The city has proposed a new use for the contaminated soil removed several years ago from the Riverbend Elementary School construction site.
The plan is to use the soil in berms at the Hank Harmon Rifle Range, city Lands Manager Steve Gilbertson said.
``We were looking to try and make a beneficial use of the material,'' Gilbertson said. ``It's a fairly large volume.''
The state Department of Environmental Conservation has given ``conceptual approval'' to the plan, said environmental specialist Sally Schlichting, ``but there's still a lot of things that need to be worked out.''
The U.S. Army Corps of Engineers needs to approve a permit for the plan, because it involves putting fill in wetlands.
Randal Vigil, a regulatory specialist with the Corps, said he's received several comments expressing concerns about the plan, including a letter from the state Department of Fish and Game questioning whether in the long term it could result in contamination to Montana Creek.
The soil is contaminated with petroleum products, but Schlichting said the contamination is at a low level. It is currently being stored on private property near the Montana Creek subdivision, Gilbertson said.
The city's plan for the soil's final resting place is the rifle range.
``We actually feel like the plan is pretty sound,'' Schlichting said.
The soil would be used in building target berms and safety berms, Gilbertson said. A safety berm is a mound that would prevent bullets from going to the pistol range from the rifle range and vice versa. Target berms are mounds holding targets.
Estimates of the amount of contaminated soil involved vary, but the Corps permit refers to 14,250 cubic yards being used in the berms. The plan is to place the soil on top of an impermeable liner, then cover the sides and top with 6 inches or more of glacial till.
The current plan is to require testing of the nearby surface water twice a year for two years, although additional requirements may be added, Schlichting said.
The Corps permit comment period ends today, although the agency will not refuse late comments, Vigil said.
The state Department of Fish and Game expressed concern about whether in the long run the berms would withstand the frequent impact from bullets, and if not, whether contamination would make its way into Montana Creek or its tributaries.
``There are small tributaries within a few feet of some of the berms,'' said Catherine Pohl, a habitat biologist with Fish and Game. ``It doesn't seem like the best place to try this thing out, so we have some concerns and are kind of awaiting more information.''
The U.S. Fish and Wildlife Service's initial letter to the Corps expressed no concerns, but agency staff have said they will be sending another letter superseding that one, Vigil said.
The Corps has also received nine comments from the general public on the proposal, eight of those opposed to it and one in favor, Vigil said. He did not know when a decision would be made.
Gilbertson said the city had hoped to do the project this summer.
Riverbend Properties, the partnership that sold the Riverbend school land to the city, is to pay for the permits, design and installation of the berms, Gilbertson said. The arrangement is part of a settlement of a lawsuit over the sale of the contaminated land.