HomeMy WebLinkAboutThe Garden-Sewer Capacity Memo-03-28-2019-COMPLETESEWER CAPACITY MEMORANDUM
The Garden
2902 West Coast Highway, Suite A
Newport Beach, CA 92663
PREPARED BY:
Fuscoe Engineering, Inc.
16795 Von Karman, Suite 100
Irvine, CA 92606
(949) 474-1960
Project Number:
1843-001-01
Project Manager:
Joshua Ruiz
Date Prepared:
March 28, 2019
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Sewer Capacity Memorandum
THE GARDEN
2902 West Coast Highway, Suite A, Newport Beach, CA March 28, 2019
Purpose
The purpose of this report is to present the results of the evaluation of the sewer capacity
analysis for The Garden project.
Project Site Location
The existing site is located at 2902 West Coast Highway, Suite A, in the City of Newport
Beach, CA. The site is to the northwest of the intersection of West Coast Highway (WCH)
and Riverside Avenue.
Existing Conditions
The site area is 0.3 acre. It is our understanding that the existing site is currently a
commercial/retail development. Based on our review of Sheet G-7-S of the City of
Newport Beach sewer atlas map, along with as-built sewer plans of the existing sewer
main in WCH, the wastewater of the site currently drains to the existing Orange County
Sanitation District (OCSD) 20” HDPE sewer trunk line, via an existing (estimated) 6” sewer
lateral. Since the condition of the existing sewer lateral is unknown, the City of Newport
Beach, Public Works Department is requiring the line be video-camera tested to evaluate
the condition of the lateral, and determine if lining of the existing lateral will be required.
Proposed Development
The proposed development includes demolition of the interior of the existing retail
building, and construction of The Garden restaurant. The wastewater of the site will
continue to utilize the existing 6” sewer lateral, which connects to the OCSD trunk sewer
line.
Sewer Capacity Memorandum
THE GARDEN
2902 West Coast Highway, Suite A, Newport Beach, CA March 28, 2019
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Sewer Generation Calculations (OCSD Methodology)
Since the wastewater of the site drains directly to the OCSD sewer trunk in WCH, the
sewer generation calculations have been prepared using the criteria listed in the OCSD
Engineering Design Guidelines. The calculations are based on the acreage of land use,
along with a peaking factor. Since both the existing and proposed conditions are
commercial/retail/restaurant, commercial land use has been used for both existing and
proposed condition wastewater flow rates; they are equivalent. The following are the sewer
calculations for both existing and proposed conditions:
· Site Area: 0.3 acre
· Average Daily Flow Coefficient GPD per acre (commercial (retail & restaurant)):
2262 GPD/acre
· Calculation of Average Daily Flow: 0.3 x 2262 = 679 GPD (= 0.0011 CFS)
· Peak Flow (2.5 peaking factor): 1698 GPD (= 0.00263 CFS)
The existing and proposed sewer generation calculations for the project is 0.00263 CFS.
A copy of the OCSD Design Guidelines is included as Attachment 1.
Sewer Flow-Depth Calculations
The flow-depth calculation of the peak flow was prepared using FlowMaster computer
program. The flow-depth calculation shows an existing and proposed percent-full of 5%.
The calculation demonstrates that the proposed development will not adversely impact the
existing sewer system, since the percent-full of the sewer system does not exceed 50%-full.
The calculation is included on the following page.
Sewer Capacity Memorandum
THE GARDEN
2902 West Coast Highway, Suite A, Newport Beach, CA March 28, 2019
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Sewer Capacity Memorandum
THE GARDEN
2902 West Coast Highway, Suite A, Newport Beach, CA March 28, 2019
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Conclusion
The calculations presented in this memorandum show that the proposed The Garden
restaurant will not adversely impact the existing sewer system. The depth in the existing
sewer lateral of 5%-full does not exceed the City of Newport Beach design criteria of 50%-
full. As mentioned previously, the existing lateral will be required to undergo a video-
camera evaluation to determine the condition. If a liner is required, OCSD will need to be
provided with documentation that the liner will not impede the flows in the existing 20”
HDPE trunk line in WCH.
Attachments:
1. OCSD Design Guidelines
2. Sewer Atlas G-7-S
Sewer Capacity Memo – The Garden Restaurant Newport Beach, CA
ATTACHMENT 1
OCSD Design Guidelines
Sewer Capacity Memo – The Garden Restaurant Newport Beach, CA
ATTACHMENT 2
Sewer Atlas Map G7-S
North Project Site
Bldg N1