HomeMy WebLinkAboutAttachment 4a - L1 Overview of Water Service (3)
Appendix L1
Overview of Water Service
DEXTER WILSON ENGINEERING, INC.
WATER WASTEWATER RECYCLED WATER
CONSULTING ENGINEERS
OVERVIEW OF WATER SERVICE
FOR
SUNBOW II, PHASE 3
September 2020
(760) 438-4422
TABLE OF CONTENTS
PAGE NO.
CHAPTER 1 INTRODUCTION ................................................................................... 1-1
PHYSICAL SETTING ............................................................................ 1-1
PROPOSED LAND USE PLAN ............................................................ 1-1
WATER SERVICE ................................................................................. 1-3
PURPOSE OF STUDY ........................................................................... 1-3
CHAPTER 2 PLANNING CRITERIA AND
PROJECTED WATER DEMANDS....................................................... 2-1
Duty Factors and Peaking Factors ........................................... 2-1
System Pressures ....................................................................... 2-2
Pump Station .............................................................................. 2-2
Reservoirs .................................................................................... 2-2
Projected Water Demands ......................................................... 2-3
CHAPTER 3 WATER SUPPLY ................................................................................... 3-1
Urban Water Management Planning Act ................................ 3-1
Senate Bills 610 and 221 ........................................................... 3-1
Urban Water Management Plans ............................................. 3-2
REGIONAL AND LOCAL WATER SUPPLY ...................................... 3-3
Metropolitan Water District ...................................................... 3-3
San Diego County Water Authority (SDCWA) ........................ 3-4
Otay Water District .................................................................... 3-8
POTABLE WATER ................................................................................ 3-9
624 Zone ...................................................................................... 3-9
CHAPTER 4 RECOMMENDED WATER FACILITIES ............................................ 4-1
RECYCLED WATER ............................................................................. 4-1
APPENDIX A LAND USE PROJECT DESCRIPTION
i
TABLE OF CONTENTS
LIST OF TABLES
PAGE NO.
TABLE 2-1 WATER DUTY FACTORS ........................................................................... 2-1
TABLE 2-2 SUNBOW II, PHASE 3
PROJECTED POTABLE WATER DEMANDS ......................................... 2-3
TABLE 2-3 SUNBOW II, PHASE 3
PROJECTED RECYCLED WATER DEMANDS ...................................... 2-3
TABLE 3-1 PROJECTED NORMAL YEAR WATER SUPPLIES (AFY) .................... 3-5
TABLE 3-2 AVERAGE/NORMAL WATER YEAR SUPPLY AND
DEMAND ASSESSMENT (AFY) ................................................................ 3-6
TABLE 3-3 SINGLE DRY WATER YEAR SUPPLY AND
DEMAND ASSESSMENT (AFY) ................................................................ 3-7
TABLE 3-4 MULTIPLE DRY WATER YEAR SUPPLY
AND DEMAND ASSESSMENT (AFY) ...................................................... 3-7
ii
TABLE OF CONTENTS
LIST OF FIGURES
PAGE NO.
FIGURE 1-1 LOCATION MAP .................................................................................... 1-2
FIGURE 3-1 EXISTING WATER FACILITIES ....................................................... 3-10
FIGURE 4-1 PROPOSED POTABLE AND RECYCLED WATER SYSTEMS ........ 4-3
iii
ABBREVIATIONS
ac - acre
AF - acre-foot
AMSL - above mean sea level
cfd - community facilities district
cfs - cubic feet per second
CRA - Colorado River Aqueduct
GDP/SRP - General Development Plan/Subregional Plan
gpd - gallons per day
gpf - gallons per flush
gpm - gallons per minute
HOA - homeowners association
IID - Imperial Irrigation District
LAFCO - Local Agency Formation Commission
mgd - million gallons per day
MAF - million acre-feet
MF - multi-family land use designation
MWD - Metropolitan Water District of Southern California
psi - pounds per square inch
SAMP - subarea master plan
SF - single family land use designation
SDCWA - San Diego County Water Authority
SWP - State Water Project
UWMP - Urban Water Management Plan
USEFUL CONVERSIONS
1 acre-foot = 325,829 gallons
1 mgd = 1,000,000 gallons/day
1 cfs = 448.8 gpm
1 cubic foot = 7.48 gallons
1 mgd = 694.4 gpm
iv
CHAPTER 1
INTRODUCTION
With the exception of Planning Area 23, the Sunbow project has been fully developed. This
report provides an overview of water service for the Sunbow II, Phase 3 (formerly Planning
Area 23) project. This report will estimate water demands, outline regional water facilities to
be constructed, and recommend onsite facilities to accommodate project demands. The report
includes an overview of water supplies in the region and recommends water facilities specific to
the needs of the Sunbow II, Phase 3 project.
PHYSICAL SETTING
The Sunbow II, Phase 3 project site is located in the City of Chula Vista, along the south side of
Olympic Parkway. There are two proposed points of access to the project off Olympic Parkway
that have not changed from the 1998 Sunbow Specific Planning Area (SPA) plan. Topography
on the property ranges in elevation from abut 250 feet to 470 feet. Developed pads on the
property will range in elevation from approximately 370 feet to 420 feet. Figure 1-1 presents a
location map for the project.
PROPOSED LAND USE PLAN
The Sunbow II, Phase 3 site has historically been planned as an approximately 64 acre
industrial park. The proposed Sunbow II, Phase 3 Amendment includes a Chula Vista General
Plan Amendment, a Sunbow General Development Plan Amendment, a Sunbow Sectional
Planning Area Amendment, Rezone and tentative map necessary to implement the proposed
project. A more detailed land use description is provided in Appendix A.
DEXTER WILSON ENGINEERING, INC. PAGE 1-1
The Proposed Project includes 718 multi-family units on approximately 44 acres within the
135.7 acre area designated Sunbow II, Phase 3 in the 1998 Sunbow SPA Site Utilization Plan.
The Proposed Project includes four unique residential product types in two- and three-story
units. Open space requirements are satisfied in a variety of forms, including private read
yards, porches, decks and patios as well as common useable open space comprised of common
courtyards, landscaped areas and the 0.9 acre community purpose facility. The Proposed
Project also includes approximately 5.9 acres for backbone streets and 63.6 acres designated
MSCP Preserve open space.
WATER SERVICE
The Sunbow II, Phase 3 project site is within the boundaries of the Otay Water District (OWD)
for water service. For its potable water, the OWD relies solely on the San Diego County Water
Authority (SDCWA), a member of the Metropolitan Water District (MWD). A large portion of
the water used in the SDCWA area is imported from MWD, which transports its water supply
through the State Water Project (SWP) and the Colorado River Aqueduct (CRA). The SDCWA
transports filtered water to near the Lower Otay Reservoir, just south of the property.
The OWD has existing and planned facilities in the vicinity of the project and water service can
be provided by expanding the existing system. In particular, water service will be provided by
the 624 Pressure Zone (624 Zone) within the Central Area System of the OWD. The 624 Zone
is fed from SDCWA aqueduct connections that supply 624 Zone Reservoirs. This report will
provide recommendations for expanding the 624 Zone as needed to provide water service to the
Sunbow II, Phase 3 project.
PURPOSE OF STUDY
This report provides an overview of water service for the proposed Sunbow II, Phase 3 project.
This document is prepared as a supporting document for the projects Specific Plan and EIR.
The developers of the project will be required to prepare a private water system analysis
concurrent with final engineering plans to establish domestic water service and water sizes and
to size the private fire supply system to meet fire flow requirements.
DEXTER WILSON ENGINEERING, INC. PAGE 1-3
CHAPTER 2
PLANNING CRITERIA AND
PROJECTED WATER DEMANDS
This chapter presents the planning criteria used to evaluate the water system for the Sunbow
II, Phase 3 project. The criteria are utilized for analysis of the existing water system as well as
for sizing of proposed improvements and expansions to the existing system to accommodate
demands in the study area. Unless otherwise noted, this criteria is taken from the OWD 2015
Water Facilities Master Plan Update.
Duty Factors and Peaking Factors
Table 2-1 presents the duty factors used in projecting the total average demand for the Sunbow
II, Phase 3 project. The required fire flows and durations are also listed. Per correspondence
with the Chula Vista Fire Department, the estimated fire flow requirement for the Sunbow II,
Phase 3 project is 3,000 gpm. Actual fire flow requirements will be determined as site specific
details such as building footprints and construction materials become available.
TABLE 2-1
WATER DUTY FACTORS
Unit Required Required Fire
Land Use Designation Domestic Fire Flow Flow Duration
Demand (gpm) (hours)
Multi-Family (>10 DU/AC) 170 gpd/unit 3,000 3
Park/CPF 1,900 gpd/ac ------ -------
To convert average day potable water demands to maximum day demands, Figure 4-1-2 (Curve
2) from the Water Agency Standards was utilized. To convert average day potable water
demands to peak hour demands, Figure 4-1-1 (Curve 2) from the Water Agency Standards was
used.
DEXTER WILSON ENGINEERING, INC. PAGE 2-1
System Pressures
Generally, the potable water distribution system is designed to maintain static pressures
between 65 psi and 200 psi. This criteria is used to initially divide a project between water
service zones. The potable water distribution system has been designed to yield a minimum of
40 psi residual pressure at any location under peak hour demand flows, and a minimum
residual pressure of 20 psi during maximum day demand plus fire flow conditions. Potable
water mains are sized to maintain a maximum velocity of 10 feet per second under a maximum
day plus fire flow scenario and a maximum velocity of 6 feet per second under peak hour flow
conditions.
Pump Station
Pump stations are sized for a firm capacity equivalent to the maximum day demand of the zone
being served and all higher zones supplied by the pump station. Firm capacity is defined as
the pumping capacity of the station when one pumping unit is out of service. To allow OWD
flexibility to avoid pumping during peak electricity times, the pumps will be sized to allow
pumping to occur over a 16 hour period.
Reservoirs
Reservoir storage consists of operational storage, emergency storage, and fire flow storage.
Operational storage is to be equivalent to 30 percent of the maximum daily demand for the
area being served. Emergency storage is to be equivalent to 100 percent of the maximum daily
demand for the area be served. Fire flow storage is to be based on the highest fire flow and
duration required within the service area. Where multiple reservoirs are provided within a
pressure zone, the fire flow storage requirement applies to the whole zone and not to each
individual reservoir.
DEXTER WILSON ENGINEERING, INC. PAGE 2-2
Projected Water Demands
Table 2-2 provides the projected potable water demand for the Sunbow II, Phase 3 project. The
total estimated average potable water use is 0.12 mgd. This demand will be supplied from
OWDs 624 Zone as discussed in Chapter 4. Recycled water will be used for irrigation of
manufactured slopes and common areas. Table 2-3 provides the projected recycled water
demands for the project.
TABLE 2-2
SUNBOW II, PHASE 3
PROJECTED POTABLE WATER DEMANDS
Total Average
Land Use Gross Quantity, Water Duty
Neighborhood Water
Designation Acres Units Factor
Demand, GPD
R-1 MF Residential 8.5 131 170 gpd/unit 22,270
R-2 MF Residential 4.6 73 170 gpd/unit 12,410
R-3 MF Residential 8.1 108 170 gpd/unit 18,360
R-4 MF Residential 8.2 118 170 gpd/unit 20,060
R-5 MF Residential 7.1 104 170 gpd/unit 17,680
R-6 MF Residential 7.6 184 170 gpd/unit 31,280
TOTAL 718 122,060
TABLE 2-3
SUNBOW II, PHASE 3
PROJECTED RECYCLED WATER DEMANDS
Irrigation Total Average
Land Use Designation Quantity
Factor Demand, GPD
Irrigated Slopes 12 ac 1,900 gpd/ac 22,800
Private Open Space/CPF 0.9 ac 1,900 gpd/ac 1,710
TOTAL 24,510
DEXTER WILSON ENGINEERING, INC. PAGE 2-3
CHAPTER 3
WATER SUPPLY
Urban Water Management Planning Act
In 1983, the Legislature enacted the Urban Water Management Planning Act (California
Water Code sections 10610 through 10656), which requires every urban water supplier that
provides water to 3,000 or more customers, or over 3,000 acre feet (af) of water annually, to
make every effort to ensure the appropriate level of reliability in its water service to meet the
needs of its customers during normal, dry, and multiple-dry years. The UWMP is required in
order for a water supplier to be eligible for the Department of Water Resources (DWR)
administered state grants, loans, and drought assistance. The UWMP provides information on
water use, water resources, recycled water, water quality, reliability planning, demand
management measures, best management practices, and water shortage contingency planning
for a specified service area or territory.
Senate Bills 610 and 221
California Water Code Sections 10631, 10656, 10910, 10911, 10912, and 10915 are referred to
as Senate Bill (SB) 610 and Government Code Sections 65867.5, 66455.3, and 66473.7 are
referred to as SB 221. SB 610 and SB 221 amended state law, effective January 1, 2002,
intending to improve the link between the information on water supply availability and certain
land use decisions made by cities and counties. SB 610 requires that the water purveyor of the
public water system prepare a water supply assessment to be included in the California
Environmental Quality Act (CEQA) environmental documentation and approval process of
certain proposed projects. SB 221 requires affirmative written verification from the water
purveyor of the public water system that sufficient water supplies are to be available for
certain residential subdivision of property. SB 610 requires a city or county to evaluate
whether water supplies will be sufficient to meet the projected water demand for certain
jectsherwise subject to the requirement of CEQA. SB 610 provides its own
Section 10912.
DEXTER WILSON ENGINEERING, INC. PAGE 3-1
Urban Water Management Plans
The California Urban Water Management Planning Act requires that each urban water
supplier providing water for municipal purposes, either to more than 3,000 customers, or more
than 3,000 acre-feet of water annually, must prepare, adopt, and update a UWMP at least once
every five years on or before December 31, in years ending in five and zero. This applies to
MWD, SDCWA, and its member agencies, including OWD, that serve unincorporated San
Diego County. The intent of an UWMP is to present information on water supply, water
usage/demand, recycled water, and water use efficiency programs in a respective water
distr service area. An UWMP also serves as a valuable resource for planners and policy
makers over a 25 year time frame.
The UWMP process ensures that water supplies are being planned to meet future growth.
UWMPs are developed to manage the uncertainties and variability of multiple supply sources
and demands over the long term. Water agencies and districts update their demand and
supply estimates based on the most recent San Diego Association of Governments (SANDAG)
forecast approximately every five years to coincide with preparation of their UWMPs. The most
current supply and demand projections are contained in the 2015 UWMPs of MWD, SDCWA,
and OWD. SDCWA member districts rely on the UWMPs and Integrated Resources Plans
(IRPs) of MWD and the Regional Water Facilities Master Plan of SDCWA for documentation of
supplies available to meet projected demands.
Normal year, single-dry year, and multiple-dry year 2015 UWMP supply and demand
assessments for MWD, SDCWA, and OWD are intended to describe the water supply reliability
and vulnerability to seasonal or climatic conditions, to the extent practical. Normal water years
are considered to be years that experience average rainfall for the respective district. Single-
dry water years are considered one year drought events. Multiple-dry water years refer to a
series of below average rainfall for particular areas (i.e., multiple drought year conditions).
Projections for multiple-dry years are made in five year increments. In the 2015 UWMPs,
MWD, SDCWA and all SDCWA member agencies, including OWD, that serve unincorporated
San Diego County determined that adequate water supplies would be available to serve
existing service areas under normal year, single-dry year, and multiple-dry year conditions
through the year 2040.
DEXTER WILSON ENGINEERING, INC. PAGE 3-2
REGIONAL AND LOCAL WATER SUPPLY
Metropolitan Water District
MWD supplies water to approximately 18.7 million people in a 5,200-square mile service area
that includes portions of Ventura, Los Angeles, Orange, San Bernardino, Riverside, and San
Diego coun6 member agencies. Supply and demand projection
information for MWD is included in its 2015 Regional UWMP, adopted in May 2016
long-term strategy for a sustainable water supply is outlined in its Integrated Resources Plan
(IRP), updated approximately every five years, and last updated in October 2015 IRP
identifies a mix of resources (imported and local) that will provide 100 percent reliability for
full-service demands through the attainment of regional targets set for conservation, local
supplies, SWP supplies, Colorado River supplies, groundwater banking, and water transfers
through the year 2040. SDCWA is the largest MWD agency in terms of delivery, purchasing
approximately 25 percent of MWD's water. MWD gets its water from two sources. The first
source is the Colorado River, which is connected to -county service area through a
242-mile aqueduct. The aqueduct system is known as the Central Valley Project (CVP). The
CVP is operated by the U.S. Bureau of Reclamation. The second source is water from northern
California, which supplies water through a series of dams, aqueducts, pipelines, and other
facilities known as the State Water Project (SWP). The SWP is operated by the California
Department of Water Resources (DWR). From the Colorado River Agreement (CRA), MWD is
apportioned 550,000 acre-feet of water per year (AFY) from the Colorado River. Despite this
low apportionment, MWD was able to transport up to 1.2 million acre-feet (MAF) through the
CRA in past years by relying on unused apportionments from Arizona, Nevada, and California
agricultural agencies. However, because MWD's firm water supply from the CRA is only
550,000 AF that is the number planning agencies must rely on for development. To
supplement this supply, MWD also has several existing programs and programs being
developed in cooperation with other agencies.
From the SWP, MWD is contractually entitled to receive 1,911,000 AF of water; however, the
level of SWP supply development, state and federal environmental regulations, and other
factors have restricted and, in some cases, reduced actual amount of available SWP water. As
a result of these and other limitations, MWD estimates that actual SWP supplies will be
701,000 AF in a dry year and 566,000 AF during multiple dry years, with Delta improvements.
DEXTER WILSON ENGINEERING, INC. PAGE 3-3
In May 2016, the MWD adopted its 2015 Regional UWMP, which is an update to its prior 2010
Regional UWMP. In its 2015 UWMP, MWD evaluated water supply reliability, over a 20-year
period, for average, single-dry, and multiple-dry years. To complete its most recent water
supply reliability assessment, MWD developed estimates of total retail demands for the region,
factoring in the impacts of conservation. After estimating demands, the water reliability
analysis identified current supplies and supplies under development to meet projected
demands. MWD's reliability assessment showed that MWD can maintain reliable water
supplies to meet projected demands through the year 2040. MWD also identified buffer
supplies, including other SWP groundwater storage and transfers, which could serve to supply
additional water needs. Appendix A-3 to the MWD 2015 Regional UWMP contains detailed
justifications for the sources of supply projected to meet water demands in the region, including
Colorado River Aqueduct deliveries (Colorado River supplies) and California Aqueduct
deliveries (SWP supplies).
San Diego County Water Authority (SDCWA)
The SDCWA service area covers approximately 951,000 acres and encompasses the western
third of San Diego County. SDCWA has 24 member agencies, 15 of which provide water to
unincorporated areas of San Diego County. The SDCWA is responsible for ensuring a safe and
reliable water supply to support the regios economy and the quality of life for three million
residents. Because of th-arid climate and limited local water supplies, SDCWA
has historically imported between 70 and 95 percent of the water used in the San Diego region
from MWD. In 2008, MWD provided 71 percent of the San Diego region's water supply. Most
of this water is obtained from the Colorado River and the SWP through a system of pipes,
aqueducts, and associated facilities. Through development of new local water supply sources
such as the Carlsbad Desalination Plant, SDCWA has become increasingly less reliant on
MWD water supplies in recent years.
Both MWD and SDCWA provide water supplies to their member agencies in order to meet
projected water demand based upon regional population forecasts. The San Diego Association
of Governments (SANDAG) is responsible for providing and updating land use planning and
demographic forecasts for San Diego County. MWD and SDCWA update their water demand
and supply estimates based on the most recent SANDAG forecasts approximately every five
years to coincide with preparation of their respective UWMPs.
DEXTER WILSON ENGINEERING, INC. PAGE 3-4
In June 2016, the SDCWA adopted its 2015 UWMP, updating the previously adopted 2010
UWMP. Sections 4, 5, and 6 of SDCWA15 UWMP contain documen
existing and planned water supplies, including MWD supplies (imported Colorado River water
and SWP water), SDCWA supplies, and local member agency supplies (surface water
reservoirs, water recycling, groundwater, and groundwater recovery). SDCWA supplies include
(1) IID water transfer supplies, (2) Supplies from conservation projects to line the All-American
Canal and the Coachella Canal, located in Imperial and Coachella Valleys, and (3) development
of a seawater desalination facility at the Encina Power Plant in Carlsbad, which is anticipated
to produce 56,000 AFY of additional water supplies. (See Table 3-1 below.)
Additionally, since 1980, approximately 5 percent to 30 percent of the member agencies water
has come from local sources, primarily from surface water reservoirs as indicated in Table 3-1.
Recycled water and groundwater recovery projects are growing in importance in the region,
and water conservation efforts have also made SDCWA member agencies less dependent on
imported water.
TABLE 3-1
PROJECTED NORMAL YEAR WATER SUPPLIES (AFY)
WATER SOURCE 2020 2025 2030 2035 2040
Water Authority Supplies
IID Water Transfer 190,000 200,000 200,000 200,000 200,000
Supply from MWD 136,002 181,840 207,413 224,863 248,565
Coachella Canal and All American
80,200 80,200 80,200 80,200 80,200
Canal Lining Projects
50,000 50,000 50,000 50,000 50,000
Regional Seawater Desalination
Member Agency Supplies
Surface Water 51,580 51,480 51,380 51,280 51,180
Water Recycling 40,459 43,674 45,758 46,118 46,858
Groundwater 17,940 19,130 20,170 20,170 20,170
Seawater Desalination 6,000 6,000 6,000 6,000 6,000
Brackish Groundwater Recovery 12,100 12,500 12,500 12,500 12,500
718,773
TOTAL PROJECTED SUPPLIES 587,581 648,124 676,721 694,431
Source: San Diego County Water Authority 2015 Urban Water Management Plan.
DEXTER WILSON ENGINEERING, INC. PAGE 3-5
Section 9 15 UWMP evaluates water supply reliability in average, single-dry,
and multiple-dry upply reliability assessment, SDCWA
concluded that water supplies would be sufficient through 2040. (See section below regarding
Summary of Water Supplies and Demand, and Tables 3-2 through 3-4.)
Based on the imported and member agency local water sources discussed above, SDCWA
estimates that it, along with member agency local sources will be able to supply 587,581 AF of
water in 2020, as demonstrated in Table 3-1 above. Therefore, according to the MWD and
SDCWA 2015 UWMPs, there is available water to meet all of the region's anticipated demand,
including development of the Sunbow II, Phase 3 project, in average/normal and dry water
years, as demonstrated in Table 3-2, Table 3-3 and Table 3-4, below. A Water Supply
Assessment and Verification Report will need to be prepared for the Sunbow II, Phase 3 project
by OWD to further detail the water supply assumptions and findings of OWD, SDCWA, and
MWD. The reason that supplies exactly meet demands in Table 3-2 is that SDCWA only
imports the amount of water necessary to meet demand. In Tables 3-3 and 3-4, years that
show a deficit would require the use of water storage offsets and management actions to
balance demand and supplies. These tables simply indicate that SDCWA has adequate supply
to meet projected demands
TABLE 3-2
AVERAGE/NORMAL WATER YEAR SUPPLY AND DEMAND
ASSESSMENT (AFY)
MEMBER AGENCY SUPPLIES 2020 2025 2030 2035 2040
Surface Water 51,580 51,480 51,380 51,280 51,180
Water Recycling 40,459 43,674 45,758 46,188 46,858
Groundwater 17,940 19,130 20,170 20,170 20,170
Brackish Groundwater Recovery 12,100 12,500 12,500 12,500 12,500
Seawater Desalination 6,000 6,000 6,000 6,000 6,000
Potable Reuse 3,300 3,300 3,300 3,300 3,300
WATER AUTHORITY SUPPLIES
IID Water Transfer 190,000 200,000 200,000 200,000 200,000
Supply from MWD 136,002 181,840 207,413 224,863 248,565
Coachella Canal and All American
80,200 80,200 80,200 80,200 80,200
Canal Lining Projects
Carlsbad Desalination Plant 50,000 50,000 50,000 50,000 50,000
TOTAL PROJECTED SUPPLIES 587,581 648,124 676,721 694,431 718,773
1
TOTAL ESTIMATED DEMANDS 587,581 648,124 676,721 694,431 718,773
DIFFERENCE 0 0 0 0 0
1
With Conservation.
Source: San Diego County Water Authority 2015 Urban Water Management Plan.
DEXTER WILSON ENGINEERING, INC. PAGE 3-6
TABLE 3-3
SINGLE DRY WATER YEAR SUPPLY AND DEMAND
ASSESSMENT (AFY)
MEMBER AGENCY SUPPLIES 2020 2025 2030 2035 2040
Surface Water 6,004 6,004 6,004 6,004 6,004
Water Recycling 40,459 43,674 45,758 46,188 46,858
Groundwater 15,281 15,281 15,281 15,281 15,281
Brackish Groundwater Recovery 12,100 12,500 12,500 12,500 12,500
Seawater Desalination 6,000 6,000 6,000 6,000 6,000
Potable Reuse 3,300 3,300 3,300 3,300 3,300
WATER AUTHORITY SUPPLIES
IID Water Transfer 190,000 200,000 200,000 200,000 200,000
Supply from MWD 263,340 264,740 263,340 260,680 258,720
Coachella Canal and All American
80,200 80,200 80,200 80,200 80,200
Canal Lining Projects
Carlsbad Desalination Plant 50,000 50,000 50,000 50,000 50,000
TOTAL PROJECTED SUPPLIES 666,684 681,699 682,383 680,083 678,863
1
TOTAL ESTIMATED DEMANDS 629,198 694,147 725,006 743,990 770,765
2
DIFFERENCE 37,486 (12,448) (42,623) (63,907) (91,902)
1
With Conservation.
2
Potential shortages would be met from carryover storage and management actions.
Source: San Diego County Water Authority 2015 Urban Water Management Plan.
TABLE 3-4
MULTIPLE DRY WATER YEAR SUPPLY AND DEMAND
ASSESSMENT (AFY)
Near Term Long Term
Scenario
2017 2018 2019 2036 2037 2038
Multiple Dry Years
Demands 491,000 495,910 500,869 749,030 756,521 764,086
Supply 525,710 558,634 586,587 720,576 678,564 642,327
Potential Surplus or
34,710 62,724 85,718 (28,454) (77,957) (121,759)
1
(Shortage)
1
Potential shortages would be offset through carryover storage and management actions.
Source: San Diego County Water Authority 2015 Urban Water Management Plan.
DEXTER WILSON ENGINEERING, INC. PAGE 3-7
Otay Water District
Once water is made available by SDCWA, it is transferred across San Diego County in two
aqueducts containing five large-diameter pipelines. The First Aqueduct includes Pipelines 1
and 2, and the Second Aqueduct includes Pipelines 3, 4 and 5. The OWD maintains several
connections to Pipeline 4, which delivers filtered water from the MWD filtration plant at Lake
Skinner in Riverside County.
In San Diego County, OWD provides water services to southern El Cajon, La Mesa, Rancho
San Diego, Jamul, Spring Valley, Bonita, eastern Chula Vista, and Otay Mesa along the
international border with Mexico. OWD covers approximately 80,000 acres, and has
approximately 47,000 connections. OWD has approximately 709 miles of pipelines, 24 pump
stations, and 40 reservoirs with a total storage capacity of 226 million gallons (mg). OWD
provides approximately 90 percent of its water service to residential land uses, and 10 percent
to commercial and industrial land uses. Average annual consumption for OWD is
approximately 30,000 af. OWD maintains five major systems to supply and deliver water,
which include Hillsdale, Regulatory, La Presa, Central, and Otay Mesa.
In addition, OWD Flow Control Facility No. 14 and the Jamacha Road Pipeline delivers
filtered water from the R.M. Levy Water Treatment Plant which is owned and operated by the
Helix Water District. However, this connection currently supplies water to the north portion of
OWD only. Furthermore, OWD maintains a connection to the City of San Diegos water system
in Telegraph Canyon Road and has an agreement which allows the District to receive water
from the Lower Otay Filtration Plant.
In June 2016, OWhe updated OWD 2015 UWMP. Sections 2,
3, and 4 of the 2015 UWMP provides an overrvice area, its current water
supply sources, supply reliability, water demands, measures to reduce water demand, and
planned water supply projects and programs. Section 5 of the 2015 UWMP
water service reliability assessment. This section states that the level of reliability is based on
WD and SDCWA and that these agencies
have determined they will be able to meet potable water demands through 2040, during normal
and dry year conditions. According to the 2015 UWMP, OWD currently relies on MWD and
SDCWA for its potable supply, and OWD has worked with these agencies to prepare consistent
demand projectionervice area.
DEXTER WILSON ENGINEERING, INC. PAGE 3-8
POTABLE WATER
The OWD will supply water to the Sunbow II, Phase 3 project from the 624 Zone of the
District's Central Area System. The 624 Zone accesses water from the SDCWA aqueduct by
Otay Flow Control Facilities Number 10 and 12, which fill 624 Pressure Zone reservoirs.
Water is then distributed within the 624 Zone and pumped to the 711 and 980 Zone storage
and distribution systems.
To receive potable water service, the Sunbow II, Phase 3 project will need to expand the
existing 624 Zone. The following details the existing potable water facilities located in the
vicinity of the project.
624 Zone
There are three existing reservoirs in the 624 Zone, located along the SDCWA aqueduct east of
the project. The 624-1 Zone reservoir is located near the SDCWA Otay No. 12 aqueduct
connection and has a capacity of 12.4 million gallons (MG). The 624-2 Zone reservoir is located
north of Otay Lakes Road near the SDCWA Otay No. 10 connection and has a capacity of 8.1
MG. The 624-3 Zone reservoir is located just south of the 624-1 Zone reservoir and has a
capacity of 30 MG.
There are major transmission lines from these reservoirs to convey water to the various 624
Zone use areas and to supply 711 Zone and 980 Zone pump stations. In the vicinity of the
Sunbow II, Phase 3 project, there are 16-inch transmission lines in Medical Center Drive,
Paseo Ladera, and Olympic Parkway. Figure 3-1 provides the location of existing 624 Zone
regional facilities in the vicinity of the project.
DEXTER WILSON ENGINEERING, INC. PAGE 3-9
CHAPTER 4
RECOMMENDED WATER FACILITIES
The Sunbow II, Phase 3 project site will receive water service by expanding the existing 624
Zone water system. Figure 4-1 provides the recommended water facilities for the project. As
discussed previously, a private water system analysis will be prepared prior to review and
approval of final engineering improvement plans for the Sunbow II, Phase 3 project to identify
the sizing of all private water facilities for the project.
Water service to the project is proposed to be provided by making two connections to the
existing 624 Zone transmission line in Olympic Parkway. Each connection shall consist of a
12-inch public water main extension to serve one domestic service connection for the project
and one fire service connection for the project. An onsite private loop will be constructed for
domestic and fire protection systems from these connections. A master meter and backflow
preventer will be provided at each domestic connection and a backflow preventer will be
provided at each fire service connection.
The development pads on the project will range in elevation from approximately 370 feet to 420
feet. With service provided from the 624 Zone, this will result in maximum static pressures
ranging from 88 to 110 psi. Figure 4-1 provides the proposed potable and recycled water
systems for the project.
RECYCLED WATER
Recycled water is proposed to be used at all common landscaped areas within the project as
well as the irrigated areas of the private open space/CPF site. There is an existing 16-inch 680
Zone recycled water line in Olympic Parkway adjacent to the project. As shown on Figure 4-1,
a 6-inch public recycled water line is proposed in Street A and Street B and will make two
connections to the existing 16-inch public recycled water line in Olympic Parkway. Irrigation
meters will be connected to the proposed 6-inch public recycled water line and will be followed
by private irrigation piping to serve onsite irrigated areas. Service from the 680 Zone will
result in static pressures of 113 psi and 134 psi in the developed areas. Pressures at irrigated
slopes will vary from this and the landscape architect will verify the ability to serve all
irrigated areas of the project from the 680 Zone.
DEXTER WILSON ENGINEERING, INC. PAGE 4-1
There is an existing 30-inch 680 Zone recycled water line in the western part of the site.
Portions of this line will be relocated as a result of development activity. No connections are
proposed to this 30-inch line.
DEXTER WILSON ENGINEERING, INC. PAGE 4-2
APPENDIX A
LAND USE PROJECT DESCRIPTION