245 Fischer Avenue, Suite D‐2 Costa Mesa, CA 92626 Tel. +1.714.770.8040 Web: www.aquilogic.com

January 15, 2018

TECHNICAL MEMORANDUM

To: Nate Benforado, Southern Environmental Law Center From: Anthony Brown, aquilogic, Inc. Michael Serfes, aquilogic, Inc

Subject: Review of Groundwater Conditions North Ash Pond at Dominion’s Bremo Power Station, Bremo Bluff, Fluvanna County, Virginia Project No.: 019‐08

Aquilogic, Inc. (aquilogic) has been retained by Southern Environmental Law Center (SELC) to provide expert consultation and analysis in connection with the coal ash ponds, specifically the North Ash Pond, located at the Bremo Power Station in Bremo Bluff, Virginia (the Site) (Figure 1). The scope of this phase of work was to evaluate groundwater and contaminant conditions at the Site, and how a closure plan following a cap‐in‐place approach would affect those conditions. As part of the evaluation we addressed the following questions:

1. Is groundwater within and beneath the North Ash Pond in direct hydrologic connection with surface waters, including the James River? 2. Is groundwater in contact with coal combustion residuals (CCR) or coal ash waste placed in the North Ash Pond? 3. Is the coal ash waste in the North Ash Pond contaminating groundwater? 4. Does coal ash waste pollution in groundwater discharge to surface waters, including the James River? 5. Is surface water at the Site in direct contact with coal ash waste? 6. Will capping of the North Ash Pond prevent the continued contamination of groundwater at the North Ash Pond? 7. Will capping of the North Ash Pond prevent the discharge of contaminated groundwater to the surface water, including the James River?

Our understanding, based on AECOM (2017), is that the CCR waste in the West Ash Pond has already been removed to the North Ash Pond and the CCR waste in the East Ash Pond (1.4 million cubic yards) will subsequently be removed to the North Ash Pond. Thus, all coal ash waste at the Site will be consolidated at the North Ash Pond. The transferred coal ash waste will be piled in an ash landfill on top of the existing coal ash waste in the North Ash Pond. Therefore, our evaluation will solely focus on the North Ash Pond. However, it should be noted

Privileged and Confidential Attorney Work Product 1

Review of Groundwater Conditions North Ash Pond at the Bremo Power Station that groundwater beneath the West and East Ash Basins in the natural hydrogeologic strata (floodplain alluvium deposits and underlying fractured bedrock) is highly contaminated with constituents from the coal ash waste in these ponds. Even with removal of the coal ash waste from the West and East Ash Basins, the residual contaminated groundwater will continue to discharge from the natural hydrogeologic strata beneath the ponds into the James River. Dominion needs to perform additional analysis to evaluate the vertical and horizontal extent of contamination under these ponds, estimate the duration over which this continued discharge will occur, and consider whether additional remediation is necessary.

SUMMARY OF EVALUATION

1. Is groundwater within and beneath the North Ash Pond in direct hydrologic connection with surface waters, including the James River?

Yes. Groundwater flows from areas with higher total hydraulic head (elevation in unconfined, water able aquifers) to areas of lower hydraulic head. In general, in natural hydrogeologic systems, groundwater flows from areas of recharge (usually at higher elevation) to areas of discharge (usually at lower elevation). The James River, located at an elevation of approximately 200‐feet above mean sea level (MSL) is the major groundwater discharge zone proximate to the Site (Figure 2).

The unlined North Ash Pond was constructed in 1983 by building an earthen dam across the outlet of an unnamed tributary of the James River about 1,200 feet from its original confluence with the James River (Figure 2). The earthen dam extended between the two natural promontories that form the valley sides of the watershed for the unnamed tributary. The tributary watershed extends upstream from the James River at 200 feet above MSL to about 450‐feet above MSL at the top of the watershed about 7,000 feet to the northeast. Thus, in general, the topographic surface slopes from northeast (NE) to southwest (SW); that is, from upstream areas down the watershed toward the James River. In general, groundwater flow will follow this topographic pattern, flowing from recharge areas upstream, through and beneath the North Ash Pond (where there is natural and anthropogenic recharge), to the James River where it discharges.

As coal ash waste has accumulated behind the dam, recharge from precipitation, sluice water, and groundwater from upgradient has caused the groundwater potentiometric surface (i.e., water table) in the North Ash Pond to rise above the natural land surface; thereby maintaining the coal ash waste in a saturated condition. In fact, groundwater‐ sustained ponded water is present immediately behind the dam.

The water table in the North Ash Pond is at about 320‐feet above MSL; that is, about 120 feet above the James River (200‐feet above MSL). Groundwater within and beneath the

Privileged and Confidential 2 Attorney Work Product

Review of Groundwater Conditions North Ash Pond at the Bremo Power Station

coal ash waste will flow toward, and discharge into, the James River in response to this head difference. In addition, recharge from precipitation and any sluice water at the North Ash Pond will create downward vertical hydraulic gradients from the coal ash waste into the underlying natural geologic formations: semi‐permeable weathered bedrock (saprolite) and the fractured bedrock (granodiorite). The vertical gradients would turn upward closer to the James River, as groundwater discharges to this surface water body. The exact location(s) of discharge will be controlled by the underlying geometry of the saprolite and the fracture network in the bedrock. The James River channel, approximately 1200‐feet southwest of the dam face, contains exposed fractured granodiorite bedrock (Haley and Aldridge, 2015).

The fracture network beneath the Site likely follows the NW‐SE trending dominant joint sets identified by the Virginia Division of Mineral Resources in VDMR (1969), and a secondary set oriented perpendicular (NE‐SW). The consistent NE‐SW orientation of local tributaries at the Site that flow to the James River likely reflects the presence of a perpendicular and complementary NE‐SW fracture orientation in addition to the dominant NW‐SE joint set described in VDMR (1969). The orientation of the James River (NW‐SE) and the unnamed tributary (NE‐SW) reflects the orientation of the underlying joint/fracture network; that is, NW‐SE with a secondary fracture set NE‐SW. The combination of natural recharge‐ discharge relationships (NE‐SW) and fracture/joint orientation results in the NE‐SW groundwater flow; that is, groundwater flow in both saprolite and fractured bedrock would be from the North Ash Pond to the James River. A south‐southwestward flow path from the North Ash Pond to the James River has been inferred by Consultants to Dominion (Haley and Aldridge, 2015; AECOM, 2017, Golder, 2017).

Therefore, groundwater beneath the North Ash Pond is in direct hydrologic connection with the James River.

2. Is groundwater at the Site in contact with coal combustion residuals (CCR) or coal ash waste placed in the North Ash Pond?

Yes. The Site contains three ash ponds (North, West, and East Ash Ponds) and all are in contact with groundwater (Figure 2). Currently, the North Ash Pond reportedly contains 4.8 million cubic yards of coal ash waste up to 90‐feet in thickness. An additional 1.4 million cubic yards of coal ash waste will be removed from the East Ash Ponds and placed in the North Ash Pond. The 6.2 million cubic yards of coal ash then present in the North Ash Pond and overlying ash landfill will be closed using a Cap‐in‐Place remedy.

As noted in Question 1, as coal ash waste has accumulated behind the dam, recharge from precipitation, any sluice water, and upgradient groundwater flow into the North Ash Pond, has caused the water table to rise above the natural land surface and into the coal ash waste. In fact, groundwater‐sustained ponded water is present immediately behind the

Privileged and Confidential 3 Attorney Work Product

Review of Groundwater Conditions North Ash Pond at the Bremo Power Station

dam. That is, nearly all of the coal ash waste in the North Ash Pond is in direct contact with groundwater (Golder, 2016; AECOM, 2017) and groundwater flows through the coal ash waste (Figure 3).

3. Is the coal ash waste in the North Ash Pond contaminating groundwater?

Yes. Coal ash waste in the North Ash Pond (as well as the West and East Ponds) is contaminating groundwater.

On the western rim of the North Ash Basin, boron, sulfate, and total dissolved solids (TDS) have been detected in groundwater samples from MW‐27S (unconsolidated saprolite overburden) above background levels. Boron, sulfate, TDS, lithium, molybdenum, nickel, and silver, have been detected in groundwater samples from MW‐27D (bedrock) above background levels. Boron, calcium, sulfate, TDS and nickel have been detected in groundwater samples from MW‐28 (saprolite) above background levels. Boron, calcium, lithium, and molybdenum have also been detected above background levels in down‐ gradient bedrock wells; MW‐33, MW‐34 and MW‐35 installed through the dam face. These contaminants of concern (COCs) have resulted from the dissolution of coal ash waste constituents into groundwater that has flowed through and below the North Ash Pond.

4. Does coal ash waste pollution in groundwater discharge to surface water, including the James River?

Yes. As discussed in Question 1, in response to recharge‐discharge relationships and the fracture geometry in the underlying hydrogeologic strata, groundwater flows from NE‐SW within and below the North Ash Pond. In addition, given the recharge at the North Ash Pond, groundwater also flows vertically downward from within the coal ash waste into the underlying saprolite and bedrock, and thence to the southwest. The groundwater then flows toward, and discharges to, the James River. The groundwater in the coal ash waste within the North Ash Pond, and the saprolite and fractured bedrock beneath the North Ash Basin, is contaminated with constituents from the coal ash waste (see Question 3), notably boron, sulfate, and TDS. The contaminated groundwater flows, and the contamination extends, to the southwest and thence discharges to the James River.

Therefore, coal ash waste pollution in groundwater discharges to surface water.

5. Is surface water at the Site in direct contact with coal ash waste?

Yes. As shown in Figure 3, standing water is ponded on the southern part of the North Ash Pond adjacent to the dam. This ponded water is in direct contact with coal ash waste and is in direct hydrologic connection with the underlying groundwater in the coal ash waste. Therefore, surface water in the North Ash Pond is in direct contact with coal ash waste.

Privileged and Confidential 4 Attorney Work Product

Review of Groundwater Conditions North Ash Pond at the Bremo Power Station

6. Will capping of the North Ash Pond prevent the continued contamination of groundwater at the North Ash Pond?

No. Capping the North Ash Pond will reduce the infiltration of direct precipitation into the coal ash waste and reduce groundwater recharge; however, it will not preclude all infiltration. More importantly, it will not reduce the continued flow of groundwater into the pond from up‐gradient. Upslope and northeast of the North Ash Pond, precipitation will continue to recharge groundwater as it does now. Groundwater in the upper part of the watershed within which the North Ash Pond was constructed, up‐gradient of the proposed cap‐in‐place geomembrane, has higher hydraulic head elevations (between 334 and 347 feet above MSL) than currently exists in the pond (320‐feet above MSL); for example, at monitoring wells MW‐29S (347‐feet), MW‐29D (334‐feet), MW‐26S (344‐feet) and OW‐26D (344‐feet). Therefore, in response to this head difference, groundwater will continue to flow to the southwest from upstream areas of the watershed into and beneath the coal ash waste in the North Ash Pond.

The water table in the North Ash Pond will decline slightly as a result of reduced infiltration. However, the dam will continue to partially restrict the flow of groundwater, and the groundwater flowing into the North Ash Basin from up‐gradient will still “back‐up” behind the dam. The water table within the North Ash Basin will still be within the coal ash waste. Constituents within the coal ash waste will continue to dissolve into and pollute the groundwater flowing through and below the North Ash Pond. Given the volume of coal ash waste in the North Ash Pond, constituents in the coal ash waste will dissolve into and pollute groundwater flowing through and beneath the North Ash Pond for centuries, essentially in perpetuity. Therefore, capping the North Ash Pond will not prevent continued contamination of groundwater.

As noted, groundwater is in direct contact with coal ash waste at the ash ponds. This condition will persist even after implementation of the proposal cap‐in‐place closure plan. According to the Electric Power Research Institute (EPRI), a utility industry trade group, “Caps are not effective when CCP (coal combustion product) is filled below the water table, because groundwater flowing through the CCP will generate leachate even in the absence of vertical infiltration through the CCP” (EPRI, 2006, pg. 3‐6).

7. Will capping of the North Ash Pond prevent the discharge of contaminated groundwater to surface water, including the James River?

No. As mentioned in Question 6, groundwater will continue to flow to the southwest within and beneath the coal ash waste in the North Ash Pond. In addition, as also mentioned in Question 6, constituents within the coal ash waste will continue to dissolve into and pollute the groundwater flowing through and below the North Ash Pond. The hydraulic head in the

Privileged and Confidential 5 Attorney Work Product

Review of Groundwater Conditions North Ash Pond at the Bremo Power Station

North Ash Pond will still be significantly higher than water in the James River. Even after capping, given the hydraulic head conditions, contaminated groundwater in the coal ash waste will continue to flow vertically downward into the saprolite and fractured bedrock. This contaminated groundwater will then flow to the southwest and discharge to the James River, even after capping. Given the volume of coal ash waste in the North Ash Pond, the discharge of contaminated groundwater to the James River would continue for centuries, essentially in perpetuity. Therefore, capping the North Ash Pond will not prevent the continued discharge of contaminated groundwater to the James River.

According to EPRI, “Caps are not effective when CCP (coal combustion product) is filled below the water table, because groundwater flowing through the CCP will generate leachate even in the absence of vertical infiltration through the CCP” (EPRI, 2006, pg. 3‐6).

SITE DESCRIPTION

The Site is an electricity‐generating facility (power plant) located on the northern bank of the James River in Fluvanna County, Virginia, in the Piedmont Physiographic Province, and is approximately 45 miles west of Richmond (Figure 1). It is situated on approximately 290 acres and is mostly bordered by undeveloped wooded parcels and a few single‐family residences (AECOM, 2017 section 6.2). The power‐plant was first operational in 1931 and used coal‐fired boilers which were converted to natural gas in 2014. Until that conversion took place, CCR, or simply coal ash waste, was produced as a waste by‐product of coal combustion. This coal ash waste was placed in three on‐site Ash Pond impoundments; the East, West and North (Figures 2 and 3). None of these impoundments are lined.

The topographic surface at the Site ranges from approximately 200‐feet above MSL at the James River to about 450‐feet above MSL upslope of the North Ash Pond where Bremo Road and Spring Road meet (Figure 2).

The three on‐site surface impoundments (East Ash Pond, West Ash Pond, and North Ash Pond) are subject to the requirements of SB 1398 and the CCR Rule. Under the proposed closure plan, all coal ash waste at the Site will be consolidated in the North Ash Pond (AECOM, 2017). Coal ash waste from the West Ash Pond has already been transferred to the North Ash Pond, and coal ash waste from the East Ash Pond is currently being moved to the North Ash Pond. The surface of the coal ash waste in the North Ash Pond is close to the height of the top of the earthen dam. Therefore, the coal ash waste from the East Ash Pond will be, and that from the West Ash Pond reportedly has been, piled on top of the existing coal ash waste in the North Ash Pond in an ash landfill. The ash landfill will rise about 13 feet above the current coal ash waste in the North Ash Pond if the 1.4 million cubic yards of CCR waste remaining in the East Ash Pond is evenly distributed over the reported 68 acres (AECOM, 2017). Once the consolidation is completed, approximately 6.2 million cubic yards of coal ash waste will be stored in the North

Privileged and Confidential 6 Attorney Work Product

Review of Groundwater Conditions North Ash Pond at the Bremo Power Station

Ash Pond (Figure 4). Under the proposed closure plan, the ash landfill and existing coal ash waste at the North Ash Pond will be covered by a multi‐layer liner.

NORTH ASH POND INFORMATION

The North Ash Pond was created by constructing an earthen dam approximately 96 feet tall across an unnamed tributary to the James River with no synthetic or clay liner beneath the ash (see Figure 2). Over time, coal ash waste from the power plant was placed behind, and northeast of, the earthen dam infilling the natural watershed. Currently, the North Ash Pond contains 4.8 million cubic yards of coal ash waste up to 90 feet thick (i.e., almost to the height of the dam), and the pond covers approximately 68 acres. The existing coal ash waste at the North Ash Pond is completely saturated with groundwater and ponded water above the coal ash waste is present immediately behind the dam.

The natural watershed for the unnamed tributary within which the North Ash Pond was constructed is approximately 103‐acres in area (see Figure 2). It is part of the 1.3 million‐acre Middle James‐Buffalo Watershed in the Piedmont Physiographic Provence in Virginia (Golder, 2016). Prior to construction of the North Ash Pond, the watershed contained an intermittent stream that flowed in a central valley onto the James River floodplain and thence discharged to the James River (Figure 2). Flow in the stream was maintained by intra‐basin groundwater flow, supplemented by overland flow during precipitation events.

The natural soils in the watershed consist of a typical Piedmont residual, saprolitic soil profile, formed from the in‐place weathering of the underlying granodiorite bedrock (Figure 4). Based on the 1982 Phase‐1 Dam construction diagrams in Golder (2016), depth to bedrock (which as defined as Stratum‐E) was less than 20‐feet in the central valley near the stream outlet to up to 50‐feet on the valley walls. Stratum‐E was described as: varicolored fresh to highly weathered Granodiorite Gneiss; very hard to soft; slightly to highly fractured.

The dam was constructed in two phases during 1982 and 1983 across a steep valley where the natural stream discharged from the watershed onto the James River floodplain (Figure 2). The dam is about 1000 feet in length and the main segment in the center of the stream valley is approximately 96‐feet high. The materials used to construct the dam were excavated from five main “borrow areas” in the watershed above the dam where coal ash waste would be placed. Geotechnical cross‐sections in Golder (2016) show that up to 50‐feet of overburden was removed in some borrow areas, suggesting that unconsolidated saprolite was removed almost down to the underlying fractured bedrock (Stratum‐E).

Privileged and Confidential 7 Attorney Work Product

Review of Groundwater Conditions North Ash Pond at the Bremo Power Station

SITE SURFACE WATER HYDROLOGY

The average annual precipitation in Fluvanna County, Virginia is approximately 41‐inches per year (Draper Aden Associates, 2010). The Site is in the James River Watershed that is part of the greater Chesapeake Bay Watershed and the James River flows eastward into the lower Chesapeake Bay. The Site is located in a in the 1,273,600‐acre Middle James‐Buffalo Watershed in the Piedmont Physiographic Provence in Virginia (Golder, 2016). The James River has the lowest local surface water elevation and is the major discharge zone for both surface water and groundwater at the Site. The Site occupies part of the floodplain adjacent to the north bank of the James River and upland areas beyond the floodplain further to the north, notably the infilled watershed of an unnamed tributary of the James River (i.e., the North Ash Pond).

The upland plateau at the Site and beyond to the north has been incised by several tributaries to the James River. Holman Creek flows across the property between the West Ash Pond and Bremo Power Plant and discharges to the James River through a culvert under the CSX railroad tracks. An unnamed, intermittent tributary was located about 1,500 feet southeast of the Bremo Power Plant. This tributary was dammed in 1982 and 1983 to create the North Ash Pond. The CSX railroad track sits on a raised berm above the north bank of the James River. This raised berm inhibits the ready flow of surface water from the Site to the river. Surface water that collects against the railroad berm is conveyed to one of the six outfalls that run beneath the railroad tracks. These discharges either flow directly into the James River or into drainage ditches that lead to culverts draining into the James River (VDEQ, 2016).

HYDRO‐STRATIGRAPHY

The Site is located in the Piedmont Physiographic Province of Virginia which lies between the Blue Ridge Province to the west and the Coastal Plain Province to the east. The Site is underlain by metamorphic and igneous bedrock that ranges in age from Precambrian (>570 million years) to Triassic (181‐230 million years) in geologic age (Figure 1). The bedrock has been exposed to compressive and extensional tectonic forces throughout its long history which have folded, faulted, jointed the rock and resulted in various rock‐specific metamorphic fabrics. The faults are generally more isolated linear features but the joints (patterned fractures in the rock) are more regionally pervasive. The fracture network provides the dominant pathway for groundwater flow in the bedrock. The most prominent joint sets in the study area are described in VDMR (1969) as being steeply dipping and having a northwest strike. However, a secondary set of joint/fractures usually occur perpendicular to the primary set. These joints/fractures control groundwater flow directions in the underlying bedrock portion of the aquifer system (VDMR, 1969). Thus, they would facilitate groundwater flow from northwest to southeast (NW‐ SE) and perpendicular to this from northeast to southwest (NE‐SW). The direction of groundwater flow will be also reflect recharge‐discharge relationships, such that if recharge is

Privileged and Confidential 8 Attorney Work Product

Review of Groundwater Conditions North Ash Pond at the Bremo Power Station predominately to the north (in the upland areas) and discharge to the south (at the James River), then groundwater will generally flow north to south. However, the fracture networks will essentially deflect this flow to either a NW‐SE or NE‐SW direction along the joint/fracture network.

The Site, specifically the North Ash Pond, is underlain by various granodioritic rocks of the Chopawamsic Terrane (a land mass that accreted to the east coast during a subduction phase) and were formerly called the Hatcher Complex (VDMR, 1969). A geologic site map of the Site area is shown in Figure (4).

The Piedmont Province is characterized by rolling to hilly topography, the steepest of which are along the major streams such as the James River that have cut deeply into the upland plateau (Draper Arden Associates, 2010). The Province contains deeply weathered bedrock that forms a thick layer of unconsolidated to semi‐consolidated saprolite overburden above the bedrock. The saprolite materials (overburden or regolith) are up to 100‐feet thick in some places but absent in some stream channels where the underlying bedrock is exposed. Given that the saprolite is a porous media, the groundwater potentiometric surface in the saprolite likely reflects the topography of the land surface above. Thus, groundwater in the saprolite will flow from upland recharge areas to lowland discharge areas, notably the James River and its tributaries.

As previously mentioned, the average annual precipitation in Fluvanna County, Virginia is approximately 41‐inches per year. Of that total, some is evaporated directly from the land surface, some is transpired by plants back into the atmosphere, and some, called runoff, flows along the ground surface directly into surface‐water drainages. The remainder infiltrates into the surface soils or rock and percolates down to the water table, recharging groundwater.

Throughout the Piedmont Physiographic Province of Virginia groundwater occurs within two basic hydro‐stratigraphic units: within pores in the overburden materials (mostly saprolite), and in the fractures in the bedrock. These two groundwater‐bearing units are commonly described as the Water Table Aquifer and the Bedrock Aquifer. However, this colloquial separation is misleading because the Water Table Aquifer and shallow fractures in the Bedrock Aquifer are not isolated from each other and are generally hydraulically interconnected; therefore, they behave as a single aquifer system (Draper Aden Associates, 2010).

Given the hydro‐stratigraphic sequence and hydraulic head conditions, notably the downward vertical gradient, any assessment of groundwater conditions, and contaminant presence, magnitude, extent, and transport should investigate both the saprolite and fractured bedrock. In particular, detailed characterization of groundwater flow and contaminant conditions in the fractured bedrock between the North Ash Pond and the James River is required. It is likely that

Privileged and Confidential 9 Attorney Work Product

Review of Groundwater Conditions North Ash Pond at the Bremo Power Station significant contamination is being transported from the North Ash Pond along fractures in the bedrock to the James River.

At the North Ash Pond, the saprolite ranges up to about 50‐feet in thickness and is generally thickest in the upland areas. Under the pond itself, the overburden is reported to range in thickness from 15 to 50‐feet (AECOM, 2017 section 6.2). However, in borrow areas used to generate materials for dam construction, the saprolite may be thinner and even absent. The saprolite overburden grades downward into the parent fractured granodioritic rock types (Figure 4). Groundwater occurs in intergranular pores in the saprolite which contains most of the groundwater storage, and in fractures and other openings in the underlying granodioritic bedrock.

Bedrock wells installed in granodioritic gneiss and meta‐volcanic rocks, the same as those under the North Ash Pond, are reported in Draper Arden Associates (2010) to have average well yields of 14.1 and 12.3 gallons per minute (gpm), respectively, and a few have reported yields over 50‐ gpm in these same rock types. These yields are ample for residential water supplies and indicate that there is a generally good hydraulic connection between the saprolite overburden and underlying bedrock and that the fractured granodioritic bedrock readily transmits water. It is reasonable to conclude that the same hydraulic conditions exist at the Site.

On the eastern rim of the North Ash Pond, two well clusters (MW‐25 and MW‐26) each have one shallow monitor well (MW) in what was described by Golder (2017) as saprolite‐bedrock and one deeper observation well (OW) in bedrock (Figure 4). MW‐25S and OW‐25D have approximately the same hydraulic head (319‐feet) and hydraulic conductivity (10‐4 centimeters per second). MW‐26S and OW‐26D also have the same hydraulic head (344‐feet) and the hydraulic conductivity at OW‐26D is similar to those at the MW‐25 cluster (no hydraulic conductivity data was provided for MW‐26S). These similar hydraulic characteristics indicate a good hydraulic connection between the shallow and deeper portion of the aquifer on the eastern rim of the North Ash Pond and an uniformity in their ability to transmit water. Reported groundwater quality data (AECOM, 2017) indicates there were no contaminants at concentrations of concern in either MW‐25S or MW‐26S; however, no groundwater quality data was provided for OW‐25D or OW‐26D.

GROUNDWATER FLOW AND DISCHARGE TO SURFACE WATER

The water table beneath the Site generally follows the landscape topography, although in a subdued form. Thus, groundwater flow also follows the topography, flowing from areas of recharge to the northwest above the North Ash Pond, through and beneath the North Ash Pond (where additional recharge occurs), and discharging at locations between the dam and the James River.

Privileged and Confidential 10 Attorney Work Product

Review of Groundwater Conditions North Ash Pond at the Bremo Power Station

Much of the groundwater investigation work focused on the James River floodplain adjacent to the West and East Ash Ponds. There has been very limited investigation of groundwater and contaminant conditions in the bedrock directly under, and between, the North Ash Pond and the James River, and the nature of the discharges from bedrock to the James River.

GROUNDWATER AND SURFACE WATER CONTAMINATION

Groundwater Contamination

Coal ash waste contains enriched concentrations of major, minor and trace elements that existed in the parent coal that was burned as a fuel to generate power. As the flue gas cools down after combustion, elements such as arsenic, boron, mercury, chloride, chromium, selenium and most prominently sulfur, condense on the surface of the fly ash particles making them particularly available for mobilization under the right aqueous geochemical conditions (Izquiedo and Querol, 2012). The flue gas will also contain numerous trace metals, notably cobalt, nickel, zinc, cadmium, antimony, lead, vanadium and uranium (USGS, 2015). Many of these constituents within the coal ash waste are toxic to humans and ecosystems. Water that contacts coal ash waste becomes highly contaminated due to the dissolution of some constituents and desorption of trace elements from CCR particle surfaces into the aqueous phase (Izquiedo and Querol, 2012; USGS, 2015; Harkness and others, 2016).

COC associated with coal ash waste have been detected in groundwater samples collected from several monitoring wells at the Site. These monitoring wells are installed in: (1) the unconsolidated materials in the James River floodplain, down‐gradient of the East Ash Pond, (2) shallow overburden (saprolite) and deep bedrock well clusters (MW‐27S/27D) and MW‐28 (saprolite) on the western rim of the North Ash Pond; and (3) bedrock wells MWs‐33, 34, and 35 installed through the dam. The coal ash waste contaminated wells around the North Ash Pond are highlighted in Figure (4). This groundwater‐quality information was briefly described in Question 2.

The following ground‐water quality information is from “CCR Compliance Data Tables for the North Ash Pond, TM6‐5” provided in AECOM (2017). Boron, calcium, fluoride, lead, lithium, molybdenum, nickel, silver, sulfate, and TDS were detected in groundwater samples from six monitoring wells around the North Ash Basin at concentrations above background levels. The six monitoring wells are located on the west rim of North Ash Pond (MW‐27S, MW‐27D, MW‐ 28), and at the base of dam (MW‐33, MW‐34, MW‐35) (see Figure 4). Each of the monitoring wells, the hydro‐stratigraphic zone across which they are screened, and the coal ash waste constituent detected at each well above background concentrations during eight quarterly sampling rounds are listed below:

1. MW‐27S (saprolite): Boron, calcium, sulfate, silver, and TDS

Privileged and Confidential 11 Attorney Work Product

Review of Groundwater Conditions North Ash Pond at the Bremo Power Station

2. MW‐27D (bedrock): Boron, calcium, fluoride, sulfate, TDS, lead, lithium, molybdenum, nickel, and silver 3. MW‐28 (saprolite): Boron, calcium, sulfate, TDS, and nickel 4. MW‐33 (bedrock): Boron and calcium 5. MW‐34 (bedrock): Boron 6. MW‐35 (bedrock): Boron, calcium, lithium, and molybdenum

These COCs have resulted from the dissolution of coal ash waste constituents into groundwater that has flowed through and below the North Ash Pond.

As noted, groundwater quality data are provided for MW‐25S and MW‐26S installed in the saprolite‐bedrock material on the eastern rim of the North Ash Pond, and concentrations did not exceed background levels (AECOM, 2017). However, no groundwater quality data are provided for the deeper bedrock wells OW‐25D and OW‐26D located alongside MW‐25S and MW‐26S, respectively. In addition, farther down‐gradient wells MW‐6 through MW‐8, MW‐10, and MW‐14 through MW‐18 (which are also down‐gradient of the East Ash Pond) were not sampled in 2016 and 2017 by AECOM (Figure 4). However, these wells were sampled by Haley & Aldridge in 2015, and the following coal ash constituents were detected at one or more well above background concentrations: arsenic, barium, boron, chloride, hardness, sulfate, TDS, and zinc.

Surface Water Contamination

Four water samples were collected from the James River, two upstream and two downstream of the Site, between April 2016 and March 2017. Analyte concentrations detected in these samples were below Virginia Surface Water Quality Standards for aquatic life and human health for all constituents (AECOM, 2017). However, the surface water monitoring conducted in the James River was limited and potentially biased due to the fact that the locations selected for sampling did not consider the mechanisms and locations of groundwater discharges to the James River: bed seepage (notably along fractures in bedrock exposed on the river bottom), bank seeps, and stream channels between the dam and James River.

CONTAMINATION SUMMARY

Groundwater at the Site flows from areas of recharge upstream of the North Ash Pond, through and below the North Ash Pond, and further to the southwest where it discharges to the James River. Constituents in the coal ash waste in the North Ash Pond dissolve into groundwater within and flowing through the coal ash waste. Contaminated groundwater in the coal ash waste flows laterally to the southwest through and beneath the dam at the North Ash Pond. Contaminated groundwater also flows vertically into the saprolite and fractured bedrock, and thence laterally to the southwest toward the James River. Contaminated groundwater

Privileged and Confidential 12 Attorney Work Product

Review of Groundwater Conditions North Ash Pond at the Bremo Power Station discharges at seeps in the dam that flow to streams that drain to the James River, as bed seepage into these streams, as bank seeps along the James River, and as bed seepage at the James River. Coal ash waste constituents have been detected above background levels in samples from monitoring wells down‐gradient of the dam. These contaminants include boron, calcium, fluoride, lead, lithium, molybdenum, nickel, silver, sulfate, and TDS.

CAP‐IN‐PLACE CLOSURE OPTION

AECOM submitted, on behalf of Dominion, a response to Senate Bill (SB) 1398 to the Virginia Department of Environment Quality (AECOM, 2017). This response document assessed several closure options for the Site including Cap‐in‐Place. A review of the Cap‐in‐Place closure option has been completed. Under the closure‐in‐place option, the CCR waste from both the West Ash Pond and the East Ash Pond will be removed to the North Ash Pond where all CCR waste will be consolidated. The transferred coal ash waste will be piled in an ash landfill on top of the existing coal ash waste in the North Ash Pond and capped (AECOM, 2017).

No details have been provided as to the design of the final engineered cover system. In general, one component of the cover systems includes the installation of a 40 mil High Density Polyethylene (HDPE) geo‐membrane liner. The geo‐membrane liner is intended to limit the infiltration of water into the ash ponds, and subsequent percolation of water to groundwater. In addition, soil cover will be vegetated to minimize soil erosion in the final cover system.

Caps or liners are rarely, if ever, fully effective in preventing infiltration of precipitation to groundwater. Due to geomembrane defects or installation issues (e.g. liner punctures), the cap/liner itself allows some water to leak across the geomembrane and recharge groundwater. In addition, over time, such caps are vulnerable to degradation and damage from at least the following mechanisms (Environmental Research Foundation, 2003):

 Natural weathering (rain, hail, snow, and wind).  Sunlight (membrane degradation through the action of ultraviolet radiation resulting in cracking and flaking).  Vegetation (sending down roots that can penetrate the cap/liner or widen cracks and holes created by other mechanisms).  Burrowing or soil‐dwelling animals (e.g., woodchucks, mice, moles, voles, snakes, insects, and worms) (penetrating a cap/liner, widening cracks and holes created by other mechanisms, and creating voids that result in differential settlement which results in subsidence).  Subsidence (where uneven settling or cave‐in beneath the cap causes a void beneath the cap/liner and can result in tears in geomembrane liners, or result in ponding of water on the surface, which can subject the cap to increased freeze‐thaw pressures).

Privileged and Confidential 13 Attorney Work Product

Review of Groundwater Conditions North Ash Pond at the Bremo Power Station

 Human activities of many kinds (most notably the driving of vehicles on the cap that tear the liner or cause other damage).

Thus, over time, these mechanisms can result in higher rates of leakage across the cap, increased percolating water, increased groundwater recharge, and continued groundwater flow toward, and discharge to, the surrounding surface waters.

As noted above, the proposed geomembrane cap should reduce, but not eliminate, the percolation of infiltrating precipitation. As a result of continued percolation of water, the contaminants in the coal ash waste above the groundwater surface (in the vadose zone) will continue to dissolve into the percolating water and continue to add contaminant mass to the groundwater.

In addition, even after the cap is installed, a significant portion of coal ash in the North Ash Pond will remain below the groundwater table under the proposed closure plan. According to the EPRI, “Caps are not effective when CCP is filled below the water table, because groundwater flowing through the CCP will generate leachate even in the absence of vertical infiltration through the CCP” (EPRI, 2006, pg. 3‐6).

More importantly, the cap will not affect up‐gradient infiltration and percolation of precipitation in the up‐land areas of the catchment. In addition, it will not affect the lateral flow of up‐ gradient groundwater from these up‐land areas through the North Ash Pond and to discharge points along the James River. Thus, contaminated groundwater will continue to flow toward, and discharge to, the surrounding surface waters after cap installation. For this closure plan, the coal ash waste will be present and be a long‐term source of contamination (i.e., in perpetuity).

In summary, even after placement of the cap at the North Ash Pond, coal ash constituents will continue to dissolve into groundwater within, and flowing through, the North Ash Pond. This groundwater contamination will persist for many centuries, essentially in perpetuity. Contaminated groundwater will flow laterally to the southwest toward the James River, and vertically into the saprolite and fractured bedrock, and thence laterally to the James River. Even after placement of the cap at the North Ash Pond, contaminated groundwater will discharge to the James River for many centuries, essentially in perpetuity.

REFERENCES

AECOM. (2017). Senate Bill 1398 Response: Coal Combustion Residuals Ash Pond Closure Assessment, Prepared for Dominion Energy by AECOM. November. Draper Aden Associates. (2010). Fluvanna County Regional Water Supply Plan: prepared for Fluvanna County and Town of Columbia, 174 p.

Privileged and Confidential 14 Attorney Work Product

Review of Groundwater Conditions North Ash Pond at the Bremo Power Station

EPRI. (2006). Groundwater Remediation of Inorganic Constituents at Coal Combustion Product Management Sites: Overview of Technologies, Focusing on Permeable Reactive Barriers (pg. 102, Rep. No. 1012584). Palo Alto, CA: EPRI. Environmental Research Foundation. (2003). The Basics of Landfills. Retrieved from http://www.ejnet.org/landfills/. March 26. Golder Associates, Inc. (2016). History of Construction, Bremo Power Station CCR Surface Impoundment: North Ash Pond. October 13. Golder Associates, Inc. (2017). Groundwater Monitoring Plan: Bremo Power Station; Prepared for Dominon. February 2017. Haley & Aldrich, Inc. (2015). Risk Assessment, Bremo Power Station, Bremo Bluff, Virginia. July. Harkness, J., Sulkin, B., & Vengosh, A. (2016). Evidence for Coal Ash Ponds Leaking in the Southeastern United States: Environ. Sci. Technol., 50, 6583−6592. Izquierdo, M. & Querol, X. (2012). Leaching behavior of elements from coal combustion fly ash: an overview. Int. J. Coal Geol. 2012, 94, 54− 66. VA SB 1398. (2017). Virginia Acts of Assembly‐Chapter: An Act to Require Evaluation of Closure of Coal Combustion Residuals. Retrieved from: https://lis.virginia.gov/cgi‐ bin/legp604.exe?171+ful+SB1398ER2+pdf. USGS. (2015). Trace Elements in Coal Ash; Fact Sheet 2015‐3037, USDI, USGS, 6 p. Virginia Division of Mineral Resources (VDMR). (1969). Geology of the Dillwyn Quadrangle Virginia. Report of Investigations 10. Commonwealth of Virginia Department of Conservation and Economic Development Division of Mineral Resources. By William Randall Brown. Charlottesville, Virginia. Virginia Department of Environmental Quality (VDEQ). (2016). VPDES Permit Number VA0004138 Dominion – Bremo Power Station: Presentation given at State Water Control Board Meeting, January 14, 2016. Retrieved from: http://www.deq.virginia.gov/Portals/0/DEQ/ConnectwithDEQ/EnvironmentalInformatio n/Coal%20Ash/Board%20Staff%20Presentation%20VA0004138%20Bremo%201‐14‐ 16.pdf.

Privileged and Confidential 15 Attorney Work Product NEW JERSEY ^ Site Location PENNSYLVANIA Generalized Fall Line Geologic Provinces Coastal Plain Piedmont Blue Ridge OHIO Valley and Ridge MARYLAND Appalachian Plateaus

UV7 DISTRICT OF COLUMBIA

DELAWARE

WEST VIRGINIA ¤£29

Bremo Power Station

KENTUCKY

¤£29 ^

¤£220 ¤£360

TENNESSEE Z 0 40

Miles NORTH CAROLINA Bremo Power Station Bremo Bluff, Virginia Site Location and State Geologic Provinces

Date: 12/19/2017 Project #: 019-08 Figure 1 GEORGIA SOUTH CAROLINA Bremo Power Station Bremo Bluff, Virginia

Source: Golder Associates, Inc. (2017). Groundwater Monitoring Plan: Site Location and Topography Bremo Power Station (Drawing 1); Prepared for Dominon. February 2017. Date: 1/11/2018 Project #: 019-08 Figure 2 Bremo Power Station Bremo Bluff, Virginia

Site Location Map

Source: AECOM. (2017). Senate Bill 1398 Response: Coal Combustion Residuals Ash Pond Closure Assessment (Fig. 1), Prepared for Dominion Energy by AECOM. Nov. 2017 Date: 1/11/2018 Project #: 019-08 Figure 3