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GENERAL COMMENT ON VOLUME 2 (QUALITY ASSURANCE PROJECT PLAN) 1. The Comprehensive Quality Assurance Project Plan (QAPP) references the EPA QA/G-4, 1994c, Guidance for the Data Quality Objectives Process (DQOs) , to answer the question statement: "All analytical data received from multiple laboratories for various field tasks at DDJC-Sharpe/Tracy need to be of appropriate data quality and comparability, and can be used for decision making. " According to the EPA, the purpose of using the DQO process is to "determine the type, quantity, and quality of data needed to support Agency [EPA] decisions." The decision process should include, in the following order: (1) Scoping, (2) Data Quality Objectives, (3) Sampling and Analysis Plan (which includes FSP, QAPP, HSP) , (4) Sampling and Analysis, (5) Data Quality Assessment (which includes assessment of sample locations, quantity, and type) and (6) Decision. However, it appears that the DQO process in the QAPP was used to determine data comparability between the laboratories the DOD proposes to use, and not as a tool to determine the ,quantity and type of samples to be collected. It is common for projects to focus on laboratory error when reviewing data quality, however, the laboratory data error is usually minuscule in comparison to sampling error and overall project decision errors. Please include a statement that DQOs will be evaluated in each draft site-specific work plan submitted for EPA review. SPECIFIC COMMENTS ON VOLUME 2 (QUALITY ASSURANCE PROJECT PLAN) 1. Table 4-1, Page 4-3: This table includes the QAPP Data Quality Objectives (DQO) . The DQO process is a seven step process as shown in Figure 4-1 (Page 4-2) . However, the table and figure are not consistent: Table 4-1 is missing the step "Define the boundaries of the program" which is listed in Figure 4-1. If some of the steps in the DQO process will not or cannot be followed (e.g. , because they don't apply) , please note this in the QAPP and provide the rationale for omitting a particular DQO process step. 2. Table 3-11, Page 3-15: This table includes the required reporting limits for Method 8280A. The water reporting limit for 2,3, 7, 8-TCDD is listed as 3.8 ug/l (0.01 ug/1) 10.01 ug/l is the target reporting limit for applicable methods] . However, the National and California Primary Maximum Contaminant Level for Drinking Water (MCL) is 0.00003 ug/1. Since the MCL is much lower than the water reporting limit for 2,3, 7, 8- TCDD (and lower than even the target detection limit) , a detection automatically signifies an MCL exceedance. Therefore, please discuss in the QAPP the limitation of the analytical method in determining MCL exceedances for 2,3,7,8-TCDD. 2