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Surface Water Drainage


What is a Linear Drainage System?

Swarm Aqua® is known as a linear drainage system. This is typically a channel drainage that is mostly uninterrupted at the surface level, so rather than point drainage (like gully points or peaks and troughs), the drainage channel presents a much larger orifice for interception along its length.
Channel gratings work in a similar way, however linear drainage systems are usually fixed in place, where grating systems have a removable top that can be used as cleaning points. Linear drainage channels are usually cleaned by either jetting or rodding from an access point. The nature of a fixed-in-place system means that removable parts are not damaged, lost or stolen.


Where can I use a Linear Drainage System?

Swarm Aqua® is available in a range of sizes from 100mm-375mm bore channel. Manufactured from HDPE twinwall pipe, and can be installed in concrete, asphalt or block paved areas requiring surface water drainage, Swarm Aqua® can be installed almost anywhere that may need drainage or is susceptible to flooding.


What load ratings can Swarm Aqua® cater for?

Swarm Aqua® has a ductile iron top section that is both heel safe and unobtrusive. This part has been externally verified to reach a test load of F900kN (90T). Once installed with a full concrete surround and following our installation guidelines, Swarm Aqua® has been externally verified as a whole to cater for loadings of up to F900kN (90T). Please ask for more details regarding reinforcement details.


Can I use Swarm Aqua® as part of a sustainable drainage system?

EJ is proud to advertise our partnership with JFC Civils. EJ are able to design and supply attenuation solutions and flow restriction valves to work within sustainable and flow restricted sites. By combining Swarm Aqua® surface water drainage with these products, it is possibly to meet even the strictest of demands.


How much surface area can Swarm Aqua® drain?

Swarm Aqua® is specifically designed for each project (which is a service that Swarm Water Management® can provide free of charge), however due to the capacity of the largest sizes it is possible to drain well in excess of 10,000m2 in a single run of 50-100m. Typically the maximum distance water will be expected to travel above ground is 30-50m before it is intercepted and removed from the site by the drainage network.


When do I need to use a combined box or chamber in a Swarm Aqua® system?

Combined Boxes by EJ are supplied for Swarm Aqua® channels. For channels 100-300mm wide a small combined box is used and a 150mm deep, 450x450c/o grating is supplied. For channels 375mm wide a large combined box is used and a 150mm deep, 600x600c/o cover is supplied. For 600mm channels a chamber must be formed on site.
Combined boxes by Swarm serve as box access for rodding and as an outlet point to connect to the external drainage network. Preformed knockouts are indicated on the box for standard pipework sizes.


Is Swarm Aqua® a grating system?

Swarm Aqua® is a linear surface water drainage product. Where grated systems have removable gratings, once Swarm Aqua® is installed according to our installation instructions, it is designed never to be removed. The expected design life of Swarm Aqua® is >60 years.


What accessories do I need to use with a Swarm Aqua® system?

Swarm Aqua® is always quoted with everything you need for the system to be installed. End caps, transition pieces, chamber connectors and combined boxes are all that you may need, with no sealant or additional items necessary. It is also possible to use most standard twinwall pipe accessories (such as 90 degree bends) with minimal modification required.


Do I need to seal the joints on a Swarm Aqua® system?

Swarm Aqua® channels come with a factory fitted collar and interlocking male and female ends. It is not necessary to seal any of the joints on a Swarm Aqua® system as the concrete itself is designed to achieve the watertightness of the product. In some cases, it is necessary to tape over joints with construction tape in order to prevent ingress of concrete during the installation process.


What surface finishes can Swarm Aqua® be installed in?

Swarm Aqua® drainage channels can be installed in a range of surface finishes, though most typically concrete, asphalt and block paving. Please note that asphalt installations still require a concrete surround, however an asphalt wearing course is used past the iron top.


Is Swarm Aqua® chemical resistant?

As the main channel body or the Swarm Aqua® drainage system is manufactured from HDPE, it has a very good compatibility rating with most acids and bases. HDPE is resistant to most naturally occurring chemicals.


How do I clean and maintain a Swarm Aqua® channel?

A full O&M Manual is available online for download, however to maintain Swarm Aqua® channels, they can be either rodded from a combined box or jetted down through the slots.


How often do I need to use a combined box on a run of Swarm Aqua®?

Standard rodding equipment is usually up to 50m long. Usually a combined box as a rodding point is specified every 50m, or if there are multiple changes in sizes (i.e. a stepped fall system).


What grade of concrete is required to install Swarm Aqua®?

Our recommended concrete grade is 32/40. Installation details are available to download from the members section of our website.


What are the drainage capacities of Swarm Aqua®?

Here are the volumes of each of the Swarm Aqua® sizes:

150mm: 17.67l/m
225mm: 39.76l/m
300mm: 70.69l/m
375mm: 110.45l/m


In terms of the slot opening, twin drainage slots have been designed to intercept up to 15352mm2/m and this is standard across all products in the Swarm Aqua® range.

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