SANDPOINT — The Idaho Department of Environmental Quality plans to begin analyzing materials used to improve a road into a proposed housing development after concerns were raised about heavy metal contamination.

Regulators are scheduled to conduct the testing this week using X-ray fluorescence spectrometry, said Rob Eachon, an environmental compliance officer with DEQ in Coeur d’Alene. The portable XRF device bombards a sample with X-rays to determine the elemental composition.

Eachon said the testing will be done on-site and if metals are detected via XRF, samples will be obtained for more thorough testing in a lab.

“Every 15th reading we do with the XRF, we’ll also do a sample that’s suitable for lab analysis. But if we don’t get the initial hits or indicators that warrant lab sampling, we probably won’t do a lab sample,” he said.

The composition of the road material was called into question by opponents of the Ledges Over Pend Oreille, a proposed 33-lot subdivision at Morton Slough.

Members of Morton Slough Matters, a group which formed to challenge the development, said they obtained a sample from a public portion of the road leading into the project. The group’s co-founder, Ken Larson, said the material was analyzed in a private Coeur d’Alene lab, which indicated that the sample contained seven times the maximum allowable level of lead. Elevated levels of zinc were also detected.

“We had it analyzed by an EPA-certified lab so it was done with the proper testing methods,” Larson said earlier this week.

The group then forwarded its findings to DEQ.

“When we get a complaint, we take it very seriously,” Eachon said.

Opponents suspect the material used to improve the road came from a former mine site in the Talache area.

Ledges developer Rich Curtis is dubious of the contamination claims. He said on Tuesday the material was purchased from local sources and if it was tainted, he was unaware of it.

“It’s the same material, that we’re aware of, that the Idaho department of transportation uses as well,” he said.

If the rock is found to be contaminated, it would have to be removed and impounded to keep it out of the ecosystem and away from people, Eachon said.