Or. Admin. Code § 340-122-0355 - Evaluation of Analytical Results

(1) The results of the soil analyses shall be interpreted as follows:

(a) If a sample has a concentration less than or equal to the required matrix level, the area represented by that sample meets the requirements of these rules;

(b) If a sample has a concentration exceeding the required matrix level by more than ten percent, the area represented by that sample does not meet the requirements of these rules. Further remediation, sampling, and testing is necessary until the required level is attained;

(c) If a sample has a concentration exceeding the required matrix level by less than ten percent, the responsible person has the option of collecting and analyzing two more samples from the same area and using the average of all three to determine if the standard has been met; or further remediating the area and then collecting and analyzing one new sample and using the concentration of the new sample to determine if the standard has been met. Alternatively, the Department has the options of approving the cleanup with no further action, requiring that more samples be taken, or requiring further cleanup and subsequent sampling. Such a decision shall be made based upon the analytical results of other samples from the site, best professional judgment made from a visit to the site, the apparent extent of contamination, and other site specific factors deemed appropriate.

(2) A site shall be considered sufficiently clean when all of the sampled areas have concentrations less than or equal to the required matrix cleanup level, and when the possibility of any human contact with the residual soil contamination remaining on the site has been precluded.

(3) If water is present in the tank pit, the Department shall decide if cleanup may proceed under these rules or if further action must be taken pursuant to OAR 340-122-0240. This decision shall be based on, but is not limited to:

(a) The apparent extent of the contamination;

(b) The likelihood that groundwater contamination exists beyond the boundaries of the tank pit;

(c) The likelihood that the BTEX concentrations in the water and the BTEX and TPH concentrations in the soil indicate a situation which poses a threat to public health, safety, and welfare or the environment; and

(d) Any other site-specific factors deemed appropriate by the Department.

(4) If a pocket of contamination exceeding the required Matrix cleanup level is located under a building or other structure where further removal would endanger the structure or be prohibitively expensive, the Department must be notified of this situation. The Department shall then decide whether such contamination can remain without threatening public health, safety, and welfare or the environment. If not, the Department shall require further remediation.

(5) For waste oil contaminated sites, all detectable levels of volatile chlorinated solvents, volatile aromatic hydrocarbons, PCBs, or leachable metals shall be reported to the Department as soon as these results are known. The Department shall then decide whether the cleanup shall continue under these rules or whether further investigation is warranted under OAR 340-122-0205 through 340-122-0260 or 340-122-0010 through 340-122-0115.

Notes

Or. Admin. Code § 340-122-0355

DEQ 15-1989, f. & cert. ef. 7-28-89 (and corrected 8-3-89); DEQ 46-1990, f. 12-26-90, cert. ef. 3-1-91; DEQ 23-1998, f. & cert. ef. 11-2-98

Stat. Auth.: ORS 465.400 & ORS 466.746

Stats. Implemented: ORS 465.200 - ORS 465.455 & ORS 466.706 - ORS 466.835