Hydrodynamic vortex separators are well-known worldwide as effective stormwater treatment devices, particularly for removing silts and sediment. In this article, we will use the SPEL Smartceptor to discuss where hydrodynamic vortex separators can be used with real-world case studies.
The CIRIA SuDS Manual (c753) states that stormwater treatment should be installed upstream of attenuation systems. This is to ensure that silt is captured and does not fill the attenuation system with silt, and reduce the effective capacity of the attenuation system. Putting treatment downstream of a flow control device may reduce the size of the treatment system; however, in the long term, the cost of dredging a pond or desilting a crate attenuation system will be much more expensive than installing a correctly sized treatment system upstream of the attenuation.
The SPEL Smartceptor has some very important features, including:
- Meets Low-Risk mitigation index within a single unit
- Good capture and retention of hydrocarbons that cannot be washed out in storm flows, thanks to the ‘clarifier pack’
- Clarifier Pack slows flow at the upper level, inducing the drop out of finer silt particles and coalesces finer hydrocarbon globules.
- A built-in bypass ensures high-flow storm events are safely bypassed and do not disturb captured pollutants.
- A single-piece unit – allowing rapid on-site installation.
- SPEL 25-Year Tank Shell Warranty
- UK performance test results with WRc Performance Declaration
- A range of sizes to accommodate treatment flows up to 400 l/s and maximum flows up to 900 l/s
- Minimal aboveground land take required (all Smartceptor models have a single access opening that can be finished at ground level with a manhole cover)
Residential/Housing Developments
Image Credit: Roma Homes
Residential/housing developments often use the SPEL Smartceptor because the CIRIA SuDS Manual (c753) categorises them as ‘Low Risk’ (see table below). Low Risk requires SuDS Mitigation to a level of 0.5 (TSS), 0.4 (Metals), and 0.4 (Hydrocarbons). As the SPEL Smartceptor has mitigation indices of 0.5 (TSS), 0.4 (Metals), and 0.5 (Hydrocarbons), the SPEL Smartceptor more than meets the required mitigation level within the single unit, making it the ideal solution.
View the SuDS Table by scrolling down this page
A recent new housing development of high-specification homes near Challock, Kent, within the area of outstanding natural beauty between Ashford and Canterbury, utilised the single-piece Smartceptor with no above-ground land take and minimal below-ground land take to meet the low mitigation requirement. Being within an area of outstanding natural beauty required that the product had very robust testing certification to give the local council confidence that the SPEL Smartceptor would satisfactorily reduce pollution.
Hospitals
Credits: East Suffolk and North Essex NHS Foundation Trust
Hospitals often have a variety of access roads/low-use traffic areas which are defined within the CIRIA SuDS Manual (c753) as ‘Low Risk’. This means the SPEL Smartceptor, with its mitigation indices of 0.5 (TSS), 0.4 (Metals), and 0.5 (Hydrocarbons) meets this low risk within a single unit. As hospitals are often very tight on space, the SPEL Smartceptor is perfect with minimal aboveground land take (only a single manhole cover).
The CIRIA SuDS Manual places hospital car parking within a medium risk pollution hazard indices. Where medium-risk pollution hazard indices are required, the SPEL ESR Stormwater Treatment Systems meet the ‘medium’ risk pollution hazard indices within a single unit and therefore are ideal for this medium-risk application.
Very large investments and developments at Colchester Hospital, including upgrades and new builds, led to new access roads that required treatment up to a low SuDS mitigation index. 3no. SPEL Smartceptor SHV200/30’s were used on three separate access roads to treat up to 30 l/s and up to a 4,000m2 catchment area each.
New Roads/Highways
SPEL Smartceptor Hydrodynamic Vortex Separators are used on highway projects, including National Highways and local councils. They are chosen because of their silt/sediment removal and retention efficiencies and for their low land take. The CIRIA SuDS Manual (c753) suggests that roads, trunk roads, and motorways should meet medium or high-risk pollution hazard indices, and if this is required, the SPEL ESR Range can meet medium risk within a single unit and can meet high risk with a small amount of extra treatment for dissolved metals.
SPEL’s wide range of products, including the SPEL Smartceptor, SPEL ESR Stormwater Treatment Systems and SPEL StormCheck flow control devices, were utilized across the full length of the A417 Missing Link project for National Highways and Gloucestershire County Council. By the end of the project, SPEL will have supplied up to 6no. SPEL Smartceptors across both the SHV200/30 and SHV300/70 models, up to a treatment flow rate of 70 l/s within a single unit.
High Rise Developments
Image Credit: JLL Residential
High-rise developments have minimal trafficked areas or large carparks due to site restraints, however, they do often have areas that are predominantly used by pedestrians but also act as access roads for vehicles and therefore require ‘Low Risk’ mitigation in line with the CIRIA SuDS Manual (c753).
The town of Chatham in Kent is very strategically located, just 40 minutes from central London. This modern development features 111 one- and two-bedroom high-specification apartments. A SPEL Smartceptor SHV300/70 was required to treat the ‘Low Risk’ stormwater run-off from the site up to 70 l/s and a catchment area of 9,333m2. The Smartceptor needed to be offloaded from the transport vehicle and then lifted across the site to its final position (see pictures). Therefore, a lightweight GRP design and a single-piece unit was ideal for this application, making the installation fast and safe.
Industrial Areas
The CIRIA SuDS Manual (c753) states that a ‘High Risk’ pollution hazard level must be met on ‘sites with heavy pollution (eg haulage yards, lorry parks, highly frequented lorry approaches to industrial estates, waste sites), sites where chemicals and fuels (other than domestic fuel oil) are to be delivered, handled, stored, used or manufactured; industrial sites; trunk roads and motorways’. Therefore, on some industrial units with high lorry usage, mitigation must be to a level of 0.8 (TSS), 0.8 (Metals), 0.9 (Hydrocarbons). In situations requiring a ‘High Risk’ pollution hazard level to be met, consultants often specify a treatment train of a SPEL ESR Stormwater Treatment System followed by a SPEL Smartceptor. The SuDS Manual states that in this situation, the downstream device will only account for 50% of its mitigation indices. Therefore, this treatment train has a total mitigation indices of 0.8, 0.6, 0.9 + (50% of 0.5, 0.4, 0.5) = 1 (TSS), 0.8 (Metals), 1 (Hydrocarbons). Mitigation indices cannot exceed 1, as this signifies 100% removal.
This treatment train was used on the DIRFT DC9 and DC10 warehouses near Rugby for 4 separate outfalls from the site, resulting in 4 no. SPEL Smartceptors being manufactured and supplied to work in tandem with 4no. SPEL ESR Bypass Stormwater Treatment Systems and treatment flow rates of both 30 l/s (SHV200/30) and 70 l/s (SHV300/70). For High-Risk areas, having certification by a respected organisation is often required for planning permission, and SPEL can offer this with our certification carried out by the world-renowned Water Research Council (WRc).
Access Roads
Similar to highway projects, access roads are often required by councils to be treated by Hydrodynamic Vortex Separators to remove and capture the silt and sediment from the access road. However, the CIRIA SuDS Manual (c753) suggests that roads, trunk roads and motorways should meet medium or high-risk pollution hazard indices and if this is required, the SPEL ESR Stormwater Treatment Systems can meet medium risk within a single unit and can meet high risk with a small amount of extra treatment for dissolved metals.
The access road to Teesworks, one of the UK’s new freeports, located in Teeside, required stormwater treatment via Hydrodynamic Vortex Separators. This access road has opened a large number of the designated Teesworks areas, allowing regeneration of the area. Due to the catchment area of the new access road, two large SPEL Smartceptors were required, the SHV400/200 and the SHV500/400. Despite their size, as these are a single-piece unit manufactured from lightweight GRP, the installation is quicker than vortex separators that must be fitted within concrete rings. As no on-site fitting work is required within the tanks, health and safety risks are also greatly reduced.
Schools/Colleges
Image Credit: placenorthwest.co.uk
Schools and colleges often have small car parking areas with infrequent changes and low-traffic roads. The CIRIA SuDS Manual (c753) in table 26.2 defines these areas as a ‘Low Risk’ pollution hazard level, and therefore, a SPEL Smartceptor is all that is needed to meet this. Low risk in the SuDS Manual requires treatment to 0.5 (TSS), 0.4 (Metals), and 0.4 (Hydrocarbons,) and the SPEL Smartceptor exceeds this with a mitigation index of 0.5, 0.4, and 0.5.
For newly built areas at Loreto College, Hulme, Manchester, the stormwater run-off from a small carpark area and the roof runoff required treatment in line with the SuDS Manual up to a pollution hazard index of low. Therefore, the SPEL Smartceptor was the perfect single product to meet this requirement.
Commercial Areas
Commercial areas are required by the CIRIA SuDS Manual (c753) to meet at least a medium-risk pollution hazard index. In commercial areas with space for a pond or similar, the SPEL Smartceptor is often used as a silt removal device placed before the pond. The CIRIA SuDS Manual, Section 23.1 states, ‘Ponds and wetlands should always be designed with suitable upstream pre-treatment systems.’ With a very small footprint and WRc-certified performance, the SPEL Smartceptor does this cost-effectively.
A new industrial development in Croft, Bromborough, required these 2no. SPEL Smartceptor SHV200/30 models, protecting downstream attenuation from silt buildup.
