On September 10, 2013, the Ministry of Environment and Natural Resources published in the Official Federal Gazette Mexican Official Standard NOM-138-SEMARNAT/SSA1-2012 (“NOM-138-2012”) that establishes the maximum allowable limits for hydrocarbons in soils, as well the guidelines for their sampling in characterization studies and applicable specifications for soil remediation.

NOM-138-2012 substitutes standard NOM-138-SEMARNAT/SS-2003 (“NOM-138-2003”) that has been in force since September 29, 2005.

Even though the maximum allowable limits established by NOM-138-2012 for hydrocarbons in soils are the same ones contained in NOM-138-2003, the heavy fraction hydrocarbon parameter has been modified. Under the previous standard, the molecular weight to determine a heavy fraction hydrocarbon would have to exceed C18. With this new standard, it is required that molecules contain between 28-40 carbon atoms (C28-C40) to be considered heavy fraction.

Also, there are additional requirements for sampling plans and the section contained in NOM-138-2003 that made reference to the characterization study has been eliminated, because the specifications regarding such study are now contained in the Regulations to the General Law for the Prevention and Integral Management of Waste, which came into force after the enactment of NOM-138-2003.

NOM-138-2012 will become effective on December 5th  2013.