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MAY, 1 , 9 10. 300 71: 8:==F`j <br /> Groundwater Monitoring Well Installatiod <br /> i Three groundwater monilAaring wells(MW-5. MW-6 and MW-7) will be installed in the northeast <br /> portion of the facility to ritonitor the progress and effectiveness of the remedy. The wells will be <br /> constructed using 2-inch 5iarneter, schedule 40 PVC screen and casing to a total depth of about 20 feet. <br /> The wells wiiI be screened from a depth of about 5 to 20 feet. A detailed description of groundwater <br /> monitoring well installation, development and sampling procedures are contained in Appendix A. The <br /> three proposed wells and!existin&wells MW-I and MW-2 will be monitored monthly for depth to <br /> groundwater,dissolved oxygen, carbon dioxide redox potential, temperature and pH. In addition, wells <br /> MW-2,MW-5, MW-6 and MW-7 will be sampled monthly for TPH-G and BTEX compounds by EPA <br /> method 50301901518020,and for TPH-K,TPH-D, and TPH-MO by EPA method 351013015M. <br /> Vadose Zone Monitoring <br /> An oxygen soil probe manufactured by Datawrite Research Co. will be installed in a borehole located <br /> near the former sump at t:depth of about 6 to 7 feet. The concentration of oxygen will be recorded on a <br /> data logger every 4 hours and downloaded monthly. <br /> Soil samples will be colle1cted from the vadose zone near the former sump area on a monthly basis for the <br /> first three months and quarterly, thereafter. The samples will be collected from a point about 5 ft from a <br /> vadose zone ORC injection point at depths of 7 and 15 feet. The soil samples will be analyzed for <br /> TPH-G and BTEX compiaunds by EPA method 503019015/8020; TPH-K, TPH-D,'and TPH-MO by EPA <br /> method 351018015M, and redox potential. <br /> A detailed description oPthe field sampling methods and quality eontroUquality assurance protocol for <br /> this study is included in the field investigation Methods provided in Appendix A. Health and safety <br /> protocol for this project fare presented in Appendix B. <br /> DATA ANALYSIS ANI;t REPORTING <br /> A summary report will b,:prepared detailing the findings of this demonstration study. The report will <br /> include all field and labo,•atory analytical results, well construction details, and a discussion of the <br /> effectiveness of the ORC,at supplying oxygen to the subsurface and promoting biodegradation of the <br /> petmicum hydrocarbons that are present at the site. <br /> SCHEDULE <br /> ORC injection and well installation will proceed when PG&E receives regulatory approval of this <br /> workplan and obtains apliropriate drilling permits. The field work is presently scheduled to begin during <br /> 402331-9863 4-4 <br />