March 16, 2009

Tetra Tech, Inc. Project No. 112C01527

Ms. Robyn Gross Alcoa Inc. 201 Isabella Street Pittsburgh, PA 15212 Subject: Alcoa Bauxite Residue Disposal Area (RDA)

Summary Report - Seepage Control Investigation Bauxite, Arkansas

INTRODUCTION Tetra Tech NUS, Inc. (Tetra Tech) has prepared this Seepage Control Investigation Summary Report for the Bauxite Residue Disposal Area (RDA) located in Bauxite, Arkansas (Figure 1). This report summarizes the results of investigations which included, test borings, piezometer installations (shallow and deep), surface water quality measurements, hydrologic monitoring, aquifer testing and groundwater sampling. The purpose of this investigation was to identify whether surface water and groundwater were being impacted by RDA seepage on the south side of the RDA, and if so, to evaluate the feasibility of an interception and conveyance system to prevent further impacts and migration. This investigation was conducted due to the discovery of alkaline groundwater seepage at the haul road underpass 1500 feet south of the RDA. SITE BACKGROUND The entire Alcoa Bauxite, Arkansas property (Property) (Figure 1) consists of an approximate 12,000-acre parcel of land located in Saline County, Arkansas. The investigation area (Site) is immediately south of the RDA and occupies an approximate 250 acres. The Site is located north of Arkansas Highway 183 (also called Reynolds Road) in Bauxite, Arkansas, and east of the City of Benton. Bauxite was mined from areas on the Property and refined into alumina. Waste material from the refining process was slurried into RDA impoundments. The refining process utilizes sodium hydroxide to remove alumina material from the ore; therefore the waste material is alkaline in nature. The RDAs at the site were last used in 1990. They were capped with clay and vegetated in 2001. Although most rainfall runs off the RDA as storm water, a portion of it infiltrates the RDA surface. As the water infiltrates the RDA, it takes on properties of the waste material. This alkaline liquid is known as bauxite residue leachate (BRL).

Ms. Robyn Gross March 16, 2009 Page 2 BRL from the RDA is collected and conveyed in a series of ditches to a surface water impoundment (the former “Swamp Poodle” mine pit) about a mile to the south. The BRL impacted water is treated (pH neutralization and settling) and discharged to Holly Creek under an NPDES discharge permit. On the north side of the RDAs a subsurface drain within the RDAs aids in the collection of the BRL. On the south side, BRL discharges from the toe of the dike to a ditch that runs to the Swamp Poodle mine pit. Investigations were initiated in 2006 after it was discovered that alkaline groundwater was discharging at the haul road underpass 1500 feet south of the RDA, suggesting some BRL was flowing under the ditch along the south toe of the RDA. INVESTIGATION The following tasks were completed as part of this investigation:

1. Inventory of BRL drainage ditches over a 140 acre area south of the RDAs.

2. Investigate subsurface conditions along a 2500 ft stretch of the southern toe of the RDA to support design of a BRL interceptor drain.

3. Investigate potential BRL impacted groundwater in three specific areas (Figure 2) identified in previous terrain conductivity survey:

Area 2: North of property line about 700 ft west of existing well P-701.

Area 3: North of property line about 700 ft west of existing well P-301/P-601.

Area 4: South of property line at the North end of Swamp Poodle pond.

4. Develop a preliminary design and cost estimate for a BRL interceptor and conveyance system. Note that the design and cost estimate is reported separately.

5. Install groundwater recovery wells at Area 2, including:

o Hydraulic testing at the first recovery well

o Installation of 3 additional recovery wells.

Surface Water Conditions South of the RDAs

To characterize the nature and characteristic of surface flows off the RDAs and in the surrounding ditch system and their possible impact to groundwater, approximately 35,000 feet of ditches were surveyed to determine flows volumes, chemical characteristics and head relationship with shallow groundwater. As part of this effort seventeen (17) monitoring stations were established along the drainage ditches as shown in Figure 3. For the purpose of classification the drainage system was divided into three distinct segments, labeled Segment A, B and C.

Flow measurements were obtained at surface water monitoring locations. Surface water quality data including specific conductivity, pH, temperature and stream flow data were also measured. This data was collected during two events, June 5-7, 2007 and May 11-12, 2008. Manometers were also installed at each location to measure the head

Ms. Robyn Gross March 16, 2009 Page 3 differential between the surface water in the stream and the groundwater immediately beneath the channel, providing an indication of whether the stream is losing or gaining water. Data collected during these two events are summarized in Table 1.

Subsurface Conditions along the Southern Toe of the RDA to Support Design of a BRL Interceptor Drain Twelve test borings (B-1 to B-12) were originally drilled during June and July, 2007 to characterize soil and shallow groundwater conditions at the southern toe of the RDA, as shown on Figure 3. The borings were advanced through silty sands to the top of the lignitic silt and clay layer (lignite). During May and June of 2008, seven additional borings (B-13 to B-19) were advanced south of the power lines oriented from east to west along the toe of the RDA to the top of the lignite to define subsurface conditions in this area. Based on the soil and groundwater boring data, the lignite layer is a continuous and prominent confining layer at the site. Piezometers were installed with screens within the sands immediately above the lignite to help characterize shallow groundwater conditions at the original boring locations B-1 through B-12. At two locations (B-3D and B-8D) an additional piezometer was installed below the lignite in a separate deep sand. Following piezometer installation, water levels in the piezometers were measured to determine flow units and direction of flows. Table 2 presents a summary of all the piezometer installation details. Appendix A contains boring logs, piezometer construction details and recovery well details. Standard penetration tests (SPT) were performed continuously at each borehole. Soil samples were visually examined, photographed, and logged. Samples were selected from each boring for physical testing which will include grain-size analysis, moisture content, and Atterberg Limits. Permeability testing was performed on samples taken from the lignite layer. Measurements of soil pH were obtained from the borings to identify soil units impacted by BRL. Investigation of Potential BRL Impacted Areas Identified by Terrain Conductivity Survey To characterize the groundwater flow units at the Site within the three suspect areas identified by a previous terrain conductivity survey, a total of ten piezometers were installed. As a result, two separate groundwater units, shallow and deep, were identified during soil sampling and piezometer installation. The unconfined shallow groundwater unit is typically less the 30 feet below ground surface with 10 to 20 feet of saturated thickness above the lignite layer. The contour map of the top of the lignite layer between the two groundwater units is depicted on Figure 4. The deep, confined groundwater unit below the lignite was encountered 45 feet to 80 feet below ground surface. Further to the south of the RDA in the vicinity of Swamp Poodle Pond where the lignite layer is absent, this deep unit is semi-confined. To characterize the shallow groundwater flow unit, 3 piezometers (P-5S, P-6S, and PZ-1) and one recovery well (RW-1) were installed to the top of the lignite layer during June and July of 2007. Three additional recovery wells RW-2, RW-3 and RW-4 were installed

Ms. Robyn Gross March 16, 2009 Page 4 during May and June of 2008. Soil samples at the piezometers and the groundwater extraction wells were collected on 5-foot intervals. To characterize the deep groundwater flow unit at the site, six deep piezometers (P-1, P-2, P-4, P-5D, and P-6 D, P-8) were installed at locations shown in Figure 2. For all but P-8, drilling was completed at each location to a depth of 100 feet with soil samples collected every 5 feet. Following drilling and sampling, the deep boreholes were logged with down-hole geophysical equipment. Based on the review of the geophysical data and soil sampling data, piezometer screen units were selected. Water levels in the piezometers were measured to determine flow units and direction of flows. Groundwater from several of the piezometers was sampled and tested. The samples were analyzed for general water quality parameters and those to assist in detection of BRL including select metals, anions, bromide (Br), chloride (Cl), fluoride (F), nitrate (NO3) and sulfate. Each groundwater sample was analyzed for total alkalinity. To characterize the potential to collect and contain BRL impacted groundwater from the shallow groundwater unit in Area 2, a single four (4) inch diameter recovery well (RW-1) was installed at the location shown on Figure 2 during June and July 2007. A step test and 3 day pumping test was performed to determine formation hydraulic parameters to prepare a design and estimated cost for a groundwater recovery system adequate to intercept the BRL discovered in this Area 2. Aquifer response to pumping was determined by monitoring water levels in PZ-1, P-5S, P-6S and RW-1 with pressure transducers. Flow rates were monitored continuously throughout the aquifer test using a digital flow meter. Water level data collected during the pumping test was analyzed using software to determine aquifer hydraulic parameters. Additionally, one week of continuous groundwater level monitoring was conducted in selected deep piezometers to determine if the deep groundwater flow unit is influenced by any off-site or nearby groundwater pumping. Three piezometers P-2, P-5 and P-8, were selected for this monitoring based on their positions located along the western property lines of the site. In addition, a pressure transducer was installed at the staff gauge in Swamp Poodle to monitor surface water trends and to determine if the water level in Swamp Poodle had an effect on water levels in P-8. Based on the results of the aquifer testing and operation of RW-1, additional recovery wells RW-2, RW-3 and RW-4 were installed in Area 2 during May and June of 2008. DATA OBTAINED Soil Conditions Test borings performed at the site encountered three distinct soil units. From the ground surface downward, these units include silty, yellow tan fine sand that ranges from 17 feet to 52 feet thick. At the base of this layer is in 6 to 12 inch thick gravel layer. Below that unit is a lignite unit consisting primarily of a dark brown organic silt and clay with interspersed layers of fine sand. This lignite unit ranges in thickness from 20 the 38 feet thick. Geotechnical testing results of undisturbed Shelby tube samples of this material

Ms. Robyn Gross March 16, 2009 Page 5 resulted in a permeability of approximately 1 x 10-8 cm/sec. Beneath the lignitic layer is a unit of grey to yellow silty fine to very fine sand. This unit is variable in thickness across the site but is at least 30 feet thick in places.

Soil pH Conditions

Soil pH values were measured in all the piezometer borings and recovery wells. These pH measurements provide an indication of BRL impact. All samples obtained from the lignite unit and the lower groundwater zone displayed neutral to slightly acidic conditions. Soils in the upper units displayed different conditions based on the boring location. Soil samples from borings in Area 3 and Area 4 (P-1, P-2 and P-4) generally showed no indications of BRL impact. Soil samples from borings in Area 2 showed impact from BRL above the top of the lignite. Soil samples along the toe of the RDA had mixed results. Soil samples from Borings B-1, B-2 and B-3 located on the west side of the RDA exhibited elevated soil pH values in the upper ten to fifteen feet of the borings, related to infiltration of BRL impacted surface water. Soil samples from B-1, B-2, B-3, B-4 and B-13 from fifteen feet to the top of the lignite zone had pH values ranging from 7 to 5. P-301 (Figure 2) is a shallow piezometer located directly south (downgradient) of B-1, B-2 and B-3. The pH of groundwater from P-301 does not indicate impact from BRL. Soil samples from the upper soil units in B-5 through B-10 and B-14 through B-19 showed impact from BRL from the water table to the top of the lignite. The estimated limits of BRL impacted subsurface soils above the lignite as indicated by the soil pH measurements are shown on Figures 5 and 6.

Groundwater Sample Analytical Results (Shallow and Deep) Tables 3 and 4 summarize filtered groundwater sample analytical results from piezometers screened in the shallow and deep groundwater flow unit. Specific analytical parameters which exceeded primary or secondary MCLs appear in bold print. Groundwater from the three shallow wells P-5S, P-6S and RW-1 in Area 2 exhibit BRL impacts. The pH of the groundwater is approximately 12 in each well and the total alkalinity values are up to 14.4 gram / liter (g/l), about half that of BRL which ranges from 20 g/l to 30 g/l. Electrical conductivity suggest total dissolved solids (TDS) are about half that of seawater. Sodium / chloride ratios are elevated (up to 22) with respect to a more typical ratio of sodium chloride salt (0.6). The excess sodium in BRL is due to the sodium carbonate / hydroxide present in the residue. The high dissolved silica in the groundwater is also indicative of BRL as silicate mineral matter can be dissolved by high strength BRL. Also, Aluminum (Al), Molybdenum (Mo), Fluoride (F), Arsenic (As), Iron (Fe), Sulfate (SO4), Selenium (Se), Vanadium (Va) and Mercury (Hg) concentrations exceed the federal drinking water MCLs.

Ms. Robyn Gross March 16, 2009 Page 6 The deep groundwater zone does not indicate clear BRL impacts. The lignite layer separating the shallow and deep groundwater units apparently acts as a barrier to deeper RDA groundwater flow as the deep groundwater wells have a very different chemistry much closer to anticipated background water quality. The only potential evidence of BRL groundwater impacts are sodium and silica. Sodium is elevated with respect to chloride with ratios up to 7; however the highest value of sodium (P-1) is only about 30 ppm and this may still be in the range of background. Silica appears elevated with respect to the other deep piezometers in P-4; however again it’s not clear what the background range may be in this deep unit. Groundwater in the deep unit appears to be of naturally poor quality for potable purposes due to iron and manganese which are elevated above secondary MCLs likely as a result of the organics in the lignite layer keeping Eh (redox potential) low and therefore increasing the solubility of these naturally occurring parameters. Shallow Groundwater Flow Zone The depth to groundwater was measured at each monitoring well location on August 1, 2007 and May 12, 2008. The corresponding groundwater elevations were calculated for the piezometers screened in the shallow flow unit. Figures 5 and 6 are shallow groundwater flow unit contour maps based on the August 1, 2007 and May 12, 2008 data. Groundwater flow in the shallow unit during these two periods was toward the southeast with a hydraulic gradient of 0.021 and 0.025 throughout the Site area. The shallow groundwater flow unit is discontinuous towards the southern portion of the site. The groundwater flow in the shallow unit correlates well with the surface of the lignite layer. However, groundwater flow in the shallow flow unit is likely controlled by discharge to surface water along stream segment A and also by seeps associated with the outcrop of the lignite layer along the west slope of the haul road underpass immediately north of Arkansas Route 183. Shallow groundwater flow in the southwest corner of the RDA also appears to be influenced by the topographic high immediately to the west. Based on groundwater elevation data and in-stream manometer data, groundwater from the shallow flow unit discharges to stream segment A south of the RDA, especially in the vicinity of SW-9. Water collected in the underpass sump, located in the southwest corner of the haul road – Highway 183 underpass, has been reported by Alcoa to be alkaline. The alkaline water collected at this sump is conveyed to Swamp Poodle for treatment. Based on the step drawdown test, the 72-hour aquifer test at well RW-1 was performed at a rate of 2.08 gallons per minute. Transmissivity (T) and storativity (S) values were determined from the pumping using methods by Theis (1935), Cooper-Jacob (1946), and Neuman (1974) with enhancements by Moench (1993, 1996). The following table summarizes T and S estimates:

Method T S

Theis 396 Ft2/Day 0.88

Neuman 415 Ft2/Day 0.88

Cooper-Jacob 426 Ft2/Day 0.88

Ms. Robyn Gross March 16, 2009 Page 7 The groundwater capture zone of approximately 110 to 120 feet radius for the pumping well at approximately 2.1 gpm was determined using graphical methods by Theis and Neuman. Deep Groundwater Flow Unit Groundwater elevation measurements for the deep groundwater flow unit were measured on August 1, 2007 and May 12, 2008. Groundwater elevation within the deep groundwater flow unit were found approximately 35 to 40 feet lower than those in the shallow groundwater flow unit clearly indicating the lignite layer separating the units acts as an aquitclude. Figure 7 is a deep groundwater flow unit contour map representative of conditions in the deep unit for the August 1, 2007 and May 12, 2008 measurements. Groundwater flow in the deep flow unit was toward the southeast with a hydraulic gradient of 0.0043. The deep flow unit wells are screened in a sand unit below the lignitic silt and clay layer. The deep groundwater flow unit is a confined unit north of Arkansas Highway 183 and a semi-confined unit in the area around Swamp Poodle based upon the stratigraphy of the site and observed responses to barometric pressure. Discharge from this unit locally is to the Swamp Poodle mine pit. Figures 8, 9, and 10 are hydrographs of the groundwater elevations in P-2, P-5, P-8 between July 15 and July 22, 2007 plotted with barometric pressure measurements over the same time period. Barometric pressure measurements taken at the Little Rock, Arkansas airport were obtained from the National Oceanic and Atmospheric Administration (NOAA). The hydrographs show small fluctuations in groundwater elevation corresponding to changes in barometric pressure. There were no apparent trends observed in the hydrographs that were indicative of influences from groundwater pumping. The hydrograph of P-8 (Figure 10) located approximately 100 feet north of Swamp Poodle compares well with Figure 11, the hydrograph from Swamp Poodle which is a former bauxite mining pit. Two increases in the water levels in the piezometer were recorded on July 16 and July 19, which correspond to precipitation events that influenced the surface water level in Swamp Poodle. The two increases in the water levels in response to the precipitation events that occurred on July 16 and July 19 are visible in both hydrographs. The Swamp Poodle hydrograph did not display any changes in water elevation corresponding to changes in barometric pressure as would be expected. Hydrograph data from P-8 and Swamp Poodle indicate a hydraulic connection between the deep groundwater unit monitored by P-8 and the surface water in Swamp Poodle. Surface Water Based on pH and specific conductivity measurements, Segment A which flows south from the RDA has been impacted by BRL. Segment B is slightly impacted by BRL as evidenced by elevated pH measurements and slightly elevated conductivity measurements. Based on pH and specific conductivity measurements at the monitoring point for segment C, this stream does not appear to be impacted by BRL.

Ms. Robyn Gross March 16, 2009 Page 8 Based on flow measurements and manometer readings taken June 5-7, 2007 and May 12, 2008, the drainage ditches have a complex and variable relationship with shallow groundwater. Segment A initially gains BRL impacted groundwater along the toe of the RDA but then loses much of this flow to shallow groundwater as it heads south. There is a large drop in elevation between monitoring points 8 and 9 on segment A. At point 9 the elevation of the ditch is at or below the top of the lignite layer, fully intercepting any groundwater in the shallow unit. Surprisingly flow is not seen to increase significantly until point 11 at which point segment B flow has joined segment A. Much of this stream flow is then lost to groundwater by the next monitoring point 14. CONCLUSIONS Groundwater Units Two distinct water bearing units were identified, a shallow and deep flow unit. Both units are separated by a continuous lignitic silt and clay unit exhibiting a low vertical hydraulic conductivity limiting the potential for vertical migration of impacted groundwater from the shallow flow unit to the deep flow unit. Shallow Groundwater The shallow flow unit flows towards the south and southeast with discharge to streams and at seeps north of State Route 183 along the haul road underpass. The shallow groundwater flow is controlled by discharge to surface water at low points in the surface topography and at areas where the lignite layer outcrops. Groundwater in piezometers in Area 2 from the shallow flow unit exceeds MCLs and secondary MCLs for the following parameters; aluminum, arsenic, iron, selenium, mercury, chloride, fluoride, sodium and sulfate. Deep Groundwater Groundwater below the lignitic layer does not appear to be significantly impacted by BRL. The deep groundwater flow unit flows towards the southeast. Groundwater in select piezometers from the deep flow unit exceeds secondary MCLs for iron and manganese, likely due to natural factors, which would make the water a poor source of potable water. Hydrologic monitoring of piezometers screened in the deep flow unit does not indicate that this unit is under the influence of nearby groundwater withdrawal. The hydrologic monitoring of the staff gauge in Swamp Poodle does indicate a hydraulic connection between the surface water body (Swamp Poodle) and P-8.

Ms. Robyn Gross March 16, 2009 Page 9 Current Surface Water Conditions Surface water monitoring in stream segments A, B and C, downgradient of the RDA indicates that BRL has impacted segment A and to a less extent segment B. Segment C does not appear to be impacted by BRL. This information supports a conclusion that impacted groundwater is discharging at topographic low points at the haul road underpass and along stretches of surface drainage north of State Route 183. Collection and Containment of BRL Impacted Groundwater Based on this investigation, engineering facilities can be used to collect impacted shallow groundwater and convey it for treatment. The use of trench drains can be considered where higher anticipated flows are expected and where the top of the lignite layer is reasonably accessible with standard excavation equipment. Groundwater extraction wells RW-1 through RW-4 have been installed and are successfully operating along the property line in Area 2 to prevent off-site migration of BRL impacted shallow groundwater. Once BRL is intercepted, conveyance by pipe to the Swamp Poodle impoundment for treatment will allow for gradual recovery of the effected drainage channel. CLOSING If you have any questions regarding this submittal, please do not hesitate to contact me at 412-320-2220 with any questions. Sincerely, Tetra Tech

Biff Cummings P.E. Project Manager Attachments cc: Mr. Peter Swallow, Alcoa Inc. Mr. Kirk Gribben, Alcoa Inc. Mr. Patrick Keogh, Alcoa Inc. Mr. James Ferguson, Tetra Tech

Tables

TABLE 1

Surface Water Quality Data / Stream Flow Data At Manometer / Surface Water Monitoring Points

Alcoa Bauxite RDA Investigation Bauxite, Arkansas

Specific

Conductivity uS/cm

pH Depth (ft.) Flow (fps)

Manometer Depth to Water (ft.)

(outer/inner)

Manometer / Monitoring Point

/ Segment

Monitoring Point / Lignite

Elevation

Gaining or Losing Point

6/7/07 5/11/08 6/7/07 5/11/08 6/7/07 5/11/08 6/7/07 5/11/08 6/7/07 5/11/08

1 (A) 388.89/377 Losing 41,218 32,020 12.57 12.89 0.6 0.65 0.13 0.15 1.50/1.44 1.45/1.42

2 (A) 377.73/365 Neutral/Lose 30,074 26,880 12.29 12.63 0.25 .20 0.06 0.11 1.63/1.63 2.10/2.01

3 (A) 363.67/358 Neutral 38,407 38,204 12.50 12.46 0.6 0.62 0.02 0.11 2.25/2.25 2.11/2.11

4 (A) 360.36/354 Neutral 34,307 35,124 12.39 12.94 0.37 0.40 0.04 0.25 1.57/1.60 1.50/1.48

5 (A) 355.84/352 Lose 40,276 41,274 12.43 12.90 0.45 0.53 0.02 0.5 1.50/1.41 1.45/1.25

7 (A) 357.92/346 Gaining * 38,143 * 12.85 0.02 * * * 1.71/1.90 1.85/2.35

8 (A) 350.42/345 Neutral 31,933 32,802 12.16 12.59 0.10 0.25 0.04 0.41 1.65/1.64 ****/****

9 (A) ------/WO Neutral /

Lose 18,067 19,200 12.21 12.76 0.30 0.32 0.03 0.44 1.81/1.79 1.8/1.5

10 (B) 337.08/ WO Gaining 1,860 *** 9.93 0.30 *** 0.05 *** 3.02/3.34 ***

11(A) 336.29/ WO Gain/Neutral 22,716 22,010 12.8 12.67 0.20 0.35 0.22 2.50/2.80 2.30/2.29

12 (B) 344.77/ WO Gaining 1,853 1,786 9.73 10.06 0.30 0.54 0.25 0.39 1.33/1.40 0.95/0.95

13** (B) 360.92/ WO Neutral 3,081 Dry 10.17 Dry 0.25 Dry 0.00 Dry 1.88/1.85 Dry

14(A) 330.88/ WO Neutral 10,190 10,199 12.03 12.67 0.04 1.46 0.09 0.56 1.50/1.53 0.45/****

15 (C) 331.73/ WO Lose/neutral 464 347 7.31 6.38 0.30 0.7 0.02 0.3 1.96/2.04 1.96/1.96

16 (A) 328.13/ WO Losing 7,206 7,654 11.88 12.64 0.50 *** 0.22 0.5 1.41/1.39 ***

17 (A) 326.00/ WO Gaining 4,914 6,015 11.54 12.41 0.45 0.50 0.11 0.82 2.56/3.08 2.45/2.60

SG 319.71/ WO Losing 3,004 *** 11.06 *** 0.50 *** 0.03 *** 0.25/3.01 ***

Note: 1. * - Insufficient volume of water to obtain surface water quality or flow measurements. 2. ** No flow at manometer during June 5th-7th monitoring event. Data from June 26th event. 3. *** SG, SW-16, SW-10 – Staff gauge washed out of place during May 12, 2008 event. 4. **** Manometer filled with silt due to flooding. 5. Manometer outer and inner water level changes less than or equal to 0.03 feet are considered neutral. 6. WO – Within outcrop area of lignitic silt and clay. Elevations of lignite at SG points interpolated from lignite structure contour map.

Table 2

Piezometer and Recovery Well Installation Details

Alcoa RDA InvestigationBauxite, Arkansas

Piezometer ID Northing EastingGround

ElevationTop of PVC

(Elev)PVC

Stickup

Total Borehole

Depth

Total Piezometer

Depth

Top of Screen (BGS)

Top of Screen (Elev)

Bottom of Screen (BGS)

Bottom of Screen (Elev)

B-1 22982.82 8325.66 406.14 409.02 2.88 30 28 18 388.14 28 378.14B-2 22997.45 8697.90 403.02 406.73 3.71 30 24 14 389.02 24 379.02B-3S 22808.80 8850.15 394.91 397.37 2.46 16.5 16 6 388.91 16 378.91B-3D 22805.34 8839.30 395.24 398.3 3.06 54 54 44 351.24 54 341.24B-4 22916.90 9026.18 398.62 409.91 11.29 27 25 15 383.62 25 373.62B-5 22917.25 9025.55 398.62 402.38 3.76 21 20 10 388.62 20 378.62B-6 22920.49 9426.38 392.35 396.14 3.79 19.5 19 9 383.35 19 373.35B-7 22878.46 9681.06 385.28 389.07 3.79 15 14 4 381.28 14 371.28B-8s 22925.56 9943.04 387.13 389.65 2.52 21 20 10 377.13 20 367.13B-8d 22926.98 9953.56 387.48 390.24 2.76 68 68 58 329.48 68 319.48B-9 22801.01 10381.30 380.33 384.44 4.11 30 21 11 369.33 21 359.33B-10 22864.60 10691.01 375.63 378.7 3.07 19.5 19.5 9.5 366.13 19.5 356.13B-11 22883.49 10945.15 388.24 390.75 2.51 34.5 34 24 364.24 34 354.24B-12 23053.89 11302.63 442.75 445.62 2.87 54 52 42 400.75 52 390.75

P-1 23736.97 7178.80 439.08 441.68 2.6 102 90 80 359.08 90 349.08P-2 23137.28 7325.05 434.07 436.64 2.57 102 100 90 344.07 100 334.07P-4 22300.53 9118.82 405.43 407.86 2.43 102 87.5 77.5 327.93 87.5 317.93P-5S 21681.61 9823.37 370.94 373.64 2.7 26 26 16 354.94 26 344.94P-5D 21682.77 9834.28 372.6 375.63 3.03 102 85 75 297.6 85 287.6P-6S 21890.02 10175.00 371.16 373.84 2.68 24 24 14 357.16 24 347.16P-6D 21890.02 10175.00 370.84 373.48 2.64 102 80 70 300.84 80 290.84P-7 (boring)* 20418.40 10248.90 --- --- --- --- --- --- --- --- ---P-8 19931.78 10462.86 337.09 339.81 2.72 60.25 45 35 302.09 45 292.09

RW-1 21700.83 10037.83 372.12 374.37 2.25 29.35 29.35 4.35 367.77 29.35 342.77RW-2 21765.05 10003.20 372.51 375.18 2.67 35 35 15 357.51 35 337.51RW-3 21685.12 9845.14 373.24 377.42 4.18 27 27 7 366.24 27 346.24RW-4 21740.25 9738.38 370.7 373.74 3.04 25 25 5 365.7 25 345.7PZ-1 21704.73 10023.95 373.4 376.68 3.28 30 30 20 353.4 30 343.4

Residue Disposal Area Piezometers

P-Series Piezometers

Recovery Wells

Table 3Shallow Groundwater Flow Zone Analytical Data

Alcoa RDA InvestigationBauxite, Arkansas

RW-1 P-5S P-6S

MCL RL Result Result Result200ug/L* 200ug/L 1860 B,J 10600 326010ug/L 10ug/L 672 654 1200

---- 200ug/L 3700 4040 5390---- 5000ug/L 3350 B 1680 B 280 B

1000ug/L* 25.0ug/L 14.6 B 40.8 B 5.5 B300ug/L* 100ug/L 638 B,J 21400 1220

---- 5000ug/L ND ND 980 B---- 5000ug/L ND 252 B ND

50ug/L* 15.0ug/L ND 24.3 B 2.5 B---- 40.0ug/L 6490 4950 8390---- 5000ug/L 6180000 5840000 3870000

50ug/L 5.0ug/L 372 245 373---- 500ug/L 4890000 139000 1230000---- 50.0ug/L 859 J 1030 766

500ug/L* 20.0ug/L 82.8 B 33.3 B 19.4 B2ug/L 0.20ug/L 4.2 2.4 6.9

---- 0.0050ug/L 0.0010 B 0.0022 B 0.16---- 0.0050ug/L 0.0084 0.0062 0.22

---- 0.20 mg/L ND G 0.75 B 0.65 B250mg/L* 1.0 mg/L 275 271 3182.0mg/L* 0.050 mg/L 35.3 38.4 50.610mg/L 0.050 mg/L ND G ND G 0.94

250mg/L* 1.0 mg/L 1100 850 1110---- 5.0 mg/L 14400 J 7060 10800

pH 12.07 11.99 12.12Specific Conductivity 20192 17522 17551Temperature 18.12 18.54 18.98ORP -503 -44 -50Dissolved Oxygen 0.02 0.01 0.01

25.9 >1000 28

RL = Reporting limit.

Bold values indicate paramater exceeding MCL or secondary MCL.

ppmNTUs

Field ParametersUnits---

uS/cmCelcius

Well ID:Metals

Gallium:Tungsten:

Aluminum:

Manganese:

Selenium:Silicon:Vanadium:Zinc:

Constituents:

Arsenic:

Bromide:Chloride:

Magnesium:

Molybdenum:Sodium:

Anions

Copper:Iron:

Sulfate:

Turbidity

B= Estimated result. Result is less than RL.

J= Method blank contamination. The associated method blank contains the target analyte at a reportable level.

Groundwater Quality ParametersTotal Alkalinity:

Parameter

mV

Fluoride:Nitrate as N:

Boron:

*= Secondary MCL

Mercury:

Potassium:

Calcium:

Table 4

Deep Groundwater Flow ZoneAnalytical Data

Alcoa RDA InvestigationBauxite, Arkansas

P-1 P-2 P-4 P-5D P-6D P-8

MCL RL Result Result Result Result Result Result200ug/L* 200ug/L 11.2 B 138 B 18.0 B 28.2 B 21.8 B ND10ug/L 10ug/L ND ND ND ND ND ND

---- 200ug/L 21.2 B,J 7.2 B,J 23.6 B,J 23.6 B,J 41.0 B,J 79.0 B,J---- 5000ug/L 7950 J 8030 10600 3970 B 10300 44500 J

1000ug/L* 25.0ug/L 0.98 B ND ND ND ND ND300ug/L* 100ug/L 881 6380 4920 1190 1020 41300

---- 5000ug/L 1430 B 1980 B 1890 B 1380 B 1730 B 4620 B---- 5000ug/L 1740 B 4070 B 3290 B 1480 B 1740 B 12200

50ug/L* 15.0ug/L 52 62.4 110 28.1 67.7 509---- 40.0ug/L ND ND 2.2 B,J ND ND ND---- 5000ug/L 29600 5630 24400 11100 26500 19800

50ug/L 5.0ug/L ND ND ND ND ND 3.6 B---- 500ug/L 11100 9020 J 4890000 13300 J 9890 J 7310---- 50.0ug/L ND ND ND ND ND ND

500ug/L* 20.0ug/L 11.7 B,J 13.4 B,J 17.7 B,J 11.9 B,J 8.9 B,J 11.0 B,J2ug/L 0.20ug/L ND ND ND ND ND ND

---- 0.0050ug/L ND 0.010 B ND ND ND 0.0019 B---- 0.0050ug/L ND ND ND ND ND ND

---- 0.20 mg/L 0.28 0.16 B 0.35 ND ND 0.080 B250mg/L* 1.0 mg/L 14.6 J 8.7 12.5 3 3.8 5.9 J2.0mg/L* 0.050 mg/L 0.11 0.11 0.17 0.11 0.2 0.110mg/L 0.050 mg/L 0.18 ND ND ND ND ND

250mg/L* 1.0 mg/L 36.3 41.2 29.5 13.2 25.8 145---- 5.0 mg/L 32.4 3.0 B 45.8 26.2 61 57.1

pH 4.8 4.4 5.63 5.12 5.52 5.88Specific Conductivity 104.3 140 221.6 96.3 179 559Temperature 18.91 19.1 21.92 21.75 19.81 25.89ORP 155 140 ---- 113 --- ---Dissolved Oxygen 1.15 1.5 1.13 0.56 0.66 2.71

36 0.68 136 467 181 50.7

RL = Reporting limit.

B= Estimated result. Result is less than RL.

J= Method blank contamination. The associated method blank contains the target analyte

Bold values indicate paramater exceeding MCL or secondary MCL.

NTUs

Field Parameters

Constituent:Aluminum:

Boron:Calcium:Copper:

Molybdenum:Sodium:Selenium:

Well ID:

Arsenic:

Metals

Iron:Potassium:Magnesium:Manganese:

Silicon:Vanadium:Zinc:Mercury:

*= Secondary MCL

at a reportable level.

Fluoride:Nitrate as N:Sulfate:Total Alkalinity:

Groundwater Quality ParametersParameter Units

ppm

Bromide:Chloride:

Gallium:

Turbidity

Tungsten:Anions

---uS/cmCelcius

mV

FIGURES

Figure 8

P-2 HydrographBauxite, Arkansas

360.4

360.5

360.6

360.7

360.8

360.9

361

361.1

361.2

361.3

361.4

361.5

361.6

0 8

Days

28.5

28.7

28.9

29.1

29.3

29.5

29.7

29.9

30.1

30.3

30.5

Bar

omet

ric P

ress

ure

(inch

es H

g)

Ele

vatio

n(f

t.m

sl.)

7/15

/07

7/16

/07

7/17

/07

7/18

/07

7/19

/07

7/20

/07

7/21

/07

7/22

/07

Barometric Pressure

Figure 9

P-5 HydrographBauxite, Arkansas

335

335.1

335.2

335.3

335.4

335.5

335.6

335.7

335.8

335.9

336

0 8 28.5

28.7

28.9

29.1

29.3

29.5

29.7

29.9

30.1

30.3

30.5

Ele

vatio

n (f

t. m

sl.)

Bar

omet

ric P

ress

ure

(inch

es H

g)

7/15

/07

7/16

/07

7/17

/07

7/18

/07

7/19

/07

7/20

/07

7/21

/07

7/22

/07

Barometric Pressure

Figure 10

P-8 HydrographBauxite, Arkansas

321.7

321.8

321.9

322

322.1

322.2

322.3

322.4

322.5

322.6

322.7

0 8 28.5

28.7

28.9

29.1

29.3

29.5

29.7

29.9

30.1

30.3

30.5

Bar

omet

ric P

ress

ure

(inch

es H

g)

Ele

vatio

n (f

t. m

sl.)

7/15

/07

7/16

/07

7/17

/07

7/18

/07

7/19

/07

7/20

/07

7/21

/07

7/22

/07

Barometric Pressure

Figure 11

Swamp Poodle HydrographBauxite, Arkansas

318.5

318.6

318.7

318.8

318.9

319

319.1

319.2

319.3

319.4

319.5

0 8 28.5

28.7

28.9

29.1

29.3

29.5

29.7

29.9

30.1

30.3

30.5

Bar

omet

ric P

ress

ure

(inch

es H

g)

Ele

vatio

n(f

t.m

sl.)

7/15

/07

7/16

/07

7/17

/07

7/18

/07

7/19

/07

7/20

/07

7/21

/07

7/22

/07

Barometric Pressure

APPENDIX A