Joint Water Pollution Control Plant Effluent Outfall Tunnel Western Avenue Boring

The Joint Water Pollution Control Plant Effluent Outfall Tunnel Western Avenue Boring project, managed by the Los Angeles County Sanitation Districts, involves emergency boring and drilling operations along Western Avenue in Los Angeles, specifically approximately 600 feet south of Weymouth Place. The scope of work requires the execution of up to fourteen exploratory boreholes reaching depths of up to 365 feet below the ground surface to investigate a partial tunnel breach that occurred on July 9, 2025. Because CalOSHA has prohibited direct access into the breached tunnel, these drilling efforts are the only viable method to assess the tunnel's condition and investigate a potential void to prevent further settlement of the surrounding area. Upon completion of the drilling campaign, all boreholes must be abandoned in strict accordance with Los Angeles County and California Well Standards. The project is classified as an emergency repair to a public service facility essential to public health and safety, granting it an exemption under CEQA guidelines. Administrative oversight is provided by the Planning Section of the County Sanitation Districts of Los Angeles County, with Patricia Horsley serving as the primary environmental planner and point of contact.