ARCHIVED REPORTS_REMOVAL ACTION COMPLETION REPORT

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Draft Removal Action Completion Report Neighborhood C, Mountain House,CA Page 1 I zones 14 through 19) by the analytical laboratory. The composite sample was analyzed for dieldrin by EPA Method 8081 A. Characterization samples were collected by inserting laboratory-supplied glass jars directly into soil. A stainless steel spoon or trowel was not used to place loose soil into the laboratory-supplied glass jars. Directly filling the jars eliminated the potential for cross-contamination and the need to decontaminate any tools. Each jar was labeled for sample identification and placed in a cooler chilled with ice. No equipment blank samples were necessary because no sampling equipment is used to collect waste characterization samples. Samples collected for waste characterization and analysis were labeled with prefix of a "WC" followed by the zone number followed by a suffix of a single letter designating the north, `B", or south, "A", section of each zone of the trench that the sample was collected from and then the depth below grade (WC IB-6'). Depth below grade was measured from the top of the trench lip to the existing depth of waste soil. The sample collected from the uppermost portion of the waste soil was labeled "AFG" for "at final grade". The zones were numbered sequentially from north to the south with Zone 1 nearest Mascot Boulevard (north end) and Zone 19 nearest Grant Line Road (south end). DeSilva established station numbers 100 feet apart that were numbered sequentially from south to the north(Figure 9,Appendix B). Waste characterization samples were collected from Zone 13 through Zone 1 on October 22, October 24, October 30, November 1, and November 11, 2013. Samples were labeled and placed in chilled coolers. Upon completion of sampling for each day, samples were transported under chain-of-custody procedures to Condor's Stockton Office and placed in a refrigerator maintained between 2 and 4 degrees Fahrenheit until remaining samples could be collected. The waste characterization samples collected on October 22, October 24 were not submitted to the analytical laboratory until November 8 because of delays in completion of encapsulation trench filling. This resulted in an exceedance of the sample hold time (14 days) for the October 22 and 24 samples. Additional samples were therefore collected in consultation with DTSC from the upper remaining 6 feet of the encapsulation trench on November 11, 2013 and were used for the 4:1 composite analysis for each Zone. Deeper samples could not be re-collected due to compaction of the waste soil. The delay and subsequent loss of samples for analysis resulted in a data gap with regard to the bottom 6 to 8 feet of the trench from Zone 13 northward. However, a 4:1 composite sample including samples collected October 30,November 1,and November 11 was analyzed within hold time from each of Zones 13 through 1. For Zones 14 through 19,the width of the encapsulation trench was increased 8 additional feet to include the landscape strip (centerline of Great Valley Parkway) and the entire southbound lanes of Great Valley Parkway for a total of 35 feet(Figure 8,Attachment A). 4.5 AIR SAMPLING Air sampling was conducted during work hours on each day of excavation activities in consultation with DTSC until the conclusion of dieldrin removal activities (18 total days). Two downwind and one upwind air sampling locations were used. The air sampling locations were collocated with the fenceline dust monitoring stations. Air sampling systems consisted of portable sampling pumps capable of sampling at 1-liter per minute, flexible tubing, and a sample container. The sampling pump provided by the laboratory was a Buck Libra Model L-4. The sampling pump instruction manual is included in Appendix D. The actual sampling rate was reduced to 0.5-liter per minute for 400 minutes to conform to analytical sampling method guidelines included in Method 5510 Issue 2, dated August 1994, included in Appendix D. The sampling guidelines specified a maximum sample volume of 200 liters. Therefore, the sampling rate was reduced in order to provide complete coverage of the entire work day. The sample container was