FRAUNHOFER-INSTITUT FÜR GRENZFLÄCHEN- UND BIOVERFAHRENSTECHNIK IGB Guideline: Vacuum sewer systems Guideline: Vacuum sewer systems December 2016 Dr.-Ing. Marius Mohr, Jan Iden, Marc Beckett Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB Nobelstraße 12 70569 Stuttgart Content 1 Introduction ........................................................................................................... 1 2 Technology of vacuum sewer systems ................................................................ 4 2.1 Concept ................................................................................................................... 4 2.2 Components and their tasks..................................................................................... 5 2.3. Manufacturers / System providers .......................................................................... 21 3. Investment costs ................................................................................................. 25 4. Operation and Maintenance costs ..................................................................... 29 4.1. Electricity costs ....................................................................................................... 30 4.2. Personnel cost ........................................................................................................ 31 4.3. Material cost .......................................................................................................... 33 4.4. Other costs ............................................................................................................ 34 5. Durability (life span/life cycle) ........................................................................... 35 6. Operational and maintenance skills required .................................................. 38 6.1. Normal and preventive maintenance ...................................................................... 38 6.2. Emergency maintenance ........................................................................................ 41 6.3. Record keeping ...................................................................................................... 42 6.4. O&M manual ......................................................................................................... 44 6.5. Spare parts ............................................................................................................. 45 6.6. Summary................................................................................................................ 45 7. User friendliness .................................................................................................. 46 8. Cases for application ........................................................................................... 49 9. Reference projects ............................................................................................... 50 10 Vacuum sewers as part of an integrated water management concept ......... 54 11. Critical issues for building and operating a vacuum sewer system ............... 61 11.1. Pros and Cons ........................................................................................................ 61 11.2. Critical features ...................................................................................................... 62 11.2.1. General .................................................................................................................. 62 11.2.2. Collection pits ........................................................................................................ 63 11.2.3. Interface valve ........................................................................................................ 64 11.2.4. Vacuum lines / network .......................................................................................... 64 11.2.5. Vacuum station ...................................................................................................... 65 12. Summary & conclusion ....................................................................................... 67 References ........................................................................................................................... 69 Annex 1: ............................................................................................................................ 73 Annex 2: ............................................................................................................................ 76 Annex 3: ............................................................................................................................ 78 Annex 4: ............................................................................................................................ 79 Fraunhofer IGB Vacuum sewer system GIZ GmbH I | IV List of Figures Figure 1: Overview of a vacuum sewer system involving the vacuum valve unit at the valve pits, vacuum mains and the central vacuum station [8] 5 Figure 2: Left: Schematic layout of a collection pit with vacuum valve ; Right: prefabricated collection pit . 6 Figure 3: Vacuum valve [12] 8 Figure 4: Valve pit with two interface valves to accommodate higher discharges [5]. 9 Figure 5:Hierachy of pipes within a vacuum sewer system and the corresponding pipe diameters [5]. 10 Figure 6: Saw-tooth profile of a vacuum sewer line [5] 11 Figure 7: Filling material of excavation for a vacuum line. Trenching material in the top layer, followed by a layer of gravel and a liner which separates the gravel from the sand [7] 13 Figure 8: Division valve with gauge tap at a vacuum main [5] 13 Figure 9: Service lateral connection [1]. Note that the diameter of der service lateral is equal to the diameter of the interface valve (= 3 inch = 7.6 cm). Pipes should be joined at the upper part of the receiving pipe at an angle of 60° 15 Figure 10: The vacuum station can be designed with high flexibility. Anything from prefabricated houses to underground stations which are integrated into the environment exists [12]. 16 Figure 11: All vacuum pumps are connected to the same pipe. The pumps are setup in parallel. 17 Figure 12: Layout of a vacuum station with the collection tank in the ground and the sewage pumps outside of the tank. The vacuum reservoir tank is integrated into the collection tank in most layouts[5, 14] 18 Figure 13: Biofilter used for odour control from a vacuum tank. Right: woodchips are a common filling material [1] 19 Figure 14:Vacuum station with external power connection for power supply in case of blackouts [12] 20 Figure 15: Comparison of elements most susceptible to failure in different sewer systems; diagram based on [26] 47 Figure 16: Reconditioning time for different sewer systems [26] 48 Figure 17: Number of vacuum sewer projects implemented by ROEDIGER and AIRVAC (now Aqseptence Group) between 1973 and 2008 [28] 51 Figure 18: Vacuum pipe installed in existing channels; the PE pipe is attached to the wall of the channel [46]. 54 Fraunhofer IGB Vacuum sewer system GIZ GmbH II | IV Figure 19: Layout of the sanitation and reuse concept in Outapi, Namibia [39]. 56 Figure 20: Schematic overview on how water management was designed in DEUS 21 with vacuum sewers being the selected technology for wastewater conveyance [40] 57 Figure 21: Left: Garbage disposal unit in kitchen sink; Right: Vacuum toilet [1] 58 Figure 22: Black water and grey water are separately collected in separate collection sumps within the same collection pit of the vacuum system [43] 59 Figure 23: Vacuum station in Böblingen-Dagersheim 79 Figure 24: Collection pit in Waldsee. Access is restricted due to construction of wooden terrace. Access to the collection pit should be kept clear. 79 Figure 25: Vacuum tank placed in hedge in Waldsee. The components of the vacuum station have been integrated in the hedge instead of a building. 80 Figure 26: Collection pit with vacuum valve in Walldorf. The collection pit is located on a drivable road made of concrete. Respective measures were implemented. 80 Figure 27: Vacuum tank constructed underground at the vacuum station in Walldorf. The relevant pipe connections and sensor provisions are located at the top of the tank. 81 Figure 28: Biofilter with additional aeration pipe at the vacuum station in Walldorf. Plants grow on the filter material. 81 Figure 29: Vacuum tank at the vacuum station in Knittlingen. The wastewater pumps are placed outside the tank. 82 Fraunhofer IGB Vacuum sewer system GIZ GmbH III | IV List of Tables Table 1: Pipe diameters and the relation to maximum flow per minute and maximum number of served households (data from [3]) 11 Table 2: Approximate investment costs for selected components of vacuum sewers under conditions in Germany 26 Table 3: Cost of PE and PVC-U pipes per meter for different diameters under German market conditions; note that material for PE is more expensive but the prices for PVC pipes include solvent welding (not included for PE) and are thus higher [18] 27 Table 4: Costs which can vary significantly by region and affect the investment costs 28 Table 5: Selected tasks and their approximate duration (values based on experiences in Germany and the USA) 32 Table 6: Approximate material costs for selected components of vacuum sewers 34 Table 7: Potential other costs related to O&M of vacuum sewers 35 Table 8: Durability of major components of a vacuum sewer network [2, 10, 12, 12, 18, 23, 24] 36 Table 9: Overview of normal and preventive maintenance tasks and their frequencies