Technological field investigations have continued at two potential hydro sites, at the smelter site on Maniitsoq Island and in the transmission line areas.
Hydro Sites (7e—Tasersiaq and 6g—Tarsartuup Tasersua)
Shallow and deep boreholes have been drilled on the powerhouse locations, as well as in the proposed dam locations. The geotechnical borings allowed the collection of information on rock quality, in situ stresses, orientation of the powerhouse and dams, locations and length of tunnels, and the permafrost risk. The results will be incorporated into the cost estimate for the quantity of materials needed to build these civil works.
Borrow Source Mapping
Several possible borrow sources have been identified near each proposed dam alignment. Collected data will be used to help interpret the depth to rock, identify areas with permafrost, determine rock quality, identify areas exhibiting anomalous rock qualities (i.e., fractured and weathered zones) and calculate the engineering properties (material strength and stiffness) of materials at depth. The test pits also will confirm excavation assumptions and help indicate if any of the natural/existing in-country resources can be utilized.
Mapping of joint sets, faults, intrusions and rock types was completed in selected project areas. The coast of Lake 860 at Site 7e was also surveyed, and any pertinent geology was noted.
Bathymetry was performed by ship in the fjord outlets at the two hydro sites and at the transmission line crossing area by Maniitsoq. The surveys are rough (5- to 10-meter contour intervals) for most of the fjord locations. The power tunnel outlets and the Maniitsoq crossing areas have 2-meter contours. These surveys were completed in March and the data were processed by July.
Asiaq performed bathymetry on the inlet lake at Site 7e. These studies were performed during the spring of 2009 and have 5-meter accuracy.
Lake Temperature Measurement
Asiaq installed thermistor strings at the inlet lakes for sites 7e and 6g. These strings were attached to data loggers and include satellite links to monitor the water temperature of the lakes at various depths on a year-round basis.
Asiaq performed flow monitoring at Site 6g and additional measurements at Site 7e. The flow series will be used to confirm the available power and geometry of all the civil works, which will allow a more accurate cost estimate.
Geotechnical Borings and Probes (smelter and port locations)
A total of 14 shallow geotechnical borings, both on land (smelter site) and over water (proposed pier), were completed at the proposed smelter site during the summer 2009 field season. Soil overburden encountered was sampled for chemical analysis. Also, shallow probes were performed at the proposed smelter pier location.
Additional Tests on 2008 Rock Core
The remaining rock core from the 2008 smelter borings was tested as aggregate material. The testing included physical and chemical durability tests to prove that the rock at the smelter site will be acceptable as fill and for use in concrete and asphalt.
Fresh Water Bathymetry and Water Testing
Asiaq performed bathymetry on one freshwater source on Maniitsoq Island near the proposed smelter. The bathymetry was completed so that a 2-meter contour map can be made for each lake. The lake volumes will be combined with water collection rates calculated by the smelter group to evaluate if enough freshwater can be collected in the lakes to provide all water needed for the smelter.
Asiaq also collected water samples from the freshwater source. The samples will be tested (chemical analyses) to ensure that the water is safe to be used as drinking water based on Danish drinking-water regulations. The samples will also be used to determine if the water meets all of the smelter needs.
Sea Ice Study
The sea ice was observed in the area around Maniitsoq and studied historically. This preliminary study will help the team understand the amount and movement of ice throughout the year, and how it would affect ship travel to and from the smelter site.
The project areas were visited in April to measure snow depths and identify any avalanches that occurred near the proposed transmission line alignments. EFLA Consulting Engineers returned to the area in August to refine its alignment of the power lines (beyond that carried out in 2008), identify the best positions for the towers, estimate the permafrost locations, investigate road alignments needed for transmission line construction and maintenance and collect additional data from the test spans erected during 2008.
Overall, the line paths can be selected where risks from heavy icing and wind on conductors, snow avalanches, flooding and drift ice on towers can be managed by countermeasures. The line routes will be modified for greater optimization to minimize risk and associated cost.