Complex sentence: A separate survey in 2012 found dangerous levels of toxic substances; chlorobenzene levels were 78,899 times safe levels in soil and 94,799 times those in groundwater.
Split into simpler sentences: A separate survey in 2012 found dangerous levels of toxic substances. The survey found that chlorobenzene levels were 78,899 times safe levels in soil and 94,799 times those in groundwater.