USING ROUND ROBINS AS A TOOL FOR EVALUATING LABORATORY QUALITY

The Rock River Water Reclamation District monitors approximately 90 Significant Industrial Users, SIUs, for conventional and toxic pollutants. These industrial users may report the District's data to meet the self-monitoring requirements in the General Pretreatment Regulations, 40 CFR 403. In addition to using District data, about 20% of the SIUs also monitor their wastewater discharges at in-house or contract laboratories.The pretreatment regulations require POTWs to review and evaluate data before accepting it for compliance determination. Over the years, the District has occasionally questioned data reported by industry. The data may not compare favorably with analyses performed in the District laboratory or the data may not appear representative of the industries wastewater stream. And, of course, it was not unusual for an industry to object when the District questioned their data.The District needed an objective way to determine whether industries were submitting reliable self-monitoring data. Staff performed an investigative round robin in April 2001. Evaluation of the round robin results indicated 25% of the participating laboratories submitted problematic metals data. After considering several ways to effectively monitor data from outside laboratories, the District developed an ordinance requiring all industries submitting selfmonitoring data to participate in semi-annual round robins. Labs with acceptable round robin results may continue to submit data. Labs with unacceptable results cannot submit data until they successfully demonstrate compliance through analysis of lab standards or passing the next round robin. As a result of these new procedures, the District has fewer discrepancies between its data and that of outside labs, industrial labs are motivated to improve their analysis procedures, and the District has objective criteria for evaluating industrial data.