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J 1 iiYq ,.wx1 - Mi -.ing Well MW-1 Installation Work Plan — - 630 N. California Street Stockton, California July 18, 2013 Page 2 soil was impacted by TPH-G, and to a lesser extent, by toluene, ethyl benzene, and xylenes . Metal analyses results were typical of background metals concentrations for this area of Stockton. Condor 1 recommended that the UST be removed. Condor prepared the Underground Storage Tank Removal Work Plan dated January 11 , 2012 and : I submitted the work plan to the City of Stockton Fire Department Fire Prevention Division (FPD) and the SJCEHD for approval along with an application for an underground storage tank removal permit. The work plan and permit application were approved in a letter from SJCEHD dated February 29, 2012 . Prior to implementation of the work plan is was determined that the close proximity of the tank to an active natural gas line, electrical line and the close proximity of the warehouse wall foundation would make full removal of the UST challenging. Condor recommended closure in-place in the Revised Underground n Storage Tank Removal Work Plan dated March 20, 2012 and submitted the work plan to the SJCEHD for l approval. --i On March 29, 2012, Condor and Jim Thorpe Oil excavated and exposed one single-walled steel UST and lassociated product piping at the Site. The location of the UST, and product piping are shown in Figure 3, Appendix A. A Condor representative was on Site to make field observations and collect soil samples following the removal activities. Jeffery Wong of the SJCEHD and Tim Salladay of the City Of Stockton ._I Fire Department Fire Prevention Division (FPD) were on Site to observe the UST closure activities and to specify soil sampling locations. Approval to abandon the UST in-place by filling it with a cement mixture was given by the FPD on the L permit inspection ticket and the SJCEHD in a letter dated March 29, 2012. The UST was filled with cement and abandoned in-place as approved. The UST abandonment was documented in the Underground Storage Tank Closure in Place and Soil Sampling Report, dated April 20, 2013 . r J 2.1 MONITORING WELL INSTALLATION FIELD PROCEDURES On � 2-inch diameter monitoring well will be installed. The monitoring well boring will be drilled using u an 8-mch .D. continuous-flight hollow-stem auger. Drilling activities will be performed under the supervision of a Condor geologist in accordance with the provisions of the SJCEHD permits. Drill l cuttings from the monitoring well boring will be logged in accordance with the Unified Soil Classification System (USCS). Descriptions of soil types encountered will be recorded on a geologic log. Soil samples N will be collected from the drill cuttings for the purposes of evaluating hydrocarbon contamination and to characterizing the cuttings for disposal. All down-hole drilling equipment will be steam-cleaned prior to 1 use. The drill cuttings and steam cleaning effluent will be placed in DOT-approved 55-gallon drums, sealed, labeled, and left on site. Disposal of hazardous materials, if any, will be the responsibility of the property owner. The monitoring well boring will be drilled to a depth of approximately 10 feet below the water table. It is anticipated that groundwater will be first enclZuntered at approximately 30 feet bgs. The monitoring well 1 will be constructed with 20 feet of 4-inch O.D., Schedule 40, 'flush-threaded, machine-slotted PVC screen (0.010-inch slot size). The screen wil e�from a depth of approximately 10 feet below the water table to 10 feet above the water table. A flush-threaded PVC bottom cap will be placed at the bottom of the screen section in the well. Blank PVC casing will be installed above the screens to the ground surface. A filter pack of #2/12 Monterey sand will be placed in the annular space to approximately two feet above the screens while the augers are in place. The depth of the sand in the annulus of the well will be monitored with a weighted tape measure while the sand is being placed and the augers are being gradually retracted to avoid bridging. To form a protective seal, approximately five feet of bentonite chips will be installed above the sand in the well. The bentonite chips will be installed as the augers are retracted. The ,1 i ] A too Al CONDOR d I �