Barr Environmental Explains the Background to the Garlaff Leachate Treatment Plant Project

The following is based upon an article about the latest Enviros designed and commissioned Leachate Treatment Plant, published in the July 2009 Edition of the Community Newsletter published by Barr:

Rain falling on the waste in a landfill is held within the plastic lining the waste sits on, which is intended to stop the rainfall entering the soil and rock beneath.

As site operator Barr Environmental needs to pump it out of the waste and treat it as per their SEPA waste permit. Till last year the leachate from the waste at Garlaff was treated in an open lagoon system close to the site entrance. While this plant still worked it was built many years back and wasn't able to treat the leachate to the highest standards now feasible. This old plant has been substituted by a state of the art treatment system beside Cell two of the rubbish heap.

The new plant is one of the most recent systems in the United Kingdom and was designed by leading leachate professionals Enviros. The consultants have designed over one hundred plants around the globe to treat this kind of waste water and have advised the UK govt and in particular the DEFRA government department in the Best Available Techniques (BAT) available for this kind of leachate treatment.

The plant is entirely automated and computer controlled and can nicely treat all of the leachate the landfill site produces every day. The system was built by Barr Surfacing & Civil Engineering and largely invisible from outside of the site as four fifth's of the plant is built below ground, rather like a below ground multi-storey car park.

The leachate is pumped from the rubbish heap from a series of wells in the waste to an large holding tank in the plant. There were some concerns about odour from this tank. So, all the tanks have been sealed at the top to stop any smells entering the air round the site before the leachate starts to be dealt with.

The main treatment tank is aerated and the leachate treated using the natural microbes in the sludge in the tank in the same way a sewage plant works. These microbes are specifically evolved to treat the ammonium rich liquid to provide a clean liquid that is fit for discharge to the brook.

The plant has been engineered to the most recent standards with a high efficiency energy rating that's achieved by insulating the tank with earth around it and transferring the heat from the aerators into the treatment liquid. Keeping up the leachate temperature through the winter at about 25 degrees C creates the ideal conditions for fast decrease in the pollutants within the aeration tank.

Still working with nature the final part of the treatment process uses natural reedbeds on site to shine and take away the last traces of solids and nitrogen.

The reedbeds have proven to be a helpful habitat as well to wildlife. They will quickly become home to many insects and the tiny birds that eat them.

Barr have been so happy with this new leachate plant that they have just built its twin at their other landfill site, at Auchencarroch in West Dunbartonshire, Scotland. Together these plants are the biggest and most modern leachate plants to ever be built in Scotland and controlled by one company.

The plants will operate for no less than the next 30-40 years till the leachate has been fully treated on the site and no longer is required to be removed.

Environment Agency UK Issues Guidance on Environmental Permitting for "Orphan" Leachate Treatment Plants

Earlier this month (July 2009) the EA's Modernising Waste Regulation Panel issued a Regulatory Position Statement about Environmental Permits for Waste Treatment Plants.

This has updated a previous pair of statements on this subject which we found hard to interpret, and which were issued a least a year ago.

Under the original EU Directive based PPC Regs. and UK permitting rules it appeared that in due course all leachate treatment plants greater than 50 tonnes per day (50 cubic metres per day) capacity would have to be officially issued with a permit by the Agency. This would be the case even if the plant had been in existence for many years and was clearly complying with its watercourse (or sewer) discharge consent and not causing any environmental problems at all.

From the start this seemed absurd, and an enormous cost and bureaucratic burden on the operators of these plants, without anyone really being clear what benefit would result.

As time progressed and the Environment Agency concentrated on prioritising the most important treatment processes and all new landfills, we all wondered when they would catch up with this and start contacting the operators of these so called "orphan" sites.

Now, finally it seems that most if not all leachate treatment plant owners and operators that do not already have an Environmental Permit, or have been required to submit for one, for their leachate treatment plant can relax about this.

The position statement says:

The Environment Agency’s position:

We will not pursue an environmental permit application for an IPPC directive waste treatment activity where all the following conditions are met:

• the treatment plant is subject to a consent issued under the Water Industry Act or the Water Resources Act;

• the plant only treats waste/waste water produced on-site and does not import it from other sites;

• management of the activity ensures that the risk of pollution incidents from the site, including nuisance, remains low;

• relevant operational records are kept for a period of four years and made available to Environment Agency officers when requested.

However, if you do own or operate a leachate treatment plant on what would usually be a closed landfill, you should not rely on this posting alone, and you really should visit the EA's web site and read it for yourself at the WTP Orphan page/pdf.

However, here is a thought to end this post. How many closed landfill leachate treatment plant operators have a full 4 years of data properly archived and ready for inspection, if requested. I wonder!?