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Mind the gaps

GEOENVIRONMENTAL ENGINEERING

Geoenvironmental engineers are working hard to implement the CLEA model for assessing contaminated land. Gareth Beazant reports.

Replacement government guidelines on contaminated land contain some yawning gaps which at least one consultant is trying to fill.

Just before Christmas, the Department for Environment, Food and Rural Affairs withdrew Inter-Departmental Committee on the Redevelopment of Contaminated Land (ICRCL) guidance.

Its replacement was CLEA (Contaminated Land Exposure Assessment), which is aimed at providing 'the key instruments for generic assessment of the human health risks from land contamination.' But six months on, those involved in contaminated land are still getting to grips with the assessment model.

'The complete withdrawal of ICRCL 59/83 took many in the industry by surprise and has left uncertainty, ' explains Hyder Consulting geoenvironmental project manager George Flower.

'There are not enough numbers for commonly occurring contaminants to populate the CLEA model.

'Defra is working on filling the gaps, but we are faced with having to assess the risk without definitive guidelines on where toxicological numbers should come from, ' he says.

'We believe that Defra too has found it difficult to agree internally on acceptable toxicological values, and suspect that this has caused the delays on issuing the further guidance.' The key issues are the risk assessments associated with CLEA Soil Guideline Values (SGVs) that are calculated to protect humans against chronic, lifetime risks from single contaminants at the ground surface.

They do not consider human short-term acute risks or risks while at work. And they do not consider the effect of combinations of chemicals.

So far about 50 elements or compounds have been classed as dangerous to human health and the environment, but only seven SGVs have been calculated, plus another three tox reports (a collation of toxicological data and intake values for humans for the chemical element or compound).

This leaves consultants having to define a value from all available research, some of which is classified, old or hard to find.

And, because the data is provided by the consultant, different results will be encountered across the country.

'What we have decided to do to be consistent, is to come up with our own methodology to fill the gap based on our own research, ' explains Hyder Consulting technical director Eric Cooper.

'We started detailed research on toxicological data as soon as ICRCL was withdrawn and we are saying, 'this is how we will do it and if the environmental health officer says no, then we will change it'.

'But so far our experience with the regulator is that it is delighted to have some sort of clarity brought to bear in lieu of 'official' guidelines.' This research has opened up a can of worms in the available information on certain materials.

Some only have limited data available in the US or Holland, while some has been classed as confidential.

'It's hard. We cannot use numbers that are not really understood or lack industry consensus, ' says Flower.

'Most of our industry does not come from a biological background and you cannot learn it overnight. There is a chance that at Hyder we will be looking at employing someone with formal toxicology qualifications to help with this, and I am sure other consultants will do the same.' The issue could be the deciding factor in whether land is remediated and developed. If the cost proves too high because of lengthy and possibly 'over the top' remediation schemes, land could be left idle.

'There is a lot of inconsistency about what people are doing or what clients want, ' explains Cooper. 'There is some way to go; we're not saying the model is poor, far from it, we welcome CLEA and think it will be good for the sector. But the release of it before all the values was a bit a premature.' 'It does pose a question - with ICRCL withdrawn and local authorities saying it cannot be used, where does this leave the thousands of sites that were remediated under those guidelines?' Flower adds.

Land Condition Records

The time is right for a push on Land Condition Records according to one of the UK's leading Specialists in Land Conditions (SiLC).

Eric Cooper recently asked the Institute of Environmental Management and Assessment how many Land Condition Records (LCRs) had been produced since the official launch in November 2000.

The institute was set the task of maintaining the initiative aimed at standardising a system for reporting on brownfield land.

'We need to start knocking on doors to increase the number of LCRS carried out, ' explains Cooper.

'There is no large co-ordinated marketing campaign, possibly due to lack of funding, and people are using the same sort of land reports as before.'

LCRs started from a report by the Urban Task Force in 1999, Towards an Urban Renaissance . Among many issues it covered the uncertainty in buying, selling and developing brownfield land. It wanted a standardised system for reporting and the LCR was born.

It was then decided to have an independent accreditation system for land quality and contaminated land, and SiLC was launched. Despite the scheme taking off, the LCR has been slow to follow.

'The document is extremely thorough and asks every question about a piece of land, ' says Cooper.

'There is a great attention to detail which is crucial. In brownfield land if you miss a tiny bit of information it could prove very costly.'

An LCR is a comprehensive document that addresses all land quality issues. It comes in a standard format with an executive summary to provide an overall picture of the land. This can be used as a stand-alone document for individual homeowners on a large residential development.

'It says factually what has been done to the land and puts all the information in one place. It links the clients and consultants to commercial and legal teams so everyone gets the same document, the same information, ' Cooper explains.

Hyder Consulting geoenvironmental project manager George Flower says:

'There is a lot less paper, it is like a passport and similar to CDM documents in that they will stay with the building for life.'

LCRs can be downloaded free of charge from the internet and now the aim is to increase their use.

'There is a selling job to do, ' says Cooper. 'There will be a meeting of all SiLCs to look at ways to approach it. At Hyder we think it is a very good idea. It is providing good practice, standards and quality. LCRs will put a marker down and raise levels.'

LCRs have to be signed off by an SiLC. To make an application to become a SiLC you need a minimum of eight years' experience with the right degree and be a chartered member of a relevant institution. Then there is an exam and an interview. There are about 30 people in the country who can use the letters after their name.

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