Residents of Sipayik and Eastport should now be seeing an improvement in the quality of water supplied by the Passamaquoddy Water District (PWD), particularly in the summer and fall, as two new granular activated carbon (GAC) filters arrived last week at the PWD's water treatment plant in Perry and went online on August 31. The new filters should not only help with the color, odor and taste of the water but also should reduce the levels of total trihalomethanes (THMs), a possible carcinogen, in the drinking water. Concerns about the drinking water quality at Sipayik had led to the enactment this past spring of legislation that allows the Passamaquoddy Tribe, without needing state approval, to tap into a groundwater aquifer in Perry to provide drinking water.
      The $818,000 cost for the GAC filters was covered through funds provided by Wabanaki Public Health and Wellness, the Drinking Water State Revolving Fund and the Maine Drinking Water Program. The filters were supplied by Westech of Salt Lake City, Utah, and the delay in having the filters installed, which had been anticipated for June, was caused by issues involving Westech, according to Mark McCluskey of A.E. Hodsdon in Waterville, a consulting engineering firm for the PWD, who is the licensed operator for the water treatment plant.
      The GAC filters may need to be replaced every year, at an estimated cost of $60,000. With the PWD no longer having to pay property taxes in Eastport and Perry, following enactment of the legislation last spring, the quasi-municipal water district may have the funding to cover the cost. Last year, the PWD's tax bill was $43,000 in Eastport and $23,000 in Perry. McCluskey notes that it's possible that the GAC filters may not need to be used during the winter, which could extend their lifespan.
     

Filtration system outlined
Two nine-foot diameter tanks hold the granular activated carbon, which are small particles that absorb contaminants and organic compounds out of the water. Both GAC filters will be run most of the time.
      The PWD also recently acquired an analyzer that measures the amount of total organic carbon in the water, so that the water district can compare the levels in the raw versus the treated water. McCluskey notes that knowing the total organic carbon levels will help with fine-tuning the amounts of coagulation chemicals that are used in treating the water.
      The day the first GAC filter was installed, the raw water coming into the plant had 8.3 parts per billion (ppb) of organic carbon. After running through the plant's first filtration system the level was reduced to 3.6 ppb, and after going through the GAC filter it was down to 1 ppb. While the plant's existing filtration system reduced the carbon level by nearly 60%, with the GAC filters added the reduction was nearly 90%.
      While organic levels in the lake water are low during the winter when the lake is frozen, at other times of the year heavy rains will cause run-off from farm fields, and strong winds can stir up the shallow impoundment area. The water temperature and when the lake turns over in the fall and spring can also affect the level of organics, according to McCluskey.
      The water coming into the plant comes from two intakes pipes in the impoundment area by the stream flowing from Boyden Lake. Outside of the plant, the water then goes through a roughing filter made up of graded stone that removes organic compounds and reduces the turbidity. Inside the plant are clarifiers and multimedia filters consisting of sand, stone, garnet and anthracite that take out most of the remaining organic compounds and turbidity. With the addition of the GAC filters, the water now flows through them before it is chlorinated and goes out into the distribution system. With more of the organic compounds removed from the water, less chlorine will need to be used to treat the water, which should improve the taste. The PWD keeps its chlorination levels as low as possible to help reduce the THM levels, McCluskey notes.
     

THM issues
THMs are formed when organic compounds in the water come in contact with chlorine, which is added as a disinfectant at the treatment plant. Different THMs that can be formed are classified as either possible or probable human carcinogens by the U.S. Environmental Protection Agency (EPA). While the water district had struggled for years with the issue of high THM levels in the water, McCluskey points out that, since the PWD had a study conducted in 2008, there have not been that many times when the PWD's water quality tests exceeded the 80 parts per billion (ppb) maximum allowable limit set by the EPA for total THM levels. Over the past 13 years there were eight times when the maximum allowable levels were exceeded. The last time that the PWD water tested over the THM limit, at 81.6 ppb -- just over the allowable level -- was in November 2020. The PWD currently is in compliance with all Safe Drinking Water Act requirements.
      However, twice during the fall of 2021 the tribal government had water samples from 10 locations at Sipayik, where the PWD does not take samples, tested by a private laboratory. All of the samples tested above the THM limit in October, but none of them were over the limit in November. McCluskey notes that water samples that the PWD takes at the meter pit that measures the amount of water going into the water lines at Pleasant Point had been below the THM limits, while some of the samples taken from water lines at Sipayik exceeded the limit. He observes that if water becomes stagnant in the water lines, particularly dead-end lines, then THMs can form. Having bleeder valves installed on those lines, which are maintained by the tribal government, not the PWD, would help keep the water from stagnating. Bleeders release water in the lines and help keep the water fresh.