FAQ

Large Diameter Pipes

Can Ridgistorm-XL be recycled?
Ridgistorm-XL is manufactured from Polyethylene and is 100% recyclable at the end of its useful life.

What quality standards does Ridgistorm-XL meet?
Ridgistorm-XL is approved by WRc and is designed to meet the performance requirements of the European sewer pipe standard BS EN 13476. Ridgistorm-XL also meets the requirements of DIN16961. BBA approved for sizes 750mm and 900mm as a sealed system. Approved by most water companies for capital works and section 104 schemes.

Do Ridgistorm-XL pipes deform under loading?
Ridgistorm-XL pipes are designed to deform. The deflection of flexible pipes is controlled by the settlement of the soil. After settlement, traffic and other loads do not affect pipe deflection. With rigid materials such as concrete, traffic and other loads must be resisted by the pipe itself, making the pipe prone to cracking. However with flexible pipes such as Ridgistorm-XL the surrounding soil absorbs the stresses ensuring that the pipeline remains intact.

Pipe deformation

What happens to the Ridgistorm-XL joints when deformation occurs?
The joints within the Ridgistorm-XL pipe system are tested for leakage under deformation. This stringent test ensures that the joint remains water tight even when pipes are deformed by 5% and the socket by 10%, deformation far in excess of that encountered by the pipes in application.

Does Ridgistorm-XL have a proven track record?
The technology used to produce Ridgistorm-XL pipes and fittings is tried and trusted and has been in operation for 20 years. In fact, over 40 production lines are in operation worldwide including Germany, Italy and Australia.

What is the Co-efficient of friction for the Ridgistorm-XL pipes?
0.06. Ridgistorm-XL pipes benefit from a smooth inner wall, providing superior hydraulic performance when compared with rigid materials such as clay or concrete. See table below for details:

Wall roughness

Are Ridgistorm-XL pipes abrasion resistant?
Pipes manufactured from Polyethylene or Polypropylene offer far greater abrasion resistance than alternative materials. The following graph shows the abrasion curve of various pipe materials according to the results of the Darmstadt procedure. This graph demonstrates the superior performance of PE and PP pipes.

Abrasion resistance graph

Are Ridgistorm-XL pipes UV resistant?
Yes, Ridgistorm-XL pipes are resistant to UV attack and can be safely stored on-site without any damage or ageing effects for a maximum of 6 months. Ridgistorm-XL pipes may also be suitable for some above ground applications.

What is the standard bedding detail for Ridgistorm-XL pipes?
Type S bedding detail is standard for the installation of the Ridgistorm-XL system. However, by using the unique Easypipe software, we are able to engineer alternative trench bed and surround details to ensure optimum construction methods to suit each individual project.

Are Ridgistorm-XL pipes easy to handle and store on-site?
Yes, Ridgistorm-XL pipes can be handled by forklift without the need for any additional equipment on-site. Ridgistorm-XL pipes can be unloaded and transported to the trench by excavator which will already be present on-site.

How should Ridgistorm-XL pipes be stored?
When storing Ridgistorm-XL pipes and fittings it is necessary to ensure that they are stored on flat ground, free of stones or other sharp objects to avoid any point loading on the pipes. It is also important to rotate each pipe layer by 180 degrees so that the sockets of the upper layer are not lying directly over the sockets of the lower layer.

Do not stack Ridgistorm-XL pipes more than four metres high, it is also important to use wood bearing supports between the pipes to ensure even load distribution and wooden chocks.

Geocellular Solutions

What geocellular solutions do Polypipe offer and what are the differences?
Polypipe is the UK’s largest provider of geocellular systems. Our product range consists of Polystorm, providing a comprehensive choice of geocellular solutions for a wide variety of applications and surface loads, and Permavoid, for shallower excavations and restricted or contaminated sites.

Permavoid is part of a holistic system for water management and treatment, with a range of associated capture, filtration and pollution control products.

What applications can Polystorm be used for?
Attenuation – Cellular structures can be wrapped in a non-permeable geomembrane to receive rainwater collected from the roof gutter system or surface water drains. The stored water can be released within a set discharge rate through the use of a Stormcheck Vortex Flow Control chamber.

Soakaway – Where soil conditions allow, the structure can be wrapped in a permeable geotextile which can slowly release the water back into the surrounding soil.

What traffic loadings are Polystorm cells designed for?
The Polystorm range can be used for non-trafficked, trafficked or heavily trafficked applications:

  • Polystorm Lite is designed for use in landscaped, pedestrian or other applications where loads do not exceed 20 tonnes per square metre.
  • Polystorm is designed for use in lightly trafficked and loaded applications of up to 40 tonnes per square metre.
  • Polystorm-R is produced from carefully researched and selected recycled materials to provide an environmentally-friendly solution to surface water drainage and storage solutions applications. Polystorm-R has a 65 tonne per square metre compression strength and is ideal for lightly trafficked and pedestrian applications.
  • Polystorm Xtra is designed for use in deeper build depths and for heavily trafficked and heavy loaded applications of up to 80 tonnes per square metre.

What applications can the Permavoid system be used for?
Permavoid is designed specifically for use in shallower applications, where site conditions limit deeper excavations. It takes the place of a traditional aggregate sub-base and provides a strong, stable raft that can tolerate heavy traffic loadings despite its relatively shallow depth.

  • Brownfield sites. Where excavation beyond a certain depth risks disturbing contaminants left over from previous land use, Permavoid provides practical and flexible water management.
  • High Water Table. In certain areas, rainfall can easily raise ground water levels critically close to the surface. At just 150mm deep, Permavoid sits above the water table in all but the most exceptional ground conditions and climates.
  • Attenuation. Permavoid provides excellent shallow depth attenuation beneath paved surfaces. It can be linked to source control features such as Permafilter (itself a first stage filtration and pollution control measure) or accept water directly through permeable pavement blocks.
  • Infiltration. Where soil conditions allow, the Permavoid structure can be wrapped in a permeable geotextile which can slowly release the water back into the surrounding soil.
  • Treatment. Permavoid cells are part of a wider holistic system for water capture and treatment, featuring surface water channel drainage and silt capture systems (Permachannel), a semi-permeable pollution treatment membrane (Permafilter) and an in-cell hydrocarbon treatment mat (Permavoid Biomat).

How much water can a cell in the Polystorm and Permavoid range hold?
Polypipe’s cells have a 95% void ratio, providing greater water storage capacity and reduced excavation and disposal costs.

Can the different Polystorm cells within the range be use in conjunction with one another?
Yes, the Polystorm range of cells can be used in conjunction to create a cost-effective hybrid construction, depending on the load and burial depths for any given project. When integrated as a hybrid structure, a complete value engineered solution can be adopted for any given project. To reduce costs it is possible to construct a hybrid tank that contains all types of cells, with the stronger Polystorm cells at the bottom and Polystorm Lite crates at the top.

What is the design life of the Polystorm and Permavoid cells and can they be recycled?
Polystorm cells have a 50 year design life and are 100% recyclable at the end of their useful life.

What is the minimum cover and maximum burial depths for each Polystorm cell?
Based on ground conditions being dense sand and gravel with no ground water present the following applies:

  • Polystorm Lite
    Pedestrian applications - minimum cover depth of 0.5m and a maximum of 2.5m
  • Polystorm
    Pedestrian applications – minimum cover depth 0.5m and a maximum burial depth of 3.8m
    Light traffic applications – minimum cover depth 0.6 and a maximum of 3.7m
  • Polystorm-R
    Pedestrian applications – minimum cover depth 0.5m and a maximum burial depth of 3.9m
    Light traffic applications – minimum cover depth 0.6 and a maximum of 3.6m
  • Polystorm Xtra
    Pedestrian applications – minimum cover depth 0.3m and a maximum burial depth of 5.45m
    Light traffic applications – minimum cover depth 0.5m and a maximum burial depth of 5.3m
    Heavy traffic applications – minimum cover depth of 0.89m and a maximum burial depth of 4.8m

Minimum cover and maximum burial depths may vary depending on load and ground conditions. Please contact Polypipe’s water management solutions technical team for further information.

Water Treatment

What impact does pollution in surface water have on the environment?
Oil and fuel deposits on roads, car parks and forecourts can quickly find their way into watercourses, surface water, ponds and other natural drainage processes. This represents a significant risk to water quality while threatening plants, animals and wildlife habitats.

How do pollutants enter the watercourses?
Oil and petrol spills bind to silt and sediment found on car parks, and are then ‘washed’ by downpours into stormwater management systems. Spillages from day-to-day forecourt ‘drip’, point loading spillages and accidents also contribute to petrochemical water pollution.

What is the legislation on surface water treatment?
Developers are facing new regulations to integrate systems that intercept pollution as close to the source as possible to help raise the overall quality of surface water discharged into the environment. The EU Water Framework Directive, introduced in 2000, gives member states until 2015 to achieve a good chemical and ecological status for inland and costal waters. The aim is to reduce groundwater pollution, in particular by removing fuel, oil and other ‘priority hazardous’ substances and to protect wetlands and other aquatic ecosystems.

What stormwater treatment options are offered by Polypipe?
We can offer a number of options for treating surface water depending on the level of treatment that is required. Our water management solutions team will advise you on how best to configure your water treatment solution and help you create a bespoke system based on the unique hydrology and specifications of your project. The available solutions include:

  • Silt traps – the first line of defence to isolate heavier particles such as silt, grit and organic particles through a process of settlement.
  • Ridgitreat Pipe and Treatment Filter System – A semi-permeable membrane for use with perforated plastic piping that filters and biodegrades petrol and oil deposits.
  • Permafilter – A self cleaning geotextile mat for cellular attenuation that retains hydrocarbon deposits while allowing clean water through.
  • Permavoid Biomat – Designed for use within Permavoid cells, Permavoid Biomat features a floating pollution control material to trap and degrade oil through microbial digestion.
  • Permachannel Above Ground – A combined collection and pollution control system that stills run-off to separate oil and other pollutants.
  • Storm-X4 – A highly effective oil retention unit for treating run-off from roads, car parks and forecourts where pollution is most concentrated.

Rainwater Re-use

How are tank sizes calculated?
This BSI rainwater harvesting code of practice BS 8515 gives guidance on design, installation, testing and maintenance of systems for non-potable applications. For more information visit www.bsi-global.com. Free assessments in accordance with BS 8515 are available through the Polypipe water management solutions technical team on 01509 615 100.

It is essential to have details of the site location, roof area, proposed applications, number of appliances and number of people within the building.

What is the burial depth of a Rainstream tank?
Rainstream GRP tanks can be buried at a depth of 4m from the crown of the tank to ground level. Ridgistorm-XL tanks can potentially be buried deeper dependant on the stiffness class of the pipe used to construct the tank and the associated backfill/surround.

Where does the mains water back-up feed into?
For a gravity system mains water is fed directly into the header or break tank. For a pressurised system the mains back up is fed via an internal air break directly into the underground storage tank. Polypipe also supply the Advanced Control Unit for pressurized supply, where a rainwater control unit houses a 200L break tank, complete with AA air break and duty standby booster pumps which delivers water under pressure to the point of use. When using the ACU, mains water back up is fed directly to the unit. Details of all 3 systems are available upon request.

Can the system be connected to Syphonic Drainage?
Yes. The Rainstream system is ideal for this, as all roof water can be directed to one outlet which is connected to the Rainstream RWH system, reducing additional pipework and ground work costs. Polypipe Terrain, a division of Polypipe is able to supply a complete system for siphonic drainage and can advise on breaking the siphonic flow prior to the water entering the RWH storage tank. For more Commercial information please call Polypipe Terrain’s Technical Department on 01622 795 200 and for Residential information please call Polypipe Building Products on 01709 770 000.

How high can water be pumped from the tank?
In order to obtain the most efficient system, the maximum height recommended is 15m on the standard pump. Larger pumps can be supplied if necessary. Polypipe can supply pumps to accommodate a wide range of requirements and can help you the customer to choose the right pump for your particular application. For more Commercial information please call Polypipe Terrain’s Technical Department on 01622 795 200 and for Residential information please call Polypipe Building Products on 01709 770 000.

Is the water clean?
The main aim of any Rainstream Harvesting system is to produce non-potable water that is clean, clear and odourless. Three stages of filtration take place to ensure the water is clean and clear prior to it reaching any non-potable appliance.

How does the system get delivered to site?
The tank and leaf filter will be delivered to site ready for installation. The components will be packaged separately and it is essential that the contractor stores them in a dry, safe and secure area. It is also the contractor’s responsibility to ensure suitable lifting equipment is on-site to take delivery of the tank. To discuss delivery requirements: for Commercial information please call Polypipe Terrain’s Technical Department on 01622 795 200 and for Residential information please call Polypipe Building Products on 01709 770 000.

What maintenance is required?
Regular maintenance of a Rainwater Harvesting System is essential for system performance and lifespan. Any maintenance schedule should be site specific, however as a minimum the leaf filter should be visually inspected at least twice a year with at least one inspection taking place after the Autumn leaf fall. In addition Polypipe advise that a maintenance regime is put in place to ensure that internal filters and UV systems are maintained on a regular basis. The in-line filter should be isolated and cleaned 2-3 times per year and the UV system should be checked and the UV bulb changed at least once a year.

What if I have a problem?
Polypipe has its own team of engineers, who are on hand to respond quickly to any queries you may have concerning your Rainstream system. In the first instance please make contact with us on 01509 615 100 and our technical team may be able to address your query over the phone. Otherwise an engineer can be on site within 48 hours to assist you.

Fabrications

Does Polypipe offer a bespoke fabrications service?
Yes. We are in the unique position of being able to offer our customers bespoke fabrications from our highly skilled in-house fabrications team, who are fully trained by The Welders Institute.

What types of bespoke fabrications can Polypipe offer?
Fabrications are created from our Ridgistorm-XL large diameter pipe, which can be used to produce manholes, catchpits, bespoke junctions and bends to any angle. Our in-house fabrication facility allows us to work in partnership with our clients to provide bespoke, pre-fabricated solutions to reduce both installation time and cost on-site.

What are the benefits of Polypipe’s plastic pre-fabricated manholes and catchpits?
The benefits of a plastic pre-fabricated solution include:

  • Straightforward one-piece installation
  • Strength and durability
  • Bespoke, fully welded and watertight construction
  • Off-site construction - delivered ready to install resulting in reduced installation time and costs
  • Robust, low weight construction, minimising health and safety risks while reducing installation time and costs
  • Depths can be tailored to suit project requirements
  • Fully bespoke option of inlets and outlets
  • Designed to integrate with the extensive range of systems from Polypipe Civils

What sizes are available?
Diameters 1050mm, 1200mm, 1500mm, 1800mm, 2100mm, 2400mm, 2700mm, 3000mm are available.

Are Polypipe manholes made to adoptable standards?
Yes, our surface water and sewer manholes are manufactured to adoptable standards.

What inlets and outlets can I specify?
We can design fully bespoke options, supplied with spigots as standard, to meet site-specific requirements.

Do I need to install a manhole or catchpit in a surround?
For pedestrian or light field loading, a granular surround will be suitable. For carriageways or locations subject to trafficking a concrete surround should be used.

Are step-irons and ladders available?
We offer double step irons to BS 1247 (now replaced by BS EN 13101) as standard, with orientations set to requirements. Ladders are also available.

Engineered and Soft SUDS

I need to store and improve the quality of water from site – what are the respective advantages of Engineered and Soft SUDS?
SUDS systems do not need to be exclusively engineered nor all natural solutions. In fact, a typical SUDS train will combine both ‘engineered’ and ‘soft’ SUDS features. For example, placing our Storm-X4 filtration before the outflow into a pond will clean the water to encourage bio-diversity.

Another significant effect of combining engineered and soft SUDS is that it can reduce the size of ponds and swales in a development by storing more water underground. This means more land can be used for buildings or public amenities.

What components make up a SUDS Train?
The SUDS Management Train, or SUDS Train for short, is a model to guide the design of effective surface water drainage.

It starts with measures to prevent run-off using sufficient unpaved or permeable paved surfaces to encourage infiltration. Next, it specifies local source control systems such as Ridgistorm-XL and modular cell tanks, followed by site control using planted areas to promote evapotranspiration.

Only then should water be conveyed off-site, via pipeaway structures, to be handled as part of the regional control process through discharge into rivers or wetlands.

How can I meet my flood storage requirements without using too much land space?
A combination of different solutions, both for above and below ground applications, can help provide adequate water storage while freeing up useable land for other amenities such as car parks, playgrounds, landscaped areas.

The Code for Sustainable Homes says run-off from my site shouldn’t exceed pre-development rates, even in a 1 in 100 year event. I don’t have the space for storage of that volume, so what should I do?
There are a number of ways to spread water around a site, including swales, ponds, rainwater harvesting and localised attenuation. Talking to us at the earliest possible stage in the planning process will ensure these features are combined in the most effective SUDS solution for your project.

What treatment measures are required before water can be released into the environment?
Before surface water can be allowed to flow back into ponds and rivers, it must be treated and cleaned in accordance with regulations such as the EU Water Framework Directive and the Groundwater Regulations.

We offer a range of products and technical design services for water treatment based on a concept of progressive separation, filtration and biological breakdown of petrochemicals and other pollutants.