Channel depths won’t be dredged

Coeur d’Alene developer Duane Hagadone no longer plans to dredge the deepest part of the Blackwell Island channel, acknowledging the potential for releasing heavy metals into Lake Coeur d’Alene and the Spokane River.

Instead, Marina Yacht Club LLC reconfigured the location of the proposed boat slips to avoid dredging in the open water at the mouth of the Blackwell Island channel, near Cedars Restaurant.

After working out a land swap with John Stone, who owns the neighboring waterfront, Hagadone now has the ability to build boat slips on the opposite side of the channel mouth where it’s naturally deeper.

The area is where Foss Maritime once stored logs.

The new design also would allow the company to add 50 boat slips for a total of 419 leased slips plus room for 146 jet skis.

This reworking is illustrated in a revised permit application to the U.S. Army Corps of Engineers for the multimillion-dollar marina upgrade at the mouth of the Spokane River. The manmade island is bisected by U.S. Highway 95 as it crosses the river.

“We’ve made some major modifications to the project to try to fit within and work around their concerns, and I think we’ve done that,” said engineer Jim Coleman, referring to the various state and federal permitting agencies that feared the dredging would harm water quality.

The Army Corps and the Idaho Department of Environmental Quality haven’t yet fully reviewed the revised application.

“We haven’t gotten a chance to get our heads together to go over but that’s the next step,” said Gregg Rayner of the Army Corps.

The marina company still plans to remove dirt from the remainder of the channel, making it about 50 percent wider and at least 8 feet deep to allow for bigger boats.

But Coleman said all that excavation will take place in the dry – meaning workers would use dams to keep out the water and decrease the chance of releasing heavy metals into the water.

The change will reduce by about 40,000 cubic yards the amount of sand, silt and gravel removed from the channel, Coleman said. Initially the proposal was to excavate up to 220,500 cubic yards.

Soil tests from the channel show elevated levels of heavy metals, particularly zinc and cadmium, that can dissolve in water.

Because the company now plans to do all the excavation in the dry, Coleman said it’s possible to haul those contaminated soils – perhaps 26,000 cubic yards – to a disposal site.

The company is looking at about five locations but won’t make a final decision until the corps issues the permit, Coleman said.

Permits also are needed for the disposal area, and Coleman assumes that would become a condition of the corps’ approval.

The disposal areas would have underlying soils that are clay and rock, which would prevent any metals from leaching into the groundwater. The application states that no sites are over the Spokane Valley/Rathdrum Prairie Aquifer or within recharge areas, and they are at least 300 feet from a water body.

The decision to transport the contaminated soils came after the corps ruled last year that about 2 feet to 4 feet of surface material isn’t suitable for disposal where it could leach into the lake or river.

It’s unknown if the agency will request a public hearing before deciding whether to issue the company a permit. The DEQ must also provide water quality certification.

Once that’s done, Marina Yacht Club will resubmit its proposal to the Idaho Department of Lands for approval. Hagadone withdrew his application with the lands department in August, opting to wait for a decision by the corps and DEQ.

The decision delayed the marina expansion by at least a year.

The withdrawal came after the lands department denied Hagadone’s dredging request in July, saying it didn’t have adequate information from the corps and DEQ.

Coleman said the company hopes excavation work can begin this fall.

It’s possible the company will start construction of the seawall at the north end of the channel this spring.

Coleman said because the seawall is above the high-water mark and wouldn’t affect the lake or river, no permits are needed.