Water Quality and Drainage
	The existing junction is located high on the chalk plateau between the Thames and River Wye valleys and hence does not adversely impact on river flows or the flood plain. It is also outside any of the Environment Agency's Groundwater Protection Zones for the existing water abstraction points in Marlow, High Wycombe or Bourne End. The existing M40 Motorway and junction drains into a system of highway ditches and bored soakaways, which permit surface water runoff from the roadways to soak naturally into the chalk aquifer. This system of drainage will be retained for the drainage of the new pavement areas. In the event of an accidental spillage and pollutants getting into the drainage system, the Environment Agency requires pollution control devices to be provided upstream of the soakaways to protect and maintain water quality in the aquifer.

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