Contractor is filtering groundwater at site after contaminant discovery
The discovery of high levels of manganese in groundwater encountered during digging at Denver’s City Park Golf Course for a drainage project resulted in the halting of some work until filtration equipment could be set up.
A contractor paused its earth-moving work on the west side of the course for more than two months in the late winter and spring, the Denver Department of Public Works has confirmed to The Denver Post. Testing at the time confirmed that the metal was present in unearthed groundwater but at levels considered acceptable in drinking water, DPW spokeswoman Nancy Kuhn said.
But readings exceeded the permitted level for the city to release water into storm sewers in Denver, she said. Manganese isn’t considered a health hazard but can discolor water and produce a bad odor and taste.
Testing also revealed low levels of uranium in the groundwater, Kuhn confirmed. But the radioactive metal was at concentrations considered safe for drinking, she said, and below the level that would have required filtration under the discharge permits issued for the project by the Colorado Department of Public Health and Environment.
Work on the golf course’s east side was never halted, Kuhn said, and Saunders Construction resumed work on the west side in mid-May.
“The result (of the manganese discovery) is that Saunders is filtering the water prior to discharge, and monitoring is occurring,” Kuhn said.
In a project that drew controversy and a legal challenge, crews are regrading and reconfiguring the historic Denver golf course to accommodate a stormwater detention area as part of the city’s $298 million Platte to Park Hill drainage program. The design and construction contract for City Park Golf Course was valued at $44.9 million.
Word of the contaminants — particularly the uranium — stoked concern in recent weeks among critics of the project.
In one email Wednesday to a Denver public health official, activist Bridget Walsh cited suspicions of a “cover-up.”
Kuhn said low levels of uranium are “very common in Colorado and naturally occurring.” The city did not order treatment or filtration of the groundwater before it’s discharged to sewers because it didn’t exceed the limit, she said.
At The Post’s request, Kuhn on Wednesday provided test results for 14 groundwater samples taken between April 6 and July 5. Those figures all were below the drinking water limit for manganese of 190 micrograms per liter, with fluctuating readings topping out at 135 micrograms per liter in mid-April.
The uranium readings all were below the federal Environmental Protection Agency’s limit of 30 micrograms of uranium per liter for drinking water, ranging from 1.72 to 26.8 micrograms per liter.
“Putting a filtering system in place (for manganese) caused a small delay,” Kuhn wrote in an email last week, “but the project remains on schedule” for completion next year.