Preliminary soil samples show that sediment in the Blackwell Island channel may have lead levels high enough to require the dirt to be capped so it’s not ingested by children or used for gardening.
Yet more extensive tests are needed to determine if unsafe levels of hazardous materials that could harm human, wild and aquatic life are present.
Marina Yacht Club LLC, which is owned by Duane Hagadone, wants to dredge the Blackwell Channel, making it wider and deeper as part of a planned marina expansion. The proposed dredging area is from Lake Coeur d’Alene downstream, past the marina, to where the channel flows under U.S. Highway 95.
Hagadone Corporation hired Esvelt Environmental Engineering of Spokane to sample four areas of the Blackwell Channel in February. The test results were included with permit applications submitted this month to the Idaho Department of Lands and U.S. Army Corps of Engineers.
Owner Larry Esvelt said Friday that the samples, which were tested for lead, cadmium and zinc, don’t pose a “significant indication of concern.”
Yet Idaho Department of Environmental Quality officials say the samples didn’t include tests for arsenic, mercury, silver, barium, selenium and chromium. The state also requires other tests that would determine the effects of dredging not only on humans, but also aquatic life and wildlife. Dredging could stir up heavy metals in the soil, causing them to dissolve and pollute the water.
“A lot more testing needs to happen,” said June Bergquist, a DEQ water quality compliance officer. “This is a great start, but we need to do more samples and different kinds of sampling.”
The Esvelt tests show that lead levels in the soil are 40 to 90 times the allowable amount but remain below federal toxic waste standards. According to Esvelt’s report, that means that the sediment wouldn’t have to be shipped to a hazardous waste site but that isolating the dirt so it’s not disturbed is recommended if it’s used as fill.
“It would be prudent to dispose of the material such that children would not be in a position to ingest the soil where normal usage would include growing vegetables or fruit for human consumption,” Esvelt wrote in a March 23 memo to John Barlow of Hagadone Corporation.
Hagadone proposes using the soil to fill parts of Blackwell Island. The plan is to remove about 220,000 cubic yards of sand, silt and gravel from the channel, making it about 50 percent wider and at least 8 feet deep to accommodate larger boats. The marina wants to start work by Nov. 15.
Esvelt said he only tested for the three metals that are of the highest health risk because of mining’s legacy in the Silver Valley and Coeur d’Alene River Basin. Agencies also have concerns because Blackwell Island was once a city-run landfill and there are questions about whether dredging could damage the seal over the Spokane Valley/Rathdrum Prairie Aquifer, which is the sole source of drinking water for 400,000 people.
Esvelt said he’s not surprised that the agencies want more testing. When Hagadone hired him last winter, he said it was unknown what the company planned to do with the newly purchased property. So that’s why Esvelt didn’t talk to the state and federal agencies about what tests were needed for a dredging project.
“We were looking for things that would say ‘Oops, we don’t want to buy this,’ ” Esvelt said. “The risk is reasonably low but there’s no guarantee.”
Barlow wasn’t available for comment but told the Coeur d’Alene Press, which is owned by Hagadone, that the soil has been tested and heavy metals aren’t an issue.
Yet an Idaho Department of Environmental Quality official says that’s not accurate.
“It’s partially true,” Bergquist said. “They did test for some of the metals and they were below the action levels for that set of laws.”
She said the tests need to include a wider variety of metals, and other laws must be considered, such as Idaho’s standards for dredging. Berquist said it’s impossible to compare Esvelt’s tests with the standards that DEQ follows.
Hagadone bought 38 acres of Blackwell Island in January for an undisclosed amount from brothers Robert and Mark Hall.