If the preliminary examination is thorough, 97.5 percent of a demolished school can be recycled. The symbiotic way of thinking has ensured that the demolition of the Baunehøj school in Holbæk is 160.000 DKK under budget.
The baunehøj school in Holbæk was old and run down. The school was far from being up to date and the building from 1971 was in bad shape.
The municipality made the only correct choice, demolishing the school. But demolitions are expensive – and what if the building material turns out to be toxic?
In order to head off any unpleasant surprises, the municipality decided to spend both time and money on a thorough preliminary examination of building materials as well as the soil in the area. The preliminary examination was conducted by a cross-functional team from consulting engineering company NIRAS.
Unforeseen events were taken into account in the demolition budget of 4.7 mil. DKK. The extra budget money were, however, not needed because of the cross-disciplinary approach to the project. The total cost of the demolition was nearly 4.5 mil. DKK.
‘The thorough preliminary examination ensured that very few surprises arose during the actual demolition, and the ones that did were hidden from the examiners.’ Says Søren Kofod; project manager from the public works department under growth and sustainability from Holbæk municipality.
All about symbiotic thinking
The public works and environmental department in Holbæk municipality has worked closely together with NIRAS and demolition contractor Søndergaard Demolition A/S.
Prior to the demolition a resource inspection of the building was performed, in which materials suitable for recycling were identified. Three different departments from NIRAS were involved in the resource inspection, the environmental department, demolitions, and the symbiotic group, in order to ensure that everything was considered.
All information, regarding environmentally dangerous chemicals in the soil as well as in building materials from the school, was thoroughly examined prior to the demolition being tendered. This lead to the majority of materials from the old school being recycled.
‘Often the tender documents for demolitions are made before a plan for disposing of building materials is in place. In this instance it was done the other way around, which meant that it was possible to consider the symbiotic effect to a much higher degree, thereby creating value,’ says Solvejg Qvist, Master of Science in Engineering and project manager at NIRAS
Pure materials for recycling
After the environmental clean-up of the buildings, all the pure material such as, concrete, iron, glass, and roofing felt were recycled. It was ensured that the materials were pure by thoroughly mapping which materials contained toxic substances. The materials containing toxic substances were then sanitized before being sold for recycling.
The preliminary examination showed oil contamination in the ground around a sunken oil tank as well as soil containing contaminated debris in an old swimming pool, which everyone was surprised existed under a wood building. After cleaning the soil and the old swimming pool, there was a deficit of 1.000 m3 clean soil. However, this was solved by reusing soil from a road construction in Søbæk Have, Jyderup.
In return, the 2.000 tons of pure crushed concrete from the Baunehøj school was transported to Søbæk Have, where it was used as sub base gravel under the new road.
The recycling percentage for all of the demolition ended up being 97.5. The 2.5 percent left was taken to a landfill
‘It is all about considering the big picture in these projects. In this project local resource were optimally used, because everything was taken into consideration early in the process, not just the demolition. The municipality, the contractor, and NIRAS worked closely together on the project, ensuring the excellent result,’ says Solvejg Qvist.
The now empty and clean plot of land of almost two hectares is ready to be tendered, as decided by a majority of the Holbæk municipality city council.
At an open meeting in January, the city council asked the citizens for suggestions on what the plot can be used for.