Butte, Montana

In 2012, WET was hired by Butte Silver Bow (BSB) to evaluate the impact of land use practices in areas overlying the Parrot Tailings, specifically the irrigation of the Civic Center ball fields and storage of snow on county property near the ball fields.  The Parrot Tailings are remnants of the historic Parrot Smelter that operated in Butte, Montana along the banks of Silver Bow Creek in the late 1800’s/early 1900’s. Tailings, slag, and miscellaneous mine waste were left in place after the smelter shutdown and continue to serve as a major source of contamination to Silver Bow Creek.  WET conducted a study to evaluate the extent and impact of infiltration from various sources on the Parrot and included background data collection and review, evaluation of infiltration parameters, installation of soil borings and lysimeters, and weather parameter collection. In addition to the design and construction elements for the Parrot Tailings, WET developed a sampling and analysis plan, health and safety plan, and installed 25 new wells along the Silver Bow Creek corridor to support a baseline characterization and remedial performance evaluation of groundwater and surface water along portions of Silver Bow Creek impacted by historic mining. In addition to the 25 new wells, 50 existing monitoring wells were included in the monitoring network, along with five surface water stations. The monitoring data was used to develop a comprehensive conceptual site model, groundwater potentiometric surface maps, water level difference maps, isopleths depicting groundwater plume(s), and establishment of groundwater trends over time. WET completed the installation of all new wells in November of 2017 and completed the first round of sampling at all locations in December of 2017.

WET is currently serving as the lead engineer responsible for the remedial design and removal of the Parrot Tailings. Awarded by the Montana Natural Resource Damage Program (NRDP) in 2015, this project is a fully integrated remedial design, construction and disposal project requiring the full expertise of the WET team. Work has consisted of site investigation/characterization, tailings removal design, haul road design, repository siting design, evapotranspiration cover design, ground water dewatering design, utility relocation and replacement, end land use design, bid package preparation, and public/stakeholder coordination.  When complete, the Parrot project will include the removal of nearly 900,000 cubic yards of material, including: 260,000 cubic yards of waste material and 100,000 cubic yards of slag.