Proposed flood relief barrier / embankment to protect housing development built on the floodplain of the Carrowbeg
https://consult.mayo.ie/en/consultation/part-8-flood-relief-scheme-westport-cois-abhainn-ashwood
The planning application is for a proposed flood relief scheme on the Carrowbeg River located at the Cois Abhainn and Ashwood Glade housing estates in Westport, Co. Mayo.
The key components of the proposed works include the following:
-Demolition and removal of existing external steps.
-Construction of a flood relief wall.
-Construction of a flood relief embankment.
-New pedestrian access tracks, including drainage
The proposed wall will be 65m in length, will extend to a height of 1.7 metres above ground level, and will be set back approximately 6m from the Carrowbeg River embankment.
A 180m long earthen embankment, 1.2m in height, will be constructed between the housing estate at Ashwood glade and the Carrowbeg River (approximately 50m south of the proposed wall). This embankment will be set back a minimum of 9m from the river
The flood relief wall will typically be constructed as follows:
-Precast Concrete piles or steel sheet piles will be driven into Made Ground/alluvium to bedrock or a suitable depth to support design loads.
-High tensile steel reinforcement will be fixed in accordance with the designer’s drawings & schedules.
-Formwork will be erected around the steel cage.
-Concrete will be placed using a concrete pump and compacted using vibrating pokers to the levels and profile indicated on the drawings.
-Upon completion of the concreting works the wall will be covered and allowed to cure
-Excavated soils will be stockpiled for off-site disposal/recovery at an appropriately licensed facility
The flood relief embankment will typically be constructed as follows:
-The embankments will be constructed by stripping the topsoil within the embankment footprint and placing low permeability clay soils to the required flood defence level.
-Imported clay soils will be clean and from a known and reputable source. The imported soil will be chemically suitable and free from propagules of aggressive weeds and foreign objects.
-Topsoil will be placed on top of the embankment and seeded.
-Excavated soils will be disposed/recovered off-site at an appropriately licensed facility
AA Screening Report
Notes
There is no information available with the Part 8 application that indicates that the proposed development will not impact on properties downstream
Submissions
There is no clear rational as to why one area will receive a wall and the other an embankment.
I do not wish a scheme to be constructed that will send the flooding problem elsewhere along the Carrowbeg River i.e. to existing properties that have been built long before Ashwood/Cois Ahhainn. Did the planning application for these developments not investigate potential flood risk in the first instance and mitigation proposals, and if so, have these not worked? If that is the case then I would suggest that there may be serious further risks of flooding should any additional development be permitted along this river. I note that the Convent grounds are being proposed for housing. This again will aggravate the problem due to concretion runoff.
Note: appears that local authority have given permission for more houses on this flood plain
Mayo County Council Planning Application Reference Number: 19442
https://www.eplanning.ie/MayoCC/AppFileRefDetails/19442/0
CONSTRUCT 16 TERRACED 2 STOREY HOUSES IN TWO BLOCKS A & B. THESE WILL REPLACE 18 DUPLEX/APARTMENT BUILDINGS PREVIOUSLY GRANTED UNDER P04/48 AND 10 TERRACED UNITS PERMITTED UNDER P12/24, ALSO REVISIONS TO INTERNAL ACCESS, PARKING, LANDSCAPING, FOOTPATHS AND ALL ANCILLARY SITE WORKS
