Requiring that contaminated wastewater from hydrofracking be held in tanks could be a game-changer because it might not be possible to hold all that wastewater in tanks in an economical fashion.

As the Philadelphia Enquirer reports:

The Delaware River Basin Commission on Thursday proposed natural gas drilling rules in its four-state watershed that are tougher than those in the rest of Pennsylvania but that promise to do little to stem the intense wrangling over how to regulate the growing industry.
but the new rules say that

Contaminated wastewater from fracking would have to be held in tanks rather than open ponds, as is done elsewhere in the state.

The way I understand it, after the fracking fluids are injected, subsurface water must then be pulled out of the subsurface in order to get the gas out. This extracted wastewater includes groundwater from the subsurface, newly contaminated with fracking compounds.

As I recall, the volumes of wastewater are huge, far larger than a few on-site tanks can hold. If that is the case, the wastewater will have to be treated as it is produced. We’ll have to see if the technology is up to snuff in that regard. Given the variability of what will have to be treated, this will be a rather large challenge.