work plan for soil remediation, sampling and analysis plan, site ...

OHM RemediationServices Corp. SAMPLING AND ANALYSIS PLANThe accuracy criteria is determined by calculating the standard deviation of seven or morepercent recovery values and setting the upper and lower control limits using the followingequations:Where:p = Average percent recoverySD = Standard deviationUpper control limit = p + 3SDLower control limit = p - 3SDAfter the standard deviation, for the seven or more samples has been calculated, the accuracycontrol limits will be used to determine if the analysis is out of control. This is done bychecking the results against the control limits. If any values are above the upper control limitor below the lower control limit, all sample results after the last qualifying accuracy samplemust be repeated or discarded. If seven consecutive values fall below the lower control limit,new limits must be calculated using the new accuracy check values. If the values fall betweenthe upper and lower limits, then conditions are reported as “within limits.”6.1.1 Recovery ControlRecovery control is necessary to determine if the sample matrix is interfering with theconstituent being analyzed. A minimum 5 percent of samples will be recovery check samples(matrix spikes). Samples involving different types of matrices must have at least one recoverycheck for each type.Control limits will be determined for each matrix, determining the deviation for seven or morepercent recovery values.6.2 PrecisionDuplicate and replicate samples analyzed by the laboratory assess the precision of the samplingeffort Control limits for duplicate/replicate RPDs are listed in Appendix A, Table A-2. Oncea sufficient amount of replicate data becomes available, field precision control charts areconstructed similar to the laboratory precision charts. For any given concentration, the meanand the standard deviation(s) of the replicates are calculated. The mean is the centerline of thecontrol chart Data from each sample set are pooled with the previous sample sets to generatecontrol and warning limits for the next set. Warning and control limits for water samples areset at +Zs and &3s, respectively. Control limits for solid samples are more liberally establisheddue to matrix heterogeneity. Data outside any control limit are subject to QA review.OHM Project 16487SAP Sampling and Analysis Plan May 1995Jnfommtion herein ia proprietary and confidential and to be wed or released to others only with explicit written permission of OHM RanediationScrvicca Corp.6-2