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The Leachate Expert Website

Leachate Landfills

leachate landfills - view with landfill gas extarctionWe have noticed that many people search the internet using the keyword phrase “leachate landfills”.

To satisfy their request we have written this post in which we have tried to answer their search by providing general information about leachate, and how it is present in landfilled waste, affects landfills, and is collected.

Leachate landfills are all landfills in areas which are not so arid as to not produce any net free liquid which becomes leachate. Very few landfills never produce leachate. Even landfills in arid areas produce leachate in wet weather conditions, although such events may be few and far between.

Leachate landfills will also continue to produce leachate for many years after they are capped, restored and closed for the acceptance of waste. In fact most landfills will be monitored for at least 30 to 40 years after closure, to ensure that no leachate (or landfill gas) escape into the environment and present a risk to the communities surrounding the landfill site.

In older landfills and those with no membrane between the waste and the underlying geology, leachate is free to egress from the waste directly into the groundwater. In such cases traces of leachate will be often found in nearby springs and streams or rivers.

As leachate first emerges it is often black in colour, anoxic and may be effervescent with dissolved and entrained gases, for a short time after it leaves the landfill. Over some hours of exposure to the air, it becomes oxygenated and it tends to turn more cloudy and brown, or yellow, because of the presence of Iron salts in solution and in suspension

Most landfills containing organic material will produce  methane , some of which dissolves in the leachate. This could in theory be released in confined spaces in the treatment plant, or sewers. All plants in Europe must now be assessed under the EU ATEX Directive and “explosion risk zoned”  where explosion risks are identified by doing a risk assessment. This is to prevent future accidents. However, the most important requirement is the prevention of the discharge of dissolved methane from untreated leachate, when it is discharged into public sewers. Most wastewater treatment authorities limit the permissible discharge concentration of dissolved methane to 0.14 mg/l, or 1/10th of the lower explosive limit. This usually require methane stripping from the leachate.

More modern landfills in the industrialized nations (often called sanitary landfills) have some form of low permeability liner (membrane) separating the waste from the surrounding ground to reduce leakage of leachate into the geology to very low levels. In such sites leachate must be collected.

A leachate collection system is provided comprising a series of pipes laid on the lining in the base of the site, to convey the leachate to a storage or treatment location .

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11 Responses to Leachate Landfills

  1. cavro May 15, 2012 at 6:30 pm #

    je prepare un examen(attestation de capacite)attant chauffeur routier et transportant du lixiviats j’ai desidé pour mom memoire de prendre comme sujet le recyclage des dechets et leurs utilités pour les energies renouvelable je suis donc a la recherche de documentation si vous pouviez m’en transmettre,je vous remercie christine.

    • leachater June 22, 2012 at 11:09 pm #

      Cavro – I translated your comment as follows: “I prepared a review (proof of capability) about road drivers and carrying of leachate. I desire to carry out the recycling of waste and their utilities for renewable energies. I’m looking for research documentation if you could send it to me, thank you. Christine.”

      You can transport leachate and treat it, but I do not know anyone who is using leachate from established landfills to create renewable energy. If you succeed in doing that you will be very doing very well. I do not have any research on making renewable energy from leachate. I do not know anyone that is doing that.

  2. Dee May 16, 2012 at 3:21 pm #

    What sort of environmental impact are these leachates having? Are they causing water pollution? Air pollution? Are they affecting the ozone layer?

    • leachater June 22, 2012 at 11:14 pm #

      At some landfills (where leachate is not controlled) I am sure that leachate is getting into the ground and from there into wells and boreholes and therefore also into water supplies.

      Leachate can cause a lot of odour if it is left out in lagoons untreated.

      Air pollution? No, not significantly, other than odor as mentioned earlier.

      Leachate will not be affecting the ozone layer in my opinion.

  3. Kim Hawkes August 29, 2012 at 5:32 pm #

    I understand that methane gas is generated by the decomposition of organic material in an oxygen poor environment. I have a question. If a leachate plume is migrating away from the waste. Is there a significant potential for methane to off gas into the unsaturated zone from the plume (as opposed to the landfill ?)
    Has anyone studied that ?

    • leachater August 29, 2012 at 9:00 pm #

      I don’t know of any studies but they may have been done. It would need a lot of leachate to produce much gas around in water-bearing strata around the landfill. Wouldn’t those need to be pretty unusual geological circumstances?

  4. Kim Hawkes August 29, 2012 at 5:34 pm #

    does a leachate plume off gas methane gas in significant quantities once it leaves the waste fill area ?

    • leachater August 29, 2012 at 8:57 pm #

      I have not known of a case specifically, and in most cases if it were to produce much gas, the leachate would be getting out of the landfill so the much larger volume of LFG I would expect usually also to be present migrating from within the landfill would be a bigger source and mask any methane produced in any anaerobic zones in the ground around the landfill.

  5. Richard Smith June 28, 2013 at 1:59 am #

    here in Victoria, Australia, a company named th R.E Ross Trust want to turn a dissused quarry into a putrecible and asbestos single cell 300 million tonne landfill. there are many concerns such as the fact it is in the middle of a state park, with extremely high bush fire risks.
    Concerning leachates, the quarry sits on a steep hillside, submerged 25m into the water table and recieves over 800mm per annum of rain. There has been many records of summer storms delivering in excces of 100mm at a time. there are 3 streams running into the site and a creek which flows out to the sea, approximately 3km downstream from the tip.
    In your experience have you come accross a proposal of this nature and could you tell me where?
    If you need more details, please see http://www.Save arthursseat.com
    Regards
    Richard

    • leachater November 26, 2017 at 4:06 pm #

      Richard Smith Unfortunately, I do not have any comparable proposals. That really is an enormous landfill.

  6. Alvin Horton November 13, 2017 at 9:52 am #

    I have seen a new area near our local landfill which has become boggy and a really rusty water is running out of the ground. Would that be leachate? How would I find out? Please answer.

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