Extending deadlines for cleaning up Hanford's worst waste by years or decades is not ideal, but officials who reached a proposed settlement agreement say meeting the proposed new deadlines is more realistic.

A round of public hearings in Oregon and Washington starts this month on the proposed agreement, but already officials are answering questions like why these deadlines would be more enforceable than legal deadlines that already have been missed. And why leaving waste longer in leak-prone underground tanks may be a better option than building new storage tanks.

"The bottom line is that while we don't like the dates, we don't believe it is technically possible to dramatically move them forward, at least right now," said Ken Niles, assistant director of the Oregon Department of Energy, in a written response to concerns posted in an online discussion.

The settlement agreement reached between Washington and DOE was announced in August during a visit by Energy Secretary Steven Chu to the Hanford nuclear reservation.

It proposes a federal court order requiring that the 16 tanks in the C Tank Farm -- which are among 149 single-shell tanks holding radioactive waste underground at Hanford -- be emptied by 2014. DOE missed a legal deadline to have them emptied three years ago.

The court would order DOE to have a "hot start" to the vitrification plant, which is being built to treat the waste, by 2019. The current deadline is 2011, which neither DOE nor its regulators believe is achievable.

Longer-term deadlines would be adjusted in the legally binding Tri-Party Agreement, rather than under the consent decree. DOE would be required to have all single-shell tanks emptied by 2040, an extension of 22 years. All waste would need to be treated by 2047 rather than the current deadline of 2028.

The most distant deadline, which likely won't occur while many of those who negotiated the agreement are still living, requires closing the 28 double-shell tanks by 2052. Waste in the leak-prone single-shell tanks is being emptied into the newer double-shell tanks until it can be treated.

The proposed settlement agreement would resolve a lawsuit filed by Washington against DOE in 2008 after it became apparent that DOE could not meet legal deadlines for emptying tanks and treating the waste. Oregon, an intervenor in the lawsuit, reached a separate agreement.

It's significant that the proposed settlement includes a consent decree that would become a court order directly enforceable by the court, said Mary Sue Wilson, Washington state senior assistant attorney general.

"If you are DOE and have a court order you do things on schedule," she said at a workshop last week in Richland on the proposed settlement agreement. "I think it will motivate them to do everything they can to meet it."

If DOE does not meet the new deadlines in the consent decree and a judge does not think it has a good reason for being out of compliance, several steps are possible, she said.

They range from a fine to finding DOE in contempt, which could result in officials ordered to serve time, she said.

In addition, Washington has made clear that the proposed agreement will be called off if DOE does not recommend continuing a ban on shipping several types of radioactive waste to Hanford for disposal or storage until at least 2022. Included in the ban are some types of low-level radioactive waste plus transuranic waste, which usually is waste contaminated with plutonium.

DOE is set to release a comprehensive environmental study later this month in draft form that is expected to include the recommendation.

Work fell behind to build the vitrification plant for a variety of technical, budget and management issues. However, construction and design of the plant have been proceeding steadily for several years and work is close to being 50 percent done.

Work to empty underground tanks has been more technically difficult than anticipated, with multiple robots and other technology developed to try to get radioactive solids out of the bottoms of the tanks. In addition, with work delayed on the vitrification plant, DOE is running out of space in its double-shell tanks to hold waste removed from the single-shell tanks.

Hindsight shows it was a mistake to support DOE's determination in 1995 that more double-shell tanks were not needed, Niles said in his internet response. At the time, the cost for the new tanks seemed exorbitant and it was believed that a vitrification plant would soon be operating to free up more space in the double-shell tanks, he said.

"No one then imagined that we were still 25 years from having an operational vitrification facility," he said. "Had we known or even suspected that, I think all of us would have pushed for building new waste storage tanks and aggressively emptying the single-shell tanks."

If a decision were made now to build new double-shell tanks to get more waste out of the single-shell tanks, it likely would be at least 2017 before the new tanks were approved, funded, designed and constructed, Niles said. Then DOE would still have to retrieve and move waste to the new tanks.

"If we have another major delay in the start of the vitrification facilities, we will of course all once again realize we gambled badly and that we should have built more tanks," he said.

However, proposed Tri-Party Agreement changes require DOE to develop contingency plans, including for the construction of new tanks, if there are further delays in the vitrification plant, he said.

Public comments on the proposed settlement agreement are being accepted until Dec. 11. Comments can be e-mailed to TPACH@rl.gov or mailed to Lori Gamache, DOE Office of River Protection, P.O. Box 450, MSIN H6-60, Richland, WA 99352.