SUBJECT
Title
AUTHORIZATION TO ADVERTISE AND AWARD A CONSTRUCTION CONTRACT FOR SUNSET AVENUE RETAINING WALL PROJECT AND RELATED CEQA DOCUMENT (DISTRICT: 4)
Body
OVERVIEW
The County of San Diego’s (County) Department of Public Works (DPW) maintains nearly 2,000 centerline miles of roads in unincorporated San Diego County. Centerline miles represent the total length of the roads regardless of the number of lanes or the overall roadway width. County roads traverse a variety of regions and conditions, from two-lane roads in mountainous terrain to multi-lane roads in dense population centers. All County-maintained roads are regularly evaluated for safety measures to protect the public. Typical safety measures include traffic signals, roadway signage, and guardrails; but on occasion, other more specialized safety measures, such as retaining walls and similar structures are required to prevent erosion and slope failure.
Sunset Avenue is a County maintained road located in unincorporated La Mesa along Mt. Helix. The location of the improvements along Sunset Avenue are on a section of one-way roadway between the intersections of Fuerte Drive and Summit Circle for a distance of about 0.17-miles. The proposed project will construct a retaining wall to support the roadway in place of the existing foundation constructed from stacked, unreinforced rock structure. The existing foundation is subject to erosion and seismic failure. The proposed improvements will construct a retaining structure known as a soldier pile wall. Soldier pile walls are predominantly used where there is a sudden change in elevation, such as steep embankments to prevent the lateral movement of soil and will provide a strong foundation for the roadway.
The repair work will be to remove and replace about 100 linear feet of the existing roadway to allow the installation of soldier piles and associated lagging panels. The roadway will be resurfaced, an asphalt curb will be installed along the edge of the road to control storm water runoff and a chain link fence will be installed for the length of the repair to replace the existing failed fence. During construction, Sunset Ave will be closed along the one-way section of roadway and traffic will be detoured to Summit Drive, a roadway that parallels Sunset Avenue to the south. The detour is anticipated to add an additional .07 miles to the trip or about an addition 45 seconds. Adjacent residence will be able to access their homes and driveways during construction. These improvements will ensure that the roadway will be safe for local residence and the traveling public.
This is a request to approve the advertisement and subsequent construction contract award to the lowest responsive and responsible bidder for the Sunset Avenue Retaining Wall Project. If approved, construction costs are estimated to be $600,000, including contingencies, for a total cost of $750,000. Construction will begin in spring 2025 and is anticipated to be complete in summer 2025.
RECOMMENDATION(S)
CHIEF ADMINISTRATIVE OFFICER
1. Find in accordance with Section 15301 of the California Environmental Quality Act (CEQA) Guidelines that the proposed project is categorically exempt from CEQA review because it involves the maintenance and repair of existing facilities involving no or negligible expansion of existing use. Find in accordance with Section 15304 of CEQA Guidelines that the proposed project is categorically exempt from CEQA review because it consists of minor alterations to public land without removal of mature trees.
2. Authorize the Director, Department of Purchasing and Contracting, to take any action necessary to advertise and award a contract and to take other actions authorized by Section 401 et seq., of the Administrative Code with respect to contracting for curbs, gutters, and sidewalks, throughout the unincorporated region of the County.
3. Designate the Director, Department of Public Works, as the County Officer responsible for administering the construction contract in accordance with Board Policy F-41, Public Works Construction Projects.
EQUITY IMPACT STATEMENT
The County of San Diego strives to preserve, enhance, and promote quality of life and environmental resources through the implementation of projects that improve road facilities. Rehabilitation of retaining walls offers several equity benefits, including enhanced safety and preserved infrastructure. A functional retaining wall prevents soil erosion and protects properties from damage. Retaining walls often support sidewalks, roads, or other infrastructure. Rehabilitation safeguards these structures, preventing costly repairs and ensuring they remain accessible to all. County of San Diego construction contracts are also competitively and publicly advertised and bid and help stimulate the local economy.
SUSTAINABILITY IMPACT STATEMENT
The repair work for the Sunset Ave Retaining Wall will have economic and environmental sustainability benefits. Upkeep of existing infrastructure prevents more costly future maintenance efforts, thereby reducing environmental impact and supporting economic sustainability. The retaining wall repair work proposed in this action will utilize fewer resources compared to demolishing the wall and rebuilding it entirely. This translates to conversing raw materials and minimizing construction waste which contributes to San Diego County’s sustainability goal of reducing pollution and waste.
FISCAL IMPACT
Funds for this request are included in the Fiscal Year 2024-25 Operational Plan in the Department of Public Works Road Fund Detailed Work Program. If approved, the construction costs are estimated at $600,000, including a 20% contingency for unforeseen conditions. The total estimated project costs are $970,109. The funding source is available prior year Road Fund fund balance. There will be no change in net General Fund cost and no additional staff years.
BUSINESS IMPACT STATEMENT
County of San Diego construction contracts are competitively and publicly bid and help stimulate the local economy by creating construction-related employment opportunities. All workers employed on Public Works projects must be paid the prevailing wages determined by the Department of Industrial Relations, according to the type of work and location of the project. The prevailing wage rates are usually based on rates specified in collective bargaining agreements. A skilled and trained workforce requirement will be included in the contract in compliance with the County’s Working Families Ordinance requirements for County construction projects.
Details
ADVISORY BOARD STATEMENT
The Valle De Oro Community Sponsor Group (CSG) has been notified that the San Diego County Board of Supervisors is considering this request today and the group is appreciative of the proposed repairs. The CSG has requested to continue to be updated on the construction timeline. Department of Public Works staff also met on-site with property owners adjacent to the project and provided them with a point of contact for any questions they may have regarding design and construction of the retaining wall. The adjacent property owners are agreeable to the construction and road closure based on the conversations that the Department of Public Works personnel had with them during recent conversations.
BACKGROUND
The Department of Public Works (DPW) maintains nearly 2,000 centerline miles roads in unincorporated San Diego County. Centerline miles represent the total length of the roads regardless of the number of lanes or the overall roadway with. County roads traverse a variety of regions and conditions, from two-lane roads in mountainous terrain to multi-lane roads in dense population centers. All County-maintained roads are regularly evaluated for safety measures to protect the public. Typical safety measures include traffic signals, roadway signage, and guardrails; but on occasion, other more specialized safety measures, such as and retaining walls and similar structures are required to prevent erosion and slope failure.
Sunset Avenue is a County maintained road located in unincorporated La Mesa along Mt. Helix. The location of the improvements along Sunset Avenue are on a section of a one-way roadway between the intersections of Fuerte Drive and Summit Circle for a distance of about 0.17-miles. The proposed project will construct a retaining wall to support the roadway in place of the existing foundation constructed from stacked, unreinforced rock structure. The existing foundation is subject to erosion and seismic failure. The proposed improvements will construct a retaining structure known as a soldier pile wall. Soldier pile walls are predominantly used where there is a sudden change in elevation, such as steep embankments to prevent the lateral movement of soil and will provide a strong foundation for the roadway.
A Preliminary Engineering Report (PER) was completed to analyze possible solutions to reconstruct the existing foundation constructed from stacked, unreinforced rock structure, which is subject to erosion and seismic failure. The PER compared the costs and constructability between three wall types:
1. Standard concrete wall on a continuous spread footing: A continuous spread footing on a wide strip of concrete that supports the weight of the wall and distributers it evenly across the soil.
2. Soldier pile wall on deep pile foundations: Vertical steel piles driven into the ground at intervals, with horizontal lagging placed between them to hold back the soil.
3. Keystone wall: Built with interlocking concrete blocks to create a strong and stable wall.
The PER recommended option two, the soldier pile wall on deep pile foundations, as the preferred alternative because it required the least impact to the existing roadway and the least construction time, as well as serving the most cost-effective option. The standard concrete wall and keystone wall required the whole roadway section to be removed and rebuilt and cost were about 20% higher than the soldier pile wall.
The repair work will be to remove and replace about 100 linear feet of the existing roadway to allow the installation of soldier piles and associated lagging panels. The roadway will be resurfaced, an asphalt curb will be installed along the edge of the road to control storm water runoff and a chain link fence will be installed for the length of the repair to replace the existing failed fence. During construction Sunset Ave will be closed along the one-way section of roadway and traffic will be detoured to Summit Drive, a roadway that parallels Sunset Avenue to the south. The detour is anticipated to add an additional .07 miles to the trip or about an additional 45 seconds. Adjacent residence will be able to access their homes and driveways during construction. These improvements will ensure that the roadway will be safe for local residence and the traveling public.
Prior to the start of construction, notifications will be sent to property owners and surrounding residences in advance, including mailers and doorknob-type notices. All work will be within the existing public right of way. County staff will be onsite throughout the duration of the Project and will be available to respond to any project related inquiries from the public.
This is a request to approve the advertisement and subsequent construction contract award to the lowest responsive and responsible bidder for the Sunset Avenue Retaining Wall Project. If approved, construction costs are estimated to be $600,000, including contingencies, for a total cost of $750,000. Construction will begin in spring 2025 and is anticipated to be complete in summer 2025.
ENVIRONMENTAL STATEMENT
Section 15301 of the CEQA Guidelines exempts from CEQA review activities related to operation, repair, maintenance, or minor alteration of existing facilities. The key consideration in applying this exemption is whether the project involves negligible or no expansion of existing use. Also, Section 15304 of the CEQA Guidelines exempts from CEQA review activities consisting of minor public alterations in the condition of land, water, and/or vegetation, with the key consideration involving preservation of healthy, mature, or scenic trees. The proposed project involves repair and reconstruction of an existing failed retaining wall within the County’s right-of-way located on Sunset Avenue in La Mesa, CA. The project also includes road resurfacing of a segment of Sunset Avenue adjacent to the retaining wall. The project is categorically exempt in accordance with Sections 15301 and 15304 of the CEQA Guidelines because it involves minor alteration of existing public facilities, with no expansion of existing or former use, and involves minor alteration of public land without removal of mature trees. Therefore, the project is categorically exempt from CEQA review in accordance with Sections 15301 and 15304 of the CEQA Guidelines.
LINKAGE TO THE COUNTY OF SAN DIEGO STRATEGIC PLAN
Today’s recommendations support the Sustainability, Community, and Equity Strategic Initiatives in the County of San Diego’s 2024-2029 Strategic Plan by providing funding for infrastructure that strengthens the local economy and providing improvements to ensure safe and livable communities for all residents.
Respectfully submitted,
AMY HARBERT
Interim Deputy Chief Administrative Officer
ATTACHMENT(S)
A - Vicinity Map