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City of Stockton A68108.OIB February 6, 1997 Page A-4 ... ■ Matrix spikes are analyzed in duplicate to validate the accuracy and precision of the method; and ... ■ During groundwater sampling, a travel blank sample consisting of organic-free water is prepared and containerized in the laboratory, transported to the site, and handled and transported in the same manner as the groundwater samples. A-5 Standard Operating Procedures for Using Photoionization Detector(PID) and/or Drager® Tubes: The PID is calibrated in accordance with the manufacture's recommendations prior to use in the field. Upon arrival at the project site, the PID is used to monitor background concentrations of organic vapors in the atmosphere at the site. The background concentrations are measured in a location upwind and removed as possible from sources of organic vapors on the site. When background concentrations of organic vapors register as "0.0" on the PID, subsequent readings of"0.0" registered from samples tested in the field are recorded as "ND" (not detected). When background concentrations of organic vapors register at some quantity above "0.0", subsequent readings registered from samples tested in the field at or below this value are recorded as "B/G" (background). The type of Drager® tubes used is dependant on the type of analyte which is suspected as being present on the project site (i.e. for gasoline product use the benzene tube, for diesel product use the petrol-hydrocarbon tube, etc.). Prior to use the tubes are examined to insure the shelf life expiration date has not expired and the tube has not been opened or damaged. Tubes are only used for one test. The Drager® Gas Detector Pump is used with Drager® tubes to insure accuracy. Prior to use the pump is examined to insure it is in proper operating condition. The tube is opened and inserted into the pump just prior to use. The pump is stroked the number of times required by the specific tube in use (i.e. 2 strokes for the petrol- hydrocarbon tube). After each stroke the pump is allowed to open to the full extent of the arrestor chain (10 to 20 seconds). If the analyte is present in the sample, the material within the tube will discolor. The extent of the discolored material corresponds to the concentration of the analyte present. Readings from the tube are recorded based upon the amount of discolored material read from the calibrated markings on the tube. In the event the discoloration should extend beyond one marking but not to the next, this is recorded as "greater than (>)" the lower value. (i.e. if the discoloration extends beyond 300 parts per million (ppm) but does not reach 500 ppm, this would be recorded as >300 ppm). The exception to this is when the discoloration reads less than the lowest value, this is recorded as "less than (<)" the lowest value on the tube. f After use tubes are disposed of as hazardous material because the contents are corrosive.