567—120.12(455B) Landfarm closure. Unless otherwise required or approved by the department, landfarms shall be closed in one of the following ways:
	120.12(1)  Three years after the application of PCS, or
	120.12(2) At least six months after the application of PCS when documentation has been submitted and acknowledged in writing by the department that each landfarm plot has been tested as follows.
	a. 	One sample from each 10,000 ft2 (e.g., 100-foot × 100-foot area) of landfarm plot is analyzed pursuant to subparagraphs 120.6(2)“c”(1), (2), and (3). A minimum of one sample per landfarm plot shall be obtained. All samples shall be obtained from between the top 2 to 6 inches of soil.
	b. 	The results of the tests in paragraph 120.12(2)“a” demonstrate that petroleum constituent concentrations are less than 0.54 mg/kg for benzene, 42 mg/kg for toluene, 15 mg/kg for ethylbenzene, 3800 mg/kg for TEH-diesel and 0.02 mg/kg for MTBE.
[ARC 6982C, IAB 4/19/23, effective 5/24/23]