When the water level reaches the grated intake at the top of the filter, excess stormwater is screened and filtered into an infiltration tunnel or storage system.
Graf Infiltration Filter Shaft Overview
- 3-stage cleaning process
1) Coarse filter insert
2) Fine filter basket (0.35 mm mesh width)
3) Sedimentation zone
- Filters impurities that could have a negative effect on percolation performance
- Ideal as a yard inlet or as swale percolation inlet element
- Suitable for vehicle loading with cast iron cover (standard)
- Variable installation depth from 22.5" – 41.3"using telescopic dome shaft
- Selectable 4” and 6” connections
- Maximum 3,750 sq. ft. sealed surface with 4” pipe connection and 5,400 sq. ft. with 6” connections.
- Cleans rainwater before percolation. Ideal for parking areas and as a swale percolation ditch overflow
- Equipped with handle for easy removal of the sieve inserts
- Ensures long-term function of the percolation system
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Typical infiltration application:
Swale ditch stormwater solutions:
Using Graf percolation filtration systems, infiltration through swale-ditches can be accomplished regardless of soil conditions. Depending on the soil’s infiltration/adsorption performance (Kf), stormwater control can be achieved through a balance of infiltration and retention.
For delayed outflow into the drainage system, the Graf Choke Drain Shaft is the ideal solution. By adjusting the variable choke drain aperture, stormwater flow to the drainage field can be precisely controlled while providing a parallel path for emergency overflow.
A secondary benefit of swale-ditch infiltration is the cleaning effect the soil layer provides for the rainwater. This characteristic makes it particularly suitable for larger projects having higher levels of pollution in the surface water as occurs frequently in industrial applications.
Infiltration Filter Shaft Dimensions:
Infiltration Tunnel Example:
Additional Resources:
Click here for USDA Natural Resources Conservation Service Michigan Guidelines for Kf Values.
Click here for USDA Major Land Resource Area (MLRA) Soil Survey Regional Offices
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