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1.0 Surface Water Monitoring Surface water samples were collected by Bryan A. Stirrat & Associates during the fourth quarter 2006 monitoring event from Littlejohns Creek at the upstream monitoring point (ASW -1) and downstream monitoring point (ASW -2). Surface water samples are scheduled to be analyzed quarterly for field parameters (pH, specific conductance, temperature, and turbidity) and monitoring parameters (bicarbonate, calcium, carbonate, chemical oxygen demand [COD], chloride, magnesium, nitrate, oil and grease, potassium, sodium, sulfate, total dissolved solids [TDS], total organic carbon [TOC], and volatile organic carbons [VOCs]) when surface water is present. The field and laboratory results provided by BC Laboratories, Inc. for the fourth quarter 2006 surface water monitoring event are summarized on Table 2.1. The historical surface water data are presented in Appendix A. The data are graphed on time series concentration plots, included in Appendix B. The concentration limits were calculated by Herst & Associates, Inc. using data collected through the fourth quarter 2006 monitoring event. Information on the development of the concentration limits can be found in the Fourth Quarter/Annual 1999 Monitoring Report, Austin Road Landfill prepared by CH2M Hill in January 2000 and is also available in Appendix C of this report. The statistical analysis calculations for surface water monitoring points are included in Appendix B. During the fourth quarter 2006 monitoring event, there were no constituents that exceeded their concentration limits at downstream surface water monitoring point ASW -2. Table 2.1 presents the VOC detections at surface water monitoring points during the fourth quarter 2006 monitoring event. Bromodichloromethane was detected at surface water monitoring points ASW -1 (0.23 ug/L) and ASW -2 (0.17 ug/L) at concentrations that were below the laboratory practical quantitation limit (PQL). Bromoform was detected at surface water monitoring point ASW -1 at a concentration of 1.0 ug/L, and at surface water monitoring point ASW -2 at a concentration (0.43 ug/L) below the laboratory PQL. Dibromochloromethane was detected at surface water monitoring point ASW -1 at a concentration of 0.86 ug/L, and at surface water monitoring point ASW -2 at a concentration of 0.51 ug/L. No VOCs detected at surface water monitoring points during the fourth quarter 2006 exhibit an increasing trend according to Sen's Slope analysis. The bromodichloromethane detections at ASW -1 and ASW -2 during the fourth quarter 2006 are the first detections of this constituent at surface water monitoring points. Historical data from the surface water monitoring points were evaluated for temporal trend using Sen's Slope trend analysis. Graphs of the Sen's Slope analyses for surface water monitoring points are included in Appendix B. Only field pH at ASW -2 exhibited a statistically significant upward trend for the fourth quarter 2006 monitoring event. The fourth quarter 2006 field pH value observed at ASW -2 (7.91) is comparable to values observed at that monitoring point consistently since January 2002, and is within the National Secondary Drinking Water Standard range of 6.5 — 8.5 Sen's Slope analysis identified decreasing trends in nitrate at ASW -2, field specific conductance at ASW -1, total dissolved solids at ASW -1 and ASW -2, and total organic carbon at ASW -1 and ASW -2. Site personnel report that soil cover has been placed over the waste material to prevent ponding of stormwater and to protect surface water. In addition, down drains and a perimeter ditch direct stormwater to a basin in the southwest corner of the site. Inspection and maintenance procedures for these stormwater control structures are provided in the site's Stormwater Pollution Prevention Plan, prepared by CH2M Hill and revised June 1997.