Denver: Heron Pond redevelopment poses environmental challenges

Proposed Heron Pond Park via the City of Denver.

Click here to read the master plan.

From The Denver Post (Bruce Finley):

The 2-foot-deep pond holds toxic sludge laced with lead, arsenic and cadmium. Contaminated stormwater runoff from surrounding work yards worsens the brew…

Denver’s willingness to embrace such a site for future parkland reflects the increasingly difficult challenge of establishing enough public green space to keep pace with population growth and development. Denver has fallen behind other U.S. cities in urban parks and open space. This is causing discomfort, hurting public health, exacerbating heat waves and risking costly problems with stormwater runoff.

City officials interviewed by The Denver Post said they see establishing new green space as essential but, perhaps, impossible given the rising price of land. Yet voters recently ordered a sales-tax hike that will raise $45 million a year for parks and open space. This has compelled planners to pore over thousands of acres that could be preserved as green space.

The problem, city officials said, is competing with private developers for land. Developers since 1998 have installed buildings, paved over natural terrain and otherwise overhauled vast tracts of the city — profiting from shopping plazas and upmarket apartments that eventually sell as condominiums. They’ve built higher, lot-line-to-lot-line in some areas, leaving less space to even plant trees.

Turning to marginal industrial land, city officials said, may be Denver’s best hope for stabilizing a decline in green space per capita.

Chief parks planner Mark Tabor said that, after establishing the new green space around Heron Pond, Denver officials could try to purchase the land around the Arapaho power plant south of downtown and in the rail yards northwest of downtown for preservation as large green space where natural ecosystems could be restored.

This approach hinges on cleanup.

It can be done, not just by excavating and hauling away contaminated soil but by using modern cleanup methods that remove acidity and toxic metals, said Fonda Apostopoulos, a Colorado Department of Public Health and Environment engineer who managed decontamination of the Asarco smelters and 862 residential properties near Heron Pond.

“The low-lying fruit of clean property in Denver is few and far between. ‘Brownfields’ are pretty much the only property people are developing,” Apostopoulos said.

“It is all about exposure pathways” — the ways contamination can reach people, he said.

Around Heron Pond, cleanup included excavation and replacement of soil around homes. Nine new monitoring wells will be installed between the smelter site and the South Platte River to make sure toxic metals no longer contaminate groundwater, Apostopoulos said, pronouncing the area safe for at least passive recreational activity.

While cleaning up industrial wasteland costs hundreds of millions of dollars, “there are a lot of private-public partnerships that could do that,” he said. “Denver could get extra federal funding. They could get cleanup grants.”

Proposed Heron Pond boundary via the City of Denver.

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