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STANDARD PROVISIONS AND REPORTING REQUIREMENTS, JANUARY 2012 -22- FOR 22 - FOR WASTE DISCHARGE REQUIREMENTS FOR DISCHARGES REGULATED BY SUBTITLE D AND/OR TITLE 27 be taken as the detection limit of the analytical method used (e.g., USEPA methods 8260 and 8270). 44.Alternate statistical procedures may be used for determining the significance of analytical results for common laboratory contaminants (i.e., methylene chloride, acetone, diethylhexyl phthalate, and di-n-octyl phthalate) if part of an approved water quality protection standard. Nevertheless, analytical results involving detection of these analytes in any background or downgradient sample shall be reported and flagged for easy reference by Central Valley Water Board staff. 45. Confirmation of Measurably Significant Evidence of a Release. Whenever a constituent is detected at a detection monitoring point at a concentration that exceeds the concentration limit from the water quality protection standard, the Discharger shall conduct verification sampling to confirm if the exceedance is due to a release or if it is a false -positive (unless previous monitoring has already confirmed a release for that constituent at that monitoring point). An exceedance of the concentration limit from the water quality protection standard is considered measurably significant evidence of a release that must be either confirmed or denied. There are two separate verification testing procedures: a. •. • Monitoring Specification• provides the procedure f• Ak that - detected in lessthan f' of the background samples such as non- IV b. Standard Monitoring Specification 1.47 provides the procedure for analytes that are detected in 10% or greater of the background samples such as naturally occurring constituents like chloride. 46. Verification Procedure for Analytes Detected in Less than 10% of Background Samples. The Discharger shall use the following non -statistical method for all analytes that are detected in less than 10% of the background samples. The non -statistical method shall be implemented as follows: a. Initial Determination of Measurably Significant Evidence of a Release. Identify each analyte in the current detection monitoring point sample that exceeds either its respective MDL or PQL, and for which a release has not been previously confirmed. The Discharger shall conclude that the exceedance provides a preliminary indication of a release or a change in the nature or extent of the release, at that monitoring point, if either. 1) The data contains two or more analytes that equal or exceed their respective MDLs; or Is 2) The data contains one or more analyte that equals or exceeds its PQL.