Highways Adverse Weather & Winter Service Plan

Flooding

Overall responsibility for managing flooding sits with a number of public bodies in Wales including Natural Resources Wales (Main Rivers, Coastal and Tidal), Water Authority (Sewer flooding), Ordinary watercourses (CCC Flood Defence), Ground Water and Surface Water (CCC Flood Defence).

Flooding alerts are normally issued by Natural Resources Wales and the types of alert issued are shown in the table below which also indicates the likely organisational or multi-agency response.

Where roads are flooded by extremely high tides, adjacent watercourses breaching their banks or from surface water from adjacent land, it may be necessary to ensure public safety by closing roads until the flood waters recede and allow the roads to safely be reopened again.

The highways authority is responsible for the management of water that naturally falls onto the highway surface. Our main focus is to remove surface water from the highway as effectively as possible to reduce the risk to road users. The regular cleaning of road gullies and the management of interconnecting pipes and culverts is a key method of reducing the risk of water standing on the road surface. The risk of gullies blocking due to fallen leaves is at its greatest during the autumn.

In advance of forecast periods of high rainfall Highway Teams will check known flood risk locations on the network to remove any obvious blockages in addition to advance clearing of trash grids on priority flood risk assets.

It is understood that an increasing intensity of rainfall is being experienced more frequently due to climate change. These periods of high intensity rainfall can quickly create a volume of surface water which is, for a period of time, above the capacity of the highway drainage systems. As a consequence, surface water ponding may occur for a time. This ponding will normally dissipate as the rainfall eases and the highway drains clear away the water, provided the receiving watercourse levels have receded.

Where the risk of property flooding is forecast the authority may use sandbags where they can be effective on a temporary emergency basis during flood events to redirect shallow water primarily in connection with or relating to its own highway and infrastructure assets. Property owners are encouraged to take practical steps to protect their property, and further details are contained in Carmarthenshire’s latest Sandbag Policy. 

Where appropriate sandbags will be deployed at strategic locations across the County immediately preceding a storm event. Statements will be issued by our Press Office when this occurs.

The Council should not be wholly relied upon to provide help and assistance during a flooding incident. However, there will be occasions where flooding is unexpected, or affects new areas, and the Council will help as far as its resources allow.

In more rural areas the highway drainage consists of drainage ditches alongside the roads. Roadside ditches are normally the responsibility of the adjacent landowner and should be regularly inspected and maintained by the landowner. The Highway Authority will normally have a right to discharge surface water into the roadside ditch or watercourse. Where necessary the Highway Authority may require the adjacent landowner to undertake maintenance works on a ditch to prevent a nuisance being caused on the highway (Adjacent Landowners and the Public Highway.gov.wales).