Section 096-519-4 - Establishment of interim limits for the discharge of mercuryUsing the procedures in this Section, the department shall establish interim average and maximum effluent limits for the concentration of mercury discharged by each licensee identified pursuant to Section 1(C). These limits must be based upon and no less stringent statistically than past discharge levels as determined through testing required by Section 3.
A.Timing. The department shall establish interim effluent limits after the minimum number of tests required in Section 3 have been completed.B.Procedures. (1) Average limits. The department shall determine the interim average effluent limit for each licensee, as an average concentration, as follows. Using all valid test results for each licensee, a value equal to the standard error of the mean is added to the mean effluent concentration. The standard error of the mean is determined from the test results for each licensee by computing the standard deviation and dividing that value by the square root of the number of tests done. This value will be adjusted with a multiplier to reflect a 95% level of probability.(2) In the event that the interim average effluent limit as calculated above is less that 4.5 ng/L for an individual licensee, that licensee will be assigned an interim average effluent limit of 4.5 ng/L.(3) Maximum limits. The department shall determine the interim maximum effluent limit, as a maximum concentration in any sample, as follows. The interim average effluent limit as determined in (1) or (2) above shall be multiplied by a factor of 1.5 to establish the interim maximum effluent limit.(4) Additional information. Individual licensees may submit additional information for the department's consideration in setting interim effluent limits. Such information may include reductions in flow due to water conservation plans, seasonal variations and changes in levels of production. The department may adjust interim effluent limits accordingly if it determines that this information would significantly change the effluent variability as determined pursuant to this section.C.Notification. Upon determination of interim effluent limits, the commissioner shall notify the licensee in writing. 06- 096 C.M.R. ch. 519, § 4