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Gaggio Montano landfill for non-hazardous waste

Loc. C dei Ladri, 253 - 40041 Gaggio Montano (BO)

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The Gaggio Montano sanitary landfill for municipal waste and non-hazardous special waste, in operation since 1985, is located upstream of the SS 64 Porrettana road in the section between Marano and Silla, two hamlets in the municipality of Gaggio Montano in the province of Bologna.

Built on a hillside, it covers approximately 25 hectares.

The plant is configured as a "sloped" landfill located within a ravine consisting of clay rocks and has been divided into sectors to streamline its management and ensure maximum safety in terms of stability and to minimise risks to the environment.

Each sector is stand-alone and autonomous from an engineering point, both structurally and operationally.

The plant is included in the Structural Plan of the Municipality of Gaggio Montano as an Infrastructure of general interest as a "Plant for the environment and related services".

Page updated on 26th July 2019

    Landfill type
    non-hazardous waste and non-hazardous mixed waste with a high level of both biodegradable organic waste and inorganic waste, with biogas recovery
    since 1985
    Expected saturation
    General characteristics of the landfill
    Area filled with deposits: approx. 23 hectares.
    Authorised residual volume
    Approx 95,100 m3 overall
    Overall usable capacity
    V Sector 366,048 metric tons

    Waste accepted for storage in the landfill must follow and comply with the requirements of the Operational Management Plan approved by the Competent Authorities.
    Non-separated municipal waste is crushed and screened to adapt the pretreatment of the waste to applicable regulations.
    The screening, following crushing, separates the predominantly organic part of the waste which is sent to external biostabilisation plants.
    The remaining waste (lightweight materials) is stored in the landfill.
    Special waste is placed directly in the tank without crushing, spreading it with a wheel loader and then compacted by rolling with a waste compactor, with hammer wheels.
    The open face is covered every day using a layer of protective material of suitable thickness and specification, to reduce wind dispersion, access to birds, odour emission and the proliferation of insects, rodents, and larvae.

    The leachate produced by each sector of the landfill is collected in separate groups of sealed underground concrete tanks and periodically delivered by tanker truck as waste to plants authorised for its treatment.
    Since the landfill is on a slope, the leachate is collected almost exclusively through gravity.
    For improved safety of the plant, the system of independent tanks also has an "overflow" connection to adjacent tanks and a remote control system to continuously monitor the level in the tanks.
    An experimental leachate management system has also been adopted to reduce it and make it easier to recover.
    The process consists in dispersing the leachate using subsurface irrigation in tanks which have already been closed for some time.
    This system reduces the waste mineralization time, improving the production of biogas through increased humidification of the stored waste.

    The biogas that is produced by the landfill is taken from a vertical collection system consisting of drainage wells which, through a specific surface supply network (HDPE pipes), conveys it first to the control substation and then to the intake plant.
    The extracted biogas is purified by cooling and draining the condensate and passing it through active carbon filters. It then fuels an electricity generator the engine of which equipped with a regenerative afterburner to control emissions.
    When the generator is not working due to a fault or maintenance, the biogas produced is thermally destroyed in a torch.
    The torch is always active (in stand-by) and starts automatically whenever a malfunction causes the engine-generator to stop.

    The supporting substrate of the tanks is made up of the clayey chaotic complex, which is a formation made up of layers of clay several hundred meters thick.
    This substrate is a natural protective element of the subsoil.
    The bottom of each tank is sealed with an impermeable lining of bentonite geocomposite.
    The first step of the waterproofing process involves preparing and compacting the tank bottom, laying the waterproof package, positioning of the secondary leachate ducts and the drainage package consisting of a layer of at least 50 cm of inert material.
    A layer of non-woven fabric is laid across the entire bottom before laying the drainage package.

    The final setup includes a multi-layered cover made up of the following (from the top down):

    • sand, crushed sand and stabilised organic fraction (FOS) levelling layer
    • biogas drainage and capillary breakage layer protected from clogging using a suitable layer of gravel or draining geocomposite, with hydraulic transmissivity equivalent to a 50 cm thick layer of gravel
    • a layer of compacted clay with a permeability coefficient not exceeding 10-8 m/sec, and at least 50 cm thick.

    After settling, the following layers are added:

    • a drainage layer to prevent the formation of a hydraulic head and consisting of a bi-planar drainage geocomposite
    • a cover layer of with topsoil, possibly mixed with soil improver in compliance with Italian Legislative Decree 75/2010 on fertilizers, with a minimum thickness of 50 cm.

    To enable the natural recovery of the site, an Environmental Recovery Plan is envisaged which spans a long period since the greening operations must be preceded by reshaping the tanks and arranging the hydraulic network.
    The latter is divided into two stages: the first is carried out 1-2 years after the tanks are closed; between the first and second stage, a period of time is required to allow the drifts to settle of and assume a morphological configuration that is more stable a similar to the final shape.
    In the second stage, the more specific vegetation recovery operations are carried out with greening activities involving spreading quality compost mixed with soil and enhanced hydro-seeding with a mixture containing grasses and seeds of species typical of the local territory. Lastly, native trees are planted along the main water lines of the surface hydrographic network.

    The environmental media and the emissions that are monitored as part of the environmental surveillance on the potential impacts of the landfill are:

    • surface water
    • leachate
    • leachate recirculation system
    • emissions delivered to co-generator
    • biogas quality
    • emissions from the landfill matter
    • air quality
    • noise
    • traffic
    • water extractions
    • raw materials
    • combustibles
    • energy production and consumption
    • morphology of the landfill
    • weather and climatic parameters
    • inbound waste
    • outbound waste
    • recovered waste
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