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Clearing the Site

Designers Knowledge Base

This includes demolition, below ground structures and services, the removal of waste and earth, tree felling and water removal.


In considering site clearance issues the designer should be aware of, and assess the risks from, the following principal hazards.

Some principal hazards and risks

  • Health hazards caused by toxic waste, gas from decomposing materials, asbestos and microbiological agents
  • Noise, vibration and dust during breaking up of structures
  • Falling from height: into excavations, from existing structures because of inadequate access or poor working platform
  • Hazards from services such as electricity overhead or underground, underground services etc.
  • collapse of excavations due to underground voids, buried obstructions, poor ground conditions or the water table
  • flooding ,fire, or explosion, caused by underground or above ground services
  • Confined spaces in buried structures, sewers, manholes etc.


When looking at the site consideration should be given to the previous uses of the site and the need for a site survey to identify any hazardous or toxic materials such as asbestos. Consider that the site may be unstable, it may be necessary to identify any existing structures or services below and above ground. The need for any demolition must be carefully considered in terms of the methods to be used and the control of hazards such as dust which are inherent in such activities.

Some possible design options

  • consider building in areas remote from existing services
  • seal contaminated ground rather than remove and replace options
  • design service diversions to avoid site clearance
  • use site demolition material as hard core fill
  • consider driven pile foundations through contaminated ground to minimise open excavations
  • site new foundations to avoid existing obstructions