Planning Permission: What’s beneath the surface?

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With easy access to modern materials, skilled labour and a need for affordable housing, getting the green light for building developments in London should be easy RIGHT?

Well in some cases not everything is as it appears on the surface and getting planning permission can go seriously WRONG! You can grow and give birth to a baby in 9 months but that’s how long it took us to obtain a piece of paper giving us permission to start work on a new build in Dulwich, south London.  The cause of this delay?

The Great Stink during the summer of 1859 and a guy called Joseph Bazalgette.

The Great Stink occurred in central London in July and August during which the hot weather worsened the smell of human waste and pollution that was present on the banks of the river Thames. The awful smell, outbreaks of cholera and fear for public health finally prompted the local government to address the ageing and inadequate sewer system that emptied directly into the Thames. Joseph Bazalgette designed and implemented an interceptor sewage system which would relieve London of its sewage problem forever.  Construction of the interceptor system required 318 million bricks, 2.7 million cubic metres of excavated earth and 670,000 cubic metres of concrete.  The innovative use of Portland cement strengthened the tunnels, which were in good order 150 years later. His sewer system still operates today, servicing a city that has grown to a population of over eight million. But by solving the sewage problem all those years ago it’s these Victorian sewers which are causing problems for developers in the 21st century.

At first glance the plot of land in Dulwich looked like the perfect place to build four brand new 2 bed apartments, but the discovery of the Victorian sewer running directly beneath the site was a major concern. Finally, after 9 months of negotiations, surveys and a lot of nail biting we managed to obtain a build over agreement from Thames water.

Due to the sewer running beneath the ground and the weak soil above it we will have to use piling for our foundations instead of the more conventional and cost effective trench foundations.  Trench fill foundations are a type of shallow foundation that avoids bricklaying below the ground by instead almost completely filling the trench excavation with concrete.  This type of foundation minimises the excavation required, as bricklayers are not required to access the trench to lay bricks or blocks. Pile foundations are deep foundations formed by long slender columnar elements typically made from steel or reinforced concrete. They transfer the heavy loads of structures, through weak compressible layers onto stronger more compact and stiffer soil at depth, increasing the effective size of a foundation and resisting loads.  In other words Thames Water wanted the building above their Victorian sewer to be built in the sturdiest and secure foundations possible.  Sewers play a vital part in keeping London’s water clean; they are the underground arteries that pump waste away to keep us alive and healthy.  So it’s understandable that Thames water want to ensure they aren’t damaged and they can still be accessed for maintenance.

Like a heavily pregnant woman the planning for this project required a lot of care, attention and patience but with the piling due to start at the end of October the building will be in its infancy. 36 weeks later with planning permission in place this building ‘baby’ can be officially born and the team at Balma Building services can’t wait to watch it grow.

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