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.

Progress to 100% renewable energy in Victoria

Progress to 100% renewable energy in Victoria

These are ambitious targets and the following questions need to be asked:

  1. Are these targets being aimed for elsewhere?
  2. If so, what progress are these other countries making toward achieving these targets?
  3. In those countries what are the distinctive developments that are allowing such progress to be made?
  4. Does Victoria have similar policies, programs and progress to allow these goals to be met?
  5. What real actions are needed in Victoria to improve the chances of meeting these targets and goals?

Read more

Future Focus: Getting from a linear to a circular economy

Future Focus: Getting from a linear to a circular economy

We need to make changes to both, particularly the recycling system, at both the macro and micro level, if we are to grow into a more resilient and sustainable circular economy.

In a circular economy, already used materials and products are renewed, reprocessed and integrated back into the economy for overall greater productivity.

According to the National Waste Report 2013, for the period between 2010-11, around 40% of what we produced and used in Australia went to landfill or incineration. Read more

The state of the waste data

The state of the waste data

The SOE concludes that: “Despite an overall increase in waste generation, Australia’s total disposal tonnage decreased from about 21.5 megatonnes to about 19.5 megatonnes (about 9.5%) between 2006-07 and 2010-11. During this period, the resource recovery rate in Australia increased from 51% to 60%. The quantity of material recycled increased significantly from 21.4 megatonnes to 27.3 megatonnes per year, or by about 27%.” (Australian State of the Environment 2016, p.90) Read more

Sydney Markets' environmental upgrade continues with new solar array

Sydney Markets’ environmental upgrade continues with new solar array

The 640kW structure will save 936 tonnes of carbon each year – the equivalent of taking 522 small cars off the road annually – and was built as part of Sydney Markets continued commitment to environmental sustainability.

The extension will provide an additional 350 parking spaces in the multi-level car park, as well as a new 4.5 tonne goods lift.  Read more

Building a clear vision for waste and resource recovery infrastructure

Building a clear vision for waste and resource recovery infrastructure

One issue that should be high on the public and government agenda, which requires further debate and discussion is who really is responsible for the provision and planning for waste and resource recovery infrastructure in Australia?

Increasingly, we hear “let’s leave it to the market”. Is this, however, really the right approach, given the importance of waste and resource recovery facilities for both public health and amenity, as well as the need for these facilities to support the urban growth predicted by governments in almost all Australian states? As we all know, if there is ever an industry that encounters NIMBYism, it is this industry. So, is it really appropriate for government to simply “leave it to the market”? Read more

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

Green Box Thinking: Outcomes from the APC think tank

Green Box Thinking: Outcomes from the APC think tank

Say the word green to most people and they think of trees, the environment, the earth, and sustainability.

However, before you reach for a tree to hug, we need to challenge this belief.

Dr Leyla Acaroglu (2016 UNEP Environment Champion of the Earth), speaking at the Australian Packaging Covenant’s (APC) inaugural Packaging Sustainability Think Tank last month, reinforced the true meaning of sustainability. Read more