To remove fuel contaminants in the soil at 15.5 Mile Haines Highway, the Army Corps of Engineers proposed excavating at least 7,500 tons of soil as part of an interim soil removal action. The Army Corps is currently evaluating local landfarming as an alternative compared to shipping the soil to the Lower 48.
The Army Corps has proposed to use property near 24 Mile Haines Highway to landfarm the soil. That process involves spreading the soil into an 18-inch thick layer and promoting microbe growth that would remove the contaminants naturally, said Will Mangano, an Army Corp environmental engineer. During the estimated two years it would take to clean, engineers would plow and aerate the soil and take samples over time to ensure the contaminants are being removed and not moving deeper into the soil.
The contaminants resulted from a reported 33,000-gallon fuel leak in 1968 from the Haines-Fairbanks Pipeline. At the time, the pipeline was excavated and the fuel was burned off. In the 1980s, the federal government established a program to clean up sites no longer owned by the Department of Defense that were impacted by previous military operations. The Army Corps has been investigating and monitoring the site since 2012.
Last week, Army Corps staff detailed their proposed remediation project to residents in the Chilkat Center, many of whom expressed skepticism about transporting the soil to a remediation site near the river.
“It’s a preferable location because it’s not within town,” Mangano said. “It’s relatively industrial in nature. That area is basically a gravel pit.”
Fisherman Ryan Cook and Lynn Canal Conservation executive director Jessica Plachta were concerned about the location of the landfarming site, which is near a man-made salmon spawning channel connected to the Chilkat River that is considered anadromous habitat.
“Why put a landfarm at the head of a salmon spawning channel?” Cook asked.
Mangano said the site wasn’t the Army Corps’ first choice. Their preferred site was the old Army tank farm on Lutak Road, but they couldn’t come to an agreement with the landowner, Mangano said.
Beth Astley, Army Corps Alaska district project manager, told the CVN that the U.S. Army garrison at Fort Wainwright owns the property and they felt it was too risky to the Army’s environmental restoration goals at the Haines Fuel Terminal.
“The Haines Fuel Terminal is a contaminated site itself,” Astley said. “The Army has been working to clean up that site for many years so that the land can be released from Army control. They’re near the end of that process. They weren’t comfortable with landfarming because it might conflict with their clean-up activities and project schedule.”
The Army Corps plans to dig out contaminated soil from both sides of the highway, which would leave contaminated soil underneath the road. Tim McDonough asked why the Army Corps wouldn’t excavate the soil during the Haines Highway reconstruction project.
Mangano said the Alaska Department of Transportation’s work schedule doesn’t align with the Army Corps, and that removing soil underneath the road goes beyond the scope of the highway project. The Army Corps proposes using a combination of in-situ treatment techniques that would reduce the remaining contamination under the road. After the soil removal, an oxygen-releasing compound would be distributed into the soil to promote faster breakdown of the petroleum by microbes.
The second part of the in-situ treatment would involve injecting granular activated carbon into soil on the river side of the road to reduce the contamination in groundwater flowing toward the Chilkat River slough. Mangano explained that the natural removal of the material by microbes is already occurring at the site and these in-situ treatment methods would help the microbes break down the remaining petroleum contamination more quickly.
“Those two treatment methods in concert will help remediate the soil underneath the road,” Mangano said. “Will it remediate it as fast as just digging it up would? No. Dealing with the constraints, this is the preferred alternative.”
The Army Corps has been investigating the area since 2012. In 2014, engineers installed eight groundwater-monitoring wells and collected multiple sediment and surface water samples from the Chilkat River Slough with no contamination detected in the sediment or surface water.
In 2016 scientists first noticed a sheen within a groundwater seep on a gravel bar along the base of the river bank at low water. They sampled the groundwater seep, which tested positive for contaminants. In 2018 they sampled surface water from the Chilkat River Slough at five locations and none of the samples tested positive for contamination. In 2019, they again observed the sheen in a groundwater seep on the gravel bar at low water and a sample of the seep exceeded Alaska Department of Environmental Conservation standards.
Army Corps engineers believe that when the water levels rise in the spring and summer, the groundwater is pushed away from the slough within the project area, and flows back toward and into the slough during low water. “There is some point seasonally where this standing water interfaces with flowing water so there is some degree of likelihood of this ending up in the flowing slough.”
Mangano said the Army Corps wants to start excavating the soil by August, and will continue to monitor the site after the initial remediation effort.
The pipeline was constructed in the 1950s for U.S. military operations. The leak at the site is one of 20 along the pipeline, and one of 100 projects across the state being addressed by the Army Corps.
The plan is preliminary and the Army Corps is taking public comment on their preferred alternative.
The Army Corps environmental assessment can be found at http://www.poa.usace.army.mil/Library/Reports-and-Studies
Written comments can be emailed to [email protected] or mailed to ATTN: CEPOA-PM-ESP-FUDS (Astley), PO Box 6898, JBER, AK 99506. The deadline to submit comments is March 6, 2020.