Anaerobic Digestion Plant

Britcon were engaged as principal contractor to construct a state of the art anaerobic digestion facility capable of converting in excess of 45,000 tonnes of food waste into power generating methane gas to be used as a fuel source for the adjacent feed processing factory with excess power being fed back into the local electricity grid network, producing overall 2.8Mw of renewable electricity and heat, enough to power about 5,000 homes.

The anaerobic digestor takes 25-36 days to complete its cycle. As well as heat and electricity, it produces 43,000 tonnes of odourless organic fertiliser a year, which is sent to local farms.

Our client was Prosper de Mulder Ltd. in partnership with their European anaerobic digestion plant operators SARIA who have a number of similar installations on the continent.

PDM were keen to use local supply chains and as such invited local companies to tender for the project. Britcon were selected as principal contractor. On appointment, Britcon engaged in an intense process of value engineering to ensure 'best value' had been achieved throughout the entire project providing civil engineering infrastructure and construction of a new dedicated office and amenities block for the AD plant, which is highly energy efficient, in line with the rest of the project.

The initial phase was a relatively straight forward earthworks re-engineering of the top 2m of the existing brown field site to bring the formation to a suitable bearing capacity for the structures to be constructed but this did incorporate a major dewatering of the temporary works for the deep basement which was a considerable depth below the adjacent river level.

On completion of the earthworks and piling operations, the major structures which comprised multiple high rise post tensioned circular reinforced concrete digestion tanks, receiving tanks and gas storage tanks along with numerous process structures, extensive external works and administration office commenced.

The concrete tank structures were sub-contracted to a nominated Austrian specialist slip forming contractor utilising their own patented shutter / integrated rotating equipment.

Given that the administration office was to be used in conjunction with a green energy plant, the brief was to create an office facility that was as environmentally friendly as possible, using the latest sustainable methods of construction. With this in mind the materials were sourced to provide maximum recycleability over the whole life cycle of the building.

Thermal values of all elements of construction were closely considered, with the eventual building envelope far exceeding the requirements of the Building Regulations. Internal walls and the inner leaf of the external walls were formed with dense masonry to provide high thermal mass; to be used in conjunction with a night-time cooling strategy, fresh air is brought into the building overnight to cool the dense structure which slowly absorbs heat through the day. In winter the air is not extracted and thus stays warm.

Architects, John Hill Associates from Doncaster, managed the design and construction throughout the build process.