Significance. To attempt to evaluate the significance of the
          concentrations detected, we listed the number of VOCs with
          concentrations greater than 10 ug/1. The Wisconsin State Laboratory
          of Hygiene lists detection limits of less than 10 ug/l for most VOCs
          analyzed (Table 11). We selected 10 ug/l as an arbitrary cutoff to
          compare wells with low and high levels of VOCs.

          Waste Type. We looked for differences in the type, concentration or
          frequency of VOCs detected in wells at municipal and industrial
          landfills (Tables 2, 7 and 8).

          Indicator Parameters. We prepared a list of monitoring wells where
          VOCs were detected in groundwater for each landfill (Table 11). We
          then obtained historical data from the Bureau of Solid Waste
          Management's groundwater monitoring files. For each indicator
          parameter sampled, we indicated if current values were above
          background values or above the groundwater standards set by NR 140,
          Wis. Adm. Code. The Department is currently calculating PALs for
          indicator parameters at each landfill in the state. For landfills
          where indicator PALs have not yet been calculated, we compared the
          monitoring data to background values and made a qualitative judgment
          as to whether or not the data from the well were above background
          concentrations.

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