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C <br />C <br />C' <br />11 <br />u <br />n <br />C <br />�I <br />u <br />n <br />u <br />positive displacement (bladder) pump tubing are cleaned by heating the tubing overnight at 120°C <br />with a low -flow, inert air source. <br />Once the bladder pump is cleaned and reassembled, a pump blank is obtained by pumping <br />organic -free water through the bladder pump assembly. The pump effluent is sampled and <br />analyzed by USEPA Method 601. The pump effluent analysis results must be below the method <br />reporting limit for each parameter before the pump is taken to the site for use. <br />During field sampling, equipment surfaces that are placed in the well or contact groundwater are <br />steam cleaned with deionized water before the next well is purged or sampled. <br />Water -level and Total Well -depth Measurements <br />Immediately before a monitoring well is purged, the water level and total well depth are measured <br />using an electric sounder as described above. The electric sounder is decontaminated by rinsing with <br />deionized water after each use. <br />vin II 2= <br />- <br />Standing water in the casing and gravel pack is purged from the monitoring well using a dedicated <br />Well Wizard® bladder pump, pneumatic displacement pump, or Teflon® bailer, prior to collecting <br />samples. Monitoring wells are purged according to the protocol presented in Figure A-1. In most <br />cases, the amount of water purged before sampling is equal to or greater than three casing volumes. In <br />cases where the monitoring well is evacuated to dryness prior to the removal of three casing volumes, <br />due to the low yield of the well, the well is allowed to recharge for up to 24 hours. Samples are taken <br />as soon as the monitoring well has recharged to a level sufficient for sample collection. If insufficient <br />water has recharged after 24 hours, the monitoring well is recorded as dry for the sampling event. <br />Purged water is disposed to the ground surface around the well. <br />Groundwater purged from wells is discharged to the ground near the well but away from surface <br />water drainage features. Discharging to the ground surface is considered common practice where <br />the groundwater is non-toxic. <br />A Teflon bailer or bladder pump is the only equipment acceptable for well sampling. Unless <br />otherwise described, the sample containers for all parameters are filled, filtered as required, and <br />capped. <br />Volatile Organic Compounds (VOCs) <br />When samples for volatile organic analysis are collected with a bladder pump, the pump flow is <br />regulated to approximately 100 milliliters per minute to minimize pump effluent turbulence and <br />aeration. Glass bottles of at least 40 milliliters volume and fitted with Teflon -lined septa are used in <br />Groundwater Monitoring A-3 Department of Public Works/Solid Waste <br />County of San Joaquin <br />