(a) The facility owner or operator shall conduct an assessment when, in the opinion of the agency, there exists a possibility of migration of contaminants into or adjacent to waters in the state. The assessment shall be capable of determining:      
        (1) whether petroleum-substance waste or petroleum-substance waste constituents have entered the groundwater, surface water, or soils.       
        (2) the rate and extent of migration of any petroleum-substance waste or petroleum-substance waste constituents in the soil, groundwater, or surface water; and       
        (3) the concentrations of petroleum-substance waste or petroleum-substance waste constituents in the soil, groundwater, or surface water.       
      (b) The owner or operator of the facility shall conduct corrective action at the facility when, in the opinion of the agency, petroleum-substance waste constituents exist in the soil, groundwater, or nearby surface water at levels which are harmful to human health and safety or the environment.     
      (c) The corrective action program shall be capable of preventing the migration of contaminants and shall prevent the contaminants from exceeding the levels determined by the agency.     
      (d) The facility owner or operator shall ensure that the corrective action measures under this subsection shall be initiated and completed within a reasonable period of time as determined by the agency considering the extent of contamination. The agency may issue additional directives should the corrective action activities prove to not be effective in reducing the contaminant levels at a sufficient rate.     
      (e) The facility owner or operator shall report in writing to the agency the effectiveness of the corrective action program. The facility owner or operator shall submit these reports to the agency's central office and to the appropriate agency regional office upon request by the agency.     
     Source Note:        The provisions of this §334.504 adopted to be effective December 27, 1996, 21 TexReg 12177; amended to be effective November 23, 2000, 25 TexReg 11442