Testing has again shown that Lincoln water contains excessive levels of a certain contaminant, though the level is just over the maximum and work will soon begin on a system to solve the problem permanently.
In an unrelated development, the Water Commission has restricted nonessential outdoor watering to one day a week, down from the previous two (see related story).
For several years, especially during the summer months, routine testing has shown levels of disinfection by-products called total trihalomethanes (TTHMs) above acceptable levels for drinking water. Tests in the second quarter of 2020 revealed levels of 81.9 parts per billion (ppb) while the standard is 80 ppb. The water is safe to drink, but consumption of excessive TTHMs in drinking water over many years may increase the risk of certain types of cancer and cause other adverse effects in some people. The state Department of Environmental Protection has ordered the town to fix the issue.
TTHMs are created when the chlorine (a required disinfectant) reacts with organic material in the water from Flint’s Pond. The level of organic content of the water is now twice what it was when the water treatment plant was designed. That material comes from dissolved plant matter and algae in the pond, and warmer weather accelerates the process, so global warming may be causing the slow increase in recent years. “We can only speculate,” Water Commission member Ruth Ann Hendrickson said last week.
Another possible contributing factor, she said: the water level in Flint’s Pond was very high for a time after the dam that holds back the water was deliberately heightened when Water Department Superintendent Mary Beth Wiser ordered workers to add more boards to the top of the dam some time in 2019.
“That raised the level of the pond and may have pulled decades of leaf mold into the water,” Hendrickson said last week. In fact, the water rose so much that it crept close to the pump house and also began seeping under the dam, which was upgraded in 2017. It’s unclear why Wiser had the water level raised. “I haven’t been able to get a straight story,” Hendrickson said when interviewed for an October 2019 story on the problems at the Water Department.
The department’s consultants recently completed a pilot study to evaluate options for removing the TTHMs, and they submitted their report on August 5 to the DEP, which is expected to approve the plan within three months. Knowing that the project was coming, the town approved $330,000 in bonding in late 2018 for design and installation and treatment equipment.
The DEP originally wanted the town to install a system to add chloramine to the water, but Wiser and consultants Tata and Howard “thought that wasn’t the right solution,” partly because it was more expensive and requires adding more chemicals than the other two alternatives studied, Hendrickson said.
Instead, the system will cause coagulation in the water, which will make the particles of organic matter stick together in clumps that are large enough to be caught by the filters. The new equipment will be “squeezed into the antique building” close to the pond that also houses the pumping equipment and should be operational by next summer, she said.