The problem with tight soils, like clays, saprolites, and as far as geology goes - bedrock formations, is that contamination tends to migrate primarily through preferential pathways. The best way to prevent contamination from intruding into businesses or migrating off-site is to intercept those pathways with horizontal remediation wells.

Volatile Organic Carbons (VOCs) are more or less an umbrella term, which can originate from a range of varying contaminants, such as chlorinated solvents and gasoline byproducts.