In January 1980 the Massachusetts Department of Environmental Quality Engineering (now Massachusetts Department of Environmental Protection (MassDEP)) and the other five New England States discovered a problem with the chemical tetrachloroethylene (PCE) leaching into some of their drinking water because of the type of pipe used in some parts of the water distribution system. Tetrachloroethylene is an organic chemical slightly soluble in water used in a variety of ways including the dry cleaning process, as a degreasing solvent, and heat transfer medium. The source of the contamination proved to be vinyl-lined asbestos cement water mains. The PCE had been used by the pipe manufacturer as a solvent for the vinyl resin liner. In the coating process, the solution had been sprayed onto the interior walls of the pipe and allowed to dry. In some cases traces of the solvent remained in the resin lining or in the pores of the pipe walls up to the time the pipes were installed as water mains.
Asbestos cement (AC) pipes have been in use since the 1930's. The lined variety had been in use for approximately twelve years in New England. The vinyl lining reportedly was developed as a response to customer complaints about the taste and odor of water coming into contact with the asphaltic coating used on water supply pipes, especially in dead end situations.
An extensive survey revealed that 660 miles of the pipe were used as water mains in Massachusetts with 91 different communities involved. The area most seriously impacted fell under the jurisdiction of MassDEP southeast region. Cities and towns within that area accounted for approximately 500 miles of the pipe, with 44 different communities contributing to the figure. As a result of this discovery public water systems throughout Massachusetts, having known quantities of VLAC pipe, began monitoring for PCE. Nineteen years later, many miles of VLAC pipe have been removed but PCE is still detected in approximately 30 percent of distribution samples with a few sites requiring mitigation to reduce levels below the 0.005 mg/l maximum contaminant level (MCL).
The information provided in this summary is a comparison between historical MassDEP data compiled in 1992 and information received from public water systems (PWS) as a result of the VLAC Pipe Survey that was mailed on December 26, 2008.
PWSs that received the 2009 Vinyl-Lined Asbestos Cement (VLAC) Pipe Survey were those that have tetrachloroethylene listed on their current "Required Water Quality Sampling Schedule". PWSs were asked to provide an estimate of the total length of VLAC pipe (in miles) remaining in their system.
As a result of this survey, MassDEP has determined that since 1992 close to 100 miles of VLAC pipe has been removed from the ground, which is a reduction of 15% of the total amount of VLAC pipe remaining in use today. In addition to the removal of 15% of VLAC pipe, numerous PWSs have looped sections of their system which has increased the volume of water flowing through these pipes, thereby decreasing or totally eliminating the detection of PCE during routine scheduled monitoring.
The MassDEP Drinking Water Program Guide for VLAC pipe monitoring was updated in May 2006 [Vinyl-Lined Asbestos-Cement Pipe (VLAC) Monitoring Program Guide for Tetrachloroethylene, a/k/a Perchloroethylene (PCE). This is an effort to assist MassDEP in determining when sampling for PCE can be reduced or eliminated. MassDEP recognizes that existing sample schedules for PCE may not reflect current pipe conditions. PWSs are encouraged to review the updates to the VLAC Monitoring Program Guide as it may affect your PWS.