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�e*r <br /> URS <br /> March 29, 2013 <br /> Mr. James Barton,PG <br /> Engineering Geologist <br /> Regional Water Quality Control Board <br /> 11020 Sun Center Drive#200 <br /> Rancho Cordova, CA 95670 <br /> Subject: Workplan for Site Investigation Activities at the Newark Group,Inc., <br /> Petroleum Site,800 West Church Street, Stockton,CA <br /> Dear Mr. Barton: <br /> On behalf of The Newark Group, Inc., (Newark), URS Corporation (URS) has prepared <br /> this Workplan for Site Investigation Activities at 800 West Church Street in Stockton, <br /> California (the Site). A Site location map is shown on Figure 1. On January 30, 2013, <br /> URS submitted a Conceptual Site Model Report,(CSM) for the Site. In the letter from <br /> the Regional Water Quality Control Board (RWQCB) dated February 27, 2013, the <br /> RWQCB requested clarification and modifications to the CSM (Attachment A). To <br /> obtain the information necessary to update the CSM and to complete the recommended <br /> data gaps, URS has prepared this workplan to conduct an additional investigation of the <br /> three petroleum-impacted areas in the southern portion of the Site. <br /> The three investigation areas which are part of this investigation include the southwest <br /> corner- (boring B=7 area), the southeast corner (boring B-14 area), and the southeast <br /> corner(boring B-15 area). <br /> INTRODUCTION <br /> Purpose <br /> This workplan provides details of the planned field tasks and provides a rationale for <br /> performing each task. The primary objectives-of this project are to provide: <br /> • The collection of shallow(5 foot below ground surface [bgs]) soil gas samples <br /> from each of the three investigation areas to assess potential inhalation risks to <br /> future occupants of an overlying building (residence or commercial industrial <br /> building). <br /> • The collection of deep (10 feet bgs) soil gas samples from each of the three <br /> investigation areas to assess potential inhalation risks from vapor intrusion to <br /> indoor air. Deeper samples at approximately 10 feet bgs are required to ensure <br /> soil vapors have not been diluted with ambient air. <br /> • The collection of soil and groundwater samples to further assess the lateral extent <br /> of petroleum impacts in the B-15 investigation area in the southeast corner of the <br /> Site. Soil sample results will also be used to address potential health threats to <br /> URS Corporation <br /> 100 W.San Fernando St.,Suite 200 <br /> San Jose,CA 95113 <br /> Tel:408.297.9585 <br /> Fax:408.297.6962 <br />