In June 2008 the Japanese SEKISUI Chemical Group acquired a majority shareholding in SEKISUI SPR Europe GmbH (formerly CPT Chevalier Pipe Technologies) with headquarters at Schieder-Schwalenberg in Germany. From this time onwards SEKISUI Europe has been pressing ahead with the global marketing of underground infrastructure solutions as a part of the SEKISUI urban infrastructure and environmental products company – with a workforce of more than 500. Backed by a financially sound majority shareholder, SEKISUI Europe can fall back on a wide range of leading technologies. The spiral-wound pipe lining method by Australian subsidiary SEKISUI Rib Loc, the pipe lining process of SEKISUI NordiTube and the Japanese SPR technology that enables the rehabilitation of a wide range of large-profile shapes all contribute to achieving the goal of global market leadership, said the company. A further system invented in Japan, marketed through the SEKISUI Europe network and by KMG Pipe Technologies GmbH in Europe since 2008, is the SIVAC vacuum sewer system – a technology for sewer pipes.

Economical alternative

The SIVAC vacuum sewer system has been successfully in use in Japan and other parts of Asia for the past 15 years and is now being marketed worldwide. Disposal of municipal wastewater via a vacuum system is particularly suitable for sensitive environments such as lakes, coastal areas or harbours. This is because the pipe system can be laid with a shallow gradient in very narrow trenches, as only small diameters of 80–200 mm are required. The special configuration of the vacuum pipes in a ‘saw-tooth principle’ even enables the delivery of wastewater along upward gradients. Bodies of water or intersecting pipelines, for example, are no longer a problem and construction costs are substantially reduced. Furthermore, shallow installation means that no new resources such as sand are required as a filling material. In comparison to a conventional gravity flow system the SIVAC vacuum sewer system produces savings of up to 40 per cent in installation and operational costs and protects the environment at the same time. In narrow pipes to the sewage treatment plant

As shown in the diagram, the SIVAC vacuum sewer system consists of a domestic connecting shaft that first of all collects the sewage effluent in tanks. Three-inch valves permit sewage from up to six households to run together. A controller opens the vacuum valve of the collection tank to enable the wastewater to be suctioned into the pipe system and on to a vacuum station by vacuum. Here it is collected in a vacuum tank until pressure pumps deliver the sewage to the municipal sewage system when it reaches its capacity.

Leak-free and self-cleaning

A vacuum sewer system has an enclosed system design with all pipes hermetically sealed similar to a potable water or gas pipe system. This precludes the possibility of either infiltration of groundwater or exfiltration of wastewater into the surrounding area. It guarantees complete freedom from leakage and relieves the burden on municipal sewage treatment plants. Furthermore, system-inherent self-cleaning effects render the normally required annual pipe cleaning unnecessary (in Germany, for example, every water pipe system must be cleaned twice a year). Installation by the ‘saw-tooth principle’ enables all suspended solids and deposits to be carried away by the turbulence resulting from suction, so that the pipe is kept permanently clean. Vacuum sewer systems are thus particularly eco-friendly and keep the burden and hazards to the environment to a minimum. In contrast to other vacuum sewer systems, SIVAC technology incorporates line aeration valves that automatically ventilate the system, enabling wastewater to be transported over distances exceeding two kilometres, said the company.

Numerous applications

Shallow installation and small pipe diameter mean that the potential applications of the SIVAC vacuum sewer system are almost limitless. It is suitable for draining recreational and industrial areas, low-lying urban neighbourhoods and areas with a high groundwater table, for crossing pipelines, roads and rivers or areas with difficult soil conditions. SEKISUI Europe is thus pursuing ambitious goals with its in-house SIVAC system: several projects in major international cities are already on the drawing board and are due to be executed in 2010 by construction companies within the group. One of them is the long-established German KMG Pipe Technologies that uses the Japanese SIVAC technology in Europe and can draw on the expertise of a global network of specialists for underground infrastructure at SEKISUI Europe.