ASHLAND, Maine — The Ashland Water and Sewer District recently completed a project that rid its three wastewater treatment lagoons of 55 years of sludge.
In February, district superintendent Frank Martin reported that the utility would do its first-ever full sludge removal, a process recommended every 20 years but which the town hadn’t done since the lagoons were built in 1963.
The district received two grants totaling $1.9 million for the work, a Community Development Block Grant (CDBG) and a DEP Clean Water State Revolving Fund (CWSRF) grant. The project went to public bidding nationwide in December 2017, and Merrell Brothers, a biosolids management corporation from Kokomo, Indiana, won the contract this spring.
Ashland’s lagoons “were in urgent need of cleaning to stay in compliance with state and federal regulations,” said Merrell Brothers via a press release. After 55 years of operation, the lagoons were experiencing a rapid growth of algae that promoted an increase of solid sludge, which could potentially become an environmental and public hazard.
Martin said in the press release he was impressed by the company’s work. “Their team and heavy dredge equipment arrived at the work site on June 9, and the entire process was completed on July 16, more than two weeks ahead of schedule,” he stated. “They didn’t play around. Their workers were very focused and meticulous. They did a great job for us.”
“The cleaning process is quite intriguing,” said project consultant Brayden Merrell in the company’s statement. “It begins on the surface of the lagoon, where a hydraulic dredge pumps a thick slurry of sludge from the bottom of the lagoon floor to a mixing tank, where the slurry is kept consistent and thoroughly mixed.
“Equipped with individual pumps, each filter belt press machine draws sludge and cationic emulsion polymer onto the machine’s top deck. Mixed with sludge, the polymer acts as a binding agent, locking onto solid molecules while repelling liquid molecules,” he said.
“The material begins to coagulate and proceeds through a series of rollers that provide pressure on the material. This allows for solids to be captured and conveyed directly to roll off boxes or semi-trucks (which take the material to be properly disposed), all while returning clean water directly back to the lagoon.”
Martin noted the town learned a great deal from the project and are now in the process of completing additional restorations at the bottom of the lagoons.
