Filled with gravel

Despite some of these other topics, the major exercise of ground works on the HBA array is continuing. With the main site area roughly levelled, the crew are now bringing in loads of fine gravel. This is a very uniformly graded material, with each piece being about 15–20mm in size. In the first photograph, you can see the lorry dumping out another couple of piles of the material.

The gravel is designed to be porous. One of the issues for the site is that water drains away quickly. What can happen is that in spring some freak warm weather can cause a sudden snow melt, which could bring a log of sudden meltwater. Additionally, the surface of the tiles will channel the water into certain locations, so we need to be able to cope with that. (There's another trick we've got, but that will be for another web log post!)

Once the gravel is down, the 18-tonne digger is used to spread it out uniformly over the field. It is slow work, but the team are doing a very high-quality job.

Photos: D. McKay-Bukowski