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AUG-15-1995 17:00 FROM TO 91-"'09478171-6-563541 P.04 <br /> �. ... <br /> Pools for Emergency Drinking 'dater <br /> Page 3 <br /> Sampling Qf PooLl�ater: <br /> L Five experienced Environmental Health Specialists within the Los <br /> Angeles County Department of health Services who carry out routine <br /> inspections of public swimming pools were asked to identify ten pools <br /> scheduled for routine inspection meeting the following criteria: <br /> 1) Pool is over 10,000 gallons. <br /> r' l 2) The pool equipment is in good working order; the pool is clean, clear, <br /> and otherwise well maintained. <br /> 3) The pool has no visible staining of the walls or side, such as might be <br /> due to copper or iron precipitation. <br /> L 4) The pool has a history of adequate disinfection with dry, liquid, or <br /> gas chlorine. <br /> L In order to sample a variety of pools, each inspector was further asked <br /> to choose the ten pools for sampling, in the following categories: <br /> a) at least 2 pools using chlorine gas as a disinfectant; <br /> b) at least 5 pools using a cyanuric acid disinfectant <br /> (trichloroisocyanuric acid or dichloroisocyanuric acid); <br /> c) at least 2 pools using liquid chlorine as a disinfectant; <br /> d) no two pools at the same address; <br /> e) at least one painted pool. <br /> Pools were sampled during October and November of 1993• At each pool, <br /> inspectors recorded the pool's size, condition, pH, free chlorine residual, <br /> concentration of total dissolved solids (TDS), and cyanuric acid level <br /> (determined by colorimetric method). The inspectors then collected pool <br /> water using a clean plastic bottle and a clean funnel rinsed three times in the <br /> pool water. The pool water was poured into several clean glass or Blastic <br /> containers, prepared for mineral and trace metal analyses. The collection <br /> bottles for lead and other heavy metal analyses had been pre-acidified with <br /> nitric acid according to EPA standard methods. <br /> At ten pools (two per inspector) duplicate quality control samples were <br /> taken for mineral analysis, and took additional water samples for analysis of <br /> volatile and semi-volatile organics. Two field blanks of distilled water were <br /> submitted for mineral analysis, and a travel blank for volatiles and semi- <br /> volatiles was submitted, All water samples were transported on ice, and <br /> delivered to the lab within 24 hours of collection. <br /> Inspectors measured the cyanuric acid level in an additional 50 pools <br /> which also met the selection criteria described above and which used cyanuric <br /> acid compounds as a disinfectant. For this measurement, inspectors used a <br /> field colorimetric method( '{'{REFERENCE"'°" O) with an estimated <br /> precision of about ("i•'•f 50% ???????) <br /> _ The primary analyses for minerals and trace metals were carried out in <br /> the Los Angeles County environmental toxicology lab. The ten duplicate <br /> quality control samples, which were also analyzed for volatiles and semi- <br /> volatile organics, were carried out by the California Department of Health <br /> Services laboratory, <br />