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s Section No: 6 Page: 5 of 16 Revision No: 2.0 Date: January 15, 1994 Sampling Procedures 6.2.3 Integrated Samples continued Both natural and artificial lakes show variations of composition with both depth and horizontal location. However, under many conditions, neither total nor average results are especially significant; local variations more important. In such cases, examine samples separately rather than integrate them. Preparation of integrated samples usually requires special equipment to collect a sample from a known depth without contaminating it with overlying water. Knowledge of the I volume, movement, and composition of the various parts of the water being sampled usually is required. Thereforeq collecting integrated samples is a complicated and specialized process that cannot be described in detail. 6.3 Hazardous Waste Samples 6.3.1 Volatile Organics Standard 40 mL glass screw -cap VOA vials with Teflon -faced silicone septum may be used for both liquid and solid matrices. The vials and septum should be soap and water washed and rinsed with distilled deionized water. After thoroughly cleaning the vials and septum, they should be placed in a muffle furnace and dried at 150 C for approximately one hour. (Note: Do not heat the septum for extended periods of time, i.e., more than one hour, because the silicone begins to slowly degrade at 105 Q. When collecting the samples, liquids and solids should be introduced into the vials gently to reduce agitation which ndght drive off volatile compounds. Liquid samples should be poured into the vial without introducing any air bubbles within the vial as it is being filled. Should bubbling occur as a result of violent pouring, the sample must be poured out and the vial refilled. Each VOA vial should be filled until there is a meniscus over the lip of the vial. The screw-top lid with the septum (Teflon side toward the sample) should then be tightened onto the vial. After tightening the lid, the vial should be inverted and tapped to check for air bubbles. If there are any air bubbles present the sample must be retaken. Two VOA vials should be filled per sample location. VOA vials for samples with solid orsemi-solid (sludges) matrices should be completely filled as best as possible. a vials should be tapped slightly as they are filled to eliminate as much free air space as possible. Two vials should also be filled per sample location. VOA vials should be filled and labeled immediately at the point at which the sample is collected. They should NOT be filled near a running motor or any type of exhaust system because discharged fumes and vapors may contaminate the samples. The two vials from each sampling location should then be sealed in separate plastic bags to prevent cross - contamination between samples particularly if the sampled waste is suspected of containing high levels of volatile organics. (Activated carbon may also be included in the ` bags to prevent cross -contamination from highly contaminated samples). VOA samples may also be contaminated by diffusion of volatile organics through the septum during shipment and storage. To monitor possible contamination, a trip blank -prepared from distilled deionized water should be carried throughout the sampling, storage, and shipping process.