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Minutes - Regular Meeting Solid Waste Advisory Board March 5 , 2009 Approved April 2, 2009 When looking at a topographic map it shows the Old Field watershed, which means when it rains and when there is more rain than soaks into the ground, the runoff goes into the Old Field watershed to where it joins New Hope Creek . Precipitation that falls outside the dotted line [referring to map in handout/ presentation, on the County web site] goes the other way . The State requires that there be a network of monitoring wells around the perimeter of any landfill to find out if that landfill is contaminating the ground . The nitoring program supplies different types of information, direction of groundwater mo groundwater flow, the velocity of the groundwater, and the chemistry . Groundwater does not flow as fast as most people believe . The old landfill consists of a number of wells . One of which is uphill, or upgradient, of the landfill . There is a suite of wells located on the down hill/ downgradient side of the landfill . Every six months the county takes [water] samples from all the wells and runs a chemical analysis on them . In looking at the maps of the groundwater topography, it does not matter where you are if it is at the old landfill [meaning the old closed segment on the north side] or the new landfill [meaning the lined section on the south side] , [water] is flowing from the west end of the property to the east end . They converge at a point along Millhouse Road and it is moving about six meters per year . What are we looking for in the groundwater ? Regulations from EPA says there are 213 constituents consisting of heavy metals and mostly manmade organic compounds . Our concerns are with those constituents that have exceeded their NC Groundwater Quality Standard . These are extremely conservative and very protective of human health . Most of them are less and sometimes very much lower than drinking water standards established by EPA . We don' t see too many of the 213, but the ones we see are important. We are also looking at measuring very small amounts of stuff . The unit of measure is parts per billion. The equivalent would be one kernel of corn in a silo full of corn 45 feet high, 16 feet in diameter . We are seeing mercury . It is difficult to determine the significance . One reason is that metals occur naturally . There are five organic constituents that occur with some regularity in different wells and exceed the standard in micrograms per liter, (parts per billion) - benzene, 1 ,4- dichlorobenzene, cis-1 ,2- dichloroethene, trichloroethylene, vinyl chloride . We look at this data over time . Benzene for example decreased over time to below the drinking water standard and went back up then came down. In the well closest to the waste, it was highest and decreased as it approached the property line . You' re more likely to get a bigger dose of benzene pumping gasoline at the gas station than from this groundwater . Ford explains the flozv of tzvo more of these chemicals and their presence in comparison to the drinking zvater standards and ground zvater standards . A lot of this study has to do with looking at these chemicals and their concentrations around the landfill . The next step is who might be at risk of the groundwater going in 2