DEQ pushes Darby to comply with wastewater treatment requirements

by Michael Howell

The Town of Darby has received notice from the Department of Environmental Quality enforcement division that it is in violation of the Montana Water Quality Act at its wastewater treatment facility by failing to comply with the conditions and limitations of its wastewater discharge permit. According to the Notice of Violation and Consent Order signed by Mayor Nancy McKinney, Darby has reported 28 effluent limit exceedances since 2020, twenty-one of which are considered “significant non-compliance.”

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 intermittent to the Bitterroot River.

According to the Consent Order, the facility exceeded the Carbinacious Biological Oxygen Demand 5-day (CBOD) a total of 16 times. 

The exceedances included:

• CBODs exceedances

• monthly average in loading pounds per day (four times)

• monthly average concentration in mg/L (four times)

• weekly maximum in concentration (four times)

• weekly maximum in loading pounds per day (two times)

• percent removal (two times)

• permit effluent limit for pH (four times)

• permit effluent limit for E. coli (five times), all of which were considered Significant Non-Compliance           

• permit effluent limit for Total Suspended Solids (one time)

DEQ issued violation letters for each of these permit exceedances and has given the Town 60 days from the date of the September 25 Consent Order to address the violations by submitting a compliance plan and a schedule for compliance outlining the steps the Town will take to come into compliance. The plan and schedule are due no later than November 24, 2023. The plan needs to include an engineering report which includes details on implementation of optimization and/or necessary upgrades. It must also include deadlines for completion of each task including dates for submittal of any necessary design reports, plans and specifications to complete the corrective actions and completion of any construction or modification of the system, as well as submittal of as-built drawings and project certification for any construction or modification of the facility and collection system. The Town must also maintain compliance with the permit at the facility for two years following the completion of the upgrades listed. 

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. Darby must promptly correct any identified deficiency and resubmit the plan.

Each year following the Consent Order, the Town must submit an annual status report by January 31. The Town must 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.

Based on the number of significant violations DEQ calculated an administrative penalty in the amount of $40,250, but “to facilitate compliance and resolve the cases DEQ is using its discretion as allowed [by law] and is choosing not to assess the penalty for the violations.”

In lieu of an assessment of the administrative penalty, the Town has agreed to “stipulated penalties” which include a penalty of $350 for each day the plan is late and $500 for each day any deadline in the plan is delayed without prior approval of the delay by DEQ.

Mayor McKinney said that the Town has been working for the last five years on a sewer improvement project that will address all the problems related to DEQ’s permitting concerns. She said the Town expects the project to go out to bid in late winter or early spring next year.

“Part of our compliance plan,” she said, “will involve setting some specific dates within certain months where certain milestones will be met. That will help the Town and our engineer get the project completed and eliminate the issues that we are having.”

She said the Town’s engineering company, Triple Tree Engineering, has been successful in getting $3 million in grants from ARPA and DNRC for the project. She said the project will address DEQ’s concerns at the lagoon but will also include inspection of the sewer’s forced main line, which she doesn’t believe has ever been inspected, installing a new lift station and fixing some filtration problems throughout the system.

McKinney said the lagoon work would involve removal of sludge and replacement of some valves and that she expects to have the plan for DEQ done by the November 24 deadline.

No Town Council members responded to emails sent last Friday seeking comment on the issues at the wastewater treatment facility. The next Town Council meeting was set for Tuesday, October 10, too late for inclusion in this story.