Precast concrete SuDS components can be installed with very little imported granular, or involvement from wet trades, as demonstrated below:
The surrounding bedding is crucial for the structural design of any pipeline. The strength of an installed pipeline depends on a combination of pipe strength and the class of bedding. While flexible pipe tank systems generally use a 360° full granular bedding and surround, rigid pipes can sometimes be installed with significantly lower amounts of imported granular, leading to significant cost savings.
MPA Precast has a structural and cost calculator to help you assess what Bedding Class to use and how much imported granular you may be able to save.
Precast concrete chambers
A wide range of treatment and attenuation SuDS components, such as vortex separators, water harvesting & treatment tanks, are made of precast concrete chambers. Many of these solutions can be installed using precast base and wide wall chamber units requiring no concrete surround and saving significant time and cost on site.
For more information on precast base chamber units please check this pocket guide from MPA Precast.
Box culvert tanks
Box culvert units need to be installed over granular bedding layers or a flat apron of lean mix concrete. The nature and design of box culverts means that, in most cases, very little depth of cover may be needed, leading to further savings on bedding material needed for installation. After installation, the tank can be backfilled using appropriate backfill material with appropriate compaction where needed.
More information on box culverts can be found in the MPA Precast Technical Guide.
Post installation testing
Acceptance tests are likely to match those required for any completed drainage works and would include visual inspections to identify potential obstructions and debris, joint sealing, line and level (within tolerance) and structural soundness of the installed elements.
Pipeline installations using pipes ≤ DN900 are more difficult to inspect visually and may require an air or water test depending on the nature of installation. These tests are usually carried out prior to backfilling. For more information on Air tests, please check this video from MPA Precast: https://www.youtube.com/
