PRELIMINARY HYDROLOGY STUDY - City of Perris

PRELIMINARY HYDROLOGY STUDY

FOR

NEW GAS STATION, CAR WASH & C-STORE

NUEVO ROAD AND MURRIETA ROAD CITY OF PERRIS, CA

Prepared For Owner/Developer:

Mr. Mark Sater Alrahman, LLC

4300 Edison Avenue Chino, CA 91710 Ph: 909.465.4101

Prepared By:

W&W LAND DESIGN CONSULTANTS

2335 W. Foothill Blvd., Suite #1 Upland, CA 91786

(909) 608-7118

March 18, 2019

Project job No. 1729

HYDROLOGY STUDY NUEVO ROAD AND MURRIETA ROAD STATION

1729 Hydrology Report

TABLE OF CONTENTS

Section I Introduction Section II Site Discussion Section III Rainfall Onsite Section IV Runoffs Description

Existing Site Conditions Proposed Site Conditions

Section V Storm Water Treatment Section VI Conclusion

Appendix A Vicinity Map

Appendix B Reference (Based on RCFC & WCD Hydrology Manual):

Hydrology Soils Group Map for Perris (C1.30) 100-year, 1-hour Precipitation Plate (D-4.4)

Soil Group B-Runoff Coefficient Curves Plate (D-5.2)

Appendix C Existing Hydrology Map Proposed Hydrology Map

Appendix D Hydrology Study Existing Conditions – 10-Year Storm Event

Existing Conditions – 100-Year Storm Event

Appendix E Hydrology Study Proposed Conditions – 10-Year Storm Event Proposed Conditions – 100-Year Storm Event



Section I Introduction The following hydrology study has been prepared for commercial gas station development project, which is located at the SE corner of Nuevo Road and Murrieta Road, in the City of Perris, County of Riverside, California. The subject site is approximately 1.75 acres’ site. An onsite storm drain systems including multiple swales, HPDE pipes and curb gutters will be constructed to convey the runoff produced by the proposed development project. Two onsite storm water quality bioretentions with pretreatment will be constructed to treat onsite storm water runoffs. The general location of the site is illustrated on the Vicinity Map in the Appendix A of this report. Section II Methodology For both, the existing and proposed conditions, the peak storm discharge for the drainage sub-areas (see hydrology maps in the Appendix C of this report) was calculated using the Riverside County Hydrology Manual (1978 April). The rational Method Equation, using CIVILD Software, was used to calculate the 10-year and 100-year storm event. The peak 10-year storm runoff is calculated to size the catch basin; parkway culverts and storm drain pipes. The peak 100-year storm runoff is calculated to demonstrate the runoff from 100-year storm event is contained within the street right-of-way. The street capacities calculations are calculated by using Flowmaster software. The stormwater Quality BMPs was calculated by using Riverside County Storm Water Quality Best Management Practice Design Handbook (2011, July) Section III Project Description Existing Site Conditions The existing tributary area is approximately 1.75-acre site tributary area of natural dirt area. There is an existing storm drain line in the northern side of the project site and it stopped before the east of Perris valley storm drain channel for future drainage uses. Lastly, the project is in Phase I ESA and should be accounted for the 100-year flood plain. Most of the site (subarea E-1) drains overland towards southeasterly sheet flow to adjacent site. Refer to the “Existing Hydrology Map” in Appendix C for an illustration of the existing drainage zones. The following table illustrates the data and results for the existing 10-year and 100-year storm events. All calculations can be found in Appendix D of this report.

Drainage Area

Area (Ac.)

10 Year Peak Flow (CFS)


Time of Concentration (Min.)

E-1 1.75 2.90 4.20 9.4

Total 1.75 2.90 4.20 Proposed site Conditions In the proposed condition, the project site can be broken down into three distinct drainage zones with total 1.75 acres of disturbed areas. Sub area A-1 to A-3 will drain to proposed water quality bioretentions through a proposed onsite drainage system. The bioretentions will be connected through a storm drainpipe to RCFC&WCD Line L with



Perris Valley Area Drainage Plan. Refer to the “Proposed Hydrology Map” in Appendix C for an illustration of the proposed drainage zones. The existing available capacity of Line L along Nuevo Road is 236 CFS which is shown on Perris, Mater Drainage Plan Map. More details of storm drains are shown in the report on the Master Drainage Plan for Perris Area. The following table illustrates the data and results for the proposed 10-year and100-year storm events. All calculations can be found in Appendix E of this report.

Drainage Area

Area (Ac.)



Time of Concentration (Min.)

A-1 0.54 1.12 1.65 6.1 Min.

A-2 & A-3 1.27 1.99 2.95 7.75 Min.

Total Area 1.75 3.11 4.60 --- In summary, total runoff will be increased after project development. After development, about 0.21 cfs will be increased per 10-year storm event and 0.40 cfs will be increased per 100-year storm event; all run off onsite will drain to the proposed storm drain system per RCFC&WCD Line L along Nuevo Road. The existing capacity of Line L is 236 cfs which satisfies the requirement of proposed condition. Bioretention Basins Volume Capacity The calculation of bioretention basin volume capacity was shown in Appendix B which is compliance with the design in WQMP report. More details of the bioretention basin are shown on a separate report of WQMP. The storm water drains to the bioretention and infiltrate into the bioretention underdrains. The underdrains connect to the catch basin and the storm water finally drain to the Line L. Findings After development, more impervious surface will cover the proposed site than before. Two proposed onsite storm drain systems will be constructed to convey the runoff produced by the proposed development project. Two onsite storm water quality bioretentions will be constructed; it will treat the first flush of runoff. Calculation of bioretentions can be found in P-WQMP report. The calculations within this report substantiate that the development can be constructed as shown on the proposed plans with no detrimental effect to surrounding properties.



APPENDIX A

VICINITY MAP



APPENDIX B

(Based on RCFC & WCD Hydrology Manual):

Hydrology Soils Group Map for Perris (C1.30) 100-year, - hour Precipitation Plate (D-4.4)

Soil Group B-Runoff Coefficient Curves Plate (D-5.2)

Julian Sung

Typewritten Text

SITE

Julian Sung

Rectangle

Julian Sung

Typewritten Text

Soil Type = B

SITE

I100 = 1.25"

Julian Sung

Rectangle



APPENDIX C

Existing Hydrology Map Proposed Hydrology Map



APPENDIX D

Hydrology Study

Existing Conditions-10 Year Storm Event Existing Conditions-100 Year Storm Event

1729EX02.out

Riverside County Rational Hydrology Program

CIVILCADD/CIVILDESIGN Engineering Software,(c) 1989 ‐ 2014 Version 9.0Rational Hydrology Study Date: 11/16/18 File:1729EX02.out

‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐1729 Perris Nuevo RoadExiting Condition10 Year Storm EventSubarea E‐1‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ ********* Hydrology Study Control Information **********

English (in‐lb) Units used in input data file

‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐

Program License Serial Number 6364

‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐Rational Method Hydrology Program based onRiverside County Flood Control & Water Conservation District1978 hydrology manual

Storm event (year) = 10.00 Antecedent Moisture Condition = 2

Standard intensity‐duration curves data (Plate D‐4.1)For the [ Perris Valley ] area used.10 year storm 10 minute intensity = 1.880(In/Hr)10 year storm 60 minute intensity = 0.780(In/Hr)100 year storm 10 minute intensity = 2.690(In/Hr)100 year storm 60 minute intensity = 1.120(In/Hr)

Storm event year = 10.0Calculated rainfall intensity data:1 hour intensity = 0.780(In/Hr)Slope of intensity duration curve = 0.4900

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++Process from Point/Station 101.00 to Point/Station 102.00**** INITIAL AREA EVALUATION ****______________________________________________________________________Initial area flow distance = 358.000(Ft.)

Page 1

1729EX02.out Top (of initial area) elevation = 22.900(Ft.) Bottom (of initial area) elevation = 21.400(Ft.) Difference in elevation = 1.500(Ft.) Slope = 0.00419 s(percent)= 0.42 TC = k(0.300)*[(length^3)/(elevation change)]^0.2 Initial area time of concentration = 9.424 min. Rainfall intensity = 1.932(In/Hr) for a 10.0 year storm COMMERCIAL subarea type Runoff Coefficient = 0.868 Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 RI index for soil(AMC 2) = 56.00 Pervious area fraction = 0.100; Impervious fraction = 0.900 Initial subarea runoff = 2.902(CFS) Total initial stream area = 1.730(Ac.) Pervious area fraction = 0.100 End of computations, total study area = 1.73 (Ac.) The following figures may be used for a unit hydrograph study of the same area.

Area averaged pervious area fraction(Ap) = 0.100 Area averaged RI index number = 56.0

Page 2

1729Ex01.out


CIVILCADD/CIVILDESIGN Engineering Software,(c) 1989 ‐ 2014 Version 9.0Rational Hydrology Study Date: 11/16/18 File:1729EX01.out

‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐1729 Perris Nuevo RoadExisting Condition100 Year Storm EventSubarea E‐1‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ ********* Hydrology Study Control Information **********


‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐


‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐Rational Method Hydrology Program based onRiverside County Flood Control & Water Conservation District1978 hydrology manual


Standard intensity‐duration curves data (Plate D‐4.1)For the [ Perris Valley ] area used.10 year storm 10 minute intensity = 1.880(In/Hr)10 year storm 60 minute intensity = 0.780(In/Hr)100 year storm 10 minute intensity = 2.690(In/Hr)100 year storm 60 minute intensity = 1.120(In/Hr)

Storm event year = 100.0Calculated rainfall intensity data:1 hour intensity = 1.120(In/Hr)Slope of intensity duration curve = 0.4900

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++Process from Point/Station 101.00 to Point/Station 102.00**** INITIAL AREA EVALUATION ****______________________________________________________________________Initial area flow distance = 358.000(Ft.)

Page 1

1729Ex01.out Top (of initial area) elevation = 22.900(Ft.) Bottom (of initial area) elevation = 21.400(Ft.) Difference in elevation = 1.500(Ft.) Slope = 0.00419 s(percent)= 0.42 TC = k(0.300)*[(length^3)/(elevation change)]^0.2 Initial area time of concentration = 9.424 min. Rainfall intensity = 2.774(In/Hr) for a 100.0 year storm COMMERCIAL subarea type Runoff Coefficient = 0.875 Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 RI index for soil(AMC 2) = 56.00 Pervious area fraction = 0.100; Impervious fraction = 0.900 Initial subarea runoff = 4.201(CFS) Total initial stream area = 1.730(Ac.) Pervious area fraction = 0.100 End of computations, total study area = 1.73 (Ac.) The following figures may be used for a unit hydrograph study of the same area.


Page 2



APPENDIX E

Hydrology Study

Proposed Conditions-10 Year Storm Event Proposed Conditions-100 Year Storm Event

10A.out


CIVILCADD/CIVILDESIGN Engineering Software,(c) 1989 ‐ 2005 Version 7.1 Rational Hydrology Study Date: 11/18/18 File:10A.out ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ 1729 PERRIS BUEO ROAD PROPOSED CONDITION 10 YEAR STORM EVENT SUBAREA A ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ ********* Hydrology Study Control Information **********


‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐


‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ Rational Method Hydrology Program based on Riverside County Flood Control & Water Conservation District 1978 hydrology manual


Standard intensity‐duration curves data (Plate D‐4.1) For the [ Perris Valley ] area used. 10 year storm 10 minute intensity = 1.880(In/Hr) 10 year storm 60 minute intensity = 0.780(In/Hr) 100 year storm 10 minute intensity = 2.690(In/Hr) 100 year storm 60 minute intensity = 1.120(In/Hr)

Storm event year = 10.0 Calculated rainfall intensity data: 1 hour intensity = 0.780(In/Hr) Slope of intensity duration curve = 0.4900

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 11.000 to Point/Station 12.000 **** INITIAL AREA EVALUATION **** ______________________________________________________________________ Initial area flow distance = 210.000(Ft.)

Page 1

10A.out Top (of initial area) elevation = 25.600(Ft.) Bottom (of initial area) elevation = 23.000(Ft.) Difference in elevation = 2.600(Ft.) Slope = 0.01238 s(percent)= 1.24 TC = k(0.300)*[(length^3)/(elevation change)]^0.2 Initial area time of concentration = 6.130 min. Rainfall intensity = 2.385(In/Hr) for a 10.0 year storm COMMERCIAL subarea type Runoff Coefficient = 0.873 Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 RI index for soil(AMC 2) = 56.00 Pervious area fraction = 0.100; Impervious fraction = 0.900 Initial subarea runoff = 1.124(CFS) Total initial stream area = 0.540(Ac.) Pervious area fraction = 0.100

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 12.000 to Point/Station 200.000 **** PIPEFLOW TRAVEL TIME (Program estimated size) **** ______________________________________________________________________ Upstream point/station elevation = 23.000(Ft.) Downstream point/station elevation = 22.500(Ft.) Pipe length = 393.00(Ft.) Manning's N = 0.013 No. of pipes = 1 Required pipe flow = 1.124(CFS) Nearest computed pipe diameter = 12.00(In.) Calculated individual pipe flow = 1.124(CFS) Normal flow depth in pipe = 8.77(In.) Flow top width inside pipe = 10.65(In.) Critical Depth = 5.35(In.) Pipe flow velocity = 1.83(Ft/s) Travel time through pipe = 3.59 min. Time of concentration (TC) = 9.72 min.

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 12.000 to Point/Station 200.000 **** CONFLUENCE OF MAIN STREAMS **** ______________________________________________________________________ The following data inside Main Stream is listed: In Main Stream number: 1 Stream flow area = 0.540(Ac.) Runoff from this stream = 1.124(CFS) Time of concentration = 9.72 min. Rainfall intensity = 1.903(In/Hr)

Page 2

10A.out Program is now starting with Main Stream No. 2

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 13.000 to Point/Station 200.000 **** INITIAL AREA EVALUATION **** ______________________________________________________________________ Initial area flow distance = 322.000(Ft.) Top (of initial area) elevation = 25.400(Ft.) Bottom (of initial area) elevation = 22.500(Ft.) Difference in elevation = 2.900(Ft.) Slope = 0.00901 s(percent)= 0.90 TC = k(0.300)*[(length^3)/(elevation change)]^0.2 Initial area time of concentration = 7.751 min. Rainfall intensity = 2.126(In/Hr) for a 10.0 year storm COMMERCIAL subarea type Runoff Coefficient = 0.870 Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 RI index for soil(AMC 2) = 56.00 Pervious area fraction = 0.100; Impervious fraction = 0.900 Initial subarea runoff = 1.517(CFS) Total initial stream area = 0.820(Ac.) Pervious area fraction = 0.100

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 13.000 to Point/Station 200.000 **** CONFLUENCE OF MAIN STREAMS **** ______________________________________________________________________ The following data inside Main Stream is listed: In Main Stream number: 2 Stream flow area = 0.820(Ac.) Runoff from this stream = 1.517(CFS) Time of concentration = 7.75 min. Rainfall intensity = 2.126(In/Hr) Program is now starting with Main Stream No. 3

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 14.000 to Point/Station 200.000 **** INITIAL AREA EVALUATION **** ______________________________________________________________________ Initial area flow distance = 349.000(Ft.) Top (of initial area) elevation = 25.700(Ft.) Bottom (of initial area) elevation = 22.500(Ft.)

Page 3

10A.out Difference in elevation = 3.200(Ft.) Slope = 0.00917 s(percent)= 0.92 TC = k(0.300)*[(length^3)/(elevation change)]^0.2 Initial area time of concentration = 7.976 min. Rainfall intensity = 2.097(In/Hr) for a 10.0 year storm COMMERCIAL subarea type Runoff Coefficient = 0.870 Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 RI index for soil(AMC 2) = 56.00 Pervious area fraction = 0.100; Impervious fraction = 0.900 Initial subarea runoff = 0.711(CFS) Total initial stream area = 0.390(Ac.) Pervious area fraction = 0.100

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 14.000 to Point/Station 200.000 **** CONFLUENCE OF MAIN STREAMS **** ______________________________________________________________________ The following data inside Main Stream is listed: In Main Stream number: 3 Stream flow area = 0.390(Ac.) Runoff from this stream = 0.711(CFS) Time of concentration = 7.98 min. Rainfall intensity = 2.097(In/Hr) Summary of stream data:

Stream Flow rate TC Rainfall Intensity No. (CFS) (min) (In/Hr)

1 1.124 9.72 1.903 2 1.517 7.75 2.126 3 0.711 7.98 2.097 Largest stream flow has longer or shorter time of concentration Qp = 1.517 + sum of Qa Tb/Ta 1.124 * 0.798 = 0.897 Qa Tb/Ta 0.711 * 0.972 = 0.691 Qp = 3.105

Total of 3 main streams to confluence: Flow rates before confluence point: 1.124 1.517 0.711

Page 4

10A.out Area of streams before confluence: 0.540 0.820 0.390

Results of confluence: Total flow rate = 3.105(CFS) Time of concentration = 7.751 min. Effective stream area after confluence = 1.750(Ac.) End of computations, total study area = 1.75 (Ac.) The following figures may be used for a unit hydrograph study of the same area.


Page 5

100A.out


CIVILCADD/CIVILDESIGN Engineering Software,(c) 1989 ‐ 2005 Version 7.1 Rational Hydrology Study Date: 11/18/18 File:100A.out ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ 1729 PERRIS BUEO ROAD PROPOSED CONDITION 100 YEAR STORM EVENT SUBAREA A ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ ********* Hydrology Study Control Information **********


‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐


‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ Rational Method Hydrology Program based on Riverside County Flood Control & Water Conservation District 1978 hydrology manual


Standard intensity‐duration curves data (Plate D‐4.1) For the [ Perris Valley ] area used. 10 year storm 10 minute intensity = 1.880(In/Hr) 10 year storm 60 minute intensity = 0.780(In/Hr) 100 year storm 10 minute intensity = 2.690(In/Hr) 100 year storm 60 minute intensity = 1.120(In/Hr)

Storm event year = 100.0 Calculated rainfall intensity data: 1 hour intensity = 1.120(In/Hr) Slope of intensity duration curve = 0.4900

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 11.000 to Point/Station 12.000 **** INITIAL AREA EVALUATION **** ______________________________________________________________________ Initial area flow distance = 210.000(Ft.)

Page 1

100A.out Top (of initial area) elevation = 25.600(Ft.) Bottom (of initial area) elevation = 23.000(Ft.) Difference in elevation = 2.600(Ft.) Slope = 0.01238 s(percent)= 1.24 TC = k(0.300)*[(length^3)/(elevation change)]^0.2 Initial area time of concentration = 6.130 min. Rainfall intensity = 3.425(In/Hr) for a 100.0 year storm COMMERCIAL subarea type Runoff Coefficient = 0.890 Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 RI index for soil(AMC 3) = 74.80 Pervious area fraction = 0.100; Impervious fraction = 0.900 Initial subarea runoff = 1.645(CFS) Total initial stream area = 0.540(Ac.) Pervious area fraction = 0.100

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 12.000 to Point/Station 200.000 **** PIPEFLOW TRAVEL TIME (Program estimated size) **** ______________________________________________________________________ Upstream point/station elevation = 23.000(Ft.) Downstream point/station elevation = 22.500(Ft.) Pipe length = 393.00(Ft.) Manning's N = 0.013 No. of pipes = 1 Required pipe flow = 1.645(CFS) Nearest computed pipe diameter = 15.00(In.) Calculated individual pipe flow = 1.645(CFS) Normal flow depth in pipe = 9.38(In.) Flow top width inside pipe = 14.52(In.) Critical Depth = 6.11(In.) Pipe flow velocity = 2.04(Ft/s) Travel time through pipe = 3.21 min. Time of concentration (TC) = 9.34 min.

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 12.000 to Point/Station 200.000 **** CONFLUENCE OF MAIN STREAMS **** ______________________________________________________________________ The following data inside Main Stream is listed: In Main Stream number: 1 Stream flow area = 0.540(Ac.) Runoff from this stream = 1.645(CFS) Time of concentration = 9.34 min. Rainfall intensity = 2.786(In/Hr)

Page 2

100A.out Program is now starting with Main Stream No. 2

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 13.000 to Point/Station 200.000 **** INITIAL AREA EVALUATION **** ______________________________________________________________________ Initial area flow distance = 322.000(Ft.) Top (of initial area) elevation = 25.400(Ft.) Bottom (of initial area) elevation = 22.500(Ft.) Difference in elevation = 2.900(Ft.) Slope = 0.00901 s(percent)= 0.90 TC = k(0.300)*[(length^3)/(elevation change)]^0.2 Initial area time of concentration = 7.751 min. Rainfall intensity = 3.053(In/Hr) for a 100.0 year storm COMMERCIAL subarea type Runoff Coefficient = 0.888 Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 RI index for soil(AMC 3) = 74.80 Pervious area fraction = 0.100; Impervious fraction = 0.900 Initial subarea runoff = 2.224(CFS) Total initial stream area = 0.820(Ac.) Pervious area fraction = 0.100

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 13.000 to Point/Station 200.000 **** CONFLUENCE OF MAIN STREAMS **** ______________________________________________________________________ The following data inside Main Stream is listed: In Main Stream number: 2 Stream flow area = 0.820(Ac.) Runoff from this stream = 2.224(CFS) Time of concentration = 7.75 min. Rainfall intensity = 3.053(In/Hr) Program is now starting with Main Stream No. 3

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 14.000 to Point/Station 200.000 **** INITIAL AREA EVALUATION **** ______________________________________________________________________ Initial area flow distance = 349.000(Ft.) Top (of initial area) elevation = 25.700(Ft.) Bottom (of initial area) elevation = 22.500(Ft.)

Page 3

100A.out Difference in elevation = 3.200(Ft.) Slope = 0.00917 s(percent)= 0.92 TC = k(0.300)*[(length^3)/(elevation change)]^0.2 Initial area time of concentration = 7.976 min. Rainfall intensity = 3.010(In/Hr) for a 100.0 year storm COMMERCIAL subarea type Runoff Coefficient = 0.888 Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 RI index for soil(AMC 3) = 74.80 Pervious area fraction = 0.100; Impervious fraction = 0.900 Initial subarea runoff = 1.043(CFS) Total initial stream area = 0.390(Ac.) Pervious area fraction = 0.100

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 14.000 to Point/Station 200.000 **** CONFLUENCE OF MAIN STREAMS **** ______________________________________________________________________ The following data inside Main Stream is listed: In Main Stream number: 3 Stream flow area = 0.390(Ac.) Runoff from this stream = 1.043(CFS) Time of concentration = 7.98 min. Rainfall intensity = 3.010(In/Hr) Summary of stream data:

Stream Flow rate TC Rainfall Intensity No. (CFS) (min) (In/Hr)

1 1.645 9.34 2.786 2 2.224 7.75 3.053 3 1.043 7.98 3.010 Largest stream flow has longer or shorter time of concentration Qp = 2.224 + sum of Qa Tb/Ta 1.645 * 0.830 = 1.365 Qa Tb/Ta 1.043 * 0.972 = 1.014 Qp = 4.603

Total of 3 main streams to confluence: Flow rates before confluence point: 1.645 2.224 1.043

Page 4

100A.out Area of streams before confluence: 0.540 0.820 0.390

Results of confluence: Total flow rate = 4.603(CFS) Time of concentration = 7.751 min. Effective stream area after confluence = 1.750(Ac.) End of computations, total study area = 1.75 (Ac.) The following figures may be used for a unit hydrograph study of the same area.


Page 5

PRELIMINARY HYDROLOGY STUDY - City of Perris

Documents

Transcript of PRELIMINARY HYDROLOGY STUDY - City of Perris