Monitoring the waste water of LEP

Along the LEP sites CERN is discharging water of differing quality and varying amounts into the local rivers. This wastewater is not only process water from different cooling circuits but also water that infiltrates into the LEP tunnel. The quality of the discharged wastewater has to conform to the local environmental legislation of our Host States and therefore has to be monitored constantly. The most difficult aspect regarding the wastewater concerns LEP Point 8 owing to an infiltration of crude oil (petroleum), which is naturally contained in the soil along octant 7-8 of the LEP tunnel. This paper will give a short summary of the modifications made to the oil/water separation unit at LEP Point 8. The aim was to obtain a satisfactory oil/water separation and to install a monitoring system for a permanent measurement of the amount of hydrocarbons in the wastewater.