Project History
Decades of Combined Sewer Challenges
Like many older cities, Lowell’s sewer system was originally built as a combined system, carrying both sewage and stormwater in the same pipes. During heavy rain, the capacity of this combined system can be exceeded, resulting in a Combined Sewer Overflow (CSO), which is a discharge of untreated wastewater and stormwater directly into local waterways, including the Merrimack River.
Federal Clean Water Act Requirements
The Clean Water Act (CWA) of 1986 required that municipalities nationwide take steps to reduce or eliminate combined sewer overflow (CSO) discharges to receiving streams to improve water quality. In response, the United States Environmental Protection Agency (USEPA) issued a series of interim CSO control policies and adopted a final National CSO Control Policy in 1994. This Policy established a comprehensive national strategy to ensure that municipalities, permitting authorities, water quality standards authorities, and the public engage in a coordinated planning effort to develop and implement cost-effective CSO controls that meet appropriate environmental and health objectives. Massachusetts adopted its own version of this CSO policy in 1997.
In 1988, the City of Lowell entered into a Consent Decree with the USEPA and MassDEP, requiring a long-term strategy to reduce CSOs. Subsequently, Lowell developed several planning documents and construction projects to prioritize and implement cost-effective sewer separation projects across the city. Since the implementation of the consent decree to 2024, Lowell has invested over $150 million in CSO projects that have reduced the annual volume of overflows from the Lowell system and drastically reduced street flooding. The City is currently 40% combined by area.
Why Do CSO's Exist in the First Place?
Many older cities like Lowell were built with combined sewer systems. A Combined Sewer Overflow (CSO) occurs when heavy rain or snowmelt overwhelms the sewer system, causing untreated wastewater and stormwater to discharge directly into rivers or other water bodies. CSOs are a key cause of water pollution in older cities with combined sewer systems.
Renewed Focus During 2022–2023 Consent Decree Negotiations
As part of a Lowell’s new Consent Decree (a legally binding agreement, between Lowell and environmental regulatory agencies (MassDEP & EPA, that outlines specific actions and timelines for improving a wastewater system) that was finalized in 2024, the City of Lowell is committed to moving forward with sewer separation in the Centralville neighborhood.
2023 Preliminary Design Report
The initial report outlined separation concepts for the Centralville area, supported by hydraulic modeling, field investigations, and community input. Multiple outfall options were considered due to complex constraints like flood protection levees, utility conflicts, and topography. The 2023 Preliminary Design Report (2023 PDR) was submitted to the agencies in December 2023 for approval.
Based on feedback from MassDEP and EPA, the 2023 PDR was revised to further address the technical and permitting challenges of separating this area and present a phased implementation schedule based on cost, community, and construction considerations. The revised plan was positively received and forms the basis of the current Centralville Sewer Separation Project.
Modernizing Infrastructure for a Resilient Centralville.
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Contact
- 451 First Street Boulevard Lowell, MA 01850
- sewer@lowellma.gov
- (978) 674-4248