Source: San Bernardino County Sun (CA), February 10, 2014
Posted on: http://envfpn.advisen.com
Pacific Gas and Electric Co. is offering some residents north of this High Desert community a free water purification system until more is understood about the nature of their pollution.
Officially, Hinkley’s plume of cancer-causing chromium-6 is now eight miles long, from north to south, traversing the Hinkley Gap and approaching the Harper dry lake.
But PG&E and its consultants believe that the chromium-6 in this area is naturally occurring and not the result of their operations.
State regulators, the Hinkley community and PG&E have agreed to support a four-year study by U.S. Geological Survey scientist John Izbicki to determine what part of the chromium-6 found in Hinkley’s groundwater belongs to PG&E and what part was put there by nature.
In the 1950s and 1960s, PG&E used chromium-6, also known as hexavalent chromium, to prevent rust and algae buildup in cooling towers at its Hinkley natural gas compressor station.
The chemical, widely used before its cancer-causing properties were known, was discharged into unlined ponds and from there entered groundwater.
Based on property records and field surveys, PG&E estimates that an additional 15 to 20 homes might be involved in the sparsely populated area where PG&E plans to offer reverse osmosis purification units, Kevin Sullivan, the PG&E environmental engineer in charge of the Hinkley cleanup, wrote in a letter to Lauri Kemper, assistant executive officer for the Lahontan Regional Water Quality Control Board.
Of the 368 Hinkley residents who in June 2012 were offered either free whole house water filtration systems or property purchase, less than 40 opted for filtration, while 263 chose property purchase, according to Lahontan water board records.
Hinkley residents who opted for water filtration were given an expensive, resin-based filtration system outside their house and a reverse osmosis system under a sink or two inside the house.
In an interview, Kemper said the underground water in the extreme northern boundary of the plume is very high in naturally occurring salts and other chemicals that would quickly overwhelm the resin.
In his letter, Sullivan noted that the reverse osmosis system PG&E is proposing to use is very effective in removing chloride, iron, manganese, arsenic and uranium from water, as well as chromium-6.
Kemper said Friday that the Lahontan staff may reach a decision about the PG&E’s proposal this week.
All of the readings in this northern area were below the proposed new standard for chromium-6 in drinking water, which is 10 parts per billion, Kemper said.
Last year, the state Department of Public Health, after much study, proposed that the safe threshold for chromium-6 in drinking water be lowered from 50 parts per billion to 10 parts per billion.
Public health officials are reviewing comments, made during public hearings or sent to them, on that new threshold and have been ordered by a state judge to finalize their decision before June 1.
The federal “safe level” for chromium-6 in drinking water is 100 parts per billion.