Some gifts keep on giving, but not in a good way.
In the late 1980s and 1990s, several Bayfield property owners had to deal with old leaking underground fuel tanks that came with the property. They were required to remove the tanks and contaminated soil.
After years of efforts, a network of wells were drilled in Mill Street last fall to inject mitigation chemicals. Monitoring this year showed one small area still contaminated with benzene. The town is being asked by the state to sign off on a "Tier 3 closure" and a declaration that everything that can be done has been done.
Town Manager Chris La May said this allows for a contaminant above Colorado Division of Oil and Public Safety (OPS) limits to remain if it's under a public road without other "points of exposure." It requires a consent agreement between the town as property owner and OPS.
Brad Thoms from ALTUS Enviromental Services reported to town trustees on July 21. He referred to it as the Capri Electronics site. That was a small local company that owned the property that is now the B Diner parking lot. Four underground tanks were removed in 1989 along with piping and 50 cubic yards of impacted soil, Thoms said.
In 2001, the soil contamination was found to extend south under Mill Street, he said. In December 2002, another 60 cubic yards of soil was removed; then another 66 cubic yards in 2011. "After 10 years, we have it down to one area," Thoms said. "The concern is benzene. The groundwater across the street is very shallow, river bed soils. ... Last October we did a bunch of (activated carbon slurry) injections. We're down to this little area under the road on the south side of the street."
In that spot the benzene concentration is 25 to 30 parts per billion, which is more than the OPS clean-up target, Thoms said.
Tier 3 closures are considered low risk situations, OPS representative Vinny Secondo said by phone link. "We have four tiers of closure evaluation," he said. "Tier 1 is the most stringent standard. Tier 2 allows contamination to stay above state standards if there's a low threat. Tiers 3 and 4 are low level contamination in a public right-of-way. Tier 4 is similar with off-site contamination under a road and maybe property on the other side of the road."
He continued, "We're talking about really evaluating the risks." He cited the years of remediation that has already been done and said there is "low risk from residual contamination off-site. I think we are dealing just with the irrigation ditch which is surface water. We think there's very low risk to that. So we are looking at the Tier 3 closure. All the remediation that's been done we consider to be the maximum practicable. We've exhausted our efforts to clean up the contamination, but there's still some residual contamination. The state is looking at this as the maximum extent practical, that a Tier 3 evaluation would be the best path forward."
Trustee Ed Morlan asked if they had tested ditch water. Thoms said he collected samples that day and expected results in two weeks.
Secondo said sampling is recommended, but finding any concentration of contamination in the ditch water is unlikely unless it's visible on the surface.
La May worried about impacts on the closest private property owners, such is if they wanted to sell their property.
That's possible, Secondo said, but it doesn't appear that any petroleum has gone beyond compliance wells put in in 2004 or 2005. If it showed up there, more monitoring wels would probably be drilled. "We have the extent defined. It doesn't appear to go any further," he said. "We're trying to do clean-up based on risk rather than someone's property value. ... The goal is to make sure there are no surprises to anyone."
What happens if the town doesn't sign the consent agreement, La May asked.
"If consent is given, we do the closure evaluation," Secondo said. "If consent isn't given, the state might put it on a semi-annual or annual monitoring program. If it's low risk, the state might not issue more funding." Thoms said montoring has been four times a year.
In his staff report, La May said the advantage of signing the consent agreement "is that remediation efforts would cease and the town's roadway would not continually be impacted. OPS informs that further remediation efforts would include additional drilling and injection on Mill Street. ... If the town was to excavate or replace a water line, we would have to request that they reopen the site to seek reimbursement for any removal and replacement of material or remediation necessary for the project. OPS informs that there is no safety risk."
Morlan and trustee Michelle Nelson wanted to see results of the ditch samples before any decision.
"Once we get the ditch results, we'll tailor the agreement," Thoms said. He promised results before the board's Aug. 4 meeting. There was no discussion of that at the Aug. 4 meeting, but La May told the Times the results showed no detectable amount.
On the consent agreement, he said, "If they (OPS) want this agreement, they'll have to prepare it. I'm not going to have my attorney do it. Now they want to talk to the town attorney, which will cost the town money. They might just do more wells before September and then re-pave it."
