Centrale Gelderland Power plant – Explosive Demolition

Brown and Mason Group (BMG) were contracted by the multinational energy company Engie to undertake the decontamination, dismantling and demolition of their Gelderland power plant in The Netherlands. The contract was awarded on BMG’s unappareled experience and involved substantial asbestos removal and extensive use of explosives, all within the timeframe of Brexit, Covid and the war in Ukraine

Centrale Gelderland, a 585MW coal/biomass-fired power plant, including structures 150 Meter high chimney and 95 Meter high boiler house , located in the city of Nijmegen was the first in The Netherlands with a flue gas desulphurisation installation that provided a reduction in sulphur emissions of up to 90%, with the LowNOx burner reducing the formation of nitrogen oxides by 50%. The 1994 constructed DeNox further reduced nitrogen oxides with the use of a catalyst. Large dust collectors and electrostatic filters removed around 99.9% of fly ash particles from the flue gases before they left the plant through the chimney. Engie’s facility had been at the mouth of the Maas-Waal Canal since 1936.

The power plant was constructed on the bank of the river Waal bordering the Maas-Waal Kanaal to the North, to the East and to the South of the site the power plant was boarded by heavily mixed industrial and residential estates. The site contains photovoltaic parks and an electrical substation which form part of the national infrastructure powering the City of Nijmegen, and located to the site’s western boundary is the district of Weurt, a very sensitive and affluent residential area, a political ‘hot potato’ with the historical operations of Centrale Gelderland Power Plant and other industrial operations.
The initial explosive events for the Precipitators and Chimney were very successful, however, as previously noted, The Netherlands have not quite experienced anything like this before. Media exposure was huge, and the realisation of explosive demolition and the site’s sensitive location saw the governing bodies (ODRN, NLA, etc.) introduce greater environmental controls, which saw their internal processes and procedures adapted to accommodate this type of work. What was introduced wasfar from what has typically been experienced in other European countries and the UK, these were not easily achievable, borderline impossible, and as a result, a Blowdown Committee was introduced into the contract as a variation. The Blowdown Committee comprised the client (Engie), BMG, ODRN, the Police, Waterschap Rivierenland (Dyke Authority), and Rijkswaterstaat (Harbour Master). BMG agreed to a contract addendum, BMGs apportion of risk became greater, the disparate stakeholder involvement, additional environmental controls, extensive bureaucratic constraints, and communication management to navigate and gain approvals from the various parties, each with their own governance and agendas, caused greater complications. The onerous process and protracted approvals began to affect the programme. It was no longer possible to complete the works as planned, it was decided to combine the explosive demolition of all five main structural elements into one event.

The DeNOx structure collapsed in a westerly direction to allow space for the BH to collapse, LSCCs were used to decouple the structure from the boiler support. The northern support columns were explosively removed, and the bridge section was displaced at a high level, a design solution that reduced the number of explosives with consideration to the heavily mixed industrial and residential estates sited c.165 m south of the structure.

Pre-weakening and use of LSCC, along with the explosive displacement of both main and façade support columns at ground level, allowed the BH to collapse into the space created by the collapse of the DeNOx. The Air-Heater support structure was the final element to collapse due to the concrete construction and not wanting this to interact with the other charged elements. To prevent this structure’s initiation from being disrupted, down-hole delay detonators were used in charging and initiated in advance of the surrounding steel structures.

In addition to the project constraints, the war in Ukraine provided challenges, we could not source the preferred selection of delay detonators and connectors, which led to an already hugely complex design and explosive delay sequence becoming even more complex to ensure we retained the desired timings and collapse mechanisms, class one shipping was cancelled on numerous occasions with priority being given to Ukraine resulting in the LSCC only arriving in Europe with days to spare.

The timing and placement of the kicking charges and LSCC were designed to avoid sympathetic detonation/interference where cut-offs would prevent initiation. The design ensured that peak vibration predictions would not affect the Dyke and the stakeholders.

The project was a huge success, this was the largest and most complex explosive demolition event of a structure in The Netherlands, and a feat undertaken by a British Contractor.