(a) Before including any type B methodologies in the Assessment Plan, the authorized official must confirm that at least one of the natural resources identified as potentially injured in the preassessment screen has in fact been exposed to the released substance.

(b) Procedures.

(1) Whenever possible, exposure shall be confirmed by using existing data, such as those collected for response actions by the OSC, or other available studies or surveys of the assessment area.

(2) Where sampling has been done before the completion of the preassessment screen, chemical analyses of such samples may be performed to confirm that exposure has occurred. Such analyses shall be limited to the number and type required for confirmation of exposure.

(3) Where existing data are unavailable or insufficient to confirm exposure, one or more of the analytical methodologies provided in the Injury Determination phase may be used. The collection and analysis of new data shall be limited to that necessary to confirm exposure and shall not include testing for baseline levels or for injury, as those phrases are used in this part.

[51 FR 27725, Aug. 1, 1986. Redesignated and amended at 61 FR 20610, 20611, May 7, 1996]