Showers and thunderstorms likely - heavy rainfall is possible, especially this evening. Low 67F. Winds SSW at 5 to 10 mph. Chance of rain 90%. Rainfall may reach one inch..

Showers and thunderstorms likely - heavy rainfall is possible, especially this evening. Low 67F. Winds SSW at 5 to 10 mph. Chance of rain 90%. Rainfall may reach one inch.

BENNINGTON — Wastewater from several businesses will be tested over a concern raised about the town wastewater treatment plant and its discharge permit limits.

In some cases, according to Town Manager Stuart Hurd, businesses could be required to install a system to pre-treat water before discharge into town sewer lines. Businesses being tested include dairy manufacturers, distilleries and breweries, and possibly others, he said.

“The current situation was brought to my attention by the staff as a concern to be managed,” he said in an email.

Hurd said in a recent notice to the Select Board that “over the last six to 12 months, our staff at the [wastewater treatment plant] have been concerned about the biochemical oxygen demand in our influent [water entering the plant] and its impact on our effluent,” or water leaving the plant on Harrington Road.

After treatment to remove impurities, the plant discharges water into the Walloomsac River.

Biochemical oxygen demand is defined as the amount of oxygen consumed by bacteria and other microorganisms while they decompose organic matter under aerobic conditions.

The higher the BOD, the more rapidly oxygen is depleted in a stream, leaving less oxygen for higher forms of aquatic life, such as fish and plants.

Thus far, Hurd said, the water leaving the town plant and has not exceeded the permitted level of biochemical oxygen demand, which is 30 milligrams per liter of water.

However, he informed the board that “our effluent levels hit a high in May of 23 [milligrams per liter]. [biochemical oxygen demand] is impacted by organics in the wastewater. High BOD level of discharge from certain businesses is our focus.”

“We will be contacting businesses to sample discharges to see if any of our businesses are currently discharging an extremely high BOD.”

Hurd said the businesses to be tested “include dairy manufacturers, distilleries, and breweries. There may be others. Pre-treatment of the waste may be required.”

Hurd said Wednesday that seven businesses have been notified their wastewater will be tested.

“The town staff will arrange for a grab sample,” he said in an email. “Testing has not yet started, as far as I know.”

The extent of any required pre-treatment system for a business could vary significantly, Hurd said.

“It may be as simple as a holding tank with aeration added before discharge,” he said. “Extreme levels of BOD may require a more expensive treatment or a change in the process.”

Jim Therrien writes for Vermont News and Media, including the Bennington Banner, Manchester Journal and Brattleboro Reformer. Email jtherrien@benningtonbanner.com

Jim Therrien reports for the three Vermont News and Media newspapers in Southern Vermont. He previously worked as a reporter and editor at the Berkshire Eagle, the Bennington Banner, the Springfield Republican, and the former North Adams Transcript.

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