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I - Quarterly Report - Third Quarter 2005 FIRE STATION#2 ' 110 West Sonora Street, Stockton, California ' 1.0. INTRODUCTION At the request of the City of Stockton,Advanced GeoEnvironmental, Inc (AGE) has prepared this I report for corrective action activities conducted at 110 West Sonora Street, Stockton,California(the site) The scope of work included advancement and sampling of one shallow soil boring, operation of an ozone injection air-sparging system and performance of a quarterly ground water monitoring Ievent The location of the site and Its surroundings are illustrated on Figure 1 Structures and well locations associated with the site are depicted on Figure 2 The site history, Including a description ' of previous work performed at the site and a basic site conceptual model,are detailed in Appendix A 1 1 INITIAL SITE REMEDIATION A soil vapor extraction/in-situ air sparging (SVEIIAS) system was installed during August and September 2001 Soil vapor monitoring and sampling events,groundwater sampling events,and the results of laboratory analysis of the samples collected have been documented in subsequent quarterly monitoring reports The operation of the IAS system has produced only minor volatilization of the � . dissolved hydrocarbons in the deep ground water well samples at the site(VW-2d),but has reduced the dissolved hydrocarbon concentration in the shallow well samples (MW-1 and VW-1)as well as the concentrations of hydrocarbons in the soil vapor extraction (SVE) influent to below detection I levels Subsequently, AGE proposed to augment the IAS system with a low-flow ozone generator in a work plan dated 28 January 2003 12 AUGMENTED SITE REMEDIATION An ozone air spargmg system was installed 01 July 2003 on-site, utilizing the existing in-situ air sparging(IAS)system wells IAS-1 through IAS-3 and currently microsparge well OZA In total,the ozone system has operated approximately 8,800 hours and has been operational except for core part replacements (air compressor) 2.0. PROCEDURES All field work was performed in accordance with Central Valley Regional Water Quality Control Board(CVRWQCB)guidelines for the investigation of underground storage tank(UST)sites Ozone sparging was conducted in accordance with procedures outlined in the AGE-prepared Ozone ` Spargrng and Additional Monitoring Well Installation Work Plan,dated 07 October 2002 Soil and ground water sampling was conducted in accordance with procedures outlined in the AGE-prepared • Additional Site Assessment Work Plan,dated 02 May 2005 and approved by the San Joaquin County Advanced CcoEnvironmcatai,Inc