ARCHIVED REPORTS XR0009009 - Laserfiche WebLink

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i • C A M B R I A transport to a State of California certified laboratory for analyses A standard two week turn-around time will be requested for laboratory results The piezometers will be drilled using hollow-stem auger drilling equipment Each boring will be drilled to approximately ten feet below first encountered groundwater Based on the quarterly monitoring results, groundwater is approximately 47 to 50 feet below grade (fbg) The i piezometers will be constructed using two-inch Schedule 40 PVC well casing The screen interval will be approximately five feet above and ten feet below first encountered groundwater for each well The sandpack will be placed from the bottom of the well up to two feet above the top of the well screen, followed by a two-foot thick bentonite seal and cement grout to grade I Actual well construction details will be based on field conditions and static water levels during drilling Each well will be secured with a locking cap under a traffic-rated well box Chemical Analyses: Selected soil samples will be analyzed for TPHg and BTEX by EPA Method 8015MI8021 or equivalent and fuel oxygenates (MTBE, ethyl tertiary butyl ether, tertiary butanol, di-isopropyl ether, and tertiary amyl methyl ether)by EPA Method 8260 • Wellhead Survey Activities: Following piezometer installation, a licensed surveyor will survey wellhead elevations relative to mean sea level and the well locations relative to latitude and longitude Aquifer Pump Test: To conductT5-day m med tion and determine aquifer hydraulic characteristics, Cambria propos s quife mp test The test will utilize proposed well MW-4 as an extraction point Grr will be extracted using a Grundfos model SQE-15 electric submersible pump The extracted groundwater will be temporarily stored in a 20,000- gallon Baker tank A liquid-level switch mounted in the Baker tank will be connected to the groundwater pump to prevent tank overflow Based on the extraction rate, vacuum trucks will be scheduled to periodically remove water from the Baker tank in order to maintain storage capacity and continuous extraction The extracted groundwater will be transported to the Martinez Refining Company in Martinez,California for recycling Groundwater samples will be collected from the extraction well prior to extraction, each day of pump test, and at the end of pump test Interim remediation effectiveness will be evaluated by determining MTBE mass removal, the MTBE concentration trend over the course of the pump test,and the MTBE concentration trend from subsequent quarterly groundwater sampling events i 0955 3