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MUCK AND BRASS

TECHNICAL & PRACTICE

In March, the ODPM published the Annex to Planning Policy Statement (PPS) 23 Planning and Pollution Control to ensure that planners and developers consider contamination issues as soon as possible on remediation projects. It suggests that the key planning objective is that any unacceptable risks from the contaminated condition of land be identified, assessed and appropriate action be taken to address those risks.

In the same month, a report from the Centre for Environmental Policy and Governance (CEPG) and ERM ('the world's leading provider of environmental consulting services'), supported by the ODPM, bemoans the fact that planners currently 'face a confusing range of sources of information'; they need to deal with 'it', but they don't know what 'it' is.

The CEPG report falls back on demands for yet another regulatory Planning Policy Statement. This PPS, on environmental hazards, they propose, would address everything from flooding risks to radiation, from coastal erosion to air geological radiation. Thus a consultative document that attempts to address the pervasive influence of risk culture ends up bemoaning the fact that the planning system is becoming overly focussed on a very limited set of hazards and risks'. Such is the cycle of 'risk consciousness'.

Meanwhile, at grass-roots level, Phil Reeve, of the East Midlands Development Agency, has a more relaxed attitude to remediation. For 'contamination' needn't be as black as it's painted.

His 'leave well alone' attitude at the 'Avenue Project' in the East Midlands - the largest contaminated land project in the UK - even comes down to permitting the contaminated land to lie undisturbed in places. In this respect, Reeve seems to have an unusually healthy risk-taking approach to ground conditions.

The Avenue Coking Works in Chesterfield closed down in 1992 and is currently undergoing landforming remediation masterplanned by Rick Mather Architects. Already 16ha has been completed and the tenders for the next 83ha have just been returned. Preferred contractors will be appointed by the end of this month, details will be finalised in 12 months and work should take six years on site.

This is the biggest project that English Partnerships has ever undertaken - including fees etc it totals £104.5 million. Since 1999, more than 12,000 tonnes of ferrous metals has been recycled and other materials taken from the demolition of the coke ovens have been cleaned up for use as fill material on site.

The lessons learned from this site ought to be applied to brownfield developments of any size as remediation solutions do not always have to result in land clearance, spoil transportation and landfill. 'In the past, ' says Reeve, 'a client was given peace of mind by having everything dumped.' But with the introduction of the Landfill Directive, dumping is more expensive and clients and contractors have been driven to find other solutions. Nowadays landfill is unnecessary, provided that the design team rationally risk assesses the significance of the potential harm that may be caused.

'For years, ' says Reeve, 'the UK was the dirty man of Europe and other countries had a much better record. But some European countries have already been over-ambitious. Because the UK has had a pragmatic response to contaminants for a long time, spending money to assess the problem up front, we're well placed to offer our services and knowledge to others.' Reeve's approach is premised, of course, on a duty of care:

an educated assessment of the land and its proposed use, detailed research, calculations and the test of reasonableness. This last factor - what is reasonable to retain in any given conditions - should be more widely appreciated. Not only will it save money but it might also influence the wider debate about the perceived dangers of building on industrial land. Architects might usefully adopt this approach, for example, in projects necessitating asbestos removal;

demolition works; or working with, or building on, other hazardous waste. Source materials like DETR Industry Profiles, DEFRA and EA Contaminated Land reports, etc can to give clues to the likely costs of these issues.

Soil Guideline Values are generic assessment tools that use standard exposure values. Admittedly, these are quite limited in scope but experienced consultants can use them to justify their own specific values for each given site. For example, there is a model, say, of the hazard value for a six-year-old child playing on the site for a certain amount of time each day. This generic model takes into account the amount of soil that a generic child will have on his or her skin, or ingest, in comparison to average body weight.

This provides a complicated calculation of the threshold exposure level of contaminants per kg of bodyweight. The 90th percentile provides the final 'statistically valid' criteria. Now that these figures have been made public, consultants can use the algorithms to justify their own specific values. This tightening up of figures means importing site specific data to challenge the initial soil guideline values given.

As Reeve says, it would be extremely difficult to prove that all children who may visit the site will have more robust constitutions than the target calculation assumes - and therefore will be able to ingest more of the hazardous material - as data is thin on the ground in site-specific locations. But data from the US is 'defensible figures, based on actual rather than generic data' that can be used to fine tune the specific results that are applicable to the given site.

In this way, the soil threshold calculation can be uplifted to a higher tolerance level, albeit, as Reeve reassures, 'with a high precautionary element still retained'.

The precautionary element relates to the site context - what is near the surface in a site intended for a domestic garden cannot be at the same level as that for industrial use at depth, for example.

Six metres down, says Reeve, most 'stuff' isn't going anywhere.

However, the existence of pathways - transmission routes premised, say, on the risk of new water pipes cracking - also need to be factored in, but, not enough to get too hung up about it. There is, in good old engineering terms, enough contingency in the conceptual models and calculations to be able to sleep well at night.

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