Quality Assurance and Quality Control
Data Quality Assessment and Usability
The Remediation Standard Regulations, sections 22a-133-1 to 22a-133k-3 of the Regulations of Connecticut State Agencies (RSRs), include numeric criteria in Appendices A through F which are used to determine if a potential risk to human health or the environment may exist. The results of analyses performed on environmental media are used to determine if remediation is needed. Because of the nature of environmental media, limitations of analytical methods, characteristics of analytes, and human error, the results of environmental analysis may contain an element of uncertainty and in some cases may be significantly biased, and therefore may not be representative of the actual concentrations of the analytes in the environmental media. Thus, an evaluation of the quality of the analytical data in relation to its intended use is important in order for the environmental professional to make decisions which are supported by data of known and sufficient quality.
To assist responsible parties and environmental professionals in evaluating the quality of analytical data in relation to its intended use, the Department is providing the information below:
The guidance document titled Laboratory Quality Control Assurance and Quality Control, Data Quality Assessment and Data Usability Evaluation Guidance Document (DQA/DUE Guidance), effective May 2009 and revised December 2010 - There are many ways to evaluate the quality of analytical data in terms of precision, accuracy, representativeness, comparability, completeness and sensitivity in relation to the intended use of the data. Precision, accuracy, representativeness, comparability, completeness and sensitivity are collectively referred to as the PARCCS parameters. This guidance document describes a DEEP- accepted, two-step process for data evaluation. The first step in the process consists of an assessment of data quality. The second step is an evaluation to determine whether the data can be used to support the decisions that will be made using that data. Use of this guidance provides consistency in evaluation and presentation of data quality information that will facilitate review. If an alternative process is used, such a process should be documented in order to explain the thought process and may involve a commitment of significant resources to demonstrate that the data is of known and sufficient quality and is usable relative to its intended purpose.
- The guidance document titled Laboratory Quality Assurance Quality Control Reasonable Confidence Protocols, effective November 2007 and revised December 2010, provides information on laboratory quality control and quality control assurance and the Reasonable Confidence Protocols (RCPs). The RCPs are analytical procedures that include specific laboratory Quality Assurance and Quality Control (QA/QC) criteria that produce analytical data of known and documented quality. RCPs have been developed for twenty of the most commonly used analytical methods, and RCPs may be developed for other methods in the future. The RCPs are available below.
Final Discontinuation of the EPA 418.1 Method for Samples Collected After June 30, 2009
In the December 31, 2005 Federal Register, the EPA Office of Water proposed to revise 40 CFR 136 and withdraw all analytical methods that use Freon 113 as a solvent. The methods affected are 413.1, 413.2 and 418.1. The final rule was published in the March 12, 2007 Federal Register and the freon-based methods were withdrawn.
In an effort to help bring about the end of Freon use in Connecticut and to be consistent with Federal Law, the DEEP will not accept analytical data derived by EPA Method 418.1 for samples collected on or after June 30, 2009.
The Environmental Laboratory Certification Program of the Connecticut Department of Public Health (CTDPH) stopped offering certification for EPA Method 418.1 as of September 30, 2009 and after this deadline laboratories may not use EPA Method 418.1.
Data derived using the ETPH Method will continue to be accepted by the Department. In addition, the Department has provided further information regarding analytical methods used to characterize petroleum releases .