Vale of Glamorgan council decided to install three Hydro Filterra™ units from Hydro International at the Business Service Centre (BSC) car park to meet Sustainable Drainage Systems (SuDS) standards and provide urban planting and landscaping within construction of a new car park.“Features like swales and reedbeds were not feasible to introducing more biodiversity, as there was not enough room in this typical urban location which is surrounded by buildings and infrastructure,” points out Vale of Glamorgan Drainage Engineer Keith Sulsh.“The three Hydro Filterra™ units enabled us to meet Environment Agency requirements for removing pollutants from stormwater run-off before discharge via the storm sewer into the adjacent docks. Hydro Filterra™ combined several different SuDS features within one system, which was not met by any other solution the council looked at.”The Hydro Filterra™ system looks like a normal tree box from the surface with suitable shrubs or a tree protruding through a decorative grating in a typical concrete slab at pavement level. Underneath, a concrete container with a mulch layer, and unique soil filter medium provide for effective and consistent stormwater treatment and attenuation. Hydro Filterra™ is connected to a surface water drain, infiltration or soakaway system via an underdrain system.The Hydro Filterra™ bioretention system is a self-contained unit with high retention rate for solids, heavy metals and oils and grease, thanks to the vegetation and special growing medium. Its footprint is typically up to 50 times smaller than other standard bioretention systems, and requires little maintenance.The council decided to review surface water drainage at the BSC Car Park when a previous design using porous paving was proving unsatisfactory. The Hydro Filterra™ units provided an attractive solution that was sympathetic to the need to improve the landscaping and amenity of the area.As the overall parking is for 63 cars, Environment Agency requirements on pollution are strict, so water quality treatment must be very effective. The BSC car park is divided into three connected areas, which added complexity to the falls required for drainage. Final discharge from the car park is via the surface water drainage system into Barry Dock. Requirements from the Association of British Ports, who are responsible for the marine environment of the docks, were that no additional pollution should be allowed to jeopardise the marine ecosystems.
