As the Town of Plymouth focuses on the inspection and cleaning of its aging infrastructure, and expanding their systems to meet the needs of their growing community, the existing sewer collection system was identified as an area needing attention. The current system is aging with over 40% of the system estimated to be more than 50 years old.
To address this concern and plan and implement upgrades, Environmental Partners (EP) was brought on board to assist the Town with their Capacity, Management, Operation, and Maintenance (CMOM) program in response to an administrative consent order with the US EPA.
The CMOM program is focused on improving understanding of the sewer collection system’s structural and maintenance condition so as to identify potential risks, prioritize repair and rehabilitation projects to the most critical assets, and develop a long-term Collection System Maintenance Plan for routine inspection and cleaning. The Town of Plymouth’s sewer system is extensive, including approximately 285,000 feet of gravity sewer and 1,550 sewer manholes, so implementing a CMOM program required a phased approach to systematically provide for the inspection and cleaning of the system. The CMOM program is being completed in 2 phases. Phase 1 encompassed data collection for the sewer collection system over a planned three year period beginning in the downtown Plymouth Harbor area in Fiscal Year 2016 before expanding to the eastern and western areas of the Town’s sewer collection system in Fiscal Year 2017 and 2018. Phase 2 encompasses the review and analysis of all Phase 1 baseline conditions to develop the Town’s long-term Collection System Maintenance Plan.
Phase 1 focuses on establishing the baseline conditions that will be used to develop the Town’s Collection System Maintenance Plan. Utilizing existing Town GIS information and previous Corrective Action Plans created by the Town, EP developed construction documents for each year of work. EP solicited quotes from various sewer cleaning companies and contracted the work to the most qualified company, and coordinated daily cleaning and CCTV work between the Contractor and the Town, updated the Town’s sewer GIS database based on findings, and prepared a final report for EPA to document the Town’s compliance with the administrative consent order. In Year 1 approximately 80,000 linear feet of gravity sewer and 502 sewer manholes were inspected and cleaned. In Year 2 approximately 100,000 linear feet of gravity sewer and 445 manholes were inspected and cleaned. In Year 3 approximately 75,000 linear feet of gravity sewer and 400 manholes were inspected and cleaned. Adding complexity to the situation, the first year of the program also had to be coordinated with the emergency response actions undertaken after the 2015 failure of the Town’s 30-inch sewer force main. Phase 1 of the CMOM program is currently continuing towards meeting its inspection goal as documented in the administrative consent order.
Phase 2 will take place over two years and is currently in progress, beginning in Fiscal Year 2019 and ending in Fiscal Year 2020. The goal of Phase 2 is to utilize all of the baseline information obtained during Phase 1 and develop the Town’s Collection System Maintenance Plan, which will include routine and preventative maintenance plans for all elements of the collection system, public education and outreach, and capital improvement planning.