Okla. Admin. Code § 252:515-9-74

Current through Vol. 41, No. 19, June 17, 2024

Section 252:515-9-74 - Statistical analysis

(a)60-day deadline. Except as provided for in (f) of this Section, within 60 days after sampling:

(1) a statistical analysis shall be performed on the groundwater monitoring results to determine whether there has been a statistically significant increase over background values at each monitoring well; and

(2) the groundwater monitoring results and the results of the statistical evaluation shall be submitted to the DEQ.

(b)Inter-well comparison. The groundwater quality of each chemical parameter or hazardous constituent at each monitoring well shall be compared to the background value of that constituent in the upgradient well, according to the specified statistical procedures and performance standards.

(c)Intra-well comparison. If a statistically significant increase over background values in any parameter or constituent is evident, the groundwater quality of each parameter or constituent at each monitoring well shall be compared to the background value of that parameter or constituent in the same well, according to the specified statistical procedures and performance standards.

(d)Statistically significant increase. If there is a statistically significant increase over background for one or more of the constituents at any monitoring well, the owner/operator:

(1) must notify the DEQ in writing within 14 days of the determination, and place a notice in the operating record indicating which constituents have shown statistically significant changes from background levels; and

(2) must establish an assessment monitoring program meeting the requirements of Part 9 of this Subchapter within 90 days of the determination, and have the assessment monitoring program approved by the DEQ; or

(3) may, during the 90-day development of an assessment monitoring program, demonstrate that a source other than the facility caused the contamination or that the statistically significant increase resulted from error in sampling, analysis, statistical evaluation, or natural variation in groundwater quality. A report documenting this demonstration shall be submitted to the DEQ for approval.

(A) If a successful demonstration is approved by the DEQ, detection monitoring shall continue.

(B) If at the end of the 90-day period, a successful demonstration is not made, the assessment monitoring program must be initiated.

(e)Extension allowed. Upon written request from the owner/operator, the DEQ may extend the 90-day deadline of (d)(3) of this Section for good cause shown.

(f)C&D landfills. In lieu of meeting the requirements of this Section, cumulative analysis data for the constituents in the approved groundwater monitoring program shall be submitted for each groundwater monitoring well at C&D landfills throughout the detection monitoring period. The data shall be submitted to the DEQ within 60 days of sampling and presented in tabular or graphical form for trend analysis.

Okla. Admin. Code § 252:515-9-74

Added at 20 Ok Reg 1151, eff 6-1-03