3.5 Hydrogeology 3.5.1 Hydrostratigraphy 3.5.2 Aquifers

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and clays. The shallow surficial sand/silt unit underlying much of the tailings pile and Brine Pond has the most potential to allow lateral brine migration. Glaciolacustrine silts and clays, typically ranging from 5 m to 10 m thick, form the majority of the surficial soils at the mine site.

3.5 Hydrogeology

The discussion of the hydrogeology at the Allan Division mine site has been extracted from PCS Potash, 2005.

3.5.1 Hydrostratigraphy

The hydrostratigraphy of the study area (in ascending order), consists of the Lea Park shale aquitard, Judith River Aquifer, Bearpaw shale aquitard, Empress Aquifer, Sutherland till aquitards, Sutherland intertill aquifers, Forestry Farm aquifer, Floral till aquitards, Battleford till aquitard, and surficial stratified aquifers/aquitards. A geologic/hydrogeologic profile showing the hydrostratigraphy in the vicinity of the Allan Division mine, is illustrated in Figure 14.

3.5.2 Aquifers

The principal aquifers identified at Allan Division (in ascending order – see Figure 15), are the:

• Judith River Aquifer (Judith River Formation); • Sutherland Intertill Aquifers (within the Sutherland Group); • Floral Aquifers (Sutherland/Saskatoon Group contact - Upper Floral Aquifer;

Lower/Upper Floral till contact – Floral Intertill Aquifer); and, • Surficial Sand/Silt Aquifer.

THE REGIONAL HYDROSTRATIGRAPHYFOR THE AREA SURROUNDING THE

ALLAN DIVISION SITE

.

FIGURE: 15

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3.5.2.1 Judith River Aquifer

The Judith River Formation is found almost continuously throughout the regional area of the Allan Division site, except where it has been affected by collapse features and preglacial and glacial erosion. Below the Allan mine site, the Judith River Aquifer has been interpreted to be connected with the overlying Forestry Farm Aquifer (MDH 2004). The hydraulic conductivity of the Judith River aquifer ranges between approximately 1x10-5 m/s and 6x10-6 m/s (Maathius and van der Kamp 1994).

3.5.2.2 Empress Aquifers

The Empress Group gravel consists of thick, discontinuous erosional remnants, separating the Bearpaw shale from the Sutherland Group tills, or in some cases, the Lower Floral Aquifer. Where present, the average thickness of the Empress Group deposits range between 20 m and 40 m at various locations in the region. Therefore, the Empress Group sands and gravel form localized aquifers over the regional area. The Empress Group sediments do not appear to present significant pathways for brine migration at the Allan mine site because of their limited extent in the area.

3.5.2.3 Sutherland Intertill Aquifers

The Sutherland Intertill Aquifers are usually separated from the Lower Floral Aquifer by 10 m to 50 m of Sutherland Group till (MDH 2004). The Sutherland Intertill Aquifers are localized and discontinuous in nature, resulting in isolated Lower Floral aquifers within the regional area. Hydraulic properties and the lateral extent of the formation are not well known due to the absence of wells completed in these sands (MDH 2004).

3.5.2.4 Lower Floral Aquifer

The Lower Floral Aquifer (referred to as the “Forestry Farm Aquifer” in MDH 2004), which consists of sands, gravels, and occasional thin interfingers of till, is the major aquifer in the study region. This interbedded sand and gravel unit occurs at the base of the lower unit of the Floral Formation. The aquifer forms a thick valley fill sequence within a bedrock valley beneath the mine site’s North Brine Pond, forming a southeast to northwest trending channel (see Figure 15). This aquifer is not clearly defined and is discontinuous in the study area. In the Lower Floral Aquifer, groundwater flows predominantly northward from the Allan Division tailings management area, trending west towards Patience Lake and south and east to the south of the mine site in the direction of the Zelma Reservoir.

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The Lower Floral Aquifer appears to be hydraulically connected to the Judith River Formation in the bedrock valley. The Judith River's relatively low hydraulic conductivity and poor water quality, however, preclude its use as a domestic water supply, thus minimizing the importance of this connection. This channel aquifer is approximately 20 m to 40 m deep beneath the Allan Division tailings management area (MDH 2004), and is considered an important aquifer with respect to brine migration. The hydraulic conductivity of the Lower Floral Aquifer is in the range 6x10-3 m/s to 2x10-7 m/s (Domenico and Schwartz 1998). Maathuis et al. 1994, suggests that channel aquifers are likely a reflection of surficial features at depth. This channel aquifer is roughly 30 m deep beneath the Allan Division tailings management area and is considered to be a concern with respect to potential brine impacts as it is a regional aquifer.

3.5.2.5 Floral Intertill Aquifer

The Floral Intertill Aquifer is 0 m to 9 m thick below the Allan Division tailings management area and may be hydrodynamically connected to the Lower Floral Aquifer north of Patience Lake (MDH 2004). This aquifer occurs as scattered deposits beneath the Allan Division tailings management area (hydraulically discontinuous).

3.5.2.6 Surficial Aquifers

The Surficial Stratified Deposits are important, but restricted, unconfined aquifers with respect to shallow brine migration in the vicinity of the mine site. According to the drilling results for the site, the majority of boreholes encountered silts and clays in the Surficial Stratified Deposits. Specifically, the thin surficial silt/sand unit underlying most of the Allan Division tailings management area has been identified a potential shallow brine migration pathway. The lateral extent of the Surficial Stratified Deposits is very complex, but the surficial stratified silts are interpreted as largely being continuous around the Allan site.

3.5.3 Aquitards

The main aquitards that control vertical brine migration in the area of the Allan Division tailings management area are the clays of the Surficial Stratified Deposits, and the Battleford and Floral tills that overlay and/or confine the Floral aquifers. These aquitards are approximately 7 m to 36 m thick, in the vicinity of the Allan mine site (MDH 2004).

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Typical hydraulic conductivity values for Saskatchewan tills are summarized in a report written for the Saskatchewan Potash Producers Association (Maathuis and van der Kamp 1994). Generally, thick, unfractured tills in the Saskatoon and Sutherland Groups have hydraulic conductivities between 1x10-10 m/s to 1x10-11 m/s. The shallower, fractured and unoxidized tills possess hydraulic conductivities that range between 1x10-8 m/s to1x10-9 m/s. Hydraulic conductivities of 1x10-7 m/s to 1x10-8 m/s are typical values for shallow, oxidized and fractured tills within the Floral Formation.

3.5.4 Regional Groundwater Flow

The Bradwell Reservoir, Cheviot Lake, Crawford Lake, Patience Lake Porter, and Burke Lake are the main surface water bodies situated in the regional area (see Figure 12). Topographically elevated areas are present southwest of the Allan Division tailings management area, plus the Strawberry Hills, and topographically elevated areas east of Patience Lake, to the north of the Allan mine site. These topographic highs represent groundwater flow divides. These topographic highs focus surface water drainage toward the topographically low region, characterized by the prominent surface water bodies mentioned above.

The water table is interpreted to be close to surface in the low-lying areas. Surface water flows west-northwestward from the Allan TMA towards Patience Lake and then north toward Porter Lake. Surface water also flows to the southeast of the Allan TMA toward the Zelma Reservoir.

Piezometric head contours indicate that the bedrock valley acts as a regional drain and that groundwater flows is directed towards the TMA from the north and south (MDH 2004). An east-west groundwater divide appears to be located within the valley in the vicinity of the mine site. As the hydraulic gradients are very flat in the bedrock valley, it is difficult to determine the direction of groundwater flow along the axis of the valley. However, the small horizontal gradients indicate that groundwater flows downward into the bedrock valley near the Brine Pond and moves along the valley towards the northwest. This regional flow pattern agrees with a previous study by Beckie (1968) and potentiometric surface maps of the area produced by Saskatchewan Environment and Resource Management (now known as Saskatchewan Environment).

3.5.5 Groundwater Flow Direction

Pre-mining groundwater flow was generally directed from the southwest to the northwest across the Allan Division tailings management area. Regionally, groundwater flows towards surface water channels located northwest of the tailings management area towards Cheviot Lake and subsequently Patience Lake (MDH 2004). In the immediate

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area to the north of the tailings management area, pre-mining flows were directed to the east. Pre-mining groundwater heads range from more than 530 m asl to a little less than 517 m asl in the vicinity of the mine site, with a gradual downward gradient for groundwater flow in the vicinity of the Allan Division tailings management area (MDH 2004).

The Lower Floral Aquifer is considered the most important aquifer in the Allan Division area. This aquifer is discontinuous in the study area, forming a southeast to northwest trending channel. Groundwater flows predominantly northward from the Allan tailings management area, and trends west towards Patience Lake. South of the mine site groundwater flow is directed to the south and east towards the Zelma Reservoir (MDH 2004).

3.6 Soils

The mine site area is characterized by soils of the dominantly Solonetzic series of the Hanley Association and the dominantly Chernozernic series of the Elstow Association. Smaller portions of the Chernozernic Wyandotte and Bradwell Associations are also present in the vicinity (Ballantyne 1968). These soils are described as dominantly dark brown, with the Hanley, Elstow, and Bradwell Associations being of a medium to moderately fine texture (Acton and Ellis 1978). The Wyandotte Association has a moderately fine, to fine texture. All are moderately calcareous and of glaciolacustrine origin.

3.7 Vegetation

The mine site is located on the Elstow Plain Landscape Area of the Moist Mixed Grassland Ecoregion in the Prairie Ecozone (Acton et al. 1998). The majority of this semi-arid ecoregion consists of Class 4 lands, where 10% to 30% of the landscape supports native vegetation and/or introduced perennial forage crops (Figure 16), with the remaining 70% to 90% used to produce annual crops and/or for other purposes (Hart and Hunt 1981). Cereals are the major crop in the area, with a small amount of oilseeds (Acton et al. 1998). Generally, the remnant, native habitat types in the Project area are mostly limited to wetlands and non-arable pasture lands (Figure 17), associated with stony and hummocky moraines.

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HABITAT MAP

FIGURE: 16

LegendCurrent Mine Footprint

AgDFG

Agricultural (Cropland, Hayland or Pastureland)Disturbance Area (Gravel Pit, other Infrastructure)Farm YardGrassland

MT

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FILE No.SCALE AS SHOWN

FIGURE: 17REV. 0

PROJECT

TITLE

PROJECT DESIGN

GISCHECK

LAND CATEGORIESIN THE STUDY AREA

REVIEWSaskatoon, Saskatchewan

JRC 17/03/06

06-1362-231.2000

Allan Mine Site

Area of Interest

G:\2

006\1362\0

6-1362-2

31 PCS

Allan Fin

e Tails M

angement\GIS\

06-1

362-

231-

PCS Allan Fine

Tails Ma

nagement Land C

over 1117.mxd

Allan DivisionPotash Corporation of Saskatchewan Inc.

1 10

KILOMETRESSCALE 1:50,000

Cultivated LandHay Crop (Forage)Native Dominant GrasslandTall ShrubPasture (Seeded Grassland)Hardwood (Open Canopy)Hardwood (Closed Canopy)Jackpine (Open Canopy)Jackpine (Closed Canopy)Spruce (Closed Canopy)Spruce (Open Canopy)Mixed WoodTreed RockRecent BurnRevegetating BurnCutoverWaterbodyMarshHerbaceous FenMud/Sand/SalineShrub Fen (Treed Swamp)Treed BogOpen BogFarmsteads and Communities

Legend

Reference:Saskatchewan Environment and Resource Management

GAM 10/04/06

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Trembling aspen (Populus tremuloides) is the dominant tree species in the Project area and is frequently found in uncultivated depressions or surrounding wetland basins. Shrubland communities, found in depressions, on the margins of trembling aspen bluffs and surrounding wetlands, primarily consist of western snowberry (Symphoricarpos occidentalis), rose (Rosa spp.), chokecherry (Prunus virginiana) silverberry (Elaeagnus commutata) and saskatoon (Amalanchier alnifolia). The native, mixed grassland communities are typically dominated by such species as: spear grasses (Hesperostipa spp.), with June grass (Koleria macrantha), wheat-grasses (Elymus spp.) blue grama grass (Bouteloua gracilis), blue grasses (Poa spp.), several dryland sedges (Carex spp), pasture sage (Artemisia frigida), hairy golden aster (Heterotheca villosa), Canada goldenrod (Solidago Canadensis), common yarrow (Achillea millefolium var. millefolium) and gaillardia (Gaillardia aristata). Native vegetation in the area of the proposed fine tailings management areas appears to be extremely limited and restricted to primarily small wetland basins and drainages.

Freshwater wetlands in the Project area are dominated by cattail (Typha latifolia), bulrushes (Scirpus spp.), sedges (Carex spp.), willows (Salix spp.), water smartweed (Polygonum amphibium), marsh reed-grass (Calamogrostis canadensis) and northern reed-grass (Calamogrostis stricta) (Hart and Hunt 1981). Reed canary grass (Phalaris arundinacea) is also common in these areas. Wetlands and poorly drained low-lying areas with higher salinity, including the brine ponds associated with the existing mine site, likely support more salt-tolerant species including red samphire (Salicornia rubra), saline goosefoot (Chenopodium glaucum), red goosefoot (Chenopodium rubrum), kochia (Kochia scoparia), western seablite (Suaeda depressa), seaside arrowgrass (Triglochin maritima), perennial sow-thistle (Sonchus arvensis) and gumweed (Grindelia squarrosa). Grasses commonly encountered in these moist saline areas include foxtail barley (Hordeum jubatum), Nuttall’s salt meadow grass (Puccinellia nuttalliana) salt grass (Distichlis stricta), and occasionally, alkali cord grass (Spartina gracilis). Needle spike rush (Eleocharis acicularis) is also found in these areas, often forming a low dense mat. Many of these species are likely present on the mine site.

Introduced plant species, primarily crested wheatgrass (Agropyron cristatum spp. pectinatus) and smooth brome (Bromus inermis ssp. inermis), are also likely present in the Project area, including the site of the proposed for the fine tailings management area. These species are aggressive colonizers that were introduced into many areas of Saskatchewan for forage crops, wildlife habitat creation and for vegetating road ditches and low maintenance, open areas. Additional introduced weed species would typically include: yellow sweet clover (Melilotus officinalis), baby’s breath (Gypsophila paniculata) and flixweed (Descurainia sophia). Alfalfa (Medicago sativa) is likely the dominant species on the haylands in the Project area.

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Based on a search of the Saskatchewan Conservation Data Centre (SCDC) database (SE 2006), there are no federally or provincially listed plant species located within the Project area.

3.8 Fisheries Habitat

Based on a review of NTS mapsheet 72 O/16 (1:50,000 scale) there are no permanent watercourses, waterbodies or other areas potentially supporting fish habitat that would come in contact with the proposed project or that would be impacted by the proposed project. No works will be occurring below the high water mark of a fish bearing water, therefore, a review by Fisheries and Oceans Canada will not likely be required. The project will not likely require an Aquatic Habitat Protection Permit issued by SE if no works will take place within the minimum set-back distance of a fish bearing watercourse or waterbody.

3.9 Wildlife

While the majority of the landscape within the Project area has been previously disturbed and modified by the mining operation and agricultural, suitable habitat for use by a wide range of wildlife species remains. Based on previously completed reports and knowledge of the site, habitat types within the Project area likely support a variety of wildlife species, including ungulates, furbearers and rodents. White-tailed deer (Odocoileus virginianus) are commonly found in the Project area where perennial forage crops occur in proximity to woody patches (i.e., trembling aspen clones) and wetland basins,. Recent and increased sightings of mule deer (Odocoileus hemionus) indicate that this species is also becoming re-established in the area. Other common wildlife species that may find suitable habitat types in the Project area include coyote (Canis latrans), red fox (Vulpes vulpes), American badger (Taxidea taxus), striped skunk (Mephitis mephitis), white-tailed jackrabbit (Lepus townsendii) and Richardson ground squirrel (Spermophilus richardsonii).

The Project area contains a number of seasonal and saline wetlands used by waterfowl and shorebird populations. Wetlands and their associated habitats in the Project area may provide breeding and staging areas for these species, particularly ephemeral and seasonal basins with exposed mudflats and low water levels. Common species found in these habitats would include northern pintail (Anas acuta), blue-winged teal (Anas discors), northern shoveler (Anas clypeata), Wilson’s phalarope (Phalaropus tricolor), killdeer (Charadrius vociferous), and American avocet (Recurvirostra Americana). Larger, more permanent freshwater wetlands would typically support species such as mallard (Anas platyrhynchos), gadwall (Anas strepera), lesser yellowlegs (Tringa flavipes), American

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coot (Fulica Americana), Franklin’s gull (Larus pipixcan), red-winged blackbird (Agelaius phoeniceus) and yellow-headed blackbird (Xanthocephalus xanthocephalus).

Upland birds in the Project area surrounding the mine site would typically include: sharp-tailed grouse (Tympanuchus phasianellus), grey or Hungarian partridge (Perdix perdix), eastern kingbird (Tyrannus tyrannus), western meadowlark (Sturnella neglecta), song sparrow (Melospiza melodia), and Vesper sparrow (Pooecetes gramineus). Raptors commonly found in the area would include great horned owl (Bubo virginianus), Swainson’s hawk (Buteo swainsoni), red-tailed hawk (Buteo jamaicensis), and northern harrier (Circus cyaneus). These species have typically adapted to the type of disturbance associated with the Project area (e.g., agricultural and mining activities) and continue to inhabit the modified habitats on a seasonal or year-round basis.

Within the Project area, there are no lands legislated under the Wildlife Habitat Protection Act (WHPA 1997) nor are there areas designated as classified wildlife habitat. WHPA lands are Crown lands legislated for protection and management for agriculture and wildlife. Classified wildlife habitat is defined as the best habitat within the map area for the species listed, that may be of seasonal or year-round importance and is essential to the maintenance of current populations (Hart and Hunt 1981). There are no Saskatchewan Fish and Wildlife Development Fund or Saskatchewan Wildlife Federation Habitat Trust lands located in the Project area (SE 2006). A Ducks Unlimited Canada (DUC) project is located within the Project area at SW 24-34-1 W3M (J. Trevor, DUC – Saskatoon, personal communications, 2006), approximately 3 km east of the mine site.

3.9.1.1 Sensitive Wildlife Species

Eight wildlife species listed federally by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC 2006) have breeding ranges that overlap with the proposed Project area and include:

• endangered - piping plover and burrowing owl (Athene cunicularia); • threatened - loggerhead shrike (Lanius ludovicianus) and Sprague’s pipit (Anthus

spragueii); and, • species of concern - long-billed curlew (Numenius americanus), short-eared owl

(Asio flammeus), northern leopard frog (Rana pipiens), and monarch butterfly (Danaus plexippus).

Based on the habitat types present within the Project area, it is anticipated that only the piping plover, burrowing owl, loggerhead shrike, Sprague’s pipit, short-eared owl and monarch butterfly could potentially be encountered.

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3.9.1.2 Endangered

The piping plover prefers to nest on sand or gravel beaches of saline or freshwater lakes, rivers, and wetlands (Godfrey 1986). The ponds at the Allan mine are known as one of the best sites to observe this species (Hartley and Hay, Saskatchewan Natural History Society 2002). Because of this occurrence at the Allan mine, it is likely the piping plovers utilizing these ponds have become habituated to the activities associated with mine operations.

The burrowing owl prefers pastureland that has been grazed, but they can be found nesting in ditches and along road allowances (Godfrey 1986). With the range of the burrowing owl receding to more southerly areas (Smith 1996), this species is unlikely to be encountered in the Project area. There are no known sightings for this species in the Project area (SE 2006) and the habitat surrounding the mine site is considered to be marginal for this species.

3.9.1.3 Threatened

Loggerhead shrikes typically inhabit open areas having shrub and hedgerow vegetation utilized for hunting and nesting habitat (Godfrey 1986; Telfer et al. 1989). Potential habitat is limited to hedgerows and/or tall shrub habitat present in the general region. No historical sightings were listed for this species in the area of the mine site by the Saskatchewan Conservation Data Centre (SCDC) (SE 2006).

Sprague’s pipits are typically found in short-grass prairies that have not been ploughed or burned (Godfrey 1986). Habitat for this species may be present in the general area where remnant prairie exists; however, this species is unlikely to be encountered in the mine site. No historical sightings were listed for this species in the area of the mine site by the SCDC (SE 2006).

3.9.1.4 Special Concern

Short-eared owls typically prefer open grassland and hayland areas, particularly adjacent to wetlands and wet meadows (Godfrey 1986). Suitable habitat may be present in hayland or remnant grassland areas in the Project area; however, this species is unlikely to be encountered in the mine site area. No historical sightings were listed for this species in the Project area (SE 2006).

The monarch butterfly feeds on plants with bitter or poisonous sap and eggs are generally laid in mid to late spring on milkweed plants (Layberry et al. 1998). Potential habitat may exist in the Project area if milkweed plants are present.

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3.10 Heritage Resources

Heritage properties include all of Saskatchewan’s historic and precontact archaeological sites, architecturally significant structures, and paleontological resources. As per Section 66 of The Heritage Property Act, all heritage resources on privately owned land, Provincial Crown Land and those PFRA lands that are leased from Saskatchewan Agriculture and Food (SAF) are considered to be property of the Crown. Per Section 63 of The Heritage Property Act, the Heritage Resources Branch can require that a Heritage Resource Impact Assessment (HRIA) be completed before a project can proceed.

Following the Heritage Resources Branch screening criteria, the need for HRIA is based on three main factors: 1) nature of the development (disturbance to soils and sediments where cultural materials may be located); 2) significance of previously documented heritage resources; and, 3) the potential for additional undocumented heritage resources to be identified within the local topography.

There are no previously recorded archaeological or historic sites in potential conflict with the proposed project. The project area consists largely of level, cultivated and otherwise modified terrain in with no permanent water courses or well formed valleys within 1 km. The likelihood of encountering significant, undisturbed archaeological deposits in the proposed project area is low. As a result, it is recommended that formal HRIA not be required in these locations.

Although this area is considered to have low heritage potential, there always remains the possibility that significant, intact archaeological components may exist. If cultural materials are identified at any time during project construction activities, they must be reported to the Heritage Resources Branch and further assessment and/or mitigation may be required.

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4.0 POTENTIAL IMPACTS AND MITIGATIVE MEASURES

4.1 Surface Water

There are no major water bodies, rivers or streams within the immediate vicinity of the Allan Division mine site. The most prominent water body is the Bradwell Reservoir, located about 4.5 km southwest of the site (Figure 12). The tailings management area occupies a closed topographical depression within the lowland and is the destination for run-off from the mine site. Where mine site run-off was destined for other depressions, a drainage system has been installed to direct this run-off to the tailings management area.

No impacts to surface water bodies are anticipated as a result of the construction of the fine tailings management area.

4.2 Groundwater

Potential for groundwater impacts for the proposed long term salt pile development has been assessed in the Allan TMA Groundwater Flow and Transport Model (MDH 2004). The location of the preferred location of the fine tailings management area (Option 2B) was not included in simulations considered, however, an alternate brine pond located south of the salt pile was evaluated which provides a reasonable approximation of the alternate location (Option 2C) of the fine tailings management area. MDH (2004) concluded that predictive simulations generally indicate a continued spreading of the surficial brine plume with low and generally reducing rates of downward movement of brine over most of the tailings management area. Shallow brine migration was strongly influenced by the surficial geology but was constrained by engineered drains.

The location of the Forestry Farm Aquifer, Floral Intertill Aquifer and the continuity of aquitards above the aquifers require better definition to allow an assessment of the natural containment and potential for brine impacts to the aquifer for the preferred and alternate fine tailings management areas. The stratigraphic investigation program to be undertaken in 2006 will provide additional information of at both potential locations of the fine tailing management areas.

Detailed geotechnical investigations in the footprint of the proposed fine tailings management areas to characterize the surficial geology are key to evaluating the natural containment offered at the two locations and the assessment of the feasibility of potential engineered controls for brine containment.

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4.2.1 Groundwater Contamination and Monitoring Procedures

All environmental monitoring is conducted to comply with the requirements of the Environmental Management and Protection Act and Regulations and the Clean Air Act and Regulations.

The required monitoring program is stipulated in the Approval to Operate Pollutant Control Facilities, issued by SE, pursuant to Section 8(l) of the Mineral Industry Environmental Protection Regulations.

A total of twenty-two monitoring wells located around the periphery of the TMA are monitored for water level and chemistry. Eleven of the wells are shallow wells, and are labelled as the "X-Series" wells (also includes 92-06). Six are completed in the Lower Floral Sand and Gravel Aquifer (Forestry Farm Aquifer). The remaining five wells are completed in the Floral Intertill Aquifer.

Most of the wells were installed prior to the start-up of the mine. They were located within the most probable routes of potential brine release, based upon a stratigraphic evaluation of the mine site. The X-Series wells, 9X1, 10X, and 11X were installed in 1978, when the North, or lower brine pond was created (Meneley 1979).

All water sampling for environmental monitoring is performed by Allan Division personnel. Detailed chemical analysis is performed by the PCS Pilot Plant Research laboratory in Saskatoon. Water quality data is entered into a computer database and spreadsheet, and is used to determine if there has been brine impacts of surface water or groundwater. Groundwater level elevation information is also entered into a database.

Geophysical surveying techniques such as EM39 and GEM-2 (formerly EM34), have been used recently to assess areas of potential brine seepage. These techniques can provide a relative measurement of apparent conductivity around the tailings management area.

Modifications to the existing groundwater monitoring system will be developed as part of the detailed design of the fine tailings management area.

4.3 Brine Management

Brine pond levels are maintained as low as is practicable, in order to reduce the hydraulic head acting on the dykes and the base of the ponds. Operation of the brine ponds at low levels also ensures compliance with the normal and minimum freeboard standards specified by CANMET.

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The dykes have been designed to withstand a Major Storm Event of 300 mm in 24 hours. Brine levels are maintained such that the minimum freeboard requirements would not be exceeded by this storm. The brine containment after a Major Storm Event was studied and reported on in 1999 when the North Pond was returned to service. No changes have been made in the tailings management area since 1999 to affect brine storage capacity and the operating levels.

Brine pond levels are recorded daily, and reported as monthly averages. These levels are also monitored continuously in the mill control room.

Excess brine is injected to the Deadwood Formation. Annulus testing and down hole pressure falloff testing is performed annually on the injection well. Injection wellhead pressures are checked and recorded daily. Injection pump pressures and flow are monitored continuously in the mill control room. Injection brine is sampled monthly and analyzed for potassium, sodium and chloride (K, Na, and Cl). This data is used in calculating brine injection volumes and salt disposal tonnages.

A second brine injection well is planned for 2006 to increase the capacity of the brine injection system. The second well will allow for increased production rates and provide reserve capacity for years with higher than average precipitation. Otherwise, there are no changes proposed for the existing brine management system.

4.4 Vegetation

Based on a search of the SCDC database (SE 2006), there are no federally or provincially listed plant species located within the Project area.

There is no formal monitoring program in place at this time to monitor the effect of the mine on local vegetation. An informal visual assessment of the state of vegetative growth around the mine site is conducted by Allan Division personnel when they purge and sample the piezometers located around the immediate vicinity of the mine site.

To date, no adverse effects on vegetation have been noted visually, other than in the immediate vicinity of the TMA, where some impacts are expected. This system does not scientifically document subtle changes in vegetation patterns and thus, by its very nature, is a gross measure of the health of surrounding vegetation.

Vegetation research conducted by R.E. Redmann and M.K.A. Ryan, Department of Crop Science and Plant Ecology, University of Saskatchewan, 1983 to 1987, Contract M-6036, arrived at the following conclusions:

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1. Cereal crops are not damaged by “normal” potash dust emissions. 2. Most native vegetation is not affected by potash dust. 3. Some ornamental trees can be damaged by potash dust but the most sensitive tree is

the common native Aspen or Poplar. 4. Damage to Aspen is evident by the death of buds and leaves on the actively growing

twigs. 5. Aspen trees are most sensitive to damage at the time the buds are opening, which is

usually early to mid May. There is little damage produced by exposure to potash over the period when there is no green growth present. Leaves become more tolerant to potash dust as they become older.

6. K2SO4 is slightly less toxic than NaCl or KCl. 7. Higher levels of salt exposures produce higher levels of vegetation damage.

On the basis of these conclusions, a visual assessment for vegetation damage is deemed sufficient. Based on the insignificant impact of the operation on vegetation to date, no significant long term impact is anticipated from the construction and operation of the proposed fine tailings management area.

4.5 Soils

Soil surveys, conducted of the area immediately surrounding the Allan mine site prior to commencement of mining operations, indicated that salinity was prevalent (seven soil surveys have been completed to date). Hanley soils with saline parent material and high soluble sodium levels, were common. The Elstow soils were often found to have gypsum present in the subsoil. More detailed baseline data is available in Ballantyne (1968), and Acton and Ellis (1978). Soil sampling and analysis has been conducted at the Allan Division mine site since 1965 as part of a study conducted to evaluate the effect of air-borne salts on the soils in the vicinity of potash mines. A. K. Ballantyne of the Saskatchewan Institute of Pedology conducted a soil survey within approximately a six mile radius of the mine site (Ballantyne 1968; also see Figures 4-19 and 4-20, Potash Corporation of Saskatchewan Inc. 1997). Representative soil sampling sites marked 1-38 on Figure 3 were established within the surveyed area, and soil samples were obtained and analyzed from 1965 through 1970. A comprehensive review of the data collected was conducted in 1975 by C.G.E.M. van Beck (1975), of the Saskatchewan Institute of Pedology.

In 1985, a new voluntary sampling program was established similar to the one recommended by van Beck (1975). Seven sampling sites within a 1 km radius of the mine site were established and have been sampled on a four year basis. The sampling frequency has been extended to five years. The soil data collected to date provides a

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valuable record of the historic soil conditions as well as documenting any changes that may have occurred since production began.

Although some changes in soil chemistry have been noted over time, these have not been significant. Natural soil salinity is common throughout the Allan Mine site area, thus making it difficult to detect any changes. Increased utilization of forage crops and the reduction in summer fallow have been recommended to decrease salinization to remove any added potassium. These practices are being encouraged within the mine site area.

Based on the insignificant impacts experienced after more than 30 years of operation and the insignificant additional dust generated as a result of this expansion, it is recommended that soil monitoring continue at a frequency of once every five years. The soil sample program was conducted in the summer of 2004 (next scheduled to be completed in 2009).

4.6 Wildlife

No impacts to wildlife are anticipated as a result of the development of the proposed fine tailings management area.

4.7 Heritage Resources

The likelihood of encountering significant, undisturbed archaeological deposits in the proposed project area is low. As a result, it is recommended that formal HRIA not be required in these locations.

4.8 Air Quality

No impacts to air quality are anticipated as a result of the development of the proposed fine tailings management area.

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5.0 DECOMISSIONING AND RECLAMATION

Allan Division has an approved decommissioning and reclamation (D&R) plan registered with SE, dated March 1997. The report has been conditionally approved until July 1, 2006 on the basis that several updates and studies would be conducted before the 2006 submission. The proposed fine tailings management area will be accounted for in the 2011 revised D&R plan and submitted to SE at that time. The agreed cut off date for site data for the upcoming 2006 decommissioning plan is December 31, 2005.

The fine tailings management facility will be constructed in a manner that will maintain brine within the facility to promote vegetation on dyke slopes as part of operations. Continued studies will be undertaken to refine construction methods to assist in mitigating brine from seeping through dykes to maintain a vegetated slope with an objective of progressively decommissioning the slopes of the fine tailings management area.

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6.0 PUBLIC CONSULTATION

The Allan Division has been in production since 1968 producing potash on the same site. During this time, the site has had a positive relationship with the community and endeavours to support the local community whenever possible. Concerns have been very few over the years and concerns are promptly addressed. The one concern in the last five years from the municipality over drainage along the Bradwell Road was addressed promptly. In 2004, the well water for local farmers was sampled and the results of the water testing was sent to them. They were asked during the sampling if there were any concerns and none were raised.

Public meeting for this project will be based on a needs assessment in consultation with SE.

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7.0 SOCIO-ECONOMICS

This project will be designed and constructed with Saskatchewan labour. The majority of the services, labour, and supplies will be sourced from local communities.

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8.0 CLOSURE

We trust that this report is sufficient for your present needs. Please contact Golder at your convenience if you have any questions or comments.

GOLDER ASSOCIATES LTD.

Prepared by:

Cameron Jackson, M. Sc. Greg Misfeldt, P.Eng. Wildlife Ecologist Associate, Senior Geotechnical Engineer

Reviewed by:

Phil Bruch, M. Sc., P.Eng. Associate, Senior Geotechnical Engineer

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9.0 LITERATURE CITED

Acton, D.F., G.A. Padbury, and C.T. Stushnoff. 1998. The Ecoregions of Saskatchewan. Canadian Plains Research Centre. University of Regina.

Christiansen, 1968. Pleistocene Stratigraphy of the Saskatoon Area, Saskatchewan. Canadian Journal of Earth Sciences, 5: 1167-1173.

Christiansen, E.A., S.H. Whitaker, W.A. Meneley, and C.G. Elias, 1970. Physical Environment of Saskatoon Canada. NRC Publication Number 11378.

Christiansen, 1979. Geology of the Saskatoon Region, Saskatchewan. E.A. Christiansen Consulting Ltd. Report No. 00016-002.

Christiansen, E.A., 1992. Pleistocene stratigraphy of the Saskatoon area, Saskatchewan, Canada; an update. Canadian Journal of Earth Sciences, National Research Council of Canada. Ottawa, ON, Canada. 1992

Committee on the Status of Endangered Wildlife in Canada (COSEWIC). 2006. Species at Risk – January 2006.

Domenico, P.A. and W. Schwartz, 1998. Physical and Chemical Hydrogeology. John Wiley and Sons, Inc., New York.

Godfrey, W.E. 1986. The Birds of Canada. National Museum of Canada. 595 pp.

Clifton Associates Ltd., 1996. Phase I Regional Geologic and Hydrogeologic Compilation. Allan, Saskatchewan. Report prepared for Potash Corporation of Saskatchewan, January 1996.

Golder Associates Ltd., 1997. Assessment of Potential for the Movement of Brine into and Through the Deeper Aquifers Under PCS Allan Division. Prepared for Potash Corporation of Saskatchewan, January 1997.

Golder Associates Ltd., 2004. Piezo-Cone Penetration Testing Program Agrium and PCS Cory Mines. Prepared for Saskatchewan Potash Producers Association, March 2004.

Golder Associates Ltd., 2004a. Geotechnical Characterization Deposited Fine tailings PCS Cory Mine. Prepared for Saskatchewan Potash Producers Association, November 2004.

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Golder Associates Ltd., 2004b. Literature Review and Geotechnical Characterization Deposited Slimes PCS Allan Mine. Prepared for Potash Corporation of Saskatchewan Inc. November 2004.

Golder Associates Ltd., 2005a. Slimes Bench Scale Testing, PCS Pilot Plant, Saskatchewan. Report to Potash Corporation of Saskatchewan Inc., July 2005.

Golder Associates Ltd., 2005b. Short and Long Term Operational Planning, Allan Division Tailings Facility, Allan, Saskatchewan. Report to Potash Corporation of Saskatchewan Inc., Allan Division, December 2005.

Hart, R.T. and R.M. Hunt. 1981. Terrestrial Wildlife Habitat Inventory of the Rosetown (72O) Map Area, Technical Report 81-3, Wildlife Branch, Dept. of Parks and Renewable Resources, Saskatoon, Sask. 172 pp plus maps.

Layberry, R.A., P.W. Hall and J.D. LaFontaine. 1998. The butterflies of Canada. NRC Research Press, Canada Institute for Scientific and Technical Information. University of Toronto Press. 280 pp.

Maathuis, H. and G. van der Kamp, 1994. Subsurface brine migration at potash waste disposal sites in Saskatchewan. SRC Publication No. R-1220-10-E-94.

MD Haug & Associates, 1998. Buried Valley Investigation. Prepared for PCS Allan Division, February 1998.

MDH Engineered Solutions Corp., 2004. Allan Division tailings management area Groundwater and Transport Model. Report to Potash Corporation of Saskatchewan, May 2004.

MDH Engineered Solutions Corp., 2004a. tailings management area Management Study 2004 Summary – PCS Allan. Report to Potash Corporation of Saskatchewan Inc. Allan Division, April 2005.

MDH Engineered Solutions Corp., 2005. Slope Stability/Tailings Pile Optimization, 2005 Summary – Allan Division, Preliminary Report. Report to Potash Corporation of Saskatchewan, Allan Division, December 2005.

Padbury, G.A. and Acton, D.F., 1994. Ecoregions of Saskatchewan (map), Minister of Supply and Services Canada and Saskatchewan Property Management Corporation, 1994.

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Potash Corporation of Saskatchewan Inc., 2006. Decomissioning and Reclamation Plan, Allan Division.

Saskatchewan Environment, 2006. Sensitive species web site: http://gisweb1.serm.gov.sk.ca/wildlifelogin/form.asp.

Schreiner, B.T., 1992. Geology of the Glacial deposits of Southern Saskatchewan. In: Engineering Geology of Glacial Deposits, Saskatoon, Saskatchewan, One Day Seminar, Sponsored by Saskatoon Geotechnical Group, Saskatchewan Research Council and Department of Civil Engineering, University of Saskatchewan.

Smith, A.R. 1996. Atlas of Saskatchewan Birds. Special Publication No. 22. Environment Canada. Nature Saskatchewan.

Telfer, E.S. C. Adam, K. DeSmet and R. Wershler. 1989. Status and distribution of the Loggerhead Shrike in western Canada. Canadian Wildlife Service. Progress notes, No. 184.

Whitaker and Christiansen, 1972. The Empress Group of Southern Saskatchewan. Canadian Journal of Earth Sciences, Volume 9: 353-360.

APPENDIX I

SHORT AND LONG TERM OPERATIONAL PLANNING ALLAN DIVISION TAILINGS FACILITY

REPORT ON

Submitted to:

Potash Corporation of Saskatchewan, Inc., Allan Division

Allan, Saskatchewan S0K 0C0

DISTRIBUTION: 4 Copies - Potash Corporation of Saskatchewan, Inc., Allan Division 2 Copies - Golder Associates Ltd., Saskatoon, Saskatchewan December 2005 05-1362-143

SHORT AND LONG TERM OPERATIONAL PLANNING

ALLAN DIVISION TAILINGS FACILITY ALLAN, SASKATCHEWAN

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PCS ALLAN.DOC

TABLE OF CONTENTS

SECTION PAGE Table of Contents............................................................................................................. i 1.0 INTRODUCTION......................................................................................... 1 2.0 DESIGN CRITERIA..................................................................................... 2 3.0 LONG-TERM TAILINGS MANAGEMENT OPTIONS ................................ 3

3.1 Discussion of Options..............................................................................3 3.1.1 Option 1 .......................................................................................4 3.1.2 Option 2A.....................................................................................5 3.1.3 Option 2B.....................................................................................5 3.1.4 Option 2C.....................................................................................6 3.1.5 Option 2D.....................................................................................6 3.1.6 Option 3 .......................................................................................7

3.2 Evaluation of Options ..............................................................................8 3.2.1 Environmental Impact ..................................................................8 3.2.2 Operations ...................................................................................9 3.2.3 Economic .....................................................................................9 3.2.4 Decommissioning ......................................................................10

3.3 Preferred Option ....................................................................................10 4.0 SHORT TERM OPERATIONAL PLANNING............................................ 12 5.0 LONG TERM OPERATIONAL PLANNING .............................................. 14 6.0 CLOSURE................................................................................................. 15

LIST OF TABLES

Table 1 Evaluation of Options ............................................................................11

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PCS ALLAN.DOC

TABLE OF CONTENTS Continued

LIST OF FIGURES

Figure 1 General Arrangement Plan...................................... in order following text Figure 2 Existing Conditions Figure 3 Option 1 – Final Topography Figure 4 Option 1 - Cross Sections Figure 5 Option 2A – Final Topography Figure 6 Option 2A – Cross Sections Figure 7 Option 2B – Final Topography Figure 8 Option 2B – Cross Sections Figure 9 Option 2C – Final Topography Figure 10 Option 2C – Cross Sections Figure 11 Option 2D – Final Topography Figure 12 Option 2D – Cross Sections Figure 13 Option 3 – Final Topography Figure 14 Option 3 – Cross Sections Figure 15 Short Term Operation Phase 1 Figure 16 Short Term Operation Phase 2 Figure 17 Short Term Operation Phase 3 Figure 18 Short Term Operation Cross Sections Figure 19 Long Term Operation Stage 1 Figure 20 Long Term Operation Stage 2 Figure 21 Long Term Operation Stage 3 Figure 22 Long Term Operation Stage 4 Figure 23 Long Term Operation Stage 5 Figure 24 Long Term Operation Stage 6 Figure 25 Long Term Operation Stage 7 Figure 26 Long Term Operation Final Configuration

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1.0 INTRODUCTION

Potash Corporation of Saskatchewan, Inc. (PCS), Allan Division, retained Golder Associates Ltd. (Golder) to prepare short and long term plans for the operation of the Allan Division tailings facility including options for disposal of both salt tailings and slimes. The requirement for the short term options was to reduce potential impacts on the long term operation of the facility, while providing sufficient storage capacity until alternate options for long term operation of both the salt and slimes could be developed. The long term options were to provide sufficient capacity for both salt and slimes tailings for an operating period of 25 to 30 years.

PCS has deposited slimes in cells constructed on top of the salt pile for a number of years. In the summer of 2005, the height of the slimes cell containment was increased. The slimes are discharged at the south end of the slimes cells on top of the pile. Recently, the slimes have been observed flowing into “Rat Holes” in the salt pile and daylight at the toe of the pile near the south end. The overall stability of the salt pile may be impacted by continued placement of slimes in the existing cells , particularly if the salt pile is to be raised in the future as the slimes impoundment will have a significant impact on the hydraulic conditions within the tailings pile, which in turn will have an effect on tailings pile slope stability. For these reasons, PCS wishes to develop an alternate plan for management of the slimes which will move the slimes disposal off the top of the salt pile.

The requirement for the plan for management of the salt tailings was to provide containment for the salt tailings produced over the next 25 to 30 year period within the current permitted footprint of the tailings facility.

The Scope of Work for the project was as follows:

• short term planning for the management of the salt tailings; • short term planning for the management of the slimes to remove the slimes from the

top of the salt pile; • identify options for the location of a new slimes disposal facility to provide capacity

for disposal of slime for the design operating period; • evaluation of the potential slimes disposal sites on the basis of environmental,

engineering, operating and economic criteria; • develop a conceptual operating plan for the preferred slimes disposal option for the

design operating period; and, • develop an operating plan for disposal of salt tailings for the design operating period.

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2.0 DESIGN CRITERIA

The design criteria for the operational planning for the PCS Allan Division tailings facility was developed through discussions between PCS Allan Division staff and Golder. In general, the criteria are as follows:

• relocate slimes disposal from the top of the salt pile to an alternate location which will not impact future (long term) development of the tailings facility;

• for the short term operating period, provide capacity for salt and slimes tailings for a three to five year operating period to allow time for siting, design and permitting of a permanent slimes disposal facility;

• the long term planning should provide capacity for salt and slimes tailings for a 25 to 30 year operating period; and,

• the long term plan should allow for further expansion of the facility beyond the design period.

Specific criteria for the operation of the facility are as follows:

• Annual salt tailings production: 2.9 Mt/yr • Deposited salt density: 1.6 t/m3 • Annual salt tailings production: 1.8 Mm3/yr • Minimum design salt tailings disposal capacity: 45.0 Mm3 • Annual slimes production: 0.28 Mt/yr • Deposited slimes density: 1.3 t/m3 • Annual slime production: 0.22 Mm3/yr • Minimum design slimes disposal capacity: 5.5 Mm3

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3.0 LONG-TERM TAILINGS MANAGEMENT OPTIONS

A total of six options for the long term disposal of slimes and three options for the long term disposal of salt tailings at the PCS Allan Mine were developed as part of this study. The combined options for disposal of all waste materials are referred to as follows:

• Option 1: Expansion of the salt pile to the east of the existing salt pile with slimes disposal at the north end of the existing salt pile within the active salt disposal cell;

• Option 2A: Expansion of the salt pile to the north and east of the existing salt pile with slimes disposal to the northeast of the existing permitted tailings facility;

• Option 2B: Expansion of the salt pile to the north and east of the existing salt pile with slimes disposal to the west of the existing permitted tailings facility;

• Option 2C: Expansion of the salt pile to the north and east of the existing salt pile with slimes disposal to the south of the existing permitted tailings facility;

• Option 2D: Expansion of the salt pile to the north and east of the existing salt pile with slimes disposal within the permitted facility to the north of the active salt disposal cell; and,

• Option 3: Provide additional salt capacity by raising the existing pile and providing slimes containment in the existing active salt disposal cell, immediately to the east of the current salt pile.

Details of each of these options as well as an evaluation of the options to select a preferred option are presented in the following sections. The general arrangement of the PCS Allan Tailings Facility is shown on Figure 1.

3.1 Discussion of Options

To date, the development of the salt pile (Figure 2) has been carried out by constructing perimeter berms around the crest of the pile, using salt and discharging the salt slurry onto the pile. This has resulted in a salt tailings surface which slopes from south to north at about a 5 percent slope. In the late 1990’s, a series of cells were constructed on top of the salt for disposal of slimes. The current practice is to discharge the slimes at the south east corner of the slimes cells and allow the slimes to flow to the north.

The proposed decommissioning method for the salt tails is to dissolve the salt and inject the resulting brine into deep saline formations. Continued placement of the slimes of top of the pile will have a negative impact on this proposed decommissioning method. Therefore, each of the options which were identified as part of this study, were developed to allow the slimes disposal to be moved off the top of the salt pile.

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As presented in Section 2.0, the design criteria for the long term operation of the facility is to provide 25 to 30 years of deposal capacity for the salt and slimes tailings at the proposed design mill throughputs. The minimum design capacity for salt disposal is approximately 45.0 Mm3 and for slimes is approximately 5.5 Mm3.

For each of the options, it has been assumed that the initial construction for the slimes cell would be sufficient to provide a minimum of five years disposal capacity. Additional capacity will be developed by expanding the number of cells or raising the perimeter containment dykes as required. For the purposes of this study, it has been assumed that the perimeter containment for the salt discharge will be provided in a manner similar to the current practice: that is using dykes constructed of salt around the crest of the pile to provide the initial containment while the crystalline salt is settling out of the brine slurry.

3.1.1 Option 1

The proposed layout for Option 1 is presented in Figure 3. Cross-sections through the salt and slimes at the end of the operating period are presented in Figure 4.

Option 1 entails construction of a slimes cell immediately to the north of the existing salt pile. The slimes cell would be contained on the south by north end of the salt pile and by perimeter dykes to be constructed around the west, north (following #1 Dyke) and east sides of the facility. For this option, the salt pile was maintained at close to the current maximum pile height of approximately 38 metres. The perimeter containment dykes for the slimes cell will have a maximum height of approximately 20 metres. For both materials, the tailings would be deposited using multi-point spigotting to achieve a relatively planar surface from the area of discharge at any time.

The initial construction for the slimes cell would be sufficient to provide a minimum of five years disposal capacity. For the purposes of this study, it has been assumed that the perimeter containment for the salt discharge will be provided in a manner similar to the current practice: that is using dykes constructed of salt around the crest of the pile to provide the initial containment while the crystalline salt is settling out of the brine slurry.

For the final configuration presented in Figures 3 and 4, insufficient capacity will be provided for both salt and slimes disposal. The slimes cell as shown will have capacity for approximately 20.3 years of operation, while the expanded salt pile would provide capacity for approximately 24 years. The capacity for both streams could be increased by increasing the height of the facility.

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3.1.2 Option 2A

The proposed layout for Option 2A is presented in Figure 5. Cross-sections through the salt and slimes at the end of the operating period are presented in Figure 6.

Option 2A entails construction of a slimes facility to the northeast of the existing salt pile in an area currently used for agricultural purposes. The slimes facility would be constructed as a single cell and would be contained around the entire perimeter through the construction of dykes. Due to the location adjacent to the brine return channel on the east side of the current tailings facility, it would not be possible to utilize the salt pile for partial containment of the slimes on the southwest side. The perimeter containment dykes for the slimes cell will have a maximum height of approximately 20 metres.

For this option, the salt pile was maintained at close to the current maximum pile height of approximately 38 metres. The pile will be extended to the north to the current separator dyke located approximately 200 metres north of the salt pile.

For both materials, the tailings would be deposited using multi-point spigotting to achieve a relatively planar surface from the area of discharge at any time.

For the final configuration presented in Figures 5 and 6, sufficient capacity will be provided for both salt and slimes disposal for the minimum design life. The slimes cell as shown will have capacity for approximately 29.7 years of operation, while the expanded salt pile would provide capacity for approximately 26.9 years. The capacity for both streams could be increased by increasing the height of the facility.

3.1.3 Option 2B

The proposed layout for Option 2B is presented in Figure 7. Cross-sections through the salt and slimes at the end of the operating period are presented in Figure 8.

Option 2B entails construction of a slimes facility immediately to the west of the existing salt pile. The slimes cell would be constructed as a series of three cells which would be contained by perimeter dykes around the perimeter of the facility. The cells would be constructed in stages over the operating life of the facility, with each stage providing approximately five years of disposal capacity. The perimeter containment dykes for the slimes cells will have a maximum height of approximately 15 metres.


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3.1.4 Option 2C

The proposed layout for Option 2C is presented in Figure 9. Cross-sections through the salt and slimes at the end of the operating period are presented in Figure 10.

Option 2C entails construction of a slimes facility approximately 250 metres to the south of the existing salt pile. The slimes cell would be constructed as a series of three cells which would be contained by perimeter dykes around the perimeter of the facility. The cells would be constructed in stages over the operating life of the facility, with each stage providing approximately five years of disposal capacity. The perimeter containment dykes for the slimes cells will have a maximum height of approximately 15 metres. Separate brine handling facilities would have to be constructed for this option.




3.1.5 Option 2D

The proposed layout for Option 2D is presented in Figure 11. Cross-sections through the salt and slimes at the end of the operating period are presented in Figure 12.

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Option 2D entails construction of a slimes facility approximately 250 metres to the north of the existing salt pile, immediately to the north of the current separator dyke. The slimes cell would be constructed as a single cell which would be contained by perimeter dykes around the perimeter of the facility. The perimeter containment dykes for the slimes facility would be constructed in stages over the operating life of the facility, with each stage providing approximately five years of disposal capacity. The perimeter containment dykes for the slimes cell as shown will have a maximum height of approximately 20 metres. Separate brine handling facilities would have to be constructed for this option.



For the final configuration presented in Figures 11 and 12, sufficient capacity will be provided for salt disposal for the minimum design life. However, insufficient volume can be developed for the design slimes capacity. The slimes cell as shown will have capacity for approximately 20.3 years of operation, while the expanded salt pile would provide capacity for approximately 26.9 years. The capacity for both streams could be increased by increasing the height of the facility. However, for the slimes facility, the construction could be difficult due to the foundation conditions which would be encountered within the existing brine pond.

3.1.6 Option 3

The proposed layout for Option 3 is presented in Figure 13. Cross-sections through the salt and slimes at the end of the operating period are presented in Figure 14.

Option 3 entails construction of a slimes cell immediately to the east of the existing salt pile within the current brine pond.. The slimes cell would be contained on the west by the salt pile and by perimeter dykes to be constructed around the north, east and south sides of the facility. The perimeter containment dykes for the slimes cell will have a maximum height of approximately 15 metres.

For this option, the salt pile will be raised to approximately 78 metres in height and will occupy the existing footprint of the main salt pile.

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For the final configuration presented in Figures 13 and 14, sufficient capacity will be provided for salt disposal for the minimum design life. However, insufficient volume can be developed for the design slimes capacity. The slimes cell as shown will have capacity for approximately 20.3 years of operation, while the expanded salt pile would provide capacity for approximately 26.9 years. The capacity for both streams could be increased by increasing the height of the facility. However, for the slimes facility, the construction could be difficult due to the foundation conditions which would be encountered within the existing brine pond.

3.2 Evaluation of Options

Each of the options were evaluated on the basis of the following major criteria with sub-criteria within each category.

• Environmental Impact - Disruption of habitat - Disruption of water resources - Visual impact

• Operations - Pumping requirements - Pile height / stability - Brine Handling - Flood Storage - Employee Health & Safety

• Economic - Cost of construction (Capital) - Operating Cost

• Decommissioning Requirements - Potential for progressive reclamation

The options were evaluated relative to the other options. For example, for the economic criteria, the lower cost options would score higher relative the higher cost options.

3.2.1 Environmental Impact

All of the options identified have no impact on any native habitat or surface water resources. A brief review of available borehole logs in the area of the tailings facility indicates that there is limited potential for near surface ground water resources in the area of the salt pile.

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The primary impact from the development of each of the options will be visual impact. Option 1 will require an increase in pile height to provide the design capacity for salt and slimes. All of the Options 2 will have the same ultimate salt pile height. However, due to the location of the proposed slimes cells, Options 2A, 2C and 2D will have an increased visual impact compared to Option 2. Option 3 will have the largest visual impact due to the required pile height to provide the design disposal capacity.

3.2.2 Operations

Due to the maximum pile heights and locations and heights of the slimes cells, the pumping requirements for Option 1 and Options 2A to 2D will be approximately equal. Due to the pile height, Option 3 will have significantly higher salt tailings pumping requirements throughout the operating period than the other options

Pile 3 will also have the greatest potential for reduced pile stability due to the increase in pile height required. Option 1 will also require a higher salt pile to provide the necessary salt disposal capacity, but the modest increase required should have minimal impact on the overall pile stability.

Option 1 and Option 2D which require development of the slimes storage at the north end of the salt pile will require modifications to the brine handling for brine coming off the salt pile. Channelization of the brine discharge or a pumping system will be required for these two options. In addition, separate brine handling facilities will be required for the Option 2C slimes facility due to its location away from the existing tailings facility.

Option 2D will require construction of the slimes facility in the north pond which is currently used for flood storage. Therefore, a significant part of the flood storage will not be available for this option.

Employee Health and Safety will become an issue as the height of the salt pile increases or in situations where employees may have to drive on narrow dykes near open water bodies for inspection of the facilities. Safety of mine and contractor staff may also be an issue for the options where construction is required within the existing pond areas. Option 1, Option 2D and Option 3 will have disadvantages with respect to the other options for employee Health and Safety.

3.2.3 Economic

The capital cost of construction will be significantly impacted for options where total perimeter containment must be provided, or where construction must be completed in difficult construction conditions (i.e., within existing ponds). Options 1 and 3 will likely

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have the lowest capital costs, while options 2A, 2C and 2D will likely have the highest capital costs.

Operating costs for the facilities will be mainly impacted by pumping costs. Option 1 and Options 2A to 2D will have similar pumping costs. Pumping for Option 3 will be significantly higher throughout the life of the operation due to the height of the salt pile.

3.2.4 Decommissioning

The proposed decommissioning method for the salt tailings is to dissolve the salt and inject the resulting brine in deep saline aquifers. Therefore, the decommissioning of the salt pile for each of the options will be relatively similar for all options.

The slimes will be decommissioned on surface. Options where the slimes disposal facility is developed as a series of cells will allow for progressive reclamation over the life of the facility as the cells are filled. Options 2B and 2C will allow for progressive reclamation of the slimes facilities.

3.3 Preferred Option

A summary of the evaluation is presented in Table 1. In Table 1, a dash indicates that the option is approximately equal to the average of the other options, a check mark indicates that the facility would rank higher than the other options and a ‘X’ indicates that the option would rank lower than the other options.

As can be seen in Table 1, Option 2B ranks relatively high when compared to the other options. For all evaluation criteria, Option 2B is either equal or superior to the other options.

On the basis of the above evaluation, Option 2B is the preferred alternative for long term operation of the PCS Allan tailing facility.

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Table 1 Evaluation of Options

Option 1 2A 2B 2C 2D 3

Potential Environmental Impact • Habitat Disruption • Water Resources • Visual Impact

--

Operations • Pumping • Pile Height/Stability • Brine Handling • Flood Storage • Employee H&S

-- --

--

-- -- -- --

-- --

--

-- --

--

-- --

-- --

Economic Considerations • Capital Cost • Operating Cost

--

--

-- --

--

--

Decommissioning • Progressive Reclamation

--

--

--

--

Legend

= Ranks better than average of other options -- = Ranks comparable to average of other options X = Ranks lower than average of other options. favourable for category ↕ unfavourable for category

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4.0 SHORT TERM OPERATIONAL PLANNING

The Short Term operational plan for the PCS Allan tailings facility has been developed to have no impact on the long term operation of the preferred salt and slimes facilities. One of the primary objectives of the Short Term plan is to develop an alternate location for disposal of slimes produced during the on-going operation of the tailings facility, to facilitate moving the slimes disposal off the top of the existing salt pile. The facility for short term operation of the slimes should also have no impact on the long term operation of any new slimes containment facility or the expanded salt pile.

A number of options for relocation of the slimes cell were identified within the existing permitted tailings facility. However, all of the identified locations are in areas of existing brine ponds, and would have very difficult construction conditions. In addition, any options within the existing facility may have a significant impact on the foundation conditions for future salt pile expansions.

A site for the short term slimes cell was selected in the northeast corner of the preferred site for the long term slimes facility. The facility is sized to provide a minimum of two to three years slimes disposal.

The proposed short term slimes cell will provide benefits to the long term disposal of salt tailings by removing the future deposition from the top of the pile. This should reduce the potential for future stability issues should it be necessary to raise the height of the pile in future. In addition, the construction of the cell will provide the opportunity to conduct further research into the operation of the ultimate facility. In particular, it will provide an opportunity for full scale validation of the test work currently underway at the PCS Lanigan Division.

The research programme which will be carried out as part of the short term operation will include:

• assessment of deposited slimes and natural soils for brine containment; • installation of instrumentation to evaluate the characteristics of the slimes and brine

migration; • evaluation of the number and location of filter zones required in the perimeter

containment to allow drainage of the slimes and to provide clear brine; and, • trials of multi-point spigotting of the slimes.

Figures 15 through 17 show the proposed development of the pile during the short term. Figure 18 shows sections through the salt pile at various times through the development

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of the short term plan and the proposed slimes cell at the end of the short term operating period.

The research will be carried out using sub-aerial deposition techniques. For the research program, slimes will be deposited in the cell using multi-point spigotting. The cell will be operated to maintain the minimum pond of water possible, to promote consolidation of the slimes.

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5.0 LONG TERM OPERATIONAL PLANNING

The long term operational plan will result in an expansion of the salt pile to the east within the existing permitted tailings facility. The slimes facility located to the west of the salt pile will be developed as a series of cells over the operating life of the facility. Figures 19 through 26 show the proposed development of the salt pile and the slimes facility at various stages in the operating life of the facilities.

As shown on Figure 19, deposition into the salt pile expansion area would commence shortly after the end of the short term operating period three years. This change in location of salt deposition could be delayed by continuing to raise the west side of the salt pile towards the north end.

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Golder Associates

6.0 CLOSURE

We trust this report presents the information you presently require. Should you require additional information, please do not hesitate to contact us.

GOLDER ASSOCIATES LTD. Leon C. Botham, M.S.C.E., P.Eng. Associate, Senior Geotechnical Engineer Gregory A. Misfeldt, M.Sc., P.Eng. Associate, Senior Geotechnical Engineer

LCB/GAM/pls

Golder Associates

FIGURES

MAINPOND

#7 DIKEACCESSROAD BRINE

RETURNCANAL

PUMPHOUSEPOND

TAILINGSPILE

MINESITE

HWY397

NEW BRADWELLROAD

OLD BRADWELL ROAD

#4 DIKE

#4A DIKE

DRAINAGEDITCH

#2 DIKE

#5 DIKE

SPILLWAY

#1 DIKE

#6 DIKE

#7 DIKE

NORTHPOND

GENERAL ARRANGEMENT PLAN

FIGURE: 1REFERENCE :BASE PLAN PROVIDED BY THE POTASHCORPORATION OF SASKATCHEWAN, ALLAN DIVISION

PERMITTED TAILINGSAREA BOUNDARY

NOTES:1. AIR PHOTO AND TOPOGRAPHIC DATA PROVIDED BY POTASH CORPORATION OF SASKATCHEWAN.TOPOGRAPHIC MAPPING CONDUCTED IN 2004. AERIAL PHOTOGRAPHY COMPILED IN 2005.

EXISTING CONDITIONS

FIGURE: 2


A-

A'-

B-

B'-


OPTION 1 - FINAL TOPOGRAPHY

FIGURE: 3

SALT PILE AREASALT PILE HEIGHTSALT VOLUMESLIMES CELL AREASLIMES CELL HEIGHTSLIMES VOLUMEPERIOD OF OPERATION

270 ha~38 m

43.28 Mm³32 ha~20 m

4.45 Mm³20.3 YRS

OPTION 1 - CROSS SECTIONS

FIGURE: 4

5x VERTICAL EXAGGERATION

ORIGINAL GROUNDLEGEND


E-

E'-

D-

D'-

C-

C'-


OPTION 2A - FINAL TOPOGRAPHY

FIGURE: 5


302 ha~38 m

43.52 Mm³61 ha~20 m

6.54 Mm³26.9 YRS

OPTION 2A - CROSS SECTIONS

FIGURE: 6




D-

D'-

C-

C'-

F-F'-


OPTION 2B - FINAL TOPOGRAPHY

FIGURE: 7


302 ha~38 m

48.52 Mm³92 ha~15 m

6.40 Mm³26.9 YRS

OPTION 2B - CROSS SECTIONS

FIGURE: 8




D-

D'-

C-

C'-

G-

G'-


OPTION 2C - FINAL TOPOGRAPHY

FIGURE: 9


302 ha~38 m

48.52 Mm³84 ha~15 m

6.79 Mm³26.9 YRS

OPTION 2C - CROSS SECTIONS

FIGURE: 10



3.5 Hydrogeology 3.5.1 Hydrostratigraphy 3.5.2 Aquifers

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