Treating Surface & Rainwater; Filter Units - Graf EcoBloc Inspect flex Manual Para El Uso Y El Mantenimiento

5.1 Treating surface & rainwater
To ensure perfect operation of the infiltration/attenuation system, filters of sufficient sizes should usually
be fitted. These filters are required to be installed upstream of the infiltration/attenuation system.
In special cases, multi-stage filter systems with coarse and fine filters are used to treat the rainwater. The
exposure and size of the collection surfaces can be used to determine whether a multi-stage system is
needed and the size of filter required. We would be happy to help you select an appropriate filter/filter
shaft. GRAF provides an extensive range of such products.
Work sheet DWA A-138 and data sheet DWA M-153 also contain sizing examples and information about
filter stages upstream of infiltration/attenuation systems.
5.2

Filter units

The DWA data sheet M-153 provides various recommendations for working with rainwater. An overview is
provided in Table 1.
Groundwater intake
Swales
Surface infiltration
In areas with high concentrations of pollutants, several filter systems can also be combined to form one
overall filter. This firstly filters out coarse particles and then retains dissolved substances.
The layers of soil which the rainwater penetrates during the infiltration process before it reaches the
groundwater also have a filtering effect. A distance of one metre between the bed of the infiltration system
and average groundwater level should therefore be maintained during the planning phase and/or when
setting up the system in accordance with DWA A-138.
mail@graf.info
www.graf.info
5. Treating Surface & rainwater
Table 1
Retention soil filters
Sand filters
Ponds
12 / 28
Sedimentation systems
Silt traps
Purification basins for
rainwater
Filters
Coarse filters
Fine filters
Substrate filters