Plan eyes leaking dozer at Higgens Point

COEUR ALENE — A containment system to capture any oil leaking from sunken construction equipment at Higgens Point is expected to be completed by this summer.

Associated Underwater Services of Spokane is drawing up plans for a stainless steel hood that will encase a D-9 dozer, which is buried in rock under about 90 feet of water.

“We are committed to protecting the lake, which likely includes several more years of monitoring and maintaining the hood,” Emergency Response Coordinator Chris Williams said.

The 40-by-40-foot hood will be built on the shore of the lake and could be in place as early as June.

“That’s a lot of stainless steel, and getting our hands on that material will be a challenge," Williams said.

Other options, like removal of the equipment, were considered with agencies like the Idaho Department of Environmental Quality "but dismissed due to the risk of affecting the rockslide area and the potential harm to staff and the environment," a press release said.

The source of the oil was identified as the dozer that fell in the lake during Interstate 90 construction in 1990. A Caterpillar 631 scraper also went in.

The tank of the scraper was drained, but the dozer was inaccessible, according to ITD.

"State and federal agencies agreed that retrieval methods were too risky — both in terms of risk to personnel and to the stability of the slope underwater — and decided to abandon the equipment," ITD said.

A first oil leak was reported in 2000.

In 2001, a stainless steel hood was built and installed to capture any releases in a canister that could be emptied by divers. In 2002, a protective membrane was added to partially cover the dozer and further funnel product into the hood, ITD said.

Another leak in 2010 led to the removal of the hood, which was replaced with a larger membrane and a catchment system to receive and absorb any product.

There were no more leaks until early December, when ITD was notified of product coming to the surface in the general vicinity of the relic equipment.

Oil sheens stretched from the site toward the shoreline.

The agency placed floating booms to both contain the diesel leak from the dozer and protect the shoreline, according to ITD.

"Dives determined that the equipment was still buried, but that the older, first protective membrane had been disturbed, likely after being caught by a boat anchor," according to ITD. "The other membrane looked to be intact."

Both membranes will be removed, and the hood will be built large enough to completely cover the buried dozer. Fluids will be trapped in the hood, which will have a containment vessel to monitor and empty when needed, ITD said.

ITD contracted with Associated Underwater Services to design and build the hood for about $250,000.

The hood is similar to previous containment systems, which also used protective membranes to funnel any escaping fluids to a device where it could be emptied and replaced.