Drainage & flooding
Mar 21, 2023
Much has been written about possible flooding due to the construction by Curo. Reports that they have commissioned have said that flooding on the site will not be an issue. However as we have repeatedly stated, this is not the prime concern.
Tom Clifford has once again tackled the planning office and it seems that the issues he raised are being now taken seriously. The following is aa letter he wrote on 2nd March.
FAO D. Roberts Drainage & Flooding Team (LLFA)
I write in reply to your consultation response dated 21/2/2023 regarding the above planning application. Whilst I appreciate you have been asked to comment on the specifics of the surface water drainage proposals within the boundary of the proposed development I am concerned that as LLFA you have no comments to make regarding the wider flooding risk the proposed development poses.
I understand that SUDS and swale will discharge into the ditch on the eastern boundary of the site. This ditch is not engineered or maintained and in the past carried the run-off from Bath Road. The ditch, in turn, flows into a culvert. This culvert is known to be damaged sufficient to restrict flow, with, as far as I am aware, an unknown riparian owner; yet the applicant assumes the culvert will be repaired by the riparian owner to provide free-flow. This approach to minimising the risk of downstream flooding from the development seems pretty cavalier and is something I would have thought the LLFA, given its role in flood prevention, would have some concerns about. (As I am sure you are aware the bottom of Keels Hill already becomes inundated following wet weather events.)
I also note that the applicant is proposing to carry out works under the auspices of the Council, presumably in its capacity as Highways Authority, on drains running under Keels Hill/ Firgrove Lane. To residents like me, this suggests that the wider infrastructure required to manage surface water from the development is inadequate - perhaps to the degree that the proposed development is inappropriate. It has never been established that the wider drainage infrastructure will cope and, indeed, the issue was fudged when the Reserved Matters application was determined.I would appreciate the view of the LLFA on the wider flood risk the proposed development may pose - not its view on the drainage proposals within the boundary of the site
The LLFA have now responded. It does not address the suitability of the downstream infrastructure to receive the surface water drainage but they have noticed that the channel the on-site discharge point feeds into is of smaller dimensions than the discharge point, so, an instant surface
flooding risk(?) They have asked for further information on the size of the receiving channel. Cumulatively, all these surface water issues may
start to add-up.
The Drainage and Flooding team require some more information on this proposal.Regarding the SFA6 C Headwall drawing please can the position of this be marked on to the drainage drawing, to confirm its location.The Outfall swale is showing as 1m wide with a minimum height 0.5m side slopes 1.3m which appears to be discharging into the existing water course which is smaller with a depth of 300mm and 1.2m side slopes.Please can you highlight the whole section of ditch that you are proposing to reprofile.
Thank again to Tom for his work on this.