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Harrison Road and Millmar Road Dross | Site Overview

Registry placement date: April 3, 2017

Score: 40

Location: Tucson, approximately bounded by Millmar Road to the north, Mountain View to the south, the private driveway of 9880 Millmar Road to the east and Harrison Hills wash to the west. The site is consists of mainly residential land uses.

If you own a private well, live in or near the site boundaries, and have not had your well tested, please contact ADEQ

Contaminants of concern: Aluminum dross is a byproduct of aluminum scrap meltdown and consists of a gray ash-like substance interspersed with metal pieces. Dross often contains heavy metals. The metals detected at this site over regulatory standards for soil are aluminum, antimony, arsenic, cadmium, copper, lead and nickel.

Action taken: Preliminary investigations in 2015 and 2016 indicated that the site contained heavy metals, including lead, above residential Soil Remediation Levels (rSRLs). Two distinct piles of dross were present: one large pile and a smaller pile mixed with soils next to the Harrison Hills Wash. Metals exceeding rSRLs were also detected in the Harrison Hills Wash, which discharges into the Pantano Wash less than 0.5 miles downstream. The investigations determined that groundwater in the area has not been contaminated by the dross present at the site.

In August 2016, an Early Response Action (ERA) was conducted to remove dross and contaminated surface soils located near a residence, remove the contamination from the wash and stabilize the nearby areas, and place a temporary cap over the disturbed areas.

After registry listing in April 2017, additional actions were taken to decrease the overall area of the large pile and design a permanent soil engineered cap for the site. Cleanup activities were completed within 180 days of the listing date.

The Remedial Investigation (RI) was finalized in December 2017. The Feasibility Study (FS) was issued in March 2018. The FS found that no further remedial actions were required for the site. Declarations of Environmental Use Restriction (DEURs) were placed on the deeds of the affected properties to prevent future exposure.

On September 10, 2019, ADEQ removed this site from the WQARF registry. After the cleanup and capping activities, the site does not pose a risk to human health or the environment.

Community involvement activities: ADEQ informed any property owners/tenants surrounding the pile area of the remedial actions and a public comment period related to the registry listing was announced. If you would like more information and/or want to be on the mailing list, please contact the community involvement coordinator.