The City of Lawrence, MA faces substantial infrastructure challenges, but through a robust sewer system evaluation and rehabilitation and a comprehensive illicit discharge detection and elimination program, the City is taking significant steps to improve the quality of the environment along the Merrimack River corridor and to protect the drinking water source for the community.
Like many other cities in the region, Lawrence has many miles of combined sewers within the wastewater collection system that serves its more than 75,000 residents. Because of the city’s location on the Merrimack River, which is also its drinking water source, Lawrence has extra incentive to improve the performance of its sewers and drains, reduce or eliminate combined sewer overflows, reduce its flow contribution to the Lawrence Sanitary District (GLSD) Wastewater Treatment Facility, and extend the life of its infrastructure. Lawrence and Woodard & Curran have worked together to implement a multi-phased Sanitary Sewer Evaluation Survey (SSES), followed by extensive sewer rehabilitation work and a proactive illicit discharge detection and elimination (IDDE) program.
IDDE PROGRAM IMPROVES WATER QUALITY
Facing a federal Consent Decree, Lawrence undertook a more comprehensive IDDE program than what is typical for a community of its size. The City has a high potential for direct illicit discharges in areas where combined sewers were converted to separate sanitary sewer and stormwater systems, so the IDDE program focuses on the detection of direct illicit discharges into the City’s MS4. Woodard & Curran has helped the City assess and prioritize investigation areas, sample and screen stormwater outfalls, confirm and remove illicit connections, and put prevention, follow-up, and training systems in place. With these projects, the City has made great strides to achieve water quality goals and protect public health.
SSES AND CMOM DRIVES SEWER REHAB EFFORT
Knowing the City had aging infrastructure problems, Woodard & Curran and Lawrence performed a comprehensive Capacity, Management, Operations and Maintenance (CMOM) study to identify and prioritize the areas with the greatest consequence of failure. CMOM findings prioritized future phases of SSES fieldwork that identified structural and maintenance-related defects within the pipelines that present a “material risk of failure.” Using a combination of techniques including flow isolation, CCTV, manhole inspections, building inspections, rainfall simulations, and smoke testing, priority areas for rehabilitation were identified. Ongoing maintenance and capital repairs were planned and implemented to address broken pipes, leaking joints, obstructions, sump pumps, roof leaders, driveway drains, leaking manholes, defective inverts, and other illegal connections. Together, these projects identify problem areas before they become emergencies, significantly reduced I/I and will help Lawrence achieve its goal or reducing sanitary and wet weather flows and protecting its vital water resources.