Department of Health Seal

TGM for the Implementation of the Hawai'i State Contingency Plan
Section 8.1
SELECTING A FIELD SCREENING METHOD

8.1 SELECTING A FIELD SCREENING METHOD

There are a number of important considerations that must be taken into account when proposing a field screening method. This list includes items that should be evaluated (at a minimum) for each project:

  • Target Analytes: Field screening methods generally provide results for either a specific compound or a specific class of compounds. For example, if the site contaminant is petroleum, but the specific concern is polynuclear aromatic hydrocarbons (PAH), select a method that targets PAHs, not just petroleum hydrocarbons. Additionally, the available field screening methods may not have adequate selectivity to test for specific compounds within a class of chemicals (e.g., individual PAHs or PCB isomers).
  • Action Levels: Field screening methods may have higher detection limits than laboratory methods and some methods may not be sensitive enough to meet applicable action levels. Field methods should have adequate sensitivity to meet the goals and objectives established in the site SAP/QAPP.
  • Matrix Effects: Some field screening methods may have limited usefulness with certain sample matrices. An example of matrix effects is soil with a high clay or organic carbon content, which can cause an immunoassay test to be biased low. Other examples of matrix effects include moisture or the presence of large pebbles in soil being screened with a field XRF. A preliminary study using soil from the targeted site is recommended prior to the beginning of field work in order to evaluate potential limitations of the proposed field screening methods. Calibration of equipment with site-specific or soil type-specific samples/standards and other methods recommended by the field screening test kit or instrument manufacturer can compensate for some of these effects.
  • Data Use: Field screening methods generate a wide range of data quality, from purely qualitative data (e.g., presence or absence) to quantitative data that rivals or even exceeds laboratory data depending on the sample type, processing and QA/QC (e.g., field XRF). The HEER Office currently requires laboratory-quality confirmation data for final decision making, especially for clearance of “clean” areas from further investigation. Field screening can be used to designate DUs (see TGM Section 3) for more detailed characterization and/or guide initial removal/remediation actions (refer to XRF case study in this Section). Field screening is best employed when the site contaminants of concern are known and a better understanding of the nature and extent of the contamination is needed for site characterization or for a removal or remediation response action. Particular attention should be focused on those portions of the site characterization and/or removal/remediation action that require documentation of contaminant levels below applicable EALs for final clearance (i.e., “Perimeter DUs”). Laboratory confirmation data will generally be required for these areas.
  • Training: Many field screening methods employ specific kits or special field equipment, which requires properly trained personnel to conduct the testing. Standard operating procedures for the use of any field screening method(s) should be included as an Appendix to site-specific Sampling and Analysis Plans.

More information on topics discussed in this section can be found in Site Investigation Design and Implementation (see TGM Section 3) and in Data Quality Assurance and Quality Control (see TGM Section 10).