City Plaza Residential (TPM ) Preliminary Hydrology Report

Hydrology Study City Plaza Residential (TPM 2016-127) Preliminary Hydrology Report Orange, Orange County, California Prepared For: Greenlaw Partners 18301 Von Karman Avenue, Suite 250 Irvine, CA 92612 Prepared By: Contact Person: Scott P. Gilbert, P.E. MBI JN 151623 July 18, 2016 D1-1

City Plaza Residential Orange, CA Preliminary Hydrology Report Table of Contents Section 1 - Introduction... 3 1.1 General Introduction... 3 Section 2 Design Criteria... 5 Section 3 Hydrology... 6 3.1 Watershed Description and Drainage Patterns... 6 3.2 Land Use Development... 6 3.3 Precipitation... 6 3.4 Infiltration and Soils... 7 3.5 Watershed Model Development... 7 3.6 Design Hydrology... 7 Section 3 - Results... 8 3.1 Existing Hydrology Results... 8 3.2 Proposed Hydrology Results... 8 3.3 Conclusion... 8 Appendix A: Existing Hydrology Calculations & Map Appendix B: Proposed Hydrology Calculations & Map Appendix C: Reference Materials 2 D1-2

City Plaza Residential Orange, CA Preliminary Hydrology Report Section 1 - Introduction 1.1 General Introduction The 8.62 acre site is located at 1 City Boulevard in Orange, California which is situated southwest of the Block of Orange development along City Boulevard. The project site, designated land use Urban Mixed Use, is bounded by the parking lots to the north, to the south, City Boulevard to the east, and South Lewis Street to the West. The site is relatively level with an approximate maximum elevation difference of 2 feet sloping down to the southwest. Currently, the site is developed with a multi-story commercial building situated on the southeastern portion of the site. The site is bounded on all sides with asphalt parking, drive aisles, and roadways. Some minor landscaping is present along the property lines and within the parking aisles. The proposed development will consist of a 5-story residential building wrapped around a 7-story parking structure and an additional 6.5-level parking structure is proposed toward the central portion of the property, where one level of parking is below grade for this structure. The existing multi-story commercial building will be preserved in the southeastern portion of the site while the remaining areas will become access roads to these elements. Proposed drive aisles will utilize a combination of asphalt and concrete pavers while common areas will utilize concrete, turf, and landscaping. Waste generated will be typical of a residential and commercial community. Some amenities included are a pool deck, pool building, lobby, and a courtyard located central to the wrapped buildings. VICINTY MAP 3 D1-3

City Plaza Residential Orange, CA Preliminary Hydrology Report The primary objectives of this report are as follows: 1. Perform ultimate condition hydrologic analysis considering ultimate condition land uses for City Plaza Residential. A computer hydrologic model will be developed based on drainage patterns, ground slope, ultimate condition land use, and soil type using methodology from the Orange County Hydrology Manual. 4 D1-4

City Plaza Residential Orange, CA Preliminary Hydrology Report Section 2 Design Criteria This study has been prepared in conformance with the hydrological procedures and standards set forth in the Orange County Hydrology Manual, dated 1986 (including 1996 addendum). Existing condition drainage area delineation was performed utilizing survey shots for the site. Proposed condition drainage areas were developed using proposed street elevations and grades, pad elevations and proposed storm drain layout. Due to the size of the watershed (less than 640 acres), only rational method was used to calculate the peak runoff at each concentration point. 10-year and 25-year frequency storm events were used to determine the peak flow for storm drain sizing. The streets will be designed such that the 100-year frequency will be conveyed in the proposed street right of way. Point precipitation values for the 10-year 1-hour, 25-year 1-hour and 100- year 1-hour, used in the rational method analysis, were per the NOAA Atlas 14, Volume 6, Version 2. The antecedent moisture condition (AMC) used was AMC II for the 10-year and 25-year and AMC III for the 100-year analysis. City Plaza Residential land use for the ultimate condition was utilized for the entire tributary area. 5 D1-5

City Plaza Residential Orange, CA Preliminary Hydrology Report Section 3 Hydrology Stormwater runoff is a function of watershed characteristics, precipitation, infiltration, and routing processes. Each of these topics is discussed briefly in the following paragraphs. City Plaza Residential drainage study follows methods and procedures found in the Orange County Hydrology Manual. 3.1 Watershed Description and Drainage Patterns Post development drainage will mimic the existing condition drainage. From a drainage standpoint, the existing site is currently providing runoff to a private storm drain located along Lewis Street, where it then enters the East Garden Grove Wintersburg Channel before ultimately reaching the outlet point in Huntington Harbor. 3.2 Land Use Development City Plaza Residential consists of two commercial building with surrounding parking lot. While the existing condition is considered commercial land use, for a more conservative existing condition the land use combination of public park and commercial was used to more accurately depict the 88% imperviousness of the site. The ultimate condition hydrology was performed utilizing the proposed land use of apartment, which represents an impervious value of 80% which accurately represents the imperviousness of the proposed site in the ultimate condition. 3.3 Precipitation The precipitation analysis for the study area was based upon the NOAA Atlas 14 volume 6, version 2 at latitude 33.7811, and longitude -117.8941 (see Appendix C, Reference Materials). The 1-hour precipitation depths for City Plaza are 0.829 inches, 1.02 inches and 1.31 inches for 10-year, 25-year and 100-year storm events, respectively. 6 D1-6

City Plaza Residential Orange, CA Preliminary Hydrology Report 3.4 Infiltration and Soils The most significant factor affecting infiltration is the nature of the soil on the watershed. Accordingly, the U.S. Department of Agriculture Soil Conservation Service (now the Natural Resource Conservation Service) classifies soils according to their infiltration capacity. Soils in the study area are classified as SCS Soil Type A and SCS Soil Type B according to the Natural Resource Conservation Service Web Soil Survey (see Appendix C, Reference Materials). Soils in Group A have a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. Soils in Group B have a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderate well drained or well drained soils that have moderately fine texture to moderately coarse texture. Other important factors in soil infiltration are the antecedent moisture condition (AMC) and land use/soil cover. Following the methodology outlined in the Orange County Hydrology manual, an AMC II (moderate runoff potential) was assumed for events with a 10-year and 25-year return period and AMC III (highest runoff potential) for events with a 100-year return period. 3.5 Watershed Model Development City Plaza drainage study was completed using the Advance Engineering Software (AES) HydroWIN v. 2013 Rational Method Analysis computer program. The computer program uses Orange County methodology to perform the hydrologic analysis of a network of watershed basins. 3.6 Design Hydrology The 10-year, 25-year and 100-year storm events were calculated for the entire watershed for the ultimate condition. Other smaller storm return period analysis may be used during local drainage design stage for catch basin sizing and lateral size determination. 7 D1-7

City Plaza Residential Orange, CA Preliminary Hydrology Report Section 3 - Results 3.1 Existing Hydrology Results The results, based on the Orange County Hydrology Manual guidelines and the computer models developed using AES software, are summarized in the table below for the existing condition. The node points are illustrated on the hydrology map found in Appendix A. DA (Node) 10 YR EVENT 25 YR EVENT 100 YR EVENT Area Q (acres) 100 T c (min) Q 10 (cfs) T c (min) Q 25 (cfs) T c (min) (cfs) A (Node 10) 2.9 6.31 8.22 6.21 10.25 6.08 13.37 A (Node 20) 5.7 9.71 11.84 9.53 14.83 9.21 19.50 Total 11.2 -- 20.06 -- 25.08 -- 32.87 3.2 Proposed Hydrology Results The results, based on the Orange County Hydrology Manual guidelines and the computer models developed using AES software, are summarized in the table below for the proposed condition. The node points are illustrated on the hydrology map found in Appendix B. DA (Node) Area (acres) 10 YR EVENT 25 YR EVENT 100 YR EVENT T c (min) Q 10 (cfs) T c (min) Q 25 (cfs) T c (min) Q 100 (cfs) A (Node 10) 1.9 9.28 4.26 9.27 5.27 9.27 6.80 A (Node 20) 6.7 9.50 13.95 9.40 17.37 9.28 22.58 Total 11.2 -- 18.21 -- 22.64 -- 29.38 3.3 Conclusion The overall site imperviousness was reduced with the proposed development therefore, the volume runoff expected in the entire site was less than existing. 8 D1-8

References City Plaza Residential Orange, CA Preliminary Hydrology Report Manuals Orange County. (1986). Hydrology Manual. Orange County (1996 Addendum). Hydrology Manual. Software Advanced Engineering Systems. HydroWIN7 Version 2013 9 D1-9

Appendix A: EXISTING HYDROLOGY & MAP D1-10

D1-11 14725 Alton Parkway Irvine, CA 92618 Phone: (949) 472-3505 MBAKERINTL.COM

623EX10.RES RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE (Reference: 1986 ORANGE COUNTY HYDROLOGY CRITERION) (c) Copyright 1983-2013 Advanced Engineering Software (aes) Ver. 20.0 Release Date: 06/01/2013 License ID 1264 Analysis prepared by: ************************** DESCRIPTION OF STUDY ************************** * CITY PLAZA RESIDENTIAL * * EXISTING HYDROLOGY - 10 YR STORM EVENT * * 06-21-16 * ************************************************************************** FILE NAME: G:\151623EX.DAT TIME/DATE OF STUDY: 18:18 06/21/2016 USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION: --*TIME-OF-CONCENTRATION MODEL*-- USER SPECIFIED STORM EVENT(YEAR) = 10.00 SPECIFIED MINIMUM PIPE SIZE(INCH) = 18.00 SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE = 0.90 *USER-DEFINED LOGARITHMIC INTERPOLATION USED FOR RAINFALL* SLOPE OF INTENSITY DURATION CURVE(LOG(I;IN/HR) vs. LOG(Tc;MIN)) = 0.6000 USER SPECIFIED 1-HOUR INTENSITY(INCH/HOUR) = 0.8290 *ANTECEDENT MOISTURE CONDITION (AMC) II ASSUMED FOR RATIONAL METHOD* *USER-DEFINED STREET-SECTIONS FOR COUPLED PIPEFLOW AND STREETFLOW MODEL* HALF- CROWN TO STREET-CROSSFALL: CURB GUTTER-GEOMETRIES: MANNING WIDTH CROSSFALL IN- / OUT-/PARK- HEIGHT WIDTH LIP HIKE FACTOR NO. (FT) (FT) SIDE / SIDE/ WAY (FT) (FT) (FT) (FT) (n) === ===== ========= ================= ====== ===== ====== ===== ======= 1 30.0 20.0 0.018/0.018/0.020 0.67 2.00 0.0312 0.167 0.0150 GLOBAL STREET FLOW-DEPTH CONSTRAINTS: 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.* *USER-SPECIFIED MINIMUM TOPOGRAPHIC SLOPE ADJUSTMENT NOT SELECTED FLOW PROCESS FROM NODE 1.00 TO NODE 1.10 IS CODE = 21 >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< >>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< INITIAL SUBAREA FLOW-LENGTH(FEET) = 150.00 ELEVATION DATA: UPSTREAM(FEET) = 127.00 DOWNSTREAM(FEET) = 124.50 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20 SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 5.116 Page 1 623EX10.RES * 10 YEAR RAINFALL INTENSITY(INCH/HR) = 3.631 SUBAREA Tc AND LOSS RATE DATA(AMC II): Tc (MIN.) COMMERCIAL A 0.15 0.40 0.100 32 5.12 PUBLIC PARK A 0.02 0.40 0.850 32 8.13 COMMERCIAL B 0.24 0.30 0.100 56 5.12 PUBLIC PARK B 0.01 0.30 0.850 56 8.13 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.35 SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.154 SUBAREA RUNOFF(CFS) = 1.35 TOTAL AREA(ACRES) = 0.42 PEAK FLOW RATE(CFS) = 1.35 FLOW PROCESS FROM NODE 1.10 TO NODE 1.20 IS CODE = 51 >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<< >>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<< ELEVATION DATA: UPSTREAM(FEET) = 124.50 DOWNSTREAM(FEET) = 122.50 CHANNEL LENGTH THRU SUBAREA(FEET) = 124.50 CHANNEL SLOPE = 0.0161 CHANNEL BASE(FEET) = 50.00 "Z" FACTOR = 0.050 MANNING'S FACTOR = 0.015 MAXIMUM DEPTH(FEET) = 0.50 * 10 YEAR RAINFALL INTENSITY(INCH/HR) = 3.202 SUBAREA LOSS RATE DATA(AMC II): COMMERCIAL A 1.09 0.40 0.100 32 PUBLIC PARK A 0.07 0.40 0.850 32 COMMERCIAL B 1.23 0.30 0.100 56 PUBLIC PARK B 0.09 0.30 0.850 56 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.35 SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.148 TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 4.89 TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 1.74 AVERAGE FLOW DEPTH(FEET) = 0.06 TRAVEL TIME(MIN.) = 1.19 Tc(MIN.) = 6.31 SUBAREA AREA(ACRES) = 2.48 SUBAREA RUNOFF(CFS) = 7.03 EFFECTIVE AREA(ACRES) = 2.90 AREA-AVERAGED Fm(INCH/HR) = 0.05 AREA-AVERAGED Fp(INCH/HR) = 0.35 AREA-AVERAGED Ap = 0.15 TOTAL AREA(ACRES) = 2.9 PEAK FLOW RATE(CFS) = 8.22 END OF SUBAREA CHANNEL FLOW HYDRAULICS: DEPTH(FEET) = 0.07 FLOW VELOCITY(FEET/SEC.) = 2.24 LONGEST FLOWPATH FROM NODE 1.00 TO NODE 1.20 = 274.50 FEET. FLOW PROCESS FROM NODE 1.20 TO NODE 10.00 IS CODE = 31 ELEVATION DATA: UPSTREAM(FEET) = 122.50 DOWNSTREAM(FEET) = 120.50 FLOW LENGTH(FEET) = 248.00 MANNING'S N = 0.013 DEPTH OF FLOW IN 18.0 INCH PIPE IS 13.6 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 5.75 ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 8.22 PIPE TRAVEL TIME(MIN.) = 0.72 Tc(MIN.) = 7.03 LONGEST FLOWPATH FROM NODE 1.00 TO NODE 10.00 = 522.50 FEET. FLOW PROCESS FROM NODE 2.00 TO NODE 2.10 IS CODE = 21 Page 2 D1-12

623EX10.RES >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< >>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< INITIAL SUBAREA FLOW-LENGTH(FEET) = 186.00 ELEVATION DATA: UPSTREAM(FEET) = 127.50 DOWNSTREAM(FEET) = 125.80 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20 SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 6.288 * 10 YEAR RAINFALL INTENSITY(INCH/HR) = 3.209 SUBAREA Tc AND LOSS RATE DATA(AMC II): Tc (MIN.) COMMERCIAL A 0.47 0.40 0.100 32 6.29 PUBLIC PARK A 0.14 0.40 0.850 32 9.99 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.40 SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.272 SUBAREA RUNOFF(CFS) = 1.70 TOTAL AREA(ACRES) = 0.61 PEAK FLOW RATE(CFS) = 1.70 FLOW PROCESS FROM NODE 2.10 TO NODE 2.20 IS CODE = 51 >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<< >>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<< ELEVATION DATA: UPSTREAM(FEET) = 125.80 DOWNSTREAM(FEET) = 121.80 CHANNEL LENGTH THRU SUBAREA(FEET) = 240.00 CHANNEL SLOPE = 0.0167 CHANNEL BASE(FEET) = 50.00 "Z" FACTOR = 0.500 MANNING'S FACTOR = 0.015 MAXIMUM DEPTH(FEET) = 0.50 * 10 YEAR RAINFALL INTENSITY(INCH/HR) = 2.617 SUBAREA LOSS RATE DATA(AMC II): COMMERCIAL A 1.17 0.40 0.100 32 PUBLIC PARK A 0.07 0.40 0.850 32 COMMERCIAL B 0.06 0.30 0.100 56 PUBLIC PARK B 0.01 0.30 0.850 56 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.39 SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.146 TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 3.22 TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 1.57 AVERAGE FLOW DEPTH(FEET) = 0.04 TRAVEL TIME(MIN.) = 2.55 Tc(MIN.) = 8.83 SUBAREA AREA(ACRES) = 1.31 SUBAREA RUNOFF(CFS) = 3.02 EFFECTIVE AREA(ACRES) = 1.92 AREA-AVERAGED Fm(INCH/HR) = 0.07 AREA-AVERAGED Fp(INCH/HR) = 0.40 AREA-AVERAGED Ap = 0.19 TOTAL AREA(ACRES) = 1.9 PEAK FLOW RATE(CFS) = 4.39 END OF SUBAREA CHANNEL FLOW HYDRAULICS: DEPTH(FEET) = 0.05 FLOW VELOCITY(FEET/SEC.) = 1.74 LONGEST FLOWPATH FROM NODE 2.00 TO NODE 2.20 = 426.00 FEET. FLOW PROCESS FROM NODE 2.20 TO NODE 2.20 IS CODE = 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< MAINLINE Tc(MIN.) = 8.83 * 10 YEAR RAINFALL INTENSITY(INCH/HR) = 2.617 SUBAREA LOSS RATE DATA(AMC II): Page 3 623EX10.RES COMMERCIAL A 0.21 0.40 0.100 32 PUBLIC PARK A 0.02 0.40 0.850 32 COMMERCIAL B 0.71 0.30 0.100 56 PUBLIC PARK B 0.06 0.30 0.850 56 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.32 SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.160 SUBAREA AREA(ACRES) = 1.00 SUBAREA RUNOFF(CFS) = 2.31 EFFECTIVE AREA(ACRES) = 2.92 AREA-AVERAGED Fm(INCH/HR) = 0.07 AREA-AVERAGED Fp(INCH/HR) = 0.37 AREA-AVERAGED Ap = 0.18 TOTAL AREA(ACRES) = 2.9 PEAK FLOW RATE(CFS) = 6.70 FLOW PROCESS FROM NODE 2.20 TO NODE 2.30 IS CODE = 31 ELEVATION DATA: UPSTREAM(FEET) = 121.80 DOWNSTREAM(FEET) = 120.90 FLOW LENGTH(FEET) = 195.00 MANNING'S N = 0.013 DEPTH OF FLOW IN 18.0 INCH PIPE IS 14.6 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 4.37 ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 6.70 PIPE TRAVEL TIME(MIN.) = 0.74 Tc(MIN.) = 9.58 LONGEST FLOWPATH FROM NODE 2.00 TO NODE 2.30 = 621.00 FEET. FLOW PROCESS FROM NODE 2.30 TO NODE 2.30 IS CODE = 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< MAINLINE Tc(MIN.) = 9.58 * 10 YEAR RAINFALL INTENSITY(INCH/HR) = 2.493 SUBAREA LOSS RATE DATA(AMC II): COMMERCIAL A 0.95 0.40 0.100 32 PUBLIC PARK A 0.22 0.40 0.850 32 COMMERCIAL B 0.01 0.30 0.100 56 PUBLIC PARK B 0.01 0.30 0.850 56 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.40 SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.245 SUBAREA AREA(ACRES) = 1.19 SUBAREA RUNOFF(CFS) = 2.57 EFFECTIVE AREA(ACRES) = 4.11 AREA-AVERAGED Fm(INCH/HR) = 0.08 AREA-AVERAGED Fp(INCH/HR) = 0.38 AREA-AVERAGED Ap = 0.20 TOTAL AREA(ACRES) = 4.1 PEAK FLOW RATE(CFS) = 8.94 FLOW PROCESS FROM NODE 2.30 TO NODE 20.00 IS CODE = 31 ELEVATION DATA: UPSTREAM(FEET) = 120.90 DOWNSTREAM(FEET) = 120.70 FLOW LENGTH(FEET) = 40.00 MANNING'S N = 0.013 DEPTH OF FLOW IN 21.0 INCH PIPE IS 14.8 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 4.95 ESTIMATED PIPE DIAMETER(INCH) = 21.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 8.94 PIPE TRAVEL TIME(MIN.) = 0.13 Tc(MIN.) = 9.71 LONGEST FLOWPATH FROM NODE 2.00 TO NODE 20.00 = 661.00 FEET. Page 4 D1-13

623EX10.RES FLOW PROCESS FROM NODE 20.00 TO NODE 20.00 IS CODE = 1 >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<< TOTAL NUMBER OF STREAMS = 2 CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE: TIME OF CONCENTRATION(MIN.) = 9.71 RAINFALL INTENSITY(INCH/HR) = 2.47 AREA-AVERAGED Fm(INCH/HR) = 0.08 AREA-AVERAGED Fp(INCH/HR) = 0.38 AREA-AVERAGED Ap = 0.20 EFFECTIVE STREAM AREA(ACRES) = 4.11 TOTAL STREAM AREA(ACRES) = 4.11 PEAK FLOW RATE(CFS) AT CONFLUENCE = 8.94 FLOW PROCESS FROM NODE 2.40 TO NODE 2.50 IS CODE = 21 >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< >>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< INITIAL SUBAREA FLOW-LENGTH(FEET) = 250.00 ELEVATION DATA: UPSTREAM(FEET) = 128.00 DOWNSTREAM(FEET) = 126.00 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20 SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 7.268 * 10 YEAR RAINFALL INTENSITY(INCH/HR) = 2.942 SUBAREA Tc AND LOSS RATE DATA(AMC II): Tc (MIN.) COMMERCIAL A 0.45 0.40 0.100 32 7.27 PUBLIC PARK A 0.28 0.40 0.850 32 11.55 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.40 SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.388 SUBAREA RUNOFF(CFS) = 1.83 TOTAL AREA(ACRES) = 0.73 PEAK FLOW RATE(CFS) = 1.83 FLOW PROCESS FROM NODE 2.50 TO NODE 20.00 IS CODE = 62 >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>(STREET TABLE SECTION # 1 USED)<<<<< UPSTREAM ELEVATION(FEET) = 126.00 DOWNSTREAM ELEVATION(FEET) = 120.70 STREET LENGTH(FEET) = 525.00 CURB HEIGHT(INCHES) = 8.0 STREET HALFWIDTH(FEET) = 30.00 DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 20.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.018 OUTSIDE STREET CROSSFALL(DECIMAL) = 0.018 SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1 STREET PARKWAY CROSSFALL(DECIMAL) = 0.020 Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0200 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 2.66 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW: STREET FLOW DEPTH(FEET) = 0.35 HALFSTREET FLOOD WIDTH(FEET) = 10.51 AVERAGE FLOW VELOCITY(FEET/SEC.) = 2.26 PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 0.79 STREET FLOW TRAVEL TIME(MIN.) = 3.88 Tc(MIN.) = 11.14 Page 5 623EX10.RES * 10 YEAR RAINFALL INTENSITY(INCH/HR) = 2.276 SUBAREA LOSS RATE DATA(AMC II): COMMERCIAL A 0.72 0.40 0.100 32 PUBLIC PARK A 0.12 0.40 0.850 32 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.40 SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.207 SUBAREA AREA(ACRES) = 0.84 SUBAREA RUNOFF(CFS) = 1.66 EFFECTIVE AREA(ACRES) = 1.57 AREA-AVERAGED Fm(INCH/HR) = 0.12 AREA-AVERAGED Fp(INCH/HR) = 0.40 AREA-AVERAGED Ap = 0.29 TOTAL AREA(ACRES) = 1.6 PEAK FLOW RATE(CFS) = 3.05 END OF SUBAREA STREET FLOW HYDRAULICS: DEPTH(FEET) = 0.36 HALFSTREET FLOOD WIDTH(FEET) = 11.21 FLOW VELOCITY(FEET/SEC.) = 2.32 DEPTH*VELOCITY(FT*FT/SEC.) = 0.84 LONGEST FLOWPATH FROM NODE 2.40 TO NODE 20.00 = 775.00 FEET. FLOW PROCESS FROM NODE 20.00 TO NODE 20.00 IS CODE = 1 >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<< >>>>>AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES<<<<< TOTAL NUMBER OF STREAMS = 2 CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 2 ARE: TIME OF CONCENTRATION(MIN.) = 11.14 RAINFALL INTENSITY(INCH/HR) = 2.28 AREA-AVERAGED Fm(INCH/HR) = 0.12 AREA-AVERAGED Fp(INCH/HR) = 0.40 AREA-AVERAGED Ap = 0.29 EFFECTIVE STREAM AREA(ACRES) = 1.57 TOTAL STREAM AREA(ACRES) = 1.57 PEAK FLOW RATE(CFS) AT CONFLUENCE = 3.05 ** CONFLUENCE DATA ** STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 8.94 9.71 2.472 0.38( 0.08) 0.20 4.1 2.00 2 3.05 11.14 2.276 0.40( 0.12) 0.29 1.6 2.40 RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO CONFLUENCE FORMULA USED FOR 2 STREAMS. ** PEAK FLOW RATE TABLE ** STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 11.84 9.71 2.472 0.39( 0.09) 0.22 5.5 2.00 2 11.26 11.14 2.276 0.39( 0.09) 0.22 5.7 2.40 COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS: PEAK FLOW RATE(CFS) = 11.84 Tc(MIN.) = 9.71 EFFECTIVE AREA(ACRES) = 5.48 AREA-AVERAGED Fm(INCH/HR) = 0.09 AREA-AVERAGED Fp(INCH/HR) = 0.39 AREA-AVERAGED Ap = 0.22 TOTAL AREA(ACRES) = 5.7 LONGEST FLOWPATH FROM NODE 2.40 TO NODE 20.00 = 775.00 FEET. END OF STUDY SUMMARY: TOTAL AREA(ACRES) = 5.7 TC(MIN.) = 9.71 EFFECTIVE AREA(ACRES) = 5.48 AREA-AVERAGED Fm(INCH/HR)= 0.09 AREA-AVERAGED Fp(INCH/HR) = 0.39 AREA-AVERAGED Ap = 0.220 PEAK FLOW RATE(CFS) = 11.84 Page 6 D1-14

623EX10.RES ** PEAK FLOW RATE TABLE ** STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 11.84 9.71 2.472 0.39( 0.09) 0.22 5.5 2.00 2 11.26 11.14 2.276 0.39( 0.09) 0.22 5.7 2.40 END OF RATIONAL METHOD ANALYSIS Page 7 D1-15

623EX25.RES RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE (Reference: 1986 ORANGE COUNTY HYDROLOGY CRITERION) (c) Copyright 1983-2013 Advanced Engineering Software (aes) Ver. 20.0 Release Date: 06/01/2013 License ID 1264 Analysis prepared by: ************************** DESCRIPTION OF STUDY ************************** * CITY PLAZA RESIDENTIAL * * EXISTING HYDROLOGY - 25 YR STORM EVENT * * 06-21-16 * ************************************************************************** FILE NAME: G:\151623EX.DAT TIME/DATE OF STUDY: 18:14 06/21/2016 USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION: --*TIME-OF-CONCENTRATION MODEL*-- USER SPECIFIED STORM EVENT(YEAR) = 25.00 SPECIFIED MINIMUM PIPE SIZE(INCH) = 18.00 SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE = 0.90 *USER-DEFINED LOGARITHMIC INTERPOLATION USED FOR RAINFALL* SLOPE OF INTENSITY DURATION CURVE(LOG(I;IN/HR) vs. LOG(Tc;MIN)) = 0.6000 USER SPECIFIED 1-HOUR INTENSITY(INCH/HOUR) = 1.0200 *ANTECEDENT MOISTURE CONDITION (AMC) II ASSUMED FOR RATIONAL METHOD* *USER-DEFINED STREET-SECTIONS FOR COUPLED PIPEFLOW AND STREETFLOW MODEL* HALF- CROWN TO STREET-CROSSFALL: CURB GUTTER-GEOMETRIES: MANNING WIDTH CROSSFALL IN- / OUT-/PARK- HEIGHT WIDTH LIP HIKE FACTOR NO. (FT) (FT) SIDE / SIDE/ WAY (FT) (FT) (FT) (FT) (n) === ===== ========= ================= ====== ===== ====== ===== ======= 1 30.0 20.0 0.018/0.018/0.020 0.67 2.00 0.0313 0.167 0.0150 GLOBAL STREET FLOW-DEPTH CONSTRAINTS: 1. Relative Flow-Depth = 0.00 FEET as (Maximum Allowable Street Flow Depth) - (Top-of-Curb) 2. (Depth)*(Velocity) Constraint = 6.0 (FT*FT/S) *SIZE PIPE WITH A FLOW CAPACITY GREATER THAN OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.* *USER-SPECIFIED MINIMUM TOPOGRAPHIC SLOPE ADJUSTMENT NOT SELECTED FLOW PROCESS FROM NODE 1.00 TO NODE 1.10 IS CODE = 21 >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< >>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< INITIAL SUBAREA FLOW-LENGTH(FEET) = 150.00 ELEVATION DATA: UPSTREAM(FEET) = 127.00 DOWNSTREAM(FEET) = 124.50 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20 SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 5.116 Page 1 623EX25.RES * 25 YEAR RAINFALL INTENSITY(INCH/HR) = 4.468 SUBAREA Tc AND LOSS RATE DATA(AMC II): Tc (MIN.) COMMERCIAL A 0.15 0.40 0.100 32 5.12 PUBLIC PARK A 0.02 0.40 0.850 32 8.13 COMMERCIAL B 0.24 0.30 0.100 56 5.12 PUBLIC PARK B 0.01 0.30 0.850 56 8.13 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.35 SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.154 SUBAREA RUNOFF(CFS) = 1.67 TOTAL AREA(ACRES) = 0.42 PEAK FLOW RATE(CFS) = 1.67 FLOW PROCESS FROM NODE 1.10 TO NODE 1.20 IS CODE = 51 >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<< >>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<< ELEVATION DATA: UPSTREAM(FEET) = 124.50 DOWNSTREAM(FEET) = 122.50 CHANNEL LENGTH THRU SUBAREA(FEET) = 124.50 CHANNEL SLOPE = 0.0161 CHANNEL BASE(FEET) = 50.00 "Z" FACTOR = 0.050 MANNING'S FACTOR = 0.015 MAXIMUM DEPTH(FEET) = 0.50 * 25 YEAR RAINFALL INTENSITY(INCH/HR) = 3.979 SUBAREA LOSS RATE DATA(AMC II): COMMERCIAL A 1.09 0.40 0.100 32 PUBLIC PARK A 0.07 0.40 0.850 32 COMMERCIAL B 1.23 0.30 0.100 56 PUBLIC PARK B 0.09 0.30 0.850 56 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.35 SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.148 TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 6.08 TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 1.90 AVERAGE FLOW DEPTH(FEET) = 0.06 TRAVEL TIME(MIN.) = 1.09 Tc(MIN.) = 6.21 SUBAREA AREA(ACRES) = 2.48 SUBAREA RUNOFF(CFS) = 8.77 EFFECTIVE AREA(ACRES) = 2.90 AREA-AVERAGED Fm(INCH/HR) = 0.05 AREA-AVERAGED Fp(INCH/HR) = 0.35 AREA-AVERAGED Ap = 0.15 TOTAL AREA(ACRES) = 2.9 PEAK FLOW RATE(CFS) = 10.25 END OF SUBAREA CHANNEL FLOW HYDRAULICS: DEPTH(FEET) = 0.09 FLOW VELOCITY(FEET/SEC.) = 2.36 LONGEST FLOWPATH FROM NODE 1.00 TO NODE 1.20 = 274.50 FEET. FLOW PROCESS FROM NODE 1.20 TO NODE 10.00 IS CODE = 31 ELEVATION DATA: UPSTREAM(FEET) = 122.50 DOWNSTREAM(FEET) = 120.50 FLOW LENGTH(FEET) = 248.00 MANNING'S N = 0.013 DEPTH OF FLOW IN 21.0 INCH PIPE IS 13.7 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 6.17 ESTIMATED PIPE DIAMETER(INCH) = 21.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 10.25 PIPE TRAVEL TIME(MIN.) = 0.67 Tc(MIN.) = 6.88 LONGEST FLOWPATH FROM NODE 1.00 TO NODE 10.00 = 522.50 FEET. FLOW PROCESS FROM NODE 2.00 TO NODE 2.10 IS CODE = 21 Page 2 D1-16

623EX25.RES >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< >>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< INITIAL SUBAREA FLOW-LENGTH(FEET) = 186.00 ELEVATION DATA: UPSTREAM(FEET) = 127.50 DOWNSTREAM(FEET) = 125.80 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20 SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 6.288 * 25 YEAR RAINFALL INTENSITY(INCH/HR) = 3.948 SUBAREA Tc AND LOSS RATE DATA(AMC II): Tc (MIN.) COMMERCIAL A 0.47 0.40 0.100 32 6.29 PUBLIC PARK A 0.14 0.40 0.850 32 9.99 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.40 SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.272 SUBAREA RUNOFF(CFS) = 2.11 TOTAL AREA(ACRES) = 0.61 PEAK FLOW RATE(CFS) = 2.11 FLOW PROCESS FROM NODE 2.10 TO NODE 2.20 IS CODE = 51 >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<< >>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<< ELEVATION DATA: UPSTREAM(FEET) = 125.80 DOWNSTREAM(FEET) = 121.80 CHANNEL LENGTH THRU SUBAREA(FEET) = 240.00 CHANNEL SLOPE = 0.0167 CHANNEL BASE(FEET) = 50.00 "Z" FACTOR = 0.500 MANNING'S FACTOR = 0.015 MAXIMUM DEPTH(FEET) = 0.50 * 25 YEAR RAINFALL INTENSITY(INCH/HR) = 3.245 SUBAREA LOSS RATE DATA(AMC II): COMMERCIAL A 1.17 0.40 0.100 32 PUBLIC PARK A 0.07 0.40 0.850 32 COMMERCIAL B 0.06 0.30 0.100 56 PUBLIC PARK B 0.01 0.30 0.850 56 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.39 SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.146 TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 4.00 TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 1.65 AVERAGE FLOW DEPTH(FEET) = 0.05 TRAVEL TIME(MIN.) = 2.43 Tc(MIN.) = 8.72 SUBAREA AREA(ACRES) = 1.31 SUBAREA RUNOFF(CFS) = 3.76 EFFECTIVE AREA(ACRES) = 1.92 AREA-AVERAGED Fm(INCH/HR) = 0.07 AREA-AVERAGED Fp(INCH/HR) = 0.40 AREA-AVERAGED Ap = 0.19 TOTAL AREA(ACRES) = 1.9 PEAK FLOW RATE(CFS) = 5.48 END OF SUBAREA CHANNEL FLOW HYDRAULICS: DEPTH(FEET) = 0.06 FLOW VELOCITY(FEET/SEC.) = 1.88 LONGEST FLOWPATH FROM NODE 2.00 TO NODE 2.20 = 426.00 FEET. FLOW PROCESS FROM NODE 2.20 TO NODE 2.20 IS CODE = 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< MAINLINE Tc(MIN.) = 8.72 * 25 YEAR RAINFALL INTENSITY(INCH/HR) = 3.245 SUBAREA LOSS RATE DATA(AMC II): Page 3 623EX25.RES COMMERCIAL A 0.21 0.40 0.100 32 PUBLIC PARK A 0.02 0.40 0.850 32 COMMERCIAL B 0.71 0.30 0.100 56 PUBLIC PARK B 0.06 0.30 0.850 56 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.32 SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.160 SUBAREA AREA(ACRES) = 1.00 SUBAREA RUNOFF(CFS) = 2.87 EFFECTIVE AREA(ACRES) = 2.92 AREA-AVERAGED Fm(INCH/HR) = 0.07 AREA-AVERAGED Fp(INCH/HR) = 0.37 AREA-AVERAGED Ap = 0.18 TOTAL AREA(ACRES) = 2.9 PEAK FLOW RATE(CFS) = 8.35 FLOW PROCESS FROM NODE 2.20 TO NODE 2.30 IS CODE = 31 ELEVATION DATA: UPSTREAM(FEET) = 121.80 DOWNSTREAM(FEET) = 120.90 FLOW LENGTH(FEET) = 195.00 MANNING'S N = 0.013 DEPTH OF FLOW IN 21.0 INCH PIPE IS 14.4 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 4.74 ESTIMATED PIPE DIAMETER(INCH) = 21.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 8.35 PIPE TRAVEL TIME(MIN.) = 0.69 Tc(MIN.) = 9.41 LONGEST FLOWPATH FROM NODE 2.00 TO NODE 2.30 = 621.00 FEET. FLOW PROCESS FROM NODE 2.30 TO NODE 2.30 IS CODE = 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< MAINLINE Tc(MIN.) = 9.41 * 25 YEAR RAINFALL INTENSITY(INCH/HR) = 3.101 SUBAREA LOSS RATE DATA(AMC II): COMMERCIAL A 0.95 0.40 0.100 32 PUBLIC PARK A 0.22 0.40 0.850 32 COMMERCIAL B 0.01 0.30 0.100 56 PUBLIC PARK B 0.01 0.30 0.850 56 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.40 SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.245 SUBAREA AREA(ACRES) = 1.19 SUBAREA RUNOFF(CFS) = 3.22 EFFECTIVE AREA(ACRES) = 4.11 AREA-AVERAGED Fm(INCH/HR) = 0.08 AREA-AVERAGED Fp(INCH/HR) = 0.38 AREA-AVERAGED Ap = 0.20 TOTAL AREA(ACRES) = 4.1 PEAK FLOW RATE(CFS) = 11.19 FLOW PROCESS FROM NODE 2.30 TO NODE 20.00 IS CODE = 31 ELEVATION DATA: UPSTREAM(FEET) = 120.90 DOWNSTREAM(FEET) = 120.70 FLOW LENGTH(FEET) = 40.00 MANNING'S N = 0.013 DEPTH OF FLOW IN 24.0 INCH PIPE IS 15.3 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 5.28 ESTIMATED PIPE DIAMETER(INCH) = 24.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 11.19 PIPE TRAVEL TIME(MIN.) = 0.13 Tc(MIN.) = 9.53 LONGEST FLOWPATH FROM NODE 2.00 TO NODE 20.00 = 661.00 FEET. Page 4 D1-17

623EX25.RES FLOW PROCESS FROM NODE 20.00 TO NODE 20.00 IS CODE = 1 >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<< TOTAL NUMBER OF STREAMS = 2 CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE: TIME OF CONCENTRATION(MIN.) = 9.53 RAINFALL INTENSITY(INCH/HR) = 3.08 AREA-AVERAGED Fm(INCH/HR) = 0.08 AREA-AVERAGED Fp(INCH/HR) = 0.38 AREA-AVERAGED Ap = 0.20 EFFECTIVE STREAM AREA(ACRES) = 4.11 TOTAL STREAM AREA(ACRES) = 4.11 PEAK FLOW RATE(CFS) AT CONFLUENCE = 11.19 FLOW PROCESS FROM NODE 2.40 TO NODE 2.50 IS CODE = 21 >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< >>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< INITIAL SUBAREA FLOW-LENGTH(FEET) = 250.00 ELEVATION DATA: UPSTREAM(FEET) = 128.00 DOWNSTREAM(FEET) = 126.00 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20 SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 7.268 * 25 YEAR RAINFALL INTENSITY(INCH/HR) = 3.619 SUBAREA Tc AND LOSS RATE DATA(AMC II): Tc (MIN.) COMMERCIAL A 0.45 0.40 0.100 32 7.27 PUBLIC PARK A 0.28 0.40 0.850 32 11.55 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.40 SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.388 SUBAREA RUNOFF(CFS) = 2.28 TOTAL AREA(ACRES) = 0.73 PEAK FLOW RATE(CFS) = 2.28 FLOW PROCESS FROM NODE 2.50 TO NODE 20.00 IS CODE = 62 >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>(STREET TABLE SECTION # 1 USED)<<<<< UPSTREAM ELEVATION(FEET) = 126.00 DOWNSTREAM ELEVATION(FEET) = 120.70 STREET LENGTH(FEET) = 525.00 CURB HEIGHT(INCHES) = 8.0 STREET HALFWIDTH(FEET) = 30.00 DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 20.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.018 OUTSIDE STREET CROSSFALL(DECIMAL) = 0.018 SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1 STREET PARKWAY CROSSFALL(DECIMAL) = 0.020 Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0200 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 3.32 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW: STREET FLOW DEPTH(FEET) = 0.37 HALFSTREET FLOOD WIDTH(FEET) = 11.60 AVERAGE FLOW VELOCITY(FEET/SEC.) = 2.38 PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 0.88 STREET FLOW TRAVEL TIME(MIN.) = 3.68 Tc(MIN.) = 10.95 Page 5 623EX25.RES * 25 YEAR RAINFALL INTENSITY(INCH/HR) = 2.831 SUBAREA LOSS RATE DATA(AMC II): COMMERCIAL A 0.72 0.40 0.100 32 PUBLIC PARK A 0.12 0.40 0.850 32 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.40 SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.207 SUBAREA AREA(ACRES) = 0.84 SUBAREA RUNOFF(CFS) = 2.08 EFFECTIVE AREA(ACRES) = 1.57 AREA-AVERAGED Fm(INCH/HR) = 0.12 AREA-AVERAGED Fp(INCH/HR) = 0.40 AREA-AVERAGED Ap = 0.29 TOTAL AREA(ACRES) = 1.6 PEAK FLOW RATE(CFS) = 3.84 END OF SUBAREA STREET FLOW HYDRAULICS: DEPTH(FEET) = 0.38 HALFSTREET FLOOD WIDTH(FEET) = 12.38 FLOW VELOCITY(FEET/SEC.) = 2.45 DEPTH*VELOCITY(FT*FT/SEC.) = 0.94 LONGEST FLOWPATH FROM NODE 2.40 TO NODE 20.00 = 775.00 FEET. FLOW PROCESS FROM NODE 20.00 TO NODE 20.00 IS CODE = 1 >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<< >>>>>AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES<<<<< TOTAL NUMBER OF STREAMS = 2 CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 2 ARE: TIME OF CONCENTRATION(MIN.) = 10.95 RAINFALL INTENSITY(INCH/HR) = 2.83 AREA-AVERAGED Fm(INCH/HR) = 0.12 AREA-AVERAGED Fp(INCH/HR) = 0.40 AREA-AVERAGED Ap = 0.29 EFFECTIVE STREAM AREA(ACRES) = 1.57 TOTAL STREAM AREA(ACRES) = 1.57 PEAK FLOW RATE(CFS) AT CONFLUENCE = 3.84 ** CONFLUENCE DATA ** STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 11.19 9.53 3.076 0.38( 0.08) 0.20 4.1 2.00 2 3.84 10.95 2.831 0.40( 0.12) 0.29 1.6 2.40 RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO CONFLUENCE FORMULA USED FOR 2 STREAMS. ** PEAK FLOW RATE TABLE ** STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 14.83 9.53 3.076 0.39( 0.09) 0.22 5.5 2.00 2 14.11 10.95 2.831 0.39( 0.09) 0.22 5.7 2.40 COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS: PEAK FLOW RATE(CFS) = 14.83 Tc(MIN.) = 9.53 EFFECTIVE AREA(ACRES) = 5.48 AREA-AVERAGED Fm(INCH/HR) = 0.09 AREA-AVERAGED Fp(INCH/HR) = 0.39 AREA-AVERAGED Ap = 0.22 TOTAL AREA(ACRES) = 5.7 LONGEST FLOWPATH FROM NODE 2.40 TO NODE 20.00 = 775.00 FEET. END OF STUDY SUMMARY: TOTAL AREA(ACRES) = 5.7 TC(MIN.) = 9.53 EFFECTIVE AREA(ACRES) = 5.48 AREA-AVERAGED Fm(INCH/HR)= 0.09 AREA-AVERAGED Fp(INCH/HR) = 0.39 AREA-AVERAGED Ap = 0.220 PEAK FLOW RATE(CFS) = 14.83 Page 6 D1-18

623EX25.RES ** PEAK FLOW RATE TABLE ** STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 14.83 9.53 3.076 0.39( 0.09) 0.22 5.5 2.00 2 14.11 10.95 2.831 0.39( 0.09) 0.22 5.7 2.40 END OF RATIONAL METHOD ANALYSIS Page 7 D1-19

623EX100.RES RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE (Reference: 1986 ORANGE COUNTY HYDROLOGY CRITERION) (c) Copyright 1983-2013 Advanced Engineering Software (aes) Ver. 20.0 Release Date: 06/01/2013 License ID 1264 Analysis prepared by: ************************** DESCRIPTION OF STUDY ************************** * CITY PLAZA RESIDENTIAL * * EXISTING HYDROLOGY - 100 YR STORM EVENT * * 06-21-16 * ************************************************************************** FILE NAME: G:\151623EX.DAT TIME/DATE OF STUDY: 17:48 06/21/2016 USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION: --*TIME-OF-CONCENTRATION MODEL*-- USER SPECIFIED STORM EVENT(YEAR) = 100.00 SPECIFIED MINIMUM PIPE SIZE(INCH) = 18.00 SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE = 0.90 *USER-DEFINED LOGARITHMIC INTERPOLATION USED FOR RAINFALL* SLOPE OF INTENSITY DURATION CURVE(LOG(I;IN/HR) vs. LOG(Tc;MIN)) = 0.6000 USER SPECIFIED 1-HOUR INTENSITY(INCH/HOUR) = 1.3100 *ANTECEDENT MOISTURE CONDITION (AMC) III ASSUMED FOR RATIONAL METHOD* *USER-DEFINED STREET-SECTIONS FOR COUPLED PIPEFLOW AND STREETFLOW MODEL* HALF- CROWN TO STREET-CROSSFALL: CURB GUTTER-GEOMETRIES: MANNING WIDTH CROSSFALL IN- / OUT-/PARK- HEIGHT WIDTH LIP HIKE FACTOR NO. (FT) (FT) SIDE / SIDE/ WAY (FT) (FT) (FT) (FT) (n) === ===== ========= ================= ====== ===== ====== ===== ======= 1 30.0 20.0 0.018/0.018/0.020 0.67 2.00 0.0313 0.167 0.0150 GLOBAL STREET FLOW-DEPTH CONSTRAINTS: 1. Relative Flow-Depth = 0.00 FEET as (Maximum Allowable Street Flow Depth) - (Top-of-Curb) 2. (Depth)*(Velocity) Constraint = 6.0 (FT*FT/S) *SIZE PIPE WITH A FLOW CAPACITY GREATER THAN OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.* *USER-SPECIFIED MINIMUM TOPOGRAPHIC SLOPE ADJUSTMENT NOT SELECTED FLOW PROCESS FROM NODE 1.00 TO NODE 1.10 IS CODE = 21 >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< >>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< INITIAL SUBAREA FLOW-LENGTH(FEET) = 150.00 ELEVATION DATA: UPSTREAM(FEET) = 127.00 DOWNSTREAM(FEET) = 124.50 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20 SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 5.116 Page 1 623EX100.RES * 100 YEAR RAINFALL INTENSITY(INCH/HR) = 5.738 SUBAREA Tc AND LOSS RATE DATA(AMC III): Tc (MIN.) COMMERCIAL A 0.15 0.40 0.100 52 5.12 PUBLIC PARK A 0.02 0.40 0.850 52 8.13 COMMERCIAL B 0.24 0.30 0.100 76 5.12 PUBLIC PARK B 0.01 0.30 0.850 76 8.13 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.35 SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.154 SUBAREA RUNOFF(CFS) = 2.15 TOTAL AREA(ACRES) = 0.42 PEAK FLOW RATE(CFS) = 2.15 FLOW PROCESS FROM NODE 1.10 TO NODE 1.20 IS CODE = 51 >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<< >>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<< ELEVATION DATA: UPSTREAM(FEET) = 124.50 DOWNSTREAM(FEET) = 122.50 CHANNEL LENGTH THRU SUBAREA(FEET) = 124.50 CHANNEL SLOPE = 0.0161 CHANNEL BASE(FEET) = 50.00 "Z" FACTOR = 0.050 MANNING'S FACTOR = 0.015 MAXIMUM DEPTH(FEET) = 0.50 * 100 YEAR RAINFALL INTENSITY(INCH/HR) = 5.174 SUBAREA LOSS RATE DATA(AMC III): COMMERCIAL A 1.09 0.40 0.100 52 PUBLIC PARK A 0.07 0.40 0.850 52 COMMERCIAL B 1.23 0.30 0.100 76 PUBLIC PARK B 0.09 0.30 0.850 76 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.35 SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.148 TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 7.90 TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 2.15 AVERAGE FLOW DEPTH(FEET) = 0.07 TRAVEL TIME(MIN.) = 0.96 Tc(MIN.) = 6.08 SUBAREA AREA(ACRES) = 2.48 SUBAREA RUNOFF(CFS) = 11.43 EFFECTIVE AREA(ACRES) = 2.90 AREA-AVERAGED Fm(INCH/HR) = 0.05 AREA-AVERAGED Fp(INCH/HR) = 0.35 AREA-AVERAGED Ap = 0.15 TOTAL AREA(ACRES) = 2.9 PEAK FLOW RATE(CFS) = 13.37 END OF SUBAREA CHANNEL FLOW HYDRAULICS: DEPTH(FEET) = 0.10 FLOW VELOCITY(FEET/SEC.) = 2.62 LONGEST FLOWPATH FROM NODE 1.00 TO NODE 1.20 = 274.50 FEET. FLOW PROCESS FROM NODE 1.20 TO NODE 10.00 IS CODE = 31 ELEVATION DATA: UPSTREAM(FEET) = 122.50 DOWNSTREAM(FEET) = 120.50 FLOW LENGTH(FEET) = 248.00 MANNING'S N = 0.013 DEPTH OF FLOW IN 21.0 INCH PIPE IS 17.0 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 6.40 ESTIMATED PIPE DIAMETER(INCH) = 21.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 13.37 PIPE TRAVEL TIME(MIN.) = 0.65 Tc(MIN.) = 6.73 LONGEST FLOWPATH FROM NODE 1.00 TO NODE 10.00 = 522.50 FEET. FLOW PROCESS FROM NODE 2.00 TO NODE 2.10 IS CODE = 21 Page 2 D1-20

623EX100.RES >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< >>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< INITIAL SUBAREA FLOW-LENGTH(FEET) = 186.00 ELEVATION DATA: UPSTREAM(FEET) = 127.50 DOWNSTREAM(FEET) = 125.80 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20 SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 6.288 * 100 YEAR RAINFALL INTENSITY(INCH/HR) = 5.071 SUBAREA Tc AND LOSS RATE DATA(AMC III): Tc (MIN.) COMMERCIAL A 0.47 0.40 0.100 52 6.29 PUBLIC PARK A 0.14 0.40 0.850 52 9.99 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.40 SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.272 SUBAREA RUNOFF(CFS) = 2.72 TOTAL AREA(ACRES) = 0.61 PEAK FLOW RATE(CFS) = 2.72 FLOW PROCESS FROM NODE 2.10 TO NODE 2.20 IS CODE = 51 >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<< >>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<< ELEVATION DATA: UPSTREAM(FEET) = 125.80 DOWNSTREAM(FEET) = 121.80 CHANNEL LENGTH THRU SUBAREA(FEET) = 240.00 CHANNEL SLOPE = 0.0167 CHANNEL BASE(FEET) = 50.00 "Z" FACTOR = 0.500 MANNING'S FACTOR = 0.015 MAXIMUM DEPTH(FEET) = 0.50 * 100 YEAR RAINFALL INTENSITY(INCH/HR) = 4.247 SUBAREA LOSS RATE DATA(AMC III): COMMERCIAL A 1.17 0.40 0.100 52 PUBLIC PARK A 0.07 0.40 0.850 52 COMMERCIAL B 0.06 0.30 0.100 76 PUBLIC PARK B 0.01 0.30 0.850 76 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.39 SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.146 TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 5.21 TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 1.85 AVERAGE FLOW DEPTH(FEET) = 0.06 TRAVEL TIME(MIN.) = 2.16 Tc(MIN.) = 8.45 SUBAREA AREA(ACRES) = 1.31 SUBAREA RUNOFF(CFS) = 4.94 EFFECTIVE AREA(ACRES) = 1.92 AREA-AVERAGED Fm(INCH/HR) = 0.07 AREA-AVERAGED Fp(INCH/HR) = 0.40 AREA-AVERAGED Ap = 0.19 TOTAL AREA(ACRES) = 1.9 PEAK FLOW RATE(CFS) = 7.21 END OF SUBAREA CHANNEL FLOW HYDRAULICS: DEPTH(FEET) = 0.07 FLOW VELOCITY(FEET/SEC.) = 2.19 LONGEST FLOWPATH FROM NODE 2.00 TO NODE 2.20 = 426.00 FEET. FLOW PROCESS FROM NODE 2.20 TO NODE 2.20 IS CODE = 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< MAINLINE Tc(MIN.) = 8.45 * 100 YEAR RAINFALL INTENSITY(INCH/HR) = 4.247 SUBAREA LOSS RATE DATA(AMC III): Page 3 623EX100.RES COMMERCIAL A 0.21 0.40 0.100 52 PUBLIC PARK A 0.02 0.40 0.850 52 COMMERCIAL B 0.71 0.30 0.100 76 PUBLIC PARK B 0.06 0.30 0.850 76 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.32 SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.160 SUBAREA AREA(ACRES) = 1.00 SUBAREA RUNOFF(CFS) = 3.78 EFFECTIVE AREA(ACRES) = 2.92 AREA-AVERAGED Fm(INCH/HR) = 0.07 AREA-AVERAGED Fp(INCH/HR) = 0.37 AREA-AVERAGED Ap = 0.18 TOTAL AREA(ACRES) = 2.9 PEAK FLOW RATE(CFS) = 10.99 FLOW PROCESS FROM NODE 2.20 TO NODE 2.30 IS CODE = 31 ELEVATION DATA: UPSTREAM(FEET) = 121.80 DOWNSTREAM(FEET) = 120.90 FLOW LENGTH(FEET) = 195.00 MANNING'S N = 0.013 DEPTH OF FLOW IN 24.0 INCH PIPE IS 15.6 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 5.10 ESTIMATED PIPE DIAMETER(INCH) = 24.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 10.99 PIPE TRAVEL TIME(MIN.) = 0.64 Tc(MIN.) = 9.09 LONGEST FLOWPATH FROM NODE 2.00 TO NODE 2.30 = 621.00 FEET. FLOW PROCESS FROM NODE 2.30 TO NODE 2.30 IS CODE = 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< MAINLINE Tc(MIN.) = 9.09 * 100 YEAR RAINFALL INTENSITY(INCH/HR) = 4.066 SUBAREA LOSS RATE DATA(AMC III): COMMERCIAL A 0.95 0.40 0.100 52 PUBLIC PARK A 0.22 0.40 0.850 52 COMMERCIAL B 0.01 0.30 0.100 76 PUBLIC PARK B 0.01 0.30 0.850 76 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.40 SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.245 SUBAREA AREA(ACRES) = 1.19 SUBAREA RUNOFF(CFS) = 4.25 EFFECTIVE AREA(ACRES) = 4.11 AREA-AVERAGED Fm(INCH/HR) = 0.08 AREA-AVERAGED Fp(INCH/HR) = 0.38 AREA-AVERAGED Ap = 0.20 TOTAL AREA(ACRES) = 4.1 PEAK FLOW RATE(CFS) = 14.76 FLOW PROCESS FROM NODE 2.30 TO NODE 20.00 IS CODE = 31 ELEVATION DATA: UPSTREAM(FEET) = 120.90 DOWNSTREAM(FEET) = 120.70 FLOW LENGTH(FEET) = 40.00 MANNING'S N = 0.013 DEPTH OF FLOW IN 24.0 INCH PIPE IS 19.1 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 5.50 ESTIMATED PIPE DIAMETER(INCH) = 24.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 14.76 PIPE TRAVEL TIME(MIN.) = 0.12 Tc(MIN.) = 9.21 LONGEST FLOWPATH FROM NODE 2.00 TO NODE 20.00 = 661.00 FEET. Page 4 D1-21

623EX100.RES FLOW PROCESS FROM NODE 20.00 TO NODE 20.00 IS CODE = 1 >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<< TOTAL NUMBER OF STREAMS = 2 CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE: TIME OF CONCENTRATION(MIN.) = 9.21 RAINFALL INTENSITY(INCH/HR) = 4.03 AREA-AVERAGED Fm(INCH/HR) = 0.08 AREA-AVERAGED Fp(INCH/HR) = 0.38 AREA-AVERAGED Ap = 0.20 EFFECTIVE STREAM AREA(ACRES) = 4.11 TOTAL STREAM AREA(ACRES) = 4.11 PEAK FLOW RATE(CFS) AT CONFLUENCE = 14.76 FLOW PROCESS FROM NODE 2.40 TO NODE 2.50 IS CODE = 21 >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< >>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< INITIAL SUBAREA FLOW-LENGTH(FEET) = 250.00 ELEVATION DATA: UPSTREAM(FEET) = 128.00 DOWNSTREAM(FEET) = 126.00 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20 SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 7.268 * 100 YEAR RAINFALL INTENSITY(INCH/HR) = 4.648 SUBAREA Tc AND LOSS RATE DATA(AMC III): Tc (MIN.) COMMERCIAL A 0.45 0.40 0.100 52 7.27 PUBLIC PARK A 0.28 0.40 0.850 52 11.55 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.40 SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.388 SUBAREA RUNOFF(CFS) = 2.95 TOTAL AREA(ACRES) = 0.73 PEAK FLOW RATE(CFS) = 2.95 FLOW PROCESS FROM NODE 2.50 TO NODE 20.00 IS CODE = 62 >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>(STREET TABLE SECTION # 1 USED)<<<<< UPSTREAM ELEVATION(FEET) = 126.00 DOWNSTREAM ELEVATION(FEET) = 120.70 STREET LENGTH(FEET) = 525.00 CURB HEIGHT(INCHES) = 8.0 STREET HALFWIDTH(FEET) = 30.00 DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 20.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.018 OUTSIDE STREET CROSSFALL(DECIMAL) = 0.018 SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1 STREET PARKWAY CROSSFALL(DECIMAL) = 0.020 Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0200 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 4.32 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW: STREET FLOW DEPTH(FEET) = 0.40 HALFSTREET FLOOD WIDTH(FEET) = 13.09 AVERAGE FLOW VELOCITY(FEET/SEC.) = 2.50 PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 0.99 STREET FLOW TRAVEL TIME(MIN.) = 3.49 Tc(MIN.) = 10.76 Page 5 623EX100.RES * 100 YEAR RAINFALL INTENSITY(INCH/HR) = 3.673 SUBAREA LOSS RATE DATA(AMC III): COMMERCIAL A 0.72 0.40 0.100 52 PUBLIC PARK A 0.12 0.40 0.850 52 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.40 SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.207 SUBAREA AREA(ACRES) = 0.84 SUBAREA RUNOFF(CFS) = 2.71 EFFECTIVE AREA(ACRES) = 1.57 AREA-AVERAGED Fm(INCH/HR) = 0.12 AREA-AVERAGED Fp(INCH/HR) = 0.40 AREA-AVERAGED Ap = 0.29 TOTAL AREA(ACRES) = 1.6 PEAK FLOW RATE(CFS) = 5.03 END OF SUBAREA STREET FLOW HYDRAULICS: DEPTH(FEET) = 0.41 HALFSTREET FLOOD WIDTH(FEET) = 13.95 FLOW VELOCITY(FEET/SEC.) = 2.60 DEPTH*VELOCITY(FT*FT/SEC.) = 1.07 LONGEST FLOWPATH FROM NODE 2.40 TO NODE 20.00 = 775.00 FEET. FLOW PROCESS FROM NODE 20.00 TO NODE 20.00 IS CODE = 1 >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<< >>>>>AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES<<<<< TOTAL NUMBER OF STREAMS = 2 CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 2 ARE: TIME OF CONCENTRATION(MIN.) = 10.76 RAINFALL INTENSITY(INCH/HR) = 3.67 AREA-AVERAGED Fm(INCH/HR) = 0.12 AREA-AVERAGED Fp(INCH/HR) = 0.40 AREA-AVERAGED Ap = 0.29 EFFECTIVE STREAM AREA(ACRES) = 1.57 TOTAL STREAM AREA(ACRES) = 1.57 PEAK FLOW RATE(CFS) AT CONFLUENCE = 5.03 ** CONFLUENCE DATA ** STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 14.76 9.21 4.034 0.38( 0.08) 0.20 4.1 2.00 2 5.03 10.76 3.673 0.40( 0.12) 0.29 1.6 2.40 RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO CONFLUENCE FORMULA USED FOR 2 STREAMS. ** PEAK FLOW RATE TABLE ** STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 19.50 9.21 4.034 0.39( 0.09) 0.22 5.5 2.00 2 18.44 10.76 3.673 0.39( 0.09) 0.22 5.7 2.40 COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS: PEAK FLOW RATE(CFS) = 19.50 Tc(MIN.) = 9.21 EFFECTIVE AREA(ACRES) = 5.45 AREA-AVERAGED Fm(INCH/HR) = 0.09 AREA-AVERAGED Fp(INCH/HR) = 0.39 AREA-AVERAGED Ap = 0.22 TOTAL AREA(ACRES) = 5.7 LONGEST FLOWPATH FROM NODE 2.40 TO NODE 20.00 = 775.00 FEET. END OF STUDY SUMMARY: TOTAL AREA(ACRES) = 5.7 TC(MIN.) = 9.21 EFFECTIVE AREA(ACRES) = 5.45 AREA-AVERAGED Fm(INCH/HR)= 0.09 AREA-AVERAGED Fp(INCH/HR) = 0.39 AREA-AVERAGED Ap = 0.220 PEAK FLOW RATE(CFS) = 19.50 Page 6 D1-22

623EX100.RES ** PEAK FLOW RATE TABLE ** STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 19.50 9.21 4.034 0.39( 0.09) 0.22 5.5 2.00 2 18.44 10.76 3.673 0.39( 0.09) 0.22 5.7 2.40 END OF RATIONAL METHOD ANALYSIS Page 7 D1-23

Appendix B: PROPOSED HYDROLOGY & MAP D1-24

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RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE (Reference: 1986 ORANGE COUNTY HYDROLOGY CRITERION) (c) Copyright 1983-2011 Advanced Engineering Software (aes) Ver. 18.0 Release Date: 07/01/2011 License ID 1264 Analysis prepared by: ************************** DESCRIPTION OF STUDY ************************** * CITY PLAZA RESIDENTIAL * * PROPOSED HYDROLOGY - 10YR STORM EVENT * * 07-18-16 * ************************************************************************** FILE NAME: 151623PR.DAT TIME/DATE OF STUDY: 20:20 07/18/2016 USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION: --*TIME-OF-CONCENTRATION MODEL*-- USER SPECIFIED STORM EVENT(YEAR) = 10.00 SPECIFIED MINIMUM PIPE SIZE(INCH) = 18.00 SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE = 0.90 *USER-DEFINED LOGARITHMIC INTERPOLATION USED FOR RAINFALL* SLOPE OF INTENSITY DURATION CURVE(LOG(I;IN/HR) vs. LOG(Tc;MIN)) = 0.6000 USER SPECIFIED 1-HOUR INTENSITY(INCH/HOUR) = 0.8290 *ANTECEDENT MOISTURE CONDITION (AMC) I ASSUMED FOR RATIONAL METHOD* *USER-DEFINED STREET-SECTIONS FOR COUPLED PIPEFLOW AND STREETFLOW MODEL* HALF- CROWN TO STREET-CROSSFALL: CURB GUTTER-GEOMETRIES: MANNING WIDTH CROSSFALL IN- / OUT-/PARK- HEIGHT WIDTH LIP HIKE FACTOR NO. (FT) (FT) SIDE / SIDE/ WAY (FT) (FT) (FT) (FT) (n) === ===== ========= ================= ====== ===== ====== ===== ======= 1 30.0 20.0 0.018/0.018/0.020 0.67 2.00 0.0312 0.167 0.0150 GLOBAL STREET FLOW-DEPTH CONSTRAINTS: 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.* *USER-SPECIFIED MINIMUM TOPOGRAPHIC SLOPE ADJUSTMENT NOT SELECTED FLOW PROCESS FROM NODE 1.00 TO NODE 1.10 IS CODE = 21 >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< >>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< Date: 07/18/2016 File name: 623PR10.RES Page 1 D1-26 INITIAL SUBAREA FLOW-LENGTH(FEET) = 300.00 ELEVATION DATA: UPSTREAM(FEET) = 125.00 DOWNSTREAM(FEET) = 123.50 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20 SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 9.154 * 10 YEAR RAINFALL INTENSITY(INCH/HR) = 2.561 SUBAREA Tc AND LOSS RATE DATA(AMC I ): Tc (MIN.) APARTMENTS A 0.01 0.40 0.200 17 9.15 APARTMENTS B 0.35 0.30 0.200 36 9.15 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.30 SUBAREA RUNOFF(CFS) = 0.81 TOTAL AREA(ACRES) = 0.36 PEAK FLOW RATE(CFS) = 0.81 FLOW PROCESS FROM NODE 1.10 TO NODE 1.10 IS CODE = 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< MAINLINE Tc(MIN.) = 9.15 * 10 YEAR RAINFALL INTENSITY(INCH/HR) = 2.561 SUBAREA LOSS RATE DATA(AMC I ): APARTMENTS A 0.99 0.40 0.200 17 APARTMENTS B 0.55 0.30 0.200 36 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.36 SUBAREA AREA(ACRES) = 1.54 SUBAREA RUNOFF(CFS) = 3.45 EFFECTIVE AREA(ACRES) = 1.90 AREA-AVERAGED Fm(INCH/HR) = 0.07 AREA-AVERAGED Fp(INCH/HR) = 0.35 AREA-AVERAGED Ap = 0.20 TOTAL AREA(ACRES) = 1.9 PEAK FLOW RATE(CFS) = 4.26 FLOW PROCESS FROM NODE 1.10 TO NODE 10.00 IS CODE = 31 ELEVATION DATA: UPSTREAM(FEET) = 123.50 DOWNSTREAM(FEET) = 120.50 FLOW LENGTH(FEET) = 70.00 MANNING'S N = 0.013 ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 18.000 DEPTH OF FLOW IN 18.0 INCH PIPE IS 5.6 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 9.19 ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 4.26 PIPE TRAVEL TIME(MIN.) = 0.13 Tc(MIN.) = 9.28 LONGEST FLOWPATH FROM NODE 1.00 TO NODE 10.00 = 370.00 FEET. FLOW PROCESS FROM NODE 2.00 TO NODE 2.10 IS CODE = 21 >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< >>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< INITIAL SUBAREA FLOW-LENGTH(FEET) = 270.00 Date: 07/18/2016 File name: 623PR10.RES Page 2

ELEVATION DATA: UPSTREAM(FEET) = 125.00 DOWNSTREAM(FEET) = 124.00 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20 SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 9.319 * 10 YEAR RAINFALL INTENSITY(INCH/HR) = 2.534 SUBAREA Tc AND LOSS RATE DATA(AMC I ): Tc (MIN.) APARTMENTS A 0.27 0.40 0.200 17 9.32 APARTMENTS B 0.39 0.30 0.200 36 9.32 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.34 SUBAREA RUNOFF(CFS) = 1.46 TOTAL AREA(ACRES) = 0.66 PEAK FLOW RATE(CFS) = 1.46 FLOW PROCESS FROM NODE 2.10 TO NODE 2.20 IS CODE = 31 ELEVATION DATA: UPSTREAM(FEET) = 124.00 DOWNSTREAM(FEET) = 118.90 FLOW LENGTH(FEET) = 369.00 MANNING'S N = 0.013 ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 18.000 DEPTH OF FLOW IN 18.0 INCH PIPE IS 4.3 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 4.52 ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 1.46 PIPE TRAVEL TIME(MIN.) = 1.36 Tc(MIN.) = 10.68 LONGEST FLOWPATH FROM NODE 2.00 TO NODE 2.20 = 639.00 FEET. FLOW PROCESS FROM NODE 2.20 TO NODE 2.20 IS CODE = 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< MAINLINE Tc(MIN.) = 10.68 * 10 YEAR RAINFALL INTENSITY(INCH/HR) = 2.335 SUBAREA LOSS RATE DATA(AMC I ): APARTMENTS A 0.67 0.40 0.200 17 APARTMENTS B 1.03 0.30 0.200 36 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.34 SUBAREA AREA(ACRES) = 1.70 SUBAREA RUNOFF(CFS) = 3.47 EFFECTIVE AREA(ACRES) = 2.36 AREA-AVERAGED Fm(INCH/HR) = 0.07 AREA-AVERAGED Fp(INCH/HR) = 0.34 AREA-AVERAGED Ap = 0.20 TOTAL AREA(ACRES) = 2.4 PEAK FLOW RATE(CFS) = 4.82 FLOW PROCESS FROM NODE 2.20 TO NODE 20.00 IS CODE = 31 ELEVATION DATA: UPSTREAM(FEET) = 118.90 DOWNSTREAM(FEET) = 117.18 FLOW LENGTH(FEET) = 275.00 MANNING'S N = 0.013 Date: 07/18/2016 File name: 623PR10.RES Page 3 D1-27 ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 18.000 DEPTH OF FLOW IN 18.0 INCH PIPE IS 10.2 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 4.68 ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 4.82 PIPE TRAVEL TIME(MIN.) = 0.98 Tc(MIN.) = 11.66 LONGEST FLOWPATH FROM NODE 2.00 TO NODE 20.00 = 914.00 FEET. FLOW PROCESS FROM NODE 20.00 TO NODE 20.00 IS CODE = 1 >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<< TOTAL NUMBER OF STREAMS = 2 CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE: TIME OF CONCENTRATION(MIN.) = 11.66 RAINFALL INTENSITY(INCH/HR) = 2.22 AREA-AVERAGED Fm(INCH/HR) = 0.07 AREA-AVERAGED Fp(INCH/HR) = 0.34 AREA-AVERAGED Ap = 0.20 EFFECTIVE STREAM AREA(ACRES) = 2.36 TOTAL STREAM AREA(ACRES) = 2.36 PEAK FLOW RATE(CFS) AT CONFLUENCE = 4.82 FLOW PROCESS FROM NODE 2.30 TO NODE 2.40 IS CODE = 21 >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< >>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< INITIAL SUBAREA FLOW-LENGTH(FEET) = 300.00 ELEVATION DATA: UPSTREAM(FEET) = 128.00 DOWNSTREAM(FEET) = 124.00 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20 SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 7.523 * 10 YEAR RAINFALL INTENSITY(INCH/HR) = 2.881 SUBAREA Tc AND LOSS RATE DATA(AMC I ): Tc (MIN.) APARTMENTS A 0.87 0.40 0.200 17 7.52 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.40 SUBAREA RUNOFF(CFS) = 2.19 TOTAL AREA(ACRES) = 0.87 PEAK FLOW RATE(CFS) = 2.19 FLOW PROCESS FROM NODE 2.40 TO NODE 2.50 IS CODE = 62 >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>(STREET TABLE SECTION # 1 USED)<<<<< UPSTREAM ELEVATION(FEET) = 124.00 DOWNSTREAM ELEVATION(FEET) = 122.90 STREET LENGTH(FEET) = 152.00 CURB HEIGHT(INCHES) = 8.0 STREET HALFWIDTH(FEET) = 30.00 DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 20.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.018 OUTSIDE STREET CROSSFALL(DECIMAL) = 0.018 Date: 07/18/2016 File name: 623PR10.RES Page 4

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) = 3.73 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW: STREET FLOW DEPTH(FEET) = 0.40 HALFSTREET FLOOD WIDTH(FEET) = 13.16 AVERAGE FLOW VELOCITY(FEET/SEC.) = 2.14 PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 0.85 STREET FLOW TRAVEL TIME(MIN.) = 1.18 Tc(MIN.) = 8.71 * 10 YEAR RAINFALL INTENSITY(INCH/HR) = 2.639 SUBAREA LOSS RATE DATA(AMC I ): APARTMENTS A 1.33 0.40 0.200 17 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.40 SUBAREA AREA(ACRES) = 1.33 SUBAREA RUNOFF(CFS) = 3.06 EFFECTIVE AREA(ACRES) = 2.20 AREA-AVERAGED Fm(INCH/HR) = 0.08 AREA-AVERAGED Fp(INCH/HR) = 0.40 AREA-AVERAGED Ap = 0.20 TOTAL AREA(ACRES) = 2.2 PEAK FLOW RATE(CFS) = 5.07 END OF SUBAREA STREET FLOW HYDRAULICS: DEPTH(FEET) = 0.43 HALFSTREET FLOOD WIDTH(FEET) = 15.04 FLOW VELOCITY(FEET/SEC.) = 2.29 DEPTH*VELOCITY(FT*FT/SEC.) = 0.99 LONGEST FLOWPATH FROM NODE 2.30 TO NODE 2.50 = 452.00 FEET. FLOW PROCESS FROM NODE 2.50 TO NODE 2.60 IS CODE = 31 ELEVATION DATA: UPSTREAM(FEET) = 122.90 DOWNSTREAM(FEET) = 120.00 FLOW LENGTH(FEET) = 95.00 MANNING'S N = 0.013 ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 18.000 DEPTH OF FLOW IN 18.0 INCH PIPE IS 6.7 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 8.54 ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 5.07 PIPE TRAVEL TIME(MIN.) = 0.19 Tc(MIN.) = 8.89 LONGEST FLOWPATH FROM NODE 2.30 TO NODE 2.60 = 547.00 FEET. FLOW PROCESS FROM NODE 2.60 TO NODE 2.60 IS CODE = 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< MAINLINE Tc(MIN.) = 8.89 * 10 YEAR RAINFALL INTENSITY(INCH/HR) = 2.606 SUBAREA LOSS RATE DATA(AMC I ): APARTMENTS A 1.18 0.40 0.200 17 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.40 Date: 07/18/2016 File name: 623PR10.RES Page 5 D1-28 SUBAREA AREA(ACRES) = 1.18 SUBAREA RUNOFF(CFS) = 2.68 EFFECTIVE AREA(ACRES) = 3.38 AREA-AVERAGED Fm(INCH/HR) = 0.08 AREA-AVERAGED Fp(INCH/HR) = 0.40 AREA-AVERAGED Ap = 0.20 TOTAL AREA(ACRES) = 3.4 PEAK FLOW RATE(CFS) = 7.69 FLOW PROCESS FROM NODE 2.60 TO NODE 20.00 IS CODE = 31 ELEVATION DATA: UPSTREAM(FEET) = 120.00 DOWNSTREAM(FEET) = 117.18 FLOW LENGTH(FEET) = 240.00 MANNING'S N = 0.013 DEPTH OF FLOW IN 18.0 INCH PIPE IS 11.2 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 6.64 ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 7.69 PIPE TRAVEL TIME(MIN.) = 0.60 Tc(MIN.) = 9.50 LONGEST FLOWPATH FROM NODE 2.30 TO NODE 20.00 = 787.00 FEET. FLOW PROCESS FROM NODE 20.00 TO NODE 20.00 IS CODE = 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< MAINLINE Tc(MIN.) = 9.50 * 10 YEAR RAINFALL INTENSITY(INCH/HR) = 2.506 SUBAREA LOSS RATE DATA(AMC I ): APARTMENTS A 0.75 0.40 0.200 17 APARTMENTS B 0.22 0.30 0.200 36 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.38 SUBAREA AREA(ACRES) = 0.97 SUBAREA RUNOFF(CFS) = 2.12 EFFECTIVE AREA(ACRES) = 4.35 AREA-AVERAGED Fm(INCH/HR) = 0.08 AREA-AVERAGED Fp(INCH/HR) = 0.39 AREA-AVERAGED Ap = 0.20 TOTAL AREA(ACRES) = 4.4 PEAK FLOW RATE(CFS) = 9.50 FLOW PROCESS FROM NODE 20.00 TO NODE 20.00 IS CODE = 1 >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<< >>>>>AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES<<<<< TOTAL NUMBER OF STREAMS = 2 CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 2 ARE: TIME OF CONCENTRATION(MIN.) = 9.50 RAINFALL INTENSITY(INCH/HR) = 2.51 AREA-AVERAGED Fm(INCH/HR) = 0.08 AREA-AVERAGED Fp(INCH/HR) = 0.39 AREA-AVERAGED Ap = 0.20 EFFECTIVE STREAM AREA(ACRES) = 4.35 TOTAL STREAM AREA(ACRES) = 4.35 PEAK FLOW RATE(CFS) AT CONFLUENCE = 9.50 ** CONFLUENCE DATA ** Date: 07/18/2016 File name: 623PR10.RES Page 6

STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 4.82 11.66 2.215 0.34( 0.07) 0.20 2.4 2.00 2 9.50 9.50 2.506 0.39( 0.08) 0.20 4.4 2.30 RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO CONFLUENCE FORMULA USED FOR 2 STREAMS. ** PEAK FLOW RATE TABLE ** STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 13.95 9.50 2.506 0.38( 0.08) 0.20 6.3 2.30 2 13.18 11.66 2.215 0.38( 0.08) 0.20 6.7 2.00 COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS: PEAK FLOW RATE(CFS) = 13.95 Tc(MIN.) = 9.50 EFFECTIVE AREA(ACRES) = 6.27 AREA-AVERAGED Fm(INCH/HR) = 0.08 AREA-AVERAGED Fp(INCH/HR) = 0.38 AREA-AVERAGED Ap = 0.20 TOTAL AREA(ACRES) = 6.7 LONGEST FLOWPATH FROM NODE 2.00 TO NODE 20.00 = 914.00 FEET. END OF STUDY SUMMARY: TOTAL AREA(ACRES) = 6.7 TC(MIN.) = 9.50 EFFECTIVE AREA(ACRES) = 6.27 AREA-AVERAGED Fm(INCH/HR)= 0.08 AREA-AVERAGED Fp(INCH/HR) = 0.38 AREA-AVERAGED Ap = 0.200 PEAK FLOW RATE(CFS) = 13.95 ** PEAK FLOW RATE TABLE ** STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 13.95 9.50 2.506 0.38( 0.08) 0.20 6.3 2.30 2 13.18 11.66 2.215 0.38( 0.08) 0.20 6.7 2.00 END OF RATIONAL METHOD ANALYSIS Date: 07/18/2016 File name: 623PR10.RES Page 7 D1-29 Date: 07/18/2016 File name: 623PR10.RES Page 8

RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE (Reference: 1986 ORANGE COUNTY HYDROLOGY CRITERION) (c) Copyright 1983-2011 Advanced Engineering Software (aes) Ver. 18.0 Release Date: 07/01/2011 License ID 1264 Analysis prepared by: ************************** DESCRIPTION OF STUDY ************************** * CITY PLAZA RESIDENTIAL * * PROPOSED HYDROLOGY - 25YR STORM EVENT * * 07-18-16 * ************************************************************************** FILE NAME: 151623PR.DAT TIME/DATE OF STUDY: 20:19 07/18/2016 USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION: --*TIME-OF-CONCENTRATION MODEL*-- USER SPECIFIED STORM EVENT(YEAR) = 25.00 SPECIFIED MINIMUM PIPE SIZE(INCH) = 18.00 SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE = 0.90 *USER-DEFINED LOGARITHMIC INTERPOLATION USED FOR RAINFALL* SLOPE OF INTENSITY DURATION CURVE(LOG(I;IN/HR) vs. LOG(Tc;MIN)) = 0.6000 USER SPECIFIED 1-HOUR INTENSITY(INCH/HOUR) = 1.0200 *ANTECEDENT MOISTURE CONDITION (AMC) II ASSUMED FOR RATIONAL METHOD* *USER-DEFINED STREET-SECTIONS FOR COUPLED PIPEFLOW AND STREETFLOW MODEL* HALF- CROWN TO STREET-CROSSFALL: CURB GUTTER-GEOMETRIES: MANNING WIDTH CROSSFALL IN- / OUT-/PARK- HEIGHT WIDTH LIP HIKE FACTOR NO. (FT) (FT) SIDE / SIDE/ WAY (FT) (FT) (FT) (FT) (n) === ===== ========= ================= ====== ===== ====== ===== ======= 1 30.0 20.0 0.018/0.018/0.020 0.67 2.00 0.0312 0.167 0.0150 GLOBAL STREET FLOW-DEPTH CONSTRAINTS: 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.* *USER-SPECIFIED MINIMUM TOPOGRAPHIC SLOPE ADJUSTMENT NOT SELECTED FLOW PROCESS FROM NODE 1.00 TO NODE 1.10 IS CODE = 21 >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< >>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< Date: 07/18/2016 File name: 623PR25.RES Page 1 D1-30 INITIAL SUBAREA FLOW-LENGTH(FEET) = 300.00 ELEVATION DATA: UPSTREAM(FEET) = 125.00 DOWNSTREAM(FEET) = 123.50 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20 SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 9.154 * 25 YEAR RAINFALL INTENSITY(INCH/HR) = 3.152 SUBAREA Tc AND LOSS RATE DATA(AMC II): Tc (MIN.) APARTMENTS A 0.01 0.40 0.200 32 9.15 APARTMENTS B 0.35 0.30 0.200 56 9.15 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.30 SUBAREA RUNOFF(CFS) = 1.00 TOTAL AREA(ACRES) = 0.36 PEAK FLOW RATE(CFS) = 1.00 FLOW PROCESS FROM NODE 1.10 TO NODE 1.10 IS CODE = 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< MAINLINE Tc(MIN.) = 9.15 * 25 YEAR RAINFALL INTENSITY(INCH/HR) = 3.152 SUBAREA LOSS RATE DATA(AMC II): APARTMENTS A 0.99 0.40 0.200 32 APARTMENTS B 0.55 0.30 0.200 56 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.36 SUBAREA AREA(ACRES) = 1.54 SUBAREA RUNOFF(CFS) = 4.27 EFFECTIVE AREA(ACRES) = 1.90 AREA-AVERAGED Fm(INCH/HR) = 0.07 AREA-AVERAGED Fp(INCH/HR) = 0.35 AREA-AVERAGED Ap = 0.20 TOTAL AREA(ACRES) = 1.9 PEAK FLOW RATE(CFS) = 5.27 FLOW PROCESS FROM NODE 1.10 TO NODE 10.00 IS CODE = 31 ELEVATION DATA: UPSTREAM(FEET) = 123.50 DOWNSTREAM(FEET) = 120.50 FLOW LENGTH(FEET) = 70.00 MANNING'S N = 0.013 ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 18.000 DEPTH OF FLOW IN 18.0 INCH PIPE IS 6.2 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 9.76 ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 5.27 PIPE TRAVEL TIME(MIN.) = 0.12 Tc(MIN.) = 9.27 LONGEST FLOWPATH FROM NODE 1.00 TO NODE 10.00 = 370.00 FEET. FLOW PROCESS FROM NODE 2.00 TO NODE 2.10 IS CODE = 21 >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< >>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< INITIAL SUBAREA FLOW-LENGTH(FEET) = 270.00 Date: 07/18/2016 File name: 623PR25.RES Page 2

ELEVATION DATA: UPSTREAM(FEET) = 125.00 DOWNSTREAM(FEET) = 124.00 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20 SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 9.319 * 25 YEAR RAINFALL INTENSITY(INCH/HR) = 3.118 SUBAREA Tc AND LOSS RATE DATA(AMC II): Tc (MIN.) APARTMENTS A 0.27 0.40 0.200 32 9.32 APARTMENTS B 0.39 0.30 0.200 56 9.32 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.34 SUBAREA RUNOFF(CFS) = 1.81 TOTAL AREA(ACRES) = 0.66 PEAK FLOW RATE(CFS) = 1.81 FLOW PROCESS FROM NODE 2.10 TO NODE 2.20 IS CODE = 31 ELEVATION DATA: UPSTREAM(FEET) = 124.00 DOWNSTREAM(FEET) = 118.90 FLOW LENGTH(FEET) = 369.00 MANNING'S N = 0.013 ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 18.000 DEPTH OF FLOW IN 18.0 INCH PIPE IS 4.8 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 4.81 ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 1.81 PIPE TRAVEL TIME(MIN.) = 1.28 Tc(MIN.) = 10.60 LONGEST FLOWPATH FROM NODE 2.00 TO NODE 2.20 = 639.00 FEET. FLOW PROCESS FROM NODE 2.20 TO NODE 2.20 IS CODE = 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< MAINLINE Tc(MIN.) = 10.60 * 25 YEAR RAINFALL INTENSITY(INCH/HR) = 2.886 SUBAREA LOSS RATE DATA(AMC II): APARTMENTS A 0.67 0.40 0.200 32 APARTMENTS B 1.03 0.30 0.200 56 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.34 SUBAREA AREA(ACRES) = 1.70 SUBAREA RUNOFF(CFS) = 4.31 EFFECTIVE AREA(ACRES) = 2.36 AREA-AVERAGED Fm(INCH/HR) = 0.07 AREA-AVERAGED Fp(INCH/HR) = 0.34 AREA-AVERAGED Ap = 0.20 TOTAL AREA(ACRES) = 2.4 PEAK FLOW RATE(CFS) = 5.99 FLOW PROCESS FROM NODE 2.20 TO NODE 20.00 IS CODE = 31 ELEVATION DATA: UPSTREAM(FEET) = 118.90 DOWNSTREAM(FEET) = 117.18 FLOW LENGTH(FEET) = 275.00 MANNING'S N = 0.013 Date: 07/18/2016 File name: 623PR25.RES Page 3 D1-31 DEPTH OF FLOW IN 18.0 INCH PIPE IS 11.7 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 4.91 ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 5.99 PIPE TRAVEL TIME(MIN.) = 0.93 Tc(MIN.) = 11.53 LONGEST FLOWPATH FROM NODE 2.00 TO NODE 20.00 = 914.00 FEET. FLOW PROCESS FROM NODE 20.00 TO NODE 20.00 IS CODE = 1 >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<< TOTAL NUMBER OF STREAMS = 2 CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE: TIME OF CONCENTRATION(MIN.) = 11.53 RAINFALL INTENSITY(INCH/HR) = 2.74 AREA-AVERAGED Fm(INCH/HR) = 0.07 AREA-AVERAGED Fp(INCH/HR) = 0.34 AREA-AVERAGED Ap = 0.20 EFFECTIVE STREAM AREA(ACRES) = 2.36 TOTAL STREAM AREA(ACRES) = 2.36 PEAK FLOW RATE(CFS) AT CONFLUENCE = 5.99 FLOW PROCESS FROM NODE 2.30 TO NODE 2.40 IS CODE = 21 >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< >>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< INITIAL SUBAREA FLOW-LENGTH(FEET) = 300.00 ELEVATION DATA: UPSTREAM(FEET) = 128.00 DOWNSTREAM(FEET) = 124.00 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20 SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 7.523 * 25 YEAR RAINFALL INTENSITY(INCH/HR) = 3.545 SUBAREA Tc AND LOSS RATE DATA(AMC II): Tc (MIN.) APARTMENTS A 0.87 0.40 0.200 32 7.52 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.40 SUBAREA RUNOFF(CFS) = 2.71 TOTAL AREA(ACRES) = 0.87 PEAK FLOW RATE(CFS) = 2.71 FLOW PROCESS FROM NODE 2.40 TO NODE 2.50 IS CODE = 62 >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>(STREET TABLE SECTION # 1 USED)<<<<< UPSTREAM ELEVATION(FEET) = 124.00 DOWNSTREAM ELEVATION(FEET) = 122.90 STREET LENGTH(FEET) = 152.00 CURB HEIGHT(INCHES) = 8.0 STREET HALFWIDTH(FEET) = 30.00 DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 20.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.018 OUTSIDE STREET CROSSFALL(DECIMAL) = 0.018 Date: 07/18/2016 File name: 623PR25.RES Page 4

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) = 4.62 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW: STREET FLOW DEPTH(FEET) = 0.42 HALFSTREET FLOOD WIDTH(FEET) = 14.41 AVERAGE FLOW VELOCITY(FEET/SEC.) = 2.25 PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 0.95 STREET FLOW TRAVEL TIME(MIN.) = 1.12 Tc(MIN.) = 8.65 * 25 YEAR RAINFALL INTENSITY(INCH/HR) = 3.261 SUBAREA LOSS RATE DATA(AMC II): APARTMENTS A 1.33 0.40 0.200 32 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.40 SUBAREA AREA(ACRES) = 1.33 SUBAREA RUNOFF(CFS) = 3.81 EFFECTIVE AREA(ACRES) = 2.20 AREA-AVERAGED Fm(INCH/HR) = 0.08 AREA-AVERAGED Fp(INCH/HR) = 0.40 AREA-AVERAGED Ap = 0.20 TOTAL AREA(ACRES) = 2.2 PEAK FLOW RATE(CFS) = 6.30 END OF SUBAREA STREET FLOW HYDRAULICS: DEPTH(FEET) = 0.46 HALFSTREET FLOOD WIDTH(FEET) = 16.45 FLOW VELOCITY(FEET/SEC.) = 2.41 DEPTH*VELOCITY(FT*FT/SEC.) = 1.10 LONGEST FLOWPATH FROM NODE 2.30 TO NODE 2.50 = 452.00 FEET. FLOW PROCESS FROM NODE 2.50 TO NODE 2.60 IS CODE = 31 ELEVATION DATA: UPSTREAM(FEET) = 122.90 DOWNSTREAM(FEET) = 120.00 FLOW LENGTH(FEET) = 95.00 MANNING'S N = 0.013 ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 18.000 DEPTH OF FLOW IN 18.0 INCH PIPE IS 7.5 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 9.06 ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 6.30 PIPE TRAVEL TIME(MIN.) = 0.17 Tc(MIN.) = 8.82 LONGEST FLOWPATH FROM NODE 2.30 TO NODE 2.60 = 547.00 FEET. FLOW PROCESS FROM NODE 2.60 TO NODE 2.60 IS CODE = 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< MAINLINE Tc(MIN.) = 8.82 * 25 YEAR RAINFALL INTENSITY(INCH/HR) = 3.222 SUBAREA LOSS RATE DATA(AMC II): APARTMENTS A 1.18 0.40 0.200 32 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.40 Date: 07/18/2016 File name: 623PR25.RES Page 5 D1-32 SUBAREA AREA(ACRES) = 1.18 SUBAREA RUNOFF(CFS) = 3.34 EFFECTIVE AREA(ACRES) = 3.38 AREA-AVERAGED Fm(INCH/HR) = 0.08 AREA-AVERAGED Fp(INCH/HR) = 0.40 AREA-AVERAGED Ap = 0.20 TOTAL AREA(ACRES) = 3.4 PEAK FLOW RATE(CFS) = 9.56 FLOW PROCESS FROM NODE 2.60 TO NODE 20.00 IS CODE = 31 ELEVATION DATA: UPSTREAM(FEET) = 120.00 DOWNSTREAM(FEET) = 117.18 FLOW LENGTH(FEET) = 240.00 MANNING'S N = 0.013 DEPTH OF FLOW IN 18.0 INCH PIPE IS 13.2 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 6.90 ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 9.56 PIPE TRAVEL TIME(MIN.) = 0.58 Tc(MIN.) = 9.40 LONGEST FLOWPATH FROM NODE 2.30 TO NODE 20.00 = 787.00 FEET. FLOW PROCESS FROM NODE 20.00 TO NODE 20.00 IS CODE = 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< MAINLINE Tc(MIN.) = 9.40 * 25 YEAR RAINFALL INTENSITY(INCH/HR) = 3.101 SUBAREA LOSS RATE DATA(AMC II): APARTMENTS A 0.75 0.40 0.200 32 APARTMENTS B 0.22 0.30 0.200 56 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.38 SUBAREA AREA(ACRES) = 0.97 SUBAREA RUNOFF(CFS) = 2.64 EFFECTIVE AREA(ACRES) = 4.35 AREA-AVERAGED Fm(INCH/HR) = 0.08 AREA-AVERAGED Fp(INCH/HR) = 0.39 AREA-AVERAGED Ap = 0.20 TOTAL AREA(ACRES) = 4.4 PEAK FLOW RATE(CFS) = 11.83 FLOW PROCESS FROM NODE 20.00 TO NODE 20.00 IS CODE = 1 >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<< >>>>>AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES<<<<< TOTAL NUMBER OF STREAMS = 2 CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 2 ARE: TIME OF CONCENTRATION(MIN.) = 9.40 RAINFALL INTENSITY(INCH/HR) = 3.10 AREA-AVERAGED Fm(INCH/HR) = 0.08 AREA-AVERAGED Fp(INCH/HR) = 0.39 AREA-AVERAGED Ap = 0.20 EFFECTIVE STREAM AREA(ACRES) = 4.35 TOTAL STREAM AREA(ACRES) = 4.35 PEAK FLOW RATE(CFS) AT CONFLUENCE = 11.83 ** CONFLUENCE DATA ** STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER Date: 07/18/2016 File name: 623PR25.RES Page 6

NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 5.99 11.53 2.744 0.34( 0.07) 0.20 2.4 2.00 2 11.83 9.40 3.101 0.39( 0.08) 0.20 4.4 2.30 RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO CONFLUENCE FORMULA USED FOR 2 STREAMS. ** PEAK FLOW RATE TABLE ** STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 17.37 9.40 3.101 0.38( 0.08) 0.20 6.3 2.30 2 16.42 11.53 2.744 0.38( 0.08) 0.20 6.7 2.00 COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS: PEAK FLOW RATE(CFS) = 17.37 Tc(MIN.) = 9.40 EFFECTIVE AREA(ACRES) = 6.27 AREA-AVERAGED Fm(INCH/HR) = 0.08 AREA-AVERAGED Fp(INCH/HR) = 0.38 AREA-AVERAGED Ap = 0.20 TOTAL AREA(ACRES) = 6.7 LONGEST FLOWPATH FROM NODE 2.00 TO NODE 20.00 = 914.00 FEET. END OF STUDY SUMMARY: TOTAL AREA(ACRES) = 6.7 TC(MIN.) = 9.40 EFFECTIVE AREA(ACRES) = 6.27 AREA-AVERAGED Fm(INCH/HR)= 0.08 AREA-AVERAGED Fp(INCH/HR) = 0.38 AREA-AVERAGED Ap = 0.200 PEAK FLOW RATE(CFS) = 17.37 ** PEAK FLOW RATE TABLE ** STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 17.37 9.40 3.101 0.38( 0.08) 0.20 6.3 2.30 2 16.42 11.53 2.744 0.38( 0.08) 0.20 6.7 2.00 END OF RATIONAL METHOD ANALYSIS Date: 07/18/2016 File name: 623PR25.RES Page 7 D1-33 Date: 07/18/2016 File name: 623PR25.RES Page 8

RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE (Reference: 1986 ORANGE COUNTY HYDROLOGY CRITERION) (c) Copyright 1983-2011 Advanced Engineering Software (aes) Ver. 18.0 Release Date: 07/01/2011 License ID 1264 Analysis prepared by: ************************** DESCRIPTION OF STUDY ************************** * CITY PLAZA RESIDENTIAL * * PROPOSED HYDROLOGY - 100YR STORM EVENT * * 07-18-16 * ************************************************************************** FILE NAME: 151623PR.DAT TIME/DATE OF STUDY: 20:18 07/18/2016 USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION: --*TIME-OF-CONCENTRATION MODEL*-- USER SPECIFIED STORM EVENT(YEAR) = 100.00 SPECIFIED MINIMUM PIPE SIZE(INCH) = 18.00 SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE = 0.90 *USER-DEFINED LOGARITHMIC INTERPOLATION USED FOR RAINFALL* SLOPE OF INTENSITY DURATION CURVE(LOG(I;IN/HR) vs. LOG(Tc;MIN)) = 0.6000 USER SPECIFIED 1-HOUR INTENSITY(INCH/HOUR) = 1.3100 *ANTECEDENT MOISTURE CONDITION (AMC) III ASSUMED FOR RATIONAL METHOD* *USER-DEFINED STREET-SECTIONS FOR COUPLED PIPEFLOW AND STREETFLOW MODEL* HALF- CROWN TO STREET-CROSSFALL: CURB GUTTER-GEOMETRIES: MANNING WIDTH CROSSFALL IN- / OUT-/PARK- HEIGHT WIDTH LIP HIKE FACTOR NO. (FT) (FT) SIDE / SIDE/ WAY (FT) (FT) (FT) (FT) (n) === ===== ========= ================= ====== ===== ====== ===== ======= 1 30.0 20.0 0.018/0.018/0.020 0.67 2.00 0.0313 0.167 0.0150 GLOBAL STREET FLOW-DEPTH CONSTRAINTS: 1. Relative Flow-Depth = 0.00 FEET as (Maximum Allowable Street Flow Depth) - (Top-of-Curb) 2. (Depth)*(Velocity) Constraint = 6.0 (FT*FT/S) *SIZE PIPE WITH A FLOW CAPACITY GREATER THAN OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.* *USER-SPECIFIED MINIMUM TOPOGRAPHIC SLOPE ADJUSTMENT NOT SELECTED FLOW PROCESS FROM NODE 1.00 TO NODE 1.10 IS CODE = 21 >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< >>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< Date: 07/18/2016 File name: 623PR100.RES Page 1 D1-34 INITIAL SUBAREA FLOW-LENGTH(FEET) = 300.00 ELEVATION DATA: UPSTREAM(FEET) = 125.00 DOWNSTREAM(FEET) = 123.50 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20 SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 9.154 * 100 YEAR RAINFALL INTENSITY(INCH/HR) = 4.048 SUBAREA Tc AND LOSS RATE DATA(AMC III): Tc (MIN.) APARTMENTS A 0.01 0.40 0.200 52 9.15 APARTMENTS B 0.35 0.30 0.200 76 9.15 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.30 SUBAREA RUNOFF(CFS) = 1.29 TOTAL AREA(ACRES) = 0.36 PEAK FLOW RATE(CFS) = 1.29 FLOW PROCESS FROM NODE 1.10 TO NODE 1.10 IS CODE = 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< MAINLINE Tc(MIN.) = 9.15 * 100 YEAR RAINFALL INTENSITY(INCH/HR) = 4.048 SUBAREA LOSS RATE DATA(AMC III): APARTMENTS A 0.99 0.40 0.200 52 APARTMENTS B 0.55 0.30 0.200 76 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.36 SUBAREA AREA(ACRES) = 1.54 SUBAREA RUNOFF(CFS) = 5.51 EFFECTIVE AREA(ACRES) = 1.90 AREA-AVERAGED Fm(INCH/HR) = 0.07 AREA-AVERAGED Fp(INCH/HR) = 0.35 AREA-AVERAGED Ap = 0.20 TOTAL AREA(ACRES) = 1.9 PEAK FLOW RATE(CFS) = 6.80 FLOW PROCESS FROM NODE 1.10 TO NODE 10.00 IS CODE = 31 ELEVATION DATA: UPSTREAM(FEET) = 123.50 DOWNSTREAM(FEET) = 120.50 FLOW LENGTH(FEET) = 70.00 MANNING'S N = 0.013 ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 18.000 DEPTH OF FLOW IN 18.0 INCH PIPE IS 7.1 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 10.47 ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 6.80 PIPE TRAVEL TIME(MIN.) = 0.11 Tc(MIN.) = 9.27 LONGEST FLOWPATH FROM NODE 1.00 TO NODE 10.00 = 370.00 FEET. FLOW PROCESS FROM NODE 2.00 TO NODE 2.10 IS CODE = 21 >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< >>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< INITIAL SUBAREA FLOW-LENGTH(FEET) = 270.00 Date: 07/18/2016 File name: 623PR100.RES Page 2

ELEVATION DATA: UPSTREAM(FEET) = 125.00 DOWNSTREAM(FEET) = 124.00 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20 SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 9.319 * 100 YEAR RAINFALL INTENSITY(INCH/HR) = 4.004 SUBAREA Tc AND LOSS RATE DATA(AMC III): Tc (MIN.) APARTMENTS A 0.27 0.40 0.200 52 9.32 APARTMENTS B 0.39 0.30 0.200 76 9.32 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.34 SUBAREA RUNOFF(CFS) = 2.34 TOTAL AREA(ACRES) = 0.66 PEAK FLOW RATE(CFS) = 2.34 FLOW PROCESS FROM NODE 2.10 TO NODE 2.20 IS CODE = 31 ELEVATION DATA: UPSTREAM(FEET) = 124.00 DOWNSTREAM(FEET) = 118.90 FLOW LENGTH(FEET) = 369.00 MANNING'S N = 0.013 ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 18.000 DEPTH OF FLOW IN 18.0 INCH PIPE IS 5.5 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 5.18 ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 2.34 PIPE TRAVEL TIME(MIN.) = 1.19 Tc(MIN.) = 10.51 LONGEST FLOWPATH FROM NODE 2.00 TO NODE 2.20 = 639.00 FEET. FLOW PROCESS FROM NODE 2.20 TO NODE 2.20 IS CODE = 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< MAINLINE Tc(MIN.) = 10.51 * 100 YEAR RAINFALL INTENSITY(INCH/HR) = 3.726 SUBAREA LOSS RATE DATA(AMC III): APARTMENTS A 0.67 0.40 0.200 52 APARTMENTS B 1.03 0.30 0.200 76 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.34 SUBAREA AREA(ACRES) = 1.70 SUBAREA RUNOFF(CFS) = 5.60 EFFECTIVE AREA(ACRES) = 2.36 AREA-AVERAGED Fm(INCH/HR) = 0.07 AREA-AVERAGED Fp(INCH/HR) = 0.34 AREA-AVERAGED Ap = 0.20 TOTAL AREA(ACRES) = 2.4 PEAK FLOW RATE(CFS) = 7.77 FLOW PROCESS FROM NODE 2.20 TO NODE 20.00 IS CODE = 31 ELEVATION DATA: UPSTREAM(FEET) = 118.90 DOWNSTREAM(FEET) = 117.18 FLOW LENGTH(FEET) = 275.00 MANNING'S N = 0.013 Date: 07/18/2016 File name: 623PR100.RES Page 3 D1-35 DEPTH OF FLOW IN 18.0 INCH PIPE IS 14.5 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 5.08 ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 7.77 PIPE TRAVEL TIME(MIN.) = 0.90 Tc(MIN.) = 11.41 LONGEST FLOWPATH FROM NODE 2.00 TO NODE 20.00 = 914.00 FEET. FLOW PROCESS FROM NODE 20.00 TO NODE 20.00 IS CODE = 1 >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<< TOTAL NUMBER OF STREAMS = 2 CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE: TIME OF CONCENTRATION(MIN.) = 11.41 RAINFALL INTENSITY(INCH/HR) = 3.55 AREA-AVERAGED Fm(INCH/HR) = 0.07 AREA-AVERAGED Fp(INCH/HR) = 0.34 AREA-AVERAGED Ap = 0.20 EFFECTIVE STREAM AREA(ACRES) = 2.36 TOTAL STREAM AREA(ACRES) = 2.36 PEAK FLOW RATE(CFS) AT CONFLUENCE = 7.77 FLOW PROCESS FROM NODE 2.30 TO NODE 2.40 IS CODE = 21 >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< >>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< INITIAL SUBAREA FLOW-LENGTH(FEET) = 300.00 ELEVATION DATA: UPSTREAM(FEET) = 128.00 DOWNSTREAM(FEET) = 124.00 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20 SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 7.523 * 100 YEAR RAINFALL INTENSITY(INCH/HR) = 4.553 SUBAREA Tc AND LOSS RATE DATA(AMC III): Tc (MIN.) APARTMENTS A 0.87 0.40 0.200 52 7.52 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.40 SUBAREA RUNOFF(CFS) = 3.50 TOTAL AREA(ACRES) = 0.87 PEAK FLOW RATE(CFS) = 3.50 FLOW PROCESS FROM NODE 2.40 TO NODE 2.50 IS CODE = 62 >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>(STREET TABLE SECTION # 1 USED)<<<<< UPSTREAM ELEVATION(FEET) = 124.00 DOWNSTREAM ELEVATION(FEET) = 122.90 STREET LENGTH(FEET) = 152.00 CURB HEIGHT(INCHES) = 8.0 STREET HALFWIDTH(FEET) = 30.00 DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 20.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.018 OUTSIDE STREET CROSSFALL(DECIMAL) = 0.018 Date: 07/18/2016 File name: 623PR100.RES Page 4

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) = 5.97 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW: STREET FLOW DEPTH(FEET) = 0.45 HALFSTREET FLOOD WIDTH(FEET) = 16.05 AVERAGE FLOW VELOCITY(FEET/SEC.) = 2.39 PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 1.08 STREET FLOW TRAVEL TIME(MIN.) = 1.06 Tc(MIN.) = 8.58 * 100 YEAR RAINFALL INTENSITY(INCH/HR) = 4.208 SUBAREA LOSS RATE DATA(AMC III): APARTMENTS A 1.33 0.40 0.200 52 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.40 SUBAREA AREA(ACRES) = 1.33 SUBAREA RUNOFF(CFS) = 4.94 EFFECTIVE AREA(ACRES) = 2.20 AREA-AVERAGED Fm(INCH/HR) = 0.08 AREA-AVERAGED Fp(INCH/HR) = 0.40 AREA-AVERAGED Ap = 0.20 TOTAL AREA(ACRES) = 2.2 PEAK FLOW RATE(CFS) = 8.17 END OF SUBAREA STREET FLOW HYDRAULICS: DEPTH(FEET) = 0.49 HALFSTREET FLOOD WIDTH(FEET) = 18.24 FLOW VELOCITY(FEET/SEC.) = 2.58 DEPTH*VELOCITY(FT*FT/SEC.) = 1.26 LONGEST FLOWPATH FROM NODE 2.30 TO NODE 2.50 = 452.00 FEET. FLOW PROCESS FROM NODE 2.50 TO NODE 2.60 IS CODE = 31 ELEVATION DATA: UPSTREAM(FEET) = 122.90 DOWNSTREAM(FEET) = 120.00 FLOW LENGTH(FEET) = 95.00 MANNING'S N = 0.013 ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 18.000 DEPTH OF FLOW IN 18.0 INCH PIPE IS 8.7 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 9.70 ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 8.17 PIPE TRAVEL TIME(MIN.) = 0.16 Tc(MIN.) = 8.74 LONGEST FLOWPATH FROM NODE 2.30 TO NODE 2.60 = 547.00 FEET. FLOW PROCESS FROM NODE 2.60 TO NODE 2.60 IS CODE = 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< MAINLINE Tc(MIN.) = 8.74 * 100 YEAR RAINFALL INTENSITY(INCH/HR) = 4.160 SUBAREA LOSS RATE DATA(AMC III): APARTMENTS A 1.18 0.40 0.200 52 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.40 Date: 07/18/2016 File name: 623PR100.RES Page 5 D1-36 SUBAREA AREA(ACRES) = 1.18 SUBAREA RUNOFF(CFS) = 4.33 EFFECTIVE AREA(ACRES) = 3.38 AREA-AVERAGED Fm(INCH/HR) = 0.08 AREA-AVERAGED Fp(INCH/HR) = 0.40 AREA-AVERAGED Ap = 0.20 TOTAL AREA(ACRES) = 3.4 PEAK FLOW RATE(CFS) = 12.41 FLOW PROCESS FROM NODE 2.60 TO NODE 20.00 IS CODE = 31 ELEVATION DATA: UPSTREAM(FEET) = 120.00 DOWNSTREAM(FEET) = 117.18 FLOW LENGTH(FEET) = 240.00 MANNING'S N = 0.013 DEPTH OF FLOW IN 21.0 INCH PIPE IS 13.7 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 7.46 ESTIMATED PIPE DIAMETER(INCH) = 21.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 12.41 PIPE TRAVEL TIME(MIN.) = 0.54 Tc(MIN.) = 9.28 LONGEST FLOWPATH FROM NODE 2.30 TO NODE 20.00 = 787.00 FEET. FLOW PROCESS FROM NODE 20.00 TO NODE 20.00 IS CODE = 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< MAINLINE Tc(MIN.) = 9.28 * 100 YEAR RAINFALL INTENSITY(INCH/HR) = 4.014 SUBAREA LOSS RATE DATA(AMC III): APARTMENTS A 0.75 0.40 0.200 52 APARTMENTS B 0.22 0.30 0.200 76 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.38 SUBAREA AREA(ACRES) = 0.97 SUBAREA RUNOFF(CFS) = 3.44 EFFECTIVE AREA(ACRES) = 4.35 AREA-AVERAGED Fm(INCH/HR) = 0.08 AREA-AVERAGED Fp(INCH/HR) = 0.39 AREA-AVERAGED Ap = 0.20 TOTAL AREA(ACRES) = 4.4 PEAK FLOW RATE(CFS) = 15.41 FLOW PROCESS FROM NODE 20.00 TO NODE 20.00 IS CODE = 1 >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<< >>>>>AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES<<<<< TOTAL NUMBER OF STREAMS = 2 CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 2 ARE: TIME OF CONCENTRATION(MIN.) = 9.28 RAINFALL INTENSITY(INCH/HR) = 4.01 AREA-AVERAGED Fm(INCH/HR) = 0.08 AREA-AVERAGED Fp(INCH/HR) = 0.39 AREA-AVERAGED Ap = 0.20 EFFECTIVE STREAM AREA(ACRES) = 4.35 TOTAL STREAM AREA(ACRES) = 4.35 PEAK FLOW RATE(CFS) AT CONFLUENCE = 15.41 ** CONFLUENCE DATA ** STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER Date: 07/18/2016 File name: 623PR100.RES Page 6

NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 7.77 11.41 3.547 0.34( 0.07) 0.20 2.4 2.00 2 15.41 9.28 4.014 0.39( 0.08) 0.20 4.4 2.30 RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO CONFLUENCE FORMULA USED FOR 2 STREAMS. ** PEAK FLOW RATE TABLE ** STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 22.58 9.28 4.014 0.38( 0.08) 0.20 6.3 2.30 2 21.35 11.41 3.547 0.38( 0.08) 0.20 6.7 2.00 COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS: PEAK FLOW RATE(CFS) = 22.58 Tc(MIN.) = 9.28 EFFECTIVE AREA(ACRES) = 6.27 AREA-AVERAGED Fm(INCH/HR) = 0.08 AREA-AVERAGED Fp(INCH/HR) = 0.38 AREA-AVERAGED Ap = 0.20 TOTAL AREA(ACRES) = 6.7 LONGEST FLOWPATH FROM NODE 2.00 TO NODE 20.00 = 914.00 FEET. END OF STUDY SUMMARY: TOTAL AREA(ACRES) = 6.7 TC(MIN.) = 9.28 EFFECTIVE AREA(ACRES) = 6.27 AREA-AVERAGED Fm(INCH/HR)= 0.08 AREA-AVERAGED Fp(INCH/HR) = 0.38 AREA-AVERAGED Ap = 0.200 PEAK FLOW RATE(CFS) = 22.58 ** PEAK FLOW RATE TABLE ** STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 22.58 9.28 4.014 0.38( 0.08) 0.20 6.3 2.30 2 21.35 11.41 3.547 0.38( 0.08) 0.20 6.7 2.00 END OF RATIONAL METHOD ANALYSIS Date: 07/18/2016 File name: 623PR100.RES Page 7 D1-37 Date: 07/18/2016 File name: 623PR100.RES Page 8

Appendix C: REFERENCE MATERIALS D1-38

D1-39

D1-40

D1-41

D1-42

D1-43