Prevent soil damage during construction projects
Sourcing, importing and manufacturing topsoil
Before you consider importing topsoil, your soil resources survey should have fully investigated the suitability of all on-site resources for your project. If a shortfall in topsoil is identified, the survey should consider the potential to manufacture topsoil from surplus subsoil. However, you should consider the cost implications. For more information on surveys, see consider soil protection before construction begins.
If you need to obtain topsoil from an off-site source, there are a broad range of soil-based materials sold as topsoil, but not all of these are suitable for the intended purpose. You should check whether they meet the specifications in British Standards Institution BS 3882:2105 Specification for Topsoil and Requirements for Use.
Natural topsoil
Natural topsoil comes from the development of greenfield sites and, sometimes, undisturbed and uncontaminated areas of brownfield sites. As a result, its availability often depends on such a site being developed simultaneously nearby.
Whilst many topsoils are suitable for general landscaping, those with more extreme characteristics are not. For example, a silty soil is excellent for agriculture, but its weak structure may mean it isn't appropriate for landscaping. Temporary storage can also make topsoil unsuitable for its intended use without appropriate improvement - see how to manage soil during construction.
Manufactured topsoil
Manufactured topsoil can be produced by mixing appropriate mineral and organic materials to create a rooting medium. Blends can include components such as natural topsoil, sand, overburden, subsoil, green compost and treated biosolids.
If the correct components have been selected and blended to the appropriate ratios, this can offer an excellent alternative to natural topsoil. But you should beware of manufactured topsoil that uses unsuitable additives or without the necessary quality control measures.
Skip waste soil
Skip waste soil is derived from screening materials from 'muck away' site clearance operations. The coarse element is screened out and used as recycled aggregate, whilst the fines are often sold to an unsuspecting buyer as 'general purpose topsoil' or 'turfing soil'. It's generally a mixture of:
- topsoil
- subsoil
- clay
- building waste - for example fragments of brick, concrete, mortar, ash, clinker, asbestos, glass, metal, wood and plastic
It's usually extremely alkaline, saline and infertile - and often contains high levels of chemical contaminants such as heavy metals and hydrocarbons.
Topsoil assessment
Don't accept non-documented or unverified topsoil. You should always use a reputable supplier, establish its source and analyse whether it is appropriate for your intended purpose.
It's wise to have the soil independently sampled and tested by someone suitably qualified, for example a member of the British Society of Soil Science.
Your requirements will depend on the required performance of the topsoil - so may differ for different planting plans.
Manufacture your own topsoil
Manufacturing your own topsoil can offer many benefits, including:
- cost savings
- reduced transport movements
- reusing surplus subsoil
- recycling materials
- reduced landfill costs
- allowing you to alter mixing ratios to suit planting requirements
Topsoil manufacture can be carried out on-site or off-site.
On-site methods involve spreading out and incorporating the organic and mineral components directly at the soil's final location. Although efficient, this approach is better suited to large, open areas that are accessible to tractor-drawn machinery.
Off-site methods involve blending the components using mobile quarrying and civil engineering machinery before transporting the soil to its final location. This approach is better suited to manufacturing topsoil for smaller areas that are inaccessible to larger equipment.
Waste legislation and topsoil
Surplus soil that only leaves its site of origin temporarily is not considered to be waste - so is not subject to waste management controls. However, imported soil and organic ameliorants (such as soil conditioners) are subject to waste management controls - so an environmental permit or waste exemption must be in place. If you're unsure if a permit or exemption is needed, you should check with the Department for Agriculture, Environment and Rural Affairs (DAERA).
Composted materials produced to the PAS100 standard that comply with the compost quality protocol are considered to have ceased to be waste - so waste management controls do not apply.
You can also download a code of practice for soil use on construction sites (PDF, 737K).