8.3 Regulatory Challenges for ISM

When asked during the 2009 survey, 40% of regulator and 20% of the nonregulator respondents agreed there are specific applications for which ISM would not be endorsed. Both groups agreed that the least likely application to be endorsed for ISM is to identify areas of high concentration (i.e., hot spots).

Several states have regulations/guidance that specifically address hot spots. These states include Massachusetts and Oregon. See Table 3-2 of the Use of Risk Assessment in Management of Contaminated Sites (ITRC 2008) for more details.

Seventy-eight regulator respondents representing 25 states felt that ISM is discouraged (56%) or even expressly prohibited (3%). Three percent of respondents indicated ISM is recommended in their states (38% responded “other” or no comment).

Some states have statutory/rule prohibitions on compositing, while five states Alaska, California, Ohio, and Washington have policy/guidance restrictions on specific applications of compositing.

Only a few states (Alaska and Hawaii) generally accept the use of incremental sampling. Several states indicated that they are debating the widespread use of ISM, and Washington is updating its regulations to include ISM. Table 8-1 lists states that provided links to documents restricting or prohibiting ISM/compositing.

Table 8-1 List of states with specific restrictions on compositinga


Reason for Restriction



Discrete and maximum concentrations required



Some action levels are based on acute exposure, compositing not allowed. If calculating the 95% UCL (using FLUCL or PROUCL), must use discrete samples, and the maximum may not exceed three times the action level. Leaching action levels should be used as not-to-exceed values.



Composites of samples are not accepted without prior DEQ



Sampling average by permission only

Contact WI DNRa  http://dnr.wi.gov/topic/Brownfields/Contact.html 

New Jersey

Discrete required and composite prohibited

N.J.A.C. 7:26E-3.4(c), N.J.A.C. 7:26E-3.6(a)5

aThis information was true at the time of the survey 2009. Please contact the appropriate state to see whether this information is still current.

Language in applicable statutes or rules may specify delineation of the horizontal and vertical extent of contamination in a way that requires consideration of point concentrations rather than area averages. This would include, for example, situations in which the boundary of the contaminated area is defined through comparison of concentrations at various locations with not-to-exceed values (e.g., risk-based preliminary remediation goals or background levels).