Drain areas in an environmentally friendly manner using multiple systems

München Klinik Bogen­hausen is of suprare­gion­al impor­tance and is one of the largest hos­pi­tals in the state cap­i­tal. As part of a mod­ern­iza­tion and exten­sion project, the hos­pi­tal is being equipped with a state-of-the-art oper­at­ing the­ater and offers more than 1,000 beds. In the course of the mod­ern­iza­tion, the drainage of rain­wa­ter was also redesigned.

Cleaning rainwater from heavily polluted areas

Around 3,400 m² of sealed and in some cas­es heav­i­ly pol­lut­ed traf­fic areas, includ­ing a heli­pad, as well as almost 4,000 m² of roof sur­faces have to be drained. The rain­wa­ter runoff is returned to the nat­ur­al water cycle of the ground­wa­ter via infil­tra­tion trench­es. Before being dis­charged into the ground, the water must be cleaned and pol­lu­tants removed.

Sinking shafts make subsequent installation of the filter system necessary

Projects of this mag­ni­tude require com­plex plan­ning. In this case, it had to be tak­en into account that the sub­soil for the infil­tra­tion con­sists large­ly of Isar grav­el. As a result, it was unclear for a long time whether the con­crete shafts for stormwa­ter treat­ment plants could be placed as stan­dard. It was decid­ed to use sink­ing shafts, which are placed piece by piece into the sub­soil with­out allow­ing the sur­round­ing loose soil with Isar grav­el to slide down. Usu­al­ly, water treat­ment plants are brought com­plete­ly into the ground with the shaft. This is not pos­si­ble when sink­ing. There­fore, the deci­sion was made to use the 3P Hydrosys­tem for the water treat­ment. The unique fea­ture of this sys­tem is that the entire fil­ter unit can eas­i­ly be sub­se­quent­ly insert­ed into the shaft that has already been sunk into the ground.

Sedimentation, filtration, adsorption and chemical precipitation

In terms of purifi­ca­tion tech­nol­o­gy, the plant was divid­ed as a hydrosys­tem quin­tu­ple plant and a twin plant. The sys­tem com­bines sed­i­men­ta­tion process­es with a fil­tra­tion stage. Thus, the rain­wa­ter is puri­fied by sed­i­men­ta­tion, adsorp­tion, fil­tra­tion and chem­i­cal pre­cip­i­ta­tion. A hydro­dy­nam­ic sep­a­ra­tor caus­es sed­i­men­ta­tion of solids in a radi­al flow regime char­ac­ter­ized by sec­ondary flows. As a result, solids enter a flow-calmed sludge trap locat­ed below the sep­a­ra­tor hopper.

Four fil­ter ele­ments are arranged above the sep­a­ra­tor cham­ber. The water is passed through in an upflow process. The fil­ters remove pol­lu­tants such as heavy met­als, petro­le­um hydro­car­bons and poly­cyclic aro­mat­ic hydro­car­bons from the stormwa­ter. Nutri­ents such as phos­phates are also bound. The qual­i­ty of the puri­fied water is so high that it can be dis­charged direct­ly into infil­tra­tion or any oth­er receiv­ing water. In addi­tion, a pure sed­i­men­ta­tion plant 3P Hydroshark of the dimen­sion DN 1,500 was used for the purifi­ca­tion of runoff from less pol­lut­ed areas.

Minimum space requirement due to installation under traffic areas

The 3P Tech­nik Hydrosys­tem plants do not require any addi­tion­al space on the prop­er­ty or in the road space, as they can be installed under the traf­fic sur­face. They are suit­able for stormwa­ter runoff from all sur­faces such as roofs, traf­fic areas or indus­tri­al sites. The clean­ing per­for­mance is designed to reli­ably meet the require­ments of Code of Prac­tice DWA‑M 153, Work­sheet DWA‑A 102 and the NRW Sep­a­ra­tion Decree.