Howth Flood Relief Scheme

Howth Flood Relief Scheme

ByrneLooby was appointed to prepare a preliminary report to assess the flood risk on Howth peninsula and to recommend viable sustainable solutions to address and mitigate the flood risk.

The Brief included the entire peninsula of Howth, with the exception of the Offington Area which was assessed in advance under another Scheme. ByrneLooby met with and received submissions from residents, undertook CCTV, manhole, flow, rainfall and topographic surveys, built a robust hydraulic model of the catchment and undertook a comprehensive hydraulic analysis to establish the most at risk areas subject to pluvial (stormwater) flooding in Howth.

The hydrological review established that previous flood events occurred when significant volumes of rainfall occur in a short period. In total, it was found that there are approximately 44 properties at risk of flooding.

Howth Flood Relief Scheme

Our Role

Our solution was cost beneficial and there was no significant risk to the environmental sites in the vicinity of Howth. These are outlined below;

1)Construct 258m of new storm drain to remove stormwater flows from combined sewer in Nashville Park & Kilrock Road and upgrade 124m of existing storm sewer.

2)Construct 350m of new storm drain (750mm diameter) along Howth Road/Harbour Road to alleviate flooding in vicinity of the DART station.

3)Construct a cross connection between the existing siphon and the overflow from the pumping station which discharges to the east of the Bob Davis culvert and the public toilet on Claremont beach to alleviate flooding on Howth Road. Upgrade the storm drain network to the west of the Bob Davis culvert to 375/450mm diameter pipework and install a non-return valve on the overflow pipeline coming from the pumping station.

4)Implement short/immediate term measures to provide simple cost effective solutions as follows:
a. Install outfall non- return values at low lying outfalls at;
b. install non-return valves on the domestic foul water connections known to flood at Balkill Road.

5)Implement local kerb raising to direct overland flows at Kilrock Road.

6)The existing stone culvert along Main Street has been observed to be in poor structural condition with a least two known collapses in recent years. A structural condition assessment should be undertaken and if necessary a scheme implemented prepared to replace the culvert;

7)Full CCTV of areas shown to have a flood history to rule out structural/maintenance issues.

Howth Flood Relief Scheme 1