Tuesday, January 26, 2010

Increases in Discharge and TMDL

The discharge permit for the Marlborough treatment plant, which also serves Northborough, was modified in November, 2009 to allow a 40% increase in the wastewater the plant discharges to the Assabet River. The law requires that the permit modification, issued under the state and federal Clean Water Acts, contain sufficient limits on pollutant discharge to enable the river to meet its water quality standard. The river does not yet meet this standard (Class B—clean enough for fishing and swimming), due primarily to the phosphorus contained in the wastewater discharges from four municipal treatment plants.


Why when the Assabet River does not meet the current clean water standards would this plant be allowed to dump more pollutants into our river.

We thought we were talking about TMDL. The Total Maximum Daily Load of phospourus in the river.

The discharge of phosprous is measured in mg/l (milligrams/liter)
A 40% increase in (liters) without a decease in (milligrams/liter) leads to a 40% increase in phospourus.

The current permit includes an annual average flow limit of 2.89 MGD and a 54 month compliance schedule for meeting the April- October 0.1 mg/l monthly average total phosphorus limit. Because the compliance schedule for meeting the new phosphorus limit was a contested condition, the schedule did not become effective until May 17, 2006, making the final compliance date November 17, 2010. An interim total phosphorus limit of 0.75 mg/l average monthly is in effect for the months of April- October. The monthly average total phosphorus limit of 1.0 mg/l for the months of November- March was required to be met within one year of the issuance date of the permit.


Because of the flow increase, EPA made changes to the effluent limitations to ensure that the discharge does not exceed the wasteload imposed by the TMDL nor exceed applicable water quality standards. The specific changes are described below.

Total Phosphorus

The total phosphorus concentration limits in the permit modification have not been changed, but mass limits have been added, calculated using the concentration limits and a flow of 2.89 MGD. In order to achieve these mass limits as the discharge flow increases, the facility must achieve ever-lower concentrations of total phosphorus, down to 0.07 mg/l to achieve the summer limits at the new design flow and 0.7 mg/l to achieve the winter limits at the new design flow.


Status Quo is not good enough. The river does not currently meet the Class B standard (clean enough for fishing and swimming).

Why is this plant still not being held to a year round limit of 0.07mg/l. The technology is available.

If the City of Marlboro can not afford to not to pollute our river. Then we say they can not afford to continue with this unchecked development.

Common sense tells us that some of the money from all this development, which is currently going to line the pockets of developers and politicians, needs to be redirected towards correcting the problems with this and other wastewater treatment plants along this river.

Enough is enough the Assabet River can no longer be Marlboro's or anyone else's sewer.


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