C O N T E X T 9 9 : M A Y 2 0 0 7 29 Ian Hume Serious settlement and a light touch Even when a building is suffering from serious structural problems, creative engineers can avoid compromising its historical and architectural value. The village of Whitgift sits on the south bank of the Great Ouse about four miles east of Goole. It is a small, strung-out sort of place of only a few dozen houses, the church and no pub. As soon as you drive into the village you are made aware of severe settlement problems: many of the houses sit at rather odd angles.The church is no exception. It has a distorted tower and, until recently, walls with a multiplicity of major fractures. There is only a high embankment and a road between the river and the churchyard.The surrounding ground level is pretty much at river level, the river being tidal at this point. History tells us that the previous church, having suffered flooding on numerous occasions, was finally abandoned and demolished in the 1240s. Even the clock is odd: it goes from 10 to 11 to 13.Whatever happened to 12 o’clock? Shallow trial holes showed nothing really unusual for a church that was originally built in the early 1300s: shallow footings, not much wider than the walls, on reasonable ground. But clearly something was amiss with the church and the ground on which it sits, so a deep borehole was drilled. This showed that the top two metres consisted, as shown by the trial pits, of firm, disturbed clay. However, this was sitting on very soft, peaty clay, which in turn sat on 1.5 metres of peat. Below this was 5.5 metres of clay, which varied from soft at the top to firm lower down. Lower down still there was 5.5 metres of loose, silty sand. Not until 15.5 metres down was there stiff clay, the sort of soil which today we might think as being suitable to support a building. All in all, it was a bit like putting a building on a rice pudding. Careful structural monitoring over a 12 month period showed continuing movements, with a number of readings showing about one millimetre of movement. The continuous and steady widening (rather than cyclical) movement was of at least as much concern as the total width of the fractures. To some extent monitoring was somewhat academic: very clearly some action needed to be taken. The church has many fractures, a great deal of distortion and some arch stones threatening to drop out. As is often the case with a rural parish, it has few worshippers and therefore not a great deal of money. Partial underpinning in the traditional sense is almost always to be avoided. In fact, traditional underpinning with dense concrete on such poor ground would probably result in the church sinking even faster, due to the extra load on very soft ground. A rough estimate of the cost of complete underpinning with piles to a depth of about 17 metres was given as £500,000. Although the small congregation and many of the villagers were very enthusiastic about seeing their church put into good order, that sort of money would be completely out of reach. A further scheme for ground consolidation was looked into but there was no guarantee that it would work.What was to be done? Often the congregations of churches that have much less severe movement are told that, while ensuring that nothing is left to become a health and safety risk, the best way of dealing with settlement is to carry out basic repairs, and to accept the fact that small fractures will reappear from time to time. Continuing movement will have to be accepted as being the only sensible and affordable option. However, the movements atWhitgift are very significant, so accepting the reappearance of fractures after repair would have considerable impact. The scheme that was devised might be described as basic repairs plus crack control. The worst areas of damage have been taken down and rebuilt with specially designed movement joints. When movement happens, as it undoubtedly will, the building should crack in predicted, safe and not unsightly ways. The north face of the tower of the church of St Mary Magdalene, Whitgift. The string course is level, even though the bed joints of the lower stage are not. Typical cracking on the east wall of the south aisle
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