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

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S ,~ ~ d valid sampling (subject to the permission and cooperation of the owners) of the water supply wells in the neighborhoods adjacent to or near the landfill, can be subjected to an initial screening for VOC contamination. The azeas or neighborhoods screened may also be limited to those which lie in the direction of leachate plume movement indicated in the Buxton landfill leachate report. Regazdless of the sampling program, the initial screening process can be undertaken by the County's Environmental Health staff (with the concurrence of the Orange County Boazd of Health) or by some private sector consultant with water sampling expertise and laboratory water quality analysis capabilities. Those wells which show no VOC contamination, even if the presence of iron or naturally occurring metals aze detected, can be reasonably assumed to be currently unaffected by any constituent of landfill reachate. In the event that one or more of the wells tested show evidence of VOC contamination, the presence of one or more VOC compounds may indicate contamination by landfill leachate. As there aze other sources of VOC contamination, including very localized contamination of well water through surface water infiltration and inflow into improperly constructed wells, all- wells showing VOC contamination would be cazefully re-examined. Older wells or those for which no accurate well construction information exists could also be examined by means of inserting a video camera into the well. New water samples from contaminated wells would be acquired and tested both to confirm the VOC results of the initial screening test and to look for the presence of tracer materials or elements such as boron and detergents or other indicators. Presence of these tracer materials or indicators, which are not naturally occurring in this azea but aze commonly associated with highly mobile components of landfill leachate, would be a strong indication of contamination by landfill leachate. If landfill leachate contamination were confirmed in one or more wells, other wells located in a pattern radiating outwazd from the landfill and the contaminated well(s) would be tested to try to define the size and direction of the leachate plume. The information could then be used to help determine: 1) if and where an extension of a municipal water distribution network would be justified to overcome landfill related water quality problems: and 2) if associated costs could be chazged as landfill operation related expenses. The cost of the testing program, if undertaken by County Environmental Health staff with lab work for the initial screening provided by the state environmental health lab, is estimated to be approximately $30,000. The cost of a similaz testing program undertaken by private consultants and labs is estimated to be approximately $70,000. There aze a number of caveats that aze applicable to the strategy outlined above. The primary assumption that provides for the savings in the County Environmental Health controlled testing program is that there aze very few, if any, existing wells that aze contaminated with landfill leachate. Each of the initial screening tests conducted by the state lab will cost in the $100 to $150 range. Follow-up testing by a private lab capable of detecting boron or other indicators will cost as much as $400 to $500 per sample. Video inspection of wells also costs approximately $500 per well. If more than ten percent of the wells screened (assuming 140 wells initially screened) require additional testing or inspection, the final costs would rise very quickly. It is assumed that a private firm would chazge $500 each for sampling and testing each well and that there would be no initial screening process as the boron and other indicators would be tested for in the initial analyses. There aze three other potential caveats that have been cited by Ron Holdway, Director of the County's Environmental Health Section. The first is that there is a conceivable liability involved in an invasive inspection (video) of wells where there is a potential for actual or perceived damage to the well or its piping, wiring or pump. The second is that participation in the testing and inspection process by the Environmental Health Section could result in some sort of enforcement action related to observed septic tank system malfunctions at any housing or