Brunswick County’s Commissioners voted unanimously to approve construction of a low-pressure reverse osmosis plant at the Board’s budget workshop Thursday, moving forward with providing a forward-thinking, long-term water quality solution for all customers that receive water from Brunswick County.
On April 16, the Board received a report from CDM Smith, the firm hired to research and review data, conduct pilot tests and consult with experts regarding advanced water treatment methods and the presence of chemicals in the Cape Fear River, from which Brunswick County draws water. CDM Smith recommended low-pressure reverse osmosis (LPRO) as the most efficient and cost effective advanced water treatment addition to the Northwest Water Treatment Plant.
After hearing the recommendation made Apr. 16, the Commissioners and County staff extensively reviewed CDM Smith’s report and findings, along with information about the effectiveness and cost of other treatment methods. After reviewing and researching, County staff also recommended LPRO, and the Board of Commissioners voted May 10 to move forward with implementation of LPRO as the most cost effective long-term solution for Brunswick County water treatment.
The report from CDM Smith showed that the pilot LPRO system set up at the Northwest Water Treatment Plant removed 45 PFAS compounds to as close to non-detectable limits as possible. In one round of testing, all 45 PFAS compounds were removed to non-detectable levels; in a second round of testing, 44 of 45 PFAS compounds were removed to non-detectable levels. In the testing results, the total sum of 45 perflourinated chemicals was 11 nanograms per liter. All but one of the perflourinated chemicals were not detected in the treated water using the best technology currently available, representatives from CDM Smith told the Commissioners.
Testing was completed to determine the presence and amount of more than 45 compounds, including GenX, Nafion Byproduct 1 and Nafion Byproduct 2, Perflourooctanesulfonic acid (PFOS), Perflourooctanoic acid (PFOA), 1,4-Dioxane and PFMOAA in the water before and after treatment by the LPRO unit. The testing results also showed a 94-percent removal of 1,4-Dioxane, taking it from 3.2 µg/L before the LPRO treatment to 0.2 µg/L after treatment. Other substances, including the insect repellant DEET, the herbicide Atrazine, and the seizure medicine Carbamazepine were not detected in the LPRO-treated water.
In recommending LPRO, CDM Smith noted that its operational and maintenance costs are less than other methods that would require frequent changing of filtration material, and that using LPRO after the County’s current filtration methods would cost less than a higher-pressure system that would be needed to treat brackish groundwater.
Implementation of LPRO is estimated to cost approximately $99 million, with additional operations and maintenance costs of approximately $2.9 million per year.
“The net present worth, the life cycle cost if you will, of reverse osmosis is almost half of the other [treatment methods and method combinations considered],” Bill Dowbiggin, Senior Vice President and Senior Environmental Engineer with CDM Smith, told the Commissioners in April.
Preliminary design work has begun, with final design work expected to begin in September. The application process for NCDEQ to modify the County’s existing discharge permit began in February, and has proceeded with no “red flags” from regulators. Bidding and construction of the project is expected to begin in June of 2019.
Brunswick County had previously planned to expand the capacity of the Northwest Water Treatment Plant to meet the demand of its customers, prior to the discovery of GenX in the Cape Fear River. These expansion plans remain in place, and the proposal for LPRO includes plans to accommodate that increase in capacity.
In addition to serving over 40,000 retail customers, Brunswick County has ten wholesale utility water customers that serve over 30,000 additional retail customers within Brunswick County. Brunswick County is evaluating treatment options that address water quality issues affecting all of the more than 70,000 customers within the County, rather than just a small subset of customers. This approach allows Brunswick County to take advantage of economies of scale associated with the construction costs of additional water treatment methods.
Brunswick County has also evaluated treatment options that are effective on a number of chemicals found in the Cape Fear River, including some only recently discovered. In considering these options, as well as the potential for new chemical discoveries or regulatory changes in years to come, Brunswick County is ensuring that the treatment method selected will provide a long-term solution for the needs of all customers who receive water from Brunswick County or one of its wholesale customers, now and in years to come.
Updates about these water treatment improvement plans, Brunswick County’s water testing results and GenX in general are posted online at https://www.brunswickcountync.gov/genx/ and emailed to those who have signed up for notifications at http://eepurl.com/ZT6tb.