As a kid, Gary Snodgrass played ball near the willow trees and dug for earth worms in a now fenced-off swath of land abutting Middle Twin Lake in Brooklyn Center. Growing up, he never thought twice about the splotchy black stains on the rocks and soil underfoot.

Not until years later did Snodgrass discover that the wooded green space where he once played was part of a larger site that decades of wood-treating operations had left polluted.

More than a decade after most of the Superfund site has already been scrubbed and redeveloped, pollution officials are now tackling the remaining 11 or so acres on the site's western edge and fielding feedback from residents about a proposed $4.8 million cleanup plan.

"I figured most of it was already cleaned up," said Snodgrass, 59. "Why didn't they do all of it when they cleaned up the rest?"

State pollution officials say the delay in addressing this remaining parcel partly stems from the Superfund program being in "triage mode," with limited staffing and a growing workload.

Cleanup efforts at the Brooklyn Center site date to the 1980s. Joslyn Manufacturing & Supply Co. was named responsible to work with the Minnesota Pollution Control Agency (MPCA) on a cleanup in 1983. The area made the federal Superfund list in 1984.

From the 1920s until 1980, companies at the site treated materials like wooden utility poles and railroad ties with preservatives, which polluted the soil and groundwater with pentachlorophenol (PCP) and other contaminants. Over the years, cleanup has included treating and disposing of contaminated soil and extracting pollutants from the aquifer. Pumps continue to remove contaminated groundwater on the site, which has been largely redeveloped with new buildings and businesses.

City officials say the remaining swath, which is still owned by Joslyn, is wet, marshy land ill suited for development even when it's been cleaned up. Even so, they said they welcome remediation.

"It's been long in the coming," said City Engineer Steve Lillehaug.

Pollution and health officials say a driving force behind the latest cleanup effort is dioxins, a contaminant first discovered in the western portion of the site in 1998. Dioxins can cause cancer, as well as reproductive and developmental problems, among other health risks.

Health officials say residents may have come in contact with contaminants by walking or biking through the wooded area. But, they said, that area is removed from the most polluted areas, making health effects unlikely. Testing also shows that the site has not had "an adverse impact" on the lake, according to the health department and MPCA.

But residents say they still worry about their years of potential exposure.

Rick Arntson, 67, has lived in the neighborhood since the 1970s and used to bike with his kids through the green space. He always noticed an oily smell, but it wasn't until a fence blocked off the worn walking path about 15 years ago that he got nervous.

"I wonder what kind of stuff I came in contact with," said Arntson, a retired carpenter. "If it was bad for us, what took so long to put that fence in?"

Several dozen residents turned out to a public meeting Wednesday to hear the MPCA's pitch for remedying the remaining green space just east of Middle Twin Lake. Residents have until May 19 to submit feedback.

The pollution agency is proposing a plan that includes digging up contaminated soil and hauling thousands of truckloads of it away to a landfill. The remaining polluted soil will be consolidated in a mound and capped with at least 2 feet of clean soil.

"This is the final chapter in the cleanup story of this property," said Hans Neve, who supervises the Superfund program at the MPCA. "It's overdue."