Mountaire Farms is asking Delaware Department of Natural Resources and Environmental Control to approve two permits to facilitate upgrades to the wastewater treatment plant at the poultry processor’s Millsboro plant.
John Rebar of DNREC’s Groundwater Discharge Section said the upgrades are in response to a 2017 failure at Mountaire’s wastewater treatment facility. Mountaire is also subject to a class-action lawsuit from neighboring property owners over groundwater contamination related to the wastewater system.
In response, DNREC required Mountaire to make short-term and long-term upgrades to the plant.
At a May 21 virtual hearing, Mountaire presented its plans and requested a spray irrigation construction permit and to modify its spray irrigation operations permit.
John Reid, president of Reid Engineering, speaking for Mountaire, said the purpose of the project is to increase the efficiency of Mountaire’s wastewater treatment plant.
Reid said the plant upgrades would provide 96 percent nitrogen removal efficiency, as opposed to the 75 percent to 85 percent the plant removes now. He said this would reduce the system’s average total nitrogen concentration by more than half, from 21.3 millgrams per liter to 10 milligrams per liter.
Mountaire is proposing to upgrade its pretreatment facilities. Reid said pretreatment removes solids, fats, oils and grease before effluent goes to final treatment. Pretreatment upgrades would include three new flow-equalization tanks and three flotation cells to improve flow for final treatment, and remove solids and oils. Reid said the new flow-equalization tanks are 12 times larger than the existing tank.
The current system includes a 3.5-million gallon reactor tank in a two-stage system. Reid said the upgrades will change that to a four-stage system, as pretreated wastewater will pass through four reactors to remove nutrients.
The new reactor system will have a volume of more than 10 million gallons. Reid said wastewater would also go through the clarifiers and then to a denite filter system and an ultraviolet disinfection system, which both further remove nutrients, before the water is sprayed on a 900-acre field adjacent to Mountaire’s Millsboro plant.
Reid said Mountaire is also upgrading its sludge disposal system, building an additional 3 million-gallon aerobic digester tank, which converts sewage sludge into compost. After passing through a digester tank, the sludge would then go into three new screw presses, which dewater the sludge and convert it to compost.
Finally, Reid said Mountaire will add a second storage pond that can hold 22 million gallons of treated wastewater. He said this will give Mountaure 44 million gallons of storage capacity.
Rebar said as part of the permit, DNREC has established a monitoring schedule to ensure what is being sprayed meets DNREC standards, as well as provide a written report to DNREC within 60 days detailing any effects from the plant on groundwater, among other requirements.
Public record open
While public comment was not taken at the May 21 virtual hearing, DNREC is leaving the record open until Monday, June 22. Comments have already been received.
Chase Brockstedt, who represents more than 800 members of the class-action lawsuit against Mountaire, said in a letter submitted as part of the hearing record, “Neither of the proposed permits addressed the ongoing public health crisis and nuisance conditions caused by Mountaire’s wastewater practices. Instead, the proposed spray irrigation permit essentially allows Mountaire to continue business as usual, polluting its neighbors’ wells and air with authorization by DNREC.”
Brockstedt opposed the permits, saying the proposed operations permit contains numerous deficiencies, including having no requirement for effluent storage to ensure spraying is not conducted in the winter and does not require that Mountaire supply an alternative water supply for contaminated drinking wells. In addition, he said, the proposed permit does not require reserve spray fields, does not specify there must be buffers between the spray fields and residents and adjacent waterways, and does not provide for enough analysis of the surface water, groundwater and a transport model for nitrogen.
Brockstedt said the construction permit is confusing and is missing key elements. He said the design of the plant upgrades is not shown to be effective in achieving permitted limits in cold-weather conditions, the sludge handling equipment is not of sufficient capacity, and the nitrogen removal is not as low as it could be.
Additional data and public comment can be submitted at https://dnrec.alpha.delaware.gov/events/684/virtual-public-hearing-mountaire-farms-on-site-wastewater-treatment-and-disposal-system.