HomeMy WebLinkAboutDune Palms WQA
DUNE PALMS ROAD LOW WATER CROSSING REPLACEMENT
PROJECT
CITY OF LA QUINTA
RIVERSIDE COUNTY, CALIFORNIA
Water Quality Assessment Report
January 2016
Prepared for:
City of La Quinta
and
State of California Department of Transportation
Federal Project Number BRLKS-5433(014)
Prepared by:
01/16/15
Water Quality Assessment Report
Dune Palms Road Low Water Crossing Replacement Project
Federal Project Number BRLKS-5433(014)
January 2016
STATE OF CALIFORNIA
Department of Transportation
and
City of La Quinta
Prepared By: ___________________________________ Date: ____________
Brad Donais, PE, Project Manager
Heptagon Seven Consulting, Inc.
Approved By: Date: 1/16/15
Lorraine Ahlquist, Environmental Manager
Parsons Brinckerhoff
EXECUTIVE SUMMARY
The proposed project is located along Dune Palms Road over the Coachella Valley Storm Water
Channel (CVSC) between Highway 111 and Blackhawk Way/Westward Ho Drive in the City of La
Quinta, California. The proposed project will remove the existing low-water crossing of Dune
Palms Road at the CVSC in the City of La Quinta, Riverside County. The crossing will be replaced
with a 480 feet long and 86 feet wide four-span bridge. The bridge typical section consists of six-
foot sidewalk on both sides of the bridge, two (2) eight-foot outside shoulders also serving as
bike/golf cart lanes, a ten foot wide raised curb median, two (2) eleven-foot travel lanes, and two (2)
twelve-foot travel lanes.
The proposed configuration of Dune Palms Road within the project limits will be consistent with
the existing four-lane roadway section to the south, and the City’s current improvement project to
the north (City Project Number 2009-04), which will widen Dune Palms Road from two to four
lanes with a median and left turn lanes.
The proposed bridge project improvements will include a reconstruction of the north and south
bridge approaches to accommodate the significant raised profile of the roadway. In order to match
the roadway section on the south side of the bridge, the project’s construction limits will be
extended 239 feet south, ending north of Highway 111. On the north side of the bridge, the project
construction limits will be extended to include a vacant lot, immediately north of the project limits.
The vacant lot is owned by the City of La Quinta Housing Authority and will be offered by the
Authority in the bidding documents to be used for storage and construction staging by the contractor
for the construction of this project.
As a part of the bridge construction, concrete slope protection will be installed along the north side
of the channel. Additionally, minor removal and replacement of slope protection will be required
on the south side of channel west of the proposed bridge and extension of slope protection
approximately 300 feet downstream of the proposed bridge, which will accommodate a CVWD
requested maintenance ramp for access to the bottom of the channel. The slope protection is needed
for scour countermeasures. The use of the proposed cast-in-place drilled shaft bridge construction
for the bridge piers will eliminate the need to provide scour protection within the bottom of the
channel.
A construction Storm Water Pollution Prevention Plan (SWPPP) would be prepared by the
Contractor through the project specifications will identify the specific best management practices
(BMPs) to be implemented during project construction so as not to cause or contribute to an
exceedance of any water quality standard specified in the Colorado River Basin Water Quality
Control Plan (Basin Plan). These BMPs would be designed to meet the technology requirement as
stipulated in the Construction General Permit (CGP).
Compliance with the permit requirements of the National Pollutant Discharge Elimination System
(NPDES) permit No. CAS000003, the statewide General Construction Permit CA000002, RWQCB
Section 401 Water Quality Certification, Section 401 USACE Nationwide Permit and the City of La
Quinta standards would result in no adverse impacts to water quality with implementation of the
project.
Table of Contents
Introduction ................................................................................................................ 1-1
1.1 Purpose and Need .............................................................................................................. 1-1
1.1.1 Purpose ................................................................................................................ 1-1
1.1.2 Need .................................................................................................................... 1-1
1.2 Project Description............................................................................................................. 1-1
1.3 Approach to Water Quality Assessment ............................................................................ 1-4
Regulatory Setting ..................................................................................................... 2-1
2.1 Federal Laws and Requirements ........................................................................................ 2-1
2.1.1 Clean Water Act .................................................................................................. 2-1
2.1.2 Federal Flood Insurance Program ....................................................................... 2-2
2.1.3 Executive Order 11988 ....................................................................................... 2-2
2.2 State Laws and Requirements ............................................................................................ 2-2
2.2.1 The Porter-Cologne Water Quality Control Act ................................................. 2-2
2.3 Regional and Local Requirements ..................................................................................... 2-5
Affected Environment ............................................................................................... 3-1
3.1 General Setting................................................................................................................... 3-1
3.1.1 Land Use ............................................................................................................. 3-1
3.1.2 Topography/ Geology/Soil.................................................................................. 3-1
3.1.3 Precipitation and Climate .................................................................................... 3-3
3.1.4 Floodplains .......................................................................................................... 3-3
3.1.5 Municipal Supply ................................................................................................ 3-4
3.1.6 Biological Considerations ................................................................................... 3-4
3.2 Water Resource Setting...................................................................................................... 3-4
3.2.1 Regional Hydrology ............................................................................................ 3-4
3.2.2 Groundwater Resources ...................................................................................... 3-5
3.3 Water Quality Objectives/Standards and Beneficial Uses ................................................. 3-5
3.3.1 Surface Water Quality Objectives/Standards and Beneficial Uses ..................... 3-5
3.3.2 Groundwater Quality Objectives/Standards and Beneficial Uses ...................... 3-6
3.3.3 Possible Pollutants Affecting Water Quality ...................................................... 3-6
Environmental Consequences ................................................................................... 4-1
4.1 Impact Assessment Methodology ...................................................................................... 4-3
4.2 Short Term Impacts During Construction.......................................................................... 4-3
4.3 Permanent Impacts ............................................................................................................. 4-4
4.4 Cumulative Impacts ........................................................................................................... 4-6
Avoidance, Minimization, and Mitigation Measures.............................................. 5-1
References ................................................................................................................... 6-1
6.1 Work Cited ......................................................................................................................... 6-1
Preparers .................................................................................................................... 7-1
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Dune Palms Road Low-Water Crossing Replacement Project Jan. 2015
Table of Contents
List of Figures
Figure 1-1. Project Location Map ..................................................................................................... 1-3
Figure 1-2. Project Vicinity Map ...................................................................................................... 1-4
Figure 3-1. WWRSC and CVSC Map .............................................................................................. 3-2
List of Tables
Table 3-1. Possible Roadway Pollutants .......................................................................................... 3-7
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Introduction
This report was prepared for the replacement of the Dune Palms Road low water crossing at the
Coachella Valley Stormwater Channel (CVSC). The City of La Quinta is proposing to remove the
existing low water crossing of the CVSC and replace it with an all-weather bridge north of Highway
111 along Dune Palms Road. See Figure 1: Vicinity Map.
This report is intended to support the preparation of National Environmental Policy Act (NEPA)
and California Environmental Quality Act (CEQA) documentation for the project, which is funded
through the Federal HBP program. This report also supports efforts to obtain agreements, permits,
and concurrence needed to construct the proposed project.
1.1 Purpose and Need
1.1.1 Purpose
The purpose of the project is to replace the existing low-water crossing spanning the Coachella
Valley Storm Water Channel (CVSC) at Dune Palms Road with an all-weather access. The
proposed improvements will accomplish the following in the project area:
1. Provide safe access across the CVSC (Whitewater River) during all-weather events;
2. Provide reliable route for emergency vehicles, motorists, pedestrians, and bicyclists;
3. Achieve the City’s General Plan goals for the corridor.
1.1.2 Need
Dune Palms Road serves a vital access for emergency services within the project area, as well as for
La Quinta High, John Glen Middle and Amelia Earhart Elementary Schools. It also provides
connectivity of the city residential development north of the Channel with the Highway 111
commercial corridor located south of the CVSC. (See Figures 1-1 and 1-2).
The CVSC conveys storm water runoff from the surrounding mountains as well as developed areas
within the Coachella Valley. The elevation of the existing Dune Palms Road low-water crossing
causes it to flood during minor rain events (2-year frequency) and results in full street closure and
detour of both vehicle and pedestrian traffic. In the interest of public health and safety, and in
response to community concerns regarding frequent closures of the low-water crossing, the City of
La Quinta has determined that replacement of the low-water crossing with a new bridge is needed to
ensure that all-weather access is maintained. The Dune Palms Road low-water crossing is the last
remaining low-water crossing of the CVSC within the City.
1.2 Project Description
Existing Conditions. The existing roadway crosses the CVSC at the channel grade. The roadway
width is 68 feet at the crossing, and consists of one northbound and two southbound through lanes,
eight foot wide walkway area along the western edge, and an eight foot shoulder along the eastern
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1 | Introduction
edge of the road; and no median. The existing roadway approach south of the crossing consists of
one northbound and two southbound through lanes. The northern roadway approach consists of one
through lane in each direction. The transition from one to two lanes in the southbound direction
occurs at the midpoint of the channel crossing. Dune Palms Road approximately one-quarter mile
north of the channel low-water crossing and just south of the project limits is a four-lane roadway
with a median. The roadway section just north of the crossing will be widened as part of a prior
approved City project. The City Widening Project was originally approved with a Mitigated
Negative Declaration under CEQA in April 2010.
Proposed Improvements. The project proposes to remove the existing low-water crossing of Dune
Palms Road at the CVSC in the City of La Quinta, Riverside County. The crossing will be replaced
with a 480 feet long and 86 feet wide four-span bridge. The bridge typical section consists of six-
foot sidewalk on both sides of the bridge, two (2) eight-foot outside shoulders also serving as
bike/golf cart lanes, a ten foot wide raised curb median, two (2) eleven-foot travel lanes, and two (2)
twelve-foot travel lanes.
The proposed configuration will be consistent with the existing four-lane roadway section to the
south, and the City’s current improvement project to the north (City Project Number 2009-04),
which will widen Dune Palms Road from two to four lanes with a median and left turn lanes.
The proposed improvements will include a reconstruction of the north and south bridge approaches
to accommodate the significant raised profile of the roadway. In order to match the roadway section
on the south side of the bridge, the project’s construction limits will be extended approximately
240 feet south ending north of Highway 111. On the north side of the bridge, the project
construction limits and study area will extend along Dune Palms Road to include a vacant lot
immediately north of the project limits. The vacant lot is owned by the La Quinta Housing
Authority and will be offered by the Authority in the bidding documents to be used as a possible
storage and construction staging area by the contractor during the course of construction of this
project.
As a part of the bridge construction, concrete slope protection will be installed along the north side
of the channel. Additionally, minor removal and replacement of slope protection will be required
on the south side of channel west of the proposed bridge and extension of slope protection
approximately 300 feet downstream of the proposed bridge. The slope protection is required as a
scour countermeasure as a result of the construction of the bridge. Because of the proposed cast-in-
place drilled shaft bridge construction, scour protection within the bottom of the channel will not be
required.
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1 | Introduction
Figure 1-1. Project Location Map
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1 | Introduction
Figure 1-2. Project Vicinity Map
1.3 Approach to Water Quality Assessment
The purpose of the Water Quality Assessment Report (WQAR) is to fulfill the requirements of the
National Environmental Policy Act (NEPA) and the California Environmental Quality Act (CEQA),
and to provide information, to the extent possible, for National Pollution Discharge Elimination
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1 | Introduction
System (NPDES) permitting and to determine if the proposed project will have an adverse impact
on water quality. The document includes a discussion of the proposed project, the physical setting
of the project area, and the regulatory framework with respect to water quality. In addition, this
report provides data on surface water and groundwater resources within the project area and the
water quality of these waters, describes water quality impairments and beneficial uses, identifies
potential water quality impacts/benefits associated with the proposed project; and recommends
avoidance and/or minimization measures for potentially adverse impacts. The determination of
impacts is based on the anticipated change in pollutant loads due to changes in land use and in the
impervious area between the existing condition and the post project condition. The analysis includes
consideration of Best Management Practices (BMPs) to be implemented as part of the project.
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Regulatory Setting
2.1 Federal Laws and Requirements
2.1.1 Clean Water Act
In 1972, Congress amended the Federal Water Pollution Control Act, making the addition of
pollutants to the waters of the United States (U.S.) from any point source unlawful unless the
discharge complies with a NPDES permit. Known today as the Clean Water Act (CWA), Congress
has amended it several times. In the 1987 amendments, Congress directed dischargers of storm
water from municipal and industrial/construction point sources to comply with the NPDES permit
scheme. Important CWA sections are:
• Sections 303 and 304 require states to promulgate water quality standards, criteria, and
guidelines.
• Section 401 requires an application for a federal license or permit to conduct any activity, which
may result in a discharge to waters of the U.S., to obtain certification from the State that the
discharge will comply with other provisions of the act. (Most frequently required in tandem
with a Section 404 permit request. See below).
• Section 402 establishes the NPDES, a permitting system for the discharges (except for dredge or
fill material) of any pollutant into waters of the U.S. Regional Water Quality Control Boards
(RWQCB) administer this permitting program in California. Section 402(p) requires permits for
discharges of storm water from industrial/construction and Municipal Separate Storm Sewer
Systems (MS4s).
• Section 404 establishes a permit program for the discharge of dredge or fill material into waters
of the U.S. This permit program is administered by the U.S. Army Corps of Engineers
(USACE).
The objective of the CWA is “to restore and maintain the chemical, physical, and biological
integrity of the Nation’s waters.”
USACE issues two types of 404 permits: Standard and General Permits. For General permits, there
are two types: Regional permits and Nationwide permits. Regional permits are issued for a general
category of activities when they are similar in nature and cause minimal environmental effect.
Nationwide permits are issued to authorize a variety of minor project activities with no more than
minimal effects.
There are also two types of Standard permits: Individual permits and Letters of Permission.
Ordinarily, projects that do not meet the criteria for a Nationwide Permit may be permitted under
one of USACE’s Standard permits. For Standard permits, the USACE decision to approve is based
on compliance with U.S. Environmental Protection Agency’s (EPA) Section 404 (b)(1) Guidelines
(U.S. EPA CFR 40 Part 230), and whether permit approval is in the public interest. The 404(b)(1)
Guidelines were developed by the U.S. EPA in conjunction with USACE, and allow the discharge
of dredged or fill material into the aquatic system (waters of the U.S.) only if there is no practicable
alternative that would have less adverse effects. The Guidelines state that USACE may not issue a
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2 | Regulatory Setting
permit if there is a least environmentally damaging practicable alternative (LEDPA), to the
proposed discharge that would have less effect on waters of the U.S., and not have any other
significant adverse environmental consequences. Per Guidelines, documentation is needed that a
sequence of avoidance, minimization, and compensation measures have been followed, in that
order. The Guidelines also restrict permitting activities that violate water quality or toxic effluent
standards, jeopardize the continued existence of listed species, violate marine sanctuary protections,
or cause “significant degradation” to waters of the U.S. In addition, every permit from the USACE,
even if not subject to the 404(b)(1) Guidelines, must meet general requirements. See 33 CFR 320.4.
2.1.2 Federal Flood Insurance Program
Congress, alarmed by the increasing costs of disaster relief, passed the National Flood Insurance
Act of 1968 and the Flood Disaster Protection Act of 1973. The intent of these acts is to reduce the
need for large, public-funded flood control structures and disaster relief by restricting development
on the floodplain.
The Federal Emergency Management Agency (FEMA) administers the National Flood Insurance
Program (NFIP) to provide subsidized flood insurance to communities that comply with FEMA
regulations, which limit development in floodplains. FEMA issues Flood Insurance Rate Maps
(FIRMs) for communities participating in the NFIP. These maps delineate flood hazard zones in the
community.
2.1.3 Executive Order 11988
Executive Order 11988 (Floodplain Management) addresses floodplain issues related to public
safety, conservation, and economics. It generally requires federal agencies constructing, permitting,
or funding projects within floodplains to:
• Avoid incompatible floodplain development.
• Be consistent with the standards and criteria of the National Flood Insurance Program.
• Restore and preserve the natural and beneficial floodplain values.
2.2 State Laws and Requirements
2.2.1 The Porter-Cologne Water Quality Control Act
California’s Porter-Cologne Act, enacted in 1969, provides the legal basis for water quality
regulation within California. This Act requires a “Report of Waste Discharge” for any discharge of
waste (liquid, solid, or gaseous) to land or surface waters that may impair beneficial uses for surface
and/or groundwater of the State. It predates the CWA and regulates discharges to waters of the
State. Waters of the State include more than just waters of the U.S., like groundwater and surface
waters not considered waters of the U.S. Additionally, it prohibits discharges of “waste” as defined
and this definition is broader than the CWA definition of “pollutant”. Discharges under the Porter-
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2 | Regulatory Setting
Cologne Act are permitted by Waste Discharge Requirements (WDRs) and may be required even
when the discharge is already permitted or exempt under the CWA.
The State Water Resources Control Board (SWRCB) and RWQCBs are responsible for establishing
the water quality standards (objectives and beneficial uses) required by the CWA, and regulating
discharges to ensure compliance with the water quality standards. Details regarding water quality
standards in a project area are contained in the applicable RWQCB Basin Plan. In California,
Regional Boards designate beneficial uses for all water body segments in their jurisdictions, and
then set criteria necessary to protect these uses. Consequently, the water quality standards
developed for particular water segments are based on the designated use and vary depending on
such use. In addition, the SWRCB identifies waters failing to meet standards for specific pollutants,
which are then state-listed in accordance with CWA Section 303(d). If a state determines that
waters are impaired for one or more constituents and the standards cannot be met through point
source or non-source point controls (NPDES permits or Waste Discharge Requirements), the CWA
requires the establishment of Total Maximum Daily Loads (TMDLs). TMDLs specify allowable
pollutant loads from all sources (point, non-point, and natural) for a given watershed.
State Water Resources Control Board and Regional Water Quality Control Boards
The SWRCB adjudicates water rights, sets water pollution control policy, and issues water board
orders on matters of statewide application, and oversees water quality functions throughout the state
by approving Basin Plans, TMDLs, and NPDES permits. RWCQBs are responsible for protecting
beneficial uses of water resources within their regional jurisdiction using planning, permitting, and
enforcement authorities to meet this responsibility.
National Pollution Discharge Elimination System (NPDES) Program
Municipal Separate Storm Sewer Systems (MS4)
Section 402(p) of the CWA requires the issuance of NPDES permits for five categories of storm
water dischargers, including MS4s. The U.S. EPA defines an MS4 as “any conveyance or
system of conveyances (roads with drainage systems, municipal streets, catch basins, curbs,
gutters, ditches, human-made channels, and storm drains) owned or operated by a state, city,
town, county, or other public body having jurisdiction over storm water, that are designed or
used for collecting or conveying storm water.”
The Agency’s MS4 Permit, contains three basic requirements:
1. The Agency must comply with the requirements of the CGP (see below);
2. The Agency must implement a year-round program to effectively control storm water
and non-storm water discharges; and
3. The Agency storm water discharges must meet water quality standards through
implementation of permanent and temporary (construction) Best Management Practices
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2 | Regulatory Setting
(BMPs) to the Maximum Extent Practicable, and other measures as the SWRCB
determines to be necessary to meet the water quality standards.
Construction General Permit
Construction General Permit (Order No. 2009-009-DWQ, as amended by 2012-0006-
DWG), adopted on November 16, 2010, became effective on February 14, 2011. The permit
regulates storm water discharges from construction sites which result in a Disturbed Soil
Area (DSA) of one acre or greater. For all projects subject to the CGP, applicants are
required to develop and implement an effective Storm Water Pollution Prevention Plan
(SWPPP).
By law, all storm water discharges associated with construction activity where clearing,
grading, and excavation results in soil disturbance of at least one acre must comply with the
provisions of the CGP. Construction activity that results in soil disturbances of less than one
acre is subject to this CGP if there is potential for significant water quality impairment
resulting from the activity as determined by the RWQCB. Operators of regulated
construction sites are required to develop storm water pollution prevention plans; to
implement sediment, erosion, and pollution prevention control measures; and to obtain
coverage under the CGP.
The CGP separates projects into Risk Levels 1, 2, or 3. Risk levels are determined during
the planning and design phases, and are based on potential erosion and transport to receiving
waters. Requirements apply according to the Risk Level determined. For example, a Risk
Level 3 (highest risk) project would require compulsory storm water runoff pH and turbidity
monitoring, and pre- and post-construction aquatic biological assessments during specified
seasonal windows.
Section 401 Permitting
Under Section 401 of the CWA, any project requiring a federal license or permit that may
result in a discharge to a water of the United States must obtain a 401 Certification, which
certifies that the project will comply with State water quality standards. The most common
federal permit triggering 401 Certification is a CWA Section 404 permit, issued by USACE.
The 401 permit certifications are obtained from the appropriate RWQCB, dependent on the
project location, and are required before USACE issues a 404 permit.
In some cases, the RWQCB may have specific concerns with discharges associated with a
project. As a result, the RWQCB may issue a set of requirements known as Waste
Discharge Requirements (WDRs) under the State Water Code (Porter-Cologne Act) that
define activities, such as the inclusion of specific features, effluent limitations, monitoring,
and plan submittals that are to be implemented for protecting or benefiting water quality.
WDRs can be issued to address both permanent and temporary discharges of a project.
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2 | Regulatory Setting
2.3 Regional and Local Requirements
The Dune Palms low water replacement project is located within the Colorado River Basin Region
Water Quality Control Board (RWQCB Region 7). Within this region, the project specifically is
situated within the Salton Sea watershed.
Since this project will modify an existing and install additional storm drain outlets into the CVSC,
the project will be subject to the conditions of the RWQCB’s, Colorado River Basin Region,
Riverside County Flood Control and Water Conversation District (RCFCWCD) MS4 Permit, Order
No. R7-2013-0011, with the Coachella Valley Water District (CVWD) and City of La Quinta as co-
signees to the Permit. The proposed project design will comply with the requirements and measures
outlined in this municipal permit to minimize impacts to water quality and runoff hydrology for the
construction and operational phases of the proposed project.
The General Permit requires development and implantation of a Storm Water Pollution Prevention
Plan (SWPPP). The SWPPP must list Best Management Practices (BMPs) and enrollment under
the Stormwater Multiple Application and Report Tracking System (SMARTS).
The proposed project will also comply with the requirements and measures of the City of La
Quinta’s Ordinance No. 313, as amended by No. 470, and No. 493 revised in November 2011.
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Affected Environment
3.1 General Setting
The Whitewater River Basin is located approximately 100 miles east of Los Angeles. The
watershed drains to the Salton Sea located about 23 miles south of the project site. The tributary
area of the watershed is made up of a broad desert valley (Coachella Valley) between two
mountain ranges; the San Bernardino and Little San Bernardino Mountains form the northern
boundary of the watershed, and the San Jacinto and Santa Rosa Mountains form the western
boundary.
The Whitewater River Basin regional storm water conveyance system is comprised of the
Whitewater River Storm water Channel (WWRSC), which starts at the headwaters north of Palm
Springs and ends approximately 0.20 mile upstream from the Washington Street Bridge in La
Quinta, and the Coachella Valley Storm water Channel (CVSC), which starts downstream of the
WWRSC and discharges into the Salton Sea. The proposed Dune Palms Road Bridge is located
within the CVSC reach of the areas regional flood protection facility. (See Figure 3.1).
The drainage area tributary to the CVSC at the proposed Dune Palms Road Bridge is
approximately 788 sq. mi. (USCOE 1980)1. The mean seasonal precipitation in the area tributary
to the Dune Palms Road crossing varies from 44 inches at San Gorgonio Mountain to about 3
inches at the crossing.
3.1.1 Land Use
The Coachella Valley Storm Water Channel (CVSC) serves as flood protection to the surrounding
communities by intercepting and conveying regional flood flows to the Salton Sea. The land use
within the channel is limited to flood control protection with no parks, refuges, etc. located within the
channel boundaries. The area to the northwest of the channel crossing is the site of the La Quinta
High School, to the northeast is an existing mobile home park area, on the southeast is a vacant
commercial parcel and on the southwest is a built-out commercial office space complex. Within the
proposed project limits, the Coachella Valley Association of Governments (CVAG) is proposing to
construction a multi-modal (bicycle, pedestrian and low-speed electric vehicles) transportation
facility (CV Link ) along the WWRSC and CVSC. This facility will generally be located along the
southern top of the channel embankment, with benched under crossings at roadway bridge crossings
of the channel.
3.1.2 Topography/ Geology/Soil
The topography within the proposed project area is generally considered flat. In general, the
topography slopes from northwest to southeast within the project area.
1 Whitewater River Basin Feasibility Report for Flood Control and Allied Purposes, San Bernardino and Riverside
Counties, California. May 1980.
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3 | Affected Environment
Figure 3-1. WWRSC and CVSC Map
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3 | Affected Environment
According to the results of the geotechnical investigations prepared for the project, the project site
generally consists of the Southern California region is located on the boundary of two crustal or
tectonic plates: the Pacific plate and the North American plate.2 Movement along these two plate
boundaries causes seismic activity such as earthquakes as the Pacific plate slides past the North
American plate in what is termed a right-lateral transform or strike-slip motion. The surface
expression of this tectonic movement is expressed by the northwest-trending system of faults known
as the San Andreas fault system, which runs from north of the San Francisco area to the Bombay
Beach area of the Salton Sea and includes a Coachella Valley segment located northeast of the
project site.
Coachella Valley forms the northerly part of the Salton Trough (at the lowest point of which is the
Salton Sea) which is a structural and topographic depression that is related to complex interactions
within the San Andreas Fault system and is considered the northward extension of the Gulf of
California. Offsets along various detachment faults produced the Coachella Valley, which
progressively grew as the detachment faults moved. During this offset, sediments were dumped
from the topographic highs (mountains) to fill the lows (valleys) and developed geologic units in
such areas as the Indio and Mecca hills, which are now exposed.
Erosion of these elevated areas along with deposition from the Gulf of California and Colorado
River have provided as much as 12,000 feet of sediments in the basin. Soils of different ages and
compositions have developed on these sedimentary units, and on the younger alluvial units filling
the valley floor. Coachella Valley is underlain by a thick sequence of sedimentary deposits.
The Project site generally consists of alluvium to an explored depth of 120 feet below existing
grade. The alluvium at the site consists predominantly of spatially varying, interbedded layers of
fine sand (SP/SW) and silty fine sand (SM) with some gravel with little to no clay binder and silt
with fine sand and/or some clay. Thickness of these soil layers varies significantly, ranging from as
thin as one-foot or less to as thick as 15 to 20 feet or more.
3.1.3 Precipitation and Climate
The proposed project is located in Eastern Riverside County, the Coachella Valley, which is
considered an arid desert region averaging less than three inches of rain per year.
3.1.4 Floodplains
The CVSC along with the related tributary storm water facilities is the regional storm water
conveyance system for the Coachella Valley. FEMA provides information on flood hazards and
frequency on its FIRM’s for cities and counties, and identifies designated zones of flood hazard
potential. The proposed project site is within both FEMA flood zones “A” (area within the CVSC)
and “X” (areas north and south of the CVSC determined to be outside of the 100 and 500-year
floodplains), as defined by FEMA geographic information systems (GIS) data.
2 Bengal Engineering, Dune Palms Low Water Crossing Replacement. Preliminary Foundation Report. May 18, 2015.
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3 | Affected Environment
3.1.5 Municipal Supply
There are no drinking water reservoirs and/or recharge facilities within the project limits.
3.1.6 Biological Considerations
A Natural Environmental Study (NES) with a Jurisdictional Delineation (JD) was prepared for the
proposed project by ECORP Consulting, Inc., June 2015. The current Project is located within the
plan area for the Coachella Valley Multiple Species Habitat Conservation Plan (MSHCP). Both the
City and Caltrans are permittees and signatories to the MSHCP. According to the NES/JD, the
Biological Study Area (BSA) of the project is comprised of predominantly disturbed riparian
herbaceous area associated with CVSC. There are no intact, natural vegetation communities in the
BSA. However, there are several areas that support scattered native shrubs, including rubber
rabbitbush, creosote (Larrea tridentata), and fourwing saltbush (Atriplex canescens). Within the
BSA, the CVSC was determined to be a potential jurisdictional Waters of the U.S. as set forth in 33
CFR 328.33(a). The channel is characterized as having an earthen bottom and sides, thus supporting
vegetation growth. The water flow is intermittent and the CVSC conveys surface storm water runoff
during significant rain events. There was also a potential jurisdictional wetland area consisted of a
freshwater marsh found to the west of Dune Palms Road associated with a pipe outlet conveying
urban runoff. Due to its small extent, no substantial native aquatic resources are expected to use this
marsh habitat. Aquatic plants and animals do not occur within the remainder of the river channel.
During reconnaissance surveys, sensitive wildlife species and rare plant species were not detected
within the BSA. There is no critical habitat located within the BSA.
The CVSC is a hospitable corridor for local wildlife movement. Currently, wildlife that cross Dune
Palms Road are at risk from moving vehicles and other pedestrian activities residing on the low
water crossing.
3.2 Water Resource Setting
The following sections describe the water resources at the regional level and the resources that
occur with the Environmental Study Limits.
3.2.1 Regional Hydrology
The Whitewater River is the major drainage course within the Coachella Valley. There is perennial
flow in the mountains, but because of diversions and percolation into the basin, the River becomes
dry further downstream. The constructed downstream extension of the River channel known as the
Coachella Valley Storm Water Channel, serves as a drainage way for irrigation return flows, treated
community wastewater, and storm runoff.
Average annual precipitation ranges from less than three inches in the valleys to 40 inches in the
San Bernardino Mountains. Seasonal snows fall on the higher elevations in the San Bernardino and
San Jacinto Mountains. In the valleys, precipitation from summer thunderstorms often exceeds that
of winter.
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3 | Affected Environment
Runoff resulting from rains and snowmelt at the higher elevations is the major source of ground
water replenishment. Perennial streams include the upper reaches of the San Gorgonio and
Whitewater Rivers, and Palm Canyon, Tahquitz, Snow, Deep Canyon, Chino, and Andreas Creeks.
3.2.2 Groundwater Resources
Ground water within the proposed project area is stored principally in the unconsolidated
Pleistocene sediments. Wells yield up to 4,000 gpm. Maximum thickness of the water-bearing
sediments is not known; however, it exceeds 1,000 feet in Coachella Valley.
Ground water is generally unconfined except in the lower areas of the Coachella Valley. A clay
aquitard, a result of past sedimentation in the old lakebed, extends from the Salton Sea to some
distance west of Indio, overlying the domestic-use aquifers. The clay layer underlies lenses of
permeable sediments and perched ground waters, which are replenished by percolating irrigation
water.
The Coachella Valley is faulted extensively, altering ground water movement. The Mission Creek,
Banning, and San Andreas Faults form effective barriers to ground water movement. The Indio
Hills, Garnet Hills, and Mecca Faults form partial barriers.
The Indio and Mecca Hills have been uplifted along the northwest-trending San Andreas Fault
system. The alignment of oases on the flanks of those hills results from faults that impede the
movement of ground water. The most prominent of these oases is the Thousand Palms Oasis on the
Mission Creek Fault.
The quality of the groundwater within the region meets both the State Water Resources Control
Board Division of Drinking Water (DDW) and the US Environmental Protection Agency (USEP)
drinking water quality standards.
3.3 Water Quality Objectives/Standards and Beneficial Uses
The proposed project footprint intersects the upper reach of the CVSC. The Whitewater River
Region Stormwater Management Plan (SWMP), revised January 2015, describes those activities
and programs implemented by the Permittees to manage Urban Runoff to comply with the
requirements of the National Pollutant Discharge Elimination System (NPDES) municipal separate
storm sewer system (MS4) permit for the Whitewater River Region. Within the project location of
the CVSC, the surface water quality has been incrementally improving through the installation of
improvements to the storm drain systems outletting into the CVSC, using of BMP’s on removal of
trash debris and reduction of nuisance waters.
3.3.1 Surface Water Quality Objectives/Standards and Beneficial Uses
The proposed project footprint intersects the upper reach of the CVSC, and according to the most
recent CWA Section 303(d) list, this segment does not show any impairments. The CVSC closer to
the Salton Sea does list 303(d) impairments of DDT, Dieldrin, PCB’s (Polychlorinated biphenyls),
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3 | Affected Environment
Pathogens and Toxaphene.3 Furthermore, the location of the proposed project is outside of the
documented limits of beneficial uses and any quantitative surface water quality objectives for the
CVSC.
Starting approximately 7 miles downstream of the project limits along the CVSC, the RWQCB
documents the following Beneficial Uses and their Basin Plan designations for water bodies:
Coachella Valley Storm Water Channel (CVSC) from Indio to the Salton Sea
• FRSH; Freshwater Replenishment
• RECI (Unauthorized use); Water Contact Recreation
• RECII (Unauthorized use); Non-Contact Water Recreation
• WARM; Warm Freshwater Habitat
• WILD; Wildlife Habitat
• RARE; Preservation of Rare, Threatened or Endangered Species
Salton Sea
• AQUA; Aquaculture
• IND (Potential use); Industrial Service Supply
• RECI; Water Contact Recreation
• RECII; Non-Contact Water Recreation
• WARM; Warm Freshwater Habitat
• WILD; Wildlife Habitat
• RARE; Preservation of Rare, Threatened or Endangered Species
For the reach of the CVSC from Indio to the Salton Sea, the E. Coli quality objective for RECI is
126 MPN per 100 ml and RECII is 630 MPN per 100 ml. The water quality objective for the
Salton Sea is to reduce the present level of salinity and stabilize it at 35,000 mg/l. However, due to
economic and political considerations, 35,000 mg/l is not realistically achievable without
fundamental changes to the configuration and/or composition of the inflow water.
3.3.2 Groundwater Quality Objectives/Standards and Beneficial Uses
The proposed project site is entirely underlain by the Coachella Valley Groundwater Basin. The
beneficial uses of the basin include municipal supply, agricultural supply, industrial service supply
and industrial process supply. All groundwaters are subject to the water quality objectives
described in the Coachella Valley Water Management Plan Update, dated January 2012.
3.3.3 Possible Pollutants Affecting Water Quality
The U.S Department of Transportation completed a study in 1996 to identify possible pollutants that
may be impacted by water quality from roadways. The following table (Table 3-1) contains a list of
pollutants known to contribute to water quality related issues and are sourced to roadways.
3 State Water Resources Control Board. Clean Water Act, Section 303(d) List of Water Quality Limited Segments. 2010.
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Table 3-1. Possible Roadway Pollutants
Constituents Primary Sources
Particulates Pavement wear, vehicles, atmosphere, maintenance, sediment disturbance
Lead Auto exhaust, tire wear, lubricating oil and grease, bearing wear, atmospheric fallout
Zinc Tire wear, motor oil, grease
Iron Auto body rust, steel highway structures, moving engine parts
Copper Metal plating, bearing & bushing wear, moving engine parts, brake lining wear,
fungicide & insecticide application
Cadmium Tire wear, insecticide application
Chromium Metal plating, moving engine parts, brake lining wear
Nickel Diesel fuel and gasoline, lubricating oil, metal plating, bushing wear, brake lining
wear, asphalt paving
Manganese Moving engine parts
Bromide Exhaust
Sodium, Calcium Grease
Sulphate Roadway bed and fuel
Petroleum Spills, leaks or blow-by of motor lubricants, antifreeze and hydraulic fluids, asphalt
PCBs, Pesticides Spraying of highway rights-of-way, atmospheric deposition, PCB catalyst in
synthetic
Pathogenic Bacteria Soil litter, bird droppings, trucks hauling livestock/stockyard waste
Rubber Tire wear
Asbestos* Clutch and brake lining wear
Source: U.S. Department of Transportation. Federal Highway Administration. Publication No.
FHWA-PD-96-032. June 1996.
Note: * No mineral asbestos has been identified in runoff; however, some breakdown products of
asbestos have been measured.
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Environmental Consequences
The proposed project would include pipes, swales, and changes to the roadway profile grade. The
flow would be directed to both existing and new storm water drainage systems that outlet into the
CVSC. Localized scour as a result of the storm drain outlets would be mitigated through the
installation of a concrete outlet structure integrated into the concrete slope protection. There are no
off-site drainage areas that contribute to the runoff that would be generated by this project.
The existing project footprint has an impervious area of 2.06 acres. The proposed project will have
an impervious area of 2.06 acres. The proposed project impervious area accounts for the additional
street pavement width, excluding the area of the proposed bridge decking, and the proposed
concrete slope protection along the northwest and southeast channel slopes. Therefore, the project
will have no net increase or decrease in impervious area within the project corridor. Nonetheless,
the project will evaluate city approved treatment BMP’s to the maximum extent possible (MEP) per
the requirements of the NPDES permit (No. CAS000003).
The primary concern within this reach of the CVSC is the outletting of nuisance water into the
channel. In an effort to address nuisance flows, the project will utilize drywells to intercept
nuisance water prior to outletting into the channel. The drywells would be installed in combination
with the last manhole and or catch basin prior to channel outlet. The drywells would also address
containment and treatment of the first flush water from rain events, thus collecting debris and sand
prior to the storm drain outlet.
The major project elements will consist of the construction of a bridge 480-foot long bridge,
modifications to the roadway approach width and profile to match the proposed bridge structure,
concrete slope protection along the northwest and southeast corners of the crossing and the
localized storm drain systems to address the low points created by the revised roadway profile. In
addition, due to encroachments into the existing street right of way, up to three residential structures
(one single family residence and two mobile homes) will be removed as a part of the project.
The following sections present an analysis of potential water quality impacts anticipated from the
proposed project activities, and BMPs that will be implemented to avoid and minimize impacts that
the project may have on water quality. Several pollutants are commonly associated with storm water
runoff, including sediment, nutrients, bacteria and viruses, organic compounds, trash and debris,
oxygen-demanding substances, oil and grease, toxic pollutants such as pesticides, and metals. These
pollutants are described in more detail below.
Sediment
Natural sediment loads are important to downstream environments because they provide habitat,
substrate, and nutrition; however, increased sediment loads can result in negative effects to
downstream environments. Excessive sediment can be detrimental to aquatic life by interfering with
photosynthesis, respiration, growth, and reproduction. In addition, pollutants that adhere to
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4 | Environmental Consequences
sediment such as nutrients, trace metals, and hydrocarbons can have other harmful effects on the
aquatic environment when they occur in elevated levels.
Nutrients
Nutrients are typically composed of phosphorus and/or nitrogen. Elevated levels in surface waters
cause algal blooms and excessive vegetative growth. As nutrients are absorbed, the vegetative
growths decompose, utilizing oxygen in the process and reducing dissolved oxygen levels.
Dissolved oxygen is critical for support of aquatic life. The ammonium form of nitrogen (found in
wastewater discharges) converts to nitrite and nitrate in the presence of oxygen, which further
reduces the dissolved oxygen levels in water.
Bacteria and Viruses
Bacterial levels in urban runoff can exceed public health standards for water contact recreation,
creating a harmful environment. The source is animal or human fecal wastes. Bacteria and viruses
thrive under certain conditions and can alter the aquatic habitat and create a harmful environment
for aquatic life.
Organic Compounds
Organic compounds are carbon-based and are found in pesticides, solvents, and hydrocarbons.
Elevated levels can indirectly or directly constitute a hazard to life or health. During cleaning
activities, these compounds can be washed off into storm drains. Dirt, grease, and grime may adsorb
concentrations that are harmful or hazardous to aquatic life.
Oxygen-Demanding Substances
Oxygen-demanding substances include plant debris (such as leaves and lawn clippings), animal
wastes, and other organic matter. Microorganisms utilize dissolved oxygen during consumption of
these substances, which reduces a water body’s capacity to support aquatic life.
Trash and Debris
Trash and debris can have a significant effect on the recreational value of a water body and aquatic
habitat. It also can interfere with aquatic life respiration and can be harmful or hazardous to aquatic
animals that mistakenly ingest floating debris.
Oil and Grease
Primary sources of oil and grease are petroleum hydrocarbon products, motor products from leaking
vehicles, fats, and waxes. Elevated oil and grease concentrations can affect the aesthetic value of the
water body and can create a harmful environment for aquatic life and species that use the Upper
Newport Bay for foraging and nesting.
Pesticides
A pesticide is a chemical agent designed to control pest organisms. Pesticides can persist in the
environment and can bioaccumulate (concentrate within the body) over several years, resulting in
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4 | Environmental Consequences
health problems for the affected organism. Pesticides have been repeatedly detected in surface
waters and precipitation.
Metals
Bioavailable forms of trace metals are toxic to aquatic life. The most common metals found in
urban runoff are lead, zinc, and copper. Sources of heavy metals in surface waters include emissions
and deposits from automobiles, industrial wastewater, and common household chemicals. At high
concentrations, metals are toxic to aquatic life. Humans can be impacted from contaminated
groundwater resources and from bioaccumulation of metals in fish and shellfish.
4.1 Impact Assessment Methodology
The impact analysis evaluates the differences between the existing condition and the project build
conditions with respect to impervious area and relation to amount of runoff (increase or decrease),
and application of BMPs (number of BMPs, new technologies, effectiveness). Since the project
will be constructing a bridge and approach roadway section to the ultimate street section noted in
the City’s General Plan, the items addressed under the Permanent Impacts section include the
conditions immediately following construction as well as for the 10 and 20-year horizon. The
vacant parcel located at the southeast corner of the proposed channel crossing will be required to
address on-site storm water and surface water quality.
4.2 Short Term Impacts During Construction
No Build Alternative. Under the No Build Alternative, no roadway improvements other than
routine roadway maintenance would be made to the Dune Palms Road low water crossing. The
Coachella Valley Water District (CVWD) is responsible for all maintenance operations within the
channel area. Therefore, this alternative would result in no short-term water quality impacts
resulting from construction-related activities.
Build Alternative. The full construction project will disturb up to 9.4 acres of land within the right
of way of Dune Palms Road and within the channel banks of the CVSC. Pollutants of concern
during construction include sediments, trash, petroleum products, and chemicals. Each of these
pollutants on its own or in combination with other pollutants can have a detrimental effect on
surface water quality, aquatic habitats, and groundwater quality. During the construction activities,
excavated soil would be exposed, and there would be an increased potential for soil erosion
compared to existing conditions. Additionally, during a storm event, soils would be exposed to
potential mobilization by rainfall/runoff; therefore, soil erosion and sediment releases could occur at
an accelerated rate.
Under the General Permit, the project is required to implement erosion control, sediment control,
non-storm water management, run-on and runoff controls, and good site management housekeeping
practices. Construction BMPs and their applicable uses approved by the SWRCB are provided in
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4 | Environmental Consequences
the California Stormwater Handbook, Construction. In addition, the City is required to minimize or
prevent pollutants in storm water discharges and authorized non-storm water discharges through the
use of controls, structures, and management practices that achieve best available technology
economically achievable (BAT) for toxic and nonconventional pollutants and Best Conventional
Pollutant Control Technology (BCT) for conventional pollutants.
4.3 Permanent Impacts
No Build Alternative. The existing roadway facility directs storm and nuisance waters directly into
the channel via the existing gutter and storm drain system. This storm drain system and/or outlet
does not have any facilities to remove trash, debris and sediment prior to entering the CVSC.
Furthermore, the existing storm drainage system does not address nuisance water flows nor first
flush flows. Therefore, this alternative would not result in an increase in long-term pollutant
loading, however, existing runoff would remain untreated.
Build Alternative. As noted above, the proposed project has a zero net change in impervious
surface. Furthermore, the project will provide BMP measures to address both nuisance waters and
sediment collection from the first flush flows. The project intends on installing and retrofitting the
existing storm drainage systems with drywell’s which will address the nuisance water and sediment
collection prior to storm water outletting into the CVSC. The existing storm drain outlets and all
new outlets will consists of the pipe outlet surrounded by a concrete headwall and sidewalls to
minimize erosion. In addition, those areas where slope protection is currently not present within the
construction limits, the project will be placing concrete slope lining to protect the bridge from the
effects of scour and other facilities including existing and or new storm drain outlets. With the
inclusion of the above noted BMP’s in addition to the net decrease in impervious area, the project is
not anticipated to have any adverse impacts on the beneficial uses and hydrology of the receiving
waters.
The north roadway has an existing City storm drain system and outlet along the west side of Dune
Palms Road. This storm drain outlet will be retrofitted into the proposed concrete slope protection
through the integration of a concrete outlet structure. Additionally, due to the change in the
roadway approach profile to accommodate the proposed bridge structure, the project design will
require the placement of a low point to the north of the bridge. At this low point, the project will
require the installation of catch basins on both sides of the street to collect storm water. This
localized storm drain system will be tied into the existing storm drain system. Furthermore, the
existing storm drain system will be retrofitted with a drywell to address nuisance and first flush
water. This existing storm drain outlet has an existing permanent encroachment permit with
CVWD, whom is responsible for the operations and maintenance channel. Because of the outlet
modifications, CVWD will require a permit amendment to the existing permanent encroachment
permit for this outlet.
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4 | Environmental Consequences
The south roadway approach currently drains directly into the CVSC. As noted above, the project
will require the installation of a local storm drain system to convey street drainage into the CVSC.
Due to the new storm drain outlet into the CVSC, the City will need to obtain a permanent
encroachment permit from CVWD. This permit will address the construction, operations and
maintenance activities that will be required by the City to perform as a result of this outlet.
The proposed limits of the project are as follows:
• 530 feet south of the CVSC along Dune Palms Road;
• 330 feet north of the CVSC along Dune Palms Road;
• 330 feet west of the centerline of Dune Palms Road along the CVSC; and
• 400 feet east of the centerline of Dune Palms Road along the CVSC.
Based on preliminary engineering for the Project, there would be 0.05 acre and 12 linear feet of
temporary impacts and 0.02 acre and 5 linear feet of permanent impacts to United State Army Corps
of Engineers (USACE) and California Department of Fish and Wildlife (CDFW) jurisdictional areas.
The freshwater marsh located on site is considered a riparian habitat type, although it is dominated
by disturbed plant species and is of low habitat value. There were no sensitive wildlife species nor
rare plant species detected within the project area. There is no critical habitat located within the project
area including jurisdictional waters. The receiving waters characteristics will be protected with the
implementation of construction and design BMPs. Therefore, it is not anticipated that the project will
have any adverse impact on any biological resources. Although the project activities will temporarily
affect corridor functionality for wildlife movement, the planned bridge will improve the corridor by
creating a safe undercrossing for mobilizing wildlife. Prior to the beginning of construction activities,
the following approvals/ permits will be obtained or determined not applicable by the City through
additional coordination with the applicable Federal and State resource agencies:
• Streambed Alteration Agreement pursuant to California Fish and Game Code Section 1602;
• USACE Nationwide Permit pursuant to CWA Section 404; and
• RWQCB 401 Water Quality Certification pursuant to CWA Section 401.
Through complying with the City’s NPDES permit (NPDES No. CAS617002), the above noted 1602,
404 and 410 permits, and implementing of minimization measures to the maximum extent practical,
designing and operating the project’s facility would not be expected to cause adverse impacts to water
quality to any of the receiving waters. It is anticipated that the mitigation measures noted above will
cost approximately $80,000. Per the Whitewater River Storm Water Management Plan (SWMP), the
MS4 permittees are required to implement the SWMP. The SWMP describes various Best
Management Practices (BMPs) that are to be implemented by the Permittees in order to control
stormwater pollution to the Maximum Extent Practicable (MEP). Included in the implementation of
the SWMP is agency submittal of an Annual Report. Within this reach of the CVSC, the City of La
Quinta has maintenance responsibility for the storm drain system and outlet, while CVWD has
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4 | Environmental Consequences
maintenance of the channel area. Both of the maintenance responsibilities include the regular
inspection and maintaining of the facilities under each agencies control to the provisions of the
NPDES permit.
4.4 Cumulative Impacts
The Coachella Valley Storm Water Channel (CVSC), which operates as the major flood control
facility for entire Coachella Valley, has a number of anticipated near future projects that may affect
the flood way over the next ten years. However, all projects associated with the channel and
specifically work required within the channel right of way are subject to the local, state and Federal
water quality rules and regulations and the improvements would be developed in compliance with
the regulations in a manner that avoids negative impacts to the water resource. Furthermore,
CVWD, who is responsible for the operations and maintenance of the CVSC, requires all projects
affecting the CVSC obtain a construction encroachment permit, which involves review and
approval of the plans to ensure applicable state and Federal water quality rules and regulations have
been implemented for each specific project.
Based on the above provided information, this project will not negatively impact receiving waters in
the project area, and will not have cumulative impacts on the water resource characteristics or
beneficial uses.
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Avoidance, Minimization, and Mitigation
Measures
Consistent with NPDES permit requirements as well as with selected Construction, Pollution
Prevention, and Treatment BMPs will be incorporated into the final design and construction of the
proposed project. These BMPs will reduce pollutant loading in runoff from the existing roadway
approaches to the channel (which currently is not treated) during construction as well as the
proposed roadway. Therefore, compliance with the listed measures will result in no potential for
adverse short-term and long-term impacts to water quality.
WQ-1 The City of La Quinta (City) will comply with the provisions of the National Pollutant
Discharge Elimination System (NPDES) General Permit for Storm Water Discharge from
Construction and Land Disturbance Activities as they relate to construction activities for the
project (NPDES No. CAS617002). This will include submission of the Permit Registration
Documents, including a Notice of Intent (NOI), site map, Storm Water Pollution Prevention
Plan (SWPPP), annual fee, and signed certification statement to the State Water Resources
Control Board (SWRCB) at least 14 days prior to the start of construction. The SWPPP will
meet the requirements of the Construction General Permit (No. CA000002) and will identify
potential pollutant sources associated with construction activities; identify non-storm water
discharges; and identify, implement, and maintain Best Management Practices (BMPs) to
reduce or eliminate pollutants associated with the construction site. A Notice of
Termination (NOT) will be submitted to the SWRCB upon completion of construction and
stabilization of the site.
WQ-2 The proposed project will install a two chambered drywell system to all existing and
proposed drainage system outletting into the CVSC to address nuisance water flows as well
as to capture sediment from the initial first flush flows from storm events.
WQ-3 Stormwater BMPs strategies will be coordinated with RWQCB, and will comply with 401
permit requirements.
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References
6.1 Work Cited
The following references and links may help with gathering information for WQAR:
Bengal Engineering, Dune Palms Low Water Crossing Replacement. Preliminary Foundation
Report. May 18, 2015.
California Department of Transportation. Storm Water Quality Handbook, Project Planning and
Design Guide. July 2010.
California Department of Water Resources. California’s Groundwater: Bulletin 118. February 27,
2004.
California Stormwater Quality Association. Stormwater Best Management Practice (BMP)
Handbook, Construction. January 2003.
Colorado River Basin Regional Water Quality Control Board. Water Quality Control Plan,
Colorado Basin, adopted June 2006.
Colorado River Basin Watershed Management Initiative Strategic Planning Chapter, October 2004.
Flood Insurance Rate Map No. 06065C2234G, August 28, 2008.
Parsons Brinckerhoff, Dune Palms Road Low Water Crossing Replacement Project. Natural
Environment Study, including Jurisdictional Waters Delineation, July 2015.
State Water Resources Control Board. National Pollutant Discharge Elimination System (NPDES)
Permit Statewide Storm Water Permit and Waste Discharge Requirements (WDRs) for
Municipal Separate Storm Sewer Systems within the Whitewater River Watershed (Renewal),
Order No. R7-2013-0011, NPDES No. CAS617002.
State Water Resources Control Board. Clean Water Act, Section 303(d) List of Water Quality
Limited Segments. 2010.
U.S. Army Corps of Engineers. Whitewater River Basin Feasibility Report for Flood Control and
Allied Purposes, San Bernardino and Riverside Counties, California. May 1980.
Whitewater River Region. Stormwater Management Plan. June 2014, revised January 2015.
Whitewater River Region. Water Quality Management Plan Guidance Document. June 2014,
revised January 2015.
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Preparers
Ron Moreno, PE, PLS, QSP/QSD, Project Engineer, BS Civil Engineering, 20 years of experience,
prepared the Water Quality Assessment
Brad Donais, PE, Project Manager, BS Civil Engineer, 22 years of experience, reviewed and revised
the Water Quality Assessment
Lorraine Ahlquist, AICP, Environmental Manager, BS Environmental Studies, MS Biological
Sciences, 22 years of experience, oversaw the preparation and final review of the Water
Quality Assessment Report
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