Boston — The American Public Works Association (APWA) named the South Essex Sewerage District's Marblehead Pipeline Replacement Project as one of its Public Works Projects of the Year for 2016. The award was presented on August 29 during the APWA’s Public Works Expo in Minneapolis.
The APWA Public Works Project of the Year Award was established to promote excellence in the management and administration of public works projects by recognizing the alliance between the managing agency, the consultant/architect/engineer, and the contractor.
The project, which was recognized in the category of environmental projects of $5 million to $25 million, was designed by WSP | Parsons Brinckerhoff on behalf of the District. The contractor was Caldwell Marine International.
The project was initiated by the District after a leak was discovered in a section of one of the twin underwater pipelines which carried all sewage from the Town of Marblehead some 6,000 feet across Salem Harbor to the District’s wastewater treatment facility in Salem. In cooperation with federal, state and local agencies, the District immediately implemented a response plan.
A condition assessment performed by WSP | Parsons Brinckerhoff identified severe corrosion of the existing pipelines. The assessment, which examined the existing 20-inch and 24-inch ductile iron pressure sewers, included direct underwater observations of the pipelines, ultrasonic thickness tests and sediment corrosivity analyses, all of which indicated that the pipes needed to be replaced to prevent the potential leakage of sewage into Salem Harbor.
The discovery of deteriorated pipe at locations along several thousand feet of subaqueous pipeline made planning and execution of the replacement urgent, because imminent failure could have occurred at any time. WSP | Parsons Brinckerhoff recommended that the pipelines be replaced using non-corroding high-density polyethylene pipe, installed by direct burial in a new trench adjacent to the existing pipes, and connecting to the existing valve structures at both ends of the pipelines.
Environmental mitigation for the pipeline construction was extensive and carefully detailed in the contract documents. The design team and the District worked closely with federal, state and local permitting agencies to ensure the project was constructed in a manner that protected the surrounding environment, recreational resource areas and shipping activity. WSP | Parsons Brinckerhoff also provided assistance to the District in its successful application for funding under the State Revolving Loan Fund.
Replacing the pipeline proved to be a complex process. Since sanitary service could not be interrupted, the existing pipelines had to remain in service until the new pipes were ready to receive flow, and no work could take place near the existing pipes until a temporary bypass connection was established, using one of the new permanent pipes. In addition to contending with boating and recreational activities, working in the historic harbor presented special challenges. For example, marine construction activities were limited from mid-April to the end of June to minimize adverse impacts on flounder spawning. Stringent silt controls and turbidity monitoring also were required.
Despite difficult winter conditions, the project reached substantial completion by August 2015. The deteriorating pipeline was replaced with a state-of-the-art pipeline that is expected to serve the community well for the 21st Century.