For sewage pipelines a variety of manholes and special constructions for inspection, regulation and combination are necessary. Therefore, we have in our delivery programme for profile pipes manholes and special constructions with different functions, made of polyethylene and polypropylene. By using these materials, there is the possibility to have a nonstop welding of the sewer system - from the start to finish. Different material properties like reaction on subsidence will be considered for the complete system.
Usually PKS manholes consist of a bottom part made of polyethylene or polypropylene and will be completed by prefabricated concrete parts acc. to DIN 4034. In this case the ferro-concrete manhole rings carry off the traffic load directyl to the manhole wall. The bottom part which contacts the sewer or ground water is made of a noncorrosive polyethylene or polypropylene. Depending on load the manhole can also be manufactured completely in PE 80, PE 100 or PPR. The manholes will be furnished with a step in and step irons. PKS manholes themselves have an electro fusion socket and spigot end for a direct connection to the PKS pipes. The manhole is designed according to the corresponding requirement. PKS manholes distinguish themselves by a clear, inspection friendly inner surface, low weight and a very low roughness. In case of manholes with high traffic load, the manhole should have to the top with a plate of ferro-concrete to spread the traffic load. This plate carries the traffic load in the underground, so that no axial load can act on the manhole.
For sewer pipelines DN 300 up to DN 800 inspection manholes are used. Here you have the complete cross section of the sewer pipe within the entrance manhole. The entrance manhole is in this case: DN 1000 for PKS pipes DN 300 up to DN 500, DN 1200 for PKS pipes DN 600 and DN 1500 for PKS pipes up to DN 800. The channel of the inspection manhole is fabricated with a lifted, sure footed berm and sloped to the bottom. The upper part has conrecte manhole rings. Through this an individual adaption to the later terrain is possible. The height of the inspection manhole depends on the maximum ground water level. Generally, the passage from the PKS manhole to the concrete manhole rings should be higher than the ground water level.
For bigger sewer pipelines from DN 600 the tangential manole is used. Here the sewer pipe is outside the centerline of the entrance manhole and under the manhole bottom. Therefore, it is possible to design the entrance manhole as standard in DN 1000. As upper part of the manhole a ferro-concrete cover plate has to be installed to take off the load. The passage to the concrete cover plate should also be higher than the maximum ground water level.