Millions of euro will have to be spent containing and monitoring the Republic's illegally-dumped waste for at least a generation if the more expensive option of excavation is to be avoided.
That is the opinion of Swiss experts and it is the message they delivered to an Irish delegation which visited Switzerland recently.
The Swiss are currently digging up and incinerating hazardous waste from a number of sites - most notably at Kolliken, between Basel and Zurich, where a 250,000 cubic metre dump is being remediated at a cost of €350million (500 million Swiss francs).
According to Dr Mathais Tellenbach, policy director of the Swiss Agency for Environment, Forests and Landscapes (SAEFL), the standard procedure applied to potentially volatile dumps is to "excavate, classify and treat".
In circumstances where it is known which pollutants are contained in a landfill, it may be possible to contain and monitor them "for at least a generation, possibly two, but even then it may be necessary to excavate", he said.
Dr Tellenbach is familiar with the Republic's experience of illegally-dumped materials and last year was a guest speaker at an environmental conference in Co Louth. He warned then that long-term containment and monitoring were only applicable "when you know what is there, when what is in the ground is recorded".
While most of the waste identified in the Republic's illegal dumps in recent months has been domestic material, hazardous elements have included hospital waste, the chemical methylene chloride, printers' inks, and oils. Chemical contamination has been identified at sites in Louth, Dublin, Galway and Waterford among others.
Yet another difficulty faced by the Irish authorities is the lack of a national contaminated sites register, a "first step" in the remediation process, according to the Swiss.
Since compiling a national register of such sites, the Swiss have identified upwards of 40,000 "polluted" sites, about 3,000 of which they have classified as "contaminated".
At Kolliken, the waste was buried over a seven-year period from 1978 to 1985, netting revenues of about €8 million (12 million Swiss francs). However, following complaints, it was found that the groundwater was polluted, and more than €100 million has so far been spent on building underground barriers and a tunnel to capture and divert the leachate.
The waste will be removed and the site completely remediated by 2015. "It was an expensive lesson", the Kolliken project manager, Mr Joseph Hochreuter, told the Irish delegation.
However, because the Swiss have records of what is contained in dumps, SAEFL calculates that most of the domestic refuse sites can be remediated at a cost of less than 1 million Swiss francs, with ongoing costs for monitoring.
On the plus side for the Republic, the director-general of the Irish Environmental Protection Agency, Dr Mary Kelly, who was a member of the expert group which visited Switzerland, said that we do not have the heavy industrial background that the Swiss have. Consequently, any chemicals and hazardous wastes buried here would not be even close to the levels present in the Swiss dumps.
Another plus for Ireland is that disused gravel pits can provide natural linings which contain leachate, thus making excavation and incineration unnecessary.
In other cases, where the waste is domestic, it may be possible to dig up the material, line the dump and put the waste back.
With many of the Republic's illegal dumps based in gravel pits, it may be possible that the cheaper option - that of containment and monitoring - is an acceptable way to proceed.
However, according to Dr Tellenbach, the Republic's chief difficulty is that what is in the ground in illegal dumps is largely unknown, which makes a decision on whether to excavate and incinerate, or to contain and monitor, difficult. "Neither option is cheap", he said.