A RANGE of events are being held across Edinburgh to mark this year’s Europe-wide Waste Reduction Week.Planned local actions include a waste reduction initiative by the Royal Bank of Scotland, where staff at its Gogarburn headquarters are being encouraged to make a pledge to reduce waste at work.

Betsy Reed, campaigns manager for Zero Waste Scotland, said: “European Week for Waste Reduction is a unique opportunity for everyone across Edinburgh to highlight their commitment to wasting less and recycling and reusing goods to both save ourselves money and reduce our carbon footprint.

“We can all play a part in helping Scotland become a place where we throw away less, reuse more and see waste as a resource. Together, we can truly lead the world in making Scotland a zero waste society.”

Running until November 28, the European Week for Waste Reduction 2010 aims to raise awareness of what individuals, organisations, community groups, education establishments and businesses can do to reduce waste by making simple changes to everyday behaviour.

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At the Landfill CQA blog we regularly receive requests for information from people who are developing landfills in industrializing nations where they are still largely unregulated.

They want to know what the essentials are for responsible landfill design and operation, and they have little inclination to read the detailed contents of much which is published in the developed nations guidance as it often seems unachievable within what they can afford to finance.

Also, with so much uncontrolled tipping they will often see themselves as unable to attract much waste anyway, if they are too far ahead of their competitors and have to make more than a fairly nominal charge to pay for environmental measures.

The message of this posting is that it is not in the long-term interests of the industry in these nations for operators to confine themselves to the absolute bare minimum of environmental protection and monitoring, and apply that slavishly everywhere.

The message must get home that unless operators can demonstrate that they are prepared to go further than the bare minimum required to show that their landfill practices are probably OK, where this actually matters they will lose all public trust.

If they are not prepared to go on to give a thorough demonstration that their practices are environmentally sound, then they will lose public support as local awareness of environmental quality develops.

History will then be repeated. Just as happened in the developed world within the last 20 years, they will have lost the trust of the local residents. Once that occurs, it will be difficult for their politicians, in a few years time as their national economies develop, to avoid the very prescriptive and not necessarily always essential, requirements of detailed legislative rules, By rules I mean those such as are in the EU Landfill Directive.

By “industrializing nations” we mean growing economies and rising prosperity, and in these conditions, as wealth grows, so will the environmental awareness of the population. A wealthier public will, in time, come to require the strictest imaginable conditions on landfill operations regardless of the circumstances, if they see the land despoiled by tips.

Draconian measures applied late, once much environmental damage has been done in any locality by poor landfill practices, will not be in the best interests of environmental protection. Politicians and lawyers are not good at making flexible regulations on complex environmental matters, and “one size fits all” usually means much miss-spent money, and effort; which if applied elsewhere could be far more beneficial to the health and welfare of the population.

There are plenty reasons why there should be debate within the industrializing nations about whether it is a better technique one way or another to allow wastes to degrade in highly contained, highly controlled sites, or whether instead the products of degradation should be allowed to be diluted and dispersed into the environment.

There can be some interesting technical debate, once environmental scientists and waste experts apply their minds to his. However, there should not be an unnecessary degree of polarisation on these issues. Some sites will always require full containment, others will not, depending on many local geographic, geological, and climatic factors, to name just a few.

There is no perfect containment site – a containment barrier always leaks to a lesser or greater degree, and will break down in time, and in reality we don’t know with any accuracy how long that time is likely to be.

The objective should be simply to keep the products of wastes in the landfill until they have degraded to a harmless state.

Equally, there is no such thing as a perfect dilute and disperse site. Instead there is a range of possibilities varying from a reasonable degree of containment to a rather low degree of containment, and the best type of containment to use in any particular situation will always depend upon a number of factors. Perhaps, the most important factor is the vulnerability of the surrounding environment.

The consideration of containment in big landfill sites versus less engineered dilute and disperse sites is perhaps the best example of the need for flexibility.

The issues for operators and regulators are not whether it is technically better to contain or technically better to dilute and disperse.

The real point is that whichever method is to be used, it must be demonstrated to be an environmentally sound way of managing the wastes that the facility is designed to cope with.

That means spending money on surveys and monitoring before the landfill site is developed. Quite probably what should be done is considerably in excess of what is currently required for regulatory purposes in most industrializing nations.

It means being prepared to concede that if it is not possible to demonstrate fully that containment is not needed, then containment should be required (while conversely accepting that containment is often not necessary).

This may not be welcome news to operators, but unless they heed this warning, the writing is on the wall.

If waste management operators, anywhere, truly want to build lasting businesses from operating environmentally sound landfills. If they aim for landfills to continue to be used as the low cost option, and the main way of waste management in their countries, then those in charge of landfills had better make sure – starting right now – that they are demonstrating that they are doing it properly.

In theory, there are 2 main kinds of modern landfills, the quarry-type below ground and the land raising-type. In the quarry or pit type the seeping groundwater and/or leachate must be piped to vertical shafts which are placed in the waste to keep the landfill dry.

Bauku telescopic well schematic

Circular pre-cast concrete wells can be specified which are raised with the waste with each “cell lift” but they are stiff and unable to withstand the inevitable movement of the waste as it settles around it.

So, what very often happens is that the shaft “shears” and the rings are pushed off-centre. As soon as this happens the necessary occasional man access need to maintain such wells has to cease for safety reasons, sooner or later the a pump becomes stuck in the well or it becomes silted, and maybe due to concerns about landfill gas intrusion from damaged joints during maintenance – it cannot be cleaned.

The sad fact follows that damaging effects on the shafts, usually due to the settlement in the waste commonly of up to almost 40 percent by depth, destroy almost every other type of shaft construction.

Therefore the German company Bauku developed the supposed telescopic shaft about twenty years back. Here the individual shaft elements are stacked above each other flexibly and can move with the waste as it settles.

Generally the shafts have a diameter of 2000 mm or more as maintenance must be carried out in the shafts. This is done by lowering breathing apparatus equipped specialist access contractor’s operatives down the shafts on wire ropes.

At the base of the shaft there are pumps for the transport of the seeping water as well as the entrances to the leachate pipes laid on the landfill liner, which need to be cleaned at regular intervals.

The Bauku telescopic shafts permit construction heights of almost one hundred m in the waste mass.

The dump site Merchernich at Cologne is a reference case to exemplify a very tough installation project.

These days, as Bauku state in their web site, HDPE “PROFILEEN telescopic shafts are found in all pit-type disposals of the Federal Republic Germany and with the adoption of the European (EU) standards and Construction Quality Assurance guidances more neighbouring nations are also thinking about this cutting edge product when planning their waste disposal (landfill) sites.

Telescopic shafts may also be integrated into the existing landfills later so that the standard of the many old rubbish heap sites can be improved significantly. Bauku also inform us at their web site, that such projects were carried out by us on a large scale in Britain in the last few years.

Landfill reclamation in varies guises is becoming more popular in many areas. The most common form of landfill reclamation seldom gets reported is such, and it comprises the removal of waste from brownfield sites where old landfills were present. These are usually quite small tips, and quite often due to there age there are very few problems in moving them, into new lined areas. Odours that might have caused distress to neighbours are gone and it is simply a matter of clearing and cleaning the land for development, removing a constraint which would otherwise have prevented redevelopment of the land This may be either due to regulatory requirements or risks of foundation settlement, and/or possible landfill gas present.

Reclamation can make sense economically too, for shallow and very old landfills. In addition to raising the land value once it can again be used for development the continuing liability to the owner of any old landfill will also be reduced by reclamation. It is easy to forget that old landfill sites must be monitored on a regular basis to make sure they are not causing pollution and are safe from such matters as gas migration iot nearby houses and factories.

The responsibility for this monitoring rests with the local Environmental Protection Authority (Environment Agency England and Wales) (EPA/EA) and landfill operators themselves. Landfill gas removal diminishes the potential for landfill contaminants to travel as a gas and dissolve into the groundwater. The regulatory aim is always to protect the public’s health and safety from the potential for the landfill gases to concentrate in enclosed areas where harmful vapours could be inhaled or an explosive atmosphere could occur.

Landfill mining also achieves landfill reclamation and is carried out for a slightly different purpose. Landfill mining is all about recovering valuable metals, producing high quality fertiliser and retrieving construction materials. In some nations carrying out this sort of reclamation is used to make available real-estate that was once considered lost forever.

However, concerns arise about the release of landfill gas and odours during reclamation works. Landfill gas has an unpleasant odour that can cause headaches or nausea. The odour, however, is more irritating than a hazard to health as it can contain carcinogenic compounds. Landfill gas escapes should be monitored at least quarterly at agreed points around the site perimeter to check for migration. A gas collection system may be installed that will enable gas to be sucked out of the wastes and collected and the collected gas be converted into energy.

During landfill reclamation it has been reported that waste material has proved much harder to sort, and the actual productivity has been much lower than originally estimated in feasibility studies.

Gas Plasma technology is being sold to carry out landfill reclamation projects in the US, and the most favoured technologies will not require manual sorting. In gas plasma plants, waste material is fed into a specially designed chamber and the intense heat of the plasma breaks down organic molecules (such as oil, solvents, and paint) into their elemental atoms. In a carefully controlled process, these atoms recombine into harmless gases such as carbon dioxide. This is why gas plasma is described as a mass destruction method.

Landfill reclamation can remediate groundwater contamination problems. Groundwater moves slowly and continuously through the open spaces in soil and rock below ground. If a landfill contaminates groundwater, a plume of contamination will occur. Groundwater, surface water, soils and sediments ons ite become contaminated. In most cases, and routinely, monitoring wells have to be provided around landfills in areas likely to detect leakage (e.g., downstream of the groundwater flow).

It is a sad fact that in many countries environmental contamination from landfills is entering watercourses and underground aquifers at alarming rates. Liner breaches, if indeed the landfill was even lined to start, are not uncommon. Landfill reclamation can at as stroke return land to normal uses especially housing, and by placing the existing waste in a new environmentally sound landfill also remove pollution.

Space is becoming the biggest issue. We have little enough space in most cities already, so we can hardly afford to effectively sterilise land above landfills forever. Space is even seen as becoming increasingly scarce throughout the United States, particularly in the more densely populated urban and coastal areas. Old closed landfills as time goes on will eventually take up massive tracts of land, and the use of that land will be very limited unless extension reclamation of these old landfills can be carried out.

Landfills nowadays each contain huge amounts of organic materials and hold a huge potential to pollute the local groundwater for generations in the containment systems upon which their design is based fail to function as intended.

The engineering of a landfill is no different to other engineered structures, in fact in many ways, especially due to its pollution potential it may be more important that it does not fail when compared to some other structures.

Landfill base liners are by nature buried once constructed and the opportunity to do repairs is extremely limited. Also, other structures may show visible signs of for example leakage, whereas a landfill may leak underground undetected for a long while until the damage is realised and by then there may be a substantial pollution plume already on its way underground to flow out into a river, or pollute a well or drinking water borehole.

The lining of a landfill is the foundation of a major civil engineering structure. If you think of a foundation of a tall building and how importantly engineers view the correct design of the piling for the foundations, you should then think of a landfill lining as equally if not more important.

Just as for the foundation of a multi-storey building great care is taken throughout the construction, the Engineer in charge of a landfill construction would be negligent if he did not require adequate checks to be made on all aspects throughout the design and installation of a landfill liner (or capping).

Carrying out all the necessary checking that the design is implemented and results in a properly built liner (or cap) in a methodical manner and without omissions and then to be able to show others subsequently that the quality of the materials used and the way they were placed will make a proper lining which is as the designer intended everywhere it is laid, is called Landfill Construction Quality Assurance (CQA).

CQA can only be applied once a competent design engineer has completed a design process which has resulted in a detailed specification for the materials to be used, and the thicknesses, depths and positions etc, of these materials when they are used.

This is what is called landfill geomembrane CQA, and it is normally carried out under the overall supervision of a client or purchaser’s professional representative (eg “Engineer”) who appoints an experienced CQA Engineer to carry out Construction Quality Control (CQC). The role of the CQC is the checker of the checker/tester which is usually the construction Contractor, assisted by an expert subcontracted testing laboratory.

The CQA Supervisor is best appointed to someone outside the construction Contractor’s organisation to ensure his/her independence.

Whilst geomembrane materials are relatively impermeable even when compared with low permeability clays, they will transmit a small amount of water even when perfectly installed.

The vapour transmission rates of the geomembrane materials used vary for different fluids, but for water they normally have a permeability in the region of 1×10^-15 m/sec. This sounds like a very low leakage rate, which of course it is, but for the large areas involved at most landfills the end result can be in the tens of cubic metres of leakage every day. This really does not matter in fact because during the design stage the lining designer will have ensured that this leakage will, by natural attenuation and dilution, cause minimal risk to the environment.

It is only if leakage rates increase substantially above this rate that problems will occur.

Unfortunately, if a landfill design is poorly carried out without a great deal of care being paid to construction quality (especially if only one thickness or one type of single barrier will be used), leakage can be hugely increased.

Just think how quickly a bath empties if you inadvertently knock the plug out while bathing!

In the realm of CQA, knocking the plug out without noticing when you did it would be called a lining defect.

It stands to reason therefore that leakage rates through a geomembrane are very significantly increased by the presence of even a few defects, and defects when present must be found and repaired before the job is finished.

In CQA plans in these defects are methodically identified and then as much as possible completely eliminated.

In CQA the defects that are usually identified and which the installer must prevent come from several sources, which typically take the form of:

• Defective geomembrane sheeting

• Defective seams resulting from inadequate seaming methods, or poorly trained installation staff

• Damage to the geomembrane during construction due to inappropriate subgrade materials or from construction plant or careless site personnel

• Damage to the geomembrane after burial due to inappropriate subgrade and/or cover materials, or due to excessive loading.

Does all his intensive CQA checking work?

The answer is yes, but it is never able to consistently always produce a perfect result – what human activity ever is?

It does appear to be worth doing, as US Studies (Giroud JP and Bonaparte R, Leakage through liners constructed with geomembranes, Geotextiles and Geomembranes. Vol 8, pp 27-67. 1989) have shown that the frequency of defects in geomembrane installations can be significantly reduced by the use of rigorous construction quality assurance.

However, what this also means is that unless the surrounding ground around a landfill is known to be a clay which is very impermeable and which itself will retain the leakage, or the surrounding geology comes somewhere close to this ideal, a composite liner (geomembrane (2mm HDPE say), plus a clay liner below it is necessary.

A combination of the best CQA practise and a composite liner will then be considered capable of achieving the intended and very essential protection of the locality from the pollution capability within any modern landfill.

( Article inspired by the paper by D Hall and P Marshall, Golder Associates in The Planning and Engineering of Landfills, Midland Geotechnical Society, 1991, UK)

The above is provided for educational and entertainment purposes only, and the reader must not rely on the content of this article to plan or design a landfill or the CQA measures applied.

Dense Asphaltic Concrete can be an extremely versatile product, suitable for many types of applications.

The ancient civilizations of Egypt, Babylon and Assyria all used bituminous lining materials and mortars for waterproofing and building, some more than 5,000 years ago, and many examples of their work remains intact even today.

More recently with the advances in hydraulic technology, asphalt has been shown to be an effective material for sealing Dams, Reservoirs, Canals, Water Catchments, Sea Defences, Coastal Groins, River banks and importantly for us - Landfill Sites.

WALO is a main UK supplier.

Current landfill site practice in response to the requirements of the Waste Regulations (UK) is to minimise leachate generation. To achieve this the operator fills the site, in a series of phases or cells which are raised as rapidly as input rates will allow to the top of the landfill, within small constrained areas, to reduce rainfall ingress.

When the operational cell is complete to restoration levels it is likely to be capped to prevent further ingress of rain water. Even the oldest waste at the bottom is therefore likely to be quite young and very little of degradation will have taken place to most of the waste.

So, under these circumstances significant settlement can then be expected, no matter how well the waste is compacted by the action of the site “compactor vehicles” (wheeled or sometimes tracked front-end shovels – often called “buldozers” by the public).

Settlement occurs due to the following mechanisms:-

i.The load on waste in the lower levels imposed by waste above it, particularly for deep sites, will be several times greater than that imposed during the initial compaction process using mechanical compactors. This will result in continued, physical compression compaction throughout the waste. This mechanism for settlement is likely to be predominant during filling and immediately following capping.
ii.The degradation process breaking down waste into a denser material.
iii.Volume reduction due to volatilisation (carbon emission in landfill gas etc). The production of gas will mean in very approximate terms a net mass loss of possibly 18% in total waste mass assuming 150m3 of landfill gas is in time extracted from each tonne of waste at 1.15kg/m3.
iv. Removal of leachate from lower levels of waste may also cause further settlement which is probably due to the pore water pressures being reduced.

Settlement is therefore predictable and must be catered for in the design of the gas abstraction system. It is the job of the landfill gas Engineer to assess the site “condition” and determine the potential for further settlement so that he can be satisfied a suitable design is proposed.

Determination of settlement rates and possible leachate levels is particularly pertinent to new sites and are important design parameters for the landfill gas Engineer to determine before he starts his system design.

If you need your landfill modelled for settlement, and settlement prediction provided, this is a service we provide regularly through our associated consultants. Just Contact us by email at news [at] landfillcqa.co.uk (Please replace [at] with @ ).

The use of a Geosynthetic Clay Liner (GCL) as the low permeability layer in landfill lining systems and restoration caps can provide a cost effective and readily Construction Quality Controlled alternative to natural clay. In fact this material may be the only option in regions where the local geology is such that no clay of suitable quality is available.

A GCL uses Sodium Bentonite, a dehydrated clay that has long been recognised as an ideal impermeable barrier material, and which will expand once in the soil to six or more times its initial volume.
Claymat is an example of this type of product which comprises a sandwich of bentonite between two layers of geotextile. The result is a thin, flexible (it arrives in rolls, clean, easily transported and installed) lining system. Finesse Claymat is as manufactured by ABG of Meltham, and there are a number of other manufacturers.

Layers of sand or fine gravel (150 to 300 mm) are often placed on top and/or below the GCL as specified by the landfill capping system designer to protect it from damage during installation or thereafter.

The GCL membranes on the market have been tested to provide both an excellent self-healing capability, and chemical resistance, and are accepted by most environmental regulators. A paper available from Thomas Telford Journals shows that permeability can be compromised if suitable treatment is not applied at overlaps, so clearly the CQA Engineer will need to take care about ensuring good site procedures on this matter. (See “Forensic analysis of excessive leakage from lagoons lined with a composite GCL”, At Thomas Telford Journals.)

Assessments of the environmental protection afforded by a landfill liner require that all underlying soil and geosynthetics components are considered in landfill contaminant migration assessments. The results described in a 2004 paper provides published data for laboratory GCL diffusion and sorption coefficients, required to perform contaminant migration assessments for five VOC contaminants commonly found in municipal solid waste leachate. Assessment of diffusion coefficients and clay-leachate compatibility assessment is also deemed necessary to ensure acceptable long-term performance. In fact GCL membranes were shown to give permeabilities generally significantly lower than those reported in the literature for compacted clay liner materials.

Pozidrain ground water drainage membrane is also often used in conjunction with a Geosynthetic Clay Liner as when laid above the GCL it reduces the hydraulic head and stress on the geomembrane and it also provides additional physical protection against puncture.

A significant number of landfill sites have already utilised the benefits of Geosynthetic Clay Liners and many use Pozidrain and equivalent products within these systems.

In the design of municipal landfill leachate collection systems, some state regulatory agencies require carbonate content of leachate collection system aggregate not to exceed 15 percent by weight. This requirement comes from a legitimate concern about the possibility of aggregate degradation, or loss of mass due to contact with leachate.

Most involved in landfill design and development will have experienced as a result, the fact that in some areas it is difficult to find carbonate free stone within an reasonably economic distance from the site. Many potential aggregate sources have been eliminated for supplying drainage material, due to this stipulation in the specification, but is it really warranted?

While leachate in MSW landfills is capable of dropping to pHs of 6.5, and sometimes 6, it rarely falls below this other than for short periods. This does not seem to be so low that problems would necessarily be serious, and if any of the carbonate dissolved from the stone, the amount would presumably be low as the reaction would be self limiting due to the dissolved carbonate caused by the reaction being bound to raise the pH. High pH will not erode the carbonate so the problem is corrected.

There is not a huge amount of research work on this that we have been able to find. We would be very interested to receive comments if our readers have sources to research on this matter which are more authoritative than the paper I am about to refer to.

The best paper we have found which sets out to by experimentation over a reasonably extended time period (in this case just under 6 months) to investigate whether carbonate drainage stone, when submerged in leachate, will suffer damage, is the following paper:

Suitability of Carbonate Aggregate in Land fill Leachate Collection Systems; Christopher G. Rubak, PE John,O. Starke, PE William D. Upman, PG M. Merrill Stevens, PhD: Presented to the Nineteenth International Madison Waste Conference, September 25-26 1996, Dept of Engineering Professional Development, University of Wisconsin – Madison.

This paper summarizes a research project which evaluated the suitability of a carbonate aggregate with a municipal solid waste leachate. The tests were conducted over a 20 week period using site specific landfill leachate and collection aggregate. Laboratory bench reactors were constructed to simulate landfill conditions with leachate flowing through carbonate aggregate.

The reactors consisted of 12-inch diameter plexiglass cylinders each charged with 80 pounds of carbonate aggregate. Leachate was then circulated through the reactors. An anaerobic environment was maintained in the reactors by applying 0.5 Atmosphere of CO2.

Fresh leachate was added to the reactors on a regular basis to maintain a constant concentration level during the test. Leachate samples were analyzed to determine the change in dissolved solids throughout the test period. Aggregate material was measured before and after the test to determine net mass change. Chemical equilibrium speciation modelling was also performed and compared to the bench test results.

On the face of it this experiment showed that there was no need for concern about carbonate deterioration even down to the exceptional pH 3.0 (exceptional for an MSW landfill under good regulatory control, built to good current standards).

However, the strange thing about the experiment to the writer is that the leachate used was changed on only, I think, 3 occasions; other than on these occasions the leachate was simply recirculated.

I would have preferred to see results which would ensure that the natural circumstances of a landfill were replicated more closely, and that would have meant allowing fresh leachate to pass through the system all the time.

The views of our readers are encouraged. There is a commenting facility available on the Blog Site to enable you to very easily let us know your views on this.

New MC3000 rolled out

Magpie Drilling has continued its expansion with a further MC3000 added to the drilling rig fleet. Following the increase in customer demand for deeper, larger diameter wells, with temporary and permanent steel casings, the need for increased power, higher torque, and superior depth capabilities are paramount.

The new machine has an extra rod in the carousel enabling it to drill 60m without any crew member ever having to handle a drill rod. A new design for the self extruding barrel has increased the power in which the pusher plate operates making the extrusion process faster and more efficient. More …