A popular tourist stop in southeast Alaska is the Sitka National Historic Landmark on Baranof Island. Once a bustling military complex built to protect the lower 48 states from possible attack during World War II, the site closed at the end of the war and much was left behind.
The Alaska District of the U.S. Army Corps of Engineers (USACE) recently contracted with Ahtna Engineering Services to address decades of neglect on a series of islands all located off Sitka’s rocky coast. The work: to excavate, transport, and dispose of contaminated soil from Nevski, Rashimosti, Sasedni, and Makhnati Islands; and to excavate, transport, and dispose of contaminated soil and debris from the former landfill on Virublennoi Island.
A STRATEGIC LOCATION
In 1937, the first air station in the Alaska Territory was built by the U.S. Navy on Japonski Island, across from the City and Borough of Sitka. In undertaking the massive project, construction crews blasted from the surrounding mountains, leveled nearby islands, and methodically dumped dirt, gravel, and boulders into the ocean to create a series of causeways between Japonski Island and Sitka.
To protect the base, in 1940, construction began on Fort Ray, the Army’s first World War II facility authorized in the Alaska Territory, and located directly adjacent to the air station. The military continued to expand its defenses, constructing 8,100-ft of causeways connecting seven more islands, and incorporated the whole area into the Sitka Harbor Defense Complex. Tremendously ambitious for its time, construction included state-of-the-art gun emplacements, observation towers, command posts, personnel shelters, artillery magazines, fuse houses, motor sheds, officers’ quarters, storehouses, barracks, dayrooms, and mess halls. The three-gun batteries were considered bomb proof (built with 3-ft of reinforced concrete covered by 6-ft of earth) and designed to hold off mustard gas and other chemical weapons. Completed in 1943, Fort Rousseau on Makhnati Island became the headquarters of the harbor defenses of Sitka, with almost 8,000 troops assigned.
Toward the end of the war, when the Japanese threat to Alaska and the U.S. mainland had subsided, the harbor defenses were deactivated and abandoned. Fort Rousseau became a National Historic Landmark on Aug. 11, 1986, and in April 2008, it was also designated an Alaska State Historical Park.
Since its abandonment, however, powerful ocean storms and natural decay have damaged the causeways, rendering large sections unusable. Many of the islands in the park can only be accessed by boat. Unfortunately, many of the buildings and equipment left behind collapsed, deteriorated, or were removed, leaving large areas of soil contamination.
The remediation of Fort Rousseau Causeway State Historical Park would prove to be a logistical challenge from many angles. The first issue was how to access the project sites. The easiest access to the islands crosses what is now the only active runway in Sitka. That runway could not be closed, and a road could not be made around it.
With no road access, Ahtna used a landing craft to bring in equipment, gravel, supplies, staff, and everything needed to be self-sufficient while operating on site. To facilitate demobilization, a barge was anchored directly to a causeway and wastes were loaded directly to the barge.
Due to rough ocean currents, the team was only able to access Makhnati Island four times during the entire project.
There were quite a few places throughout the islands where batteries had been left, disintegrated, and impacted the soil with lead contamination. In many cases, some had already been picked up, but the team was tasked to clean up the soil.
Removing the lead-impacted soils was straightforward. The hard part was the removal action at the Virublennoi Island landfill.
Located directly on the shoreline, the landfill was eroding into the ocean and consisted of a mixture of soils, burned debris (potential dioxins), polychlorinated biphenyl-contaminated soil, asbestos, and lead from building debris and broken lead acid batteries. In particular, the contaminated landfill extended to sea level and below depending on the tides. The team had to come up with a way of holding back the ocean. Since there was no way to waterproof the excavation site, a temporary seawall was constructed out of large gravel filled “super sacks.”
Ultimately, a 6-ft tall wall, wrapped in a layer of plastic, helped reduce wave action. The project was intentionally scheduled to coincide with the lowest tide cycle of the year in order to remove contamination that was normally underwater. There was a window of only two days where tides were low enough to dig, otherwise the team might not be able to try again for six months to a year.
With the seawall in place, most of the contaminated material was able to be removed from below the sea level. The team removed materials down to bedrock, scraping and cleaning between the rocks and the boulders.
DISPOSING OF WASTE
Approximately 5,700-T of soil and debris was taken out of the landfill and placed in 9-yd3 bags. It took more than three days to load the material, which was ultimately barged to Seattle and then transported to Oregon for final disposal.
Upon analysis, there were many different types of contamination present, and questions to be answered for processing it safely. First, the waste had to be sampled to determine how to categorize it. What if the waste had polychlorinated biphenyls, dioxins, asbestos, or lead? Which supersedes the other? Was it considered hazardous waste? Ahtna went through and categorized all of it, and used a decision tree to designate each kind of waste.
FORGING A NEW LEGACY
There were unique aspects of the work because the entire area was a state historical park. Axles, vehicle parts, and other metal and concrete pieces were right where the troops left them decades before, in the hills, the woods, and on the beach. Was the team to pick up those pieces or leave them? The crew ultimately removed the soil under and around the items, then left them back in their original locations to preserve the history of the site.
At the end of the project, Ahtna left the trails in equal or better condition than before. Many areas were made more accessible to park visitors with disabilities. Originally, the boat landings were piles of rocks against the water. Because the project required accessibility for barges and landing craft, the team substantially upgraded several beaches. Sightseers can now land their kayaks at these locations and more easily access the bunkers and other buildings.
Local residents welcomed the project and appreciated the removal of the contamination. The work was completed early in the tourist season, minimizing conflicts. The community now has a clean, safe park to experience the passage of history.