SAHUARITA, Ariz. — The U.S. Army Corps of Engineers Los Angeles District began a remedial investigation and feasibility study July 13 at the former Sahuarita Air Force Range in Pima County, Arizona.
SAFR is a Formerly Used Defense Site of approximately 27,000 acres. Airmen from Davis-Monthan in Tucson used the site from 1943 to 1958 for bombing and gunnery training.
This RI/FS will investigate more than 10,000 acres using digital geophysical mapping.
"DGM is being used to characterize the nature and extent of munitions of explosive concern at the site," said Kyle Lindsay, a geophysicist from the Sacramento District. "DGM locates anomalies resulting from metal in the subsurface. These anomalies are then excavated to determine what they are, and the information is then used to define concentrated target areas which help determine an appropriate remedial action."
To calibrate the DGM equipment, three site survey control points were established for the area.
"A number of quality control tests are run at the beginning of each day to ensure the geophysical instrument is functioning properly," added Lindsay. "Additionally, data is collected over an area with known objects buried at known depths and locations to verify GPS accuracy and instrument readings."
In addition to the harsh desert terrain, some of the munitions used were quite small.
"The smaller an object is, the more difficult it is to accurately detect in the subsurface," said Lindsay. "There were some very small munitions potentially used at SAFR which presents an interesting challenge for DGM."
The District is working with the State of Arizona Department of Environmental Quality Federal Projects Team as a regulatory partner for the project.
"ADEQ's role is to provide oversight of the project and to ensure that all State and Federal regulatory requirements are properly followed and met," said Sara Benovic, ADEQ project manager. "We will coordinate with the Corps and all stakeholders to discuss the project by participating in Technical Project Planning meetings, teleconferences, site visits and emails."
The RI/FS will run through May 2018, with a final report due in August 2019.
"ADEQ appreciates being a part of this project and looks forward to working with the Corps, as well as stakeholders such as Arizona State Land Department and the City of Tucson," added Benovic. "Our mission is to protect and enhance human health and the environment."