The NORIS-Project and the Top-Cote-Liner

The NORIS project

The NORIS project started in February 2004 and copes with key subjects

• Technological innovation and feasibility
• Measuring of environmental impact
• Sustainability
• Transnational exchange
• Communication and dissemination.

Stormwater runoff and rainwater entering the sewer system can cause problems such as flooding, surface water pollution and disturbance of the hydrological cycle at a local or broader level. The main purpose of the NORIS-project is to improve water quality and to reduce other quality and quantity-related problems by preventing excess water from entering sewers. This will improve water quality by reducing sewer overflows, and enable wastewater treatment plants to work more efficiently.

NORIS introduces modern technologies such as innovative no-dig techniques, two-in-one sewer relining and stormwater filtration technique in the area of rainwater disconnection. One aim of the project is to produce an Inspiration book for spatial planners which will explain how to apply the innovative no-dig technology and source-control measures used within NORIS.

A Guidebook will also be produced. This will describe how sustainability assessment techniques can be utilised and also how they should be applied to projects involving separation or disconnection of rainwater and runoff. There will also be a lot of communication via workshops, study visits and regional conferences. Relevant stakeholders will be directly and indirectly involved in the project.

Five different kinds of pilot projects will give the opportunity to demonstrate the potential and the practical use of new technology to solve stormwater/drainwater-related problems. Some of the projects will study how to return rainwater to groundwater, thus restoring a more natural local hydrological regime.

The NORIS partnership has been put into place for the tasks. The partners complement each other since they all are representatives for different and specialized knowledge. Each partner has its own task, making the project a common unity and a forum for exchange of knowledge. Hereby the project is strengthened and opened up for true interregional co-operation.

The partners in the NORIS are from:

• Sweden - The Municipality of Skövde and Chalmers University of Technology
• Germany - The City of Hanover
• The Netherlands - Waterboard HHNK
• Belgium - The Municipality of Ieper
• UK - Bradford City and Sheffield University

Following companies have special responsibility in NORIS:

• Tyréns AB, Sweden (consultant and designer of the pilot of Tidan)
• Rencon AB, Sweden (contractor for the Top-Cote liner)
• Gebr. Röders AG, Germany (manufacturer of the Top-Cote liner)
• IPS, Germany (consultant and designer of the Innolet and the Innodrain)
• TNO, The Netherlands (consultant for measurements)

The Pilot of Tidan

  Tidan is a village with about 2000 inhabitants, situated twenty kilometres from Skövde. Flooding due to an overloaded sewage system has been a problem for several years in Tidan.
According to an environmental report from the area, flooding occurs about 7-10 times a year and the amount of sewage that comes to the treatment plant is approximately 30 % hig her than the amount of water going out from the fresh water plant. The sanitary sewage system in the area is a separated system, which means that the system is not dimensioned to contain drain and rain water.

Therefore the purpose of the pilot project in Tidan, Skövde, is to decrease flooding and obtain a better water quality in the area. This will be achieved by disconnecting drainage from the sewage system using new technical solutions.

In addition to the benefits from disconnecting drainage, the rehabilitation will prevent leaking pipes and groundwater pollution. There should be no overflows of sewerage to the river Tidan and no flooding to cellars in the village. It will also decrease the costs for pumping and chemical usage in the sewage treatment works.

The planning of the pilot project started with a preliminary study and has continued with:

• TV-inspection of sewers in streets and laterals on private properties
• Smoke tests to investigate defect couplings
• Geotechnical investigations to survey areas with possibility for infiltration
• Groundwater examinations to investigate water level changes over time
• Rain gauging and flow monitoring for the analysis of the hydraulic system.

The work has also included spreading of information to property owners, shopkeepers and local associations.

The plan for Tidan is to reconnect the disconnected rainwater to the surface water system and separate the drainage from the sewerage to a new drain system. This drainage should be integrated in a separate canal/pipe in the sewer and the drain water should be discharged to an infiltration system around the manholes or pumped to the surface water system. The sewage treatment works will receive the remaining sewage.

To transform the ideas of a completely new sewer system into reality, a lot of work has been put into the design of connections in manholes and wells. Some new pipes have been installed with traditional digging technique and with horizontal directional boring technique. But with the new pipe technology (Top-Cote liner) there is a possibility to do the reconnection in an easier way.

In total, more than 1.500 meter sewers in dimension 225 and 300 mm will be rehabilitated with the TopCote system. Nearly 30 laterals in dimension 150 mm will be completed with the two in one system this autumn. The pipes are located in both public and private areas.

The laterals in the private areas have been rehabilitated mostly with a bottom positioned pipe and the public sewers have been rehabilitated with a top positioned pipe. In laterals, the circular pipe in the bottom is for sewerage/waste water. The reason for the bottom position in laterals is to keep the water level as low as possible both on the drainage and the waste water.

In the public sewers, the circular pipe in the top is for drainage which makes the connection in manholes not so complicated. This solution was also chosen because of the flat landscape with little difference in water levels.

Top-Cote Liner and Technological Innovations

There is a large potential to reduce social costs by using no-dig technology. No-dig techniques have minimal influence on social costs as disruption and delay to commercial and private traffic, traffic accidents, loss of public and private amenity, and environmental impacts such as noise, vibration, air pollution and visual pollution.

NORIS includes no-dig technologies that reduce disturbance in sensitive areas; the research and development of the TopCote-system (the 2-in-1 relining technique), investigations into the feasibility and effectiveness of Innolet (filter system for rainwater treatment), along with the feasibility of Innodrain for stormwater management (see figures below). Each of these may be applicable in a range of locations in the pilot projects.

The TopCote method enables excavation free separation of combined sewers in urban environment. This is possible by using an existing well-known and tested technique used to renovate leaking pipes. The pipes are relined with a flexible tube, which is cured-in-placed on the inside of the host pipe. The second pipe is integrated in this tube and cured-in-placed during the same process.

Leaking pipes and polluted groundwater create inconveniences in many cities, especially in older sections. The two-in-one liner technique renovates and reinforces pipes at the same time as the separation is carried out. Flow capacity will be maintained or increased due to lower friction of the new improved inside coating of the pipe. Minimal impact on traffic and environment reduce re-routing and restoration of streets.

One main objective of the NORIS pilot project is to increase the knowledge of the new TopCote-system. Knowledge and experience is required to make it a sustainable solution to this widespread problem.

The new technique with a two pipe in one system, is built up on a traditional CIPP-liner construction. The cured in placed pipe are named Top-Cote liner and it is designed with 2 pipes instead of the normal one. The extra pipe can be put in the top or in the bottom of the pipe and be used for a lot of different things such as:

• Drainage
• Filtration system
• Pressure Pipe Installation
• Cable installation
• Fluid separation, etc.

The Top-Cote liner is produced with woven polyester felts with special designed layers. The felts are sewed together and manufactured with coatings on the layers. The felt is impregnated with epoxy or polyester in the factory and then packed in a cooling container and transported to the jobsite.

The installation of the liner can only be done by pulling it in by a winch because of the demands of getting it positioned at a constant circumferential location at 6 or 12 o'clock. The liner is set up with air pressure or water pressure and cured with steam or hot water in both pipes.

The design and trials have so far focused on:

• The different combination of dimensions which should be used in the liner
• The position of the extra pipe, in the top or in the bottom of the liner?
• Material and thickness of the wall in the liner

 

Combination of dimensions

Since the dimension should correspond as close as possible to existing standard diameters for pipes it has become necessary to find out some useful dimensions. The decision will depend on what kind of water/fluid that will flow in the liner.

In Tidan there has been a discussion if the waste water should flow in the small and circular pipe or in the large and non-circular pipe. The result depends on the location of the small new pipe in the top or in the bottom of the old pipe. It will obviously also depends of details in the local object as the existing water level, the gradient of the sewer, the locations of connections and so on.

However, the decision has been that the small and nearly circular pipe always must be tight and fit together with standard dimensions and couplings. To do this, there must be forms installed in every end of the liner. The form is made of a non plastic material and placed in position before the hardening of the liner takes place.

The proportion between the pipe-canales depends on the original pipe dimension. It must always be possible to use CCTV-inspection and cleaning equipment in the smallest dimension. Cutter equipment can normally only be used in pipes with large diameters.

A proportion of 1 to 3 can be a good start for a design but it depends on the demands and the proposal from the project engineer. The installation tests give one answer. A larger circular pipe/canal can be designed in the bottom rather than in the top because of the gravity.

So far the dimensions are 50 in 150 mm, 75 and 100 in 225 mm and 110 in 300 mm. Next step will be 125 and 160 in 400 mm, 160 in 450 mm and 200 in 600 mm.

Design and calculation of dimensions due to required flow capacity would be done for each of the pipes in the traditional way. When the capacity is reached for the rainwater pipe a redirection to groundwater via a percolation- and treatment system, will take place.

Top or bottom?

Depending on the position of the extra pipe there will be advantages or disadvantages to the system. If the extra pipe will be placed in the bottom there will be:

• Easier connections to laterals in the upper pipe
• Difficulties to connect laterals to the lower pipe (Settled deposits will appear in the non-circular pipe because of connections to the lower pipe)
• Difficulties for inspection with CCTV-cameras in the non-circular upper pipe
• Extra good hydraulic self-cleaning in the double egg shaped bottom of the upper pipe
• Good assurance of getting an exact position of the bottom pipe.

If the extra pipe will be placed in the top there will be more advantage to the system like:

• Easy connections to laterals in both the upper and lower pipe
• Easier inspection with CCTV-cameras in both the circular and non-circular pipe (see above)
• Good hydraulic condition in both pipes
• Lower assurance of getting an exact position of the upper pipe.

A problem with the TopCote system is how to make tight and good connections to laterals and other pipes. So far the only solution for connecting laterals to the system is by install a manhole in every connecting point. From special designed manholes the connections have been handmade with laminating and standard fittings.

In the future there hopefully will be special designed fittings for the system and perhaps cutters for making special connections to laterals.

Material and thickness

A contractor making this type of liner must have a very good experience and knowledge of normal CIPP-installations. The product manufacturer guidelines for installation procedures must be followed very carefully. For the Top-Cote liner the issue becomes not only critical for curing time and temperatures but also for the co-ordination of pressures in the 2 pipes.

Since there are two liners in one which are hardened at the same time there must be two separated systems from the boiler truck. There are very strict demands on levels of the pressure which must correspond to the pressure in the opposite pipe. The whole liner must also have a constant pressure against the wall of the old pipe, so that the resin will create a nearly constant wall thickness of the whole circumference.

Mixing of resin and impregnation of the liner is an industrial technique which must follow a certificated production. Both Polyester resins (UP) and Epoxy resins (EP) have been used with good results. The resin must have a temperature interacting with a high viscosity so the double felt will get saturated.

The special needled felt liner must have internal and external coatings. The needlework must be undertaken with a high control to get small tolerances on every part of the wall thickness in the two pipes. Fibre glass can be used as reinforcement to get higher ring stiffness and tensile strength on the liner. But there is still a lot of calculation on stiffness left to be made for optimization of wall thickness.

Conclusion

The TopCote liner has been tested in the Noris project with good result. The development of this two in one technique will continue with several kilometres in Noris pilot projects. When there is some special designed manholes and fittings on the market the system will be complete.

Typical failures or defects for a Cured-In-Place liner are bulging, fold-and-formed shrinkage, and ribs on liners. The test of TopCote liner has not showed more of this than any other traditional liner system.

Especially the bends, can restrain the pulling of an impregnated liner. Since this liner is heavier than a traditional one, it is more important of having a good external coating on the liner to prevent friction. Curvature of a sewer will also give some risk for that the upper pipe will change a little bit in circumferential location.

The small and circular pipe should always be designed as if it was a low pressure pipe system. Then there will be a possibility for using standard couplings and fittings on the system. The non-circular system can be designed as a traditional rehabilitation where it could be possible to use CCTV-cameras, cleaning equipment and even cutters in large dimensions.

The small and circular pipe in TopCote can probably also be used for relining of pressure pipes, cable installations and fluid separation.