By Baker & McKenzie

Soil remediation in Mexico has traditionally been a chaotic sigue due to a lack of remediation criteria in national law. Responding to the usual question of "how clean is clean?" has proven to be at times impossible, even if some basic guidelines have been provided since 1988 by the General Law of Environmental

Balance and Protection (the "General Law") and its regulations on hazardous waste.

Those guidelines -specified in the amendments to the General Law in 1996- attended to a land use criteria, but without any detailed allowed quantities of pollutants it was very difficult to determine precisely how clean the soil had to be to develop activities suitable for the authorized use of the property. The Mexican Federal Bureau of Environmental Protection ("PROFEPA") sometimes used criteria from the U.S. Environmental Protection Agency, without any proper foundation in Mexican Law, which resulted in a lack of legal certainty.

The need for national quantification criteria led to the enactment of Emergency Official Mexican Standard (the "Emergency Standard") that was in force between August 21, 2002 and August 20, 2003. This was due to the fact that emergency norms, following the provisions of the Law of Measurements and Standardization, may only be in force for 6 months and extended only once for another equal term.

On March 29, 2005, Official Mexican Standard NOM-138-SEMARNAT/SS-2003 ("NOM-138") entitled "Maximum allowable limits of hydrocarbons in soil and specifications for its characterization and remediation" was published in the Official Federal Gazette, and will enter in force 60 days after its publication.

NOM-138 differs from the former emergency one in some aspects. It is less stringent with regard to maximum allowable limits for certain substances, and establishes new methods of analysis. It also contemplates some restrictions with regard to remediation (i.e. remediation by genetically modified microorganisms1) that were absent in the Emergency Standard.

With the enactment of NOM-138, the provisions of the General Law for the Prevention and Integral Management of Waste ("Waste Law") regarding liability for pollution and remediation may actually be implemented properly, at least with regard to soil pollution caused by the hydrocarbons specified in NOM-138.

The Waste Law establishes liability provisions for polluters and hazardous waste service providers, as well as other requirements connected to activities regarding polluted properties (i.e. it requires that in case of any transaction of properties with hazardous waste pollution, authorization is required from the environmental authorities).

Nevertheless, without any specific criteria it was very hard to implement such provisions. As soon as NOM-138 enters in force, the environmental authorities are very likely to increase the enforcement of environmental laws dealing with soil pollution caused by hydrocarbons.

Several questions may be raised when implementing NOM-138. What will happen with properties sold prior to it entering into force, if such standard was not met? Will there be liability from the seller, even if he performed a site remediation to the satisfaction of environmental authorities? What about the liability of the buyer? Will he have any cleanup liability?