How Clean is Clean?

When deciding on a remediation strategy for a site which is contaminated, the strategy should have a clearly defined end goal. What is the final result that we strive to attain?

Defining contamination

There are a number of attributes which are necessary to accurately define the extent of contamination on a site. These include the spatial dimensions of the contamination (how wide and how deep is the contamination) and the concentration of the contamination at each point within that zone. Some other factors that also need to be considered are the presence of ground water, its depth and the variance in the level of that ground water during times of high precipitation and dry periods. One should also take into account what the land is or will be used for, what structures are present, and what the neighbouring land uses are.

Target Remediation Levels

A competent environmental contractor, once having determined the full extent of the contamination, should be able to engineer a remediation solution to bring the level of contamination down to or below a certain target remediation level. It is the determination of this target remediation level that is key. Stakeholders need to be aware of what standard of remediation they are:

(i) Obligated to achieve by law
(ii) Entitled to in law

In relation to (i) for example, for groundwater there is little national guidance available regarding what is an acceptable standard. In the United Kingdom and Ireland, a stakeholder would normally have to fall back to the requirements as set out by the EU Water Framework Directive 2000/60/EC and the World Health Organisation Guidelines for Drinking Water Quality which mandates a maximum level of contamination of 1ppb.

In relation to (ii) above, this varies by circumstance and jurisdiction.

In Ireland, if the incident is being indemnified by an insurer, the insurer is obligated by the Consumer Protection Code 2012 (section 7.14[b]) to restore the property to at least the standard that existed prior to the insured event.

In Ireland and the United Kingdom, if the pollution is caused by a third party, a stakeholder is entitled in common law to be put back in the position they were in prior to the incident occurring. This effectively means, no contamination or as near as possible to this as can be achieved.

In the United Kingdom, if the contamination is caused by a stakeholder and is being indemnified under the terms of the stakeholder’s own insurance policy, then it is down to the terms of that policy what level of remediation is appropriate. Generally, insurance policies do not get involved with this level of detail and in absence of any specific reference, a policyholder should be entitled to an indemnity to pre-loss condition which effectively means, no contamination or as near as possible to this as can be achieved.


The Environment Agency of England and Wales produced a document in December 2004 called “Model Procedures for the Management of Land Contamination – Contaminated Land Report 11” (CLR11). This is an extremely comprehensive set of guidelines setting out a framework for the remediation of land.

Various sets of best practice procedures for land surveying and remediation are outlined. These include for example sampling strategies, mapping strategies and target remediation methodologies. Remediation standards set out in CLR11 generally advocate a risk-based approach to remediation. This approach advocates the determination of risks to people and the environment caused by the contamination and taking the appropriate remediation measures to reduce that risk. This more often than not does not mean removing all the contamination.

It must be noted, however, that CLR11 does not apply to every type of contaminated site. For example, for residential land use, it is not relevant at all. What is more, CLR11 is only a set of guidelines and has no statutory basis in law. We often see contractors improperly applying CLR11 for projects and representing to stakeholders that such use is apropriate. This is often done for economic reasons as the remediation of a site utilising a risk-based approach generally tends to be much less expensive than a remediation approach designed to remove the contamination entirely (or as near as possible to this as possible).

Costs and remediation standards

The choice of the target remediation standard can have a great bearing on the cost of the works. The variance can be large, even orders of magnitude greater for a pristine remediation in comparison to a risk-based remediation.

By way of example, we recently were involved in a site in the United Kingdom whereby land was contaminated by the negligent activities of a fuel delivery company filling a storage tank which was not connected to any heating system. The kerosene escaped from the tank and caused extensive damage to structures and property that was on the site. As the contamination was caused by a third party’s negligence, we were able to advise the property owners of their entitlement to have their property restored to its pre-incident condition. The polluter’s insurer, however, strove for a risk-based approach which would have superficially remediated the site but left considerable contamination at depth and low levels of contamination at the shallower horizons on site. Following legal action, the pristine remediation approach won out at a cost of £200,000. This is in comparison to a suggested figure by the polluter of £60,000 for the risk-based approach.

Clearly, there are significant cost savings to be achieved by adopting a risk-based remediation approach to remediation. Stakeholder’s need to be advised however that if they are entitled to a higher standard of remediation then this is done and not hidden from them for economic reasons.

Future problems of risk-based approaches

In the event that a risk-based approach is adopted on a site for the remediation of contamination, the stakeholders may have future issues or obligations regarding the site. This is mainly due to contamination being left following the remediation.

For example

(i) If the property owner wishes to dispose of/sell the property they have an obligation to disclose to the potential new owner prior to the sale that there had been a contamination incident on the site and that residual contamination remains. This could at worst scupper the sale or cause a reduction in value (diminution).
(ii) Future work on the site could cause residual contamination to manifest itself again. For example, if a property were to be extended or altered, future groundworks could expose contamination again to receptors (people or the environment). This could necessitate further works potentially at significant cost. In other words, future actions on the site may be affected or curtailed by a risk-based approach.
(iii) Public awareness that a property was contaminated and that some of that contaminated material was still present may cause blight issues. For example, if the property was a school, parents may be unhappy sending their children there, or if it was a domestic dwelling, purchasers may be put off if the property ever came on the market.
(iv) The future standard of what is deemed an acceptable risk may change. If a criterion was set at the time of the risk-based remediation of a certain threshold for a contaminant, there is the possibility that that threshold could change in the future. For example, in hydrocarbon (oil) contamination, if future scientific work determined that a particular fraction in kerosene was carcinogenic, then this may necessitate more remediation works. One needs to know that should such an eventuality unfold, who will be responsible for payment for the further works.


In summary, there are two main standards for the remediation of contaminated sites. These are:

Both approaches have their uses and are used in industry, but care should be taken that the appropriate and fair methodology is adopted.

Stakeholders should be aware of their entitlements and their legal obligations. Paymasters should not take advantage of the lack of knowledge of a stakeholder and advocate a remediation approach which is less than this, particularly for economic reasons.