In this report some vital data on landfills, used in Sweden’s greenhouse gas inventory to the UNFCCC, are controlled according to current guidelines. Quality aspects of historic surveys on deposited wastes are considered and compared over time. Plant specific data on recovered methane gas from landfills have been scanned into a database, which has been used as a tool for quality control.

Despite of some minor differences, the historic quantities of deposited wastes seem to be consistently estimated. There seem to be no systematic differences between the surveys with data on deposited waste amounts, but the variability in the earliest surveys is probably greater.

Data on recovered methane are accurate in general, since they mainly depend on sold energy; information that is well documented at the plants. Some unexplained deviations are however identified, when comparing the plant specific values over time. In some cases, it may be possible to increase the quality of the data by renewed contacts with the respondents. Much data were however collected some years back in time, which probably will make a systematic revision of the data unrealistic. A revision of a few values would probably only have minor impacts on the total amount of recovered methane. In the future, the quality of data input could be improved, by immediate consistency checks with older data. The collected data could be stored in a waste database, such as DIA (a database created within the project Data om hushållsavfall), to simplify this procedure.