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. .. j. F :4 GROUND-WATER MONITORING AND SAMPLING PROCEDURES _ Prior to sampling, the dcpth to water was measured in all monitoring well, using an ceectronic immersion probe. All measurements were read to the nearest 0.01 foot. If free product was present,the depth to free product and the depth to water was measured using an interface probe and an observation sample was ectlected with a clear teflon bailer for confirmation. No analytical samples were collected from monitoring wells containing more than 0.25-inch free product. 'Fite monitoring wells were sampled on June 19 and 20, 1989. Prior tour ing, each well was P B sampled with a clear teflon bailer in order to observe the possible presence of flaming hydrocarbons. Purging was accomplished using a stainless steel bailer. The bailer was thoroughly cleaned prior to each sampling using a trisodium phosphate solution followed by a I0010 methylaEcohol solation,and then rinsed with water. The wells were purged prior to sampling until pH and conductivity values stabilized. Generally, this resulted in the removal of approximately 3 1�5 well volumes of ground water from each well. The water obtained from purging was placed i in labeled 55-gallon drums and stored on-site. TFe sailer line was replaced after each sampling. t�. Samples recovered from each well were decanted into two 40-m1 appropriately labeled, volatile organic analysis(VOA)bottles,one of which is the duplicate quality cortrcl sample. A travel blank and a duplicate travel blank(numbered as MW-26)and a duplicate sample from MW-23 were also i A submitted for quality assurance. The sample bottles were immediately placed in an ice chest and maintained at 4°C for delivery co a State of California licensed laboratory. Routine chain-of- custody procedures were employed. c, IL A-1 Du Pont Environmental Services j