Groundwater Monitoring (GM) is the crucial element of landfill supervisory measures. The German Guideline WÜ98 defines the mandatory scope of GM.
The Working Group of the Federal States on Waste (LAGA) adopted the guideline “WÜ98” for GM. It defines two control setups with (i) a fixed set of parameter (FSP) and (ii) a set of parameter which is adapted to specific conditions (SSP) of the landfill (LF).
The frequency of the obligatory measurements depends on the presence of a base liner system:
- LF without liner: FSP: 2 years; SSP: 3 months.
- LF in accordance to the EU landfill directive: FSP: 5 years; SSP: 6 months.
Parameters of FSP and SSP:
On-site: Colour, smell, turbidity, T, pH, eC, solved O2, H2S, water level (at start + end), pump down time, suction rate.
Laboratory: pH, eC, Na, K, Mg, Ca, NO3, NH4, SO4, Cl, acid capacity at pH=4.3/8.2, TOC.
Parameters of FSP:
N, F, Fe, Mn, B, CrVI, cyanide, hydrocarbon-index, AOX, PAK, phenol index. As screen-ing: common anions, metals, phenols, cresols, highly volatile halogenic hydrocarbon. Tests with aquatic organism: daphnia or luminous bacteria test.
The results of the analysis are evaluated and compared with the background values of the adjacent groundwater. Parameter which show higher levels close to the LF than the background value have to be tested more frequently in the control setup SSP.
For every LF specific threshold values are set by the authority, which consider local geohydrology conditions and threshold values of other ordinances in a statistical approach. If threshold values are exceeded, protection measures may have to be conducted.
adequate number of groundwater monitoring wells.
The costs for one measurement SSP are between 400 and 700 €.
Evidence of success
The practice provides a standardized groundwater monitoring programme. The evalua-tion of the results is similar from location to location since background values are utilized for evaluation and used as trigger value to detect potential impacts of the landfill. The monitoring setups contain the most important parameters for the groundwater observation. It is possible to respond flexibly to different pollution situations.
In areas with a complex geo-hydrological environment the monitoring setup has to be adapted. When evaluating the results, it should be considered that threshold values may set too strict as the specific local conditions may change. Not every exceeding denotes a hazard.
Potential for learning or transfer
Most landfills in the EU have no base liner system. Leachates from the waste of landfills and, in particular, landfills with hazardous waste can severely pollute the groundwater. Therefore a long-term groundwater monitoring is necessary even in the after-care phase. For the landfill operator and authorities it is important to plan the time-scale of the after-care phase. In this connection the evaluation of measured values on the basis of the corresponding threshold values is crucial. The end of the after-care phase can just be declared when there is no threat that threshold valued may be exceeded.
According to the EU landfill directive groundwater monitoring is compulsory. However, no further framework for frequency, parameters or evaluation of the results is included.
The practice can be used particularly for groundwater monitoring of landfills without a base liner system. In these cases groundwater pollution is common. A limitation for the scope of this practice is not necessary.
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