SITE INFORMATION AND CORRESPONDENCE_FILE 2

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Chapin Brothers Page 3 1766 Monte Diablo May 21, 2009 Stockton, CA 8/12/93 The date of the EHD letter documenting notification of three feet of free product being found in MW1 and requiring removal of the free product. 8-9/93 Free product was removed from MW1 on 8/16/93, 8/19/93 and 9/2/93. The amount had been reduced to 1.2 inches. 12/27-29/93 Dates that monitoring wells MW2, MW3, MW4 and vapor well VW1 (borings B2 — B5) were installed. 3/29-30/94 Borings, B6 through B6, were drilled during this time. 05/12/94 A pump test was performed on MW1 on this date. 06/10/94 A vapor extraction test was conducted and vapor wells VW2, VW3 and VW4 were installed on this date. VW1 could not be used because of poor vacuum so the test was performed on VW3. 7/22/94 The date of Problem Assessment Report that details the work performed during March through June 1994 and recommends using vapor extraction with dewatering or air sparging. 1/3-5/95 Five borings were drilled during this time. P1 was completed as VE1 and air sparge observation well ASO3. P2 was completed as ASO1. P3 was completed as VE 3 and ASO2. P4 was completed as VE2. Air sparge well AS1 was installed. 01/14/95 A vapor extraction and air sparge test was conducted on this date. 03/95 The date of the Final Remedial Plan (FRP) that details the January 1995 work and proposes vapor extraction and air sparging for remediation. 08/18/95 The date of the EHD letter approving the FRP. 03/07/96 Vapor extraction wells VE5 and VE6 and monitoring well MW5 were installed on this date. 06/21/96 The date of the report on the March 1996 work. 08/96 Start up of the vapor extraction system was attempted during this time, but continuous operation wasn't successful. 04/01/97 The date operation of the vapor extraction system began. 04/19/97 The date vapor extraction well VW7 and air sparge wells IAS2 through IAS7 were installed. 04/24/97 The date monitoring well MW6 was installed.