The Town of Darby submitted a compliance plan to the Department of Environmental Quality (DEQ) last Thursday in response to the notice of violations that the agency issued last September 25. Darby owns and operates a three-celled lagoon system equipped with solar bee mixers in each cell. The lagoons, located northeast of Darby, were constructed in the 1960s and upgraded to the current three-cell lagoon system in 1979 and are operated as a batch discharging facility adjacent to the Bitterroot River.
The notice of violation cited 28 effluent limit exceedances since 2020, twenty-one of which are considered “significant non-compliance” and gave the Town 60 days to submit a compliance plan and a schedule for compliance outlining the steps the Town will take to come into compliance.
Mayor Nancy McKinney said that an amended 65% plan had been submitted and that a 95% plan will be submitted by January 15. DEQ will review the plans and provide a written response to the Town that either approves the plan or identifies deficiencies in the plan that must be corrected. The Consent Order signed by the Town also requires an annual status report and requires the Town to notify DEQ of any anticipated delays within 10 days of becoming aware of reasons for the delays and demonstrate that the delays are due to reasons beyond the Town’s control and that it has made all reasonable efforts to avoid the delay. It must also propose a reasonable new deadline. According to the Consent Order, the Town must also maintain compliance with the permit at the facility for two years following the completion of the upgrades.
McKinney said that most of the problems were related to controls at the lagoon system. “We can’t control how the water moves from one lagoon to the other,” she said. “It’s supposed to have controls that regulate the timing of the flows so that it remains a sufficient amount of time in each lagoon.” She said the installation of control boxes and new valves will address that problem. The plan also calls for installation of a strainer before the water reaches the lift station to screen out inorganic material as well as replacing the current lift station.
“We will also be removing a foot of sludge from off the bottom of the lagoon to increase the working capacity of the system,” she said. The project is planned to be totally funded by a combined amount of $2,992,082.00 in ARPA, MCEP and RRGL grant funds.
The Town stated in a Dec. 4 letter to DEQ, “We realize the 2023-2025 project planned may not address all current problems, therefore the Town is beginning to plan for a second ‘future’ sewer project to address remaining issues that may not be resolved by the 2023-2025 project. The ‘future’ project components will be dependent upon the successful outcome of the 2023-2025 project to resolve the discharge permit violations of CBOD, Ph, TSS and E. Coli.”
The Town is looking at a couple of planning grants in this regard to have a PER written to address effluent treatment (E. Coli)(if necessary), improvement and extension of the sewer main along Highway 93 North to allow future growth in the most efficient manner possible and to further reduce infiltration of ground water. All future projects are dependent upon available funding but this project is forecast to be in 2026-2028.