The U.S. Army Corps of Engineers is resuming cleanup of soil contaminated by a fuel spill more than 50 years ago at 15.5 Mile Haines Highway.

The soil removal project began last spring but was put on hold in mid-June when surface water and groundwater levels rose enough to create an “unfavorable condition for continued excavation and backfill activities in low-lying and wetland environments,” according to an Army Corps report.

Ahtna, contracted by the Army Corps, resumed excavating on March 26.

More than 5,000 tons of contaminated soil were excavated last year, trucked to Lutak Dock and shipped to Juneau for remediation at a soil treatment facility and future disposal at the landfill.

The Army Corps said another 5,000 tons would be excavated this spring. Ahtna is removing soil and backfilling on both sides of the highway.

Field work is tentatively scheduled to end on April 28.

A 1968 leak in the now-decommissioned Haines-Fairbanks Pipeline caused the contamination. More than 33,000 gallons of jet fuel spilled from the 626-mile-long pipeline, which was used to transport fuel from the Lutak Tank Farm to military installations in Interior Alaska.

The Army Corps — which has been monitoring the site since 2006 and planning to address contamination since 2012 — discovered in 2019 that hydrocarbons in the soil and groundwater were leaching into a slough along the Chilkat River. A sheen in a groundwater seep, which tested positive for contaminants, was first detected in 2016, but tests in 2017 and 2018 showed decreasing pollution.

The Army Corps initially proposed remediating the contaminated soil at a landfarm at 24 Mile Haines Highway but ultimately, following public resistance to the idea and finding an opportunity to treat soil in Juneau, decided to barge it south.

The Army began operating the pipeline in 1956. Most of its 42 miles between Haines and the Canadian border are buried underground. “Constant leaks” in the pipeline occurred due to corrosion, the Army Corps reported. It was phased out between 1971 and 1979.

The cleanup project so far has cost $4.4 million.