Dominion Releases Possum Point Groundwater Monitoring Report

If you recall, Dominion Power has the Possum Point Power Station in Prince William County. The Possum Point Power Station currently has four active power generating units that use natural gas and/or oil. Two of these operating units were converted from coal to natural gas in 2003. Historically, Possum Point stored the Coal Combustion Residuals (coal ash) in five surface impoundments. All the coal ash has been moved and placed in Pond D.

Dominion Power has been moving forward with a plan to “close in place” the 3.7 million cubic yards of coal ash now in Pond D under the finalized U.S. EPA Coal Ash regulation. The plan for Possum Point was to dewater the coal ash, the cap Pond D with an impermeable membrane to prevent future infiltration of rain and “dispose” of the coal ash by leaving it on the Possum Point site.

In 2015, the U.S. Environmental Protection Agency (EPA) promulgated rules for handling coal ash, which were then adopted in Virginia by the Department of Environmental Quality (DEQ) in the Virginia Solid Waste Management Regulations. This rule addresses the risks from structural failures of coal ash surface impoundments like Pond D, and includes location restrictions, design and operating criteria, groundwater monitoring and (if needed) corrective action, closure requirements and post‐closure care, and recordkeeping, and public disclosure.

Dominion Power was required to complete an initial annual groundwater monitoring and corrective action report by January 31, 2018, and annually thereafter. Dominion Power has just release the results of their first year of monitoring. This report identifies groundwater conditions at Pond D. Groundwater monitoring wells were installed around the pond, both upgradient (wells that should reflect background conditions) and downgradient (wells that that indicate if groundwater was impacted by the pond). There are two upgradient wells ED-24 and ED-1612 and six downgradient monitoring wells (ED-1D, ED-9R, ED-1605, ED-1606, SD-1603, and SD-1604). These wells are shallow and monitor the uppermost aquifer beneath the coal ash pond.

from Dominion Power

Possum Point and surrounding area are located entirely within the Coastal Plain physiographic province of Virginia. The geology is characterized by unconsolidated sediments that generally form broad terraces that slope towards the east. The terraces are transected by natural surface drainage channels, some of which were filled in. The unconsolidated sediments consist of clays, silts, sands, and gravel that exist as interbedded, discontinuous, horizontal layers across the site. The thickness of the sedimentary sequence ranges up to 600 feet as determined by well logs for the surrounding area.

The Potomac Confining Unit is considered to be a confining unit for the underlying Potomac Aquifer. It has always been assumed that the two aquifers are physically and hydrologically separated by the Potomac Confining Unit, but in recent years there has been observed some limited interchange between the uppermost aquifer which is within the overlaying sediments and the lower Potomac Aquifer and contaminants within the uppermost aquifer may be able to migrate into the drinking water supply in the lower aquifer.

The first groundwater monitoring report found occasional instances where tests of downgradient wells showed elevated levels of heavy metals associated with coal ash. The sampling found traces of arsenic, boron, cadmium, calcium, chloride, cobalt, hardness, iron, lithium, manganese, nickel, phenol, sodium, sulfate, total dissolved solids (TDS), and zinc down gradient of coal ash Pond D; however, the concentrations found were below the federal Safe Drinking Water Standards for those substances that have them (lithium does not have a drinking water standard).

Dominion Power pointed out that “The data in the 2017 Annual Groundwater Report do not indicate that groundwater from Pond D is impacting public drinking water supplies or presenting an environmental risk.” However, they only tested the quality of the groundwater around the edges of the coal ash Pond D which is not a drinking water supply. They only looked at the shallow aquifer upgradient and downgradient of Pond D, not in the area of any drinking water wells.

Groundwater impacts were observed. As Dominion Points out no impact to human health or the environment was found, but it was not looked for. It is clear by the presence of contaminants in the surrounding aquifer that the coal ash ponds at Possum Point were not adequately lined or had a functioning barrier (there is some question if there was a slurry wall installed to prevent impact to the groundwater in 1988) there is clearly hydraulic communication between Pond D and the surrounding groundwater. The coal ash has been impacting groundwater for decades. Pond D does not appear to be and adequate containment for the coal ash to be permanently disposed in. Additional groundwater monitoring is needed to determine what corrective measures are needed to safely dispose of the coal ash in this way, though consideration should also be given to removal and recycling of the coal ash into concrete and road base.