Kearns and Sons RS Aesthetics

Public hearing scheduled on groundwater discharge permit for Grantsdale subdivision


By Michael Howell

The public comment period has been re-opened and a public hearing scheduled to consider the renewal of a ground water discharge permit for the Grantsdale Addition subdivision. This is a renewal of an existing ground water discharge permit for one of the county’s largest subdivisions. The proposed facility will serve up to 181 homes and two commercial/industrial connections, with a combined average daily flow estimated at 40,000 gallons per day and designed maximum daily flow of 60,000 gallons per day. The proposed design of the facility consists of individual septic tanks on each lot (provided by each individual lot owner), individual grease traps (provided by each individual commercial/industrial connection), gravity sewer lines with a possible force main, recirculating tank(s), recirculating filter(s), dosing tank(s), distribution lines, and two 30,000 gallon capacity pressure-dosed drain fields.

Raw sewage enters the septic tanks where primary treatment (settling) occurs. Effluent from the septic tanks on each of the individual lots will be conveyed via a 4-inch gravity sewer main into a recirculating tank(s) with a 45,000 gallon capacity. Effluent is then pumped from the recirculating tank into the recirculating filters for treatment. The permittee has indicated that either a recirculating trickling filter or a recirculating sand filter will be the treatment method used by the facility.

After treatment, the effluent is either returned to the recirculation tank for additional treatment or directed into a dose tank for discharge into ground water via two pressure-dosed subsurface drain fields. Each drain field will receive up to 30,000 gpd and discharge into Class I ground water. The drain fields are in close proximity to each other and receive the same treated wastewater from the same collection system. As such, the two drain fields are designated as a single outfall.

One concern expressed by some of the respondents during the initial public comment period was that the developer was not in compliance with his previous permit and was found to be in violation, in part, by failing to install ground water monitoring down gradient from the system. The draft permit now under consideration appears to address this shortcoming by no longer requiring it. Respondents express concern about potential pollution of the ground water and subsequently the Bitterroot River and question the rationale for dropping the requirement.

Public comments are invited anytime prior to close of business January 23, 2014. Comments may be directed to the DEQ Permitting & Compliance Division, Water Protection Bureau, PO Box 200901, Helena MT 59620; or e-mailed to David Dunbar or Barb Sharpe at

A public hearing will be held on the draft wastewater discharge permit, the statement of basis, environmental assessment, and the Department’s tentative determination on Thursday, January 23 at 5:30 p.m. in the Ravalli County Commissioners Conference Room at 215 S. 4th Street in Hamilton. The department will respond to all substantive comments and issue a final decision within 60 days of or as soon as possible thereafter. Additional information may be obtained by calling (406) 444-3080.



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