Texas Health and Safety Code - HEALTH & SAFETY § 361.276. Apportionment of Liability

(a) If the release or threatened release caused by a person's acts or omissions is proved by a preponderance of the evidence to be divisible, that person is liable only for the elimination of that release or threatened release attributable to the person. If the release or threatened release is not proved to be divisible, persons liable under Section 361.272 or 361.273 are jointly and severally liable for eliminating the release or threatened release.

(b) In this section, “divisible” means that the waste released or threatened to be released has been and is capable of being managed separately under the remedial action plan.