The U.S. Environmental Protection Agency and the Massachusetts Department of Environmental Protection (DEP) have jointly issued a new draft wastewater discharge permit for the City of Marlborough's Easterly Wastewater Treatment Plant.
The proposed permit would require the city to complete construction of treatment facility upgrades necessary to meet discharge standards to address phosphorus pollution into Hop Brook within four years.
The Easterly plant has significant impacts on Hop Brook: during the summer up to 99% of the brook's flow is effluent from the treatment plant, and 95% of the phosphorus load to the brook comes from the plant.
Public comments on the proposed permit will be accepted until Jan. 26. After the comment period ends, EPA and DEP will respond to comments and issue a final permit.
The City of Marlborough's Easterly Wastewater Treatment Plant is a 5.5 million gallon per day wastewater treatment facility that discharges treated effluent to Hop Brook, a tributary of the Sudbury River. Hop Brook is affected by pollution from nutrients (chiefly phosphorus and nitrogen) that stimulate excess algae growth, resulting in a loss of oxygen for fish, unsightly growth and odor problems. The four ponds along Hop Brook are particularly affected.
Because of the pollution, most of the brook is unable to support its designated uses, including fishing, swimming and boating. Both state and federal clean water laws apply to the plant, so it is required to have both a federal and state permit. Currently, the plant is operating under a joint federal-state permit issued in 1988. The phosphorus limit in the 1988 permit is 0.75 milligrams of phosphorus per liter of effluent (0.75 mg/l).
In 1999, EPA issued a new permit to replace the 1988 permit. After this new permit was appealed by both the City of Marlborough and the Hop Brook Protection Association, EPA began negotiations with the DEP and the appealing parties, and withdrew the 1999 permit (leaving the 1988 permit in force).
The current draft permit is being jointly proposed, and would be jointly issued, by EPA and DEP. The proposed permit would set long-term limits for phosphorus of 0.1 mg/l from April through November and 0.75 mg/l from December through March. The proposed permit would require compliance with the phosphorus limit within four years. In the meantime, the existing plant must meet phosphorus limits of 0.5 mg/l from April through November and continue to meet limits of 0.75 mg/l from December through March.
Additional new elements in the proposed permit include toxicity limits for the effluent and a required plan by the city to control non-sewer water leaking into the city's sewer system.