The bay, located adjacent to Barry Old Harbour, is primarily a steeply sloping stone and pebble beach, with sand exposed at low water only. The beach faces south west towards the Bristol Channel, backed by cliffs at the north end, with a promenade at the south end towards Cold Knap Point and the highly urbanised town of Barry in the surrounding area. The water quality sample point is located at the centre of the bay, opposite the car park.
Natural Resources Wales is continuing to work with the Vale of Glamorgan Council and Dŵr Cymru Welsh Water to establish sources of pollution that are adversely impacting the water quality at Cold Knap Bay.
Inspections are carried out by Natural Resources Wales in partnership with the Local Authority. These are carried out pre-season (before the 15th of May) and mid season if required (during the bathing water season).
A project known as Event Duration Monitoring (EDM) is underway to install telemetry on Combined Sewer Overflows (CSOs) within 2km of a bathing water by 2020 so that Dŵr Cymru Welsh Water (DCWW) know when the CSOs are operating and can work to reduce spills. Fifteen CSOs near Cold Knap Barry are included in the project.
Dŵr Cymru Welsh Water has invested a significant amount of money to upgrade the sewerage infrastructure in the Barry catchment, under The Asset Management Programme. The five year rolling programmes are developed by Natural Resources Wales and Dŵr Cymru Welsh Water to bring about water quality improvements and comply with environmental legislation and European directives.
Dŵr Cymru Welsh Water’s Barry Town West Works, near Cold Knap normally transfers effluent to Cog Moors Sewage Treatment Works to the east of Barry for treatment. In high flow conditions, this treatment works discharges directly to the Bristol Channel, via long and short sea outfalls, located off Cold Knap Point, to the east of Cold Knap Bay. The effluent discharged is screened to minimise its environmental impact and to protect the bathing water quality.
Natural Resources Wales and the Vale of Glamorgan Council have been working together to improve the bathing water quality at Cold Knap for a number of years. Information is being shared to develop a combined approach to resolve issues impacting the water environment, such as rectifying misconnections which could be affecting the water quality of the streams flowing through Porthkerry Park, which outfall onto Bullcliff Rocks to the west of the bay.
Modern sewerage systems have two separate systems, one takes foul sewage to sewage treatment, the other takes rainwater runoff through surface water drains to rivers, lakes and the sea. Misconnections occur when waste water pipes are plumbed into surface water drains instead of the foul water sewerage system. This can give rise to pollution when the waste water is discharged directly to the environment through the surface water drain. For example, a washing machine or toilet may be incorrectly plumbed so that it discharges to the surface drain rather than the foul sewage drain.
Phytoplankton (microscopic algae) naturally increase in number at certain times of the year. This process is known as a phytoplankton bloom. These algal blooms can occur at any beach during the bathing season and are usually noticeable by a surface scum. This beach does not have a history of such blooms.
Streams are typically affected by sewage or industrial run off from further up the catchment. Cold Knap Bay can be influenced by the fresh water of the River Cadoxton. There are also a number of small streams (Nant Talwg, Cwm Barri Brook, Whitelands Brook and the Knap feeder) and surface water drains which discharge to the sea in and around the bay. These can intermittently be a source of reduced water quality, after heavy rainfall depending upon the prevailing wind and tidal conditions.
Natural Resources Wales samplers make visual observations of the beach at every visit. This includes assessments of sewage debris, animal faeces, litter and oil or tar. At Cold Knap Barry, data are available for the four year assessment period from 2015-2018. Sewage debris was observed in trace amounts on less than ten per cent of occasions. Trace amounts of animal faeces were noted at the site on a minority of occasions. Trace amounts of litter were observed at the bathing water the majority of the time and in greater amounts on less than ten per cent of additional occasions. Oil and tarry residues were not noted at this site.
Natural Resources Wales continues to work with private owners regarding potential pollution sources to the bathing water. This work involves where necessary, advisory mail drops, dye tracing, misconnection surveys and face to face meetings.
Poorly maintained private sewage treatment facilities could be a source of pollution, therefore the registration of all private sewage systems in Wales was required by 30 June 2012. The primary aim of this exercise was to provide increased protection for the environment and sensitive features such as bathing water beaches. Where properties are identified in the catchment that are not on mains sewerage, Natural Resources Wales will endeavour to ensure registration has been made.
The natural drainage (hydrological) catchment surrounding the bathing water is highly urbanised with commercial buildings in the immediate vicinity. The River Cadoxton meets the sea four kilometres east of the bay and may influence bathing water quality, depending on tidal currents and weather conditions. The River Cadoxton drains a large and diverse catchment. In the lower reaches, there is a combination of large residential areas and heavy industry, along with several small industrial estates. Towards the top of the catchment the land is largely rural, which is not intensively farmed.
Seaweed (macroalgae) and phytoplankton (microscopic algae) are a natural part of the marine and freshwater environment. Below we note whether these have been recorded in quantities sufficient to be a nuisance.
The majority of sewers in Wales are “combined sewers” and carry both sewage and surface water from roofs and drains. A storm overflow operates during heavy rainfall when the sewerage system becomes overwhelmed by the amount of surface water. The overflow prevents sewage from backing up pipes and flooding properties and gardens. An emergency overflow will only operate infrequently, for example due to pump failure or blockage in the sewerage system.
Heavy rain falling on pavements and roads often flows into surface water drains or highway drains, ending up in local rivers and, ultimately, the sea. The quality of bathing water may be adversely affected as a result of such events.
It is Natural Resources Wales' role to drive improvement of water quality at bathing waters that are at risk of failing European standards. It is natural for water to run off the land to the sea. Water quality at a bathing water is dependent upon the type and area of land (the catchment) draining to the water and the activities undertaken in that catchment. The following sections serve to highlight potential sources of pollution, conditions under which they may arise and measures being put in place to improve water quality.