Tag Archives: Drainage

Application for Discharge of Drainage Condition

Application for Discharge of Drainage Condition

We have recently been engaged to discharge drainage conditions in Wiltshire. The planning approval contains 2no. drainage related conditions that we are applying to remove at the same time.

What does the condition look like?

“No development shall commence on site until a drainage strategy has been submitted
to and approved in writing by the local planning authority. The drainage strategy shall
include, as a minimum, the following information:
– Calculations and drawings for the drainage system design showing designated holding areas and conveyance routes based on no flooding on site for a 1 in 30 year rainfall event.
– Calculations and drawings for the drainage system design showing designated holding areas and conveyance routes based on no flooding on site for a 1 in 100 year plus climate change rainfall event in respect to a building (including basement) or utility plant susceptible to water within the development;
– Calculations which demonstrate that the required 20% betterment against greenfield rates has been achieved for all storm events between the 1 in 1 year and the 1 in 100year return period storm events.
– A clearly labelled drainage layout plan showing the pipe networks and any attenuation ponds. The plan should show any pipe node numbers referred to within the drainage calculations.
– A plan showing the cross sections and design of any attenuation pond and its components”

What is our response to that?

Our response to this will include a custom written report that sets out the requirements step by step, using plans and calculations.

How we can help.

If you need a planning condition related to drainage discharged then please do contact us. We provide a free of charge 15 minute consultation to help understand your requirements. Our reports are kept as simple as possible, and are typically well received.

Worked Example of Soakaway with Costings

Worked Example of Soakaway with Costings

This is a fairly inaccurate walkthrough of a soakaway design to BRE 365 and an estimation of costs for installation of the designed soak away.

Design

Provided here is a worked example of a soakaway designed to BRE 365.

The soakaway is receiving  water from a roof of 323m2.

The site is set of sandy clay soil. With a permeability of 9X10-6 (Reference Value)

1:100 year rainfall event. With 40% climate change allowance.

Size of Soakaway is 22 m3.

Soakaway dimensions are 2 meters by 11 meters. And consists of crate type modular system.

Install

Below costs, for crate soakaway:

  • Crates: 110 crates at £30 each. £3300
  • Digger: £500
  • Soil Disposal: 40 tons @ £10 ton. £400
  • Pipe Work: £500
  • Labour: £2000

Total cost: Approximately £7000, with VAT on top probably.

Case Study