v RESEARCH
Manufactured topsoils at the Olympic Park – a review of soil health ten years on One of the first major urban regeneration projects in the UK to use designed and manufactured soil is assessed – and the results are impressive. Tim O’Hare
In 2010–2011, 48,000 cubic metres of manufactured topsoil was imported for the first phase (pregames) of the Queen Elizabeth Olympic Park (QEOP). It was one of the first major urban regeneration projects in the UK to embrace the concept of designing multiple soil systems for specific landscape applications and, at the time, the use of this volume of manufactured topsoil to create an urban park was unprecedented.
Early this year, Tim O’Hare Associates (TOHA) completed a follow-up survey of the Park’s manufactured topsoils to assess their current health. The data from this latest survey has now been compared with the data from surveys TOHA carried out in 2010 during the main construction period, and in January 2012 on completion, and the results are exciting. Background Healthy soils are a vital component in the delivery of ecosystem services, SuDS, various nature-based solutions and carbon sequestration, and are a key agent in fighting climate change and improving habitat resilience. Comprising a balance of physical, chemical, and biological properties, they are susceptible to rapid deterioration if not managed correctly,
and some of the most significant negative impacts result from construction activities. Remediation operations to deal with the QEOP’s industrial past yielded no reusable soil for landscape purposes and so all topsoil and subsoil had to be imported. The landscape design presented an extremely broad and ambitious range of planting environments, and each had to be catered for from a soil perspective. Requirements for specific soil pH, lime content, fertility status (high and low), organic matter content, drainage capacity, and water retention, meant that more than one soil type was required, as shown in the pie chart below. Of the soils used on the Park, the multipurpose topsoil, low fertility topsoil and high permeability topsoil
750 1682
750
3969 16449
Subsoil Multipurpose topsoil
36176
Low nutrient topsoil High permeability turf soil Moisture retentive turf soil iver edges and wet R woodland topsoil
23219
62
Structural tree soil and tree sand
