The Environment Agency has recently released guidance to help Waste Producers and Waste Management Operators categorise their waste streams and determine the appropriate class of landfill the waste is taken to.
Whilst the guidance includes waste classification and characterisation requirements, sampling schedules and testing requirements, and action to be taken should a sample fail testing, it is the changes to the Key Laboratory Process Steps (Appendix 3) that are of particular interest to the Laboratory Industry.
Key Laboratory Process Steps
Previous guidance for WAC leachate methodology recommended that a two stage leaching process be employed incorporating a Liquid:Soil (L:S) ratio of 2 1kg and an L:S of 8 1kg (BS EN 12457-3). Here, an amount of material is firstly leached with a volume of water so as to establish a L:S ratio of 2 1kg (moisture content corrected). Sample is mixed and leaching is allowed to proceed for 6 hours. The liquid portion is then decanted and filtered through a 0.45um filter before being passed for analysis. The remaining solid material then undergoes a second leaching step, this time at a L:S ratio of 8 1kg (or a total ratio of 10 1kg for both steps) for an 18 hour period. As before, the liquid portion is filtered through a 0.45um filter and analysed. Results are expressed as mg/kg (mg leached per kg of dry matter).
Appendix 3 of the new guidance now recommends that the Waste Acceptance Criteria leaching test be carried out in accordance with BS EN 12457-2. This is a single stage leaching method that uses an amount of material and leachant so as to establish a moisture content corrected L:S ratio of 10 1kg. Material is allowed to leach for 24 hours and the leachate filtered through a 0.45um filter (as in part 3) and passed for analysis. As before, results are expressed as mg/kg.
Single Stage Leachate Test
The move to a single stage leachate test should dramatically reduce both the amount of laboratory time spent preparing samples and the consumables used in the process. In particular, time spent performing the rate determining filtration steps will be significantly shorter allowing for quicker turnaround times.
Ultimately, this should mean data reaches the client quicker and at a reduced price!
Over the forthcoming months it is likely that a shift from the two stage leachate process (BS EN 12457 -3) to the single stage (BS EN 12457-2) process will occur as Waste Producers, Waste Managers and Landfill Operators begin to request this more cost effective alternative from their Laboratory suppliers.
For more information on the BS EN 12457-2 leachate process, or to request a competitive quotation, please contact your local laboratory or contact us online