Flood Risk Assessment

The Site
The site contained an existing residential property with hardstanding drive / patio areas and a soft landscaped rear garden with levels falling away from the property towards Dollis Brook, a tributary of the River Brent.

An initial review of the EAs flood maps revealed large areas of the site to be located within Flood Zones 2 and 3, thus requiring a Flood Risk Assessment to support the planning application.

JNP Group Involvement
JNP Group accurately established the extents of the floodplain by obtaining the EA modelled flood levels and plotting against site topographic survey information.

Based on this accurate floodplain data JNP Group:-

• Provided advice on the implications of national guidance (PPS25) on the planning application.
• Provided guidance on site layout and levels with relation to flood extents.
• Designed a flood compensation scheme which set levels around the proposed layout and mitigated for an increased building footprint within the floodplain.
• Undertook a preliminary assessment of surface water drainage and set criteria for management of surface water runoff from the development.
• Demonstrated safe means of escape from the development during flood events.
• Undertook discussions with the EA to secure pre-planning approval of the above.

These works enabled JNP Group to provide a Flood Risk Assessment which satisfactorily demonstrated that the site could be developed with no increased risk of flooding on or off-site.