Manteca has been effectively removing TCP from municipal well water over the past decade.

Described by the state as a “potent carcinogen”, it has been detected in a handful of city wells over the years as the plume of contamination spreads hundreds of feet below ground.

Most of the city’s wells aren’t impacted.

The effective removal of the containment TCP — 1,2,3-trichloropapne — from municipal water has been a priority for the city since it was first detected in a well in 2013.

The city last month finished a $3.96 million project that added the TCP treatment process to a well located in the park serving the Yosemite Village neighborhood south of Lincoln Center anchored by Hafer’s Furniture and to the southeast of the Union Road and Yosemite Avenue intersection.

Extremely small traces of the chemical TCP used in pesticides for orchard crops as well as in industrial solvents has been detected in several Manteca municipal water wells over the years.

The State of California mandatory reportable threshold is 5 parts per trillion while the federal Environmental and Protection Agency’s reporting threshold is 30 parts per trillion.

The first well TCP was detected in was in July 2013 in the Manteca Industrial Park along Vanderbilt Circle near Main Street and the 120 Bypass.

The well at the time had 38 parts per trillion of 1,2,3-TCP.   
To put that in perspective, 38 parts per trillion is the equivalent of 38 drops of water diluted into 20-Olympic-sized swimming pools.

Federal environmental laws do not require any action  to be taken unless the 1,2,3-TCP contamination reaches 500 parts per trillion or 13 times higher than what was detected July 2013.
That said, acting out of an abundance of caution in July 2017, the California State Water Resources Control Board Division of Drinking Water adopted a new, enforceable regulatory standard, called a Maximum Contaminant Level, for 1,2,3-trichloroporane (“TCP”), which the State describes as a “potent carcinogen” that “poses a significant carcinogenic risk when it occurs in drinking water” at low levels. 

 TCP has already been detected in hundreds of water wells in California.

Manteca is among more than 100 entities that have filed litigation over the years against Shell Oil and Dow Chemical that manufactured and sold products with TCP in them.

To contact Dennis Wyatt, email dwyatt@mantecabulletin.com