Woodland Tree Soil (Urban Soil, Amsterdam Tree Soil) Installation Guide


Typically for paved areas, such as town squares, road-side planting, superstore car parks, municipal car parks etc., a trench should be excavated approximately 1 metre in depth and sufficiently wide and long to accommodate a minimum of 5m³ (5 cubic metres) of Woodland Tree Soil. If conditions do not allow then individual pits should be 2.8m x 2.8m x 1m deep.

The following installation procedure has been found to be most successful:

The trench or tree pit should be backfilled in compacted layers of no more than 300mm deep, (fill loose to 375mm), each layer should be compacted as follows:

1st layer       1 pass with compactor or rammer

2nd layer     1 pass with compactor or rammer

3rd layer     2 passes with compactor or rammer

Please note: BS60Y Wacker Rammer or similar is preferred.

Final compaction can be checked using an Eijkelkamp Penetrograph fitted with a 1cm² cone. Penetration resistance should fall within 1.5-2.0 Mpa (Mega Pascals), approximately 1.3-2.2 CBR%.

It is important to understand that over compaction will stop root penetration.

Once a sufficient sized tree pit has been excavated correct installation and compaction can take place of the Woodland Tree Soil. Any site details e.g. drainage tubes or anchor systems should also be incorporated. The tree pit levels are then completed using Woodland Tree Soil.

The Woodland Tree Soil is then topped off with 150mm of compacted bedding sand with paving slabs, bricks or concrete blocks laid over the top to the required finished level.

As the type of surface detail influences the amount of air exchange between the Woodland Tree Soil and the atmosphere it is recommended to use a product that has a large amount of jointing such as brick pavers. This can be introduced into the pattern of surface detailing. For areas where there is extremely limited space a highly porous surface such as grasscrete or wide nibbed pavers are recommended.