Industrial Local Limits Development

Industrial Local Limits Development

A metal finishing/plating industry approached the Town of Thomaston about the possibility of discharging up to 30,000 gallons per day of process wastewater to the town’s wastewater collection and treatment system. In addition to the proposed discharge, the company also had a NPDES permit to discharge of up to 100,000 gallons per day to the Naugatuck River. The company was driven to discharge to the town's system because of new Nitrogen Limits on its NPDES permit, which would have required the company to complete major upgrades for nitrogen reduction. The town was leery about accepting the discharge as it had previously received process water with high concentrations of nickel, which caused issues with the town’s biological process at the Water Pollution Control Facility (WPCF).

The Water Pollution Control Authority hired Weston & Sampson to conduct a headworks analysis, establish technically based local limits, and prepare an individual industrial discharge permit for the company. The headworks analysis, which was conducted utilizing EPA approved methods, indicated that the town’s WPCF had sufficient capacity to accept various metal compounds (particularly nickel and copper) while maintaining appropriate reserves/safety factors for NPDES permit compliance. From the headworks loading analysis, the town and company negotiated technically based local limits that would work for both parties and which provided the town with a reserve should another industry in want to connect to the WPCF.

Uniquely, in the State of Connecticut, the EPA has delegated responsibilities for the Industrial Pre-Treatment Program and Industrial Compliance to the State, thus providing less oversight. In Connecticut, all industrial dischargers are required to obtain a SPDES permit before they can discharge to the municipal sanitary sewer collection and treatment systems. The limits which the town established for this company are substantially less than those provided by the state, as the state's limits were based on categorical determinations from the 1970s. Weston & Sampson’s experience with other New England communities indicated that the use of the categorical determinations from the 1970s can result in permit violations for metal compounds.


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