Once contaminated, ground water is difficult, and sometimes, impossible to return to its original quality. Restoration of ground water often takes decades to accomplish and can be very expensive. Cleanup timeframes typically are measured in years or decades.
The DEQ-WQP has been involved in a number of groundwater investigations and cleanup projects in the Community. The largest to date is the North Central site.
NORTH CENTRAL SITE
In January of 2000 the Gila Floodway groundwater monitor well was installed approximately one-half mile west of the intersection of I-10 and the Wild Horse Pass Road. The Gila Floodway well was screened from 70 to 90 feet below the ground surface with the intention of monitoring ambient background water quality in the subsurface beneath the Gila Floodway. During subsequent sampling events a common man-made chemical trichloroethene (TCE) was consistently detected in the groundwater samples. TCE, a solvent, is commonly used to remove grease from metal parts in commercial applications and to clean electronic circuit boards. If TCE is leaked onto the ground, it can move downwards through the soil and eventually come in contact with the groundwater.
Based on the results of the groundwater sampling, an investigation was initiated to determine the source of the contamination and mitigate the potential impact to groundwater. The DEQ-WQP installed and sampled a series of groundwater monitoring wells to investigate the site hydrogeologic setting and the distribution of contaminants. The water quality data collected from the groundwater monitoring wells demonstrated that the plume of groundwater contamination included 1,1-dichloroethene (1,1-DCE), tetrachloroethene (PCE), 1,4-dioxane and perchlorate, among others.
It appears that the contamination likely occurred in the early 1980’s from two industrial facilities.
At this time, drinking water wells in the area of the TCE contamination have been tested and do not contain TCE or other contaminants above the EPA public health standards.
The DEQ, with assistance from the US EPA have been overseeing the groundwater investigation and cleanup efforts.