MO RISK-BASED CORRECTIVE ACTION FOR PETROLEUM STORAGE TANK SITES SAMPLING FOR POLYNUCLEAR AROMATIC HYDROCARBONS

Hazardous Waste Program fact sheet
04/2014
Division of Environmental Quality Director: Leanne Tippett Mosby
PUB2160

When is this fact sheet applicable?
This fact sheet is applicable when evaluating a site using the 2004 Missouri Risk-Based Corrective Action (MRBCA) process for petroleum storage tanks.  The 2013 MRBCA process for petroleum storage tanks includes information regarding this topic in Section 5.8.3.

What are Polynuclear Aromatic Hydrocarbons?
Polynuclear aromatic hydrocarbons are hydrocarbon compounds with multiple benzene rings. Polynuclear aromatic hydrocarbons are typical components of asphalts, fuels, oils and greases. They are also called Polycyclic Aromatic Hydrocarbons. Polynuclear aromatic hydrocarbons are associated with heavy petroleum, including diesel fuel, jet fuel, kerosene, heavy fuel oils and waste oil. The analytical standards used under the Missouri Risk-Based Corrective Action (MRBCA) process report these types of petroleum as either Diesel Range Organics or Oil Range Organics.

What are the MRBCA provisions for sampling polynuclear aromatic hydrocarbons in surficial soil?
Surficial soil is soil from the surface of the ground to a depth of three feet. Risks associated with polynuclear aromatic hydrocarbons are the greatest through ingestion and dermal contact exposure routes. All surficial soil samples that contain total petroleum hydrocarbons with Diesel Range Organics or Oil Range Organics at a concentration above laboratory detection limits or the required reporting limits shown in Table 5-3 of the MRBCA guidance, whichever are lower, must be analyzed for the polynuclear aromatic hydrocarbons listed in Table 5-1 of the MRBCA guidance. 

What are the MRBCA provisions for sampling polynuclear aromatic hydrocarbons in subsurface soil?
Subsurface soil is soil in the zone between a depth of three feet and the top of groundwater. Due to its low vapor pressure, polynuclear aromatic hydrocarbons do not readily migrate in a vapor form. Therefore, the vapors to indoor air pathway are of negligible concern in evaluating the risks posed by polynuclear aromatic hydrocarbons. Except for naphthalene, the Department of Natural Resources does not require that every subsurface soil sample containing detectable total petroleum hydrocarbons-Diesel Range Organics or total petroleum hydrocarbons-Oil Range Organics be analyzed for the polynuclear aromatic hydrocarbons listed in Table 5-1 of the MRBCA guidance. Rather, samples should be analyzed for polynuclear aromatic hydrocarbons as follows:

What are the MRBCA provisions for sampling polynuclear aromatic hydrocarbons in groundwater?

Polynuclear aromatic hydrocarbons generally do not readily partition into groundwater in significant concentrations because polynuclear aromatic hydrocarbons tend to have very low water solubilities and a tendency to absorb to soil. Therefore, with the exception of naphthalene, the department does not require all groundwater samples having detectable total petroleum hydrocarbons-Diesel Range Organics or total petroleum hydrocarbons-Oil Range Organics be analyzed for the polynuclear aromatic hydrocarbons listed in Table 5-1 of the MRBCA guidance. Rather, groundwater samples shall be analyzed for polynuclear aromatic hydrocarbons in accordance with the following provisions:

For More Information
Missouri Department of Natural Resources
Hazardous Waste Program
Tanks Section
P.O. Box 176
Jefferson City, MO 65102 0176
1-800-361 4827 or 573-751-6822 office
573-526-8922 fax
www.dnr.mo.gov/env/hwp/tanks/tanks.htm
www.dnr.mo.gov/env/hwp/index.html