Wastewater Disposal Facilities

Effluent from the wastewater treatment facility is disposed under a Montana Groundwater Pollution Control System (MGWPCS) permit number MTX000110. Utility Solutions currently operates their facilities under this discharge permit which became effective August 1, 2005 with four outfalls. The current discharge outfalls include an Infiltration/Percolation (IP) subsurface discharge located in Elk Grove Subdivision (001), a pressure-dosed drainfield on Lot C-1 (002), a Rapid Infiltration (RI) subsurface discharge located in Rainbow Subdivision (003), and spray irrigation located at Elk Grove Subdivision (004). Limitations of the discharge are based on the amount of flow that the wastewater treatment facility is receiving. Discharge 001 at Elk Grove can be operated up to 80,000 gpd with a limit of 30 mg/L Total Nitrogen and 3 mg/L Total Phosphorus and does not require disinfection. Upon exceeding 80,000 gpd, the plant may discharge to any of the outfalls with limits of 10 mg/L Total Nitrogen, 3 mg/L Total Phosphorus, and 200 organisms/100 mL. The wastewater treatment facility has been expanded to include ultra-violet disinfection in order to meet the permit requirements.

To date, the 100,000 gpd capacity IP subsurface discharge (Outfall 001) is completed and under operation. The RI subsurface discharge (Outfall 003) is constructed to a capacity of 200,000 gpd with plans for construction in increments to a capacity of 500,000 gpd. The RI discharge is operational as of September 2010 with the completion of the ultra-violet disinfection expansion to the wastewater treatment facility. The Lot C-1 Outfall 002 is not constructed and is expected to be abandoned to make room for future treatment facilities on Lot C-1. The spray irrigation Outfall 004 at Elk Grove is not constructed and is expected to be utilized after other effluent disposals are at capacity. The current permitted outfall volume of the wastewater treatment system is 635,537 gpd. The flow capacity and effluent limitations are contained in Table 1.

Table 1: Effluent Disposal Sites