BRUNSWICK COUNTY — Last year’s record rainfall partnered with unprecedented growth has exposed shortcomings in Brunswick County’s northern sewer system.
Now under a state-imposed moratorium, issued earlier this month, Brunswick County’s Northeast Wastewater Treatment Plant (NEWWTP) is not permitted to accept new sewer line extensions until it obtains permits needed for its expansion in the fall.
The county is working on submitting an action plan to “immediately” allow new sewer line extensions on a case-by-case basis — if approved by the Director of Water Resources.
Under 15A NCAC 02T .0118, wastewater treatment systems must obtain all permits necessary to expand operations and submit a construction schedule prior to exceeding 90% of their permitted hydraulic capacity in the previous calendar year. The law also mandates that an engineering evaluation must be submitted before 80% yearly capacity is reached.
According to a DEQ spokesperson, the county has not yet submitted an engineering evaluation, construction schedule, or obtained the required permits to expand capacity at the plant, as outlined by state law. On Friday, Brunswick County Manager Ann Hardy said the county can provide a construction schedule immediately. She said the county is still waiting on its final NPDES permit, expected in September.
Still under design
In January, Brunswick County’s sewer expansion consultant, McKim & Creed, announced it had completed 60% of the design process. Work on completing the required National Pollutant Discharge Elimination System (NPDES) permit application– requesting added capacity and a renewal– was still ongoing.
But in the year that had just wrapped up, the plant treated an average 92.3% of its permitted capacity.
- Quick facts:
- For 90 days in 2018 (about 25% of the year), NEWWTP exceeded its design capacity
- Highest flow in 2018, at 200% capacity, recorded after Hurricane Florence on September 16, 2018
- NEWWTP daily flows exceeded design capacity for a 17-day streak, between June 24 and August 12
- The Wilmington region broke a 141-year-old precipitation record by 18 inches in 2018, with 102.4 total inches of rain, according to the National Weather Service
- In January 2019, flows exceeded design capacity for seven total days.
- Since January, daily flows have not exceeded design capacity
- Between 2017 and 2018, with population increasing by 4.6%, Brunswick County was the fastest-growing county in North Carolina, according to U.S. Census data.
- Population in Brunswick County has increased by 25.9% in an eight-year period, from 2010-2018
Rainfall, flow from H2GO
Capacity reached as high as 110% in December 2018, resulting in a state violation for exceeding monthly treatment limits. Monthly monitoring data, provided by the Department of Environmental Quality (DEQ), shows the plant exceeded its design capacity 23 days that month.
In a remission request for that violation, Brunswick County’s utilities director told DEQ the exceedances could be attributed to record rainfall. No environmental damage resulted from the exceedances, according to the remission request.
Also, beginning in October 2018, Brunswick Regional Water and Sewer H2GO was treating less wastewater at its plant in Belville as NEWWTP’s was on the rise. Flow treatment reductions at H2GO and increases at NEWWTP between October and December 2018 nearly directly correlate, according to both plant’s monitoring reports.
According to H2GO’s most recent yearly monitoring report on its Belville plant, it diverted an average of 278,000 gallons-per-day to NEWWTP between May 2017 and May 2018. During that same timeframe, the Belville plant treated an average of 338,500 gallons-a-day, about 85% of its permitted capacity. H2GO is locked out of expanding its treatment capacity — at 400,000 gallons-a-day — until 2040. This is due to a legal agreement between H2GO and the county, signed in 2001.
Brunswick County’s April remission request states the county expressed concerns that DEQ was permitting a significant amount of flow to the Belville plant that was actually being rerouted to the county’s Navassa plant. At the permitting stage, this leaves the county without the ability to regulate flow, according to the county’s request.
However, H2GO’s reduced flow is just one factor. Inflow and infiltration (I&I), or stormwater extraneously entering the sewer system, remains a pressing concern for the county’s utility partners. Research published in January by Dr. Larry Cahoon, a UNCW biologist, shows heavy rainfall correlates to increased I&I in central wastewater systems in North Carolina.
Though I&I is normal in wastewater systems, persistent I&I problems can point to weaknesses in a system.
Flows down this year
So far in 2019, flows have tapered off. For seven total days in January, NEWWTP treated over 100% of its design capacity. The highest recording in 2019 was on Jan. 3, at 114% of the plant’s design capacity.
Though the plant treated an average of 92% of its permitted capacity in January, flows have dipped down in the spring months compared to the same time period last year.
On Monday, Brunswick County announced it held a meeting with representatives from all of NEWWTP’s participants: Northwest, Navassa, H2GO, and Leland. The county’s press release states reduced rainfall patterns have helped reduce flows so far this year:
“Brunswick County has already taken steps with its wholesale customers to reduce flows tributary to the plant. Also, due to a more normalized rainfall pattern this year instead of the record rainfalls occurring during calendar year 2018, flows into the plant have dropped dramatically. All the participants agreed to provide information to the County so that an action plan may be compiled and submitted to the State regulators that outlines justifications for allowing the issuance of sewer extension permits immediately.”
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