PC - Item 3A - Exhibit E - Appendix D - Hydrology ReportCal Land Engineering, Inc.
dba Quartech Consultants
Geotechnical, Environmental, and Civil Engineering
Hydrology Report
PROVIDES DATE 05/08/2020
JOB ADDRESS:
8589 GARVEY AVE. AND 3001 WALNUT GOVE AVE.
ROSEMEAD, CA 91770
BY
CAL LAND ENGINEERING, INC.
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Introduction
The project site is located at the northwest corner of Walnut Grove Ave and Garvey Ave,
City of Rosemead.
The project is relatively flat, existing drainage flow drains to southeast direction from
northwest. The proposed development runoff will be collected in the basement storage
and infiltrated by drywell then overflowed to street through parkway drain. Hydraulic
calculation is based on 50-year storm event. There is no off-site drainage for this project.
The proposed development is to construct a mix-use residential and commercial
building.
Existing Hydrology Study
A-ex
Soil Type: 003
Total Area = 1.057 acres
Percent Impervious = 93.62%
Average Rainfall Depth = 6.20 in.
Using Tc Calculator
Tc = 5 min.
Qex = 3.4234 cfs
Proposed Hydrology Study
A-1
Soil Type: 003
Total Area = 1.057 acres
Percent Impervious = 97.48%
Average Rainfall Depth = 6.20 in.
Using Tc Calculator
Tc = 5 min.
Qpro = 3.4812 cfs
Qpro - Qex = 3.4812 – 3.4234 = 0.0578 cfs
Parkway Drain
Q= 3.765 cfs > 3.4812 cfs OK for 30”x4” parkway drain.
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