibitions. Section IV.B of this Order prohibits discharges from the following categories:
recommends stockpiling for up to 6 months, but no longer than a year, and a maximum stockpile height of 4 feet.
<https://environment.transportation.org/wp-content/uploads/2021/04/25-254_FR.pdf> [as of April 28, 2022]
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-12
1) Dischargers out of compliance with any applicable discharge prohibitions contained in applicable Basin Plans or statewide water quality control plans;
2) Discharges to Areas of Special Biological Significance (ASBS), unless granted an exception issued by the State Water Board; 3) All discharges to waters of the United States except for the stormwater and non-stormwater discharges specifically
authorized by this General Permit or in a separate NPDES permit; 4) Debris and trash resulting from construction activities; 5) Wastewater from washout or clean out of areas, structures or equipment with concrete, grout, stucco, paint or other construction materials;
6) Form-release oils and curing compounds;
7) Fuels, oils, fluids, or other materials used in vehicle and equipment operation and maintenance;
8) Soaps, solvents, or detergents used in vehicle and equipment washing or external building wash-down; and
9) Toxic or hazardous substances from a spill or other release (e.g., asbestos, lead, mercury, or polychlorinated biphenyls (PCBs). vi. Surface Outlets
Attachment J of the General Permit authorizes specific construction dewatering discharges and requires the dewatering activity to utilize outlet structures that withdraw water from the surface of the sediment basin or similar impoundment, unless infeasible.

I.C. Healthy Soils and Recycled Water
I.C.1. Healthy Soils Initiative
The State of California launched the Healthy Soils Initiative in 2015, which is a collaboration of state agencies and departments to promote the stewardship of healthy soils. The California Environmental Protection Agency is a Healthy Soils Initiative partner. The initiative recognizes that healthy soils can increase water retention and infiltration, improve plant health, prevent erosion, reduce sediment and dust, sequester carbon to reduce greenhouse gas emissions, improve water quality, and improve biological diversity and wildlife habitat.7 7 California Department of Food and Agriculture, California’s Healthy Soils Initiative, <https://www.cdfa.ca.gov/healthysoils/> [as of May 20, 2021] ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-13
This General Permit encourages healthy soils practices through requirements in Attachments D and E of this General Permit, which require dischargers to preserve native topsoil and reduce compaction of soils. Using healthy soils practices will encourage vegetative growth, increase soil stabilization, and conserve water on construction sites.

I.C.2. Recycled Water Use
The State Water Board adopted the Water Quality Control Policy for Recycled Water (Recycled Water Policy) and the Staff Report with Substitute Environmental Documentation on December 11, 2018 and became effective on April 8, 2019. The Recycled Water Policy states, “When used in compliance with this Policy, California Code of Regulations, title 22 and all applicable state and federal water quality laws, the State Water Board finds that recycled water is safe for approved uses, and strongly supports recycled water as a safe alternative to fresh water or potable water for such approved uses.”8
This General Permit encourages the use of recycled water for appropriate application on construction sites, including irrigation of vegetation and dust control when used in compliance with the Recycled Water Policy, California Code of Regulations, title 22 and all applicable state and federal water quality laws.

I.D. Blue Ribbon Panel of Experts (Panel)
I.D.1. Introduction
The State Water Board convened an expert panel (panel) in 2005 and 2006 to address the feasibility of numeric effluent limitations in California’s stormwater permits. Specifically, the panel was asked to address the following:

Is it technically feasible to establish numeric effluent limitations, or some other quantifiable limit, for inclusion in stormwater permits? How would such limitations or criteria be established, and what information and data would be required?9 8 State Water Resources Control Board, Water Quality Control Policy for Recycled Water (December 11, 2018),
<https://www.waterboards.ca.gov/board_decisions/adopted_orders/resolutions/2018/1 21118_7_final_amendment_oal.pdf> [as of April 28, 2022] 9 Storm Water Panel, The Feasibility of Numeric Effluent Limits to Discharges of Storm Water Associated with Municipal, Industrial, and Construction Activities (June 19, 2006),
<https://www.waterboards.ca.gov/water_issues/programs/stormwater/docs/numeric/s wpanel_final_report.pdf> [as of May 20, 2021]
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-14
I.D.2. The Panel observations:
· “Limited field studies indicate that traditional erosion and sediment controls are highly variable in performance, resulting in highly variable turbidity levels in the site discharge.”
· “Site-to-site variability in runoff turbidity from undeveloped sites can also be quite large in many areas of California, particularly in more arid regions with less natural vegetative cover and steep slopes.”
· “Active treatment technologies involving the use of polymers with relatively large storage systems now exist that can provide much more consistent and very low discharge turbidity. However, these technologies have to date only been applied to larger construction sites, generally five acres or greater.

Furthermore, toxicity has been observed at some locations, although at the vast majority of sites, toxicity has not occurred. There is also the potential for an accidental large release of such chemicals with their use.” · “To date most of the construction permits have focused on TSS and turbidity, but have not addressed other, potentially significant pollutants such as phosphorus and an assortment of chemicals used at construction sites.” · “Currently, there is no required training or certification program for contractors, preparers of soil erosion and sediment control Stormwater Pollution Prevention Plans, or field inspectors.”
· “The quality of stormwater discharges from construction sites that effectively employ BMPs likely varies due to site conditions such as climate, soil, and topography.”
· “The States of Oregon and Washington have recently adopted similar concepts to the Action Levels described earlier.”
I.D.3. Panel Conclusions:
· “It is the consensus of the panel that active treatment technologies make Numeric Limits technically feasible for pollutants commonly associated with stormwater discharges from construction sites (e.g., TSS and turbidity) for larger construction sites. Technical practicalities and cost-effectiveness may make these technologies less feasible for smaller sites, including small drainages within a larger site, as these technologies have seen limited use at small construction sites. If chemical addition is not permitted, then Numeric Limits are not likely feasible.”
· “The Board should consider Numeric Limits or Action Levels for other pollutants of relevance to construction sites, but in particular pH. It is of particular concern where fresh concrete or wash water from cement mixers/equipment is exposed to stormwater.”
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-15
· “The Board should consider the phased implementation of Numeric Limits and Action Levels, commensurate with the capacity of the dischargers and support industry to respond.”
I.D.4. The State Water Board Considerations:

The State Water Board carefully considered the findings of the Panel and related public comments in the development and adoption of the previous permit. The State Water Board also reviewed and considered the comments regarding statewide stormwater policy during the adoption of the Industrial General Permit.

From the input received, the State Water Board identified some General Permit and program performance gaps that were addressed in the previous permit and were also adopted in this General Permit. The Summary of Significant Changes (below) in this General Permit align with the Panel’s process and findings, and build onto the previous permit.

I.E. Summary of Significant Changes in This General Permit I.E.1. Significant Changes:
a. Implementation of Total Maximum Daily Loads (TMDL)
TMDLs are regulatory tools providing the maximum amount of a pollutant from potential sources in the watershed that a water body can receive while attaining water quality standards. A TMDL is defined as the sum of the allowable loads of a single pollutant from all contributing point sources (waste load allocations) and non-point sources (load allocations), plus the contribution from background sources. (40 Code of Federal Regulations § 130.2, subd. (i).) Discharges covered by this General Permit are considered to be point source discharges, and therefore must comply with effluent limitations that are “consistent with the assumptions and requirements of any available waste load allocation for the discharge prepared by the State and approved by U.S. EPA pursuant to 40 Code of Federal Regulations section 130.7.” (40 Code of Federal Regulations § 122.44, subd. (d)(1)(vii).) In addition, Water Code § 13263, subdivision (a), requires that waste discharge requirements implement relevant water quality control plans. Many TMDLs in existing water quality control plans include both waste load allocation and implementation requirements.

Attachment H of this General Permit lists the watersheds with U.S. EPA- approved and U.S. EPA-established TMDLs that include TMDL requirements for discharges covered by this General Permit.
i. Where waste load allocations are expressed at a value that is too low for laboratory methods listed in 40 Code of Federal Regulations Part 136 to detect and for pollutants that are sediment-bound, the Water Board has developed a soil screening investigation and total suspended solids numeric ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-16
effluent limitation for sediment-bound pollutants, presented in Attachment H Section I.G.5, to determine compliance.
b. Implementation of Statewide Trash Policy Requirements The State Water Board adopted an amendment to the Water Quality Control Plan for Ocean Waters of California to Control Trash and Part 1 Trash Provisions of the Water Quality Control Plan for Inland Surface Waters, Enclosed Bays, and Estuaries of California (Resolution 2015-0019) in 2015.

This Resolution establishes the statewide water quality objective and implementation plan to control trash.

This General Permit implements this Resolution by prohibiting the discharge of any debris and/or trash from construction sites.
c. Removal of Bioassessment Monitoring
The Bioassessment requirements in the previous permit were initially developed to align with a proposed State Water Board biological integrity policy, which is still under development.

The Bioassessment requirements in the previous permit were reviewed by State Water Board staff and it was determined the requirements were not consistently implemented and data was not generated. These requirements did not generate sufficient data regarding corresponding improvements to water quality or watershed heath that would justify the cost of compliance.

The Bioassessment requirements were removed from this General Permit and replaced with acknowledgement to use the Risk Level 3 and linear underground and overhead project Type 3 sites annual fee surcharge to perform monitoring, sampling, and/or bioassessment monitoring through the Surface Water Ambient Monitoring Program (SWAMP) to determine the impacts of large, high-risk construction projects on water quality and watershed health. Future reissuances of this General Permit may include bioassessment or biological integrity requirements to implement specific water quality control plans or state policy for water quality control.
d. Passive Treatment Technologies
State Water Board staff collaborated with stakeholders and other Water Board staff to discuss the use of passive treatment chemicals and technologies throughout the life of the previous permit, and it was determined that many passive treatment chemical types are potentially toxic to fish and other aquatic organisms. Staff also considered and reviewed regulations regarding these ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-17
technologies from U.S. EPA and several other jurisdictions.10,11,12 Cationic polyacrylamide-based flocculant products are acutely toxic to aquatic species in small quantities and are neurotoxins. Other flocculant products such as anionic polyacrylamide-based flocculants are chronically toxic to aquatic species in large quantities.

Staff additionally identified low-turbidity discharges from passive treatment chemical application sites do not always correspond to low levels of solids in the discharge and/or an improvement in water quality downstream because:
i. Turbidity monitoring solely measures small size solids suspended in the water; turbidity monitoring does not measure particle size, weight, or bed load of sediment from flocculated solids leaving a site; and ii. Passive treatment chemicals discharged either by aerial deposition or via stormwater runoff contributes similar level of threat to aquatic life from toxicity.

This General Permit contains passive treatment provisions in Attachment G designed to provide the first set of regulations for construction activities use of passive treatment technologies and to align with the U.S. EPA’s Construction General Permit requirements for treatment chemicals.
e. Water Quality Control Plan for Ocean Waters of California (California Ocean Plan)
On March 20, 2012, the State Water Board adopted Resolution 2012-0012 (amended by Resolution 2012-0031) which contained a general exception to the California Ocean Plan for discharges of stormwater and non-point sources.

This General Permit requires dischargers who discharge to Areas of Special Biological Significance (ASBS) who have been granted an exception to the California Ocean Plan to comply with requirements in Attachment I. 10 Toronto and Region Conservation, Anionic Polyacrylamide Application Guide for Urban Construction in Ontario (June 2013),
<https://sustainabletechnologies.ca/app/uploads/2013/02/Polymer-Guide- Final_NewFormat.pdf> [as of May 20, 2021]
11 State of Washington Department of Ecology, Emerging Stormwater Treatment Technologies (TAPE) (2018), <https://ecology.wa.gov/Regulations-Permits/Guidance- technical-assistance/Stormwater-permittee-guidance-resources/Emerging-stormwater- treatment-technologies> [as of May 20, 2021]
12 U.S. EPA, Support Document for the Third Six-Year Review of Drinking Water Regulations for Acrylamide and Epichlorohydrin (December 2016), <https://www.epa.gov/sites/production/files/2016-12/documents/810r16019.pdf> [as of May 20, 2021]
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-18
f. Sufficiently Sensitive Test Methods
U.S. EPA has finalized minor amendments to its Clean Water Act regulations to codify that under the NPDES program, where U.S. EPA has promulgated or otherwise approved analytical methods under 40 Code of Federal Regulations Part 136, or 40 Code of Federal Regulations Chapter I, subchapters N and O, dischargers must use “sufficiently sensitive” analytical test methods. The purpose of the rulemaking was to clarify that NPDES permittees must use U.S.

EPA approved analytical methods that are capable of detecting and measuring the pollutants at, or below, the applicable water quality criteria or permit limits.

This General Permit requires the use of sufficiently sensitive methods to meet the requirements of the amended Clean Water Act regulations described above and requires the discharger to ensure all laboratory analyses are sufficiently sensitive and conducted according to test procedures under 40 Code of Federal Regulations Part 136, including the observation of holding times, detection limits, and other measures designed to ensure quality assurance and quality control.

For any calculations required by this General Permit, a value of zero (0) will be assigned for all analytical results less than the minimum level as reported by the laboratory, so long as a sufficiently sensitive method was used (as evidenced by the reported method detection limit and minimum level which is also referred to as the reporting limit).
g. Notice of Non-Applicability
California Water Code § 13399.30 sets forth the authority for the Water Board to provide entities (referring to the person) a process for determining this General Permit does not apply to the entity’s activities through a Notice of Non- Applicability. The addition of the Notice of Non-Applicability provisions in this General Permit addresses the determination process and required information for construction sites situated in areas where stormwater discharges to waters that are not hydrologically connected to waters of the United States. h. Sampling and Monitoring Requirements
Sampling and Monitoring requirements have changed in this General Permit as follows:
i. The Qualified SWPPP Developer (QSD) and Qualified SWPPP Practitioner (QSP) have additional requirements to visit the site, conduct visual inspections, and assess site conditions;
ii. The QSDs and QSPs are required to do on-site visual inspections at intervals that reflect potential changes to the construction site (e.g., start of construction, replacement of a QSD, twice yearly); and
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-19
iii. Samples must be collected during precipitation events with 0.5”13 or more predicted within a 24-hour period. This is defined as a Qualifying Precipitation Event for sampling and inspection requirements. The stormwater can be water from rain, snow, or any other precipitation.

Qualifying Precipitation Events continue on subsequent 24-hour periods that have precipitation of 0.25” or more forecast, and end with two consecutive 24-hour periods with less than 0.25” forecast.
i. Removal of Rain Event Action Plan
The previous permit designed the Rain Event Action Plan (REAP) to provide an on-site inspection checklist for dischargers to implement requirements prior to a precipitation event. This tool has been discussed over the last ten years internally and externally with stakeholders. This General Permit implements more action-based requirements in lieu of the reporting-based strategy embodied by the REAP. This General Permit replaces REAPS with 1) QSD involvement over the life of the project, 2) additional inspections and visual observations, and 3) an increased requirement to document and implement these site corrective actions.
j. Notice of Termination Process
The Notice of Termination requirements have been updated to include additional project-specific termination information to streamline the Regional Water Board review process. Given that the Notice of Terminations should now be submitted with the complete details to determine approval, this General Permit includes an automatic approval provision after 30 days if not otherwise under review or addressed by the Regional Water Board. This change is to expedite Notice of Termination approval and to reduce the risk of prolonged financial burdens on dischargers for continued on-site monitoring and annual fee payments.
k. Appendices 2 and 2.1 Post Construction Water Balance Calculator The previous permit included post-construction performance standards requirements and information in Appendices 2 and 2.1. These specific appendices have been removed from this General Permit because these requirements and information are now in Stormwater Applications and Reports Tracking System (SMARTS) and are available for review through the public SMARTS portal. Additionally, Appendix 2 had requirements for post- construction maps contours. This requirement has been removed in this General Permit because this General Permit includes additional SWPPP map requirements and Notice of Termination map requirements. After adoption of 13 Xie, W., et. al. (2016). Models for Estimating Daily Rainfall Erosivity in China. Journal of Hydrology v. 535, p. 527-558.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-20
this General Permit, the State Water Board may hold public or focused stakeholder meetings to discuss any necessary updates or changes to the post-construction water balance calculator in SMARTS. Some of this information will also be incorporated into online web-based maps, calculators, and/or visualizations as implementation guidance to the regulated community.

I.F. Cost Considerations
I.F.1. Passive Treatment Technology Provisions
The passive treatment technologies (passive treatment) requirements in this General Permit provide a regulatory pathway for dischargers to treat runoff for excess sediment without the use of an active treatment system while protecting water quality. The new passive treatment provisions were added due to requests from the regulated community, regulatory staff, and other stakeholders. The major components of the new Passive Treatment provisions that have expected cost components are: 1) consultant or discharger hours to develop and implement the Passive Treatment Plan, and 2) hours for Qualified SWPPP Developer (QSD) to implement the Passive Treatment Plan and monitor passive treatment application and use.
a. Hours for consultants and/or dischargers to develop and implement the Passive Treatment Plan.

The passive treatment technologies in Attachment G requires the development of the Passive Treatment Plan. The costs associated with development and execution of the Passive Treatment Plan are in labor hours, training, collection of manufacturer information and potential hazards to the environment, and research on site-specific implementation of the Attachment G requirements.

These costs, based on an hourly QSD billing rate of $80 to $120, are estimated at $3,000 to $5,000.
b. QSD hours to implement Passive Treatment Plan and monitor site-specific passive treatment application and use, including post-event sampling.

A QSD is needed to develop and implement the Passive Treatment Plan and will require office and field hours for that individual. This is often a contracting cost to a consultant from the discharger or payment of QSD-staff hours for the discharger’s organization. This cost will be highly variable, depending on the amount and duration of exposed soil conditions and the number of precipitation events that produce discharge from a site. The range is therefore estimated at $2,500 to $6,500 per year for the QSD and $500 to $1,250 in laboratory analysis costs.

I.F.2. Training
The reissuance of this General Permit requires updates to the QSD and QSP training program first introduced in the previous permit. Additional and revised ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-21
training for all parties implementing this General Permit have been identified since 2009 and incorporated into this reissuance. Specific training needs to include: 1) Qualified SWPPP Developers (QSDs) and Qualified SWPPP Practitioners (QSPs) revised roles on the site, 2) training for passive treatment and TMDL implementation, and 3) statewide re-test and/or re-certification of Qualified SWPPP Developers, Qualified SWPPP Practitioners, and Trainers of Record. a. QSD and QSP revised site roles
The Order and Attachments D and E require more involvement by the QSD and QSP, which is a potential increase in cost to the discharger as these are often contracted positions. Additional duties for the QSD under this permit include required field inspections and post-storm monitoring of passive treatment systems. On average, these duties should require 5 to 7 additional field days per year, at an estimated cost of $4,000 to $6,000, and up to two additional office days per year, at an estimated cost of $1,600. The revised roles for the QSP are expected to result in discharger savings, particularly since the increased QSD inspections may reduce QSP field time.
b. Additional training needed for passive treatment and TMDL implementation.

QSD and QSP personnel will need additional training to come up to speed on the new provisions of this General Permit. New requirements such as passive treatment and TMDL implementation will extend training content and create a learning curve for QSDs and QSPs trained under the previous permit. A four- hour refresher-level course would provide adequate additional training on these subjects, at an estimated cost of $200 to $250 for the training and $150 to $225 for the employee’s time.
c. Potential statewide re-test and re-certification
If the Construction General Permit Training Team determines that all QSD/QSPs need to be re-tested or somehow re-certify their knowledge, this could incur costs to the state as well as to the dischargers for time spent.

Assuming that any such re-testing and re-certification would be an online process, the additional cost would amount to two or three hours of employee time, or up to $125.

I.F.3. Cost Variability
The State Water Board recognizes that there is high variability in cost across all construction projects. Cost variability relates to many factors including: 1) short term vs. long term projects, 2) risk level of the project, and 3) construction season/schedule. Below is a discussion of these variables and their impact on overall cost for implementation of the General Permit.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-22
a. Short-term vs. long-term projects
Costs associated with the Construction General Permit are already variable due to the ephemeral nature of construction projects and the variation in size and site conditions. Short-term projects that can be completed during dry periods will incur minimal or no additional costs between permits, with expenditures still proportional to size. Projects that span one or more wet periods with more difficult erosion and sediment control issues, or sites that are in a TMDL watershed, will likely have more costs. This can be mostly attributed to increased QSD oversight and additional sampling and analysis requirements. b. Risk dependent
The project risk calculation creates great variability in BMP cost, ranging from as little as 0.5 percent of the project total for Risk Level 1 site to four percent of the project total for Risk Level 3 sites. Higher risk sites will have more costs associated with BMPs, potential use of passive treatment, active treatment, increased monitoring requirements, and costs associated with discharging to high-risk receiving waters.
c. Construction activity season and schedule
The General Permit implementation costs are minimized for construction projects that use scheduling as a primary BMP and that schedule construction outside of time periods with likely precipitation events. The requirement for advanced BMPs is reduced, including cost associated with treatment (passive or active) if there is no water on-site. Sampling and analysis costs will be non- existent if no discharge occurs.

I.F.4. Savings
This General Permit includes several cost saving areas. After the previous permit, the State Water Board analyzed the provisions that were clear and enforceable, resulted in valuable data collection, and improved water quality. Changes were made to the previous permit to address areas that were not providing valuable data or improving water quality, including: 1) removal of the Rain Event Action Plan (REAP), 2) revised monitoring and sampling frequency, 3) clarifying the allowance of an inactive project status, 4) improved efficiency for reporting and data collection in SMARTS, 5) programmatic permitting for linear underground and overhead projects, and 6) including a 30-day automatic Notice of Termination approval unless notified by the Regional Water Board that the Notice of Termination is denied, returned, or accepted for review.
a. Rain Event Action Plan removal
The development and implementation of the Rain Event Action Plan in the previous permit resulted in minimal data and un-documented improvements in water quality. The removal of this requirement will save the discharger time and ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-23
money, estimated at $2,500 to $3,500 per year in report preparation and $350 to $500 for labor.
b. Revised monitoring frequency
This General Permit includes a revised monitoring frequency that aligns with real-time site conditions and focuses on the implementation of BMPs and inspections. These requirements still ensure representative sampling and monitoring are conducted and includes BMP evaluations after numeric action level exceedances. For a one-year project duration, the savings are estimated at $1,750 to $2,000.
c. Inactive project status
Cost savings for sites to reduce monitoring and inspections during periods of inactivity. The savings come from fewer SWPPP implementation and monitoring hours for consultants and site personnel.
d. Annual Report, SMARTS, and implementation tools
The Annual Report is being redesigned to reduce the number of additional uploads and completion time for the discharger. When feasible, screens will be enhanced to streamline system use and staff is working on implementation tools outside of SMARTS (e.g., web-based maps).
e. Programmatic permitting for linear underground and overhead projects Allowing linear underground and overhead projects to certify and submit one Notice of Intent for projects that have similar construction activity scopes and are located within one Regional Water Board office boundary will save time and money in application processes, changes of information, and initial inspections.

I.G. Incorporation of Total Maximum Daily Load (TMDL) Requirements and Cost I.G.1. Introduction
This General Permit’s TMDL requirements provide a consistent implementation approach for TMDLs with similar pollutants and waste load allocations, streamlining the process for construction projects to achieve compliance.

Responsible Dischargers are required to implement applicable TMDL waste load allocations through the following TMDL-specific requirements developed for this General Permit: compliance with this General Permit, Revised Universal Soil Loss Equation, Version 2, (RUSLE2) modeling, numeric action levels, and/or numeric effluent limitations. This consistency between TMDLs provides cost-efficient implementation for Responsible Dischargers in achieving compliance with applicable TMDL requirements. The discussion below is to provide:
a. An overview of TMDL implementation where the State Water Board has provided cost-efficiencies;
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-24
b. General information on TMDL pollutant categories and estimated compliance costs associated with TMDL requirements for Responsible Dischargers; c. Examples of appropriate existing BMPs; and
d. General costs (high, medium, low) for potential TMDL-pollutant BMP categories.

I.G.2. Using this General Permit’s Implementation Framework Costs are site-specific and vary depending on multiple factors described categorically in Section I.F.3 above. This general information is provided to frame the cost considerations for Responsible Dischargers implementing applicable TMDL waste load allocation requirements. The incorporation of TMDL requirements into this General Permit allows for the use of its monitoring and reporting framework to avoid, where possible to meet the TMDL requirements, incurring additional costs associated with TMDL implementation (e.g., additional and separate reports for numeric action level and numeric effluent limitation exceedances, unique monitoring and sampling requirements specific to TMDLs). a. The TMDL implementation requirements in this General Permit rely on Responsible Dischargers to complete a thorough pollutant source assessment for the entire duration of their construction project, which shall be included within their SWPPP. Only Responsible Dischargers that identify on-site sources of pollutants associated with an applicable TMDL, as listed in Attachment H, are required to comply with additional TMDL requirements. This provision takes into consideration construction site pollutant source variability and reduces the implementation burden to implement TMDL requirements for pollutants that are not present on their site from construction activities. The additional cost for a TMDL-level pollutant source assessment is estimated at $1,000 to $1,250, including additional field time and SWPPP preparation. Dischargers complying with the alternative approach described in Section I.W.6.g.vi of this Fact Sheet may incur additional costs related to the soil screening required as part of the pollutant source assessment. The soil screening cost is estimated at $200 per sample.
b. Twenty-nine (29) of the TMDL waste load allocations have been translated to require compliance with this General Permit, without imposing additional RUSLE2 modeling, numeric action levels, or numeric effluent limitations. c. Ninety-three (93) TMDL waste load allocations were translated to require using RUSLE2 modeling to demonstrate a construction site’s annual soil loss will not deliver more sediment to a water body than pre-construction conditions. This translation was derived in consideration of costs for TMDLs with mass-based waste load allocations, rather than imposing TMDL-specific monitoring requirements for pollutants that are associated with sediment discharges.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-25
d. Sixty-two (62) of the TMDL waste load allocations have been translated to require numeric action levels, to consistently implement the General Permit’s framework using numeric action levels compliance and reporting. Responsible Dischargers are required to follow the same stormwater management requirements for both TMDL-related and non-TMDL-related numeric action level exceedances in this General Permit. TMDLs with concentration-based waste load allocations to be met in receiving waters, are translated into numeric action levels to be met at the construction site discharge location(s), to avoid costly and often infeasible receiving water monitoring. e. Twenty-one (21) TMDL waste load allocations have been translated to impose numeric effluent limitations for pollutants, with required assessments and monitoring consistent with the regulatory framework of this General Permit.

However, Responsible Dischargers will follow the water quality based corrective action process in this General Permit and perform the required actions for TMDL-related numeric effluent limitation exceedances instead of a numeric effluent limitation violation report required for non-TMDL numeric effluent limitations. A Responsible Discharger that exceeds a TMDL-related numeric effluent limitation is in violation of this General Permit and may be subject to mandatory minimum penalties, whereas numeric action level exceedances are not violations of this General Permit. Only applicable TMDLs with concentration-based waste load allocations, to be met at the construction site discharge location(s), were translated into numeric effluent limitations.

I.G.3. TMDL-related Numeric Action Level and Numeric Effluent Limitation Exceedances The incorporation of TMDL implementation requirements may represent an increase in the cost of compliance for certain Responsible Dischargers. The following conditions must occur for a Responsible Discharger to exceed an applicable TMDL-related numeric action level or numeric effluent limitation:

Condition 1: The discharger discharges stormwater and authorized non- stormwater, either directly or through a municipal separate sewer system or other conveyance, to impaired water bodies or watersheds identified in a U.S. EPA- approved TMDL that assigns a concentration-based waste load allocation to construction stormwater discharges. Concentration-based waste load allocations are translated into numeric effluent limitations or numeric action levels and are listed in Attachment H, Table H-2.

Condition 2: The discharger identifies through the site-specific pollutant source assessment that one or more TMDL-specific pollutants are present at the site with the potential to enter discharge.

If the above conditions occur, the discharger is considered a Responsible Discharger for a TMDL, and subject to TMDL-related numeric action levels or numeric effluent limitations.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-26
Condition 3: The Responsible Discharger triggers the non-visible sampling requirements for the TMDL-specific pollutant when the pollutants may be discharged due to failure to implement BMPs, a container spill or leak, or a BMP breach, failure, or malfunction.

If the spill or leak, or BMP breach, failure or malfunction are immediately cleaned up and BMPs to control the pollutant were implemented, maintained, or replaced prior to the discharge, the Responsible Discharger is not required to sample its discharge.

Condition 4: The discharger conducts non-visible sampling in accordance with Attachment D, Section III.D.3, and Attachment E, Section III.D.3 and the analytical results report a concentration for the TMDL-specific pollutant above the applicable TMDL-related numeric action level or numeric effluent limitation listed in Attachment H, Table H-2.

Condition 5: Conditions 3 and 4 occur at least twice for any and all discharge locations within the same drainage area, during a given reporting year (July 1 through June 30). Each of the discharger’s subsequent analytical results reporting a concentration above the TMDL-related numeric action level or numeric effluent limitation, after the second occurrence, is considered a distinct exceedance.

A Responsible Discharger violates a TMDL-related numeric effluent limitation only after all the above conditions occur. Responsible Dischargers that exceeded a TMDL-related numeric effluent limitation or numeric action level will continue to implement iterative corrective actions and BMP implementation to prevent further exceedances. Dischargers that do not take corrective actions following an exceedance are in violation of this General Permit.

I.G.4. Availability of Implementation Tools
The State Water Board recognizes the need to provide Responsible Dischargers tools and information to navigate the applicability of TMDL requirements, determine the spatial location of the requirements, and provide support for compliance analyses. To reduce the Responsible Discharger’s cost of complying with the TMDL requirements, state-developed tools to assist in the implementation of and compliance with the TMDL requirements will be made free and publicly available. These include a TMDL applicability flowchart, a GIS-based TMDL applicability map, and additional implementation guidance and training for potential compliance methods.

I.G.5. TMDL Pollutant Categories
This General Permit implements a number of TMDLs separated into the following seven TMDL pollutant categories:
a. Bacteria
b. Chloride and salts
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-27
c. Diazinon
d. Nutrients
e. Sediment
f. Temperature
g. Metals and Toxics
Attachment H, Table H-2 of this General Permit lists all TMDLs applicable to Responsible Dischargers. For each TMDL, Table 2 cross-references one or more of the pollutant categories above.
a. Bacteria14,15
Sources of bacteria and other pathogens in watersheds include, but are not limited to, animal excrement (from stormwater infrastructure and animals) and sanitary sewer overflows of human excrement. Major contributors from construction sites may include wild or tamed animals on the premises, waste handling, portable toilets, and contaminants in erodible materials. This Fact Sheet contains supportive information referenced from the bacteria TMDLs that construction stormwater dischargers are not a significant source of bacteria and therefore would meet the waste load allocations.

The bacteria TMDLs in Attachment H require the implementation of existing minimum BMPs to control stormwater exposure to bacteria sources, thus compliance with these TMDLs is not expected to result in significant additional costs.
b. Chloride and Salts16
Salts such as boron, calcium chloride (CaCl), magnesium chloride (MgCl), sodium chloride (NaCl), and sulphate can accumulate in soils within the watershed. Three TMDLs in Attachment H identify construction stormwater 14 Los Angeles Regional Water Board, Ballona Creek, Estuary, and Tributary Bacteria TMDL (June 7, 2012),
<https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/docs/R12- 008_RB_BPA.pdf> [as of May 20, 2021]
15 CASQA, Construction BMP Handbook (January 2015),
<https://www.casqa.org/sites/default/files/casqa-handbook- construction/master_hanbook_file_2015_sec.pdf> [as of May 20, 2021] (CASQA Construction BMP Handbook)
16 Los Angeles Regional Water Board, Calleguas Creek Watershed Salts TMDL (October 4, 2007),
<https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/docs/2007- 016_RB_BPA.pdf> [as of May 20, 2021]
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-28
dischargers as potential sources of chloride and salts. For two of the three TMDLs, compliance with this General Permit was sufficient to meet the assigned waste load allocations, thus not imposing any TMDL-specific costs on the Responsible Dischargers. However, the Upper Santa Clara River TMDL for chloride assigned a concentration-based waste load allocation, which was translated into a numeric action level. As a result, Responsible Dischargers for the Upper Santa Clara River Chloride TMDL can expect a medium to low-cost impact.

Responsible Dischargers in the Upper Santa Clara River watershed (Region 4) may be required to conduct non-visible pollutant monitoring to analyze for boron, chloride, sulfate, and total dissolved solids as part of the TMDL implementation requirements. The estimated additional cost of the non-visible pollutant monitoring for the Upper Santa Clara River TMDL would be approximately $200-$400 for sampling and $150-$250 for analysis and SMARTS data entry, per sampled discharge location per event. c. Diazinon17
Diazinon is an organophosphate pesticide that does not sorb to sediment but is instead mobilized through soils by dissolving in water. Stormwater runoff can come into contact with areas where diazinon was applied and transport the pollutant into the watershed. Although diazinon was once used in both agricultural and urban settings, it has since been banned for non-agricultural uses by the California Department of Pesticide Regulations. Because this General Permit requires all dischargers to perform a pollutant source assessment, and diazinon is banned for non-agricultural uses, compliance with the diazinon TMDL requirements is not expected to incur additional costs. d. Nutrients18,19
Nutrients (e.g., ammonia, nitrogen compounds, and phosphorous) can be found in stormwater runoff from construction sites, industrial areas, and urban areas.

Sources of nutrients from construction sites may include background 17 San Diego Regional Water Quality Control Board, Chollas Creek Diazinon Total Maximum Daily Load (August 14, 2002)
<https://www.waterboards.ca.gov/sandiego/water_issues/programs/tmdls/chollascreek diazinon.html> [as of May 20, 2021]
18 United States EPA Region IX, Los Angeles Area Lakes Total Maximum Daily Loads for Nitrogen, Phosphorus, Mercury, Trash, Organochlorine Pesticides and PCBs (March 26, 2012),
<https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/Established /Lakes/LALakesTMDLsEntireDocument.pdf> [as of May 20, 2021] 19 CASQA Construction BMP Handbook, p. 1-7.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-29
concentrations, storage and application of fertilizers, and discharges of nutrient- rich sediments. Most of the nutrient TMDLs in Attachment H require that dischargers comply with waste load allocations by meeting the translated numeric action levels or numeric effluent limitations, while one TMDL relies on RUSLE2 modeling. The compliance cost impact for implementation of the nutrient TMDLs is expected to be medium to high since additional BMPs (filter media BMPs for phosphorus and advanced BMPs for nitrogen) and monitoring may be required for controlling the specific nutrient concentrations from construction sites.

The RUSLE2 modeling used to demonstrate compliance with the San Diego Creek and Newport Bay Nutrients TMDL in Region 8 is estimated to add $750 to $1,500 in costs, per project.

If non-visible pollutant monitoring is required, Responsible Dischargers in some watersheds located in Regions 3, 4 and 8 (Central Coast, Los Angeles Basin and Santa Ana), as specified in Attachment H, shall conduct analyses for the TMDL-specific pollutant(s) such as total nitrogen, ammonia, nitrates, nitrites, phosphorous, and orthophosphates. The estimated additional cost of the TMDL monitoring would be approximately $200-$400 for sampling and $200-$400 for analysis and SMARTS data entry, per sampled discharge location per event.

The May 2021 draft of the Construction Stormwater General Permit, issued for public comments, proposed translations of nitrogen-based nutrient waste load allocations into numeric effluent limitations. The translation of the nitrogen- based nutrient waste load allocations was revised to numeric action levels in this General Permit per the following explanation that numeric action levels are consistent with the assumptions and requirements of the waste load allocations.

All applicable TMDLs with nitrogen-based nutrient waste load allocations discuss low flow as the critical condition for the receiving water impairment.

Unlike general urban runoff that occurs year-round, construction stormwater discharges only occur as a result of precipitation events; discharges from construction sites do not typically occur during low flow receiving water conditions. A numeric action level is a more appropriate limitation to implement a TMDL primarily concerned with dry weather discharges. Further, each TMDL discusses municipal wastewater treatment plants as a principal source of nutrient loading. Although stormwater is identified as a potential source, the TMDL did not calculate a source-specific waste load allocation and instead used the water quality objective as the waste load allocation for nutrients.

Although the TMDLs sets the compliance location at the point of discharge, because of how the waste load allocation was calculated, the waste load allocations are similar to TMDLs where the compliance point is set at the receiving water. As set forth in Section I.D.3, this General Permit translated ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-30
concentration-based waste load allocations to be met in receiving waters into numeric action levels.

The State Water Board has very few nitrogen-based nutrient sampling results from construction stormwater because the previous permit did not require sampling for nutrients. However, nutrient data is available from required monitoring in the Industrial Stormwater General Permit. An analysis of all stormwater data from implementation of the Industrial Stormwater General Permit from 2015 – 2021 shows that of collected nutrients samples, approximately 95 percent of nitrate-plus-nitrite samples (as nitrogen), and 92 percent of ammonia samples had concentration results were lower than numeric action levels listed in this General Permit. The average sampling results, 0.68 mg/L for nitrate-plus-nitrite and 2.16 mg/L for ammonia, were below the numeric action levels in the Industrial Stormwater General Permit.

Both observed average sampling results are a fraction of the action levels in this General Permit. The sampling results available through the implementation of the statewide Industrial Stormwater General Permit include stormwater discharge data from industrial facilities, such as fertilizer manufacturers, with significant potential sources of nutrients. In contrast, sources of nutrients from construction sites are generally limited to existing legacy concentrations in the sediment from past land uses that involved application of fertilizers, pesticides, and herbicides, and storage facilities that store the chemicals. Accordingly, it is generally expected that construction stormwater discharges will not exceed the waste load allocations and numeric action levels are appropriate.

Numeric action levels are consistent with the TMDLs and protective of water quality. All dischargers are required to implement sediment control BMPs and eliminate or minimize site erosion. If the Discharger exceeds the numeric action level, as set forth in Attachment H, Section I.D.3.e, the discharger must report and respond to a numeric action level exceedances. As described in Attachment D and E, Section III.G, when there is an exceedance of a numeric action level, dischargers must determine the source of the pollutant, implement corrective actions to reduce or prevent further exceedances and implement iterative corrective actions until the discharge is in compliance with the action level. Within 14 calendar days of an exceedance, a QSD and QSP must perform on-site visual inspections and the QSP must document any areas of concern (Order, Section V.C.3 & V.D.4). For example, if the construction activities include the application or storage of fertilizers, pesticides, and herbicides, exposure of those products to stormwater must be prevented or minimized. Corrective actions may also include implementing BMPs that eliminate stormwater discharges, BMPs with filter media, or other sediment control BMPs. The Regional Water Boards may require additional monitoring, reporting, and BMP requirements upon obtaining site-specific information about an exceedance to a numeric action level (Attachment H, Section I.D.3.f). The ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-31
State Water Board expects that dischargers can feasibly comply with the nitrogen numeric action levels in this General Permit without the need to implement more advanced BMPs, which as discussed below are not typically possible to install at construction sites.

The most effective BMPs for removal of nitrogen-based nutrients through denitrification, biofiltration, or bioretention are advanced structural treatment BMPs that are used at permanent sites, not temporary construction sites.

Denitrification, the process by which nitrates are reduced to gaseous nitrogen by facultative microbes under anaerobic conditions, is often employed at wastewater treatment plants with numeric effluent limitations for ammonia and/or nitrates. Biofiltration BMPs capture and treat stormwater runoff using conditioned soil beds for planting vegetation and establishing microbial communities to filter out pollutants. Denitrifying treatment and bioretention BMPs requires the retention of all the construction site’s stormwater. Sites would need adequate space to accommodate the proper sizing and design of such treatment BMPs to effectively remove nutrients. Construction sites often have limited available area, and the larger the site, the more area is needed for treatment BMPs. Construction of permanent BMPs is not typically compatible with construction stormwater management, as site conditions are inherently transient during the term of the construction, and the nutrient removal BMPs would only be needed during land disturbance activities.

Biofiltration basins require established vegetation to efficiently remove nutrients. The vegetation in a biofiltration basin typically needs, at minimum, several growing seasons, (at minimum several months under ideal weather and soil conditions, up through several years under non-supportive growing conditions), for the vegetation to establish itself and provide effective treatment for nutrient removal. Most construction projects are active for a short duration with insufficient time to establish a vegetative biofiltration process that effectively removes nutrients. Although biofiltration is a commonly used post- construction BMP, its utility during construction is limited due to the inability to move biofiltration BMPs; additionally, biofiltration BMPs are designed specifically to treat a defined stormwater discharge quality under specific site conditions. Biofiltration BMPs are expensive, generally costing tens-of- thousands of dollars in addition to the cost of retention of the site’s stormwater.

Due to the time period needed to design and establish effective treatment, the long-term nature of treatment implementation, and the relative cost, biofiltration BMPs are not well-suited for construction sites that are temporary in nature.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-32
e. Sediment 20
Excess sediment delivery to stream channels can be a pollutant and is associated with several natural processes as well as anthropogenic sources.

Sediment can transport other pollutants that attach to it, including nutrients, trace metals, and organic compounds. Sediment is the primary component of turbidity, the most common sediment water quality analytical parameter used in this General Permit. Anthropogenic construction sources include, but are not limited to, track in and out from earth moving equipment, unpaved access road- related erosion (e.g., construction and maintenance of paved and unpaved roadways), dust, and soil/earth disturbing activities. All Responsible Dischargers are required to comply with the existing requirements of this General Permit, including the turbidity numeric action levels, associated exceedance actions, and the sediment TMDLs incorporated into this General Permit. However, many of the sediment TMDLs will also require additional RUSLE2 modeling to demonstrate compliance with the assigned waste load allocations. Responsible Dischargers for the Los Peñasquitos Lagoon Sediment TMDL are required to submit an estimate of the representative flow rate from their construction site for one precipitation event, each reporting period. Although imposing these additional requirements is expected to result in a low to medium cost impact for Dischargers, they were considered a more cost-effective approach than other means of complying with the TMDL such as TMDL-specific monitoring.

The cost of a runoff flow rate assessment varies by methodology and the method is often determined by the availability of input data. A relatively simple equation such as the Rational Method would require an hour or less for a QSD to calculate. The more complex and accurate National Resources Conservation Service method may require a site visit or extensive internet research and take two to six hours to complete. This translates to a cost range of $100 to $600, based on an average billable rate of $100 per hour for QSDs.

In addition to the regular numeric action level sediment monitoring required by the permit, Responsible Dischargers in some watersheds located in Region 1, as specified in Attachment H, shall conduct RUSLE2 to demonstrate compliance with the waste load allocations. The estimated additional cost of the RUSLE2 calculation requirement will add $750 to $1,500 to each project in these Regions.
20 California Stormwater Quality Association (CASQA) Construction BMP Handbook, p. 1-7.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-33
f. Temperature21
This General Permit includes seven temperature TMDLs, all of which are located in the North Coast Regional Water Quality Control Board’s jurisdiction.

The removal of riparian vegetation from road building and urbanization construction are amongst the sources observed to increase Northern California stream temperatures, which can negatively impact juvenile salmonids.

Excessive sediment input also raises stream temperature by widening stream channels, filling pools, and eliminating riparian vegetation during flood events.

Responsible Dischargers are required to comply with the requirements of this General Permit in order to achieve the applicable waste load allocations in the North Coast Temperature Implementation Policy. Compliance with these TMDLs is not expected to result in additional costs.
g. Metals and Toxics22
Metals (e.g., aluminum, cadmium, chromium, copper, lead, mercury, nickel, and zinc) and selenium can be found in construction stormwater discharges and are potentially toxic to aquatic life. Many of the equipment and materials used in the built environment (e.g., pipes, rebar, conductors, galvanized metal, paint, vehicles, preserved wood, tires, and vehicle brakes) contain metals, which enter stormwater as the surfaces corrode, decay, dissolve, flake, leach, or rust.

Toxic, synthetic organic compounds (e.g., adhesives, cleaners, herbicides, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), pesticides, sealants, solvents) may be found in low concentrations but can still be toxic to aquatic life. Sources of synthetic organic compounds at construction sites include, but are not limited to, exposure of the compounds to stormwater during use and/or storage, improper disposal, and accidental release into storm drains or off-site.

The primary transport mechanism for metals and toxics is the mobilization and discharge of fine sediment through stormwater. Metals and organic compounds have an affinity for other organic substances and will partition from water and sorb to sediment. For this reason, it was appropriate to translate mass-based waste load allocations into requiring additional RUSLE2 modeling to estimate sediment delivery from a construction site into a watershed. Using RUSLE2 to 21 United States Environmental Protection Agency Region IX, Final Upper Main Eel River and Tributaries (including Tomki Creek, Outlet Creek and Lake Pillsbury) Total Maximum Daily Loads for Temperature and Sediment (December 29, 2004) <https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/eel_river_u pper_main/pdf/uer-tmdl-final-12-28.pdf> [as of May 20, 2021] 22 CASQA Construction BMP Handbook, p. 1-7.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-34
demonstrate compliance with the waste load allocations avoids cost impacts associated with monitoring for toxic and metal pollutants.

However, a number of the metal and toxics TMDLs are assigned concentration- based waste load allocations, which were translated into numeric action levels or numeric effluent limitations. Many dischargers are not currently implementing BMPs designed to minimize concentrations for metals and toxics, but many Responsible Dischargers will need to implement BMPs designed to comply with the TMDL requirements. The compliance cost impact for the metal and toxics TMDL implementation is expected to be similar to that for normal sediment removal unless site-specific advanced BMPs and additional monitoring are required to comply with the requirements of these TMDLs. In the latter case, more advanced systems such as bioretention ponds, active treatment systems, or membrane filtration structures will likely have costs in the tens of thousands of dollars.

If non-visible pollutant monitoring is required, Responsible Dischargers in some watersheds located in Regions 4, 8 and 9 (Los Angeles Basin, Santa Ana, San Diego), as specified in Attachment H, would have to conduct TMDL analyses for metals and toxics listed for the individual watersheds. These pollutants may include copper, lead, zinc, mercury, nickel, cadmium, chromium and selenium, and toxics in the form of organochlorine pesticides, polychlorinated biphenyls (PCB), and polycyclic aromatic hydrocarbons (PAH). The estimated additional cost of this TMDL monitoring would be approximately $200-$400 for sampling and $525-$750 for analysis and SMARTS data entry, per sampling location per event. For the Los Angeles Area Lakes TMDL, the waste load allocations for organochlorine pesticides and PCBs are below the analytical reporting limits.

Additionally, the Los Angeles and Long Beach Harbor Waters TMDL waste load allocations for total copper, lead, and zinc are analytically detectible, but limited data from construction site stormwater sampling indicates that compliance with these waste load allocations would be extremely difficult. As further detailed below, because organochlorine pesticides, PCBs, copper, lead, and zinc all bind to sediment and sediment is a common pollutant in stormwater from construction sites that can be managed effectively with BMPs, compliance with these two TMDLs is implemented through a soil screening investigation and, if applicable, a total suspended solids (TSS) numeric effluent limitation detailed in Attachment H, Section I.G.5.

The soil screening investigation is used to determine the presence of the applicable metals, organochlorine pesticides, or PCBs by comparing the concentration of pollutants in the soil to the analytical reporting limit for each substance. The analytical reporting limit is the lowest concentration at which an analyte can be measured in a sample and its concentration can be reported with a reasonable degree of accuracy and precision.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-35
If the analytical reporting limit for any of the TMDL-specific pollutants is exceeded in any soil sample obtained for the soil screening investigation, the Responsible Discharger will be required to sample for TSS as a proxy for the identified TMDL pollutants if the non-visible sampling requirements are triggered. The numeric effluent limitation for TSS is 100 mg/L, and any exceedances require corrective actions detailed in Attachment D, Section III.G and Attachment E, Section III.G.

The value of 100 mg/L TSS is derived from several lines of evidence, including a study where the probability curve between organochlorine pesticides and TSS was modeled to determine that 100 mg/L TSS is protective of water quality when the criteria for 4,4 DDE was 0.00059 mg/L which is equal to the waste load allocation concentrations for chlordane and 4,4 DDT listed in the Los Angeles Area Lakes TMDL. Additionally, a 2018 study found that 100 mg/L TSS correlated with the boundary between particulate and dissolved phase metals in multiple watersheds when the Kd (distribution coefficient) for the metal is 10,000 L/kg.23
I.G.6. Stormwater BMP Selection
a. This General Permit provides dischargers flexibility in selecting the site-specific BMPs necessary to achieve compliance. This flexibility is also provided to Responsible Dischargers in selecting, installing, and maintaining the appropriate BMPs for site-specific situations to meet applicable TMDL requirements, including BMP combinations of:
i. Non-structural BMPs (such as good housekeeping and staff training); ii. Structural source control BMPs (physical, structural, or mechanical devices or BMPs intended to prevent pollutants from entering stormwater) such as erosion control practices, maintenance of stormwater facilities (e.g., cleaning out sediment traps), construction of roofs over storage and working areas, and direction of equipment wash water and similar discharges to the sanitary sewer or other end-use systems; and/or
iii. Structural treatment BMPs which include flow or volume-based treatment BMPs. Structural source control and treatment BMPs usually include a capital investment but are cost-effective compared to removing pollutants 23 Nasrabadi T, Ruegner H, Schwientek M, Bennett J, Fazel Valipour S, Grathwohl P (2018) “Bulk metal concentrations versus total suspended solids in rivers: Time- invariant & catchment-specific relationships.”
Washington Department of Ecology (2004) “A Total Maximum Daily Load Evaluation for Chlorinated Pesticides and PCBs in the Walla Walla River.” Angela Gorgogline, Fabián A. Bomberdelli, Bruno J. L. Pitton, Lorence R. Oki, Darren L. Haver and Thomas M. Young (2018), “Role of Sediments in Insecticide Runoff from Urban Surfaces: Analysis and Modeling.”
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-36
after they have entered stormwater and been discharged into a receiving water body.
b. Stormwater BMP categories for the TMDL pollutant types above are, in general, physical, chemical, hydraulic, and biological. Selection of appropriate site BMPs must be determined based on site-specific factors. No single BMP can achieve the required pollutant reductions for every given situation or pollutant, and each BMP approach has pros and cons. The Responsible Discharger should consider the cost-benefit24 when selecting stormwater BMPs. Some factors include, but are not limited to, upfront-cost, maintenance-cost, pollutant removal efficiency per area/treatment unit, local permitting, site hydrology and geology, safety, space, staffing, and monitoring needs for implementing the BMP(s).

There are many ways to calculate the upfront and maintenance cost of BMPs that consider, for example, BMP sizing, the annual cost for maintenance and/or the annual maintenance hours required.25
Table 1 – University of New Hampshire Stormwater Center26 Select BMP Maintenance Costs and Hours
BMP Maintenance Cost (per
year)
Annual Maintenance
Hours
Bioretention $1,890.00 20.7
Chamber System Not Assessed Not Assessed
Detention Pond $2,380.00 24.0
Gravel Wetland $2,138.00 21.7
Porous Asphalt $1,080.00 6.0
Pervious Concrete $1,080.00 6.0
Retention Pond $3,060.00 28.0
Sand Filter $2,807.00 28.5
I.G.7. Stormwater BMP Categories
24 State of Hawaii Department of Transportation Highways Division. Stormwater Permanent Best Management Practices Manual, page 7-2 Table 1. (February 2007). <http://hidot.hawaii.gov/wp-content/uploads/2015/05/Appx-E.1-Permanent-BMP- Manual-Feb-2007.pdf>. [as of May 20, 2021]. (State of Hawaii BMP Manual) 25 U.S. EPA. Methodology for developing cost estimates for Opti-Tool Memorandum (February 20, 2016), page 8.
<https://www3.epa.gov/region1/npdes/stormwater/tools/green-infrastructure- stormwater-bmp-cost-estimation.pdf>. [as of April 28, 2022]. (U.S. EPA BMP Cost Estimation Memorandum)
26 U.S. EPA BMP Cost Estimation Memorandum, University of New Hampshire Stormwater Center (UNHSC) Select BMP Maintenance Costs and Hours, page 8.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-37
The following categories generally describe currently available types of stormwater BMPs, their expected effectiveness for the TMDL pollutant categories, and some general cost comparisons. The cost comparisons for 6.a-b are based on:
· Staff experience in administering this General Permit for the non-structural and structural source control BMPs;
· The CASQA Industrial and Commercial BMP Handbook for appropriateness of minimum BMPs to control pollutants;
· The CASQA Construction Handbook for appropriateness of minimum BMPs to control pollutants;27 and
· The California Department of Transportation (Caltrans) Construction Site BMP Manual.28
The cost for non-structural controls, which includes good housekeeping, preventative maintenance, spill and leak prevention and response, erosion and sediment controls, employee training programs, and quality assurance and record keeping, is lower than the costs for other BMPs. For example, these costs consist of staff time for training or conducting routine minimum BMP activities and minimal costs for certain materials such as spill kits or for materials for retaining records.

Costs for source control BMPs were estimated generally as being low, medium, or high, dependent on a variety of factors.

The cost comparisons and information in Table 2 for 6.a-i are based on general conclusions from research conducted by the California Stormwater Quality Association, U.S. EPA, U.S. Department of Transportation, State of Hawaii Department of Transportation Highways Division, State of Minnesota Pollution Control Agency, and the Water Environment and Reuse Foundation. State Water Board staff reviewed these sources on:
· The selection of BMPs for general categories of pollutants and performance of pollutant removal;
· The provided upfront costs for a BMP category from a range of low, medium, and high; and
· The provided maintenance costs for a BMP category from a range of low, medium, and high.
27 CASQA Construction BMP Handbook, 2015.
28 California Department of Transportation (Caltrans), Construction Site BMP Manual (May 2017). <https://dot.ca.gov/-/media/dot-
media/programs/construction/documents/environmental-compliance/csbmp-may- 2017-final.pdf> [as of May 20, 2021]
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-38
More specific information on methodology and estimates is available from these sources, which are cited below.
a. Non-Structural BMPs, which include, but are not limited to, site sweeping, staff training and education, dumpster and waste management, routine portable toilet maintenance and cleaning, and proper handling and spill response for construction materials.29 These BMPs can significantly reduce pollutant concentrations in all categories (4.a-g) and can range from low to medium upfront costs depending on the staffing and size of size. In general, operation and maintenance costs are low.
b. Source control BMPs, which include minimizing or eliminating exposure of a pollutant source, can significantly reduce pollutant concentrations in all categories (4.a-g). Upfront costs can range from low (e.g., moving materials or activities indoors or under cover) to high (if, for example, the site must move or build extra covered areas/structures). In general, the operation and maintenance costs are low for exposure minimization and elimination BMPs. c. Bioretention BMPs30 are soil and plant-based filtration structures that reduce runoff velocity and remove pollutants over time through a variety of processes.

Bioretention can significantly reduce pollutant concentrations for categories (4.a), (4.d), (4.e), (4.f), and (4.g) (varies for dissolved metals).31 Usually, costs are medium to high32 per area treated and are tied to proper sizing and design, with low to medium maintenance requirements and cost.33 29 U.S. Department of Transportation (DOT), Federal Highway Administration.

Stormwater Best Management Practices in an Ultra-Urban Setting: Selection and Monitoring. Section 6.5 Table 57. Relative Rankings of Cost Elements and Effective Life of BMP Options.
<https://www.environment.fhwa.dot.gov/Env_topics/water/ultraurban_bmp_rpt/uubmp 6p4.aspx> [as of April 28, 2022]. (U.S. DOT BMP Selection and Monitoring) 30 California Stormwater Association (CASQA), Industrial and Commercial Best Management Practice Online Handbook September 2014, TC-32. <https://www.casqa.org/sites/default/files/casqa-handbook- industrial/full_handbook_2014.pdf> [as of May 20, 2021] (CASQA Industrial and Commercial BMP Handbook)
31 Water Environment and Reuse Foundation (WERF). International Stormwater BMP Database 2020 Summary Statistics Final Report,
<https://www.waterrf.org/system/files/resource/2020-11/DRPT-4968_0.pdf> [as of April 28, 2022]. (International Stormwater BMP Database). 32 State of Hawaii BMP Manual, page 7-2 Table 1.
33 U.S. DOT BMP Selection and Monitoring, section 6.5 Table 57; State of Hawaii BMP Manual, page 7-2 Table 1; U.S. EPA BMP Cost Estimation Memorandum, page 8.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-39
d. Media or Treatment Filtration BMPs34 include either active or passive processes. In passive processes, water flows through treatment media or surface by gravity. In active processes, stormwater flows through media via a pump or similar mechanized system. The media are usually a custom or proprietary blend from the manufacturer and/or vendor (e.g., flocculants, coagulants, carbon, sand, organics). Active systems are chambered and may include pretreatment features to enhance the treatment process. Media filtration can significantly reduce pollutant concentrations categories (4.a), (4.e), and (4.g)35 depending on the specific treatment media. The costs vary significantly depending on the pollutant(s) intended for treatment, the size of the system, and the system design. Upfront costs are generally medium to high per area treated with medium to high maintenance requirements and cost.36 e. Retention BMPs (sediment basin, retention wet pond or extended detention wet pond)37 are constructed basins that have a permanent pool of water most of the year which settle out pollutants and can use plant life to biologically remove pollutants. Retention can significantly reduce pollutant concentrations for all categories but (4.c) and effectiveness for category (4.g) varies depending on the metal and whether the metal is dissolved.38 The upfront and maintenance requirements and costs are tied to proper sizing and design of the system and vary from medium to low.39
f. Detention BMPs (Dry extended detention ponds, dry ponds, extended detention basins, detention ponds, extended detention ponds)40 are basins with designed outlets to achieve a required stormwater draw down time (e.g., 24, 48, or 72 hours). The basins are designed to detain stormwater runoff for some minimum time (e.g., 48 hours) allowing particles and associated pollutants to settle. These basins have a temporary wet pool dependent on the infiltration rate of the subsoil. Detention can significantly reduce pollutant concentrations 34 CASQA Industrial and Commercial BMP Handbook, TC-40 Media Filter. 35 CASQA Industrial and Commercial BMP Handbook, TC-40 Media Filter. 36 State of Hawaii BMP Manual, page 7-2 Table 1; U.S. DOT BMP Selection and Monitoring, section 6.5 Table 57; U.S. EPA BMP Cost Estimation Memorandum, page

8. 37 CASQA Industrial and Commercial BMP Handbook, TC-20 Wet Pond. 38 WERF International Stormwater BMP Database 2016 Summary Report. 39 State of Hawaii BMP Manual, page 7-2 Table 1; U.S. DOT BMP Selection and Monitoring, section 6.5 Table 57; U.S. EPA BMP Cost Estimation Memorandum, page

8. 40 CASQA Industrial and Commercial BMP Handbook, TC-22 Extended Detention Basins.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-40
for all categories except for (4.c) and (4.g), though detention’s effectiveness for metals is variable depending on the metal and whether the metal is dissolved.41 The upfront and maintenance requirements and costs are tied to proper sizing and design of the system and vary from medium to low.42 g. Wetland BMPs (constructed wetlands)43 are constructed basins with a permanent pool of water for most of the year and are shallower with more vegetation than wet ponds. Stormwater is stored in the shallow pools of vegetation. Pollutant removal is achieved through microbial transformation, plant uptake, settling, and adsorption. Pretreatment is suggested to reduce the needed annual maintenance by reducing the amount of sediment and other solids entering the BMP. Wetlands can significantly reduce pollutant concentrations for all categories except for (4.b) and (4.c).44 The upfront costs are medium to high, and the operation and maintenance costs and requirements are medium.45
h. Infiltration BMPs (volume reduction)46 are trenches or basins which store stormwater in the void space between the media (e.g., rock, stones, soil media) and infiltrates/exfiltrates through the bottom and sides into the ground.

Infiltration reduces stormwater discharge volume and pollutant loadings to surface waters and can recharge groundwater aquifers or be used for other appropriate purposes and provide cost-savings by offsetting the use of potable water (e.g., cooling towers and equipment cleaning water). Pretreatment is necessary to limit the amount of gross pollutants, oil & grease, and sediment to the system to ensure the system functions properly. Infiltration can significantly reduce pollutant concentrations for all categories, however, in all cases fate and transport of pollutants to groundwater should be evaluated for impacts to drinking water beneficial uses (e.g., salts, solvents). The upfront and 41 WERF International Stormwater BMP Database 2016 Summary Report. 42 State of Hawaii BMP Manual, page 7-2 Table 1; U.S. DOT BMP Selection and Monitoring, section 6.5 Table 57; U.S. EPA BMP Cost Estimation Memorandum, page

8. 43 CASQA Industrial and Commercial BMP Handbook, TC-21 Constructed Wetlands. 44 WERF International Stormwater BMP Database 2016 Summary Report. 45 State of Hawaii BMP Manual, page 7-2 Table 1; U.S. DOT BMP Selection and Monitoring, section 6.5 Table 57; U.S. EPA BMP Cost Estimation Memorandum, page

8. 46 CASQA Industrial and Commercial BMP Handbook, TC-10 Infiltration Trench and TC- 11 Infiltration Basin.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-41
maintenance costs and requirements are tied to proper sizing and design of the system and are medium.47
Table 2 – Effective BMP Examples for TMDL Pollutant Categories48 Best
Manage-
ment
Practice
Bac-
teria
(4.a)
Chloride
and
Salts
(4.b)49
Dia-
zinon
(4.c)
Nutrients
(4.d)
Sediment
(4.e)
Temper-
ature
(4.f)
Toxics
and
Metals
(4.g)50
Non-
Structural
and
Exposure
Minimi-
zation

X X X X X X X
Bioreten-
tion
Devices

X X X X X
Media or
Treatment
Filtration
X X X
Retention
Basins/
Ponds

X X X X X X
Detention
Basins/
Ponds

X X X X X
Construct-
ed
Wetlands

X X X X X
Infiltration
or Volume
Reduction

X X X X X X
47 State of Hawaii BMP Manual, page 7-2 Table 1; U.S. DOT BMP Selection and Monitoring, section 6.5 Table 57; U.S. EPA BMP Cost Estimation Memorandum, page

8. 48 WERF International Stormwater BMP Database 2016 Summary Report. Also see Table 2 footnotes 47 and 48.
49 Not evaluated in the WERF International Stormwater BMP Database 2017 Summary and is based upon guidance from the Minnesota 2015 Industrial Stormwater BMP Handbook.
50 From CASQA TC-10 and TC-11 not evaluated in the WERF International Stormwater BMP Database 2017 Summary.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-42
I.H. Rationale
I.H.1. General Permit Approach
A General Permit for construction activities over one acre is an appropriate permitting approach for the following reasons:
a. A General Permit is an efficient method to establish the essential regulatory requirements for a broad range of construction activities under differing site conditions;
b. A General Permit is the most efficient method to handle the large number of construction stormwater permit applications;
c. A General Permit application process for coverage is far less onerous than that for individual permit and hence more cost effective;
d. A General Permit is consistent with U.S. EPA's four-tier permitting strategy, the purpose of which is to use the flexibility provided by the Clean Water Act in designing a workable and efficient permitting system; and e. A General Permit is designed to provide coverage for a group of related facilities or operations of a specific industry type or group of industries. It is appropriate when the discharge characteristics are sufficiently similar, and a standard set of permit requirements can effectively provide environmental protection and comply with water quality standards for discharges. In most cases, the general permit will provide sufficient and appropriate management requirements to protect the quality of receiving waters from discharges of stormwater from construction sites.

There may be instances where a General Permit is not appropriate for a specific construction project. A Regional Water Board may require any discharger otherwise covered under this General Permit to apply for and obtain an individual permit or apply for coverage under a more specific General Permit. The Regional Water Board must determine that this General Permit does not provide adequate assurance that water quality will be protected, or that there is a site-specific reason why an individual permit should be required.

There may be other permits or requirements in addition to this General Permit. For example, the discharger may also need a streambed alteration agreement from the California Department of Fish and Wildlife, a Water Quality Certification (CWA § 401) as administered by the State and Regional Water Boards, CWA § 404 permit administered by the U.S. Army Corp. of Engineers, and/or a permit for low threat or de minimis discharges. Contact the appropriate Regional Water Board(s) to determine if other permits are required for the construction activity.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-43
I.H.2. Antidegradation Findings
Federal regulations at 40 Code of Federal Regulations § 131.12 require that state water quality standards include an antidegradation policy consistent with federal requirements. The State Water Board established California’s antidegradation policy in State Water Board Resolution No. 68-16 (“Statement of Policy with Respect to Maintaining High Quality of Waters in California”). Where the federal antidegradation policy is applicable, the State Water Board has interpreted Resolution No. 68-16 to incorporate the federal antidegradation policy.51 The permitted discharge must be consistent with the antidegradation provision of 40 Code of Federal Regulations § 131.12 and State Water Board Resolution No. 68-

16. The State Water Board finds that the permitted discharges authorized by this general NPDES permit are consistent with the antidegradation provisions of 40 Code of Federal Regulations § 131.12 and State Water Board Resolution No. 68- 16, as set forth herein.

In the context of this general NPDES permit, compliance with the federal antidegradation policy requires consideration of the following. First, the State Water Board must ensure that “existing instream uses and the level of water quality necessary to protect the existing uses” are maintained and protected.52 Second, if the baseline quality of a waterbody for a given constituent “exceeds levels necessary to support propagation of fish, shellfish, and wildlife and recreation in and on the water,53 that quality shall be maintained and protected” through the requirements of this general NPDES permit unless the State Water Board makes findings that: (1) any lowering of the water quality is “necessary to accommodate important economic or social development in the area in which the waters are located”; (2) “water quality adequate to protect existing uses fully” is assured; and (3) “the highest statutory and regulatory requirements for all new and existing point sources and all cost-effective and reasonable best management practices for nonpoint source control” are achieved.54 Before allowing any lowering of high quality water, the Board must conduct an analysis of alternatives that evaluates practicable alternatives that would prevent or lessen the degradation associated with the discharges permitted. In the context of 40 Code of Federal 51 State Water Board Order WQ 86-17 (Fay), pages 16-19. 52 State Water Board, Administrative Procedures Update, Antidegradation Policy Implementation for NPDES Permitting, 90-004 (APU 90-004), page 4. 40 Code of Federal Regulations § 131.12(a)(1). This provision has been interpreted to mean that, “[i]f baseline water quality is equal to or less than the quality as defined by the water quality objective, water quality shall be maintained or improved to a level that achieves the objectives.”
53 This discussion refers to such waters as “high quality waters.” 54 40 Code of Federal Regulations § 131.12(a)(2).

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-44
Regulations § 131.12(a)(2)(ii), practicable means “technologically possible, able to be put into practice, and economically viable.”55
The permit must also comply with any requirements of State Water Board Resolution No. 68-16 beyond those imposed through incorporation of the federal antidegradation policy.56 Resolution No. 68-16 requires that high quality waters be maintained unless degradation is justified based on findings that any lowering of water quality is “consistent with the maximum benefit to the people of the State” and “will not unreasonably affect present and anticipated beneficial use of such water and will not result in water quality less than that prescribed in the policies” and further that the discharge is subject to “waste discharge requirements which will result in the best practicable treatment or control of the discharge.”57 The baseline quality considered in making the appropriate findings is the best quality of the water since 1968, the year of adoption of Resolution No. 68-16, or a lower level if that lower level was allowed through a permitting or other regulatory action, such as establishing a water quality objective, that was consistent with the federal and state antidegradation policies.58 The following analysis assumes, without deciding, that the baseline for antidegradation analysis is 1968.59 55 40 Code of Federal Regulations § 131.3(n).
56 State Water Board Order No WQ 86-17 (Fay), page 23, Finding No. 11 57 State Water Board Orders WQ 81-5 (City of Lompoc), WQ 82-5 (Chino Basin Municipal Water District), WQ 90-6 (Environmental Resources Protection Council).

State Water Board Resolution 68-16, Resolve 2. Best practicable treatment or control is not defined in Resolution 68-16; however, the State Water Board has evaluated what level of treatment or control is technically achievable using “best efforts.” Questions and Answers, State Water Board Resolution 68-16, (Feb. 16, 1995), pp. 5-

6. The State Water Board states: “To evaluate the best practicable treatment or control method, the discharger should compare the proposed method to existing proven technology; evaluate performance data, e.g., through treatability studies; compare alternative methods of treatment or control; and/or consider the method currently used by the discharger or similarly situated dischargers...The costs of the treatment or control should also be considered....”
58 State Water Board APU 90-004, page.4. The baseline for application of the federal antidegradation policy is 1975, which is the date used in 40 Code of Federal Regulations § 131.3(e) to define existing uses of a waterbody. For state antidegradation requirements, see also Asociacion de Gente Unida por el Agua (AGUA) v. Central Valley Water Board (2012) 210 Cal.App.4th 1255,1270. The baseline for the application of the state antidegradation policy is generally the highest water quality achieved since 1968, the year the policy was adopted. 59 State Water Board Resolution 68-16, Resolve 1. The baseline may be later than 1968 for two reasons. First, the appropriate baseline is determined by the date on which a ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-45
a. The Board Is Not Required to Make Waterbody by Waterbody and Pollutant by Pollutant Antidegradation Findings
The State Water Board finds that it is not required to conduct a waterbody by waterbody and pollutant by pollutant antidegradation analysis for this permit.

The State Water Board makes this finding for two reasons. First, the Administrative Procedures Update, Antidegradation Policy Implementation for NPDES Permitting, 90-004 (APU 90-004), which specifies a waterbody by waterbody and pollutant by pollutant analysis for some permitting actions, does not address permitting for diffuse stormwater discharges. Second, APU 90-004 itself indicates that a waterbody by waterbody and pollutant by pollutant analysis is only required when conducting a “complete” antidegradation analysis; a complete analysis, in turn, is not required where any “reduction in water quality is temporally limited and would not result in any long-term deleterious effects on water quality.”60 As detailed below in the section regarding waters that do not meet water quality objectives and in Alternative 1, a complete analysis is not required. The discussion below elaborates on these two reasons.

APU 90-004 is a State Water Board internal guidance document establishing methods for implementing the federal and state antidegradation policies in NPDES permits. APU 90-004 suggests that an antidegradation analysis requires a pollutant by pollutant and waterbody by waterbody analysis in certain contexts, specifically where the discharge at issue is a discrete discharge from a singular facility, such as discharges from publicly owned treatment works.

However, APU 90-004 has limited value when considering antidegradation in the context of diffuse stormwater discharges from tens of thousands of future construction projects of a wide variety distributed throughout the entire state over the life of the permit, each with the potential for discharging multiple policy establishing the level of water quality to protect was effective.

State Water Board APU 90-004, page 2. The various water quality control plans and State Policies for Water Quality Control have been adopted and amended many times since the 1970’s to include new or revised water quality objectives. Second, a permitting action with appropriate antidegradation findings allowing degradation may establish a new baseline consistent with the level of water quality achieved under that permit. The State Water Board has regulated construction stormwater discharges in the past through general permits issued in 1999 and 2009. APU 90-004 acknowledges that no antidegradation analysis is required where the water board has no expectation that water quality will be reduced by the permitting action; here, if the water quality achieved under the prior general permits had been used as the baseline, arguably, no antidegradation analysis would have been required. Nevertheless, for ease of analysis, 1968 is used herein as the baseline.
60 State Water Board APU 90-004, page 2.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-46
pollutants, to a wide variety of waterbodies statewide.61 This interpretation is sensible, if not necessary, for this general NPDES permit, given the short-term nature of construction projects and the fact that, as of the date of adoption of this permit, the type and location of the construction projects that will be regulated by this General Permit is unknown. Therefore, only a generalized antidegradation analysis can, and must, be conducted for the discharges authorized by this general NPDES permit.

In addition, reliable data on the baseline water quality since 1968 is not available for all pollutants for all surface waters of the state that might receive discharges authorized by this General Permit. The State Water Board did not begin conducting statewide assessments of water quality until 1973. That first assessment was based only on very limited sampling for only five water quality parameters on portions of 23 water bodies. Over the course of the next five decades, those assessments have gradually become more comprehensive and thorough, culminating with the State Water Board’s most recent 2020-2022 Integrated Report, which assessed the waterbodies for three of the nine Regional Water Quality Control Boards. However, even though a large amount of ambient water quality data is now collected and evaluated for these biennial assessments, the integrated reports are focused on assessing whether the waterbodies are supporting beneficial uses. The assessments are not intended to provide information about whether the waterbodies are of a higher quality than necessary to support their beneficial uses.62 As a result, this analysis assumes that some of the waterbodies that will receive stormwater discharges from some of the construction sites are high quality waters with respect to at least some pollutants that might be in the authorized discharges. Due to the wide variety and unknown identity of the large number of potential waterbodies that might receive authorized discharges from construction projects under this permit and the lack of specific, reliable data regarding each potential receiving waterbody, the analysis of waterbodies that might be affected by this general NPDES permit must also be done at a generalized level.

The State Water Board additionally finds that, even if APU 90-004 applies to the issuance of this permit, it requires at most a “simple” antidegradation analysis. APU 90-004 contemplates that a “simple” antidegradation analysis is 61 State Water Board Order WQ 2018-0002, page 77. Reaches a similar conclusion for agricultural discharges. This is even more so for the discharges authorized by this Order, because, unlike discharges from agricultural lands, there is much more uncertainty as to the location of the future construction projects and the temporal nature of discharges of stormwater from construction sites. 62 Regional Water Quality Control Boards Biennial Assessments. <https://www.waterboards.ca.gov/water_issues/programs/water_quality_assessment> [as of July 19, 2022]
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-47
appropriate under specified circumstances. In particular, as stated above, APU 90-004 states that a simple antidegradation analysis is allowed when the “[Water] Board determines the reduction in water quality is temporally limited and will not result in any long-term deleterious effects on water quality; e.g., will cease after a storm event is over.”63
APU 90-004 does not provide guidance on the scope and content of a simple antidegradation analysis. Nor does it define the terms “temporally limited” or “long term.” Those terms must therefore be interpreted in the context of the types of discharges being permitted and with deference to the best professional judgment of the State Water Board. Construction stormwater discharges fit within the example provided by the APU and are temporal and inherently short- term. Therefore, any degradation would be temporally limited and would not result in long-term deleterious effects on water quality. In addition, the permit continues the requirements of the previous permits or imposes equivalent or more protective requirements such that, in at least at a generalized level, the water quality established under the prior permits is expected to be maintained and improved.

The State Water Board determines that the findings made below meet the requirements of a simple antidegradation analysis and are also consistent with an antidegradation analysis done at a generalized level, as appropriate for this permit. With these findings, based on the information available to it and using its best professional judgment, the State Water Board concludes that the discharge will not be adverse to the intent and purpose of the State and federal antidegradation policies. Regardless of APU 90-004’s application, however, the below analysis is consistent with the generalized antidegradation analysis appropriate for this general NPDES permit and complies with both the federal antidegradation regulations, and with the State antidegradation policy. b. The State Water Board Makes the Following Antidegradation Findings The discharges permitted in the permit are consistent with the antidegradation provisions of 40 Code of Federal Regulations § 131.12 and Resolution No. 68-

16. The State Water Board’s conclusion that the terms and conditions of the permit are consistent with the antidegradation policies is based on the following analysis.

First, for waterbodies that meet, but do not exceed, the water quality objective for a particular pollutant, no antidegradation findings are required. For these waterbody and pollutant combinations, compliance with the General Permit’s requirements ensures that all construction stormwater discharges authorized by 63 State Water Board APU 90-004, p. 2
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-48
this permit do not interfere with the maintenance and protection of existing beneficial uses and water quality objectives.
i. Waterbodies that do not meet water quality objectives (waterbodies that are not high quality)
Because coverage under this General Permit is available statewide, this General Permit authorizes discharges to at least some surface waters that are not meeting water quality objectives. Some of these waterbodies are listed on the State Water Board’s section 303(d) list of impaired waters, some of which have applicable TMDLs developed by the Regional Water Boards or U.S. EPA.64 Some receiving waters are not meeting water quality objectives for multiple pollutants. Under both federal and state antidegradation policies, these receiving waters are not considered “high quality” waters for these pollutants. For receiving waters that are not high quality waters, the federal antidegradation policy requires that regulatory actions ensure that existing instream uses and the level of water quality necessary to protect the existing uses are maintained and protected. (40 Code of Federal Regulations § 131.12(a)(1).)65 The General Permit ensures that existing instream (beneficial) uses and the level of water quality necessary to protect the existing uses are maintained and protected through requirements that discharges authorized by this General Permit do not cause or contribute to exceedances of water quality objectives in the receiving water and to restore impaired waterbodies by requiring compliance with TMDL-specific requirements as set forth in Attachment H and compliance with receiving water limitations set forth in the General Permit, Section IV.D. These provisions are collectively designed to ensure that discharges authorized by this General Permit do not cause any further degradation of impaired waterbodies and do not interfere with the improvement of the quality of such waters to a level protective of existing uses over a time schedule that is as short as possible.

The antidegradation policies do not explicitly or implicitly override the authority and discretion the Clean Water Act and the Water Code grant to the State Water Board as to how it structures a permit to ensure water 64 Impaired waters, or waters that are not high quality, are not confined to those listed only on the 303(d) List. There are several reasons for this, including but not limited to that some of the 303(d) Lists do not reflect current data. In addition, sometimes the State lacks sufficient data to add a waterbody to the 303(d) List. Accordingly, the 303(d) List itself does not reflect all waterbodies that are impaired. 65 By its terms, State Water Board Resolution No. 68-16 does not separately apply to waters that are not high quality, except by incorporating the federal antidegradation policy as discussed above.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-49
quality necessary to protect beneficial uses. The law does not require immediate restoration of impaired waterbodies nor does it require an immediate prohibition of discharges that contribute to an exceedance in the waterbody. Rather, federal regulations at 40 Code of Federal Regulations § 122.47 allow NPDES permits to have compliance schedules. Similarly, Water Code § 13263, subdivision (c), authorizes the Regional Water Boards to include a time schedule for achieving water quality objectives in waste discharge requirements. Consistent with Water Code § 13242, TMDL implementation plans, as incorporated into the water quality control plans, include a time schedule for actions to be taken. When issuing waste discharge requirements, Water Code § 13263 requires Regional Boards to implement any relevant water quality control plans that have been adopted.

Certainly, water quality objectives must be achieved; but the law, as cited above, recognizes and allows for the fact that it can take time to restore or achieve the objectives. In this regard, some impaired waterbodies may fail to improve or, rarely, continue to degrade, for a period of time before showing improvement. This period of time may be as long as multiple years.

This is not contrary to the authorities for compliance schedules stated above and is not contrary to the antidegradation policies.
ii. High quality waterbodies
Some of the waterbodies within the area covered by this General Permit may be high quality waters for certain pollutants. Some of these waterbodies may be currently high quality as compared to currently applicable objectives. Others of these waterbodies may be currently impaired but may be classified as high quality waters because they were historically high quality for certain pollutants.

Although compliance with the General Permit will generally not result in degradation in high quality waters, compliance with the General Permit does not guarantee that there could never be any degradation in any high quality waters from a specific construction project. Therefore, the State Water Board makes the following findings to comply with antidegradation requirements for any discharges authorized by this General Permit to high quality waters.

For high quality waterbodies, the State Water Board finds as follows:

First, to determine whether the discharge is necessary, the State Water Board must determine whether there are any cost-effective alternatives available that eliminate or reduce the reduction in water quality. For a general, statewide permit, the appropriate inquiry is whether there are cost- effective alternatives to the regulatory framework in the General Permit, not whether there is a cost-effective alternative to an individual project eligible for enrollment under the General Permit. The State Water Board has ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-50
determined that construction stormwater discharges are appropriately regulated under a general permit rather than individual NPDES permits.

There are typically approximately 10,000 ongoing construction projects with stormwater discharges authorized under this General Permit (or its predecessor general permits) at any given time, according to the State Water Board’s SMARTS database. These projects typically last from one to three years, at which point coverage under this General Permit is terminated and discharges are no longer authorized. Employing the large number of additional staff necessary to review and issue such a high volume of individual stormwater permits would not be efficient use of resources, would necessitate very large increases in permit fees under Water Code § 13260, subdivision (d)(1)(B) to pay for the additional staff, and would likely result in economic disruption due to delays in permitting construction projects. As further explained in Fact Sheet, Section I.H.1, a General Permit is the appropriate mechanism to regulate a large number of similar discharges while still protecting water quality.

Practicable Alternatives: The State Water Board has evaluated a range of practicable alternatives that would prevent or lessen any degradation associated with permitted construction stormwater discharges to high quality waters. These alternatives are discussed below.

Alternative 1 – The first alternative is the approach that the General Permit takes. The General Permit requires dischargers, with the assistance of qualified stormwater professionals, to:
1) Determine the risk the construction project poses on the receiving water, based on how much sediment is anticipated to be discharged offsite and whether the receiving water is impaired for sediment or supports COLD, SPAWN, and MIGRATORY beneficial uses. Higher risk projects must comply with additional permit requirements, including sampling and monitoring, and additional BMPs.
2) Assess conditions at the construction site that could impact stormwater quality such as sources of pollutants that could be transported offsite by stormwater runoff.
3) Develop a site-specific Stormwater Pollution Prevention Plan to include information needed to demonstrate compliance with all requirements of the permit and to ensure water quality is protected (Fact Sheet, Section I.V.). This includes identification and implementation of a suite of best management practices tailored to the construction project and the conditions at the site to minimize or eliminate the stormwater discharges, or the pollutants in the stormwater discharges, or both, in compliance with BCT/BAT/BPT standards.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-51
4) Visually inspect the construction site to verify implementation of best management practices is in accordance with the Stormwater Pollution Prevention Plan.
5) Monitor stormwater discharges for pH and turbidity during each day of a qualifying precipitation event and compare sample results to numeric action levels to verify that implementation of the best management practices is protective of water quality.
6) Monitor stormwater discharges for TMDL-specific pollutants, if applicable, and compare to a TMDL-related numeric action level or numeric effluent limitation to verify that the discharge complies with the TMDL-based waste load allocations. TMDL monitoring requirements apply if the site is in a TMDL watershed with waste load allocations translated into numeric action levels or numeric effluent limitations; has sources of the TMDL-specific pollutant(s) onsite; and there is a failure to implement best management practices, a container spill or leak, or a best management practices breach, failure, or malfunction. 7) Take corrective actions such as repairing or implementing additional best management practices, if visual inspections and discharge monitoring indicate a deficiency.
8) Submit sampling and annual reports regarding implementation of this General Permit.

All discharges authorized by this General Permit must comply with receiving water limitations that require that discharges 1) do not adversely affect human health or the environment, 2) do not contain pollutants in quantities that threaten to cause pollution or public nuisance, 3) do not contain pollutants that cause or contribute to an exceedance of any applicable water quality objectives or standards contained within an applicable water quality control plan, and 4) comply with the applicable TMDL implementation requirements of this General Permit (Order, Section IV.D). Furthermore, the Regional Water Boards retain the authority to impose any additional site- specific requirements where necessary to prevent degradation and to protect water quality standards.

Under this General Permit, there are disincentives to discharging such that dischargers already seek to minimize or eliminate their stormwater discharges where possible. The General Permit promotes efforts to maximize the capture of stormwater from construction sites through retention basins, infiltration galleries, and other controls that reduce the amount of stormwater that is discharged from the site. If there are no discharges, the General Permit’s sampling requirements and any otherwise applicable numeric action levels or numeric effluent limitations are not ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-52
applicable to that discharger and the discharger would not risk an enforcement action for any potential discharge-related General Permit violations. Accordingly, dischargers have an incentive to schedule their work during dry weather or to retain stormwater whenever possible. Collectively, these requirements generally prevent degradation, and where that is not possible, minimize degradation and the duration of any degradation. This alternative does not, however, guarantee that no construction site will ever have authorized stormwater discharges that may result in temporary, limited degradation.

Alternative 2 – The second alternative would be more stringent permit requirements in watersheds with high quality waters. Different approaches for more stringent requirements could include a construction prohibition, a prohibition of discharges, a requirement that active treatment be used for all pollutants in all stormwater discharges, or numeric effluent limitations for all pollutants in all stormwater discharges.

The State Water Board finds that more stringent requirements are not currently possible for any of these approaches for the following reasons:
· Construction prohibition: Such a prohibition would exceed the State Water Board’s authority to regulate discharges of waste to waters of the state from discharges. The State Water Board does not have the authority to directly regulate land use. (Wat. Code, §§ 13260, 13263.) Such a prohibition is also not possible because many construction projects are essential and cannot be relocated (e.g., repair of existing roads and utilities).
· Prohibition on discharges: By eliminating all stormwater discharges, pollutants from stormwater would not reach high quality receiving waters during wet weather and therefore could not cause any degradation. As wet weather will always occur, this approach would require all construction sites to retain all stormwater through retention basins, infiltration galleries, and other controls that would prevent stormwater from reaching surface waters through infiltration, evaporation, or storage and reuse. The complete retention to eliminate any possibility of discharge is not typically technologically or economically feasible in many locations. Although retention, detention, and run-on BMPs are frequently implemented as part of the SWPPP, these BMPs are typically designed only to reduce stormwater discharges or the likelihood thereof, not to completely eliminate discharges. Retention that eliminates the possibility of discharges to any surface waters would require much larger sizing than a retention or detention BMP used to reduce discharges because it would need to be sized to capture even extreme weather ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-53
events.66 U.S. EPA estimated that the base cost, which does not include costs of acquiring the land,67 annual maintenance costs, design, geotechnical testing, legal fees, land costs, and other unexpected or additional costs such as fees for disposing of contaminated excavated soils, for a retention and detention basins is $0.50-$1.00 per cubic foot.68 The estimate of typical costs reflects 15,000 – 150,000 cubic feet of storage. Thus, a retention basin for a 50-acre residential site would have the base cost of $100,000. But this base cost only represents the typical implementation of stormwater BMPs, which only provide for detention or partial retention. A retention basin for a 50-acre residential site that eliminated the possibility of discharge would need to be much larger and therefore is more costly. Most California counties require stormwater basins to be designed to a 2-year, 24-hour storm intensity at minimum.

Assuming a typical bare soil runoff coefficient of 0.35 (Type C soil), a 2- year, 24-hour storm (2.27 inches of rainfall) at a 50-acre site in Orange County, for example, would produce a total of approximately 3.31 acre- feet of runoff per day. Adding a normal Factor of Safety for detention structures of 2.0, 5,770 cubic feet of water would need to be retained per acre, or 288,400 cubic feet for the entire parcel. An ‘atmospheric river’ type storm that lasted three days at this intensity would require at least six times this amount of storage, as the runoff coefficient would increase each day. The costs would vary significantly depending on land costs (e.g., urban versus rural area) and slope. Complete retention of all stormwater would not be technologically feasible at all construction sites. 66 For example, in October 2021, there were historic Category 5 atmospheric rivers throughout California.
67 The cost of acquiring land can be substantial.

E.g. Working Paper 19-01: The Price of Residential Land for Counties, ZIP codes, and Census Tracts in the United States.,
<https://www.fhfa.gov/PolicyProgramsResearch/Research/Pages/wp1901.aspx> [as of July 19, 2022]. For example, in Los Angeles County, residential land costs were estimated at $1-3 million per acre. Id.

See also, Southern California Coastal Water Research Project. Concept Development: Design Storm for Water Quality in the Los Angeles Region, Technical Report 520. October 1, 2007, page 7.
<https://ftp.sccwrp.org/pub/download/DOCUMENTS/TechnicalReports/520_designSto rm.pdf> [as of July 19, 2022].
68 U.S. EPA Urban Storm Water BMP Preliminary Data Summary - 1999, page 6-3. <https://www.epa.gov/sites/default/files/2015-11/documents/urban-stormwater- bmps_preliminary-study_1999.pdf> [as of July 19, 2022]. Other costs could include, for example, filling, regrading, and vegetating the retention pond after the construction project has concluded.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-54
Certain sediment types are poorly suited for infiltration (e.g., clay soils infiltrate poorly). Construction sites are inherently dynamic, but retention basins cannot move. Stormwater may have different discharge points during different phases of construction, and a retention basin could not be moved to accommodate the changing points. In urban areas with infill development, there is not sufficient space for such large retention basins. In some cases, such large basins could also implicate vector control or public safety issues.69 In other areas where the groundwater table is high, it may not be possible to design an effective retention basin without hitting the groundwater table and potentially causing groundwater quality problems.

Even if complete retention were technologically possible, the costs associated with constructing effective complete retention structures are not generally economically feasible for most construction projects.70 Expensive, structural BMPs are generally not economically feasible to implement on construction sites, which are temporary in nature, in part because the useful life of the investment is short-term and difficult to recoup. Requiring implementation of substantially more expensive controls may render projects that are beneficial to the people of the state economically infeasible. For example, government-funded road projects often operate on fixed budgets where increased costs on one construction project leaves less money to complete other projects.71 Similarly, restoration projects are frequently funded by grants. Increased construction costs would render less money available for additional restoration projects. Increased construction 69 Southern California Coastal Water Research Project. Concept Development: Design Storm for Water Quality in the Los Angeles Region, Technical Report 520. October 1, 2007, page 7.
<https://ftp.sccwrp.org/pub/download/DOCUMENTS/TechnicalReports/520_designSto rm.pdf> [as of July 19, 2022]. Notes the potential trade-offs between water quality and ensuring public safety, including protecting property from flood damage and maintaining passable roadways.
70 Southern California Coastal Water Research Project. Concept Development: Design Storm for Water Quality in the Los Angeles Region, Technical Report 520. October 1, 2007, p. 14.
<https://ftp.sccwrp.org/pub/download/DOCUMENTS/TechnicalReports/520_designSto rm.pdf> [as of July 19, 2022]. Provides an example. Discusses the feasibility of BMP implementation costs in the Ballona Creek watershed and highlighting the difference between new or redevelopment versus retrofit.
71 Overview of Transportation Funding (2015).
<https://lao.ca.gov/handouts/transportation/2015/Transportation-Funding-022315.pdf> [as of July 19, 2022]. For example, general obligation bonds can help pay for transportation projects and are for a set amount.

Carlsbad City CouncilOctober 21, 2025

Carlsbad City Council
October 21, 2025