Geologic Vulnerability - Urban Watersheds: Geology, Contamination, and Sustainable Development - page 210

• Potable water was supplied by the municipality and the source was more than
16 km (10 mi) away
• The contamination did not extend beyond the property boundary
The types of contaminants detected at the facility included
• Volatile organic compounds (VOCs) including
• DNAPLs commonly referred to as chlorinated solvents used to degrease and
clean metal surfaces
• Light nonaqueous phase liquids (LNAPLs) used as solvents, paint thinners,
and cleaning products, and are common constituents in fuels such as gasoline
• Polynuclear aromatic hydrocarbons (PNAs or PAHs) commonly used as lubricants
and motor oils and cutting fluids
• PCBs used in electrical equipment
• Heavy metals (arsenic, chromium, and lead) commonly used in paints and pig-
ments, batteries, and metal plating
A list of specific chemical compounds, highest concentrations detected, and estimated
contaminant mass remediated are listed in Table 6.4.
Soil excavation and disposal of the contaminated soils at a licensed landfill was the
remedial method of choice for the contamination at this site. The overriding considerations
for selecting this method were: the contaminated areas were less than 1.5 m deep and
were not located beneath any buildings; the activities could be conducted quickly with-
out disturbing ongoing facility operations, and it represented the lowest cost alternative.
Approximately 5,400 m 3 (7,000 cubic yards)—equivalent to 9,072 ton of soil (10,000 ton)—
was excavated and transported to a local landfill for disposal. The total cost for investiga-
tion and remediation was approximately $400,000. This translates into a remediation cost
per kilogram of contaminant of $362 ($800/lb).
After the remediation was verified by the regulatory authority through the collection
and analysis of the soil samples taken from each area remediated, closure was granted
and a “No Further Action Required” letter was issued for the site. The closure was
deemed unrestricted, meaning the site had been remediated to comply with residential
land use requirements. Eighteen months had elapsed since the Phase I environmental site
assessment.
6.5.2 Site 2: High Vulnerability Site
Site 2 is a former heavy manufacturing facility approximately 3.2 ha (8 ac) in size that oper-
ated for 30 years. Figure 6.5 shows the layout of the site.
The Phase I environmental site assessment identified four RECs:
• Two former chemical storage areas . Evidence of surface staining indicated some spill-
age of liquids at one storage area located on bare ground near an area storing
waste paints. An additional waste storage area was located on stained asphalt
pavement that was heavily cracked and broken.
• A former underground storage tank . This underground storage tank once stored
gasoline and was identified as a REC because during its removal (1) it was not