Tex. Natural Resources Code § 91.656

(a) Before the commission evaluates any plan or report detailing the remediation goals and proposed methods of remediation, the person desiring to participate in the voluntary cleanup program must enter into a voluntary cleanup agreement that sets forth the terms and conditions of the evaluation of the reports and the implementation of work plans.

(b) A voluntary cleanup agreement must provide for:

(1) recovery by the commission of all reasonable costs:

(A) incurred by the commission in review and oversight of the person's work plan and reports and as a result of the commission's field activities;

(B) attributable to the voluntary cleanup agreement; and

(C) in excess of the amount of fees submitted by the applicant under Section 91.654;

(2) a schedule of payments to the commission to be made by the person for recovery of all commission costs fairly attributable to the voluntary cleanup program, including direct and indirect costs of overhead, salaries, equipment, and utilities, and legal, management, and support costs; and

(3) appropriate tasks, deliverables, and schedules.

(c) The voluntary cleanup agreement shall:

(1) identify all statutes and rules with which the person must comply;

(2) describe any work plan or report to be submitted for review by the commission, including a final report that provides all information necessary to verify that all work contemplated by the voluntary cleanup agreement has been completed;

(3) include a schedule for submitting the information required by Subdivision (2); and

(4) state the technical standards to be applied in evaluating the work plans and reports, with reference to the proposed future land use to be achieved.

(d) If an agreement is not reached between a person desiring to participate in the voluntary cleanup program and the commission on or before the 30th day after good faith negotiations have begun:

(1) the person or the commission may withdraw from the negotiations; and

(2) the commission retains the person's application fee.

(e) The commission may not initiate an enforcement action against a person who is in compliance with this section for the contamination or release that is the subject of the voluntary cleanup agreement or for activity that resulted in the contamination or release.