TEWKSBURY — Resi­dents will be receiving the next quarterly notice from the Tewksbury Wa­ter Department in the mail next week, informing them of a violation re­ceived from the Massa­chusetts Department of Environmental Protection.

According to Scott Brinch, Assistant Director of Utilities for Tewksbury, the water department’s testing of the town’s water supply in the fall revealed a higher-than-normal lev­el of TTHMs, trihalometh­anes, a byproduct of the disinfection process. Since the EPA tracks these num­bers on a quarterly basis as a rolling average, Tewks­bury’s levels still show above the required limit on paper, triggering the notice.

“The EPA requires us to send this notice, which uses specific language,” said Brinch.

A delay in obtaining the mandated cardstock due to supply chain problems, combined with printing issues and postal delays due to the holiday have created a challenge getting the mailer out to residents before the holiday.

“Residents should see the cards this week,” said Brinch.

Conditions in the source water for Tewksbury, the Merrimack River, contributed to the issue late summer.

“There is more organic material than usual in the river,” said Brinch, noting that other communities who also rely on surface water for their drinking water supplies have experienced this challenge.

Extreme weather conditions this summer are factors.

“The Total Organic Com­pounds in the Merrimack are at the highest level anyone can remember,” said Brinch in an earlier interview.

Issuance of the notice is required by the EPA, and is a standard procedure, according to Brinch. He did explain that this is not akin to a boil water order or an immediate health threat. When the elevated TTHM level was detected, the water treatment facility did a study of its pre-treatment process.

Brinch said that some improvements were able to be made to the efficiency of the pre-treatment, reducing the amount of chlorine added to the wa­ter at the onset of the process and extending the amount of time the water moved through the treatment process.

According to Brinch, raw water must come in contact with the chlorine for a specified amount of time in order to meet EPA regulations for water safety.

Brinch explained that TTHMs are formed when chlorine, which is added to drinking water to combat bacteria, combines with organic material in water over time. When water sits for a period of time, TTHMs can form. TTHMs are made up of volatile organic compounds which react with the chlorine. These compounds are called “vola­tile” because they react vs. being inert, or non-re­ac­tive.

It would take many years of exposure to TTHMs at a higher than recommended level to po­tentially cause an issue, but the notification is re­quired regardless.

Since the EPA looks at the totals based on four quarters, the average will take a few quarters to sort out. Once the reading from Q3 rolls off, the re­ported numbers will go back to normal levels. Several heat waves and significant rain this season have contributed to excessive growth of plant material in the Merri­mack River. Other material in the water includes silt, clay, detritus (decomposing matter such as dead animals), and other solids.

For perspective, TTHMs are present in swimming pools, bottled water that comes from a municipal source, commercial products that use water in their production, dairy products, and through in­halation, according to the World Health Organiza­tion. It is a challenge for all water systems; the chlorine is needed to disinfect the water, but over time, the chlorine binds with the naturally occurring components in water to create these additional compounds.

The water treatment plant at Merrimack Drive has the highest rating for water purification given, so residents should feel confident in their drinking water supply. The plant has multiple phases of water treatment starting with powder activated car­bon to pre-treat the source water, granular carbon which traps solids, and aeration blowers which strip the TTHMs out of the water.

Brinch encourages anyone who is concerned or has questions to call himself or town chemist, Me­lissa Woodbury at 978-858-0345.

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