The installation is a landfill site licensed for the disposal of inert waste. It lies in a potentially sensitive location on the flood plain of the River Great Ouse, near Milton Keynes and it is therefore important to the client to ensure good environmental monitoring is undertaken. The site is divided into two sections, (the north western area and the south eastern area) by the River Great Ouse, which flows in a roughly south to north direction between the sites.
ESI Ltd was commissioned to provide a response to an Improvement Condition included in the PPC Permit that was issued for the site.
The Improvement Condition required borehole-specific control and trigger levels to be proposed for five down gradient groundwater monitoring boreholes, using at least 12 months of groundwater monitoring data.
Monitoring data were provided by the client and reviewed by ESI. Following inspection of the data ammoniacal nitrogen, chloride and sulphate were chosen as the appropriate parameters for which control and trigger levels should be set.
Control and trigger levels were derived based on statistical parameters calculated from the baseline groundwater chemistry observed at each of the site monitoring boreholes.
Where substances were not detected at a particular location the control and trigger levels were set at half the UK Drinking Water Standard (DWS) and the DWS, respectively.
ESI also provided a protocol to the client, outlining actions to be taken in the event that any Control or Trigger Level should be exceeded.