Prevent soil damage during construction projects
The pressures on soil in the built environment, and how to manage soil effectively during building and landscaping.
Soil is a fundamental and irreplaceable natural resource. Its key functions include providing food and raw materials, 91香蕉黄色视频ing wildlife and regulating the flow of water.
Despite its importance, the management of soil has often not been given consideration during construction and landscaping projects. Poor understanding of soil management during the construction process has led to problems of soil infertility and compaction, valuable topsoil being sent to landfill, and led to some developed areas being prone to flooding.
Taking steps to ensure good soil management can help your business cut costs and improve its image and environmental performance.
This guide summarises the key pressures on soils in the built environment and the benefits of managing them sustainably. It includes good practice techniques for stripping, stockpiling and spreading soil. It also contains guidance on sourcing and manufacturing topsoil, soil aftercare, and finding sustainable uses for surplus topsoil.
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Benefits of managing soil in the built environment
Environmental and economic advantages of managing soils effectively during your construction projects.
Construction and landscaping can have an enormous impact on soil quality within the urban environment. Using techniques that maintain soil quality and function will help you ensure that soils can continue to maintain drainage characteristics, 91香蕉黄色视频 vegetation and provide the basis for green spaces, while minimising the risk of causing flooding or erosion. In addition to these environmental benefits, such sustainable business practices can help you reduce your costs and enhance your reputation among clients.
Policymakers are looking at how soil can be protected through legislation and good practice. For instance, planning authorities increasingly require sustainable drainage systems for new developments.
You can cut your soil management costs with effective forward planning and management before and during construction activities. If possible, you should aim to reduce the need to double handle your soils. This will help prevent problems such as compaction and poor drainage and, in some cases help avoid unnecessary importing of soils for landscaping. Finding a sustainable use for any surplus soils could also mean further savings - as well as making it easier to comply with waste legislation.
You can improve your reputation with regulators, customers and other stakeholders by showing that you consider environmental issues to be a priority - see market your environmental credentials.
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Pressures on soil in the built environment
An overview of construction industry practices that have the potential to damage or restrict soil function.
Soils provide various important functions and services for society, including water infiltration, flood mitigation and the protection of valuable biodiversity. They need to be protected and managed to optimise these functions. Construction and development activities can damage the soil, preventing it from carrying out these natural functions.
Renewing soil
If soil is permanently removed and not reused, this could result in the loss of an irreplaceable natural resource. Topsoil is particularly valuable because of its fertility. You should find a sustainable use for any waste topsoil rather than send it to landfill - see uses for surplus topsoil.
Stockpiling soil
When soil is stockpiled there is a risk of it being mixed with subsoil components and other construction materials, which reduces its quality. There's also a risk of the stockpiled soil becoming compacted and eroded by the weather. If you keep too large a stockpile of topsoil, it can result in a loss of quality through lack of oxygen. For more information on soil stockpiling techniques, see how to manage soil during construction.
Compacting soil
Compaction is a common problem during construction projects. Poor soil handling techniques, inappropriate on-site storage of materials and trafficking - particularly by heavy machinery - can all contribute. Lack of oxygen and poor drainage in compacted soil restrict its ability to 91香蕉黄色视频 vegetation.
Sealing soil
If soil is sealed - ie covered with an impermeable material - it's prevented from functioning properly. As well as removing an area that could 91香蕉黄色视频 vegetation, this also damages a natural drainage characteristics. As sealing will occur as a result of development, you and your client should consider how to minimise the footprint of any building and try to reduce the loss of soil function. For information on protecting soil function and sustainable drainage systems, see consider soil protection before construction begins.
Contaminated soil
There are many types of soil pollution and contamination - including chemical spills and building rubble. These can all contribute to a loss of soil function.
Importing soil
Importing soil is common practice for landscaping projects. Unfortunately, this is often accompanied by a poor understanding of soil management. This can result in unsuitable soil materials being imported or some of the problems described above, such as compaction or contamination - see sourcing, importing and manufacturing topsoil.
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Consider soil protection before construction begins
The importance of a soil resources survey prior to any earthmoving, and information on sustainable drainage systems.
You should arrange for a soil resources survey to take place before any earthmoving operations start. This should be carried out by a suitably qualified and experienced soil scientist or practitioner - for example . You should not rely on a geotechnical or geo-environmental survey for this - the soil resources information won't be detailed enough.
You should use the results of your survey to help you manage your soil more sustainably - for example, by developing a soil management plan and budget (and identifying deficiencies or surplus requirements), which can be updated as site planning progresses.
You could also consider using new technologies which can return some of the lost soil management plan and functions to the built environment. Examples of techniques used by these sustainable drainage systems (SUDS) to replicate natural systems include:
- permeable paving - porous materials or voids within areas of solid paving to allow water to drain through, reducing flooding
- green roofs - roofs covered with vegetation, which reduce the volume and rate of rainwater run-off and provide good design and compatibility for the local area
For more information, see sustainable drainage systems (SUDS) for business.
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What is a construction soil management plan?
The importance of having a soil management plan in your construction projects for environmental protection.
A soil management plan is an important part of ensuring soil sustainability during construction projects. Without a soil management plan there is a risk of losing, damaging or contaminating valuable soil resources, whether the soil will be retained for future landscaping on-site, or used or sold off-site.
What a soil management plan should contain
Your soil management plan should include:
- maps showing topsoil and subsoil types and areas to be stripped
- methods for stripping, stockpiling, respreading and improving the soils
- haul routes
- location and content of each soil stockpile
- schedules of volumes for each material
- expected after-use for each material
- who is responsible for supervising soil management
If your construction site doesn't have room to stockpile soil, it might make sense to find a sustainable off-site use for the temporary surplus and then import suitable soil later. However, you should consider the costs that this may involve.
You should ensure that any areas of soil that need to be protected from construction activities are clearly marked out by barrier tape and exclusion signs. Any haul routes should be stripped down to a firm base and be no wider than necessary to accommodate two passing vehicles.
Topsoil and subsoil stripping
Topsoil is a finite and valuable resource due to its fertility. Before beginning work on your construction site, you should strip the topsoil from all areas that will be disturbed by construction activities or driven over by vehicles.
Subsoil isn't as fertile as topsoil, but - because of the vital role it plays in storing and transmitting water - you should still minimise any damage during stripping. Subsoil in areas designated for landscape plantings often just needs to be protected from damage rather than stripped. However, you should remove subsoil from all areas that will be disturbed by construction activities or to make way for haul roads.
There are a number of best practice measures you should follow when stripping topsoil or subsoil to avoid soil damage as much as possible, such as:
- using tracked machinery
- carrying the work out in the driest conditions possible
Soil stockpiling techniques
To enable soil to be reused on site at a later stage, it needs to be stored in temporary stockpiles to minimise any damage or loss of function. There are a number of important considerations when creating stockpiles - including soil erosion, pollution to watercourses and the risk of flooding. These will be affected by the size, height and method of forming your stockpiles, and how they are protected and maintained.
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Create landscapes, habitats or gardens with construction soil
How soil spreading and cultivation techniques to reduce compaction can help to restore lost soil function.
If you are creating landscapes, habitats or gardens, there are a number of issues you should consider. For example, if you re-spread a large volume of soil that's been stockpiled or imported - particularly using heavy machinery - this can cause loss of soil structure and over-compaction.
Such damage to the soil's structure can cause a number of problems that will restrict its ability to 91香蕉黄色视频 new vegetation. For example, if plant roots are unable to penetrate the soil and take up water or nutrients, they will be susceptible to drought.
Good soil spreading and cultivation techniques can help to reduce compaction and help restore lost soil function. You should consider:
- decompacting the soil before soil spreading begins
- using appropriate machinery
- minimising any handling of the soil
- suspending work in wet conditions
You will also need to consider a number of issues when you are spreading topsoil. For example, it needs to be at least 150 millimetres deep for grass, or a thicker layer for shrubs and trees as these have deeper roots.
Make sure that you remove any undesirable materials such as stones, fill materials or vegetation larger than 50 millimetres in any dimension. You should cultivate re-spread topsoil using appropriate equipment and techniques, and ensure that you break down any compacted lumps.
Familiarise yourself with best practice for re-spreading soil for landscaping, and using and cultivating topsoil.
If you do not have the in-house expertise to carry out this work effectively, you should get a suitably qualified person or organisation to do it for you.
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Sourcing, importing and manufacturing topsoil
How to ensure imported topsoil is suitable for its intended purpose, plus waste legislation you need to be aware of.
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 .
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 .
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 .
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.
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Soil aftercare in construction
How to treat amenity grass, tree pits and planting beds after spreading in order to maximise soil function.
Structurally-weakened soil tends to settle and self-compact after it's been spread - leading to anaerobism (lack of oxygen) and waterlogging. These are the most common soil-related causes of plant failure on landscaped areas.
Even when the soil isn't compacted, it can take up to three years for the soil structure to stabilise and offer the necessary aeration and drainage for plants to grow properly.
Where a landscape contractor is used, it's common to retain their service for up to five years after installation on a 'defects liability' arrangement. Such a maintenance programme should include monitoring soil conditions to identify unsatisfactory growing conditions.
Amenity grass
Tractor-drawn or self-propelled equipment can be used to verti-drain, slit or spike the turf and topsoil. This will break-up any panning and compaction - improving drainage, aeration and root function.
Other effective treatments include:
- applying fertiliser
- applying herbicide
- top dressing with sand, soil or compost
- over-seeding to improve grass cover
Tree pits and planting beds
For trees and shrubs, it's essential to monitor conditions to identify any problems as early as possible.
Tree pits can act as sumps for draining water - this leads to anaerobic conditions, root rot and can ultimately completely kill the tree. Possible remedies include drying out the soil by opening up the pit or pumping the stagnant water out.
Applying wood mulches to planting beds can cause compaction. You can usually relieve this by spiking the soil with a hand fork between the plants. Where compaction is deeper, or on larger areas, mechanised treatment may be necessary.
You should also include fertiliser application as part of your maintenance programme - particularly for the first few years. Compound, slow-release or controlled-release fertilisers are best for tree and shrub topsoil.
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Uses for surplus construction topsoil
Suggested ways for your business to use excessive amounts of topsoil taken from your construction site.
Uncontaminated topsoil is in short supply in many places - particularly urban areas. So it's important that this vital and valuable resource isn't wasted.
Your soil resources survey and subsequent soil management plan may identify a surplus of topsoil - once the required quantity has been set aside for on-site landscaping. If this is the case, you should contact your local authority to try to identify nearby land reclamation or brownfield development sites lacking soil resources.
Waste permitting and exemptions for soil
Soil discarded from a site - rather than being moved off it temporarily - is normally classed as waste. It only ceases being waste once it has been fully recovered - for example spread back onto land as soil.
Such soil waste is subject to landfill tax - unless it's recycled or recovered under relevant waste exemptions. The main exemptions relevant to soil reuse concern the treatment of agricultural land and the reclamation or improvement of non-agricultural land.
Alternatively, the soil should be taken to an appropriately permitted treatment facility for recovery or, as a last resort, be disposed of at landfill. If the surplus soil is sent to landfill it will be subject to landfill tax.
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