Glycols are polyhydric alcohols, that is, aliphatic compounds with two or more hydroxyl (-OH) groups per molecule. Glycols have a wide range of uses including chemical feedstocks, solvents, and antifreeze. In addition, glycols are used in the dehydration of natural gas streams. Water in natural gas can cause operational problems in the transmission and processing of the gas (Sorensen et al., 2000), and thus gas dehydration units are ubiquitous at gas well sites and processing facilities. The most common dehydrating process used in the gas industry is the glycol absorption/stripping process (Katz and Lee, 1990). It is estimated that about 100,000 glycol dehydrating units exist worldwide (Grizzle, 1993).
The three glycols originally considered for soil and groundwater remediation guideline development were diethylene glycol (DEG), triethylene glycol (TEG), and tetraethylene glycol (TREG), which are formed by creating ether linkages between 2, 3, and 4 units of ethylene glycol (EG), respectively. All three compounds have been used in glycol dehydration units. However, due to the lack of published toxicological information on TREG, and the fact that the use of this compound in glycol dehydration units is uncommon, only DEG and TEG were carried forward to the guideline development stage. The limited background data that were found concerning TREG are retained in this document for completeness.
For convenience, DEG, TEG, and TREG are collectively referred to in this document as “the Glycols”. No soil or groundwater remediation guidelines have been published to date for any of the Glycols by either Alberta Environment (AENV) or the Canadian Council of Ministers of the Environment (CCME). This document develops proposed soil and groundwater remediation guidelines for DEG and TEG consistent with the Alberta Environment (AENV, 2007a) framework.