runoff “caused” the response costs incurred. While defendants have proffered evidence demonstrating that lead was inherent in the tar-like material, and that the lead that was inherent was alone sufficient to justify the removal effort, this does not preclude a finding that lead that entered the property through the storm drain system might also have provided a basis for remediation. See Boeing, supra, 207 F.3d at 1185. The court is mindful of the Ninth Circuit’s formulation of the causation standard in Boeing — i.e., that there must be a showing that “either polluter’s conduct would have caused the same response cost to be incurred in the same amount, and [that] the[ir] conduct was of substantially equal blameworthiness.” Id. See also Browning-Ferris Industries, supra, 195 F.3d at 958 (<HOLDING>). Seemingly, other courts have not required a
holding that parties liable for at least a portion of the costs of remediating a hazardous site are limited to the contribution scheme under section 9613f of cercla holding that a potential prison sentence of up to five years was clearly serious holding that response costs can be necessary even though the agency that required cleanup never approved the response actions taken holding that a portion of plaintiffs response costs should be allocated to a defendant whose pollution was serious enough  to require that the site be cleaned up holding that investigatory costs are considered costs of response under cercla