A number of measures have been taken to address flooding issues in Derry following intense rainfall in the city over the summer.
Prior to vacating his office this week, former Regional Development Minister Danny Kennedy wrote to Sinn Fein MLA Maeve McLaughlin about the issue after the Foyle representative raised concerns.
Expressing sympathy to residents who were affected by the torrential downpours back in July, Mr Kennedy said: “While various investigations into the cause of the flooding on July 6 are ongoing, the primary cause appears to have been the sheer volume of heavy rainfall in a very short period.
“This overwhelmed the capacity of the various drainage systems and infrastructure in the area. In addition, a number of the areas affected have suffered from sewer blockages, caused by the disposal of inappropriate items within the sewerage system, in the past.”
A detailed investigation of the sewerage system in the De Burgh Terrace area is under way, while at Glencaw Park, NI Water has planned a de-silting operation and CCTV examination of the sewer network.
“NI Water also plans to replace the number of manhole covers that were dislodged due to the excessive flows in the sewerage system. These covers have been programmed for replacement with heavy duty bolted down covers to help prevent recurrence.”
The Department for Agriculture, meanwhile, has concluded that flooding in the Rossnagalliagh Park area was associated with a blockage with “an undesignated open watercourse spilling onto a potato field and flowing towards the housing development.”
Rivers Agency, he added, completed emergency works to the watercourse in July and contacted the current farmland tenant “to remind him of his responsibility under Schedule 5 of the Drainage (NI) Order 1973”.
The flooding at Little Diamond was caused by surface water from fields and roads running downhill from the Creggan area, which overwhelmed Creggan Street Mews’ drainage system.
“There are three gullies at the bottom of the street and during heavy rainfall the drainage system cannot cope with the excess flows that gather in this area,” Mr Kennedy said, adding: “Previously, the 100m high kerbs prevented the water from discharging into the adjacent properties, but the intensity of water on this occasion over-topped the kerb and entered house No 23.
“In addition to ongoing works and investigations, I have asked the inter-departmental Flood Investment Planning Group, led by my Department, to examine if any measures can be taken to reduce the risk of future flooding in this area.”