THE IMPORTANCE OF SOILS FOR SUCCESSFUL DEVELOPMENT HELEN SIMPSON

THE IMPORTANCE OF SOILS FOR SUCCESSFUL DEVELOPMENT HELEN SIMPSON 1

NATURAL MINERAL SOILS The surface layer of the Earth s crust composed of weathered rock, organic matter, water and air. Soil is typically divided into horizontal layers (horizons). Topsoil and Subsoil. Typically the top 1.2 m. Provides habitat for plant growth, carbon storage, water and air filtration, support for buildings, protection of archaeological artefacts, biodiversity. I.e. Ecosystem Services. Focus of presentation is mineral soils, not peatlands as that would be a talk in itself. Although Wardell Armstrong conduct a lot of peat work and many of the issues are transferable. Soil Scientists have a different definition of soil than engineers, so I thought I d start with defining what we mean by soil. Soil is the surface layer of the Earth s crust composed of weathered rock, organic matter, water and air. Also biologically rich - contains a vast array of micro and macro organisms. Soil type is dependent upon many factors such as climate and the parent material etc. Soil Survey of England and Wales recognises 720 different soil series (distinct soil types) Soil is typically divided into horizontal layers (horizons) which can be distinguished by obvious changes in physical features, chiefly colour and texture. At the most basic level this is Topsoil and Subsoil: Topsoil comprises the upper more organic rich horizon(s), whereas subsoil comprises the lower horizon(s). Typically considered to be the top 1.2 m (in UK), but varies hugely. However, no matter their depth, all soils provide essential Ecosystem Services (see list on slide) 2

THE NATIONAL PLANNING POLICY FRAMEWORK (NPPF) 2012 Promotes the re-use of brownfield land over greenfield development. (Provided that it is not of high environmental value). On agricultural land promotes use/loss of poorer quality land. LPAs to take the economic and other benefits of the best quality (BMV) agricultural land into account in planning decisions. Consequently, soil resources and BMV agricultural land are to be considered and protected from development, where their importance overrides the economic benefits of the development itself. The importance of soils and agricultural land, particularly best and most versatile agricultural land, is reflected in planning policy. Paragraphs 111 and 112 of The National Planning Policy Framework (NPPF), 2012 promote the sustainable management and protection of soils and agricultural land consistent with the economic, social and environmental needs of England. Para 109 = Ecosystem Services Read summary on slide Very similar protection offered by Planning Policy Wales. Gradually filtering down into Local Planning Policy as new Local Plans are developed and adopted. 3

AGRICULTURAL LAND CLASSIFICATION (ALC) Standardised method for classifying and assessing the quality of agricultural land. Five grades: Grade 1 - Excellent Grade 2 - Very good Grade 3 - Good to Moderate (Subgrade 3a - Good; Subgrade 3b - Moderate) Grade 4 - Poor Grade 5 - Very poor ALC - Standardised method for classifying and assessing the quality of agricultural land. Assesses land according to its versatility, productivity and workability, based upon inter- related parameters including climate, relief, soil characteristics and drainage. England and Wales ONLY. Separate system in Scotland Land Capability Classification for Agriculture (ALC is determined using Agricultural Land Classification of England and Wales: Revised guidelines and criteria for grading the quality of agricultural land (MAFF, 1988)). Five Grades see slide - ranked from excellent to very poor 4

BEST AND MOST VERSATILE (BMV) Land of Excellent, Very good and Good agricultural quality Grade 1 Grade 2 Subgrade 3a Provisional 1:250,000 ALC mapping Does not identify ALC grade at the field level Only shows Grade 3. Limited coverage of detailed data. Source: Magic.gov.uk BMV defined in the NPPF and Planning Policy Wales, The Town and Country Planning (Development Management Procedure) Order, 2010 etc. using ALC grades BMV land is afforded a degree of protection against development within planning policy. There are ALC data for the whole of England and Wales - Provisional ALC Mapping 1:250,000 scale. This has 2 limitations: cannot be used to identify ALC grade at the field level (areas of different grade <80 ha not picked up); and does not provide division of Grade 3 into Subgrades 3a (which is BMV) and 3b which isn t BMV). NB many of the surveys were undertaken prior to 1984 when the 3a/3b subdivision was introduced. Discrete areas were mapped by MAFF, now Defra, in more detail (between 1989 and 1999), but they have limited coverage and often are in areas which were proposed for development or being considered for inclusion in Local Development Plans. In some cases - dependent upon the nature and scale of development and the quality of available data; Wardell Armstrong are often able to negotiate a desk based assessment approach with Local Planning Authorities and statutory consultees such as Natural England and the Welsh Government. This is typically the case for small sites where land quality is predicted to be low. However, on large sites or where BMV is likely to be encountered, survey is required. 5

SOIL SURVEY Standardised soil survey methodology described by Natural England Identifies the soil resource Feeds into ALC calculations Distribution and area of ALC grades (& BMV) Assessment Mitigation by design Natural England TIN049 (2012) - promotes the use of Agricultural Land Classification (ALC) for assessing the quality of farmland, to insure informed choices are made about its future use within the planning system. Provides methodology for soil survey. Free-form survey methodology Allows the soil scientist to use their expert knowledge to assess the site and adjust sample locations and frequency where geomorphological, biological or land use features indicate a likely change in soil type or agricultural land quality. Thereby giving more robust survey data. But density is approx. 1 per ha. Mainly auger cores, but with 1 soil profile pit every 10 ha (or one soil profile pit per site if smaller than 10 ha). Identifies the nature and properties of the soil resource present at the site the importance of this will be discussed later ON AGRICULTURAL LAND Soil survey feeds in to ALC - determines distribution of ALC grades across the site AND presence / absence of BMV. Allows assessment of development proposals against planning requirements (NPPF etc.) in relation to soils and land quality. Historically commonly asked to undertake soil survey / ALC at the 11 th hour to meet a planning submission requirement or further information request viewed by some as a tick box exercise. So the Soils Team at Wardell Armstrong have worked hard to promote the importance and benefits of considering soils (both agricultural and non-agricultural) at an early stage of the development process, as this delivers many benefits to both the developer and the environment. 6

Firstly Mitigation by design IF conducted at an early stage of the development, ALC Mapping allows agricultural land quality to be considered in the design process. EXAMPLE on slide site is single agricultural field Provisionally mapped as Grade 2. Survey showed 1, 2 and 3b. Draft masterplan - permanent development was to be to the directed to east of site (Grade 1). Working with engineers and the wider development team, Wardell Armstrong negotiated a change to direct development to the south west (mainly 2 with some 3b and non-agricultural land). Highlights the importance of considering soils at an early stage, as directing development to areas of lower quality land better meets the requirements of planning policy (and may make it easier to obtain planning approval) and preserves higher quality soils in-situ (even if they were removed from agricultural use). 6

SOIL SURVEY The importance of soils is not limited to agricultural and/or undisturbed land. Brownfield sites Soils may be: Scarce Damaged or disturbed Contaminated. Often combine traditional soil survey and ground contamination testing. Is the soil is suitable and/or safe for reuse? Before going further, important to acknowledge that the importance of soils to successful development is not limited to agricultural or undisturbed land. More and more of the survey and resource management work Wardell Armstrong undertake is for soils within previously developed sites / redevelopments where the available on-site soil resource can be scarce, damaged or disturbed, and may have been subject to contamination. So in addition to traditional soil survey to determine soil properties, we commonly undertake additional soil testing and work closely with our contaminated land team to identify if the soil is suitable and/or safe for reuse. 7

SOIL RESOURCE MANAGEMENT ENSURES SOILS ARE PROTECTED FROM DAMAGE AND REMAIN SUITABLE FOR REUSE ON OR OFF SITE. Incorrect soil handling, storage and reinstatement can result in a loss of soil structure, nutrient content and biological activity; and leave soils more vulnerable to erosion. Soil survey data allows site specific Soil Management Plans (SMP) to be produced. considers all elements of construction and identifies site / soil type specific requirements for soil handling, storage, transport and restoration. All soils, agricultural or brownfield, can be damaged and made more vulnerable to erosion through incorrect handling and storage. BUT having detailed soil survey data allows site and/or soil specific Soil Management Plans to be produced. These set out specific requirements for soil handling, storage, transport and reinstatement to ensure that the structure, function, nutrient content and biological activity of the soil is maintained; and importantly that they remain suitable for reuse on or off site. Also it ensures that the soils can continue to provide the Ecosystem Services discussed earlier. 8

SOIL MANAGEMENT PLANS Powerful tool in maximising the reuse of existing on-site resource and ensuring its suitability for reuse in the redevelopment. Increasing trend for LPAs / Statutory Consultees to request draft SMP pre-consent. Construction Phase SMP produced by the contractor based on the draft. So SMP are a Powerful tool in maximising the reuse of soil resources and ensuring their suitability for reuse in the redevelopment or elsewhere. AND when reused in site in making sure that the soils are restored properly, function well and provide the Ecosystem Services mentioned earlier. Increasing trend for both LPAs and statutory consultees to request outline SMPs pre-consent. To ensure soils are actively considered at the planning stage. A typical arrangement would be the preparation of an outline MP during the planning process followed by preparation of a detailed (construction phase) plan (based upon the draft) by the appointed contractor working together with a specialist technical advisor, such as Wardell Armstrong. SMP typically contains items such as, but not limited to Map and description of different soil types present; A plan showing areas to be stripped, haul routes and storage areas; Soil balance, (which I will come onto later); Description of site specific excavation, storage and reinstatement methodologies; Stop conditions stating when the weather conditions and soil properties become unsuitable for handling Details of mitigation measures and methods to prevent erosion and sediment and leachate entering watercourses or drainage; Details of use of temporary working surfaces, such as portable trackways; Details of remediation measures for damaged soils (again discussed later); Requirements for records keeping and monitoring; and 9

Details of aftercare. Importantly the SMP and the methods described in it must be consistent with the requirements of other disciplines and site constraints, such as specific hydrological conditions or the presence of rare or particularly sensitive vegetation / habitats. 9

MAXIMISING REUSE / MINMISING COSTS Incorrect soil handling = delays and remediation costs. Remediation of inherited damaged soils can save thousands. Recently saved a project 90,000 on topsoil material import by enabling reuse of on-site soils. Soil balance (volumes of different soil types to be excavated and reinstated within the site, and identification of soil surplus / soil importation requirements). Early identification of costs and requirements. Cost savings by maximising reuse. A typical arrangement would be the preparation of an outline MP during the planning process followed by preparation of a detailed (construction phase) plan (based upon the draft) by the appointed contractor working together with a specialist technical advisor, such as Wardell Armstrong. The production and correct implementation of a SMP can bring a range of potential benefits to a development in terms of cost savings and by avoiding programme delays. As discussed previously, incorrect soil handling can result in damage to the soil which makes it unsuitable for reuse. This can lead to additional costs for soil remediation and delays to the programme whilst these works are undertaken. Basically, do it right, do it once. Alternatively, where damaged soils have been inherited with the plot, the identification of effective remediation measures can enable these soils to be reused on site rather than exported as waste saving the project money by removing soil importation and waste exportation costs. For example, we recently saved a project 90,000 by showing that with appropriate cultivation the available on-site topsoil material could be remediated and reused on-site. Completely removing the requirement for topsoil importation. All construction phase SMP contain a soil balance. This evaluates volumes of different soil types to be excavated and reinstated within the site, and identifies where soil surplus or shortfalls occur. This allows the early identification of costs and import / export requirements. Also it allows input into site phasing and can optimise the reuse of materials onsite. 10

DELIVERING SUCCESSFUL LANDSCAPING Work closely with landscape architects to: Define the differing soil profiles and conditions. Choose species well adapted to site conditions. Minimise the risk of planting failure. Minimise replanting costs Achieve good quality landscaping in as short a time frame as possible. Our role doesn t end with ensuring that the soils are in a condition suitable for reuse on a site; or indeed in identifying suitable additional soils for importation to a site; we also work closely with landscape architects to ensure that these resources are used to the best effect. Once the landscape architect has produced the planting plan we define the differing soil profiles and soil conditions (including fertiliser and cultivation requirements) required to ensure the plan is successful delivered. Often we inform the landscape planting by providing details of soil conditions and ensuring that only plants well adapted to these conditions are chosen. For example, if site soils are acidic and prone to waterlogging, the planting plan should not include species which prefer free-draining alkali soils. This reduces the risk of additional project costs due to planting failure and also ensures that desired landscaping is of good quality and achieved in as short a time frame as possible. 11

DELIVERING SUCCESSFUL LANDSCAPING - TREES Briefly discuss landscape trees, although again they are a presentation in themselves. Trees are often a key feature or focal point of a landscape scheme and the most expensive element of the planting. But they are also probably the element most likely to fail. Planting trees in urban environments / amongst hard landscaping is challenging as the soil structure requirements to support hard surfaces capable of sustaining large weights are diametrically opposed to those of a healthy tree root network. As demonstrated in the picture, both sets of trees are the same species, of the same age, and planted at the same time. The trees to the right of the picture are planted in soils which are compacted (to support the pavement); whilst the trees to the left of the picture have access to the uncompacted soils within the adjacent grass verge. Brief discussion of differing methods of planting to ensure long-term viability 12

MANUFACTURED AND RESTORATION SOILS Where soils are not available, or where available soils are of poor quality they can be manufactured or improved through the importation of suitable waste materials. Target soil properties are chosen based on: the properties of the soil forming materials present or being imported to site; the intended land use; the surrounding environment; Requires permitting (EA /SEPA). It is also worth noting that where soils are not available, or where available soils are of poor quality they can be manufactured on site or improved through the importation of suitable waste materials; which may be more cost effective than soil importation. Soil manufacture is commonly undertaken on former industrial sites, although soil improvement is often undertaken on agricultural land - just think of muck spreading. Requires Environment Agency (EA) or Scottish Environment Protection Agency (SEPA) permitting. In the past, there was no real restriction in the volume of waste you could use to create or improve a soil, provided the levels of contamination were below threshold levels. However, new guidance (or more strictly applied guidance) now requires that waste can only be applied to the point where the maximum benefit is achieved and should not continue beyond that point. Therefore, to assist project viability, where more than one waste stream is proposed for use, our team of experts calculates the optimum proportions to maximise the overall volume of waste which can be deposited, whilst ensuring the deployment achieves the required soil parameters. The target soil properties are chosen based on the properties of the soil forming materials present or being imported to site; the intended land use; the surrounding environment. We also advise on issues such as the method of incorporation; and aftercare requirements. 13

Don t treat soil like dirt! Don t treat soils like dirt or it is liable to cost you time and money. 14

Dr Helen Simpson: Associate Director EIA specialist Soils and Agriculture Team Leader hsimpson@wardell-armstrong.com www.wardell-armstrong.com www.linkedin.com/company/96337/ 15