Originally Published: April 28, 2010 9:55 p.m.
DEWEY-HUMBOLDT - Now that a federal agency has completed its investigation of contaminants at the Iron King Mine and Humboldt smelter sites here, its next task is to decide how to clean it up.
About 50 people attended a community meeting Tuesday night at Dewey-Humboldt's American Legion Post No. 78 where the Environmental Protection Agency reported its findings on the Superfund hazardous waste cleanup sites and again offered residents the chance to get their residential yards tested for toxic arsenic and lead.
This past year, EPA officials tested 65 parcels on the sites and found that these contaminants more often affected yards closer to the mine's tailings pile and the smelter's ash/slag pile than spots farther away.
Although the EPA says that the maximum levels of contaminants found on the sites will not cause acute health problems in humans, officials are concerned about long-term exposure and the potential cancer risk.
As for the sites' cleanup, EPA remedial project manager Leah Butler said it could include anything from "doing nothing to removing everything from the site and all options in between."
"It's too early to say what will be done," she said. "It's likely that the cleanup will involve a combination of consolidating, capping and removal (of contaminants from the mine and smelter)."
Butler would not comment about who is on the EPA's list of potentially responsible parties for the contamination. The EPA is forming the list now, which remains confidential until the cleanup option is approved within the next year.
"Once we decide the cleanup option, we will negotiate with the responsible parties about how to pay for or conduct the cleanup under an agreement with the EPA," she said. "If those parties are not able to pay, the EPA will do the work, pursue the costs incurred and settle with them."
On Tuesday, residents who live near the mine and smelter sites could sign up for free, voluntary soils testing, which the EPA will conduct from May 2-14 to help folks determine if they have elevated levels of arsenic or lead on their properties.
"There is no way of knowing what each yard's soil has (as far as its chemical make-up)," Butler said.
EPA officials also will offer free sampling of residents' private wells from May 6-13 in which they look for elevated levels of chloride and sulfate, a pair of commonly found chemicals on the sites, in the groundwater.
In addition, on Monday, a team with the University of Arizona Superfund Research Program announced that it broke ground on a project designed to plant vegetation (potentially buffalo grass, mesquite, quailbush, etc.) with varying amounts of compost on the mine's tailings pile.
Raina Maier, associate director of the program, said the plants could reduce wind and water erosion, which move the tailings' contaminants into the environment.
On high-wind days, particularly in March, April, July and August, large volumes of dust from the pile kick up into the air and travel short distances. UA officials say they want to quantify and reduce those emissions.
During an 11-month period this past year, the EPA collected data from 10 air-monitoring stations across the site. Some showed elevated levels of arsenic and lead in the dust, which generally travels in a southwesterly direction.
Butler added that past breaches in the mine's tailings pile and the smelter's ash pile contributed to moving contaminants into the town. Tailings material has gone into the nearby Chaparral Gulch because of dam failures, thus hindering plant growth there.
As for the groundwater at the sites, the EPA found elevated levels of sulfate and chloride. Of the 67 private wells tested, five exceeded the feds' secondary drinking water standard for sulfate, while three others had elevated levels of chloride.
Butler said EPA officials will conduct more sulfate sampling to the east and north of the smelter. Even though sulfate has no ties to cancer in humans, it can have a diuretic effect.
Those officials added that they think the chloride may be tied to chemicals miners used in the early- to mid-20th century in smelting ore. Therefore, the EPA would like to test more private wells in the area.
The EPA encourages residents on private wells to get their water tested for free. If necessary, the agency will make water treatment options available.
Butler said Humboldt Water Co., the only municipal water supplier in Dewey-Humboldt, recently had one of its wells treated for arsenic to meet the feds' drinking water standard.
For more information about the EPA's project here, call EPA community involvement coordinator David Cooper toll-free at 800-231-3075 or e-mail him at firstname.lastname@example.org.
Those with questions or comments about the EPA's report should call Butler at 415-972-3199 or e-mail her at email@example.com.