RAE WSD Groundwater Modeling

In 2018, the RAE Water & Sewer District enlisted the services of AESI to complete field evaluations as well as preliminary groundwater modeling to estimate the impacts of new infiltration galleries in a planned location to the south of the Woodland Park Subdivision. AESI evaluated infiltration rates, performed groundwater monitoring and geotechnical evaluations, identified potential alternatives, and created a groundwater model to estimate the impacts to the water table from the introduction of the treated effluent at the proposed gallery site.

AESI was again selected in late 2018 to proceed with the planning, design, and construction oversight services for an estimated $3M expansion to the treated effluent disposal elements of the RAE wastewater treatment plant. The RAE wastewater treatment plant currently is designed to treat up to 200,000 gpd through a sequencing batch reactor (SBR) system which then disposes of the treated effluent through infiltration galleries (like a drainfield). The new infiltration gallery project consists of a force main pipeline, new infiltration galleries, and associated valving and pumping revisions. The project was reviewed and funded through the Montana Department of Environmental Quality (MDEQ) State Revolving Fund (SRF) Program and as such, the scope of work included updates to an existing Preliminary Engineering Report, Uniform Application (funding), planning, engineering design, permitting, and assistance with construction administration, construction staking, and construction field observations. The new infiltration gallery doubled the existing disposal capacity in anticipation of future expansion of the wastewater treatment plant as identified in an earlier PER.