Sludge trap SAND S


The sedimentation basin SAND trap S is a settling chamber for rainwater runoff and industrial wastewater made by a reinforced concrete tank.

SAND and sludge trap S storm water runoff treatment. Model section.

SAND TRAP S – Model section

According to European standard EN 858-2 light liquids separators can have a sedimentation tank or sludge / sand trap integrated or realized in a separate unit.
The sedimentation basin, also called trap for mud or sludge chamber, is a compartment of settling for all wastewater discharged into sewer, like rainwater runoff or industrial wastewater such as car washes. It’s equipped inside with some baffles and inlet and outlet pipes with diameter suited for flow rate.

SAND and sludge trap S storm water runoff treatment. Model plan.

SAND TRAP S – Model plan



The sedimentation basin type SAND trap S is used as a component of sewage treatment plants that treat rainwater run-off and wastewater from industrial or commercial activity.
It can also be used either alone for example installed on the line of whitewater for the treatment of rains coming from paved surfaces or garages. It is used fto remove sand, mud and generally is located upstream of a light fluid separator. The sand trap is made from a monobloc vibrated concrete tank with ribs and a reinforcement beams.
Domestic waste water containing organic pollutants, or gray water are not allowed to be discharged in the sand trap, only rainwater run-off impermeable surfaces or effluents from industrial activities containing sands and light liquids. The grit removal system can be matched to a treatment plant for rainwater resulting from paved surfaces run-off, areas in which taking place hazardous activities such as recycling depot, gas stations, contaminated materials storage, entire areas devoted to parking of vehicles from workers and customers, garages and wreckers or industrial wastewater.The sludge trap always precedes the oil water separator (or light liquids separator) as defined for specific cases by the EN 858-2.


Technical Specifications

The sediment trap SLIDE S is made of a vibrated reinforced concrete tank for underground installation or above ground (available on request). Cover designed for light or heavy traffic with manhole made by concrete, galvanized steel, stainless steel.
The range of SAND trap S is available with nominal size models from 15 to 400 with three different versions.
The different versions of SAND trap S refer to the density factor for the relevant light liquid: fd specified by the European Standard: NS 100, NS 200 and NS 300. For a more accurate characterisation of the fd parameter consult table A1 of Appendix A of the standard EN 858-2.

Gross dimension are shown in table as follow.

NS DN B L H vxNS H1 H2
Name [-] [mm] [cm] [cm] [cm] [l] [cm] [cm]
SAND S 8/100 8 160 115 115 115 100 89 84
SAND S 20/100 20 200 135 240 110 100 85 80
SAND S 25/100 25 250 140 240 132 100 97 92
SAND S 4/200 4 125 115 115 115 200 92.5 87.5
SAND S 10/200 10 160 135 240 110 200 89 84
SAND S 12/200 12 200 140 240 132 200 102 97
SAND S 3/300 3 100 115 115 115 300 95 90
SAND S 6/300 6 125 135 240 110 300 92.5 87.5
SAND S 9/300 9 160 140 240 132 300 106 101

NOTE: sizes can be changed without notice.
The letters in figures and table have the meanings set out below:

L – total gross length
B – total gross width
H – total gross height (excluding cover)
H1 – inlet pipe height
H2 – outlet pipe height
DN – pipes nominal diameter

Sizing of the sludge trap

The sedimentation compartment, also known as sediment trap, is designed in relation to the expected inlet mud volume that varies depending on the kind of activity. This parameter is defined in European standard EN 858-2 and it is specific for each settlement compartment the nominal size referring to the different parameters.

The following table summarises the cases defined by the standard and the required volume depending on the activity with a few notable exceptions (Table 5 – EN 858-2)

Volume of sludge trap Quantity of sludge Application
NS 100/fd a) Small Processing wastewater with defined small sludge volume Catchment basins on petrol tank areas
NS 200/fd b) Medium Petrol stations, vehicle parking lots, garages
NS 300/fd c) High Carwash, truck wash places

a – not valid for separators with NS ≤ 10, except for covered parking area
b – minimum sludge trap volume 600 liters
c – minimum sludge trap volume 5000 liters

fd is defined by the EN 858-2 as the density factor for the relevant light liquid explaned in ‘Appendix A of the same rule.
The bulk density factor depends on the density of the lighter fluid to be separated from the implant and combination of separation light liquids.

For further information and tailor made solutions, please contact technical office.


Diagram Drawing

SAND and sludge trap S for rainwater sedimentation. Technical section.

SAND TRAP S – Technical section

SAND and sludge trap S for rainwater sedimentation. Technical plan.

SAND TRAP S – Technical plan



The sediment basin SAND trap S is designed in according to European standards.
AZU Water is available to develop solutions tailored to the particular needs of the customer.