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Oil Exploration and Production Wastes Initiative Anal ses .Performed - The E&P waste samples collected were analyzed under the following parameters of study: pH; flash point; aquatic toxicity; metals; volatile organic compounds (VOCs); semi -volatile organic compounds (SVOCs); benzene; toluene; xylene (BTX); and total petroleum hydrocarbons (TPH). The number of samples analyzed was not the same for all tests. For example, the aquatic toxicity bioassay was conducted on one sample per wastestream, per facility. The number of sampled analyzed for VOCs and SVOCs was also smaller due to financial limitations, but was sufficient to support interpretive conclusions. Table 6 is a complete listing of all parameters of analysis, the number of samples analyzed for each wastestream, parameters of study, and number and percentages of samples with values below detection limits, where detection limits are applicable. Because each wastestream displayed variation in the type of analytes detected, subsequent tables list only detected analytes for the wastestreams presented. Tables 7, 9, 11, and 13 summarize results obtained for produced water, drilling waste, oily sludge, and foam treatment waste, respectively. The statistical calculations included for each parameter are mean, median, standard deviation, and percentages of samples with values above the regulatory threshold (RT), where RTs are applicable. The following approach was used for statistical calculations involving the data. For some tests (e.g., VOCs), the values obtained were below detection limits, or not detected (ND). According to standard DTSC procedure, for purposes of statistical calculations ND values are typically replaced with half the value of the detection limit (DL). This procedure assumes that if a contaminant was not detected, it is present in the sample at a concentration that is equal to half the lowest detectable concentration. Given the fact that DL is not a constant for each test but varies with the matrix for each individual sample, SCD chose to forgo the above procedure for practical reasons, and assume a value of 0 for all ND values. This method theoretically introduces a bias in the data in favor of the generator, by assuming that if a contaminant was not detected, is was not present in the sample in any concentration. However, for purposes of this project, it was determined that using 0 in lieu of half DL in statistical calculations would not affect the outcome of the study, because the concentration of the detected analytes in those samples was far below RT. It was noted that the data obtained from some analyses did not display a normal distribution, as indicated by the fact that the mean value was lower than the Statewide Compliance Division Ma 2002 -17-