This necessitated ballasting, to avoid pitch problems, and a tilt test, to check stability. Additional ballasting of the piers was also needed. The list was corrected by ballasting the ship. Aggregates can form through abiotic processes i.e. ballasting and biotic processes i.e. extrapolymeric substances(EPS). The largest of these was a Y-class locomotive that was used on ballasting runs. By 1908, ballasting and plate laying had reached Kiwi station. This means that by ballasting, they can submerge their cargo holds. This included clearing, preparing the track bed, tracklaying and ballasting. Ballasting the bow greatly improves operation under power. Although heavy ballasting will prevent passive ascent, Beaune et al. A ballasting system is fitted to allow for safe operations during loading. The ballasting was of gravel, of at least 2 feet in thickness throughout. In 1997, bonding and ballasting of the brick vaulting was undertaken as a seismic upgrade.