HOBAS Storage System Heidelsteinstraße
The collection and discharge of storm- and wastewater represents a daily challenge for wastewater facilities and municipalities. In combined systems, domestic, commercial, and industrial sewage and stormwater are all transported to the wastewater treatment plant by one shared sewer. Due to an increase in heavy rain events, sewers are frequently surcharged and wastewater treatment plants reach their capacity limit. For the system to operate flawlessly even at peak times, stormwater retention basins are installed at suitable points. In combination with overflow structures, they regulate the water quantity to be led to the wastewater treatment plant. The retention basins serve as temporary storage from which the wastewater is gradually discharged.
HOBAS offers two alternatives to conventional retention basins: the HOBAS CSO (Combined Sewer Overflow) Chamber, a modular overflow system for combined sewers with low-maintenance solids separation, and GRP storage systems.
HOBAS GRP Storage Systems
Storage systems are employed when the installation of open retention basins is not possible due to space limitations (e.g. in city centers). Both products operate essentially in the same way: In events of heavy rainfall, the incoming water is first accumulated, then throttled and led into the subsequent sewer system. Leftover deposits of suspended solids in the sewer are washed out with the next rain and conveyed to the wastewater treatment plant. Thanks to the very smooth inner surface of HOBAS GRP Products, the sewer system is practically self-cleaning and requires hardly any maintenance. A practical example for such a storage system is the project Heidelsteinstraße in Fulda, Germany. Since the stormwater and sewage system was overburdened and in urgent need of rehabilitation, a new combined sewer was to be built and connected to a HOBAS GRP Storage System DN 3000.
The installation of the originally designed concrete structure proved to be too costly, which is why GRP was chosen as an alternative. Apart from the overflow structure, the whole storage system is made of GRP, i.e. even the throttle and connecting structure as well as the intermediate shaft. The 3.5 m difference in height on a length of approximately 8 m represented a particular challenge when connecting the overflow structure to the adjacent stream. No problem for HOBAS Experts though: The difference in altitude could be easily compensated by means of a swan-neck bend with an angle of 45°. The completely prefabricated modules were easily installed and connected to the combined sewer. At the beginning of 2013, the construction works were completed to the satisfaction of all parties involved.