Design
It is the designer's responsibility to ensure that suitable qualified engineers are engaged to ensure hydraulic and structural design of both infiltration and attenuation systems.
MetroCell Installation
Pre-installation notes and guidelines can
be supplied on request. Please contact the
Naylor Sales Office for more details.
General Guidelines - Backfill Material
For landscape and non trafficked areas:
Selected ‘‘as dug’’ material with a unit size no more than 75mm compacted to 90% maximum dry density. Compaction equipment on top of the system NOT to exceed 2,300kg per metre width.
For trafficked areas (car parks etc)
Type 1 or 2 sub base material compacted in 150m layers. Compaction equipment on top of the system NOT to exceed 2,300kg per metre width.
Venting of Attenuation Structures
All attenuation structures require one 110mm
diameter air vent per 7,500m2 of drainage.
Maintenance
For domestic soakways, the only maintenance
necessary is to keep the house gullies and
silt traps free from debris, such as leaves;
however for larger structures a system of
regular inspections should be established
to prevent silt build up etc. Maintenance
can be divided into two areas, certain steps
can be taken to keep maintenance to a minimum.
Preventive Maintenance
These measures deal with designing into a system sufficient failsafes to ensure that future maintenance is kept to the absolute minimum.
Siltation
This is normally dealt with by the use of silt traps which should be included in every structure (both infiltration and attenuation). These silt traps should have a regular maintenance regime to ensure correct performance.
Connections positioned within the preformed
trepanned holes allow for 20mm deposit of
silt to be accommodated without affecting
the performance of the units. In the unlikely
event that it is decided that a silt build
up within the MetroCell unit is deemed unacceptable,
the units can be flushed through at any time
by capping the outlet point and filling the
structure using a water tanker. On removal,
the velocity of the outgoing water will significantly
reduce the silt levels. |
