Evaluation of the impact of reclamation regulations and guidelines on ecological rehabilitation practices at the Estevan surface coal mines (1996-1999), Saskatchewan.

Luscar Ltd. is required by law to submit a pre-mining and reclamation plan and a proposal for an assurance fund to SE to ensure the decommissioning and reclamation of mining sites. Commenting on the mine plan, an official of SE observed that Luscar Ltd. sets out its reclamation plan in March of every year. Draft plans for mining and restoration and the assurance fund which have been submitted by the management of Luscar Ltd. since 1996, have met standards stipulated in the 1996 regulations and have consequently been approved by the Minister of Environment, Saskatchewan. An interview with SE regulators revealed that the mining company has not defaulted in observing the requirements of the assurance fund. The fund provides security against breach of the permit conditions and rehabilitation requirements.

In order to monitor rehabilitation success, the mining company is required to conduct field evaluations and submit semi-annual reclamation reports to SE. The mining company submitted eight reclamation reports between 1996 and 1999. The reports, supported by air photos, maps and soil and plant surveys, illustrate hectares for which various reclamation steps were undertaken, timing of all reclamation activities, soil amendments applied and the results of seeding. These reports have been reviewed and endorsed by SE officials.

Site-specific Restoration Programs

The issue of environmentally responsible mining in the Estevan area is not whether the mine site will be restored, but the manner in which restoration is accomplished. Luscar Ltd. is required to take measures in dealing with and lessening the environmental impacts of coal mining operations. An interview with officials of Luscar Ltd. revealed that coversoil removal is normally conducted annually, during the unfrozen conditions (summer), and takes place approximately six months ahead of mining.

Currently, coal is mined by a 1,570W Bucyrus-Erie dragline, the Prairie Queen, and 'Big Lou', a giant dragline (MacBean 2001: 4) in a series of parallel cuts--30 m wide strips up to 3.5 km in length. Following coal removal, these pits are subsequently backfilled and reclaimed in a regular manner: reclamation is done simultaneously with mining operation. Overburden excavated from the active cut is used to backfill the pit which is subsequently levelled. In line with the rehabilitation plan, part of the spoil piles of mining has been levelled to the required slope. Soil surveys undertaken by the mining company at the Bienfait, Boundary Dam and Utility Mines indicate that topsoil (A-horizon) materials with depths averaging 10-15 cm are found over the pre-mined lands. The stockpiled soil is then spread on the levelled area and seeded. A selective overburden handling technique' has been incorporated into rehabilitation work at Bienfait, Utility and Boundary Dam mines. According to mine officials, the technique selectively places overburden materials with higher reclamation suitability into the upper portion of the backfill of the mined lands (Luscar Ltd. 1996-2000). Overburden materials (B-horizon) that are not suitable for plant growth are buried deep in the backfilled area.

Site levelling and grading operations are undertaken by bulldozers, scrapers and graders, with the objective of creating 10% slope and a landscape acceptable to the proposed soft land uses: typically agriculture (cropping), wildlife and recreation. Initial box cut and final mine cuts normally retain greater slopes (10 to 20%). An environmental planner of Luscar Ltd. indicated that after coversoiling, the disturbed lands receive another lift in volume, which adds up to approximately 15 cm in thickness after grading and compensates for the metre of coal seam removed. According to the Guidelines, grading of land should occur within two years of the initial disturbance (Luscar Ltd. 1996). Yet, soil replacement on parts of the mine sites of Bienfait, Boundary Dam and Utility mines occurred within three years of initial disturbance. In cases where cover soil was not available at a particular site, engineers resorted to using other alternatives such as transferring cover soil from other sites (Estevan Coal Corporation 1996) instead of using suitable substrates such as residual hay, straw or wood chip. Unless such 'supplier sites' have enough top-soil to offset the deficiency, this practice can have adverse long-term consequences such as nutrient depletion and low vegetative growth.

Revegetation of graded land for agriculture, rangeland and wildlife is a significant part of ecological rehabilitation practices in the Estevan area. Emphasis has been placed on quickly establishing vegetation to control erosion and to achieve a self-sustaining plant cover. Officials of Luscar Ltd. work in close collaboration with personnel of SaskPower's Shand Greenhouse who currently conduct revegetation in the Estevan area (SaskPower is the final custodian of most of the rehabilitated lands in Estevan and owns the coalfields, which are leased to the mining companies for mining operations). In 1999, germination trials were conducted at the greenhouse on five rare native species for Luscar Ltd., including purple coneflower (Echinacea), bird's foot trefoil (Lotus corniculatus), milkwort (Polygala verticillata), salt bush (Baccharis halimifolia) and whorled milkweed (Asclepias syriaca). These species have been used in seeding programs in the Estevan area with 50% survival rates (Luscar Ltd. 2000).

In addition, measures were undertaken to prevent the transfer of contaminated water into the underground water systems and Souris River--the main river that drains the area. The SE-approved dewatering procedure was followed. There was no water discharge from surface impoundment and settling ponds at the Boundary Dam Mine between 1996 and 1997. However, between 1998 and 1999, a total of 899,208 m3 of water was pumped from dewatering wells and settling ponds to approved discharge points. Some of the water was discharged into SaskPower's Shand Cooling Tower in 1999 (Luscar Ltd. 1999). Since this is a closed system, there was no water quality analysis. Quality analysis was, however, conducted on the remaining two-thirds of water discharged during the period. Water samples were collected once a week and analyzed for turbidity and suspended solids (TSS). The average TSS was 28.5 mg/l which was below the legally allowed maximum level of 50mg/l (Table 1). The average TSS for water tested at the Bienfait mine (total of 368,340.6 m3) between 1996 and 1999 was 19.8 mg/l which was below the legally allowed maximum limit of 50 mg/l set by the SE guidelines (Luscar Ltd. 1999). There was no water discharge from settling ponds in 1996, 1997, 1998 and 1999 (Luscar Ltd. 1996, 1999) at the Utility Mine because settling ponds and wells were not in use.

A comparative study of the three sites revealed that a total of 734.81 ha were mined between 1996 and 1999 in the Estevan area. Out of this figure, 444.03 ha have been successfully reclaimed and decommissioned (Table 2). Thus, 60% of the total area disturbed has been levelled to the acceptable slope of less than 10%. The proportion of levelling is an improvement over the situation that existed before the 1993 Guidelines were developed when virtually nothing was done. However, there was a shortfall in the rate of seeding. Only 17% of the total area disturbed has been seeded which is equivalent to 29% of the total area levelled. The problem is attributed to the harsh climate and soil conditions of the area as well as equipment problems. Nevertheless, portions of the three sites met SE's minimum standards and the mining company has been released from further responsibilities of restoration on these lands.

Overall, Boundary Dam Mine recorded the largest area mined between 1996 and 1999, accounting for 46% of the total area disturbed. Similarly, the area rehabilitated was the highest of the three sites studied. This was due to the commitment of more equipment and personnel to rehabilitation activities during that period, as compared to the other sites. Between two and five bulldozers were used in restoration practices depending on the site-specific requirements of the area. An equal number of personnel was also employed. The Utility Mine recorded the second highest rate of disturbance after Boundary Dam Mine (Table 2). Out of the total area of 208.41 ha mined at the Utility Mine (1996-1999), 136.97 ha have been successfully graded accounting for 31% of total area levelled in the Estevan area.

Table 2 provides a comparison of the rates of disturbance, leveling and seeding among the three mine sites. Bienfait Mine recorded the least amount of area mined (189.13 ha) and restored during the period. The area levelled at the Bienfait Mine accounted for 29% of the total area levelled in the Estevan area. Aerial orthophoto map interpretation confirmed the spatial-temporal variation in the rate of disturbance and rehabilitation at the Boundary Dam, Utility and Bienfait Mines over the years. About 60% of the levelled areas met SE's standards and were released from reclamation obligations. SE inspectors consider the overall rate of leveling as average.

Local Residents' Perceptions of Ecological Rehabilitation