Another 7,000 acres of old arsenal cleaned

Ann Imse, Rocky Mountain News

Tuesday, December 20, 2005

The Army and the Shell oil company have completed cleanup of another 7,000 acres of the Rocky Mountain Arsenal, the former chemical- weapons and pesticide plant northeast of Denver.

Officials expect that by spring they will begin the process of removing this land from the Superfund list and adding it to the existing 5,000- acre wildlife refuge on the site.

After the transfer, expected by autumn, the wildlife area will cover most of the Manhattan-size arsenal site, excluding 4,000 acres at the center that once contained more than 200 chemical-industrial buildings.

This was the most contaminated section, and cleanup will take another five to six years, said Charley Scharmann, the Army's civilian project manager.

Another 1,000 acres along Quebec Street was sold to Commerce City in 2003 for a commercial and soccer- stadium development.

Cleanup of the latest 7,000 acres at the arsenal, located north of the former Stapleton Airport and west of Buckley Road, is a second enormous milestone for the Denver area environment this year.

The demolition and cleanup of the 6,000-acre, 300-building Rocky Flats nuclear-weapons plant south of Boulder was certified complete this month.

The arsenal contaminated groundwater on and off its site with components of sarin nerve gas, mustard gas, pesticides and solvents.

Today, five treatment plants are gradually cleaning up that contaminated water, and all nearby homes on well water have switched to municipal water piped in from elsewhere.

About 3,000 monitoring wells track the remaining contamination, he said.

The arsenal, eight miles from downtown Denver, opened during World War II to make mustard gas. It produced sarin nerve gas in the 1950s and napalm in the 1960s, and was used to deactivate such weapons in the 1980s. And Shell made pesticides, some of them later banned.

The first 5,000 acres became a wildlife refuge last year, but access is limited. Visitors are allowed in educational groups during the week, and on 10 miles of trails on weekends, supervising Ranger Sherry James said. Catch-and-release fishing is permitted in two lakes, but mercury levels are too high for the catch to be eaten.

A herd of about 750 deer share the grasslands with coyotes.

The new 7,000 acres will add the northern shores of three lakes to the official refuge, including groves of cottonwood trees that are home to 30 to 40 bald eagles, James said.

A pesticide showed up in the brain of nearly every dead small bird tested 10 to 15 years ago, but that has dropped significantly, James said. Contamination still shows up sometimes in small birds and burrowing animals such as mice and prairie dogs, James said.

She said she is thrilled to have such a large wildlife habitat in an urban area.

"This is a great opportunity for kids from inner-city schools to see wildlife. We're 10 minutes from Denver," she said Monday, while pointing out numerous eagles and dozens of deer in shafts of fading winter sunlight.

And if it didn't start out clean, "Hopefully, we can convert it into pristine land," she said.

In the central section that is still being cleaned, trucks haul toxic waste to a double-lined landfill, and they will soon start filling a triple-lined landfill with even more dangerous poisons, Scharmann said.

When they are full, they will be covered with 18 inches of concrete in 4- to 12-inch chunks, and 4 feet of soil, he said. Such covers were tested and found to keep rainwater from seeping through, he said.

Other large sections of the industrial area where chemicals were dumped or spilled also will be given such caps, he said.

Just to the south of the arsenal are hills of concrete and asphalt from ripped-up runways at the old airport. The arsenal plans to buy 2 million tons of it for use in capping its pollution.