Groundwater Professional Bulletin Board

GUIDANCE FOR USING TEH DATA

Purpose: For some sites, groundwater samples were collected during pre-RBCA investigations and analyzed for total extractable hydrocarbons (TEH). These results merely identified contaminant levels as TEH in groundwater, but did not quantify the exact nature of the substance being measured (i.e., diesel, waste oil, or gasoline). Because of the concern, we have prepared the following protocol for the use of TEH analytical data:

• TEH GROUNDWATER DATA ACQUIRED PRIOR TO AUGUST 15, 1996: TEH groundwater data can be ignored if a site does not have a history of storing, using, or dispensing either from aboveground or underground storage the following compounds: diesel, kerosene, JP4, JP5, racing fuel, hydraulic oil, fuel oil, heating oil, motor oil, waste oil, or any other non-gasoline product.
  
  However, if soil TEH data also acquired prior to August 15, 1996, exists and exceeds a Tier 1 Target Level, then current groundwater samples must be obtained for determination of TEH contaminant levels (refer to Subrule 567--135.18(4) of the Iowa Administrative Code). These analyses must be used for a RBCA evaluation, unless the exception criteria noted in item 2 are met.
  
  
• TEH SOIL AND GROUNDWATER DATA ACQUIRED AFTER AUGUST 15, 1996: All data identified as TEH diesel or TEH waste oil must be used for the RBCA evaluation.
  
  Exception clause: TEH data identified as TEH diesel and TEH waste oil and acquired after August 15, 1996, may be ignored only in those cases where a detailed site history can be provided to show complete history of petroleum use at the site. This history must include all periods of time when petroleum was stored at the site (either in aboveground storage tanks, underground storage tanks, drums, etc.) and is not limited to the ownership of the current owner. Petroleum products of concern include, but are not limited to, diesel, kerosene, JP4, JP5, racing fuel, hydraulic oil, fuel oil, heating oil, motor oil, and waste oil.
  
  NOTE: The history needed to meet the exception clause is, in a modified form, already a requirement of the RBCA Tier 1 and Tier 2 assessments. However, in many cases, insufficient information is provided to substantiate whether or not products other than gasoline have been used or stored at a site. Where the past history is unknown or unclear, the TEH contaminant data must be used.