PPG Industries Inc. is agreeing to pay $1.2 million and treat polluted water seeping into the Allegheny River from a long-closed waste site, although environmental organizations called it a “slap on the wrist.” Pennsylvania’s Department of Environmental Protection and PPG signed the agreement Tuesday. PennEnvironment and the Sierra Club sued PPG in 2012, yielding a federal judge’s ruling last year that PPG is liable for the contamination. The groups say they’ll continue with their lawsuit.