From The Denver Post (Bruce Finley):
Neither state regulators nor Suncor has calculated how much cancer-causing benzene and other contaminants have entered the waterways from an underground plume spreading from the refinery under the adjacent Metro Wastewater Treatment Plant. But interceptor trenches, vapor-extraction systems and recovery wells over the past five months have removed about 697,200 gallons of material from the ground, Suncor officials said Tuesday in a response to Denver Post queries.
A fountain aeration system designed to separate benzene from water, before the creek reaches the river, has been shut down. Colorado Department of Public Health and Environment regulators ordered the shutdown April 24. Health department spokesman Warren Smith said this was done to evaluate the effectiveness of Suncor’s underground walls and extraction systems installed on Metro Wastewater property near Sand Creek. Smith acknowledged “fluctuations” in benzene levels in the creek and river but disputed any overall upward trend…
“We believe that the permanent solutions being installed and operated — trenching systems and treatment systems on both Suncor and Metro’s property — will effectively isolate and manage the plume and dramatically lower the dissolved benzene level in Sand Creek,” company vice president John Gallagher said in a prepared response. The latest water-test data show benzene levels at 400 parts per billion or higher in the South Platte and at two monitoring wells along Sand Creek. The federal drinking-water standard for benzene is 5 ppb. At the South Platte location (about 50 feet downriver from the confluence with Sand Creek), the 400 ppb detected April 25 was more than double the 180 ppb recorded April 6 and 73 percent higher than the 230 ppb recorded Dec. 2 — when EPA overseers launched an emergency response. Three monitoring sites along Sand Creek were tested April 2-4 and again April 9. During that period, benzene levels at the sites increased — to 150 ppb from 12 ppb; to 490 ppb from 89 ppb; and then to 510 ppb from 73 ppb. On April 25, the two sites nearest the creek bank, where black goo began oozing into the creek in November, still showed benzene concentrations of 410 ppb and 450 ppb.