Thursday night, the Alaska Department of Environmental Conservation gave the public a chance to comment on the proposed final cleanup of dry cleaning fluids from the River Terrace Recreational Vehicle Park near the bridge in Soldotna.
The meeting at the Kenai Peninsula Borough Building was scheduled for two hours -- from 7 to 9 p.m. -- but lasted until after 10 p.m. because of the complexity of the issue.
The dry cleaning solvent tetrachloroethene, or PCE, was used on the site from the 1960s to 1988. Contamination was first brought to the attention of the DEC in 1992, and clean up has been progressing since then.
More than 3,000 cubic yards of soil was excavated and treated in two large piles on the site by extracting the PCE vapors from it. In March of this year, the federal Environmental Protection Agency determined the treated soil was no longer contaminated.
The proposed cleanup plan for the remaining contamination deeper underground calls for restricting the use of shallow ground water for drinking and use an underground biological treatment. Further excavation was rejected by the DEC because of the $10 million price tag associated with it.
Instead, a hydrogen releasing compound, or HRC, technology will be used to clean up any remaining PCE before it leeches through the ground to the river. It is a process land owner Gary Hinkle said he proposed earlier.
The method involves drilling inspection wells in a line 30 feet from the river bank and along the Sterling Highway, as well as 100 or more temporary holes in a grid pattern in the areas still containing PCE. The HRC will be injected into the temporary holes and allowed to dissolve into the ground water.
The HRC, a proprietary product produced by a company called Regenesis Bioremediation Pro-ducts, will provide both food and a source of hydrogen to allow microorganisms to degrade the PCE into less harmful component chemicals
The DEC estimates the method will stop contaminated ground water from running off the River Terrace site within three months at a cost between $1.8 million to $3.9 million. It may take between five and 10 years to completely clean up the remaining PCE.
If the process does not work as advertised, the DEC's fall-back plan is to create a wall of iron filings in a trench through which the contaminated ground water would flow. The iron is an oxidizer that will react chemically with the PCE, stripping it of its chlorine atoms and leaving nontoxic chemicals such as ethene, according to the plan.
This technology also will halt contaminant flow into the river within three months, according to DEC, but it would take up to 15 years to complete the job. This option will cost between $1.3 million to $2.9 million.
There was much confusion at the meeting about how much PCE was reaching the Kenai River compared to the amount allowable by law.
The DEC classifies the river as a drinking water source, which has much stricter guidelines than water for other sources, such as recreation. The maximum allowable concentration of PCE in the river is 5 micrograms per liter. Only three samples have been taken from the river in front of the property, according to both DEC representative Rich Sundet and Hinkle, and two came back with no contamination at all and one came back with a concentration of 2.5 micrograms per liter -- half the allowable amount.
That drew a number of comments from the audience at Thursday's hearing.
"If it's half the maximum, why are we here?" asked several people. "What's the problem?"
It took a few more hours for it to be made clear that measurement of PCE levels for the river are not taken in the river. They are taken 15 feet from the water's edge, where concentrations are significantly higher at 660 micrograms per liter. To reach 5 micrograms per liter at the river, the contamination at 15 feet must be no greater than 15 micrograms per liter, Sundet said.
If the Kenai River, or the portion abutting River Terrace, were not classified for drinking water, the acceptable level would be 840 micrograms per liter in the river, a level higher than it is now.
However, several people spoke out against reclassifying any portion of the river to a less stringent standard.
"I appreciate the complexity of the issue, but I'm opposed to the lower level regulation," said Robert Ruffner of the Kenai Watershed Forum. "If 5 parts per billion is harmful to humans, then 840 seems high for organisms in the bottom of the river."
Joe Ray Skrha of Kenai said he has two children who swim in the Kenai River and does not want to see the levels relaxed.
"I know they ingest a lot of water," he said. "I'm against raising it to 840. We need to maintain it at 5."
The DEC has established a public comment period through June 26. No time line was given to beginning the project.
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