Six. That is the new number of tanks believed to be leaking at the Hanford Nuclear Waste Site in Washington—up from an original disclosure of one leaking tank. And whatever the fix, it will cost plenty of money.

While officials knew that at around 70 of the 149 single-shell tanks housing radioactive waste, some since World War II, had leaking issues dating decades into the past, they believed the leaking—roughly about 1 million gallons in total—was stopped by 2004, when the last of the easily removable liquids was pumped out of the tanks. All that was left in the underground storage bins was a mudlike sludge.

But that mix of mud may have changed consistency over time, freeing up more liquids for seepage out of what officials are now saying are six tanks. Now the solutions aren’t readily accessible.

One quick fix involves covering even more ground with a barrier—either truck bedliner-type plastic or asphalt—to block more water and snow melt from mixing and spreading the liquid already leaked and in the soil. A solution on the opposite spectrum of ease and cost includes devising a quicker way to return to the leaking tanks for more pumping.

Some of the single-shell tanks, such as T-111, the first of the repeat offenders found leaking, were thought cleared of liquid as far back as the mid-1990s. Hanford’s waste removal techniques have grown exponentially since that time, with multiple sluicing methods devised and robotic arms and machines leading the cleaning. A combination of liquids separating from solids within the tank and the new methods could yield plenty more gallons of retrievable waste. But clearing out the liquid would cost millions of dollars that the government doesn’t have.

And it would also necessitate a place to put the new batch of waste, as Hanford’s 28 double-shell tanks (don’t get too excited about those, however, as at least one of those is leaking through the first layer) will soon hang a “no vacancy” sign on their doors. With the vitrification plant still in the design and construction phase, Hanford lacks an accessible long-term storage solution for the 56 million gallons of waste on site.

Like I said, whatever the solution—especially a long-term solution—it involves millions of dollars the government simply doesn’t have. The government also doesn’t have the luxury of letting radioactive waste continue to infiltrate the ground near the Columbia River. Something has to give. Hopefully it isn’t more single-shell tanks. 

Tim Newcomb is Engineering News-Record’s Pacific Northwest contributor. He has also written for TIMEPopular MechanicsPopular Science and more. You can follow him on Twitter at @tdnewcomb or visit his website here.