Site preparation

Tree planting is unlikely to be adopted unless the appropriate guidance has been adhered to. The ground of all areas to be soft landscaped must be landscaped in accordance with clause 3004 of the  Manual of Contract Documents for Highway Works (MCHW) and Appendix 30/4 of the council’s Specification.

Soil condition

For the long-term health of planting schemes, and particularly tree planting, it is necessary to assess the condition and extent of the soil below ground. A soil survey should be carried out before planning or designing any new landscaping and remedial works to identify and treat poor ground conditions. It is a waste of time and money to plant trees and shrubs into damaged and poorly prepared soils.

Soil compaction and contamination

During construction activities, surrounding soils can become damaged by compaction and contamination. It is essential that they are treated so that they can support new planting and sustain normal plant development. Compaction can be improved by deep ripping or cultivation (or both), which allows oxygen to penetrate the soil and improves drainage.

Badly contaminated soil must be removed from the site and replaced with fresh topsoil. It is also beneficial to apply an organic surface mulch such as pulverised bark to a planting area. Please refer to Department for Environment, Food & Rural Affairs DEFRA: Construction Code of Practice for the Sustainable Use of Soils on Construction Sites.

Hard surfaces close to the planting site must be designed to withstand interference from developing roots. This can be achieved by using a sub-base that is load bearing and contains a proportion of soil and air space, or by using root deflectors. Adjacent hard surfaces should be permeable to allow drainage and oxygen penetration to the soil below.

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