the statutory scheme. On the day of the incident, the plaintiffs themselves took no active steps toward cleanup; others neutralized the chemical threat. And unlike the homeowners in Tanglewood, for example, the plaintiffs here left their residences primarily in fear of their own safety — an understandable response, but not a “necessary response” taken primarily to further the goal of prompt, efficient cleanup of the perceived hazard. In contrast, the Tanglewood subdivision residents — whose houses rested on a former toxic dump site— were forced to relocate because the cleanup effort required the demolition of their houses. Tanglewood East Homeowners v. Charles-Thomas, Inc., 849 F.2d 1568, 1575 (5th Cir.1988); see also Amoco Oil Co. v. Borden, Inc., 889 F.2d 664, 669-70 (5th Cir.1989) (<HOLDING>) (emphasis added). Any expenses the plaintiffs
holding that where the defendants  107 claim was based on remediation costs they incurred and may incur in the future as the result of a lawsuit instituted under  107a they did not demonstrate that they incurred necessary costs of response within the meaning of  107a holding that the proper remedy for future response costs is not a present lumpsum payment of anticipated expenses but instead a declaratory judgment award dividing future response costs among prps holding that response costs can be necessary even though the agency that required cleanup never approved the response actions taken holding that to justifiably incur response costs one necessarily must have acted to contain a release threatening the public health or the environment holding that investigatory costs are considered costs of response under cercla