August 9, 2002
Mr. Robert Smith
Commissioner of Public Works
Department of Public Works
City Hall - 45 School Street
Brockton, MA 02401
Dear Mr. Smith:
The National Pollution Discharge Elimination System (NPDES) Permit Unit has reviewed the July 2002 report titled Facilities Assessment - Brockton Advanced Wastewater Treatment Facility. We are concerned that the report does not adequately address conditions which we anticipate will be included in future NPDES permits issued to Brockton. while it is the responsibility of the Massachusetts Department of Environmental Protection to review and approve facilities planning documents, we believe it is important to consider the following issues in your long term planning.
The receiving water for Brockton's wastewater discharge is dominated by the effluent during low flow conditions. There is evidence that the receiving water does not support aquatic life uses designated in the Massachusetts Water Quality Standards. Toxicity and nutrient loadings are a primary concern relative to water quality. The existing permit contains a 1.0 mg/l phosphorus limit but future limits will be much more stringent. The new national criteria recommendation for receiving water concentrations of total phosphorus is 0.024 mg/l. The existing permit expires in 2004 and the reissued permit will almost certainly contain a much more stringent water quality based phosphorus limit.
In addition, nitrogen loadings to Mt. Hope Bay are a significant concern. A Total Maximum Daily Load (TMLD) will be established for Mt. Hope Bay in the next few years that will likely require significant reductions in current nitrogen loadings. Given that the Brockton wastewater treatment facility has been estimated to contribute as much as 30% on the nitrogen loading to Mt. Hope Bay, there is high likelihood that the total nitrogen limits will be incorporated in future NPDES permits.
The fact sheet accompanying the existing NPDES permit issued in September 1999 anticipated these issues and stated that any planning for additional wastewater abatement facilities should consider options for providing high levels on control for both phosphorus and nitrogen. Brockton's current planning process should evaluate treatment alternatives for achieving low levels of total phosphorus and should ensure that treatment alternatives are compatible with achieving low levels of total nitrogen.
While the current permit does not contain a flow limit, other parameter limits are based on a design flow on 18.0 MGD. The reissued permit will contain a flow limit. An increase in the design flow will not be authorized without a determination that toxicity and nutrient issues can be addressed to a level that will result in full attainment of the designated uses of the receiving water,
If you have any questions, please contact me at (617) 918-1875 of David Pincumbe at (617) 918-1675.