Discharge of conditions application requirements
Flood Risk
It is unusual to manage any flood risk elements of a development via a planning condition. Any flood risk condition placed on a planning permission will therefore have bespoke requirements.
We advise applicants to engage with us via the pre-application process to ensure all relevant information is provided to address the needs of the condition.
Drainage
At discharge of conditions stage a complete, for construction, detailed drainage design should be submitted by the applicant, and should include:
- Topographic survey (existing) and proposed level plan.
- Details of existing drainage of site (man-made and natural).
- Details of site and ground conditions including contamination and geo-hazard (such as ground stability).
- Groundwater monitoring and infiltration testing (to BRE365 standard) will be required, unless it can be shown that these are not required. We would advise that due to generally high groundwater across the county, winter groundwater monitoring will be required for most sites regardless of drainage design to ensure excavations consider potential groundwater ingress.
- Existing and greenfield runoff rates and volumes.
- Proposed runoff rates and volumes (based on finalised development layouts and landscaping plans).
- Plans showing the proposed drainage system, including component details such as pipe diameters and ground and invert levels.
- Long and cross sections of the proposed drainage system, showing finished levels, cover levels, invert levels, gradients, and referenced drainage features.
- Drainage calculations, with drainage features identifiable on both calculations and plans.
- Details of all assumptions, design criteria and emptying times should also be included.
- A drainage design report which demonstrates compliance with the national Planning Practice Guidance, the non-statutory technical standards and any relevant Local Planning Authority drainage policies.
- Details into how surface water exceedance flows shall be managed to ensure no internal flooding occurs on site, and flood risk is not increased offsite. As a minimum this should include:
- Evidence all of watercourses/ditches and surface water flow routes on site have been maintained post-development.
- Plans showing proposed surface water exceedance flow routes and any areas where exceedance flood waters are designed to be stored.
- A plan showing the pre and post development surface water flow routes across the site to ensure flood risk offsite is not increased.
- An assessment of offsite flood risk impacts, demonstrating how they shall be managed to ensure development does not increase flood risk elsewhere.
- Drainage system outfall/connection information including locations and agreements in principle from all relevant authorities/asset owners.
- Should access to third party land be required to facilitate connection then evidence of an agreement in principle for this will also be required.
- Design specific construction details for all drainage elements, including storage and flow controls.
- A maintenance and management plan for the proposed development which should include:
- Evidence that consideration has been given to maintenance and management of the proposed drainage system considering the proposed development and other services on site.
- Plans showing the proposed development and the easement/maintenance corridors for all onsite services (retained, existing and proposed).
- Details of the proposed means of maintaining each drainage element including responsible parties (i.e. adoption by water authority, private maintenance and management company etc.).
