HomeMy WebLinkAboutCT 05-10; Poinsettia Properties The Tides; Potable and Recycled Water System Analysis; 2010-10-16DEXTER WILSON ENGINEERING, INC.
WATER • WASTEWATER • RECYCLED WATER
CONSULTING ENGINEERS RECORD COPY
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Initial 'Sate
POTABLE AND RECYCLED
WATER SYSTEM ANALYSIS
FOR
CARLSBAD TRACT 05-10
September 16, 2010
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2234 FARADAY AVENUE • CARLSBAD, CA 92008 • (760) 438-4422
POTABLE AND RECYCLED
WATER SYSTEM ANALYSIS
FOR
CARLSBAD TRACT 05-10
September 16, 2010
Prepared by:
Dexter Wilson Engineering, Inc.
2234 Faraday Avenue
Carlsbad, CA 92008
Job No. 505-095
DEXTER WILSON ENGINEERING, INC.
DEXTER S. WILSON, P.E.
ANDREW M. OVEN, P.E.
STEPHEN M. NIELSEN, P.E.
DIANE H. SHAUGHNESSY, P.E.
September 16, 2010 505-095
Rick Engineering Company
5620 Friars Road
San Diego, CA 92110-2596
Attention: Craig Kahlen, Project Manager
Subject:Carlsbad Tract 05-10 Water Analysis
Introduction
This letter-report summarizes our evaluation of the potable and recycled water system that will
serve the proposed Carlsbad Tract 05-10 project in Carlsbad. The project is located along the
west side of Lowder Lane, just south of Poinsettia Lane. The project is bounded to the west by
Interstate 5 and to the south and east by existing development. The existing property where
the project is to be located is currently vacant. The project proposes a residential subdivision
with 27 single family residential lots.
The project is within the 318 Zone of the Carlsbad Municipal Water District system. This zone
serves the coastal development in southern Carlsbad and is formed by several existing pressure
reducing stations. The closest pressure reducing stations to the project are the Poinsettia and
Las Ondas facilities. The Poinsettia station is set for an output hydraulic gradeline of 309 feet
and the Las Ondas pressure reducing station is set for an output hydraulic gradeline of 322
feet. Both stations are supplied from the 375 Zone.
2234 FARADAY AVENUE • CARLSBAD, CA 92OO8 • (760)438-4422 • FAX (76O) 438-0173
Craig Kahlen
September 16, 2010
Water Service Design Criteria«•
** The basic design criteria used in this study are in accordance with the District's March 2003
** Water Master Plan. The water distribution system needs to provide a minimum residual
•m pressure of 40 psi under peak hour demand conditions and a minimum residual pressure of 20
M psi under maximum day demand plus fire flow conditions. The fire flow requirement for single
family residential development is 1,500 gpm for 2 hours.
Projected Water Demand
The 2003 Master Plan (Table 6-2) uses an average day demand factor of 550 gpd per unit. For
the proposed 27 units on this project, this equates to an average projected water demand of
14,850 gpd.
Existing Water System
The existing 318 Zone facilities serve the entire south coastal area and the water lines are well
looped in this area. The primary lines that will supply the project are the existing 12-inch lines
in Poinsettia Lane and Lowder Lane. Figure 1 provides the location of the project and existing
water facilities in the vicinity of the project.
Water System Overview
The pad elevations of the Carlsbad Tract 05-10 project range from 117 feet to 133 feet. With
service from the 318 Zone, the maximum static pressures within the site will be 80 psi to 87 psi.
This pressure will result in good domestic service to the project.
The critical component of the water system for this project is the ability to meet a maximum
day demand plus 1,500 gpm fire flow scenario. The 2003 Carlsbad Water Master Plan
performed extensive computer modeling to determine the adequacy of the existing system and
to meet buildout development conditions. The masterplan does not identify any upgrades to
the system to meet existing or future demand conditions in ths area of the water system.
DEXTER WILSON ENGINEERING, INC. PAGE 2
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INTERSTATE 5 OFFRAMP
NOT TO SCALE
FIGURE 1
PROPOSED POTABLE
WATER SYSTEM
Craig Kahlen
September 16, 2010
To supply the onsite water system, an 8-inch water line loop is proposed with connections to the
existing 12-inch line in Lowder Lane at two locations. This system will supply two onsite fire
hydrants. Domestic water service to each lot will be provided by a separate water service.
Figure 1 provides the location of proposed water facilities to serve the project.
Recycled Water
The City of Carlsbad will require the use of recycled water onsite for the irrigation of common
areas within the project. There is an existing 24-inch line in Poinsettia Lane and a 4-inch line
in Lowder Lane that can supply the project. This system is part of the City's 385 Zone recycled
water system. The project proposes a single point of connection to the line in Lowder Lane to
supply an irrigation meter. Downstream of the irrigation meter, onsite recycled water lines will
be private and sized by the landscape architect.
With service from the 385 Zone, the maximum static pressure at the onsite irrigation meter will
be approximately 110 psi. This will be adequate to serve the onsite irrigation needs of the
project. Figure 2 graphically shows the location of the existing and proposed recycled water
facilities in the vicinity of the project.
Conclusion
Based on our evaluation of the water system, the existing 318 Zone system will be able to
supply adequate domestic and fire protection service to the project. The project can receive
service by connecting to the existing 12-inch water line in Lowder Lane and constructing an
onsite water loop to supply the proposed fire hydrants and domestic services. An onsite recycled
water service will be supplied by connecting to the existing line in Lowder Lane.
If you have any questions, please let us know.
Dexter Wilson Engineering, Inc.
Stephen M. Nielsen
SMN:ck
DEXTER WILSON ENGINEERING, INC. PAGE A
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INTERSTATE 5 OFFRAMP
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FIGURE 2
PROPOSED RECYCLED
WATER SYSTEM
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