8.6 Summary

The survey identified several issues concerning the use of ISM, including how to successfully collect VOC samples with ISM, misconceptions about hot spot identification, how to use ISM data, how to apply ISM cost-effectively, and when ISM may not be the best choice. The ISM Team used the survey information to aid in developing this technical-regulatory guidance document. If the guidance document is successful, the perception of ISM will be improved, and regulatory challenges can be broken down, thus allowing ISM to be used more often and in an appropriate fashion. Table 8-2 provides a summary of the limitations and possible solutions for more widespread implementation of ISM.

Table 8-2. Limitations, solutions, and section references for using ISM

Limitations

Solutions

Section reference

Hot spots

Address during systematic planning with proper scaling, combining, or splitting DUs

Sections 3.5, 8.2, and 8.5

Vertical and horizontal DU delineation

Address during systematic planning with proper scaling or splitting DUs

Section 3.3

Acute exposure

Development of approaches for “decompositing” ISM data to estimate variability in concentrations within a DU

Section 3.1, 3.3, and 3.5

Background

Development of formalized guidance on statistical methods for comparison of site and background ISM data.

Sections 3.1, 3.2, 3.3, 4.4.3.3, 7.2.4, and 8.5.4.7

Leachability

ISM provides probability statement

Sections 3.1, 3.2, 3.3, 8.3, and 8.5

Compare with regulatory standards

Discuss with stakeholders during systematic planning

Sections 3.1, 7, and 8.5.4.5

ISM cost-effectiveness

Cost-effective when large DU, expensive analyte cost, remobilization is expensive

Section 8.5.3

Statistical challenges—compare ISM and discrete

Development of statistically sound methods for comparison of discrete and ISM data

Sections 4.4.3.2 and 8.5.4.4

Statistical challenges—95% UCL

Use Student’s-t or Chebyshev

Section 4 and Appendix A

Statistical challenges—DUs that do not correspond to exposure units

Development of statistically based methods for combining and subdividing DUs

Sections 3.1, 3.3, 4, and 7

Grinding

Not recommended for organics other than energetics by USEPA SW-846 Method 8330B; recommended for nonvolatile metals; may not be appropriate for project-specific DQOs

Section 3.1 and 6.2

Lab-processing, equipment—sieving, grinding, drying

Close coordination with laboratory is essential throughout ISM; lab business decision to have specific equipment; may need to evaluate different grinding equipment based on method detection limit requirements; laboratory should be familiar with the project-specific ISM requirements and have the facilities (space) and equipment (air-drying racks, grinders, etc.) to meet project-specific DQOs

Section 6.2

Lab—lack of nationally recognized methods

USEPA/DOD methods development

Section 6.1

Field—shipping VOC container

Complete extraction in field and ship subaliquot to the lab; transport via lab pick-up or appropriate method for hazardous goods

Section 5.4.2

Lab—VOC elevated method detection limit

Analyze by USEPA SW-846 Method 8260C SIM; additionally, may be necessary to use low-level VOC discrete sampling and/or a combination of ISM and discrete

Section 6.3.2

Lab—certification

Check with the appropriate regulatory agency; some states have certification process for lab SOPs; continued research is necessary on possible effects of ISM sample preparation procedures on COPCs, especially organics; develop and implement lab certification for ISM, possibly through NELAP

Sections 6.4.1 and 8.5.5.2

DU size and shape

Establish based on site history during systematic planning; may require remobilization if concern over results at the end of sample collection

Sections 3.1, 3.2, and 3.3

Regulators reluctance to use ISM

Review ITRC document and attend ITRC training

All



Although this document attempts to cover all the relevant topics to ISM, there are several issues which were not addressed, including the following:

  • consequences of sample grinding on assumptions made during ecological risk assessments
  • use of ISM for sampling air, sediment, or other environmental media
  • additional statistical simulation to evaluate:
    • combining DUs (Section 4.4.1)
    • comparing site to site DUs
    • comparing IS vs. discrete
    • comparing site vs. background
    • comparing oversized DUs
    • other types of sampling errors