Agenda - 01-20-1998 - 10a - Laserfiche WebLink

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' ~_ !1 MEMORANDUM TO: County Commissioners John Link, County Manager FROM: Paul Thames, PE, County Engineer DATE: January 12, 1998 SUBJECT: Landfill impacts on well water quality, sampling and analyses of landfill vicinity well water and costs of providing municipal water service as a community benefit As per the request of the County Manager, I have reviewed and evaluated a number of reports and other sources of information related to the above referenced subject(s). This information includes: 1) the October 1997 Hazen & Sawyer report on the cost of extending water and sewer utilities into the landfill vicinity; 2) the November 1997 Buxton Environmental ground water risk assessment report on landfill leachate; and 3) various memoranda and other materials provided by the Environmental Health Section of the Orange County Health Department related to well water quality testing in the landfill vicinity and throughout the County at large. In general, the Buxton landfill leachate report indicates that leachate will move towazd and eventually surface in three natural drainage channels that cross the landfill and border it on the north and south. The channels combine into one creek just east of the landfill and that creek drains away from the landfill to the east. The probability that leachate from the landfill could or would: a) cross under one or more drainage divides to move away from the landfill and toward other areas up-gradient from the drainage divides: or b) move vertically or sharply downwazd (as opposed to horizontally or laterally) into the deeper drinking water aquifers is extremely slight. Furthermore, ongoing drinking well water quality testing in the landfill vicinity by County Environmental Health staff has indicated that, except in one situation, tested wells in the area have shown any evidence of contamination by landfill leachate . Tests show that these wells have not been affected by water quality problems at any greater rate or degree than those in other azeas of the County. One landfill azea well, that which serves the Kirchner home on Millhouse Road, does show evidence of VOC (volatile organic compounds -chemicals such as solvents that are common constituents of landfill leachate) contamination at health risk levels. However, the Kirchner home is both up-gradient and more than 1000 feet north of the landfill. It is in an azea that, according to contemporary hydro-geological theory and experience, should not be affected by the movement of leachate from the landfill. There aze a number of other potential sources or causes for the VOC contamination of the Kirchner well. For instance, the Kirchner well may have been contaminated by the leaching of oil and solvents that were commonly sprayed on unpaved roads to control dust in yeazs past prior to the regulatory prohibition of the practice. In the event that local government or LOG policy makers wish to obtain additional information regarding the water quality in the landfill vicinity's drinking water wells, a more systematic and comprehensive well water sampling and analysis program can be undertaken. All or some statistically