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<br />URBAN AND INDUSTRIAL POLLUTION <br /> <br />Synthetic pollutants are the byproduct of urban living, <br />and industrial and agricultural production. Urban <br />pollution comes from leaking tanks and sewers, <br />industrial waste discharges, commercial facilities, <br />failed septic systems, leaking sewer lines and old <br />and current landfills. Sometimes pollutants are <br />filtered out. Other times, water is polluted in the <br />process of being delivered to the tap. <br /> <br />One source of pollution is leaking underground fuel <br />tanks, many of them from neighborhood gas stations. <br />The leaking fuel contains a number of chemicals, <br />some of which are associated with cancer, and in <br />some places the tanks have polluted groundwater. <br />Cleanup of the tanks, contaminated soil and the <br />groundwater beneath them in some cases has been <br />paid for by a special tax on fuels. The issue is shaped <br />by two recent controversies. <br /> <br />1) A 1995 study conducted by Lawrence Livermore <br />National Laboratory found that of the 28,000 leaking <br />underground fuel tank cases in California, drinking <br />water wells had been contaminated at only 136 sites. <br />The report concluded that natural degradation and <br />consumption of contaminants by soil organisms <br />would in many cases eliminate the pollutants in soil <br />and groundwater. The State Board, in a move <br />criticized by some, recommended to the Regional <br />Water Quality Control Boards that no additional <br />cleanup be pertormed at many sites where only the <br />soil was contaminated by leaked fuel. <br /> <br />2) An effort to reduce air pollution has resulted in <br />groundwater pollution. Methyl tertiary butyl ether <br />(MTBE) is a legally required ingredient in gasoline <br />that helps fuel to burn cleaner. MTBE has helped <br />clean up the state's air by reducing ozone levels but <br />it has since been discovered in many groundwater <br />wells and surface water reservoirs, leading some <br />to push for tighter restrictions and more study of its <br />health effects and others to call for banning its use <br />altogether. MTBE is considered a possible human <br />carcinogen, but scientists are still studying how it <br />moves through the environment and the potential <br />consequences to human health. Its turpentine-like <br />taste and odor in groundwater can be detected at <br />fairly low levels. <br /> <br />Fuel ingredients and solvents are among a group of <br />pollutants known as volatile organic compounds <br />(VaCs). Some of fhe worsf vac pollution - in the <br />San Gabriel and San Fernando valleys in southern <br />California and around Sacramento in northern <br /> <br /> <br /> <br />California - is the product of military bases and the <br />private industries that supported defense efforts. As <br />more military bases are closed, how quickly the <br />contamination can be cleaned up is key to how <br />smoothly some bases can be converted to civilian <br />uses. Most of these areas <br />are being cleaned up under <br />the supervision of EPA's <br />Supertund program. <br /> <br />Some VOCs are associated <br />with California's "clean" high- <br />tech industries. In 1981, sol- <br />vents leaking from under- <br />ground tanks associated with <br />Santa Clara Valley computer <br />manufacturing -facilities were <br />found in aquifers tapped for <br />drinking water. Ultimately <br />more than 100 contaminated <br />sites were found, The discov- <br />ery contributed to action by <br />the Legislature in 1983 to <br />create a comprehensive pro- <br />gram of permitting and in- <br />specting underground tanks. <br /> <br />Garbage dumps or landfills <br />also are a concern as gar- <br />bage and potentially toxic <br />household chemicals leach <br />into today's wafer supply. <br />California has more than <br />2,300 active and closed land- <br />fills. Many of them were <br />constructed before 1984, <br />when comprehensive permitting regulations were <br />enacted. Regulations now prohibit the public from <br />putting toxic materials into municipal landfills. <br />Regulations also require constructing landfills to <br />prevent leaching, and comprehensive monitoring to <br />watch for leaks so that action can be taken if it leaks. <br />State and local agencies also have become more <br />involved in recent years in reviewing plans for new <br />landfills or landfill expansions out of an interest in <br />protecting groundwater. Nevertheless, in some <br />cases, leaks have occurred at facilities specifically <br />designed to contain toxic materials. <br /> <br />To deall Ill' ('mIlWllinalC'd <br />~u.oUl/(hnl1e1; many eilic>s <br />and indllstrics f/(Il'C turned <br />to air strippinx systems. <br />a!Jo\'(', which call remm'e <br />l'o/atile organic chemicals <br />jinmmilliolls of gallo/ls <br />(~r l\'(/ter e(lch dllY. <br /> <br />Under the 1996 Safe Drinking Water Act (SDWA) <br />amendments, some groundwafer-supplied domes- <br />tic water systems will have to disinfect the water to <br />kill potentially harmful microorganisms - viruses, <br /> <br />15 <br />