Authority: IC 13-14-8-7; IC 13-15-2-1; IC 13-19-3-1

Affected: IC 13-30-2; IC 36-9-30

Sec. 5. The owner or operator of a restricted waste site Type I or Type II or nonmunicipal solid waste landfill shall determine whether there is a statistically significant increase over background values for each constituent required in the particular ground water monitoring program that applies to the facility. The owner or operator shall make these statistical determinations each time the owner or operator monitors ground water quality at the monitoring boundary as follows:

1. (1) In determining whether a statistically significant increase has occurred, the owner or operator of a restricted waste site Type I or Type II or nonmunicipal solid waste landfill shall compare the ground water quality at each monitoring device at the monitoring boundary for each constituent to the background value for that constituent according to the statistical procedures specified under subdivision (3).
2. (2) The owner or operator shall determine whether there has been a statistically significant increase at each monitoring device at the monitoring boundary within sixty (60) days after completion of sampling.

3. (3) The most scientifically valid of the following statistical procedures that will provide a ninety-five percent (95%) level of confidence must be utilized when determining if a change in the concentration of a constituent has occurred or if ground water quality standards have been exceeded:

   1. (A) Mann-Whitney U-test.
   2. (B) Student's T-test.
   3. (C) Temporal or spatial trend analysis.
   4. (D) Any other valid statistical analysis that is appropriate for the distribution of the data being considered and that provides a reasonable balance between the probability of falsely identifying a significant difference and the probability of failing to identify a significant difference.

(Solid Waste Management Division; 329 IAC 10-29-5; filed Mar 14, 1996, 5:00 p.m.: 19 IR 1902; readopted filed Jan 10, 2001, 3:25 p.m.: 24 IR 1535; readopted filed May 14, 2007, 1:53 p.m.: 20070523-IR-329070138BFA; readopted filed Jul 29, 2013, 9:20 a.m.: 20130828-IR-329130179BFA; readopted filed Jun 14, 2019, 2:00 p.m.: 20190710-IR-329190249BFA; readopted filed Oct 16, 2024, 11:58 a.m.: 20241113-IR-329230812RFA)