From The Denver Post (Bruce Finley):
Dealing with the Suncor spill north of Denver, detected in November 2011, still ranks among the toughest environmental challenges in the region. Another oil and gas industry spill this year tainted Parachute Creek in western Colorado with benzene. Spills from industry pipelines and storage facilities at 12 other locations have contaminated groundwater with benzene, prompting state health department orders for corrective action. About 20 percent of the 300-400 oil and gas spills reported annually to state commissioners reach groundwater.
The Colorado Department of Public Health and Environment is pressing companies responsible for the big spills to quickly remove all benzene from soil, water and air. But a review of Suncor case documents and interviews show that, even though benzene technically is easier than other toxic chemicals to remove, full cleanup can be complicated and slow…
CDPHE officials have identified a broken “dead-leg” pipe beneath a storage tank as the source of the Suncor spill. It was capped in February 2011, yet liquids that flowed from that pipe into an underground toxic plume continue to foul surface water in Sand Creek, which flows into the South Platte. Benzene-laced groundwater also has spread in other directions: along the concrete-lined Burlington irrigation ditch, beneath the adjacent Metro Wastewater Plant and under the bed of Sand Creek. The plume does not reach the river directly. The overall size is said to be stable or shrinking. But the levels of benzene — a widely-used a chemical contained in petroleum, known to cause blood cancer — this month remained around 33 parts per billion in the South Platte, state data show. The federal safe drinking water standard is 5 ppb. The river concentrations are down from 45 ppb in April and about 240 ppb a year ago. One mile downriver, the benzene dissipates to around 4 ppb, and 3 miles downriver the level is negligible. In Sand Creek, however, benzene remains significantly elevated, according to the data that comes from tests done by Suncor contractors…
Since 2011, he and other CDPHE officials have issued Suncor at least 10 formal orders to complete about 200 actions, including repairs near another storage tank. Today, underground walls of clay have been built around nearly half the known perimeter of the plume. Suncor crews have removed more than 1.2 million gallons of liquid hydrocarbons from trenches that crews dug after the spill was revealed. “The footprint of the contamination continues to shrink. The extensive remediation systems Suncor has designed and installed … are working effectively to reduce the contamination,” company vice president John Gallagher said in an e-mailed response to queries. “It is unlikely that there are other underground sources of contamination of a size that would reverse the positive trend we are seeing.”[…]
CDPHE officials in recent months have ordered the installation of more walls, monitoring wells to track toxic plumes, and aeration systems that suck benzene vapors from soil. More than 100 aeration wells have been placed between the refinery and Metro Wastewater, where required construction projects are in progress. Extracting benzene from soil is tricky because this transfers toxic material into the air. State air officials recently ordered Suncor to install emission controls, including charcoal filters, to minimize air pollution. They’ve directed Suncor to apply for an air pollution permit.
The CDPHE team also is demanding documentation of when and how broken pipes near storage tanks were repaired, including work orders. And CDPHE has ordered Suncor to hire an independent auditor to review its system for maintaining and inspecting storage tanks.