Background: The County of Stanislaus (County) circulated an Initial Study/Negative Declaration (IS/ND) for the West Modesto Sewer Infrastructure Project (Project) from May 4, 2018 to June 4, 2018. Since that time, a modification to the proposed Project has been identified as being necessary to revise the Project description. This Addendum is provided as a supplement to the environmental analysis provided in the Final IS/ND, pursuant to State California Environmental Quality Act (CEQA) Guidelines Section 15164. The Addendum was circulated to the State Office of Planning and Research from August 2, 2021 to September 1, 2021. A Notice of Availability was also published in the Modesto Bee on August 2, 2021, advertising the proposed Addendum and a public comment period from August 2, 2021 to September 1, 2021.
The Project involves the installation of sanitary sewer mains and laterals in three separate unincorporated neighborhoods within Modesto, CA. The 2018 Final IS/ND included analysis of the proposed sewer infrastructure project, but did not assess potential effects of the connection from private properties into the public sewer laterals. Initially, the connection from private properties to the public sewer system was not part of the infrastructure project and was anticipated to occur at later dates with private property owners incurring the associated costs. Since the completion of the IS/ND, the County commenced procuring funds from the California State Water Resources Control Board (SWRCB) to allow private property owners to abandon their septic tanks and connect to the existing City of Modesto’s public sewer system.
Revised Project Description: The County, in cooperation with HUD and SWRCB, propose to install sanitary sewer mains and laterals, with private property connections to each residence, in three separate unincorporated neighborhoods within West Modesto in Stanislaus County, California (see attachments: Figure 1: project Vicinity Map, Figure 2: Project Location Map, and Figure 3, Revised Area of Potential Effects Map). It is estimated that the Project will include the installation of up to 80,000 linear feet of gravity mains and approximately 1,004 new house laterals in the Spencer/Marshall (144 services), Beverly/Waverly (527 services), and Rouse/Colorado (333 services) neighborhoods. The Spencer/Marshall neighborhood is generally located approximately 0.3 mile west of Highway 99 and is accessible from State Route 132 and Spencer Avenue. The Beverly/Waverly neighborhood is located approximately 0.9 mile west of Highway 99 and is accessible from Paradise Road. The Rouse/Colorado neighborhood is located approximately 0.6 mile west of Highway 99 and is accessible from Tuolumne Boulevard and Roselawn Avenue. The following street intersections and road segment are part of the Project site: the California/Marshall Avenue intersection; the Paradise Road/Pine Tree intersection; and approximately 100’ east of the Lombardy Drive/Ritsch Lane intersection.
The Spencer/Marshall, Beverly/Waverly, and Rouse/Colorado neighborhoods are disadvantaged communities located in West Modesto with predominantly residential parcels that currently rely on septic tanks for the treatment of sewage. The Project is proposed in response to health and safety concerns associated with failing septic systems which could lead to the degradation of groundwater quality. The Project will include the installation of a new sewer system with approximately 80,000 linear feet of sewer main and street reconstruction. The completed Project will allow property owners to abandon their existing septic tanks and connect to a public sewer system with private property connections paid for by State Water Board grant funding awarded to the County and installed through individual construction contracts approved by the County. The new sewer infrastructure will connect into the City of Modesto’s existing public sewer system. Upon completion of the Project, ownership of the public sanitary sewer improvements will be transferred to the City of Modesto for operation and maintenance.
Existing private septic systems and water services will remain active during Project construction. No road closures are anticipated to occur and access to each residence will be maintained. Minor temporary detours for local traffic may take place. Temporary construction easements, utility easements, and encroachment permits may be needed on a limited basis to accommodate the installation of the proposed improvements. Construction of the public sanitary sewer improvements for the Spencer/Marshall area is anticipated to last six months, for the Beverly/Waverly area eighteen months, and for the Rouse/Colorado area twelve months. Private sewer connections from individual properties to the public sewer laterals are expected to be completed within two years of the City’s acceptance of the public sewer improvements.
The City of Modesto’s (City) River Trunk Realignment project is co-located in the Colorado Avenue street segment of Project Area 9. The City’s project will include construction of gravity pipelines, force mains, and two new pump stations. Construction of the public sanitary sewer improvements for the Rouse/Colorado Project (Area 9) will be completed concurrently with the City’s project. The City prepared a Wastewater Master Plan Final Environmental Impact Report (FEIR) in October of 2019 which included the River Trunk Realignment project. The City’s project impacts were reviewed and were not found to affect the County’s sewer Project.
The Project will be constructed using local, SWRCB, and Community Development Block Grant funds; therefore, coordination with the HUD under NEPA will be required and the County is the lead agency for CEQA purposes and the responsible entity for NEPA purposes.