A busy year for Victoria

A busy year for Victoria

A year on, Inside Waste was curious about the progress, if any, and changes that the minister had made, particularly around its proposed e-waste to landfill ban, waste to energy – interest seems to be ramping up in the state – and planning and integration.

We posed a number of questions to D’Ambrosio and here’s what her spokesperson had to say. Read more

Leading the sector into the digital era

Leading the sector into the digital era

Inside Waste caught up with the AMCS team – CEO Jimmy Martin, sales manager Australia and New Zealand Gerard Kissane, and former ASP CEO Terry Daley who will stay on for 18 months to consult on marketing and sales – to find out what the company has in store for Australia.

Who is AMCS?

Headquartered in Limerick, Ireland, AMCS offers an end-to-end suite of software and vehicle technology to the waste and resource recovery sector. Its 350-man team works across the globe, with offices in the UK, central Europe, the US, Australia, and New Zealand. Read more

Sustainable Insights: Growing Australia's waste and resource recovery industry…it's happening

Sustainable Insights: Growing Australia’s waste and resource recovery industry…it’s happening

Commercially it makes sense and as the sector grows nationally it will drive changes in community behaviour and understanding, boost economic development and jobs growth.

Unless we tackle waste reduction from every angle we won’t make the most of our potential.

The industry’s spreading its wings

A 2012 Australian Bureau of Statistics study found 98 per cent of Australian households took part in some form of recycling or reuse of household items. Read more

WMAA landfill conference: exploring the use of trommel fines as landfill cover

WMAA landfill conference: exploring the use of trommel fines as landfill cover

Speaking at the Waste Management Association of Australia’s 2017 Australian Landfill and Transfer Station conference at the end of March, Mockinya Consulting director Paul Lightbody told delegates the project started as a means to find a use for trommel fines produced at a refuse-derived fuel facility in Adelaide.

The plant, which was established in 2006, processed some 150,000 tonnes of construction and demolition and commercial and industrial waste a year to produce an engineered fuel.

The feedstock it receives is screened, goes through a size reduction process, and is then separated to produce process engineered fuel, aggregates, fines, as well as a small amount of residual waste that is landfilled.

“Two streams come out of this process – one’s a coarser stream and the other’s a finer stream,” Lightbody said.

“Parts of the equation that framed this project was to look at what these materials were, how they could be used, which characteristics might be important, and whether these materials and residuals could become a resource.”

At the moment, there is simply no local market for the oversized fines (12-40mm) and heavy fines (12mm minus).

Typically, these fines, which Lightbody said are “studied extensively”, are composed of inert mineralogical materials including plaster/gyprock (85.6%), organic inclusions (12.13%), glass (1.54%), hard plastic (0.17%), light plastic (0.02%), other miscellaneous materials (0.42%) and an almost negligible percentage of metal and foam.

Key considerations

Because of the fines’ composition, there were characteristics that Lightbody needed to evaluate.

“The issues for the use of these materials on landfill as cover were potential flammability particularly because there were visible inclusions of plastics. There was also potential for it to generate odour and further contribute to methane emissions in the landfill because of the organic fraction. It also needed to be suitable from a chemical composition perspective and we already were pretty satisfied about that in the quality of the material,” Lightbody explained.

Additionally, under the SA EPA licence requirements, landfill cover must be a “soil” and not a waste material although in SA, there is an exception for waste fill. Or, Lightbody said, the fines could be approved as an alternative cover under approved specifications. Thus, discussions with the EPA began around the parameters required for the fines to be used as an alternative cover.

Testing the fines

Lightbody noted that in Australia, there were few common methods have been used to test the flammability, odour and methane emissions, and physical performance of trommel fines as an alternative landfill cover, though these tests certainly exist.

He turned to the ASTM D4982 “flammability potential screening – waste” to test the material’s flammability and a static method based on the ASTM D5975 to test respiration activity in order to determine the odour and methane emissions.

“For the physical performance of this material, there hadn’t been a lot of characterisation of particle size distribution (PSD) so we looked at that to see how closely the methods were replicated for the fuel,” Lightbody said.

Mockinya performed initial tests on a stockpile of material in 2013 over 10 consecutive days, followed by a five-day test in 2015.

The results

“The ASTM method for flammability tested whether the material would be ignited easily and sustain a flame. This testing was undertaken by an independent third party laboratory,” Lightbody said.

The result was that no, the material did not ignite easily nor did it sustain a flame. All samples were later classified as not potentially flammable.

However, there was a small amount of flammable material present in the fines, specifically:

  • plastic and paper, which would ignite and burn when contacted directly with the flame. It would then smoulder for up to 15 seconds; and
  • larger pieces of wood, paper and plastic that would ignite and burn when contacted directly with the flame and remain burning for up to 15 seconds.

Extinguishment followed after, Lightbody said.

Turning to the respiration activity, Lightbody relied on a modified version of the ASTM method developed by the laboratory that used proprietary and independent techniques around the containment of the gas within the chamber. Table 1 details the differences in the respiration activity tests; the middle column is the test that was undertaken.

WMAA landfill conference: exploring the use of trommel fines as landfill cover
Table 1: Testing respiration activity. (Source: Mockinya Consulting)

The test revealed that the rate of oxygen consumption had decreased over time with the highest four-day rate at less than 1mg of oxygen per gram.

“We were looking for variability in the factors that might affect the results but the results were consistent. We started to look at shorter timeframes because we were seeing a plateau in the respiration rates and we did, over time, develop confidence that we were seeing good and consistent data and we weren’t getting significant outliers in the data,” Lightbody said.

“One of the benchmarks we developed as we went through this program was based on Irish EPA guidance around the use of residual material for landfill cover application, which established the criteria of between four and 10mg O2/g and we were seeing results that were well inside what was thought to be a reasonable target. Thus, the conclusion was the organic matter was biologically stable.”

Finally, when it came to particle size distribution, Lightbody told delegates that this was “relatively consistent across the material” over the two testing periods. There was quite a good gradient of material and a reasonable amount of fines content – coarser content that provided the material some strength that would make it suitable to be used as a cover material.

“Other discussion points were the presence of glass and the perception that there is a fire risk due to the glass in the material,” Lightbody added.

“This is a myth in Australia that glass on the side of the road causes bush fires and our own fire authorities do teach their firefighters that it is a myth.

“The volatile solids are also within the range of carbonaceous soils, so that wasn’t a concern. We looked at all the impacts, even the stability of the material and it benchmarked reasonably well against the current soils that are used for cover.

“In summary, it forms a dense cover, it’s well graded, and it physically limits direct access for vermin – it’s not a food source for vermin. It is also not generating odour.”

The waste inclusions were also not significant to function as a cover though they are within approved specification limits.

In terms performance, Lightbody noted that the material has been used as an interim cover for three years now and in that time, it has remained stable despite some very heavy rainfalls.

“It has been accepted now by the EPA,” Lightbody said.

WMAA landfill conference: dealing with a leachate breakout

WMAA landfill conference: dealing with a leachate breakout

Speaking at the Waste Management Association of Australia’s 2017 Landfill and Transfer Stations conference last week, City of Darwin manager technical services Nadine Nilon told delegates the events that unfolded on January 17, 2014 have been etched on her memory forever.

On that fateful day, the council’s Shoal Bay Waste Management Facility noticed that leachate was leaking out of landfill cell four, marking the start of a six to 12-month process to clean-up, fix and review the situation. Read more

What is a solar energy landfill cover system?

What is a solar energy landfill cover system?

HDR’s innovative approach uses a highly durable geosynthetic cover equipped with laminate solar panels reducing cap construction, maintenance costs and providing a renewable source of power for a beneficial reuse of a closed landfill site.

Solar energy covers versus traditional systems

Traditional landfill caps include a geomembrane layer placed over a compacted soil base, a drainage layer (geocomposite/freely-draining sand), a protective soil cover, topsoil then grass to resist erosion and promote evapotranspiration (Figure 1). Failures of traditional caps often occur on sideslopes and are a result of slippage of closure components along an interface of dissimilar material.

A solar energy cover consists of an exposed geomembrane cover (EGC) upon which laminated solar panels are directly adhered.

An EGC provides a clean, stable, and relatively inexpensive closure system that reduces infiltration of precipitation into the waste mass and requires less maintenance with the benefit of being easily inspected to confirm its integrity and impermeability.

The EGC is attached to the landfill surface using anchor trenches to resist wind uplift forces. After installation, the EGC can be easily removed to access the waste or subsurface piping and reinstalled without the effort and expense of removing the soil cover and established vegetation.

Installation of an EGC can reduce the cost of closure by negating the requirement for vegetative support soil and top soil layers (useful when soil would otherwise be imported).

The effects of long-term exposure to the elements are well understood for many geomembrane materials, and these products can be used with confidence and warrantied against failure for periods up to 30 years.

What is a solar energy landfill cover system?
Figure 1: Solar energy cover vs. traditional landfill cover.

Laminate solar panels

Laminate panels can be adhered directly to a geomembrane on any area of the landfill where storm water does not pool. Their inherent flexibility is also more forgiving for undulated surfaces caused from surface grading or differential settlement due to waste decay/consolidation.

The efficiency of laminate panels has recently improved, and they can be spaced with higher density utilising a greater area as they can be placed on the crown and the sideslopes of landfills.

Maintenance and useful life

Panels will require cleaning, especially in arid climates, where dust from landfill operations tends to accumulate on the panels. Design life for laminate panels is approximately 20 years.

One manufacturer, First Solar, guarantees that their panels will produce 90% of the nominal power for 10 years, and 80% for 20 years (First Solar. 2009b).

Power generation

One of the most attractive features of a solar EGC is that it can be a source of revenue beyond the active life of the landfill.

Potential on-site uses include reducing the parasitic load of pumps, compressors and other equipment at landfill gas to energy facilities. The energy can also be used to power remediation systems and site operations or returned to the grid.

Case studies

HDR provided design, permitting and construction support services for the Hickory Ridge Landfill solar EGC (Atlanta, Georgia, USA). This project utilised an EGC design over 19.4ha with 4ha used for solar energy generation consisting of 7000 laminate panels to generate 1MW of renewable electricity.

The project provided benefits that include generating renewable energy, creating a revenue stream and eliminating erosion and dust. The laminate panels proved ideal because they are flexible, lightweight, require no bracing and thereby don’t add point load to the surface of the settling waste mass.

The laminated photovoltaic panels are approximately 6mm thick and generate electricity year round under high and low light conditions and temperatures. The system is designed so the panels can be easily replaced at the end of their useable life (with 20-year standard product guarantee to meet 90% of their rated capacity).

HDR has also completed a detailed concept study for a solar EGC at a landfill in Brisbane, Queensland. The study looked at applying a 2MW system to an area of approximately 4.5ha and the study indicated upside benefits of clean stormwater runoff and the ability to offset site generation needs whilst also feeding back into the grid.

Solar EGCs are increasingly being considered and successfully implemented at landfills throughout the world due to their significant benefits over a traditional cover.

The benefits that these covers offer landfill owners/operators include a more cost effective cover, improved stormwater runoff, and a renewable source of energy.

Judy DeVita, HDR principal civil engineer, is based in Brisbane while Kanishka Perera, HDR environmental engineer and Mark Roberts, HDR principal waste engineer, are based in Jacksonville, Florida. More: www.hdrinc.com.

This article was originally published in the February issue of Inside Waste.

Inside Waste (Feb): A tight race to the top

Inside Waste (Feb): A tight race to the top

Six years ago, Inside Waste launched the annual review and over that time, it’s been a process of constant refinement.

If you have followed the review since its inception (thank you for your support!), you’ll notice that this year, the survey was only sent to non-consultants, meaning consultancies big or small were not allowed to participate. Firms that slipped through the cracks were removed at the end of the survey. Read more

Waste Opportunist: The salt of the earth

Waste Opportunist: The salt of the earth

In January 2015, Queensland began exporting Coal Seam Gas (CSG, otherwise known as coal bed methane) to Asian markets. The volumes with these exports are expected to realise 1400BCF in 2017 alone, and combined with gas (including off-shore conventional gas) developments in Western Australia and the Northern Territories, are expected to ensure Australia’s elevation to be the world’s leading exporter of Liquefied Natural Gas (LNG) by 2020.  Read more

In conversation with Dale Gilson

In conversation with Dale Gilson

Inside Waste caught up with Gilson to find out more about the man behind the wheel.

IW: Tell us more about yourself… what were you doing before joining TSA?

Gilson: My working career began by spending 13 years in a third generation small business my family owned. It began as an IBM typewriter dealership (the kind you now see in antique shops) and progressed to sales and service of photocopiers, printers and facsimile machines. This is where I first learnt about customer service which was has been of great benefit to me as I moved in to the not-for-profit sector. Read more

Future-proofing Mackay's operations

Future-proofing Mackay’s operations

In December, Inside Waste spoke to Council about the seven-month evaluation period and procurement process two years in the making that would ensure best practices are implemented at the Hogan’s Pocket landfill and Paget Transfer station, including bulk waste haulage between the two locations (see Related Articles).

At the time, Inside Waste provided an overview of the procurement process as well as key aspects of the new contract arrangements. But these key aspects, specifically haulage and leachate management, are worth digging into. Read more