Contaminated Soils & Waste

Specialist treatment services for the rehabilitation of contaminated soils and waste.

McMahon Services use a variety of methods to treat contaminated soils and solid waste. Our bioremediation techniques include bio piling, land farming and co-composting. Our chemical stabilisation solutions include fixation, immobilisation, microencapsulation and solidification. Our chemical oxidation / reduction techniques include both in-situ and ex-situ techniques.

Treatment Methods

The following techniques have been implemented by McMahon Services on a variety of projects bringing tangible remediation outcomes for clients and their infrastructure assets and land:

  • Bio piling involves heaping contaminated soils into piles or cells, then stimulating aerobic microbial activity to perform decomposition by natural biological processes, aided with soil aeration, irrigation and nutrient systems.
  • Land farming is where the soil is laid out into relatively thin layers, and periodically turned over to aerate the mixture, thereby cultivating microbial degradation of hazardous compounds.
  • Co-compositing is the process of mixing contaminated soils with a compost feedstock, such as sludge with high moisture and nitrogen content and biodegradable solid waste high in organic carbon molecules, that when mixed optimise the aerobic degradation process of both wastes.

Treatment Methods

  • Chemical stabilisation techniques limit the solubility or mobility of contaminants, achieved by introducing reagents or other specialised materials which are blended with the soil. Stabilisation ensures that the hazardous constituents are suspended in their least mobile or toxic form.
  • Fixation and immobilisation is similar to chemical stabilisation, with the added benefit that the blending process creates a chemical reaction that bonds the reagent with the contaminant to create non-hazardous materials.
  • Solidification or microencapsulation creates a solid, low-permeable block of contaminated soil. This is created with reagents that mechanically lock the contaminants within a solidified matrix, signification reducing the likelihood of contaminant migration as well as reducing the leachability of the waste.
  • Chemical oxidation/reduction techniques are widely used to treat contaminated soils or groundwater, and can be applied both in-situ and ex-situ. In-situ techniques involve injecting or directly mixing reactive chemical oxidants/reductants into groundwater or soil for rapid and complete contaminant destruction. This technique can remediate a variety of organic compounds including some that are resistant to natural degradation. Ex-situ chemical oxidation is the same process but conducted in a vessel or stockpile, allowing sufficient time for the reaction to occur in a controlled environment.

Specialist Solutions

McMahon Services fleet of in-house owned and operated fleet includes specialised plant and equipment capable of rehabilitating contaminated soils and waste.

With over 400 major plant items, we are able to tackle bulk earthwork soil remediation projects in New Zealand.

Our Komatsu Reterra G-mode specialist soil recycler provides fast and accurate blending of soils to neutralise and stabilise contaminated soils, at rates of up to 150m³ per hour.

Specialist Solutions

Contaminated soils and reagents are mixed in a chamber consisting of a soil cutter and three flailing hammers, then discharged via another soil cutter. This ensures an effective mixing between reagents and contaminated soils. The process is controlled with an inbuilt computer system, which monitors the throughput of reagents and soil to ensure volumes of material processed are accurately known.

On several client sites, we have installed and operated Lo-CalTM high temperature flares for the safe and control of gas drain from old landfill sites.

Our fleet includes a PistenBully 600 snow plough modified to remediate and cover low density contaminated ground materials where traditional plant and equipment would sink or become bogged.

Do you require tailored soil or waste treatment services on your project? Contact the expert team at McMahon Services to assist you with safe, cost-effective and innovative solutions.

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