Hexavalent Chromium and Possum Point

When Dominion Power agreed last week to provide enhanced monitoring and protection for Quantico Creek and the Potomac River from the dewatering of the coal ash ponds at Dominion’s Possum Point Power Station they promised to perform enhanced monitoring for arsenic, selenium, lead, copper, antimony, and thallium. They did not mention hexavalent chromium. The reason is that hexavalent chromium is not regulated in Virginia or on a federal level. In September, 2010, EPA released a draft of the scientific human health assessment (Toxicological Review of Hexavalent Chromium) for public comment and external peer review, but has yet to finish the review, water issues are lower on their priority list.

Only a small fraction of the 80,000-100,000 potential drinking water contaminants are regulated. The EPA only regulates chemicals that are found to be prevalent in large water systems, are dangerous to public health and can be cost effectively removed. Currently, the EPA is analyzing data collected in its UCMR3 national drinking water monitoring program during 2013-2015 to understand the prevalence of chromium and hexavalent chromium exposure in large drinking water systems in the United States. However, hexavalent chromium is more likely to occur in groundwater and is quite persistent. Though hexavalent chromium can occur naturally, there are locations where chromium compounds have been released to the environment and groundwater in particular through leakage of waste storage ponds and improper industrial disposal practices.

Though Possum Point is downstream from nearby drinking water supplies; however, the current level of impact needs to be investigated and monitored for the 24 nearby private wells. Dominion’s enhanced monitoring should include testing of groundwater and the 24 nearby drinking water wells for hexavalent chromium to determine the extent of impact if any from the decades storage of the coal ash on site. The Prince William County Health District is taking the lead in providing water analysis for those homeowners and should include analysis for hexavalent chromium. There has been no testing of the 24 nearby drinking water wells for hexavalent chromium, but hexavalent chromium can be measured at levels as low as 0.02 ug/L by ion chromatography using a modified version of EPA Method 218.6 or EPA Method 218.7. However, at this time the homeowner will have to bear the cost of the analysis.

The owners of those nearby wells should contact the Department of Health and remember Hinkely, California located in the Mojave Desert. The groundwater in Hinkley became contaminated with hexavalent chromium from the compressor plant operated by Pacific Gas and Electric (PG&E). You may have heard of Hinkely or hexavalent chromium because of the movie “Erin Brockovich.”

In 1993, a legal clerk named Erin Brockovich investigated an elevated cluster of cancer in Hinkley that were linked to hexavalent chromium. Average hexavalent chromium levels in Hinkley were recorded as 1.19 parts per billion (ppb) with an estimated peak of 20 ppb. The PG&E Compressor Station averaged 7.8 ppb and peaks at 31.8 ppb based on the PG&E Background Study.

Though the U.S. Environmental Protection Agency (EPA) regulatory limit of total chromium at 100 ppb, and the EPA does not regulate hexavalent chromium at this time, it would be a tragedy not to verify that the nearby drinking water wells have not been impacted by the decades of coal ash storage at Possum Point. The California maximum contaminant level (MCL) for hexavalent chromium was lowered in 2014 to 0.01 ppb in drinking water. Hexavalent chromium in drinking water is not regulated in Virginia, only total chromium.

Chromium is an element that is found naturally in coal in what is called the trivalent oxidation state, Cr(III). Chromium exists in nature as either a component in clay minerals such as illite or chlorite, or as its oxidized components; small-particle chromium oxide (Cr2O3) or oxyhydroxide (CrOOH) carbonaceous components of coal, or more rarely as chromite (FeCr2O4), as a result of special geology. Chromium is a metallic element found in rocks, soils, plants, and animals.

Cr(III) is relatively non-hazardous to humans and is in fact an essential nutrient. Chromium in coal is not considered a serious health risk. However, during commercial coal combustion, coal is burned with excess air to raise heat to generate steam for turbines that produce electricity. In the process, significant quantities of ash are created from the incombustible inorganic components in coal. That ash can contain not only hexavalent chromium, but also arsenic, selenium, lead, copper, antimony, and thallium. Furthermore, there is the potential for greatly increasing the health risk associated with chromium because not only can its concentration in the ash be increased by up to 10 times compared to that in the original coal, but Cr(III) can also be oxidized during coal combustion to form Cr(VI), which poses a much greater threat to public health.

Hexavalent chromium is commonly referred to as: chromium 6, chromium VI, Cr(VI), Cr+6, or hex chrome. Hexavalent chromium in the form of chromates is very soluble and, because of the six available electrons it has a high oxidizing capability, and can have severe adverse effects on the human body, including cancerous tumor formation and gene damage. Research by the National Toxicology Program (NTP) has found that hexavalent chromium causes cancer in laboratory animals following oral ingestion at high doses (NTP, 2008). California Environmental Protection Agency’s Office of Environmental Health Hazard Assessment (OEHHA) analyzed data collected from China that found increased rates of stomach cancer in people who were exposed to very high levels of hexavalent chromium in drinking water (OEHHA, 2010).

Hexavalent chromium can be measured at levels as low as 0.02 ug/L by ion chromatography using a modified version of EPA Method 218.6 or EPA Method 218.7. Though I believe that Dominion Power should pay for the analysis, and the Prince William Health District should test to make sure that all residents of Prince William County have groundwater that is safe to drink, test your well for piece of mind.