WORK PLANS - Laserfiche WebLink

Home Browse Search

I Precision is the degree of mutual agreement between or among independent measurements of a similar property (standard deviation [SD] or relative percent difference [RPD]). This indicator relates to the analysis of duplicate laboratory or field samples. Completeness is expressed as the data actually obtained compared to amount that was expected to have been obtained. Due to,'a variety of circumstances, sometimes not all samples collected „ can be analyzed. The percent of completed analyses required will depend on the sampling design and data use. Expectation of completeness should be higher the fewer the number of samples taken per event or site. Representativeness is the expression of the degree to which data accurately and precisely represent a characteristic of an'environmental condition or a population. It relates both to the area of interest and to the method of taking the individual sample. The idea of representativeness should be incorporated into discussions of sampling design. The representativeness of data will be ensured by the use of established field and laboratory procedures and their consistent application. Comparability expresses the confidence with which one data set can be compared to another. The use of standard, published methods allows the data to be compared to data from other projects; using the same methods throughout allows for comparison of data within a project. The comparability of all data collected will be assisted by reporting each data type in consistent units. All depths, elevations, and distances will be presented in English units. Chemical data will be reported in parts per billion (micrograms per liter [ug/1]) for water samples and parts per billion } (micrograms per kilogram [ug/kg]) or parts per million (milligrams per kilogram [mg/kg]) for soil, wood, and sediment samples. 6 Data Quality Indicators: Accuracy, precision, and completeness goals for the major chemical analyses to be performed on samples collected for the Weber Block site are presented in Table t 5-1. The actual precision and accuracy of the chemical data collected will be calculated by the laboratory at the conclusion of.the field work. If the data do not meet the goals prescribed in Table 5-1, they will be retained; but so noted in any reports they are represented. The precision of data reported at or near detection limits may in many cases be low (i.e., relative percent difference (RPD) exceeds Table 5-1 goals), even though the°data-may be acceptable. For example, duplicate values of 0.2 parts per billion and 0.9 ppb would result in an "unacceptable" RPD of 127 percent. Therefore, the precision goals in Table 5-1 are stated as appropriate for results at least 10 times greater'I'than the detection limits. 5.3 Data Management Data collected will be appropriately identified in the Phase 2 Investigation Report and 10% of the samples may be validated, if necessary. Where test data have been reduced, the method of reduction will be described in the text of such report. Entry of any data to computer databases will be checked by cross reading hard copy data files with the data in its. original form. { Validation of data obtained form field measurements will'be performed by checking procedures nA362IOMSAMwebsap2mp5 WEBER':BLOCK (Area 9) Sampling and Analysis Plan 0 Page 11