(b) The department may grant a variance from the requirements of subdivision (a) and Section 25209.3, concerning equipping the land treatment unit with liners and a leachate collection and removal system, if the owner or operator demonstrates to the department and the department finds all of the following:

1. (1) If the land treatment unit is an existing land treatment unit, no hazardous constituents have migrated from the treatment zone of the land treatment unit into the vadose zone or into the waters of the state. In making this demonstration the owner or operator shall take a sufficient number of core samples in, beneath, and surrounding the treatment zone of the land treatment unit to characterize the chemical constituents in the treatment zone, in the immediate area of the vadose zone surrounding the treatment zone, and in the area of the vadose zone beneath the treatment zone and shall submit groundwater monitoring data sufficient in scope to demonstrate that there has been no migration of hazardous constituents into the vadose zone or into the waters of the state. The owner or operator, as an alternative to taking these core samples, may use the data obtained from any land treatment demonstration required by the department before issuing a hazardous waste facilities permit pursuant to Section 25200, if the data were obtained not more than two years prior to the application for the variance and is sufficient in scope to demonstrate that there has been no migration of hazardous constituents into the vadose zone or into the waters of the state.
2. (2) Notwithstanding the date that the land treatment unit commences operations, the design and operating practices will prevent the migration of hazardous constituents from the treatment zone of the land treatment unit into the vadose zone or into the waters of the state.
3. (3) Notwithstanding the date that the land treatment unit commences operations, the design and operating practices provide for rapid detection and removal or remediation of any hazardous constituents that migrate from the treatment zone of the land treatment unit into the vadose zone or into the waters of the state.

(c)

1. (1) The department may renew a variance only in those cases where an owner or operator can demonstrate, and the department finds, both of the following:

   1. (A) No hazardous constituents have migrated from the treatment zone of the land treatment unit into the vadose zone or into the waters of the state.
   2. (B) Continuing the operation of the land treatment unit does not pose a significant potential of hazardous constituents migrating from the land treatment unit into the vadose zone or into the waters of the state.
2. (2) In making the demonstration for the renewal of a variance pursuant to this subdivision, the owner or operator may use field tests, laboratory analyses, or, operating data.