Совет Мэрримака одобрил закупку на 250 тысяч долларов для обеспечения безопасности очистных сооружений после ухода пивоварни Anheuser-Busch

The departure of Anheuser-Busch from a large industrial plot in Merrimack is prompting changes to the way the town’s public works department handles wastewater. While the brewing giant was around, staff at Merrimack’s wastewater treatment facility didn’t have to worry about adding chemicals to maintain the correct effluent pH. Because Anheuser-Busch used magnesium hydroxide in quantities so large, the residual effect kept the plant’s pH within the required range to maintain its National Pollutant Discharge Elimination System permit. During a meeting of Merrimack’s Town Council on Aug. 20, DPW staff asked councilors to consider approving $250,000 in capital improvement fund spending to purchase and install a sodium hydroxide storage tank, and other related equipment, to be used to maintain acceptable effluent pH at the wastewater treatment plant. “Our NPDES permit requires us to maintain a pH between 6.5 to 8, this protects aquatic life such as fish and the environment,” Assistant Public Works Director Leo Gaudette said. “The Merrimack River is already considered impaired for pH.” A new dry feeder unit will be able to hold several weeks’ worth of material. The nitrification process, which Merrimack uses at its facility, converts ammonia to nitrogen gas, which naturally suppresses the pH. Ammonia can be toxic to fish and other aquatic life. Nitrification also removes phosphorus, which is a requirement of the NPDES permit. “Anheuser-Busch used to provide a significant alkalinity and pH adjustment due to their magnesium hydroxide use in their process,” he said. “We now have to add sodium bicarbonate and sodium hydroxide to maintain our effluent pH to meet our NPDES permit, because AB is now gone.” Since September 2025, the plant has violated its permit multiple times, so staff used existing pumps and a dry feeder to treat wastewater with sodium hydroxide, magnesium hydroxide and granular sodium bicarbonate at various points. “In wastewater, the flow never stops. As soon as we began to have a pH problem, we had to immediately pivot to be able to use existing equipment to mitigate the problem, so we weren’t violating anymore,” Gaudette said. But that’s not a safe solution and cannot be made permeant. “There is significant safety concerns with any chemical, especially sodium hydroxide, due to the risk of burns,” Gaudette said. “A large, bulk storage tank will minimize staff handling of this chemical.” Purchasing a bulk storage tank and keeping it within a proper containment area will allow deliveries of sodium hydroxide to be made by tanker truck, reducing exposure to the chemical by town employees. Councilor Peter Albert asked Gaudette if they had all of the safety equipment needed for town staff at the plant. Gaudette said they do. “What we’re trying to do is we’re trying to minimize the amount of staff touching this, the exposure,” Town Manager Paul Micali said. “That’s why we’re looking at doing the bulk bin, so they come in with the truck, we don’t touch it, they just load it, walk away.” Councilors approved the request unanimously. The town will put out for bid for the equipment needed. “We’re going to do some of the work internally, but the majority of this cost of a quarter-million dollars is because of the equipment itself,” Micali said.