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I BLAINE TECH SERVICES INCA DIEGO <br /> S N JOSE SACRAMENTO LOS ANGELES SAN <br /> In wells Initially suspected of containing SPH, the MMC detector Is the sole Instrument used to <br /> collect water and SPH levels In the well <br /> Wells containing SPH at a measured thickness of 0 02 feet or greater are not sampled <br />' TOTAL WELL DEPTH <br /> Total well depths (TD) are measured Initially at all wells new to the monitoring program and at <br /> least annually afterwards with an Industry standard electronic water level Indicator graduated in <br /> Increments of hundredths of a foot <br /> All DTW, SPH and TD measurements are recorded on the Well Gauging Data sheet <br /> 5. DETERMINING PURGE 1 NO-PURGE STATUS <br /> The Scope of Work (SOW) for each event at each site indicates the status of each well to be <br /> sampled as Purge, No-Purge or No-Purge Contingent as determined by the URS Project <br /> Manager Wells labeled as Purge are sampled using Purge methodology Wells labeled as No- <br /> Purge are sampled using No-Purge methodology Well labeled as No-Purge Contingent are <br /> sampled using either Purge or No-Purge methodology depending on the relationship between <br /> the water level In the well on that particular day and the top of the well screen If calculations <br />' show that the well screen Is submerged, the well Is sampled using Purge methodology If the <br /> well screen Is exposed, the well is sampled using No-Purge methodology <br /> I� 6. PURGE METHODOLOGY <br /> PURGE VOLUME CALCULATION <br /> In wells requiring purging prior to sampling, minimum purge volumes are calculated anew by <br /> multiplying the height of the water column by the appropriate casing diameter based volumetric <br /> conversion factor Volumetric conversion factors are shown below <br /> 193 0 04 3" 037 6° 1 47 <br /> 2" 016 4" 065 OTHER radius2 (0 163) <br />' Minimum purge volumes are never less than three case volumes <br /> SELECTING PURGE METHOD <br />' Well purging devices are selected by the Sampling Technician based of the well diameter and <br /> the total volume to be evacuated <br /> For purges of less than 5 gallons In all size wells, the water Is typically removed by hand balling <br />' with a disposable or Teflon bailer Maximum purging rate Is approximately 1 gallon per minute <br /> (gpm) <br />' STANDARD OPERATING PROCEDURES—BP/ARCO NORTHERN CALIFORNIA Page 3 <br />