TECHNICAL APPENDIX G PRELIMINARY DRAINAGE REPORT

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T

ECHNICAL

A

PPENDIX

G

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PRELIMINARY DRAINAGE REPORT

For

PLANNING AREA 12 INNOVATION PARK OFFICE

COMPLEX

(00808253-PMPC)

VESTING TENTATIVE PARCEL MAP 2019-177

(00816106-PTP)

IRVINE, CALIFORNIA

Prepared For:

Irvine Company Office Properties

111 Innovation

Irvine, CA 92617

Prepared By:

38 Technology Drive

Irvine, California 92618

(949) 923-6000

Contact Person: Vicky Ito

Job Number: 2042486930

Prepared: 02/24/2020

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This report presents the design considerations, methodology, and results of drainage analyses performed for the proposed Planning Area 12 Master Plan (00808253-PMPC and Vesting Tentative Parcel Map 2019-177) storm drain improvementslocated in the City of Irvine. This report addresses the drainage issues directly associated with the project as well as any adjacent offsite drainage issues directly impacting the site.

Hydrologic calculations were performed for the proposed condition of this project to assess the impact of the future development.

This report assesses the proposed drainage condition and provides preliminary storm drain pipe alignments, pipe sizes, and peak flow rates pursuant to the development site plan. The proposed storm drain is sized for the 25-year peak flow rate for the proposed development that connects to two separate existing storm drain pipes, an existing 42-inch/48-inch RCP storm drain line that runs parallel to the south property line and ultimately discharges to an existing storm drain pipe in the adjacent golf course property, and an 18-inch RCP line that runs within the proposed private road on the north side of the property and discharges into the adjacent golf course property. According to as-built drawings, the existing storm drain lines in the golf course property are a 48-inch reinforced concrete pipe and an 18-inch reinforced concrete pipe with design flows of 149.8 cfs and 6.8 cfs, respectively. The hydrology analysis has concluded that under post-development conditions, the 48-inch reinforced concrete pipe will accept an anticipated 155.65 cfs. The hydrology analysis for the 18-inch storm drain pipe has been performed per a separate report (Hydraulic Study for Spectrum 7 – Planning Area 12 Private Backbone Storm Drain 00788702-GPRE) and no changes are made in this report.

Based on results from the 25-year peak flow rate hydrology analysis, an anticipated flowrate of 155.65 cfs will ultimately discharge to the existing 48-inch storm drain at the edge of the Oak Creek Golf Course. Although record drawings show that the existing 48-inch pipe was designed to intercept a flowrate of 149.8 cfs, the overage is within the 10 percent tolerance acceptable within standard engineering practice. Additionally, the hydraulic grade line for the existing 48-inch pipe shown on record drawings indicate that there is capacity within the pipe to accept additional flows.

2. PROJECT DESCRIPTION

A. BACKGROUND / PRE-PROJECT SITE DESCRIPTION

The project site is located in the City of Irvine, County of Orange, and State of California. See Figure 1 for Vicinity Map The development area is bounded by Oak Creek Golf Course to the west, the Orange County Transportation Authority (OCTA)/Metrolink railroad to the south, previously approved Master Plan – 00775712-PMPC and Sand Canyon Avenue to the east, and I-5 Freeway to the north.. Access to the site is currently provided from Walnut Avenue to the west and Burt Road at Sand Canyon Avenue to the east.

The proposed project will be developed, in part, over the 36.5-acre site previously occupied by vacant land and a nominal area (approximately 4.2 acres) previously analyzed with Drainage Report for Innovation Park Phase 2 – 00813586-GPRE. See pre-project condition and existing condition hydrology maps located in the appendix.

Under existing conditions, the vacant land is in mass grade condition (mass grading was initiated in September 2019 under Grading Permit No. 00795717-RG). Prior to the recent mass grading, the site was previously used for agricultural purposes and then as a stockpile site. The topography of the mass graded site ranges from 180’ at the northeasterly corner

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the southwesterly corner of the property to a temporary desilting basin. There is a ridge near the west property line. Runoff west of the ridge drains to an earthen channel that runs along the west property line to a second smaller desilting basin located in the southwest corner. The two desilting basins discharge to the existing 48-inch storm at the edge of the Oak Creek Golf Course via corrugated steel pipes. The existing 48-inch storm drain is maintained by the City of Irvine and crosses under Jeffrey Road via an existing RCP. Beyond Jeffrey Road, the flow continues in existing facilities known as Como Channel (F06P03) until ultimately reaching the Peters Canyon Wash (F06) and then San Diego Creek (F05).

All of Planning Area 12 (including the project site) is located within the regional watershed of San Diego Creek. The entire San Diego Creek watershed consists of approximately 122 square miles that ultimately drains into Upper Newport Bay. As mentioned above, the project is tributary to the existing Como Channel (Orange County Flood Control District Facility No. F06P03).

The entire site lies within a Zone X pursuant to the flood insurance rate map (Community No. 060222, Map No. 06059C0292J, effective December 3, 2009). Zone X represents an area outside the 500-year flood plain; therefore a 100-year hydrologic analysis was not performed. See Figure 2 for a copy of the Flood Insurance Rate Map.

B. SCOPE OF PROJECT / PROPOSED IMPROVEMENTS

The proposed project is for the development of an office complex with associated parking facilities.

1. PROPOSED GRADING

The proposed grading will range between 0.5% to 4% slopes for paved areas. The landscape areas will range between 1% to 40%. It is anticipated about fifteen buildings along with associated parking lots will be constructed and arranged in a campus style manner.

2. PROPOSED DRAINAGE FACILITIES

The project site is divided into two (2) major tributaries connecting to two (2) existing conveyance systems as shown in the hydrology exhibit provided in the Appendix. The stormwater from the majority of the project site, drainage area “A”, will be conveyed to the proposed private storm drain facilities within the project site and will eventually discharge to the existing public storm drain system (48-inch RCP) that runs along the A.T. & S.F./Metrolink Railroad to the southwest. Drainage area “B” includes runoff from the proposed private roadway that is conveyed by curb inlets and underground private storm drain where most of it discharges into the proposed extended detention basin. Two curb inlets on the westerly end of the private road will bypass the basin and connect directly into the basin outlet pipe. The basin outlet pipe then connects to the existing 18-inch RCP located to the south, which meanders through the golf course property. The proposed extended detention basin attenuates proposed condition flows so as not to exceed the capacity of the existing 18-inch RCP point of connection. Drainage Area B was included in the previous Hydraulic Study for Spectrum 7 – Planning Area 12 Private Backbone Storm Drain (00788702-GPRE). There will be no changes made to Drainage Area B and no additional analyses will be performed for Drainage Area B in this report.

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C. DESIGN CRITERIA

1. DEVELOPED CONDITIONS

The storm drain improvements will be designed to provide protection at the level required by the City of Irvine.

The drainage facilities will be designed to accommodate the following events:

Storm drain main line: ... 25-year Storm Event Project Site’s Soil: Type B per Orange CountyHydrology Manual. See Figure 3 for copy of Soils Map.

3. METHODOLOGY A. HYDROLOGY

Hydrologic calculations performed for the project are in conformance with the Orange County Hydrology Manual dated 1986.

The following is a brief explanation of input data used in the hydrologic calculations: Hydrologic analyses were prepared for the proposed developed condition to calculate the 25-year peak runoff using the Rational Method procedure. The analyses were performed in conjunction with the preparation of the vesting tentative parcel map. The existing soil type (Type B) was determined with the use of the soils map provided in the Orange County Hydrology Manual. A copy of the Soils Map is provided as Figure 3 with this report. AES HydroWin Rational Method software, by Advanced Engineering Software (AES), was utilized for these calculations.

Refer to report appendices for rational method calculations and proposed condition hydrology map for the 25-year storm event.

B. HYDRAULICS

1. CONDUIT HYDRAULICS

The FLOWMASTER computer program was used to preliminarily calculate the flow conditions in the proposed storm drain systems. Pipe slopes were estimated based on standard depths and the conceptual grading study.

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4. SUMMARY OF RESULTS

A. DRAINAGE AREA AND FLOW RATE SUMMARY

Drainage Area ID Node No. to Node No. 25‐Year Peak Flow Rate (cfs) Estimated Pipe Size (in) A 103 ‐ 104 15.19 24 A 104 ‐ 105 18.47 24 A 105 ‐ 106 19.96 24 A 106 ‐ 107 27.16 24 A 107 ‐ 108 30.59 30 A 303 ‐ 304 5.45 18 A 304 ‐ 305 6.38 18 A 305 ‐ 306 7.80 18 A 306 ‐ 307 8.86 18 A 307 ‐ 308 10.19 24 A 308 ‐ 309 12.54 24 A 309 ‐ 310 13.70 24 A 310 ‐ 311 15.57 24 A 311 ‐ 312 17.63 24 A 312 ‐ 313 28.49 30 A 313 ‐ 314 30.17 30 A 402 ‐ 403 0.47 12 A 403 ‐ 404 12.33 24 A 404 ‐ 312 13.89 24

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1. VICINITY MAP

2. FLOOD INSURANCE RATE MAP

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v:\2042\active\2042486920\design\drain\20190620_preliminary_drainage_study\20190619_preliminary_drainage_report.docx 6. APPENDIX

• PRE-PROJECT CONDITION MAP

• EXISTING CONDITION HYDROLOGY MAP

• PROPOSED CONDITION PRELIMINARY HYDROLOGY MAP

• RATIONAL METHOD HYDROLOGIC RESULTS

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EXISTING CONDITION HYDROLOGY MAP

PER DRAINAGE REPORT FOR INNOVATION PARK PHASE 1 (00797738-GPRE) AND DRAINAGE REPORT FOR

INNOVATION PARK PHASE 2 (00788702-GPRE) PROPOSED CONDITION HYDROLOGY MAP

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IP25P100

____________________________________________________________________________ **************************************************************************** RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE

Stantec ************************** DESCRIPTION OF STUDY ************************** * INNOVATION PARK * * PROPOSED CONDITION FOR 25-YR STORM EVENT * * SYSTEM 100 * ************************************************************************** FILE NAME: IP25P100.DAT

TIME/DATE OF STUDY: 15:15 06/19/2019

============================================================================ USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION:

============================================================================ --*TIME-OF-CONCENTRATION

USER SPECIFIED STORM EVENT(YEAR) = 25.00 SPECIFIED MINIMUM PIPE SIZE(INCH) = 12.00

SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE = 0.95 *DATA BANK RAINFALL USED*

*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

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

Existing Hydrology Study

25-year

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FLOW PROCESS FROM NODE 100.00 TO NODE 101.00 IS CODE = 21

>>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<

>>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<<

============================================================================ INITIAL SUBAREA FLOW-LENGTH(FEET) = 257.00

ELEVATION DATA: UPSTREAM(FEET) = 199.00 DOWNSTREAM(FEET) = 197.50 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20

SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 7.827 * 25 YEAR RAINFALL INTENSITY(INCH/HR) = 3.743 SUBAREA Tc AND LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS Tc LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN (MIN.) COMMERCIAL B 1.61 0.30 0.100 56 7.83 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.30

SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.100 SUBAREA RUNOFF(CFS) = 5.38

TOTAL AREA(ACRES) = 1.61 PEAK FLOW RATE(CFS) = 5.38

**************************************************************************** FLOW PROCESS FROM NODE 101.00 TO NODE 102.00 IS CODE = 51

>>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<<

>>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<<

============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 197.50 DOWNSTREAM(FEET) = 192.40 CHANNEL LENGTH THRU SUBAREA(FEET) = 383.00 CHANNEL SLOPE = 0.0133 CHANNEL BASE(FEET) = 0.00 "Z" FACTOR = 48.000

MANNING'S FACTOR = 0.015 MAXIMUM DEPTH(FEET) = 1.00 * 25 YEAR RAINFALL INTENSITY(INCH/HR) = 3.236

SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN COMMERCIAL B 1.57 0.30 0.100 56 SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.30

SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.100

TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 7.65 TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 2.78 AVERAGE FLOW DEPTH(FEET) = 0.24 TRAVEL TIME(MIN.) = 2.29 Tc(MIN.) = 10.12

SUBAREA AREA(ACRES) = 1.57 SUBAREA RUNOFF(CFS) = 4.53

EFFECTIVE AREA(ACRES) = 3.18 AREA-AVERAGED Fm(INCH/HR) = 0.03 AREA-AVERAGED Fp(INCH/HR) = 0.30 AREA-AVERAGED Ap = 0.10

TOTAL AREA(ACRES) = 3.2 PEAK FLOW RATE(CFS) = 9.18 END OF SUBAREA CHANNEL FLOW HYDRAULICS:

DEPTH(FEET) = 0.26 FLOW VELOCITY(FEET/SEC.) = 2.90

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>>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<

>>>>>USING USER-SPECIFIED PIPESIZE (EXISTING ELEMENT)<<<<<

============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 179.56 DOWNSTREAM(FEET) = 179.16 FLOW LENGTH(FEET) = 65.00 MANNING'S N = 0.013

ASSUME FULL-FLOWING PIPELINE

PIPE-FLOW VELOCITY(FEET/SEC.) = 5.19

PIPE FLOW VELOCITY = (TOTAL FLOW)/(PIPE CROSS SECTION AREA) GIVEN PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 9.18

PIPE TRAVEL TIME(MIN.) = 0.21 Tc(MIN.) = 10.33

LONGEST FLOWPATH FROM NODE 100.00 TO NODE 103.00 = 705.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 103.00 TO NODE 103.00 IS CODE = 1

>>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<<

============================================================================ TOTAL NUMBER OF STREAMS = 2

CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE: TIME OF CONCENTRATION(MIN.) = 10.33

RAINFALL INTENSITY(INCH/HR) = 3.20 AREA-AVERAGED Fm(INCH/HR) = 0.03 AREA-AVERAGED Fp(INCH/HR) = 0.30 AREA-AVERAGED Ap = 0.10

EFFECTIVE STREAM AREA(ACRES) = 3.18 TOTAL STREAM AREA(ACRES) = 3.18

PEAK FLOW RATE(CFS) AT CONFLUENCE = 9.18

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS Tc LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN (MIN.) COMMERCIAL B 0.82 0.30 0.100 56 9.97

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SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.30 SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.100 SUBAREA RUNOFF(CFS) = 2.39

>>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<

============================================================================ MAINLINE Tc(MIN.) = 9.97

* 25 YEAR RAINFALL INTENSITY(INCH/HR) = 3.265 SUBAREA LOSS RATE DATA(AMC II):

SUBAREA AREA(ACRES) = 0.97 SUBAREA RUNOFF(CFS) = 2.82 EFFECTIVE AREA(ACRES) = 1.79 AREA-AVERAGED Fm(INCH/HR) = 0.03 AREA-AVERAGED Fp(INCH/HR) = 0.30 AREA-AVERAGED Ap = 0.10

TOTAL AREA(ACRES) = 1.8 PEAK FLOW RATE(CFS) = 5.21 **************************************************************************** FLOW PROCESS FROM NODE 103.00 TO NODE 103.00 IS CODE = 1

>>>>>AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES<<<<<

PEAK FLOW RATE(CFS) AT CONFLUENCE = 5.21 ** CONFLUENCE DATA **

STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 9.18 10.33 3.199 0.30( 0.03) 0.10 3.2 100.00 2 5.21 9.97 3.265 0.30( 0.03) 0.10 1.8 104.00 RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO

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** PEAK FLOW RATE TABLE **

STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 14.25 9.97 3.265 0.30( 0.03) 0.10 4.9 104.00 2 14.28 10.33 3.199 0.30( 0.03) 0.10 5.0 100.00 COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 14.28 Tc(MIN.) = 10.33

TOTAL AREA(ACRES) = 5.0

DEPTH OF FLOW IN 24.0 INCH PIPE IS 13.8 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 7.67

GIVEN PIPE DIAMETER(INCH) = 24.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 14.28

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============================================================================ MAINLINE Tc(MIN.) = 9.73

TOTAL AREA(ACRES) = 0.9 PEAK FLOW RATE(CFS) = 2.63 **************************************************************************** FLOW PROCESS FROM NODE 105.00 TO NODE 105.00 IS CODE = 1

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STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 14.25 10.05 3.250 0.30( 0.03) 0.10 4.9 104.00 1 14.28 10.41 3.185 0.30( 0.03) 0.10 5.0 100.00 2 2.63 9.73 3.310 0.30( 0.03) 0.10 0.9 106.00 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 16.68 9.73 3.310 0.30( 0.03) 0.10 5.6 106.00 2 16.83 10.05 3.250 0.30( 0.03) 0.10 5.7 104.00 3 16.81 10.41 3.185 0.30( 0.03) 0.10 5.9 100.00 COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

ASSUME FULL-FLOWING PIPELINE

PIPE-FLOW VELOCITY(FEET/SEC.) = 5.36

PIPE FLOW VELOCITY = (TOTAL FLOW)/(PIPE CROSS SECTION AREA) GIVEN PIPE DIAMETER(INCH) = 24.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 16.83

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TIME OF CONCENTRATION(MIN.) = 11.23 RAINFALL INTENSITY(INCH/HR) = 3.05 AREA-AVERAGED Fm(INCH/HR) = 0.03 AREA-AVERAGED Fp(INCH/HR) = 0.30 AREA-AVERAGED Ap = 0.10

TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 6.33 TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 1.89

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AVERAGE FLOW DEPTH(FEET) = 0.26 TRAVEL TIME(MIN.) = 0.66 Tc(MIN.) = 8.06

STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 16.68 10.92 3.100 0.30( 0.03) 0.10 5.6 106.00 1 16.83 11.23 3.051 0.30( 0.03) 0.10 5.7 104.00 1 16.81 11.60 2.996 0.30( 0.03) 0.10 5.9 100.00

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2 7.49 8.21 3.642 0.30( 0.03) 0.10 2.3 108.00 RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO

STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 22.25 8.21 3.642 0.30( 0.03) 0.10 6.5 108.00 2 23.04 10.92 3.100 0.30( 0.03) 0.10 7.9 106.00 3 23.09 11.23 3.051 0.30( 0.03) 0.10 8.0 104.00 4 22.96 11.60 2.996 0.30( 0.03) 0.10 8.1 100.00 COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

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END OF SUBAREA CHANNEL FLOW HYDRAULICS:

STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 22.25 8.96 3.468 0.30( 0.03) 0.10 6.5 108.00 1 23.04 11.67 2.986 0.30( 0.03) 0.10 7.9 106.00 1 23.09 11.98 2.942 0.30( 0.03) 0.10 8.0 104.00 1 22.96 12.34 2.893 0.30( 0.03) 0.10 8.1 100.00 2 10.77 9.12 3.432 0.30( 0.03) 0.10 3.5 112.00 RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO

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STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 32.94 8.96 3.468 0.30( 0.03) 0.10 9.9 108.00 2 33.07 9.12 3.432 0.30( 0.03) 0.10 10.1 112.00 3 32.40 11.67 2.986 0.30( 0.03) 0.10 11.4 106.00 4 32.31 11.98 2.942 0.30( 0.03) 0.10 11.5 104.00 5 32.03 12.34 2.893 0.30( 0.03) 0.10 11.6 100.00 COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

============================================================================ MAINLINE Tc(MIN.) = 9.25

TOTAL AREA(ACRES) = 11.9 PEAK FLOW RATE(CFS) = 33.07 NOTE: PEAK FLOW RATE DEFAULTED TO UPSTREAM VALUE

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SUBAREA RUNOFF(CFS) = 4.10

STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 32.94 9.44 3.367 0.30( 0.03) 0.10 10.2 108.00 1 33.07 9.61 3.333 0.30( 0.03) 0.10 10.4 112.00 1 32.40 12.15 2.918 0.30( 0.03) 0.10 11.7 106.00 1 32.31 12.46 2.877 0.30( 0.03) 0.10 11.8 104.00 1 32.03 12.83 2.830 0.30( 0.03) 0.10 11.9 100.00 2 4.10 8.33 3.612 0.30( 0.03) 0.10 1.3 117.00 RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO

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STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 35.33 8.33 3.612 0.30( 0.03) 0.10 10.3 117.00 2 36.76 9.44 3.367 0.30( 0.03) 0.10 11.5 108.00 3 36.85 9.61 3.333 0.30( 0.03) 0.10 11.6 112.00 4 35.71 12.15 2.918 0.30( 0.03) 0.10 12.9 106.00 5 35.57 12.46 2.877 0.30( 0.03) 0.10 13.1 104.00 6 35.23 12.83 2.830 0.30( 0.03) 0.10 13.2 100.00 COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

>>>>>MAIN-STREAM MEMORY COPIED ONTO MEMORY BANK # 1 <<<<<

============================================================================ **************************************************************************** FLOW PROCESS FROM NODE 120.00 TO NODE 121.00 IS CODE = 21

SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 7.613 * 25 YEAR RAINFALL INTENSITY(INCH/HR) = 3.802

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SUBAREA Tc AND LOSS RATE DATA(AMC II):

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PIPE-FLOW(CFS) = 9.28

STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 12.12 10.72 3.133 0.30( 0.03) 0.10 4.0 120.00 2 9.28 10.61 3.151 0.30( 0.03) 0.10 3.3 124.00 RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO

STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 21.35 10.61 3.151 0.30( 0.03) 0.10 7.3 124.00 2 21.35 10.72 3.133 0.30( 0.03) 0.10 7.3 120.00 COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

>>>>>CONFLUENCE MEMORY BANK # 1 WITH THE MAIN-STREAM MEMORY<<<<<

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** MAIN STREAM CONFLUENCE DATA **

STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 21.35 10.61 3.151 0.30( 0.03) 0.10 7.3 124.00 2 21.35 10.72 3.133 0.30( 0.03) 0.10 7.3 120.00 LONGEST FLOWPATH FROM NODE 120.00 TO NODE 119.00 = 1280.00 FEET. ** MEMORY BANK # 1 CONFLUENCE DATA **

STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 35.33 8.64 3.539 0.30( 0.03) 0.10 10.3 117.00 2 36.76 9.75 3.306 0.30( 0.03) 0.10 11.5 108.00 3 36.85 9.91 3.275 0.30( 0.03) 0.10 11.6 112.00 4 35.71 12.46 2.878 0.30( 0.03) 0.10 12.9 106.00 5 35.57 12.77 2.837 0.30( 0.03) 0.10 13.1 104.00 6 35.23 13.13 2.792 0.30( 0.03) 0.10 13.2 100.00 LONGEST FLOWPATH FROM NODE 100.00 TO NODE 119.00 = 1952.10 FEET. ** PEAK FLOW RATE TABLE **

STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE 1 54.87 8.64 3.539 0.30( 0.03) 0.10 16.2 117.00 2 57.34 9.75 3.306 0.30( 0.03) 0.10 18.1 108.00 3 57.59 9.91 3.275 0.30( 0.03) 0.10 18.4 112.00 4 57.89 10.61 3.151 0.30( 0.03) 0.10 19.2 124.00 5 57.84 10.72 3.133 0.30( 0.03) 0.10 19.3 120.00 6 55.30 12.46 2.878 0.30( 0.03) 0.10 20.2 106.00 7 54.88 12.77 2.837 0.30( 0.03) 0.10 20.4 104.00 8 54.23 13.13 2.792 0.30( 0.03) 0.10 20.5 100.00 TOTAL AREA(ACRES) = 20.5

COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

>>>>>CLEAR MEMORY BANK # 1 <<<<<

============================================================================ **************************************************************************** FLOW PROCESS FROM NODE 119.00 TO NODE 127.00 IS CODE = 41

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