(a) For grid samples which are chemically analyzed individually, the PCB concentration applies to the area of inference as described in § 761.283(d).

(b) For grid samples analyzed as part of a composite sample, the PCB concentration applies to the area of inference of the composite sample as described in § 761.283(d) (i.e., the area of inference is the total of the areas of the individual samples included in the composite).

(c) For coordinate pair samples analyzed as part of a composite sample, in accordance with §§ 761.283(c)(2) and 761.289(b)(2)(ii), the PCB concentration applies to the entire cleanup site.