The use of Sustainable Urban Drainage Systems (SuDS) best management practices should be an integral part of any development’s surface water management strategy. This should provide a basis for replicating the response of a catchment and its surfaces by mimicking, to some extent, the behaviour of surface water on the developed site as if it had remained undeveloped.
The successful implementation of a SuDS scheme should consider a combination of natural and proprietary techniques, complemented by traditional drainage methods, where appropriate. It is essential that planners, designers, installers and operators of SuDS drainage systems take into account the importance of whole life maintenance and the use of suitable components that deliver authentic sustainable drainage performance and longevity.
The Sustainable Urban Drainage Systems philosophy is underpinned by the water “Management Train”. The Management Train applies Sustainable Urban Drainage System techniques in series and is based on:
The Management Train can be divided into the following processes:
MPA Precast Drainage Association members offer a wide variety of proprietary Sustainable Urban Drainage System components and systems suitable for use within a sustainable drainage system. These are listed in the table below indicating their functions within the Management Train.
Rigid pipeline system with flexible joints for conveyance of stormwater and storage / attenuation, available with optional dry weather flow channel and side entry manhole access. Perforated version enables stormwater to percolate into the ground.
Circular concrete pipes have a circular cross-section measured at 90 degrees to the direction of flow and are typically used as part of a drainage system for the conveyance of foul and surface water. They can also be used for attenuation storage and the subsequent controlled release of surface water in sustainable drainage systems (SuDS). Other uses include culverting of watercourses where construction can create an obstruction to the natural flow path.
Precast concrete pipes are classified structurally as rigid systems. They have flexible joints which enable ground movement to be accommodated along the length of the pipeline.
Elliptical pipeline system for conveyance of stormwater and storage / attenuation with minimal cover requirement, available with dry weather flow channel and side or top entry manholes.
An elliptical concrete pipe has an elliptical cross-section and is typically used as part of a drainage system for the conveyance of foul and surface water. It can also be used for attenuation storage and controlled release of surface water. Elliptical concrete pipes can be used with the major axis (widest part) laid horizontally or vertically and are typically used in situations where a traditional circular pipe may not provide the required hydraulic performance or where there are limitations on construction depth or width, for example due to other services located adjacent to the pipe run.
Precast concrete is strong and highly durable, providing asset owners with a reassuringly long service life and low whole life costs.
Precast concrete is a low carbon, sustainable material made from local materials that can be recycled end of life. Elliptical concrete pipes can be designed to withstand full highway loadings and constructed with minimal depth of cover.
When laid with the major axis vertical, secondary inverting with a low flow channel may not be necessary. In common with circular precast concrete pipes, a full surround of granular material is not always required, resulting in reduced installation costs and lower environmental impacts.
"Egg-shaped" pipeline system with integral dry flow channel. Higher velocity at low flow depths compared to circular pipe providing reduced risk of siltation.
Ovoid pipes are "Egg-shaped" elements used to create a pipeline which can be used in drainage systems. In some situations, they may offer benefits over traditional circular pipes of equivalent full bore capacity as they have higher velocity at low flows, which can reduce the risk of siltation and blockages.
Ovoid pipes are common in old Victorian brick‐built sewerage systems and in some cases, precast concrete ovoid pipes can be used to match or replace parts of the existing sewer network.
Modular tank systems using precast base, floor and roof panels.
Modular tanks are generally used below ground for the storage of foul and surface water. They consist of prefabricated sections that can be assembled on site and configured to meet the layout of the design. The tanks are supplied complete with precast concrete base, wall and roof panels, which can be solid or slatted to allow water inflow.
In choosing an appropriate tank system, the specifier should consider structural design, water quality requirements, hydraulic design, installation cost and whole life cost, space constraints, ease and speed of construction, sustainability, maintenance requirements and asset service life.
Precast concrete modular tanks are available with a range of fittings.
Precast Concrete Modular Tank applications include:
Off-site, watertight solution pre-benched and configured to required inlet/outlet orientation.
Precast concrete manholes are an access chamber designed for man-entry. They are used to inspect and maintain an underground utility network, such as a drainage system.
Manholes are typically located where drain lines change direction, size or slope, and are spaced apart to allow for efficient work. Manholes may be located at boundaries, where traffic loads vary, and other demarcation locations.
An effective manhole needs to be safe, quick and efficient to install and remain watertight and structurally sound over a long asset life.
Precast manhole base systems are supplied with circular bases pre-configured with main channel, benching, inlet(s) and outlet. Manufactured with thicker walls, the cavity ring provides a high-quality off-site solution that reduces construction costs, installation time, environmental impact and improves performance.
Precast box, base and cover slab in a range of sizes and loading categories.
Perforated chamber which may be open void (providing storage) or contain filter medium (providing treatment) to facilitate percolation of stormwater into the ground.
Soakaways are below ground configurations designed to allow surface water to infiltrate into the ground. Typically, excavations are filled with aggregates or other filter media, often encased within a chamber or tank with perforations, that enable the water to soak effectively into the ground. The water must pass into the ground quickly enough to cope with the amount of rainfall anticipated in the design. The soakaway should be located in an area that will not cause problems with foundations or other structures.
Precast concrete soakaways are strong, robust and proven with a long service life.
They can provide easy access for maintenance.
Off-site solution with pre-installed flow control device such as penstock, non-return valve, weir wall, orifice plate, vortex flow regulator.
Flow control chambers are part of a surface water drainage system and can be used to manage discharges from new developments. They may also be retro-fitted to existing systems. The chamber accommodates a choice of flow controls and combinations and is designed to mitigate the risk of flooding, erosion and environmental damage.
Designed to receive storm water runoff from paved surfaces and first-line gravity separation of silt.
As the name would suggest road gullies are a drainage component designed to discharge surface water from roads and motorways. They can form part of a surface water management system. They are set below the road surface and located adjacent to the kerb side. Gullies are a flexible solution for a wide range of applications. This includes car parks, other hard standing areas and also form part of a sustainable drainage system (SuDS).
An open grating and frame assembly is constructed within the drainage surface over the gully. Intercepting surface water runoff that then passes into and through the gully.
Road gullies are a drainage component that have an outlet connection above the base of the unit. This allows silt and other solid material to separate out and collect in the sump below the outlet. This helps to prevent blockages occurring downstream within the pipeline. It also helps remove some pollutants that can attach to the silt particles collected in the sump.
In comparison to domestic gullies a road gully is created to be a lot more robust allowing it to withstand the heavier trafficked environments in which they are installed.
It is important that road gullies are regularly maintained to ensure optimum efficiency.
Enhanced capacity road gully for first line separation of silt and surface water runoff from surfaces prone to flooding.
A road gully by definition is an outside water drain pipe that's designed to discharge surface water. Rain water flows off the road surface into the road gully and then through underground pipes, sewer systems, soakaways, catchpits or roadside ditches, and on occasion directly into watercourses.
A high capacity road gully has an enhanced capacity for first line separation of silt and surface water runoff from surfaces prone to flooding.
Gully pre-fitted with filter for removal of oils and silt.
Chamber for silt capture, litter and some oils.
A hydrodynamic vortex separator is designed for the effective capture and retention of insoluble particles carried within surface water runoff such as silt, other surface contaminants and some oils. Its design delivers separation across a range of flows in a smaller footprint than conventional gravity separators. It is normally installed within a special chamber at the head of a drainage system and is designed to reduce the amount of solid material passing into the main sewer, thus preventing the risk of reduced hydraulic capacity and blockages occurring within the network and to limit the transport of pollutants passing through the system.
A variety of pre-configured chambers for removal of foreign objects and pollutants such as litter, oil, grease, silt and heavy metals.
A variety of pre-configured chambers for removal of foreign objects and pollutants such as litter, oil, grease, silt & heavy metals.
For the gravity separation of debris and silt to prevent it passing downstream.
Catch Pits are access chambers for surface water drainage systems with an integral sump below the outlet invert level to allow for the collection and settlement under gravity of silt and other solid matter washed from the drainage catchment surface. As such, they can help reduce downstream blockages.
Catch pit pre-fitted with filter for removal of oils and silt.
Inlets and outlets, available with flap valves and grills, connecting swales, ponds, detention basins, etc to underground pipes.
A concrete headwall is typically an outlet from a sewer that allows flow from upstream pipework to discharge into an open watercourse, such as a river, pond, swale and culvert.
Concrete headwalls may also be used as inlets to surface water management systems receiving flow from a watercourse or open channel and conveying the flow downstream through an underground pipe.
To protect embankments from erosion.
Integrated gasket joint and excellent flow characteristics for surface run off and below ground applications.
For shallow and deep channel applications.
Range of sizes. Available with optional dry weather flow channel.
A box culvert is a monolithic, flat-sided precast concrete structure with walls at 90 degrees to the floor and roof. Box culverts were introduced to provide an easily-installed conduit for culverting of watercourses where construction can create an obstruction to the natural flow path. Box culverts can also be used for attenuation of surface water as part of a sustainable drainage system (SuDS), horizontal tunnels and subways, sewers and access shafts. Smaller box culverts can also be used for dry networks including cabling.
Box culverts are available in many different size and shape configurations. Square or rectangular units can be used as single or multi-unit runs, giving excellent structural and hydraulic performance. Extensive design possibilities can be achieved with the use of end walls, access points, vent holes, inlets, outlets, double rungs, splayed ends, starter bars and threaded sockets, a range of different inverts, low-flow channels and dished inverts. Cover slabs can also be supplied separately.
Domestic and commercial rainwater harvesting systems.
Rainwater Harvesting Tanks provide storage of surface water arising from domestic, commercial, industrial and agricultural developments that can be subsequently used for a range of general non-potable applications. Rainwater harvesting can help relieve the demand for clean water on our water infrastructure and can help reduce flood risk in overloaded drainage networks.
Rainwater harvesting pre-tank for leaf and grit removal.
Domestic and commercial grey water recycling systems.
Information sources to help plan, design and implement sustainable drainage.