South Pasadena took a major step towards renewing its groundwater as a clean source of drinking water early this month when it installed four new granular activated carbon (GAC) filtration tanks at Wilson Reservoir in San Gabriel.
The tanks will reduce contaminant levels of the carcinogen 1,2,3-Trichloropropane (1,2,3-TCP) to below the 5 parts per trillion maximum contaminant level established by the state in January.
That regulation, which city officials say was hurriedly put into effect, forced the city to significantly limit use of its groundwater and borrow surface water from the Metropolitan Water District. The city has been scrambling to respond to the regulation’s unintended consequences since its passage.
While installing GAC tanks was always the city’s long-term plan for treating its groundwater supply, the process had to be dramatically accelerated after alarming reports of water discoloration in the homes of South Pasadena residents began to be phoned in to City Hall in late March.
City officials in the Public Works and Water Divisions have now received more than 200 complaints from residents reporting “brown,” “yellow,” and “odorous” water in their homes. Water Operations Manager Anteneh Tesfaye says it is his staff’s belief that the number of affected residents is higher.
An investigation led by Tesfaye, with the help of expert consultants, led to the conclusion that the unusually large influx of MWD surface water was reacting with galvanized piping in homes and causing high amounts of iron to appear in the water. The iron, the investigation concluded, was the chemical culprit for the discoloration.
“The issue, we believe, is that the city’s galvanized pipes were not acclimated for the quantity of surface water the regulation forced us to use,” Tesfaye said during an unveiling of the GAC tanks on Oct. 3. “Initially, when we were forced to find another groundwater source, we felt lucky to have the MWD water. We have been using their water on and off since the 1970s, and never encountered this problem prior to this year.”
Two of the four GAC tanks are permanent, while the other two are temporary and will be replaced with permanent tanks sometime in January. There will be eight tanks in total at Wilson Reservoir at the completion of the project, which will cost about $2.7 million, according to South Pasadena’s public information officer, John Pope.
The temporary system will be put into use shortly, once the Department of Drinking Water grants formal approval.
“Operational testing (began last week), with DDW Staff on site to witness testing in order to issue an operational permit for the temporary system,” Pope informed The Review last week. “The approval is required by the DDW to begin operations. If all goes well with the DDW and permit approval, we hope to be up and running by (this) week.”