The PCE Migraine

I am often told by real estate owners that they have a “dry cleaner headache”. Dry cleaners can easily become a real estate headache for a real estate owner and often, can develop into a real migraine.   What is this headache?  The headache I am referring is caused by a carcinogenic chemical known as PCE. PCE or tetrachloroethene (also known by at least 40 other names), is primarily used in dry cleaning. Such operations can result in a release of PCE at the site with entry to soil beneath the building.     So what specifically is the issue, the migraine associated with a PCE release?  It consists of two parts. Firstly, the potential for exposure of PCE vapor to occupants of the building, and secondly the possibility of PCE entering water beneath the site and therefore impacting local drinking water.    What is the best method to address a PCE release? Find an experienced PCE doctor: an experienced consultant with a background in all aspects of PCE characteristics, release scenarios, migration properties, cost-effective cleanup options and applications, and experience working with regulatory agencies and providing litigation support and expert witness testimony.   In upcoming blogs, I will take a look at how PCE can become a migraine to a real estate holder, what to do to diagnose and analyze the problem, and remedies to address the release in a timely and cost effective manner.   What is PCE and what’s an important persistent PCE release? PCE was first formulated in 1821. It is a double-bonded carbon structure with four chlorines. PCE is a colorless liquid that has been used in dry cleaning since the late 1930s, replacing synthetic solvents like carbon tetrachloride, with PCE demand increasing through 1981.    In 1990, of the total amount of PCE used, 50% was used for dry cleaning, 25% in chemical manufacturing, 15% in metal cleaning/degreasing and the remainder 10% for miscellaneous uses. In the mid 1990s, PCE use in dry cleaning declined primarily due to the introduction of machines with closed loop systems. Prior to this time, 30% of the units were a transfer machine and 70% a dry-to-dry vented machine. In the transfer machine, clothing is washed in one unit and transferred to another for drying, with emissions either uncontrolled or routed to a control device. In the dry-to-dry closed loop machine, the wash and dry cycles are in the same unit with PCE either uncontrolled or vented to a control device. The probability of a PCE release from the earlier units is significantly higher than from the later, closed loop system.   A Persistent PCE Release   An important persistent PCE release with respect to the environment is one that finds its way to soil beneath the building.  Once beneath the building, PCE will volatilize into the voids between soil particles and migrate horizontally and vertically, creating a PCE cloud or plume. Horizontal migration spreads the PCE, making the plume larger.    Vertical upward migration probably will result in vapors entering a building and vertical downward migration will probably result in making the plume larger and a possible contribution to contamination of groundwater. This kind of migration is known as Vapor Intrusion. For simplicity, I have divided PCE releases to soil into a small release, medium release and large release based on my experience: