The project's overall objective was to investigate the stability of selected contaminants in soil/sediment samples as a function of holding time prior to extraction. Contaminants of interest centered on SVOCs; particularly polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and pesticides, Cr(VI), and several heavy metals. Contaminant specific objectives were: 1. Determine if selected SVOC contaminant concentrations in soil/sediment changed with time when held in storage beyond their established extraction maximum holding times (MHTs) under current preservation techniques and at -20 deg C; 2. Determine if Cr(VI) concentrations change when held in storage beyond their established MHTs under current preservation techniques and at -20 deg C; 3. Determine if extracted Cr(VI) concentrations change when held beyond the analysis MHT (24-h) when held in the dark at room temperature (approx 20 deg C) or 4 deg C; 4. Determine if air-drying soil samples will adversely impact hot acid extractable heavy metal concentrations. Test soils/sediments from contaminated sites were identified, collected and homogenized prior to extraction by SW-846 methods. After homogenization, soil/sediment samples were stored under designated conditions and extracted at multiples of the current MHT (depending on the contaminant, multiples of MHT were between 0.5 and 12). Analyses of contaminant concentrations were performed in accordance with SW-846 methodologies. Results of these extractions were evaluated by a progression of four distinct analyses to elucidate possible decreases in concentration of an analyte (lines of evidence). First, the magnitude and variability of the concentration was used to suggest a level of the signal to noise ratio; second, a t-test of the H(sub 0):overall mean equal to or greater than the Day 0 mean was used to provide a level of relevance to observed change; third, a regression against time was used to estimate a rate of change; and fourth, a nonparametric upper and lower bound based on the Day 0 quartiles was used to provide an alternative measure of relevance to the potential change through time. Ultimately; however, linear regression analysis was utilized to estimate the time required to observe a specific percent change in the extractable concentration.

"EPA/600/R-05/124." "October 2005." "Www.epa.gov." "Contract no. 68-D-99-011, task order no. 18 (ORD-01-005)." Includes bibliographical references (pages 99-101).