In Scituate, some water mains, or large, subsurface pipes that distribute water throughout town, are lined with a vinyl plastic material. These pipes are called vinyl lined asbestos cement (VLAC) piping. In the late 1960s, VLAC piping was developed because conventional asbestos cement pipes were found to produce poor tasting water. In the late
1970s, it was discovered that VLAC pipe was capable of leaching tetrachloroethylene (PCE) into the water carried by the pipes (MDPH 1997b). This problem is more pronounced in pipes that are flushed infrequently (e.g., dead-end or low flow pipes). Although the manufacture of VLAC pipes ceased in 1980, by this time, approximately 660 miles of VLAC pipes had been installed in Massachusetts (Larsen et al 1983).
In 1980, the Massachusetts Department of Environmental Quality Engineering (now the MDEP) made recommendations to public water suppliers in Massachusetts about how to control PCE concentrations in VLAC pipes (DEQE 1980). The most effective, but most expensive, solution to the problem was to replace the VLAC pipes entirely. If replacement was not possible, a number of other measures could be implemented including installing
bleeders on dead-end pipes to increase water flow and looping dead-end water mains. In addition to these measures, the MDEP recommended, and then required, that all dead-end and low-flow areas served by VLAC pipes be tested for PCE to monitor the effectiveness of the remedial measures at keeping PCE concentrations below drinking water guidelines or standards (DEQE 1980, DEQE 1989)
VLAC water mains serve thirty areas in Scituate. Historically, these water mains were sampled at different times during some or all of the following years: 1980, 1983, 1985, and
1989. Review of available documents indicate that PCE was detected at concentrations exceeding the MMCL for PCE (5 ppb) in 15 out of the 30 locations sampled during this time period (SWD 1989). Table 2 shows the 15 locations where PCE was detected above the drinking water standard, as well as the years each location was sampled. PCE was not detected above the drinking water standard in water mains sampled in the Third Cliff area. In general, the highest concentrations of PCE were detected during the earlier years 1980 and
1985. In 1980, PCE was detected above the MCL in eight of the 15 locations sampled. The highest concentrations were detected on Turner Road (located in CT 5101.01) and Booth Hill Road (located in CT 5101.02) (Refer to Figure 3). PCE was detected in the water main located on Turner Road at a maximum concentration of 205 ppb, above the MCL of 5 ppb. PCE was also detected in the water main located on Booth Hill Road at a maximum concentration of 2,271 ppb (SWD 1989, 2000). Most of these 15 areas were serviced by dead-end water mains.
Concentrations of PCE tended to decrease with each year of sampling. In May 1980, the concentration of PCE in the water main located on Turner Road was 205 ppb. In December
1980, the concentration of PCE in this water main was 3.8 ppb. In August 1985, the concentration of PCE in this same main was 1.4 ppb. Similarly, the water main on Booth Hill Road contained 2,271 ppb of PCE in May 1980 with subsequent sampling of this water main in December 1980, November 1981, and August 1985 reveling PCE concentrations of
10, 11, and 10 ppb, respectively (SWD 1989).
During the later year of sampling (1989), three of the 12 locations sampled were found to contain PCE at concentrations above drinking water standards. These locations were the water main at Oceanside Drive, the Sanitary Landfill, and the Montessori School. The water main at Oceanside Drive, however, is not connected to any residences, businesses, or other establishments, therefore no one is exposed to this water. In addition, the water main at the Sanitary Landfill is used only to supply a lavatory and a fire hydrant; employees are supplied bottled water for drinking, thus limiting the potential for exposure to this water. The water main at the Montessori School is privately owned, and is not part of the municipal water system. According to the Scituate Water Division, the school was notified and advised of the PCE problem in this area (SWD 1989).
More recent sampling of nine of these locations was conducted in September 1999. PCE was detected at only two locations: Booth Hill Road and Conservation Way. The concentrations of PCE detected at these locations were below drinking water standards (SWD 2000).