Jim Steinberg – Staff Writer, The Sun
BARSTOW – Mention the community of Hinkley and one might think of a chromium plume in the area. That association might only be about half right. Get ready to add a new one: Manganese plume.
Since November, San Francisco-based Pacific Gas & Electric Co. has been remediating a small manganese plume north of the ground zero point of its internationally known chromium 6 plume.
And later this year, it will begin sampling multiple points to the west, as tests at several private wells have shown high amounts of manganese and black water – a telltale sign that manganese is present, said Lauri Kemper assistant executive officer of the Lahontan Regional Water Quality Control Board, during an update for the agency’s board of directors at a public meeting in Barstow on Wednesday.
Because Hinkley’s plume of cancer-causing chromium 6 is moving northward, it would seem logical that the source of the manganese to the west must be coming from another source, said Ian Webster, the scientific advisor for a group of Hinkley residents.
“But why is this happening now?” he asked.
The Lahontan water board asked PG&E to map the manganese plume.
The addition of manganese, a heavy metal-like chromium, to Hinkley’s groundwater was an expected byproduct from the injection of ethanol into the ground where the highest concentration of chromium 6 is found.
The ethanol sets up a chemical reaction, which changes chromium 6 to the relatively harmless chromium 3.
The ground zero site is where, in the 1950s and 1960s PG&E dumped chromium 6 laced water from a cooling tower at its Hinkley natural gas pumping station.
This is where chromium concentrations were the highest and the injection of ethanol has brought the concentration levels down.
But this new manganese plume poses its own set of health hazards, most of them neurological. Manganese has been associated with mental impairment. It may play a role in the development of certain Alzheimer’s and Parkinson’s illnesses, health officials say.
The amount of magnesium unleashed from the soil and now in some of Hinkley’s groundwater has exceeded expectations of some water scientists and upset many in Hinkley, many of whom thought the chromium 6 problem was more than enough to deal with.
Increasingly blackish water – a signature of manganese – is being found in private wells located some distance away from ground zero.
U.S. Geological Survey research hydrologist John Izbicki said, in an interview here Wednesday night, said he will be assisting in future studies to determine if the manganese showing up in residents’ water is related to the injection of ethanol or happening for some other reason.
Izbicki said he has been involved in the study of underground water movement in the Mojave Desert since 1990.
Izbicki will also become involved in a study to determine the true size of the chromium 6 plume and the study to determine what was the natural concentration of chromium 6 in Hinkley’s water before PG&E introduced this chemical into the water supply.
Ian Webster, a scientist advising a committee of Hinkley residents, said Izbicki will provide needed expertise and will bring “new tools and a new way of looking at things” as research moves forward to answer questions about Hinkley’s underground water contamination.
Over the objection of some Hinkley residents, the water board Wednesday night approved a request by PG&E to build new evaporation ponds for cooling tower water discharge from its Hinkley operations.
This water will have no chromium 6, water agency officials said.
And while the original ponds were were unlined, these new ponds have three layers of lining, have sensors to detect leaks and are large enough to capture water runoff from a 1,000 year rainstorm, said Brianna Bergen, an engineering geologist with the Lahontan water agency.