Read the full article by Johanna F. Still (Port City Daily)
“BRUNSWICK COUNTY — Brunswick County will soon pay an estimated $1.2 million to replace 45-year-old filters at its Highway 211 Water Treatment Plant.
The existing sand filters have been in operation since the plant opened in 1975, only equipped to filter out turbidity and sediment. Brunswick County does not plan to enhance this plant’s treatment technology; existing filters will be replaced with exactly the same product.
Aquifer-sourced water pumped at the 211 Water Treatment Plant (WTP) contained no detectable levels of the 25 per- and polyfluoroalkyl substances (PFAS) compounds analyzed, last tested May 12, 2019.
However, finished water at the groundwater plant tested July, 5, 2017 contained 3.7 times the maximum concentration of 1,4 -Dioxane the Environmental Protection Agency (EPA) recommends in its drinking water cancer risk assessment level (this represents an advisory, not a requirement). Later that month, finished water contained no detectable amount of 1,4 -Dioxane, lower than the .35 parts per billion federal advisory.
In the two-and-a-half years since, the county has not tested for 1,4 – Dioxane at the 211 WTP. Traditional sand filters — including the filters the county soon plans to purchase — are not capable of filtering out 1,4 – Dioxane.
Still, since groundwater typically contains far less industrial contaminants compared to surface water, advance filtration technology is not always necessary.
‘The 211 Water Treatment Plant is not tested as frequently for 1,4-Dioxane as the Northwest Water Treatment Plant because it pulls its water from groundwater wells served by the Castle Hayne aquifer, which is located further south and away from industries that typically produce these kinds of contaminants,’ the county’s spokesperson explained.
More than a decade ago, the county floated the possibility of installing a new membrane treatment facility at the 211 WTP site, but this idea never materialized. Instead, the county is actively planning a $90 million low-pressure reverse osmosis system upgrade at the surface water-sourced Northwest Water Treatment Plant, while the county awaits necessary environmental permits.
A much-needed expansion is planned too, which will nearly double its capacity, from 24 MGD to 45 MGD (the planned reverse osmosis system could treat up to 36 MGD while conventional systems could produce the remaining 9MGD in a high-demand scenario).
Reverse osmosis technology is capable of removing more than 90% of known and testable PFAS compounds, March 2018 pilot test results show (nearly 5,000 persist in the environment but existing testing methodology has not yet caught up to detect each compound). Pilot tests indicated reverse osmosis could filter out 90% of 1,4-Dioxane, while other treatment methods, including Granular Activated Carbon, are less effective at removing the toxin, which is unrelated to the PFAS family.
Groundwater at 211
Capable of treating about one-fifth of the county’s total water supply, the 211 WTP typically services southeastern Brunswick County. The communities of St. James, Oak Island, Caswell Beach, and Southport receive blended water from the 211 WTP and the Northwest Water Treatment Plant, according to Brunswick County. Bald Head Island sources most of its water from its own groundwater wells and purchases water from Brunswick County as needed…”