Landfill for Non-hazardous Waste in Ravenna (formerly Category I)

Compacting and re-covering of the waste with earth, stabilised organic fraction, fireproof and waterproof liner.

The leachate, or liquid waste, generated primarily by the infiltration of rainwater into the landfill site, is collected on a regular basis and then purified.
The drainage system, positioned above the waterproof tank liner, comprises a mineral drainage layer (gravel), a series of capture and collection pipes and an extraction system to carry the leachate in a pipe connected to all the sectors and which is transported to a system of storage tanks and reservoirs. It is subsequently channelled to the physicochemical treatment plant for purification treatment within the Section at 2.6 km S.S. 309.

The biogas produced from the landfill is taken from a horizontal and vertical extraction system consisting of drainage wells which, through a specific adduction network (HDPE piping), conveys it to the suction plants of each sector.

The biogas extracted from the 4°/5°/6°/7°/8°/9°/10° sectors is recovered energetically from a total of four cycle eight motors with installed electrical power of 836 kWe, 836 kWe, 625 kWe and, in the event of the shutdown of one or more plants, it is treated in high temperature flashlights.

The electrical energy produced is used to feed the utilities of the sector and the surplus fed into the external distribution network.

The biogas extracted from the older sectors (1°/2°/3°), not suitable for energy recovery, is sent to the experimental Biomether LIFE+ plant for the production of biomethane by upgrading from landfill biogas or, alternatively, to combustion in high temperature flashlights.

A secondary waterproof mineral barrier comprising clay, and a lower waterproof HDPE geomembrane that is 2.5 mm thick. A primary waterproof mineral barrier comprising clay, an upper waterproof HDPE geomembrane that is 2.5 mm thick, a protective layer of the liner comprising geotextile and fine sand, and a drainage gravel layer (bottom drainage of the leachate).

Covering of the top portion takes place in two separate phases:

• temporary covering (estimated duration 10 years): comprises a biogas drainage layer and Bentonite geocomposite having a sealing function;
• definitive covering: this chosen technique is primarily determined by the fact that, being a landfill for municipal solid waste and similar waste, the creation of a final covering soon after completion of the various landfill operation phases is deemed risky and inconvenient. Intervening with a temporary covering while most of the settling and subsidence takes place ensures more effective isolation of the landfill site from the external environment as restoration and maintenance interventions are easier to carry out than when a final covering is in place.

The final covering of the embankments will, on the other hand, take place in a single step. Given the objective difficulty involved in the onsite storage of large amounts of drainage materials with controlled characteristics (washed gravel or sand for the most part) and given the difficulty involved in placing the sealing material (clay) on the embankments, evaluation of a final covering system using synthetic material is underway. This decision allows certain guarantees on the effective disposal capacity (water and biogas drainage) and on the sealing capacity with a significant reduction in the weight of the covering that benefits the stability of the landfill system.

The environmental matrices and emissions monitored as environmental surveillance of the potential impact of the operational management of the landfill are:

• rainwater;
• groundwater;
• surface water (receiving vessels);
• leachate;
• atmospheric particulate;
• monitoring of biogas composition;
• landfill emissions;
• air quality (Odorous substances);
• monitoring of leachate explosiveness on the management network;
• noise monitoring.