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aquifer to determine if impacted groundwater is migrating downward. The following methods and protocol will be employed during this phase of the characterization: • All the borings will be continuously logged. • The soil will be screened in the field with a PID. • A discrete grab groundwater sample will be taken at the top of the uppermost groundwater in each of the shallow boring. • These samples will be submitted to a state certified laboratory for 24-hour analysis of TPH as gasoline,BTEX, and MTBE. • If the grab groundwater results indicate low levels of petroleum hydrocarbons(i.e., benzene less than 100 ug/L),then the boreholes will be considered for conversion to / monitoring wells. If the grab groundwater results contain elevated levels of petroleum "t hydrocarbons,then additional boreholes will be drilled further downgradient until the �N grab groundwater results indicate the vicinity of the plume fringe. J • Upon determining the approximate location of the downgradient plume fringe,PHS will be consulted and a shallow monitoring well will be installed that is screened across the water table. Based on the extent of the downgradient plume,one additional shallow monitoring well may be proposed if downgradient lateral coverage is not sufficiently provided by one well. • One to two deep wells will be installed in the vicinity of the downgradient shallow well. These deep well(s)will be screened at a similar depth interval as MW-11D. • Wells installed during this phase of work will be developed using the standard protocol used for previously installed wells at the property. Subtask 3 Laboratory Analysis Grab groundwater samples from Activity II will be submitted to a state certified laboratory. The samples will be analyzed for TPH as gasoline,BTEX,and MTBE.The grab groundwater samples will be analyzed in a 24-hour turnaround time period. Subtask 4 Reporting The report for this phase of work will be combined with Activity III.The report contents are described under Activity III. _ Activity III - Installation of Upgradient Monitoring Well Based on the findings of Activity I and existing upgradient well data,the value and necessity of conducting Activity III will be revisited. If necessary, the purpose of Activity III will be to install an upgradient well in the vicinity of the known release that intersects the current water table;the existing upgradient wells do not intersect the current water table. If it is determined that Activity III is necessary, then this activity will be conducted at the same time as Activity II using similar protocols. 6