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GROUND -WATER MONITORING AND SAMPLING PROCFDURFS - Prior to sampling, the depth to water was measured in all monitoring; wells using an electronic immersion probe. All measurements were read to the nearest 0.01 foot. If free product was present, the depth to free product and tine depth to water were measured using an interface probe and an observation sample was collected with a clear teflon hailer for confirmation. No analytical samples were collected from monitoring wells containing more than 0.25 inch of free product. The monitoring wells were sampled on July 19, 1990. Prior to purging, each well was checked with a clear telon bailer in order to observe the possible presence of floating hydrocarbons. Purging was accomp'ished using a stainless steel or teflon bailer. The bailer was thoroughly cleaned prior to tach sampling using a trisodium phosphate solution followed by a 10% methylalcohol solution, and then rinsed twice with potable water. The wells were purged prior to sampling until pH, conductivity, and - temperature values stabilized. Generally, this resulted in the removal of approximately 3 to 5 well -` volumes of ground water from each well during the purging process. The water obtained from purging was placed in labeled 55 -gallon drums and stored on-site. The bailer line was replaced after each sampling. Samples recovered from each well were decanted into two appropriately prepared and labeled 40-m1 volatile organic analysis (VOA) bottles. A duplicate sample from MSV -303 was submitted for quality assurance. The sample bottles were immediately placed in an ice chest and maintained at 4°C until delivery to a State of California licensed laboratory. Routine chain -of -custody procedures were employed. A-1