“…Cleanup-( 1) actions undertaken during a removal or remedial response to physically remove or treat a hazardous substance that poses a threat or potential threat to human health and welfare, the environment, and/or real and personal property. Sites are considered cleaned up when removal or remedial programs have no further expectation or intention of returning to the site and threats have been mitigated or do not require action; or (2) actions taken to deal with a release or threat of release of a hazardous substance that could affect humans and/or [he environment.…”