State approves permit modifications for digesters at four swine operations


The North Carolina Department of Environmental Quality Division of Water Resources (DWR) has approved permit modification requests to install anaerobic digesters at four animal feeding operations participating in a biogas processing project with Align RNG, LLC.  After extensive review of the applications and consideration of community concerns, DWR added additional sampling conditions and site-specific changes to the best management practices.

Four permitted swine operations, located in Duplin and Sampson counties, submitted applications to DWR to modify their existing permits. Three of these facilities requested to install new in-ground, synthetically-lined and covered anaerobic digesters. The fourth facility requested to cover an existing synthetically-lined lagoon.  

DEQ conducted enhanced public outreach, environmental justice analysis and held a public meeting and comment period to provide an opportunity for community input.  DEQ staff reviewed the concerns raised by the public and carefully evaluated the permit modifications to address the concerns within the existing authority of the agency and applicable state rules and regulations. 

DWR staff conducted an additional on-site inspection at each farm to determine current compliance and examine the specific location and operation impact of each digester.  DWR has determined the digesters will be a significant step toward achieving the criteria for environmentally superior technology standards. In addition to methane capture, the proposed digesters would serve as additional treatment units and reduce hydrogen sulfide gas in the waste stream, which should reduce odors in the waste storage lagoons as well as in the animal barns which flush with the recycled wastewater.  

In order to document the pollutant reduction and treatment effectiveness of the anaerobic digester, three of the final permits include an additional requirement for quarterly nutrient and pathogen sampling of the digester influent and effluent.  Waters Farm–M&M Rivenbark Farm (AWI310035), Benson Farm (AWI310039) and Farm 2037 & 2038 (AWI820466) will be required to conduct the sampling for the first two years of digester operation.

Based on the site inspections, the Benson Farm (AWI310039) and the Kilpatrick Farm 1, 2, 4, & 5, & Merritt Farm (AWS820005) are required to submit a report to the Division within 180 days of permit issuance of any additional best management practices (BMPs) implemented on specific sprayfields (pulls) to further reduce risk of off-site impacts to neighboring properties and the community.  The BMPs may include planting of vegetative buffers along roadways and residential property lines, use of hose-drag land application method, increase of land application setbacks, and reducing or eliminating use of these specific pulls for irrigation using traveling gun/reels. 

The permit modifications do not allow for expansion in the steady state live weight at any of the facilities and continue to be non-discharge permits, which prohibit off-site discharge of waste.  

The final permits, meeting report, and other related documents are available at