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3. DATA QUALITY OBJECTIVES AND CRITERIA <br /> 3.1 Introduction <br /> Presented below is a discussion of the Data Quality Objectives (DQOs) and Data <br /> Quality Indicators (DQIs) for the project, along with the methods used to evaluate data <br /> quality. <br /> 3.2 Data Quality Obiectives <br /> DQOs are qualitative and quantitative statements that clarify the project objectives, <br /> specify the most appropriate type of data for the project decisions, determine the most <br /> appropriate conditions under which to collect data, and specify tolerable limits on <br /> decision errors. DQOs are based on the end uses of the data and are determined through <br /> a seven-step process as described in QA/G-4 [USEPA, 2006]. In addition to the project <br /> objectives, the DQOs specify data collection boundaries and limitations, the most <br /> appropriate type of data to collect, and the level of decision error that will be <br /> acceptable. <br /> The DQO process is a series of planning steps based on scientific methods that are <br /> designed to ensure that the type, quantity, and quality of environmental data used for <br /> decision-making are appropriate for the intended application. The DQO process <br /> provides a systematic approach to resolving issues that pertain to Site investigation and <br /> remediation [USEPA, 2006]. The DQOs were developed from discussions with the <br /> stakeholders, technical experts, quality assurance staff, laboratory representatives, and <br /> project management, as well as from all available historical data and information. The <br /> following sections describes the outcome of the seven-step DQO process. <br /> 3.2.1 Step 1 —State the Problem <br /> The purpose of the Site investigation is to identify potential alternate sources of PCE in <br /> groundwater and evaluate potential on-Site exposures via vapor intrusion (VI) to <br /> hypothetical future residents, current and future commercial/industrial workers, and <br /> future construction workers, consistent with the current and reasonably anticipated <br /> potential future land use at the Site. <br /> The constituents of concern for the Site are volatile organic compounds (VOCs), <br /> primarily PCE. Other VOCs will be monitored for VI and groundwater to assess Site <br /> conditions. <br /> Appendix C 5 <br />