Historic exploration at Lochinvar was conducted in the 1950’s by the National Coal Board, which sank four boreholes. This work proved the existence of the same sequence of thick coals of the Middle Coal Measures, which had been previously mined at Rowanburn colliery to the east of the licence where operations ceased in 1922.
From 1979 the NCB drilled a further nine boreholes and shot 55 kilometres of seismic line which proved the existence of a large concealed coking coalfield (the Canonbie Coalfield). The geological and mining potential of the coalfield was summarised by G.S. Picken, coal geologist with the British Coal Corporation in his 1988 paper “The concealed coalfield at Canonbie: an interpretation based on boreholes and seismic surveys”.
NAE’s consultants, SRK have reviewed the previous exploration and geology of the Lochinvar Project and have produced the seam contour plan shown in Figure 3.
Including the Six Foot, Nine Foot, Five Foot and Black Top seams, the project has a conceptual exploration target of 330 to 410 million tonnes, with 4% at depths less than 200m, 22% between 200m and 400m deep, and 20% between 400m and 600m deep. Figure 4 shows indicative cross sections at two different orientations through the Lochinvar deposit.