U.S. Geological Survey hydrologist to research natural levels of chromium 6
By Brooke Self – DesertDispatch.com, Staff Writer
HINKLEY • A new background study to determine the naturally occurring level of hexavalent chromium, or chromium 6, found in the Hinkley valley has been commissioned by Pacific Gas and Electric and the regional water board overseeing the groundwater clean-up.
Dr. John Izbicki, a hydrologist with the U.S. Geological Survey, will begin studying the groundwater conditions in Hinkley with the latest technology available, according to PG&E principal remediation specialist Danielle Starring.
Izbicki is expected to be an objective expert in the contamination case and has been approved by PG&E, the Lahontan Regional Water Board and local residents on the Community Advisory Committee, she said.
PG&E was responsible for contaminating the groundwater in Hinkley in the 1950s and 60s near the company’s compressor station on Community Boulevard. Industrial waste containing hexavalent chromium was discharged into unlined ponds near the facility.
Lahontan assistant executive officer, Lauri Kemper, said previously that the new background study is being funded by PG&E though the water board will oversee the contract with the U.S. Geological Survey.
“It’s going to take a couple of years,” Starring said. “It’s a long process; but the idea is to answer the most pressing questions first.”
Those questions encompass whether the origins of chromium 6 in certain areas of Hinkley were caused by PG&E’s contamination, unique changes to water chemistry, or are naturally occurring, she said. Because Hinkley is located among the Mojave Desert the terrain comprises diverse geological conditions, she said, which could also impact the level of chromium 6 found throughout the valley. Izbicki will research all of those possibilities using newer technology than what was available at the time of the original background study, she said.
The previous background study conducted in 2007 determined the average background level of chromium 6 in Hinkley to be between 0 and 1.2 ppb, Kemper said. PG&E has been ordered to clean up the plume area to a maximum level of 3.1 ppb because statistically the range could also naturally reach that level, she said. PG&E spokesman Jeff Smith said no matter what the new background number is determined to be, the company will in the interim continue their clean-up efforts to the 3.1 ppb number. And reverting the groundwater of the miles-wide plume is expected to take another 30 to 40 years, he said.
Starring said part of Izbicki’s new research will be studying isotopes in the groundwater to determine the age of the water and its historical uses. In Hinkley’s past, dozens of acres in the area contained alfalfa farms owned by local residents. At least three dairy farms still operate in the community.
A recent investigative order issued by Lahontan also tasked the company to look into the causes of a possible western expansion of the plume. After data gathered from monitoring wells in the first quarter of 2013 was released the plume map was updated to add Hinkley School, the Hinkley Market and Hinkley Bible Church among properties located within a 1-mile radius of the plume. PG&E calls the new boundary to the west, the “western finger,” where a thin stretch of the plume map has been redrawn to introduce the one monitoring well that tested at 4.2 ppb of chromium 6. That well is directly west of a line of five fresh water injection pumps that are in place to contain the plume’s groundwater at the western boundary. Fresh water injections make up one-third of PG&E’s clean-up efforts.
“We feel we have the data to show plume containment and we’re committed to cleaning up our contamination,” Smith said.
Starring and Smith said that the science doesn’t support the plume’s westward migration. They say the remediation efforts in that area are directing the groundwater eastward toward their alfalfa fields. Although, the natural flow of groundwater in Hinkley is northwest toward Harper Lake, they said.
Kemper and the water board maintain that PG&E decreased the fresh water injection pumping significantly in that area during the fourth quarter of 2012 and the first quarter of 2013, which would have caused the plume migration.
“The water board doesn’t agree with that conclusion and we are still monitoring the data,” Kemper said.
Alfalfa farming is also being used as a major part of the remediation work by PG&E. The alfalfa plants naturally convert chromium 6 to the nutrient chromium 3. The third part of the clean-up is located at the heart of the plume where the original contamination occurred and comprises ethanol injections. The ethanol injections are the most effective at combating very high levels of chromium, which has been tested as high as 500 ppb and 1,000 ppb in the central area of the plume.
The current California drinking water standard is 50 ppb for total chromium, which includes both chromium 6 and chromium 3, they said. A draft new state drinking water standard is expected to be issued toward the end of the summer and will specifically address chromium 6.
While the process of cleaning up the groundwater in Hinkley is long and complex, Starring said the company wishes to “get it right” and meaningfully study all of the possibilities in the area as well as comply with the water board’s orders to investigate the westward expansion.
The final environmental impact report, which will permit PG&E to greatly increase their remediation efforts in Hinkley, is scheduled for approval next week on July 17. The public meeting will be held at the Lenwood Hampton Inn at 7 p.m.
For more information regarding the groundwater clean-up and the water board’s orders visit www.waterboards.ca.gov.