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