Umetco Minerals Corporation

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1 Umetco Minerals Corporation 310 George Patterson Blvd, suite 100, Bristol, Pennsylvania (215) March 30, 2016 Ms. Linda A. Hanson, P.G. Arkansas Department of Environmental Quality Water Division 5301 Northshore Drive North Little Rock, Arkansas Subject: 2015 Annual Groundwater Report EVRAZ Stratcor, Inc. (Former U.S. Vanadium) Plant Site, Hot Springs, Arkansas Consent Administrative Order LIS Please find attached the 2015 Annual Groundwater Report submitted in accordance with Consent Administrative Order LIS for the EVRAZ Stratcor, Inc. (former U.S. Vanadium) Plant Site at Hot Springs, Arkansas. This report also addressed some of the observations on the 2014 Annual Groundwater Report provided by ADEQ in multiple correspondence in If you have any questions regarding this information, please contact me at Sincerely, James F. Strunk, Jr., P.E. Remediation Leader Authorized Representative Umetco Minerals Corporation cc: Shane Weatherford, EVRAZ Stratcor, Inc. Susan Hayes, Umetco Minerals Corporation Project File Martin Powers, CH2M HILL

2 2015 Annual Groundwater Report EVRAZ Stratcor Plant Site Hot Springs, Arkansas Prepared for Umetco Minerals Corporation March 2016

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6 Contents Section Page Contents... iii Acronyms and Abbreviations... v 1 Introduction Background Site Location and History Site Hydrogeology Groundwater Monitoring Groundwater Recovery System Field Activities Potentiometric Monitoring Groundwater Sample Collection Laboratory Methods Flow Totalizers Operations and Maintenance Activities Results Groundwater Flow Hydrographs Groundwater Quality Chloride Sulfate Total Dissolved Solids Calcium Sodium Nitrate-Nitrite (as Nitrogen) Vanadium Summary Groundwater Recovery System Performance References Appendixes A B 2015 Analytical Laboratory Packages 2015 Data Tables EN NWO iii

7 2015 ANNUAL GROUNDWATER REPORT, EVRAZ STRATCOR PLANT SITE, HOT SPRINGS, ARKANSAS Tables 3-1 Monitoring Well Construction Details and Measured Groundwater Elevations 3-2 Recovery Well Construction Details and Measured Groundwater Elevations Groundwater Field Parameter Results Measured in the Alluvium Groundwater Field Parameter Results Measured in the Stanley Shale 4-3 First Quarter 2015 Alluvium Analytical Results 4-4 Second Quarter 2015 Alluvium Analytical Results 4-5 Third Quarter 2015 Alluvium Analytical Results 4-6 Fourth Quarter 2015 Alluvium Analytical Results 4-7 First Quarter Stanley Shale Analytical Results 4-8 Second Quarter Stanley Shale Analytical Results 4-9 Third Quarter Stanley Shale Analytical Results 4-10 Fourth Quarter Stanley Shale Analytical Results Figures 2-1 Location Map, EVRAZ Stratcor Plant Site 2-2 Monitoring and Recovery Well Location Map 4-1 Alluvium Groundwater Levels, Fourth Quarter Stanley Shale Groundwater Levels, Fourth Quarter A Hydrograph: Monitoring Wells UO and UO B Hydrograph: Monitoring Wells UO and UO A Hydrograph: UO and UO B Hydrograph: UO and UO Hydrograph: UO and UO A Chloride Concentrations in Alluvium Groundwater Linear Scale 4-6B Chloride Concentrations in Alluvium Groundwater Logarithmic Scale 4-7A Chloride Concentrations in Stanley Shale Groundwater Linear Scale 4-7B Chloride Concentrations in Stanley Shale Groundwater Logarithmic Scale 4-8 Sulfate Concentrations in Alluvium Groundwater 4-9 Sulfate Concentrations in Stanley Shale Groundwater 4-10A Total Dissolved Solids Concentrations in Alluvium Groundwater Linear Scale 4-10B Total Dissolved Solids Concentrations in Alluvium Groundwater Logarithmic Scale 4-11A Total Dissolved Solids Concentrations in Stanley Shale Groundwater Linear Scale 4-11B Total Dissolved Solids Concentrations in Stanley Shale Groundwater Logarithmic Scale 4-12 Calcium Concentrations in Alluvium Groundwater 4-13 Calcium Concentrations in Stanley Shale Groundwater 4-14 Concentrations in Alluvium Groundwater 4-15 Sodium Concentrations in Stanley Shale Groundwater 4-16 Nitrate-Nitrite (as N) Concentrations in Alluvium Groundwater 4-17 Nitrate-Nitrite (as N) Concentrations in Stanley Shale Groundwater 4-18 Dissolved Vanadium Concentrations in Alluvium Groundwater 4-19 Dissolved Vanadium Concentrations in Stanley Shale Groundwater 4-20 Isoconcentration Figure: Chloride in Alluvium Groundwater 4-21 Isoconcentration Figure: Chloride in Stanley Shale Groundwater 4-22 Isoconcentration Figure: Sulfate in Alluvium Groundwater 4-23 Isoconcentration Figure: Sulfate in Stanley Shale Groundwater 4-24 Isoconcentration Figure: Total Dissolved Solids in Alluvium Groundwater 4-25 Isoconcentration Figure: Total Dissolved Solids in Stanley Shale Groundwater 4-26 Recovery Volumes iv EN NWO

8 Acronyms and Abbreviations µ micron ADPC&E Arkansas Department of Pollution Control and Ecology APHA American Public Health Association CAO Consent Administrative Order LIS CH2M CH2M HILL Engineers, Inc. EVRAZ Stratcor EVRAZ Stratcor, Inc. ft foot ft amsl foot above mean sea level mg/l milligram per liter N nitrogen No. number NPDES National Pollutant Discharge Elimination System Plant Site former U.S. Vanadium, current EVRAZ Stratcor Plant Site Q1 first quarter Q2 second quarter Q3 third quarter Q4 fourth quarter SM Standard Method TDS total dissolved solids U.S. United States USEPA U.S. Environmental Protection Agency Umetco Umetco Minerals Corporation UO Umetco Observation (monitoring well) UR Umetco Recovery Well EN NWO v

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10 SECTION 1 Introduction This report summarizes the results of groundwater monitoring activities conducted during 2015 at the former U.S. Vanadium Plant Site (Plant Site) in Hot Springs, Arkansas. The Plant Site is currently owned and operated by EVRAZ Stratcor, Inc. (EVRAZ Stratcor). Pursuant to the Consent Administrative Order LIS (CAO), Umetco Minerals Corporation (Umetco) has been monitoring groundwater quality in the approved monitoring network since A groundwater recovery system was installed in 1991 consisting of 13 extraction wells and a groundwater interceptor trench (i.e., French drain). The groundwater recovery system came online in August Startup of the French drain occurred in October Activities associated with groundwater monitoring and recovery well operations conducted during 2015 included the continued pumping and treatment of groundwater, quarterly groundwater monitoring, and system maintenance. EN NWO 1-1

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12 SECTION 2 Background 2.1 Site Location and History The Plant Site is located in Garland County, Arkansas, approximately 7 miles east of the city of Hot Springs (Figure 2-1). The Plant Site lies within portions of Sections 16, 17, and 21 of Township 3 South, Range 18 West. The groundwater recovery system installed at the Plant Site began operations in August The recovered groundwater is managed along with EVRAZ Stratcor Plant effluent before being discharged through Outfall 001B under EVRAZ Stratcor s approved National Pollutant Discharge Elimination System (NPDES) permit (Permit Number [No.] AR ). A network consisting of 35 monitoring wells is used to monitor groundwater conditions at the Plant Site. Additionally, there are 13 wells used to recover shallow groundwater beneath the Plant Site. A 262-foot-long groundwater interceptor trench (French drain) along the southern boundary of the Plant Site augments the groundwater recovery system, capturing groundwater from the uppermost waterbearing zone. 2.2 Site Hydrogeology Shallow groundwater beneath the Plant Site exists in two different water-bearing zones: Quaternary alluvium and the Mississippian Stanley Shale. The lateral extent and thickness of the alluvium have been delineated in previous studies from boring logs and field mapping (Owens and Hollingsworth 1986; B&F Engineering 1988a and 1988b). These studies have shown that although the alluvium has a limited areal extent, it is present beneath most of the Plant Site. The Mississippian Stanley Shale represents the uppermost bedrock layer beneath the alluvium. Groundwater flows within and between both the alluvial and Stanley Shale units. Groundwater in the alluvium exists under unconfined conditions, and groundwater flow occurs through primary porosity. Groundwater in the Stanley Shale exists under unconfined and leaky confined conditions. Groundwater flow within the shale is predominantly through secondary fracture porosity (Yancey and Associates 1998). The Stanley Shale is hydraulically connected to the alluvium. The natural depth to groundwater at the Plant Site ranges from a few feet to approximately 20 feet (ft) below ground surface. Seasonal fluctuations in water levels typically cause the saturated thickness in the alluvium to vary by an average of 6 ft, based on historical records. 2.3 Groundwater Monitoring There are 35 Umetco Observation (UO) monitoring wells at the Plant Site used to monitor groundwater conditions. Nineteen of these UO monitoring wells are screened in the alluvium, and 16 are screened in the Stanley Shale. Many of the UO monitoring wells were installed as nested pairs, with the upper well completed in the alluvium, and the lower well completed in the Stanley Shale. The well locations in both zones are shown on Figure Groundwater Recovery System Of the 13 recovery wells, 5 are within the alluvium, and 8 are within the Stanley Shale. The recovery well locations in the alluvium and Stanley Shale are shown on Figures 2-2. Each recovery well name begins with a UR prefix. EN NWO 2-1

13 2015 ANNUAL GROUNDWATER REPORT, EVRAZ STRATCOR PLANT SITE, HOT SPRINGS, ARKANSAS After the groundwater recovery system began pumping, groundwater levels within the pumping radius-of-influence were lowered by as much as 10 to 12 ft. For example, prior to groundwater recovery, the water level in monitoring wells UO and UO typically fluctuated between 392 and 400 feet above mean sea level (ft amsl). Since pumping began, the groundwater level in these wells has ranged from 380 to 400 ft amsl, with many readings near the low end of this range during the first 8 years of system operation. Groundwater recovery has also reduced the average water level in wells UO and UO by about 5 feet since the system came online. Additional discussion of water level changes over time at the Plant Site is provided in Section 4.3. The recovery system wells are equipped with totalizing flow meters to record the volume of water pumped from each well. The groundwater volumes recovered to date are discussed in Section EN NWO

14 SECTION 3 Field Activities Groundwater quality samples and groundwater elevation data were collected quarterly from the Plant Site monitoring and recovery wells in March (first quarter [Q1]), June (second quarter [Q2]), August/September (third quarter [Q3]), and December (fourth quarter [Q4]) of This section summarizes the monitoring program and field activities. 3.1 Potentiometric Monitoring Prior to sampling, groundwater elevations are measured at each of the Plant Site monitoring wells relative to a surveyed top-of-casing elevation. Construction details for the monitoring and recovery wells, including water-bearing zone, ground-surface elevation, and top-of-casing elevation, are summarized in Tables 3-1 and 3-2, respectively. Table 3-1 provides quarterly groundwater elevations measured at the Plant Site monitoring wells in As shown in the table, alluvial monitoring wells UO and UO A were consistently dry throughout These wells are 15 feet deep or less, and are above the water table during normal climate conditions. Groundwater levels measured at the Plant Site recovery wells are shown in Table 3-2. Alluvium recovery well UR A was dry during September 2015; with a total depth of 25 feet, this well is the shallowest recovery well at the Plant Site. 3.2 Groundwater Sample Collection Groundwater monitoring is conducted at the locations listed in Tables 3-1 and 3-2 and shown on Figure 2-2. In 2015, the following wells, all of which are screened in the alluvium zone, were not sampled: UO in Q3; UO in Q3; UO in all quarters; UO A in all quarters; and UR A in Q3. These wells were not sampled because they were dry during the sampling period (UO , UO A, and UR A), had water levels below the bottom of the screened interval (UO ), or were pumped dry during purging and did not recharge within 24 hours (UO ). Monitoring wells are sampled using a low-flow sampling method. The first step in the sampling process is to evacuate one casing volume from the monitoring well using a dedicated bladder pump and tubing. After one casing volume has been removed, pumping continues, while temperature, ph, and conductivity are measured until the parameters stabilize. Once the field parameters are stable, the laboratory-supplied sample containers are filled directly from the dedicated sample tubing. Sample containers for dissolved metals are field filtered for laboratory analysis. The samples are filtered through a disposable 0.45-micron (µ) filter attached to the dedicated tubing, with the filtered sample discharged directly into the sample container. Each monitoring well at the Plant Site has a dedicated bladder pump and tubing, with the exception of wells UO and UO A. These two wells are sampled using dedicated bailers rather than pumps because neither well produces sufficient water to purge and sample using the low-flow method. The field technicians use the dedicated bailers to purge three casing volumes from each well. Once three casing volumes have been removed, a single set of field parameters is measured and recorded in the field data sheet. Samples are collected by pouring groundwater directly from the dedicated bailer into the laboratory-supplied sample containers. At wells UO and UO A, the filtered sample fraction is obtained by pouring groundwater into a filtering apparatus that contains a disposable 0.45-µfilter. The apparatus is pressurized using a pneumatic pump to force water through the filter and EN NWO 3-1

15 2015 ANNUAL GROUNDWATER REPORT, EVRAZ STRATCOR PLANT SITE, HOT SPRINGS, ARKANSAS into the laboratory-supplied sample containers requiring the filtered sample volume. A new filter is used at each well. The Plant Site recovery wells do not require purging before sampling, since these wells are pumped continuously. Each recovery well has a sampling port through which samples are collected. Typically, the field technician opens the sampling port and allows groundwater to flow through the sampling line for up to 5 minutes. The groundwater temperature, ph, and conductivity are then measured, and a groundwater sample is collected directly from the sampling port into the laboratory-supplied sample containers. The filtered sample fraction is collected using a disposable 0.45-µ filter threaded onto the sampling port, and is discharged directly into the laboratory-supplied containers. Once sampling at each well is complete, the samples are labeled and placed in an ice-filled cooler for shipment to the laboratory by overnight carrier for analysis. The samples are maintained under chain-ofcustody during shipment and upon receipt at the laboratory. Field duplicate samples are collected at a rate of one duplicate per 10 monitoring wells sampled. The sample collection techniques for field duplicates are the same as those used to collect the primary groundwater samples. 3.3 Laboratory Methods As specified by the Arkansas Department of Pollution Control and Ecology (ADPC&E) in a letter dated February 28, 1990, groundwater at the Plant Site is monitored for calcium, chloride, nitrate, sodium, sulfate, vanadium, total dissolved solids (TDS), ph, and specific conductance. The ph and specific conductance (i.e., conductivity) are measured in the field. Umetco has analyzed for nitrate-nitrite (as nitrogen [N]) or organic nitrogen instead of nitrate since 1998 because of the short holding time for nitrate. The 2015 quarterly groundwater samples were analyzed by Eurofins Lancaster Laboratories Environmental for the following: Dissolved metals (calcium, sodium, and vanadium) by U.S. Environmental Protection Agency (USEPA) Method Chloride by Standard Method (SM) 4500CL-E (APHA et al. 1998) Nitrogen by USEPA Method M353.2 Sulfate by USEPA Method D TDS by SM 2540C (APHA et al. 1998) 3.4 Flow Totalizers The volume of water extracted from the groundwater recovery system is measured using totalizing flow meters installed on each recovery well. The total groundwater removal volumes recovered to date are discussed in Section Operations and Maintenance Activities Nonroutine maintenance activities performed on the groundwater recovery system in 2015 included upgrading conveyance piping, installing flow meters on conveyance lines, and performing general preventative maintenance on the recovery wells in October and November EN NWO

16 SECTION 4 Results This section describes results of the 2015 groundwater monitoring at the Plant Site. 4.1 Groundwater Flow Groundwater elevations and potentiometric contours for the alluvium and Stanley Shale for December 2015 are presented on Figures 4-1 and 4-2, respectively. Groundwater elevations for December were selected for plotting because winter is typically a dry time of year at the Plant Site, resulting in lower groundwater elevations that represent hydrologic base flow conditions. During 2015, groundwater flow in both water-bearing zones was generally to the south-southeast, and was consistent with the groundwater flow directions observed during previous years. 4.2 Hydrographs Hydrographs were prepared for selected monitoring well pairs to illustrate groundwater level fluctuations since The hydrographs also show the hydraulic relationship between the alluvium and Stanley Shale. Well identification numbers ending with.1 are screened in the alluvium, while those ending with.2 are screened in the Stanley Shale. The monitoring wells shown on Figure 4-3A and Figure 4-3B were selected to compare onsite behavior with offsite conditions. Monitoring wells UO and UO are downgradient of the East Pond near the groundwater recovery system. The two wells presented for comparison, UO and UO , are approximately 1,800 ft downgradient of the effluent ponds. The water levels within the well pairings follow similar seasonal fluctuations, consistent with hydraulic connection between groundwater in the alluvium and Stanley Shale at these locations. The monitoring wells depicted on Figures 4-4A and 4-4B also show similar water level behavior between the alluvium and Stanley Shale. At wells UO and UO , the difference in water levels between the alluvium and shale is indicative of a downward hydraulic gradient near Marney Draw. Groundwater levels in wells UO and UO have historically been similar; however, periods of divergence have been observed after Finally, Figure 4-5 shows hydrographs for monitoring wells UO and UO in the northern portion of the Plant Site. This figure was included to illustrate water level changes for the upgradient Plant Site area. Groundwater levels in wells UO and UO have generally tracked together, consistent with the hydraulic connection between the alluvium and Stanley Shale in this area. 4.3 Groundwater Quality The quarterly field parameter data (ph, conductivity, and temperature) are provided in Tables 4-1 and 4-2. In 2015, field parameters measured at the Plant Site were generally consistent with previous monitoring events; however, on a network-wide scale, the range of ph values was larger than in 2014 in the alluvium and smaller in the Stanley Shale. The groundwater ph typically ranges from 4 to 7, except for the following deviations: UO B: ph values measured in 2015 ranged from 9.01 to 12.51, which are higher than the ranges observed in 2013 and 2014 (typical between 6 and 7). UO : ph in this well has consistently been between 11 and 12 since 1990; in 2015, a maximum value of was observed in this well. The ph measurements at monitoring well UO have not previously been a concern because they are localized. EN NWO 4-1

17 2015 ANNUAL GROUNDWATER REPORT, EVRAZ STRATCOR PLANT SITE, HOT SPRINGS, ARKANSAS UO : The ph was measured at in June 2015; ph readings above 11.0 have occurred at this well in the past in August 2000, November 2002, and November UO : A maximum ph value of 9.69 was measured in 2015; in 2014, a value of 9.04 was recorded, which was the highest reading in this well since August 2003 (reading of 8.96). Umetco will continue to monitoring the ph at these wells. To evaluate the structural integrity of these wells as a possible cause of elevated ph values, Umetco intends to perform an evaluation via down-hole cameras in The groundwater concentrations for each analytical parameter from each quarter are shown in Tables 4-3, 4-4, 4-5, and 4-6 for the alluvium wells; and Tables 4-7, 4-8, 4-9, and 4-10 for the Stanley Shale. Time series concentration graphs (Figures 4-6 through 4-19) for selected wells were prepared to illustrate the trends in constituent concentrations in monitoring wells completed in the alluvium and Stanley Shale. The wells were selected to provide a general indication of concentration trends in the upgradient plume area (UO and UO ); the main plume area (UO , UO , UO , and UO ); the cross-gradient area (UO and UO ); and the downgradient, offsite area (UO and UO ). The following summary of constituent concentration changes over time for the selected monitoring wells is based on a review of Figures 4-6 to For the purposes of these concentration graphs, nondetect values are shown at the detection limit. The three constituents with Target Cleanup Levels (chloride, sulfate, and TDS) are presented first. The other monitored parameters, calcium, sodium, nitrate, and vanadium, are discussed second. Additionally, isoconcentration figures for chloride, sulfate, and TDS for each zone, using data from Q4 2015, are included as Figures 4-20 through Chloride Chloride concentrations in selected alluvium monitoring wells are shown on Figures 4-6A and 4-6B; graphs are provided using a linear scale and a logarithmic scale to show changes in concentrations near the Target Cleanup Goal. Chloride concentrations from monitoring well UO (upgradient) have decreased from more than 20,000 milligrams per liter (mg/l) to less than 500 mg/l since the recovery system was installed. Chloride concentrations exceeding the Target Cleanup Goal (250 mg/l) have been more persistent at well UO (main plume area), but have decreased from a peak of more than 15,000 mg/l in 1994 to the current concentration of 4,530 mg/l. The concentrations at monitoring wells UO (downgradient), UO (cross-gradient), and UO (main plume area) are less than the Target Cleanup Goal of 250 mg/l. Chloride concentrations for selected Stanley Shale monitoring wells are shown on Figure 4-7A and 4-7B (graphs shown using linear and logarithmic scales, respectively). The decreasing chloride concentrations observed in wells UO (main plume are), UO (main plume area), and UO (upgradient) appear to have been influenced by pumping at downgradient recovery wells. The downgradient pumping has combined with the natural groundwater flow direction to draw chloride mass away from these wells. In 2015, the chloride concentration in well UO (downgradient) remained less than 250 mg/l, after decreasing to less than the cleanup level in 2014 for the first time since the early 1990s. Chloride concentrations at UO (cross-gradient), which is located west of the West Pond outside of the groundwater recovery zone, are consistently less than 250 mg/l. As shown on Figures 4-20 and 4-21, the greatest concentrations of chloride are centered around UO and UO B in the alluvium and UO and UR A in the Stanley Shale. Concentrations of chloride in the Stanley Shale are up to an order of magnitude higher than the alluvium. Compared to the data collected in Q4 2014, the area exceeding the cleanup goal in the 4-2 EN NWO

18 SECTION 4 RESULTS alluvium decreased in size due to the concentration in UO falling to less than the cleanup level. The cleanup level exceedance area in the Stanley Shale is unchanged from Q to Q Sulfate Sulfate concentrations for selected alluvium wells are shown on Figure 4-8. Sulfate concentrations in UO (downgradient), UO (cross-gradient), and UO (main plume area) have been less than the Target Cleanup Goal (250 mg/l) since monitoring began. In 1996, the sulfate concentration at UO (main plume area) began increasing before stabilizing around 500 mg/l in After achieving a historical maximum concentration in UO (upgradient) in June 2014, concentrations of sulfate in this well remained less than the cleanup level in Sulfate concentrations for selected Stanley Shale wells are shown on Figure 4-9. Sulfate concentrations in these wells are less than the Target Cleanup Goal of 250 mg/l, with the exception of monitoring well UO (main plume area). As in alluvial well UO , sulfate concentrations began increasing in well UO in 1996, but now appears to have stabilized around 500 mg/l. As shown on Figures 4-22 and 4-23, concentrations of sulfate in the alluvium are comparable to those in the Stanley Shale. In both zones, cleanup goal exceedances are limited to an area around UO and UO The area exceeding the cleanup goal decreased from 2014 to 2015 in the alluvium due to the concentration in UO falling to less than the cleanup level; additionally, the exceedance area in the vicinity of UO was smaller in 2015 due to levels in UO A and UR C falling to less than the cleanup level. In the Stanley Shale, the exceedance area decreased in 2014 to 2015 due to concentrations in UO R falling to less than the cleanup level Total Dissolved Solids TDS concentrations for selected alluvium and Stanley Shale monitoring wells are shown on Figures 4-10A and 4-10B (alluvium) and 4-11A and 4-11B (Stanley Shale). Graphs are provided using a linear scale and a logarithmic scale to show changes in concentrations near the Target Cleanup Goal. TDS concentrations are consistent in most of the alluvium monitoring wells, with the exception of well UO (upgradient), where TDS levels have decreased substantially since the early 1990s. Except for UO and UO (cross-gradient wells), TDS concentrations in these wells typically exceed the Target Cleanup Goal (500 mg/l). Monitoring wells UO and UO are located west of the West Pond outside of the groundwater recovery zone. As shown on Figures 4-24 and 4-25, the concentration distribution of TDS is very similar to that of chloride. Concentration of TDS are typically greater in the Stanley Shale then in the alluvium, but concentrations are generally on the same order of magnitude. In both zones, the exceedance area is unbounded to the north and east. The cleanup level exceedance area in both zones is unchanged from Q to Q Calcium Calcium concentrations in selected alluvium wells are shown on Figure Over the last 25 years, calcium concentrations have decreased in well UO (upgradient) from greater than 9,000 mg/l in 1990 to less than 200 mg/l in recent years. At well UO (main plume area), calcium fluctuated around a concentration of 600 mg/l before decreasing sharply in 2012 and Samples were not collected from this well in 2014 due to low water levels. During the first three quarters of 2015, levels of calcium returned to near 600 mg/l, before decreasing again to less than 200 mg/l in Q4. Calcium concentrations at monitoring well UO (main plume area) increased in the early 1990s, but have remained relatively consistent since 1997, with a slight overall decrease in concentration. Calcium concentrations at the remaining monitoring wells (UO and UO [downgradient and EN NWO 4-3

19 2015 ANNUAL GROUNDWATER REPORT, EVRAZ STRATCOR PLANT SITE, HOT SPRINGS, ARKANSAS cross-gradient, respectively]) have remained fairly consistent, with concentrations less than 300 mg/l. A sample from UO was not collected in Q due to low water levels. Calcium concentrations in selected Stanley Shale monitoring wells are shown on Figure Since the mid to late 1990s, calcium concentrations have decreased in wells UO (main plume area), UO (main plume area), and-uo (upgradient). Calcium concentrations in wells UO and UO (downgradient and cross-gradient, respectively) have remained relatively low (less than 200 mg/l) and consistent since Sodium Sodium concentrations in selected alluvium monitoring wells are shown on Figure Sodium concentrations in these wells are generally consistent, with the exception of UO (upgradient), where sodium decreased from highs between 1,000 and 2,000 mg/l during the 1990s to less than 200 mg/l over the last few years. These changes appear to be due to the influence of the recovery well capture zone of UR A and UR B in the Stanley Shale. A slight increase in sodium concentration in this well was observed in 2014, followed by an overall decrease in In monitoring well UO (main plume area), sodium began increasing from approximately 200 mg/l in 1993 before stabilizing between 800 and 1,000 mg/l in A general concentration decrease has been observed in this well since Sodium concentrations in selected Stanley Shale monitoring wells are shown on Figure Concentrations have been relatively low in UO (downgradient), UO (cross-gradient), and UO (main plume area) since monitoring began, and concentrations at UO (upgradient) have declined since Concentrations at monitoring well UO increased between 1990 and 2004, and fluctuated around 1,100 mg/l between 2004 and 2013; a slight overall decrease has been observed since Nitrate-Nitrite (as Nitrogen) Nitrate-nitrite concentrations (reported as N) have been analyzed since January 1998; prior to that time, only nitrate was analyzed. This change was made because of the short holding time of 48 hours for nitrate analysis. Figures 4-16 (alluvium) and 4-17 (Stanley Shale) show data since 1998 when the switch was made to the combined nitrate-nitrite analysis. Since 1998, nitrate-nitrite concentrations have increased in alluvium monitoring well UO (upgradient), while an overall decrease in concentrations has been observed in well UO (main plume area). Well UO experienced a historical maximum in June 2014; however, concentrations have decreased overall since that time to be consistent with levels observed from 2004 through No clear trends have been apparent in concentrations at the remaining wells in both the alluvium and Stanley Shale. Figures 4-16 and 4-17 also reveal that nitrate-nitrite concentrations are typically greater in the shallow alluvium than in the deeper Stanley Shale Vanadium Dissolved vanadium concentrations for selected alluvium and Stanley Shale wells are shown on Figures 4-18 (alluvium) and 4-19 (Stanley Shale). Dissolved vanadium concentrations in these wells are typically less than 1 mg/l, with the exception of monitoring well UO (downgradient). In the early 1990s, the vanadium concentration in UO was as high as 4.09 mg/l, but the concentration has since decreased to less than 0.5 mg/l Summary As shown on Figures 4-6, 4-7, 4-10, 4-11, 4-12, and 4-13, the concentration changes of chloride, TDS, and calcium are similar over time. These three parameters are known to be related to historical 4-4 EN NWO

20 SECTION 4 RESULTS operation of the East Effluent and Scrubber Bleed ponds. Changes in TDS concentrations are generally consistent with the changes in chloride concentrations because chloride is the predominant TDS component at the Plant Site groundwater. This dependence of TDS upon chloride concentrations explains much of the decrease in TDS concentrations observed in Stanley Shale monitoring wells UO , UO , and UO since the mid-1990s because chloride concentrations also decreased at these wells during the same timeframe. Concentration changes of sulfate and sodium are similar over time as well, as shown on Figures 4-8, 4-9, 4-14, and These parameters are known to be related to historical operations from the West Pond. The increasing sulfate and sodium concentrations observed since the beginning of monitoring to 2006 were likely caused by water leaking from the West Pond (observed in 2001 through 2002) that flushed sodium from the vadose zone before the pond was lined in April The changes in concentrations in nitrate-nitrate and vanadium are not similar to other monitored parameters. In 2015, the concentrations of chloride, sulfate, and TDS were at or less than the Target Cleanup Levels in the downgradient alluvium well UO , with the exception TDS in June In the downgradient Stanley Shale well UO , chloride was at or less than the cleanup level; sulfate was less than the cleanup level; and TDS exceeded the cleanup level. Based on the data provided herein, the following conclusions can be drawn about the overall groundwater quality at the Plant Site since monitoring began: With the exception of sulfate and sodium in UO and UO , which are located in the main plume area, concentrations of all parameters have decreased since the recovery system came online in In contrast, sulfate, and sodium in UO and UO increased into the mid-2000s and have since stabilized. Chloride, TDS, and calcium in UO have remained fairly consistent. Nitrate in UO (upgradient) has also increased over time. 4.4 Groundwater Recovery System Performance The groundwater recovery system includes 13 groundwater recovery wells and the groundwater interceptor trench (i.e., the French drain). In 2015, the recovery system pumped over 12.5 million gallons of groundwater; in 2014, approximately 13.1 million gallons were recovered. The decrease in flow rates observed in 2015 compared to recent years resulted from system downtime due to recovery system conveyance pipeline upgrades and well maintenance in the fall of Since pumping began in 1993, 232 million gallons of groundwater have been recovered, with 84 million gallons removed from the alluvium, and 148 million gallons pumped from the Stanley Shale. Figure 4-26 shows the volume of recovered groundwater per year. The groundwater recovery system was designed to address the Plant Site groundwater plumes by removing two to four pore volumes each from the alluvium and Stanley Shale. The size of one pore volume was estimated at 36 million gallons for the alluvium and 81 million gallons for the Stanley Shale in the Amended Response Plan (Umetco 1991). To date, approximately 2.3 pore volumes of groundwater have been extracted from the alluvium, and approximately 1.8 pore volumes have been removed from the Stanley Shale. These data indicate that the recovery system has achieved the minimum design goal relative to groundwater recovery in the affected plume area in the alluvium and is close to meeting the design goal in the Stanley Shale. EN NWO 4-5

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22 SECTION 5 References American Public Health Association (APHA), American Water Works Association, and Water Environment Federation Standard Methods for the Examination of Water and Wastewater. 20th ed. Baltimore, Maryland: United Book Press. Arkansas Department of Pollution Control and Ecology (ADPC&E) and Umetco Minerals Corporation (Umetco) Consent Administrative Order LIS April. B&F Engineering, Inc. 1988a. Groundwater Investigations of Paleozoic and Quaternary Formations South of Umetco/Stratcor Vanadium Facility, Hot Springs. Prepared for Umetco Minerals Corporation. Revised October 15. B&F Engineering, Inc. 1988b. Groundwater Studies at Umetco/Stratcor Vanadium Facilities Component 4. Prepared for Umetco Minerals Corporation. March. Owens, D.R., and J.S. Hollingsworth Investigation of Chloride Anomalism in Paleozoic and Quaternary Formations Underlying the Umetco Minerals Corporation Vanadium Mill and Vicinity, Garland County, Arkansas. Prepared for Umetco Minerals Corporation. June. Umetco Minerals Corporation (Umetco) Amended Groundwater Response Plan for the Paleozoic and Quaternary Formations, South of the Umetco/U.S. Vanadium Facility, Hot Springs, Arkansas. January 21. Umetco Minerals Corporation (Umetco) Annual Groundwater Report. Umetco/U.S. Vanadium Facility, Hot Springs, Arkansas. February. Umetco Minerals Corporation (Umetco) Annual Groundwater Report, Evraz Stratcor Plant Site, Hot Springs, Arkansas. March. Yancey and Associates, Inc Annual Report of Groundwater Conditions at the U.S. Vanadium Plant Site, Hot Springs, Arkansas. Prepared for Umetco Minerals Corporation. March. EN NWO 5-1

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24 Tables

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26 Table 3 1. Monitoring Well Construction Details and Measured Groundwater Elevations EVRAZ Stratcor Plant Site Hot Springs, Arkansas Umetco Minerals Corporation Well Name Mar 15 Jun 15 Aug 15 Dec 15 Mar 15 Jun 15 Aug 15 Dec 15 UO A Alluvium UO B Alluvium UO A Alluvium UO B Alluvium UO Alluvium UO Stanley Shale UO Alluvium UO Alluvium UO Stanley Shale UO Alluvium UO Stanley Shale UO Alluvium UO Stanley Shale UO Alluvium UO Stanley Shale UO Stanley Shale UO Stanley Shale UO Alluvium Dry Dry Dry Dry Dry Dry Dry Dry UO Stanley Shale UO R Stanley Shale UO Alluvium UO Stanley Shale UO Alluvium UO Stanley Shale UO Alluvium UO Stanley Shale UO A Alluvium Dry Dry Dry Dry Dry Dry Dry Dry UO B Alluvium UO Stanley Shale UO A Alluvium UO B Alluvium UO Stanley Shale UO Stanley Shale UO Stanley Shale UO B Alluvium Notes: a Screen intervals are estimated from the well boring logs ft amsl = foot above mean sea level ft bgs = foot below ground surface Water bearing Zone Ground Surface Elevation (ft amsl) Top of Casing Elevation (ft amsl) Total Depth (ft bgs) Screen Interval (ft bgs) a Water Level Measurement Groundwater Elevations EN NWO PAGE 1 OF 1

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28 Table 3 2. Recovery Well Construction Details and Measured Groundwater Elevations EVRAZ Stratcor Plant Site Hot Springs, Arkansas Umetco Minerals Corporation Well Name 3/18/2015 6/23/2015 9/29/ /7/2015 3/18/2015 6/23/2015 9/29/ /7/2015 UR B Alluvium UR C Alluvium UR D Alluvium UR E Alluvium UR B Stanley Shale UR C Stanley Shale UR D Stanley Shale UR E Stanley Shale dry dry UR A Alluvium dry dry UR A Stanley Shale UR A Stanley Shale UR A Stanley Shale UR B Stanley Shale Notes: a Screen intervals are estimated from the well boring logs ft amsl = foot above mean sea level ft bgs = foot below ground surface Water bearing Zone Ground Surface Elevation (ft amsl) Top of Casing Elevation (ft amsl) Total Depth (ft bgs) Screen Interval (ft bgs) a Water Level Record Quarterly Groundwater Elevations EN NWO PAGE 1 OF 1

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30 Table Groundwater Field Parameter Results Measured in the Alluvium EVRAZ Stratcor Plant Site Hot Springs, Arkansas Umetco Minerals Corporation Field Conductivity Well Number Sampling Date (µmhos/cm) Field ph (s.u.) Temperature ( C) UO A UO B UO A UO B UO UO UO UO UO UO /25/ /17/ /31/ /10/ /25/ /17/ /31/ /10/ /24/ /12/ /27/ /11/ /24/ /12/ /27/ /11/ /26/ /22/ /31/ /16/ /25/ /16/ Q3 12/16/ /25/ /19/ Q3 Not Sampled Not Sampled 12/9/ /23/ /17/ /26/ /10/ /1/ /12/ /27/ /10/ /25/ /19/ /1/ /16/ EN NWO PAGE 1 OF 3

31 Table Groundwater Field Parameter Results Measured in the Alluvium EVRAZ Stratcor Plant Site Hot Springs, Arkansas Umetco Minerals Corporation Field Conductivity Well Number Sampling Date (µmhos/cm) Field ph (s.u.) Temperature ( C) Q1 Not Sampled UO Q2 Not Sampled Q3 Not Sampled Q4 3/27/ Not Sampled UO /22/ /4/ /17/ /24/ UO /15/ /28/ /15/ /24/ UO /15/ /28/ /15/ Q1 Not Sampled UO A Q2 Not Sampled Q3 Not Sampled Q4 3/23/15 77 Not Sampled UO B 6/11/ /25/ /11/ /26/ UO A 6/22/ /4/ /17/ /24/ UO B 6/11/ /25/ /15/ /25/ UO B 6/16/ /28/ /16/ /20/ UR B 6/18/ /2/ /18/ EN NWO PAGE 2 OF 3

32 Table Groundwater Field Parameter Results Measured in the Alluvium EVRAZ Stratcor Plant Site Hot Springs, Arkansas Umetco Minerals Corporation Field Conductivity Well Number Sampling Date (µmhos/cm) Field ph (s.u.) Temperature ( C) UR C UR D UR E UR A Notes: C = degree Celsius µmhos/cm = micromhos per centimeter NR = not recorded Q3 = third quarter s.u. = standard unit 3/20/ /18/ /2/ /18/ /20/ /18/ /2/ /18/ /20/ /18/ /2/ /18/ /27/ /23/2015 NR Q3 Not Sampled 12/17/ EN NWO PAGE 3 OF 3

33 Table Groundwater Field Parameter Results Measured in the Stanley Shale EVRAZ Stratcor Plant Site Hot Springs, Arkansas Umetco Minerals Corporation Well Number UO UO UO UO UO UO UO UO UO R UO Sampling Date Field Conductivity (µmhos/cm) Field ph (s.u.) Temperature ( C) 3/26/15 out of range /22/ /31/ /16/ /23/ /16/ /26/ /9/ /23/ /17/ /26/ /10/ /19/ /12/ /27/ /10/ /26/ /19/ /1/ /16/ /24/ /17/ /26/ /10/ /25/ /12/ /27/ /11/ /24/ /16/ /28/ /11/ /19/ /10./ /24/ /8/ /26/ /22/ /1/ /17/ EN NWO PAGE 1 OF 3

34 Table Groundwater Field Parameter Results Measured in the Stanley Shale EVRAZ Stratcor Plant Site Hot Springs, Arkansas Umetco Minerals Corporation Well Number UO UO UO UO UO UO UR B UR C UR D UR E Sampling Date Field Conductivity (µmhos/cm) Field ph (s.u.) Temperature ( C) 3/24/ /15/ /28/ /15/ /24/ /15/ /28/ /15/ /23/ /11/ /25/ /11/ /24/ /11/ /25/ /15/ /19/ /10/ /24/ /8/ /23/ /19/ /27/ /8/ /20/ /18/ /2/ /18/ /20/ /18/ /2/ /18/ /20/ /18/ /2/ /18/ /20/ /18/ /2/ /18/ EN NWO PAGE 2 OF 3

35 Table Groundwater Field Parameter Results Measured in the Stanley Shale EVRAZ Stratcor Plant Site Hot Springs, Arkansas Umetco Minerals Corporation Well Number UR A UR A UR A UR B Notes: C = degree Celsius µmhos/cm = micromhos per centimeter s.u. = standard unit Sampling Date Field Conductivity (µmhos/cm) Field ph (s.u.) Temperature ( C) 3/27/ /23/15 NR /4/ /17/ /27/ /23/ /1/ /16/ /27/ /23/15 NR /1/ /16/ /27/ /23/ /01/ /17/ EN NWO PAGE 3 OF 3