Water master jochen roll from the municipal utility delivered what he promised on the trip to the main meadows near weyer. The appointment was very interesting and had to be postponed twice because the specialists from the company W. Markgraf gmbh&co KG from bayreuth (active throughout europe, just under 1000 employees) are damn fast.
Heavyweights in action
Two heavyweights are in action. The 30-ton tractor carries a cable winch with an arm-thick traction cable and becomes a "tank" called. The "plow weighs 25 tons and holds with the help of the "sword a "torpedo" up to three meters below the ground. Together they plowed in the up to 40-centimeter-thick steel pipes of the 26-kilometer-long water pipeline from the waterworks at the entrance to the schweinfurt weirs to wohnau at a speed of up to four meters per minute. That there are devices like the tank and the plow "in these dimensions" until the contract was awarded, water master roll had not known that the welded steel pipes would bend with increasing length, so that the most nature-friendly laying technique could be used for the rough project. Roll: "simply fascinating.
The tank rams its sign, a three square meter steel plate, into the ground in front of it. The shield provides the necessary counterpressure and keeps the tracked vehicle in place. Its winch then develops a tractive force of up to 160 tons, which is used to pull the torpedo through the subsoil at a depth of two to three meters by means of the hook of the hauling rope. Attached to this is a several hundred meter long section of the future water pipeline. However, the steel pipe may be subjected to a tension of no more than 85 tons (in the case of plastic pipes, no more than 25 tons). If higher forces act there, the permanent measurement on the pipe switches off the winds.
200 meters in two hours
At weyer, the excavated topsoil is mainly sand, which does not make the work any easier, because the sand immediately trickles down and acts as a brake like sandpaper. Clay soil is ideal, say markgraf's employees. In the clay, the torpedo, which has a diameter of 40 centimeters for the pipes laid here, itself has a diameter of 50 centimeters, presses a stable tunnel into the earth. The plow, whose wheels can be steered and extended individually, which is why the ride is reminiscent of a spider, supports the torpedo by ten to 15 tons of thrust through the power of the wheels.
Practice has shown that a plow and a tank can cover a distance of 200 meters in two hours. However, since one is not immune to surprises in the underground, four hours are assumed for planning the operation. For traditional pipe-laying with excavator and spade in a meadow, jochen roll sets a time frame of one week. However, the coarse-grained work does not save time and money everywhere. Tanks and plows must be suitable for rock and tighter curves at the latest.
The steel pipes are designed for a permanent water pressure of 25 bar. The washout on the inside with a special cement mortar as corrosion protection has alkaline properties and thus prevents bacterial infestation.
Ultimately, the pipeline must be handed over 100 percent germ-free after construction, which requires the utmost care in all work steps. The pipes are always closed with lids so that no mice or other animals can get stuck in the pipes. Also the line is spooled before the handover. Already after laying, when the tank and plow have been removed, the worked section is rolled before the topsoil is applied again.
The water pipeline is the result of intermunicipal cooperation between the schweinfurt municipal utility, the rhon-maintal group water supply association, stadtwerk habfurt gmbh and the knetzgau-sand-wonfurt water supply association. Schweinfurt's municipal utilities want to supply up to one million cubic meters of drinking water a year to their partners. This quantity corresponds to the decline in water consumption in the previous supply area over the past decades.