Avonmouth House, London

Private Drainage and External Hardstanding Detailed Designs

Services offered

  • Private Drainage Detailed Design
  • External Hardstanding Detailed Design

The brief

Civilistix Consulting Engineers were appointed to prepare a Private Drainage Strategy and External Hardstanding Design for a development for tender, building regulation approval and so construction could commence. The development consisted of a 14 storey plus 2no. storey basement, creating 233 residential units.

What we did

Due to the site being located on underlying London clay and the risk of mobilising pollutants in made ground, the use of drainage infiltration systems was deemed unfeasible. There were no watercourses within the near vicinity of the site, so it was proposed that the surface water be disposed of to a Thames Water combined water sewer within Avonmouth Street (in accordance with the approved drainage strategy).

Similarly, all foul water drainage would be disposed of to the same combined sewer.

The drainage strategy included the use of a green roof. It was proposed that the surface water from the roof and hardstanding areas would be discharged to private carrier pipes, connected to a geo-cellular attenuation tank from which flows would be discharged at a maximum rate of 2l/s for all storm events up to and including the critical 100 years plus 40% climate change event.

A portion of the surface water from the hardstanding would be drained via a Type C tanked permeable paving system providing treatment to runoff before being conveyed to the attenuation tank.

We worked in close collaboration with other design teams, to deliver a fully coordinated proposed external works and drainage design solution for the client.