Latest Mt. Pleasant Water Readings Show Improved Results
By Sean Browne
The haloacetic acid spike in two Mount Pleasant water districts that has been an escalating concern during the past year has improved, with new test results released last week showing lower levels of the substance.
Town Engineer David Smyth said that the averages in the 2019 first-quarter readings taken in February in the Kensico and Pocantico water districts have dropped below the state and federal safety guidelines of 60 parts per billion (ppb).
At the Kensico location, the water was sampled at four different locations and the readings averaged at 59 ppb, putting the average just under the threshold. Readings ranged from a low of 53.7 ppb at the hydrant at 600 Linda Ave. to 62.1 ppb at Hawthorne Elementary School.
In the Pocantico Water District, two locations were tested, 200 Lake Rd. and the water tank at the Pocantico Treatment Facility. Levels at the tank tested at 57.5 ppb and at 43.9 ppb at Lake Road, putting the average at 50.7.
“We are seeing most areas going down instead of going up,” Smyth said. “So, it is slowly going back down to where we want it.”
Last year, the last three quarterly readings in Kensico and the final two readings in Pocantico were in excess of the state and federal guidelines. The Pocantico readings last August and November were at 112.1 and 130 ppb, respectively.
Haloacetic acids are chemicals that form when chlorine or other disinfectants react with naturally-occurring organic and inorganic matter in the water, according to the county Health Department. Despite last year’s elevated readings, there was never an emergency situation, town officials said last month.
Smyth said that different measures have been considered in order to reduce haloacetic acid levels below the desired thresholds in both affected water districts. Last Tuesday, the town issued an advisory outlining some of the options. The list of options came following a recent meeting with Woodward & Curran Consultants, which the town retained last month.
In Kensico, the choices include cleaning of the interior walls and removal of sediment buildup throughout the water tanks, which would reduce the organics and the byproducts when mixing with chlorine disinfection. Installation of a mixer system in the tanks to disperse the chlorine concentrations more rapidly can also be tried.
Another course of action would be to reduce or remove pre-chlorine loading at the Commerce Street Pump Station and to apply chlorine at the tanks prior to release into the distribution system. That is estimated to be a three-day process.
Depending on the outcome of the first two steps, the town, in tandem with its consultants, could also consider changes regarding delivery of chlorination, reducing chlorine concentrations at the entry point and installing chlorine booster systems to increase chlorine levels as needed. The latter would reduce the time organics are exposed to higher chlorine concentration levels, which would decrease the potential for the creation of disinfection byproducts.
Fiber Optic communication cable could also be used to assist telemetry between the pump station and the water tank treatment system.
In the Pocantico Water District, the cleaning and removal of sediment in the tank was completed in January. The town is working with its consultants to create a recommended sampling plan throughout the treatment system to determine the areas where high disinfection byproducts are created.
Other remediation steps could include relining all water mains throughout the Pocantico distribution system and using additional treatment methods, such as ozone or chlorine dioxide to help with pathogen removal to reduce the amount of chlorine that is needed.
Smyth said that the rate of chlorination can’t be reduced too much because the water would then be more susceptible to pathogens, which can lead to serious diseases.
Filters for household use costing about $800 have also been reported to remove haloacetic acid levels, Smyth said. More information about filters as well as updates to the Mount Pleasant water situation can be found on the Water Advisory Page on the town’s website at www.mypleasantny.com.
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