The Pinal Creek Group has completed construction of the Lower Pinal Creek barrier wall for capture and containment of affected groundwater. The three-foot thick wall is approximately 1,200 feet long and reaches about 100 feet deep. It was constructed by the slurry trench method, using a low permeability soil-cement-bentonite clay mixture.
Pinal Creek Group Installs Barrier Wall and Wellfield
The Pinal Creek Group has completed two important projects designed to protect surface water in perennial Pinal Creek. The Lower Pinal Creek Barrier Wall And Wellfield will control downstream movement of affected water and serve to improve the capture effectiveness of the wellfield by intercepting and damming up groundwater to allow for pumping at the wellfield.
The barrier wall is approximately 1,200 feet long and reaches depths of about 100 feet. The three-foot thick wall was constructed by the slurry trench method, using a low permeability soil-cement-bentonite clay mixture.
The wellfield consists of extraction wells, and several upstream and downstream monitoring wells.
The arrangement and number of the wells completed within the wellfield was based on the vertical and lateral distribution of metal concentrations in the alluvial (shallow) aquifer. The arrangement of the wellfield also was based on a numerical modeling analysis of the capture zones created by various alternative well arrays. The monitoring wells were installed, to monitor the capture zone created by the wellfield.
The barrier wall and wellfield allow capture and pumping of affected water to the Lower Pinal Creek treatment plant, which neutralizes water and removes metals to reduce concentrations within Lower Pinal Creek where year-round surface flow occurs. This also will result in a reduction of overall loading of metals and acidity to perennial Pinal Creek.