San Anselmo contractor uncovers significant inflow issues during sewer lateral investigation

The Ross Valley Sanitary District meeting held on March 19, 2025, focused on significant infrastructure issues, particularly concerning the investigation of unknown sewer laterals in the San Anselmo area. The discussions highlighted the challenges faced by contractors in identifying and verifying these laterals, which often appeared to be live connections despite not being documented in existing plans.

The meeting began with a detailed report on the ongoing investigations along Austin Avenue and Ross in Sunnyside, where numerous unaccounted connections were discovered. Contractors utilized video inspections to identify these connections, leading to the need for excavation to determine their status. Many of these laterals were found to be sources of inflow and infiltration, contributing to excess water flow in the system.

The conversation then shifted to change orders related to the project. Change order number four detailed the findings from the investigations, while change order number five provided a final accounting of the project, including adjustments for discrepancies in footage and costs. The contractor's camera system required recalibration, necessitating a re-measurement of footage, which was verified by third-party inspectors.

Additionally, the meeting addressed the substantial costs associated with hot mix asphalt used throughout the project. The need for additional paving work was discussed, particularly in areas where pipes were in poor condition. The contractor's proactive identification of defects in adjacent areas allowed for timely repairs, which were completed before a vocal homeowner returned from vacation.

Overall, the meeting underscored the complexities of managing sewer infrastructure in the region, with a focus on addressing previously unknown issues that could impact the efficiency of the sanitary system. The discussions concluded with an acknowledgment of the importance of thorough inspections and timely interventions to maintain the integrity of the sewer network.