PROJECT REPORT NO. 2/2017 Pioneering sewage system of polyethylene (PE) in the “Am Hitzenhof” development area, Buchenbach www.friafit.com FOR HIGH LOADS FOR 100 YEARS OF SERVICE In Buchenbach near Freiburg, special drainage solutions were required for the new sewers in the “Am Hitzenhof” development area. THE INITIAL SITUATION operation, and their maintenance must The instructions in the Technical Rule On an inspection tour, District Admin- fulfil, providing important information DWA-A 142 were specified for practi- istrator Manfred Wagner of Breis- for the planning and construction cal implementation as early as 2005. gau-Hochschwarzwald explained the work. A number of district administration special conditions: “The Am Hitzen- bodies in Baden-Württemberg drew dorf development area is only about a This information often directs atten- up the guideline “Waste water lines in thousand metres away from the cen- tion to potential problems, yet pro- water conservation areas – Principles, tral drinking water well of Himmelre- vides enough leeway for the design, requirements, information for domes- ich-Verband Buchenbach, Falkensteig necessitating a high degree of situ- tic waste water in Baden-Württem- und Burg, in a Zone IIIa Water Conser- ational risk assessment during the berg”. The object was to define and vation Area (WCA).” (Fig 1) planning phase. support the practical implementation of these measures. In other words, public sewers and pri- This can fuel lively discussions among vate waste water pipes must be tight. experts as to whether e.g. industrial THE CHOICE OF SYSTEM Neither outside water may enter these waste water should be rated higher In the runup to the plans for the Am pipes, nor waste escape into ground- than domestic. Hitzenhof construction project, it was water. primarily soil analyses that revealed In practice, for instance, industri- the high hazard potential posed by THE LEGAL SITUATION al waste water flows at a defined, sewer operations. The whole is regulated in the German constant rate, and so can be handled According to the estimates, discharg- Federal Water Act (WHG). Guidelines often with relative ease. Generally un- ing waste water could easily enter and for the practical implementation are to disputed, however, is the considerable pollute the groundwater through the be provided by DIN, DWA, and DVGW hazard potential posed to ground- permeable soil strata. technical rules. For these applications, water by waste with high microbial the Technical Rule DWA-A 142 (sew- concentrations. age lines and sewers in water catch- ment areas) regulates the additional requirements that new systems, their Fig 1 – Overview of water conservation areas (not to scale) 02 Analyses of groundwater levels over sure of up to 10 bar. other to form a homogeneous unit. a period of months confirmed these Seals, the crucial weakpoint on plug-in estimates and provided limits for Also the PE shaft sections, usually connections, then become superflu- the development plan. Now detailed assembled with plug-in connections, ous. The connecting area is level with specifications could be elaborated for were fused to a tight monolithic shaft the passage for the optimally smooth basements and underground garages. structure before leaving the plant. hydraulic surface, without coupler gaps The main task, however, was to define and without beads. Obstructions and the requirements for the waste water This system is flexible and can take malfunctions in the sewer are eliminat- drainage system. high loads. Besides its environmental ed from the outset. safety, also its long service life makes A number of variants were drawn up this economically appealing. Domestic drainage connections are and discussed with the involved insti- realised with sewage saddle fittings. tutions, the district administration, the According to DIN 8074 “Polyethylene These are installed with the specially Kirchzarten utility ewk, and the inter- (PE) pipes”, the predicted service life of developed clamping and tapping unit communal association for waste water fused lines is a verified hundred years. FWFIT. Here, the sewage saddle treatment AZV Breisgauer Bucht. Also ASA TL is first clamped on the pipe the future inspection and maintenance THE FUSION PROCEDURE and then fused homogeneously to the intervals had to be observed on the Electrofusion (EF) generates a homo- main sewer. Afterwards, access to the planned drainage system. In the end, geneous material bond between the pipe is cut out (Fig 3a). the decision went to a single walled, pipe and the fitting (Figs 2a and 2b). continuously fused pipe shaft system The temperature of about 210 °C need- of polyethylene (PE) extending into the ed for fusion is provided by heating new buildings. On the one hand, these wires, so called heating coils, across two tone, coextruded PE pipes exhibit which a defined voltage as high as a light coloured internal surface ideal 48 V is applied depending on the thick- for TV inspections, and on the other ness of the pipe wall. The two parts for they can withstand a high water pres- joining (pipe and fitting) melt into each Fig 2a – Direct heat transfer from Fig 2b – Completed pipe connection exposed heating coil 03 The pipe cutout is held firmly and removed since the mid 1970s, and today PE has become the together with the device (Fig 3b). The result is a standard pipe material. level passage outlet, smooth on the inside for un- obstructed flow, as shown in the section through In the waste water field, the FRIAFIT sewage the assembly (Fig 4). system could prove its practicability as early as 1994. At that time, the main sewers and about 300 Now the domestic service pipe is connected to domestic sewer service pipes of PE were installed the sewage saddle ASA TL. Available for this are in a Göttingen development area. About 2000 special sewage bends ABM (coupler–coupler) and components of the FRIAFIT sewage system have ABMS (coupler–pipe spigot), each with 15°, 30°, been installed in total. The following decades saw and 45° (Fig 5). many other projects nationwide, and the fittings range was expanded successively. TO SUM UP The development project was concluded in Sep- What lends the Buchenbach development a tember 2016. On a tour of the site with all involved unique feature, however, is the consistency with in the project, Mayor Harald Reinhard praised which the advantages of a homogeneously fused the good work by all. Virtually the entire Dreisam PE waste water system could be extended into the valley has been designated a water conservation buildings. area, so Buchenbach served as a pilot project. Further measures with analogous implementa- Hence the state of the art now safeguards the tions are in the planning stages. maximum possible environmental safety for future generations as well. Although appearing novel and innovative at first glance, this procedure is actually quite long in the tooth. PE piping has been used in domestic ser- vice installations for over sixty years. Gas distribu- tion systems have been benefiting from PE piping Fig 3a – Tapping with the FWFIT Fig 3b – Pipe cutout being removed Fig 4 – Section through a sewage Fig 5 – Connection with sewage saddle ASA TL saddle model ASA TL with connections and bend ABMS between saddle and pipe section and between outlet and domestic service pipe 04 Details on the project Measure Am Hitzenhof development area Building site Buchenbach, Black Forest Main contractor Johann Joos Tief- u. Straßenbauunternehmung GmbH & Co. KG Installed by Tecoba GmbH Technik Consult Baden, Endingen am Kaiserstuhl Planner F. S. Ingenieure GmbH, Ettlingen AM couplers SDR 17, ASA TL sewage saddle top-loading, ABMS sewage FRIAFIT fittings bends (coupler / pipe spigot) FRIATOOLS Technical equipment FRIAMAT universal fusion unit, FWFIT clamping and tapping unit The wide, sun filled Dreisam valley is framed in an The new development Am Hitzenhof will be built impressive mountain setting. Buchenbach is one with a view of the Kreuzberg Chapel, encouraging of the three Dreisam communities, with its Him- young families to remain in their home surround- melreich and Falkensteig districts extending over ings instead of moving away. the famous lower section of Hell’s Valley. FRIATEC Aktiengesellschaft Technical Plastics Division Steinzeugstraße 50 – 68229 Mannheim, Germany Tel.: +49 621 486 2238 info-friafi[email protected] www.friafit.com Update: 1/2018 Update:.