If one owns a contaminated site that is ripe for development, it is not usually to one’s advantage to wait for the public authorities to remediate it. That can take a very long time. The public authorities prioritize remediation of those sites that pose an immediate health hazard to the present inhabitants, as well as those that pose a threat to an exploitable groundwater resource.
The majority of owners therefore make the calculation: Will the development project turn a profit even if remediation costs have to be included in the budget? If the answer is yes, then it can pay to remediate the site. For this reason hundreds of contamination investigations are undertaken each year by engineering consultancy firms in connection with property sales or construction projects.
If the result of the preliminary investigation is reasonably satisfactory, then the private developer can proceed and draw up a remediation project. However, the project has to be approved by the County before excavation work starts.
During the period 1990-93, just over 400 contaminated sites had been voluntarily remediated. The cost of these projects is unknown, but assuming an average of DKK 1.5 million then the total investment would have been around DKK 600 million.
The remediation of contaminated defence sites to be undertaken by the Ministry of Defence in coming years will also follow the rules for voluntary remediation. In some cases remediation will be undertaken in order to provide clean plots for development, in other cases to protect the groundwater.
10.3.2. Criteria:
During the first many years - from 1983 to around 1990 - the Danish EPA insisted that every single contaminated site case should be processed individually, and would not set general limits (requirements) as to when land should be considered as being contaminated. This was unsatisfactory for the private developers because it made it difficult for them to delimit and cost voluntary remediation projects. Neither was it acceptable for the Counties, and they therefore started to lay down requirements themselves. It was also an impossible situation for the enterprises that wanted to undertake the remediation work as they did not know to what standard they had to clean up.
In recent years, however, the Danish EPA has attempted to meet the need for requirements. Of greatest significance are the requirements concerning soil polluted with petrol/gas oil, where the soil must be cleaned down to 25 mg hydrocarbon per kg for petrol and 50 mg/kg for gas oil. These limits were selected out of concideration for groundwater protection and for contact with the soil during use of the site. In consideration of the latter, the PAH content shall be less than 5 mg/kg.
Requirements are also stipulated as to the heavy metals content of the soil, e.g. chromium (total) 100 mg/kg soil, arsenic 20 mg/kg and lead 40 mg/kg. These levels have been set on the basis of a knowledge of their evaporation, working environment conditions during excavation work and contact with the soil by children.
Requirements have also been set as to the content of a number of
substances in the groundwater under contaminated land. For example, the benzene content
must not exceed 0.3 µg/l, the total hydrocarbon content must not exceed 10 µg/l, and the
trichloroethylene content must not exceed 1 µg/l. Requirements still differ from county
to county, however, and the press has drawn attention to examples of soil having become
"clean" simply by being transported to another county. In my opinion
contaminated soil is a glaring example of an area where there is a marked need for uniform
nationwide requirements.