ES9 - Filtration of pollutants

Rain gardens are defined as small-scale vegetated gardens used for storage and infiltration. The term ‘rain garden’ is often used interchangeably with ‘bioretention area’ (although the latter could also be applied more loosely to other measures such as filter strips or swales). 

Channels and rills are shallow open surface water channels incorporated in to the start of a SuDS train. They collect water, slow it down and provide storage for silt deposited from runoff. They can have a variety of cross-sections to suit the urban landscape, and can include the use of planting to provide both enhanced visual appeal and water treatment. 

The main role of channels and rills are to collect runoff at the start of a...

Riverbank represents both natural and man-made features following the river flow. In the past, lots ofmany artificial banks were built with concrete or other types of retaining walls, thus restricting the natural movements of rivers, leading to river degradation, increased water flow, increased erosion and reduced biodiversity. 

Filter strips are uniformly graded, gently sloping, vegetated strips of land that provide opportunities for slow conveyance and (commonly) infiltration. They are designed to accept runoff as overland sheet flow from upstream development and often lie between a hard-surfaced area and a receiving stream, surface water collection, treatment or disposal system. 

Filter strips are generally planted with grass or other dense vegetation...

Infiltration trenches are defined as shallow excavations filled with rubble or stone. Their function is to facilitate the natural process of infiltration into the surrounding soils from the bottom and sides of the trench, thereby enhancing the soil's inherent capacity for drainage. Ideally, they should receive lateral inflow...

Green roofs are multi-layered systems that cover the roof of a building with vegetation and/or green landscaping over a drainage layer. There are two types of green roof: 

• Extensive green roofs cover...

Soakaways are buried chambers that store surface water and allow it to percolate into the ground. They are typically square or circular excavations either filled with rubble or lined with brickwork, pre-cast concrete or polyethylene rings/perforated storage structures surrounded by granular backfill. The supporting structure and backfill...

According to the Convention on Wetlands (1971), a wetland is an area of marsh, fen, peatland or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt, including areas of marine water the depth of which at low tide does not exceed six metres. 

Wetlands play a crucial role in regulating the global climate and are natural biofilters for pollutant removal, nutrient...

Buffer strips and hedges are natural or semi-natural vegetated features integrated into agricultural and semi-urban landscapes to enhance ecological and hydrological functions.

Buffer strips are areas of natural vegetation cover (grass, bushes or trees) at the margin of fields, arable land, transport infrastructures and water courses. They can feature various combinations of vegetation, from simple grass to mixtures of grass, trees,...

Controlled traffic farming (CTF) is an agricultural system which confines all machinery loads to the least possible area of permanent traffic lanes. Current farming systems allow machines  to randomly traverses the field, compacting around 75% of the area within one season and at least the whole area by the second season. Soils don’t recover quickly, taking as much as a few years. A proper CTF system on the other hand can reduce...