The level or amount of QC necessary depends on the data quality objectives and should be decided by the ASR. QC pertains to sample collection, sample analysis, as well as data reporting. Laboratories should request sample QC information during preliminary discussions with the ASR.

In some cases, as when rapid turnaround and initial detection are the goal, reduced levels of QC may be acceptable. However, when quantitative results are needed to confirm that remediation efforts are successful, more extensive QC will be required. All relevant QC should be performed and documented as agreed upon by the ASR, PRL and the MSL.