The Residences At Berkeley Plaza

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SAN FRANCISCO

855 Folsom St, Unit 142

San Francisco, CA 94107

Tel: (415) 837-1336

Fax: (415) 837-1354

OAKLAND

1330 Broadway, Suite 952

Oakland, CA 94612

Tel: (510) 893-1668

Fax: (510) 893-1669

MEMORANDUM

Date: 2/06/2013 Pages:

4

To: Luis Arambula From:

Paul Boumann

Company: MVEI Company: Telamon Engineering Consultants

Inc.

Phone No: (949) 809-3380 Phone No: (415) 837-1336

CC: Mennor Chan

Project: The Residences At Berkeley Plaza

Subject: C3 Storm Water Discharge Calculations

I. Background:

Telamon Engineering Consultants (TECI) calculated the area and volume required to treat storm water

run-off for 80% of the annual runoff from the project site. The calculations were based on the Alameda

County Clean Water Program, “C.3 Storm Water Technical Guidance”. Since the roof areas will be

treated separately from the court yard areas, these two areas were evaluated independently of each other.

II. Evaluation:

The following tables show the Roof area and Court Yard area requirements along with the flow rates and

volumes generated by a 2 year storm (0.2 inches/hour) for the bio-treatment areas of the subject

conceptual designs. The volumes were calculated using Table 5-3, “ Unit Basin Storage Volumes in

Inches for 80 Percent Capture Using 48-hour Drawdowns”. The “Volume Treatment Value” was

calculated using Region 5 San Francisco, with a mean annual precipitation of 21 inches/year and using

22.5 inches/year for the City of Berkeley. See attached Table 5-3 and “Mean Seasonal Isohyets” map in

Appendices. The “Volume Treatment Value” calculated to 0.78 inches for net areas to be treated. See

“Volume Treatment Calculations” in Appendices.

T E L A M O N E N G I N E E R I N G C O N S U L T A N T S I N C

The residences At Berkeley Plaza

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Treatment Areas:

AREA AREA

TREATED

sf

AREA

TREATED

Acres

REQUIRED

TREATEMENT

AREA

Sf

PROPOSED

TREATEMENT

AREA

sf

Roof 24,193 0.56 968

Roof Landscape

Area

2,900

Court Yard 12,822 0.29 513

Flow Through

Planters

1,196

Flow Rates and Volumes:

III. Assumptions:

The following assumptions were made when generating the calculations above:

1. The landscape areas on the roof will be used as bio-treatment areas. See Exhibit “A” in

Appendices.

2. The flow through planters within the court yard area will be used as bio-treatment areas. See

Exhibit “B” in Appendices.

IV. Conclusion:

Based on the above calculations and assumptions, the Conceptual designs for “The Residences At

Berkeley Plaza” should be able to meet the C3 Storm Water Discharge requirements. The Required

Treatment Area for the roof is 968 square feet and Exhibit “A” shows roughly 2,900 square feet of

landscape area that can potentially be used for bio-treatment area. The required Treatment Area for the

court yard is 513 square feet and Exhibit “B” shows roughly 1,196 square feet of flow through planter

area that can potentially be used for bio-treatment area. The average depth, based on volume, for the bio-

treatment areas are reasonable.

AREA TOTAL

AREA

Sf

LANDSCAPE

AREA

sf

NET

AREA

Sf

AREA

Acres

C CA SUM

CA

UNIT

INTENSITY

FLOW

Q

cfs

Vol.

cf

AVG

Depth

Roof 24,193 2,900 21,193 0.49 0.7 0.34

Roof

Landscape

2,900 2,900 0.07 0.1 .007

Total 0.35 0.2 0.07 1,384 0.48+/-

Court

Yard

12,822 1,196 11,626 0.27 0.7 0.19

Flow

Through

1,196 1,196 0.03 0.1 0.003

Total 0.19 0.2 0.04 756 0.63+/-

T E L A M O N E N G I N E E R I N G C O N S U L T A N T S I N C

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The above calculations, assumptions and conclusions are based on Conceptual design plans and therefore

the above results may vary as the design plans become more refined during the design process.

T E L A M O N E N G I N E E R I N G C O N S U L T A N T S I N C

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REFERENCES

1. Table 5-3

2. Mean Seasonal Isohyets map

3. Exhibit “A”

4. Exhibit “B”

5. Volume Treatment Calculation

Paul.b

Text Box

EXHIBIT "B" Flow Through Planters = 1,196 sf Court Yard Area = 12,822 sf