A water treatment facility is being proposed at the H.P. Hood dairy plant on North State Street to reduce the amount of organic material the plant sends into the city’s sewer treatment plant at Hall Street.
The plant received permission Wednesday from the Planning Board to build a 4,800-square-foot building in the back of its property at 330 N. State St. It would perform pretreatment of liquid waste before it is pumped to the city treatment plant, removing organic material known as BOD, or biologic oxygen demand. The structure would hold four stalks to hold and strain the liquid, plus other equipment.
The main question that came up from a neighbor during the heating was: Will it smell?
“All tanks are covered, the pretreatment equipment is inside the building, and it is an aerobic process, we’re not generating biogas or anything like that,” said Patrick Mason of H.P. Hood during Wednesday’s meeting. He described any odor as “earthy.”
Tim Thompson, the assistant director of community development for Concord, agreed, pointing to his experience working in Londonderry, home of a huge Stonyfield yogurt plant. Pre-treatment at yogurt manufacturing plants and breweries are major creators of BOD, he said, but “it is not a significant source of odor.”
The plant current does no pre-treatment aside from balancing the pH of liquid waste, Mason said.
The Hood plant is the biggest industrial customer of Concord’s wastewater system, said Dan Driscoll, superintendent of the plant, and the city needs it to reduce the amount of organic material it sends to the Hall Street plant, the city’s main sewage treatment facility. The issue was identified when the Hood plant got its most operating permit from the city in late 2024, and was given two years to reduce its BOD level.
The plant takes milk from farms through New Hampshire and Vermont and turns it into fresh milk and other dairy products. It was built in 1956 by Concord Dairy, which sold to Weeks Dairy in 1971. Crowley Foods bought the facility in 1988 and Hood took it over in 2004, according to the official history.