HomeMy WebLinkAboutDume Palms VIADune Palms Road Low-Water Crossing Replacement Project 1
M e m o r a n d u m
To: Sean Yeung, Acting Office Chief Date: March 24, 2015
Planning and Local Assistance
464 West 4th Street, 6th floor, MS 760 File No.: 08-Riv-Local Assistance
San Bernardino, CA 92401-1400
Dune Palms Road Low-Water
Crossing Replacement Project
FPN: BLRKS-5433 (014)
From: Edward J. Wimmer, P.E.
Principal Engineer
City of La Quinta
760-777-7088
Subject: Scenic Resource Evaluation and Visual Impact Assessment
The City of La Quinta is proposing to replace the existing low-water crossing spanning the Coachella
Valley Storm Water Channel (CVSWC) at Dune Palms Road with an all weather access bridge (Figure 1).
Dune Palms Road serves a vital north/south link for emergency services, as well as for the La Quinta
High, John Glenn Middle and Amelia Earhart Elementary Schools. It also provides connectivity to the
Highway 111 commercial corridor for residential development north of the channel.
The CVSWC 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 proposed project would replace the existing roadway with a 480-foot long by 86-foot wide four-
span bridge. The bridge typical-section would consist of six-foot sidewalk on both sides of the bridge,
two eight-foot outside shoulders (also serving as bike/golf cart lanes), a raised median, two 11-foot
travel lanes, and two 12-foot travel lanes. The proposed bridge would have an increased roadway width
as compared to the existing roadway in order to accommodate the raised median; however, the
proposed configuration would be compatible with the existing four-lane roadway section to the south,
and the City’s current roadway improvement project to the north. In order to meet the Coachella Valley
Water District hydraulic requirements, the bridge would have a significant vertical grade raise. The
existing roadway approaches would be reconstructed to accommodate the raised profile effectively
extending the project’s construction limits to Highway 111 south of the project and to a vacant lot north
of the project (Figure 2). The vacant lot is owned by the City and may be used for storage and
construction staging.
Scenic Resource Evaluation and Visual Impact Assessment
Dune Palms Road Low-Water Crossing Replacement Project 2
Dune Palms Road is designated as a secondary arterial in the City’s General Plan with an ultimate right-
of-way profile of 102 feet with six-foot sidewalks and seven-foot setbacks. The roadway is not identified
as an image corridor; however, Highway 111 does have an image corridor designation by the City. Image
corridors provide views of the surrounding community as well as horizon views of the Coachella Valley
area and Santa Rosa Mountains. They are considered a community asset and have special consideration
and protection. The project’s construction limits would extend to the north of Highway 111. Uses within
the project area include vacant land, commercial buildings, La Quinta High School, a single-family
residence, and a mobile-home park (Photos 1, 2, 3 & 4). Views from the roadway consist of adjacent
development, open views along the channel of the surrounding area, and horizon views of the
mountains (Photos 5 & 6). Those who have views of the project site are motorists and pedestrians using
the facility, homeowners who have views oriented to the roadway, and commercial users, owners, and
employees accessing the commercial areas from the roadway. Homeowners and pedestrians are
considered to be highly-sensitive to visual change as they experience the visual environment on a
personal level. Motorists and commercial users are considered to be moderately-sensitive to visual
change as their priority is on their task, with the visual environment being second or third in priority to
their primary task. The project is considered to be an improvement to how the roadway currently
functions and therefore is anticipated to be viewed favorably by those who use it, as well as live and/or
work near it. Therefore, viewer sensitivity is considered moderate to low with viewer expectation
reducing viewer sensitivity.
The project would require right-of-way acquisition on the northeast and southeast corners of the
proposed bridge. The northeast corner is developed with one single-family home and a mobile home
park area all within the same parcel (Photo 7). The southeast corner is vacant (Photo 8). Currently, many
of the existing mobile homes along the frontage of Dune Palms Road and encroaching into the existing
street right of way. The project’s proposed right-of-way requires only partial use of the parcel upon
which the residence and mobile homes are located. Pending approval by the property owners of partial
property acquisition and access modification, the project will be designed to avoid impacts by relocating
the mobile homes within the same area of the park if possible. Other options include relocation within
other vacant lots in the same park or nearby parks.
As a part of the bridge construction, concrete slope protection would be installed along the north side of
the channel. The upstream section of the slope protection would join the existing slope protection
approximately 190 feet west of the proposed bridge. Likewise, minor removal and replacement of slope
protection would be required on the south side of the channel, west of the proposed bridge, and
extension of slope protection approximately 300 feet downstream of the proposed bridge. Based on
current design, scour protection within the channel bottom is not anticipated. Additionally, the
Coachella Valley Association of Governments and the communities within the Coachella Valley are
working together on the implementation of Project for a regional Bike/Pedestrian/NEV corridor (CV Link)
along Whitewater River and CVSWC. In accordance with this plan, the project would be designed to
allow for the integration of a trail under-crossing within the southern slope protection. The project
would also include a trail connector to the pedestrian and bike facilities along Dune Palms Road. Dune
Palms is identified for Class III Bicycle Paths (shared facilities) in the City’s General Plan.
Scenic Resource Evaluation and Visual Impact Assessment
Dune Palms Road Low-Water Crossing Replacement Project 3
During construction, the existing roadway would be modified to incorporate a temporary bypass which
will allow for staged construction of the bridge, and to maintain vehicle and pedestrian access at all
times. Temporary and short term access impacts may occur and would require coordination with
property owners, the public, and other stakeholders.
The proposed bridge would not obstruct views and in some instances may open up new views within the
segment that would be raised above the channel bottom. The project will require limited acquisitions of
right-of-way. The proposed acquisitions would not change the overall character or quality of views
within the affected area. The proposed bridge would not be out of character with surrounding uses and
would fit within the overall context of the existing roadway and regional bike/pedestrian/NEV corridor.
To enhance the visual character of the bridge, the design would incorporate the standard La Quinta
architectural treatment for the railing to achieve the community design goals. Viewers most affected by
the proposed project are expected to be pedestrians as they experience the visual environment on a
more personal level. The visual character of the at-grade portion of the roadway is expected to change
slightly from a somewhat rural to semi-urban feel as the bridge structure would have a modern, hard-
surface character offering expanded views from an elevated versus at-grade perspective. This change is
not expected to be viewed negatively by pedestrians and in some cases may be a welcome change as
safety would be improved and views would be expanded. Views for motorists and pedestrians would
change to include horizon and corridor views of the mountains and surrounding areas primarily along
the elevated segment of the roadway. Views of the roadway from adjacent residences and commercial
areas are limited and represent the minority of available views to these viewer groups. The elevated
bridge is not expected to affect views for these users or be viewed negatively. The proposed bridge
would not affect the character or visual quality of Highway 111 or the elements of its character and
quality that classify it as an image corridor.
The proposed project would not change the overall character or visual quality of the project corridor or
surrounding areas. The project is not expected to be viewed negatively by viewer groups. It would not
affect designated scenic resources, Section 4(f) or 6(f) properties, or historic sites, properties or districts.
The proposed project would be consistent with the visual character desired by the community and is not
expected to be controversial. Although the project would result in physical changes to the roadway and
portions of the channel, it would not affect views or visual quality within the project area. The project
would not result in substantial adverse visual impacts and would be consistent with local plans and
policies.
Dune Palms Road Low-Water Crossing Replacement Project 4
Figure 1: Vicinity Map
Scenic Resource Evaluation and Visual Impact Assessment
Dune Palms Road Low-Water Crossing Replacement Project 5
Figure 2: Site Map
Scenic Resource Evaluation and Visual Impact Assessment
Dune Palms Road Low-Water Crossing Replacement Project 6
Figure 3: Photo Location Map
Scenic Resource Evaluation and Visual Impact Assessment
Dune Palms Road Low-Water Crossing Replacement Project 7
Photo 1: Vacant land southeast of Dune Palms Road Photo 2: Commercial buildings southwest of Dune Palms Road
Photo 3: La Quinta High School northwest of Dune Palms Road Photo 4: Single-family home and mobile-home park northeast of
Dune Palms Road
Scenic Resource Evaluation and Visual Impact Assessment
Dune Palms Road Low-Water Crossing Replacement Project 8
Photo 5: Dune Palms Road looking west along the channel Photo 6: Dune Palms Road looking south
Photo 7: Single-family residence and mobile-home park northeast
of Dune Palms Road and the channel
Photo 8: Vacant lot southeast of Dune Palms Road and the
channel