Klondyke Tailings Project

Klondyke Tailings Project

Registry placement date: Sept. 28, 1998

Score: 69

County: Graham

Location: Two miles north of the town of Klondyke in Section 6, Township 7 South, Range 20 East with boundaries defined by the extent of soil contamination above the residential soil remediation level (SRL) for lead of 400 milligrams per kilogram (mg/kg). The site boundary is irregular and includes the property containing the tailings piles and several surrounding properties.

Contaminants of concern: Antimony, arsenic, cadmium, copper, lead, manganese, mercury and zinc

Action taken: Sampling to determine the extent of off-site soil contamination began in 2006. To date, approximately 2,500 soil samples have been collected from the site and adjacent properties. The limits of the 400 mg/kg residential soil remediation level for lead have been defined to extend approximately a half-mile from the site and impact nine adjacent properties.

Early response action (ERA) activities continue at the site. These activities have included geophysical surveys and minor repairs to the berms on the tailings piles. Aerial photography, topographic mapping, historic aerial photography analysis, floodplain delineation and analysis of the 10-, 25-, 50- and 100-year floodplains and a geomorphology study of Aravaipa and Laurel Creeks were done to evaluate possible remedies due to the site’s location near these creeks.

ADEQ selected gabion mattresses for erosion protection in October 2007. Erosion protection installation began in March 2008. In June 2008, erosion protection installation was completed on the upper tailings pile and the clean soil cap was seeded.

ADEQ, with the Environmental Protection Agency’s (EPA’s) assistance, evaluated soil removal options on the residential properties located in the vicinity of the site. EPA collected additional samples in the immediate area surrounding five residences in March 2010. In the 2012 fiscal year, the EPA initiated the planned removal of contaminated soils from three properties.

During June 2012, approximately 2,000 cubic yards of contaminated soil were removed from two of the properties. An additional 1,040 cubic yards of contaminated soil was removed for one of the original properties and the third property in October 2013.

Status: In 2014, the final remedial investigation (RI) was completed. 

Community Advisory Board (CAB): Established and meets on a regular basis