The requirement for a waste producer totreat and characterise its waste in terms ofchemical composition and leachingbehaviour has had far reaching effects onthe analysis of site materials at the UK’sEnvironmental Labs. This characterisationrequires comparison of analytical resultswith waste acceptance criteria (WAC) todetermine the class of landfill able to takethe waste. This waste characterisation alsoapplies to the removal of anycontaminated land waste destined fordisposal at a landfill.

The regulations prescribe the leachingmethodologies that the laboratories mustfollow, with the previous, simple,contaminated land leaching methodsdeemed inappropriate.

The newly prescribed leaching methodshave impacted on the service offered bylaboratories. Whereas the turnaround timefor chemical analysis for remediation workhas reduced considerably over the past fewyears, with five days becoming the norm,some of the new leaching and percolationtests can take up to 10 weeks to complete.

The most common leaching methodsnow in use are the BS EN 12457-3, two-stage leaching and the up-flow percolationtest. Analysis of the resulting eluatesamples (we no longer call them leachateas that term is reserved for landfill sites)can then be compared with wasteacceptance criteria, to decide the class oflandfill site able to accept the waste.

Further leaching methods such as'Maximum Availability' and 'pH Dependencetests' can also be employed for particularwaste types, in addition to the 'DiffusionTank' and 'Compliance Leaching test' formonolithic wastes.

In all, there are now a plethora of newlaboratory testing procedures with analysistesting times far greater than thosepreviously offered.

Characterisation of WasteThe laboratory methods employed in thecharacterising waste to the new criteria(WAC) are dependent on the chemicalnature of the parameters being assessed.

In the main, organic parameters such as,total organic carbon (TOC), polycyclicaromatic hydrocarbons (PAHs),polychlorinated biphenyls (PCBs), benzene,toluene, ethyl benzene and xylenecompounds (BTEX) and mineral oil aredetermined as 'total' concentrations. Thatis, the samples are analysis 'as received'rather than first undergoing one of theprescribed leaching tests. The term ‘total’is slightly misleading here, since thechemical methods used for some of thegroups of compounds such as PAH onlyidentify a particular list of compounds (for

instance the USEPA group of 16 priorityPAHs), and should not be considered as atotal of every PAH that might be there. However, inorganic parameters such asmetals and anions are not analysed 'asreceived' but as the concentration that isleached under certain prescribedconditions, leading to an understanding ofboth the long term and short term leachingbehaviour.

These leaching tests enable predictionsof contaminant release to be made fordifferent conditions, such as different pHconditions or very low liquid to solid ratios.

Batch leaching test - BSEN 12457This is the recently introduced BritishStandard, Characterisation of waste-Leaching-Compliance test for leaching ofgranular waste materials and sludges.

Three variants of the leaching test areavailable to UK offering different liquid tosolid (L:S) ratios and solids content

These leaching methods generateeluates (not leachates, as this term isreserved for liquids generated on landfillsites) for analysis, enabling the assessmentof leachability under mild extractionconditions for waste disposal or materialreuse options.

The default version in the UK is theversion BSEN 12457-3, the two stageleaching method.

The method is only applicable to wastematerial and sludge having a dry mattercontent ratio of at least 33%. Wheresludges have a very low dried solidscontent and L:S ratio of 2:1 cannot beachieved, then the single stage BSEN12457-2 (L:S 10:1) may be undertaken.

These new leaching methods are notonly, more time consuming and thereforemore costly than the long standing InterimNRA leaching method, but also generatetwo water samples for analysis and hencetwice the cost for chemical analysis.

The cumulative result from the twostage leaching is the one that is used forcomparison with the WAC in order toidentify the most appropriate class oflandfill to accept the waste.

It should be remembered that thiseluate analysis covers mainly the inorganicparameters and that the more volatile andorganic parameters are analysed on thewaste itself.

Up-flow percolation test - prEN 14405 This method falls into the category of the'Basic characterisation' and is used toprovide information on short and longterm leaching behaviour of inorganicconstituents from granular waste. The

Characterising Landfill Waste -The Role of Lab Methodologies

The Landfill Regulations (2002),when fully implemented, havehad a major impact on the way that contaminated landremediation is carried out.

000 - WSP Environmental article 18/5/07 11:01 Page 2

waste is subjected to percolation withwater on a once through column system,with the subsequent test resultsestablishing the distinction betweendifferent release patterns of theconstituents.

A continuous vertical up-flow is usedso that the column of waste is alwayssaturated, the flow being between 15ml

and 60ml per hour. The flow rate of de-ionised water, weight of waste used andindividual test results enable conclusionsto be drawn on which components arerapidly being washed out and which arereleased under the influence of interactionwith the matrix.

The results of the analysis areexpressed as a function of L:S ratio, in

terms of both mg of the constituentsreleased per litre of eluate, and mg of theconstituents released cumulatively per kgof waste material. It is this cumulativemg/kg result that is then assessed againstthe WAC.

This is not a quick test to perform andit is not uncommon for the leachingprocess to take 30 days.

This can create something of adilemma for testing facilities. The actualnumber of samples that the new WACmight generate (particularly for testssuch as up-flow percolation) is somethingof an unknown quantity. Will there veryfew samples per year, will there behundreds, will there be thousands?

Each sample rig, of considerable costif automated, will only be able to carryout about 10 percolation tests per year(See Fig. 1)

In order to comply with WAC thesetests will be required as standard sinceJuly 2005. The initial estimates in the labindustry suggested that rapid uptake in2005 and 2006 would be followed by adecline in demand in 2007 onwards. Sofar this has not been the case, so much sothat certain Waste ManagementOperators have deemed it viable enoughto set up their own lab testing facilities.

One thing is certain, and that it is thatthe setting up of WAC testing rigs iscostly, but if laboratories do not take thegamble of providing ample capacity thenclients might find themselves beingadvised that there is a long waiting list foraccepting samples. The 30 to 40 day testperiod might not seem so long after all.

AUTHORDETAILS

Mike Cohen BA (Hons), CCHEM, M.R.S.C., M.C.I.W.E.M(Operations Manager, WSP Environmental Laboratories)Tel: 01159 739 220Email: wsplabinfo@wspgroup.com

Fig. 1 Upflow Percolation Rig

WSP Environmental Laboratories has over60 highly trained chemists, engineers andresearch scientists delivering high quality,state-of-the-art analytical services toconsultancy, site investigation and rem-ediation clients globally. WSP’s Lab facilityhas one of the most extensive ranges ofUKAS and MCERTS accredited tests in theindustry, and participates in several externalbenchmarking proficiency schemes inc-luding Aquacheck, CONTEST and RICE.

All it takes for groundwater sampling

Nijverheidsstraat 30, 6987 EM Giesbeek, The Netherlands

T +31 313 88 02 00 F +31 313 88 02 99

E info@eijkelkamp.comI www.eijkelkamp.com

The Answer Lies in the Soil!

There has always been aneed for an accurate,quick and convenientfield testing system forsoil in land sites. Hydro-carbons in abundance as waste are mostlyfound in ground where industry has operated –sometimes elsewhere fornot such noble reasons.Now for some years

PetroFLAG, available fromQUADREX Scientific (UK), has become

more widely used and accepted, operatingsuccessfully producing the desired results to meetthe latest environmental regulations for suspectcontaminated land.

The PetroFLAG system makes quantitativedeterminations in soils contaminated by a widerange of Hydrocarbons including Fuels,Lubricating Oils,Hydraulic Fluids, and greases etc.,by providing the user with instant results whilston-site, thus permitting immediate decisions forremedial action.

No special training is required to operate thePetroFLAG system. Using field calibrationstandards to achieve a very high degree ofaccuracy, the results are displayed on an LCD – allin around ten minutes from collecting the sample.All the reagents are environmentaly friendly andcan be disposed of as harmless laboratory waste.

The PetroFLAG system comes complete withreagents and all necessary ancilliary items,contained in a lightweight case which can beeasily carried, or transported to the site andoperated from the car boot.

Reports from the field have proven to be verypositive for its operation,accuracy andsatisfaction.

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