Full application requirements

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Application details

Application number.
Site address.
Site co-ordinates and/or What3Words reference.
Site area in hectares.
Existing site usage.
Proposed development.
Existing site plan.
Proposed development plan/masterplan.

Flood Risk

Sufficient information should be submitted which shows, in principle, that the development will be safe from flooding for its lifetime and will not increase flood risk elsewhere. The minimum we require is:

A plan showing the flood zones of the site.
A plan showing the surface water risk of the site.
A Flood Risk Assessment which meets the requirements of the Environment Agency and DEFRA as set out in their online guidance: Flood risk assessments: applying for planning permission - GOV.UK.
Outline information into how safe access during the design flood and emergency egress during the extreme flood could be achieved as part of the development.

We advise applicants that flood risk from all sources of flooding should be treated consistently, and no single source of flooding should be considered more important than another. In line with national guidance flood risk assessments should consider the design flood event from all sources as well as greater frequency flood events, especially the 1:30 flood event.

In areas of increased flood risk the level of detail required is likely to be significant. If any development, including level changes, are proposed within the flood extents then site specific flood modelling is likely to be required. We advise applicants to engage in pre-application discussions with the LLFA to ensure any modelling undertaken meets requirements.

It is also advised that applicants engage in pre-application discussions with the LLFA if their development incorporates more or highly vulnerable development and/or the site is subject to increased flood risk from any source, and this has not been undertaken at an earlier planning stage.

Drainage

At full application stage we expect applicants to submit a largely complete drainage design which shows how the proposed development shall manage surface water drainage in line with national and local drainage guidance and policies.
We advise that infiltration drainage is generally difficult to achieve due to the poor soakage potential of much of our geology and high groundwater levels found across the county. Any proposed use of infiltration drainage will therefore need to be fully evidenced with winter groundwater level monitoring results and infiltration testing.
As a minimum we would expect the following information/ plans to be presented as part of a drainage design:

Topographic survey.
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.
Drainage calculations, with drainage features identifiable on both calculations and plans.
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.
Outline information into how surface water exceedance flows shall be managed to ensure no internal flooding occurs on site, and flood risk is not increased offsite.
An initial 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.
Evidence that consideration has been given to maintenance and management of the proposed drainage system considering the proposed development and other services on site. This should include as a minimum:
- Plans showing the proposed development and the easement/maintenance corridors for all onsite services (retained, existing and proposed).
- Outline information into the proposed means of maintaining each drainage element including potential responsible parties (i.e. adoption by water authority, private maintenance and management company etc.).