Underpinning St Marys Church, Gt Eversden
Project : Diamond Drilling holes in flint church wall for underpinning
Location: St Marys Church, Great Eversden, Cambridge
Client: Bakers of Danbury
Drill Masters were contracted by Bakers of Danbury to diamond drill holes in flint walls through the church walls allowing the church to be underpinned due to it subsiding which is causing the walls to crack.
The church at Great Eversden has been there since at least 1092, and dedicated to St Mary since the 13th century. The current church was completed in 1470, consisting of a chancel, nave with north porch and a west tower.
The aim of this project is to float the church from the clay ground so that it is not affected as the clay soil moves. This is achieved by drilling concrete pile caps 9m down into the bedrock ground around and inside the church. These pile caps are not affected by movements in the clay surface soil. Once the pile caps were bored and in place Drill Masters were required to diamond drill below ground level 12 No. 400mm x 400mm square holes in flint walls through the church for RSJ steel beams to then be inserted through the walls and these RSJ beams support the church walls. The thickness of the church walls was calculated at being 800mm thick and made up of flint and limestone. In total only 7 no of these openings were through 800mm flint and limestone rubble walls the other 5 no were through 1.2M thick heavily reinforced concrete walls. This was due to the north side of the church being underpinned during the 1980s.
The project expanded on its original brief due to the discovery of the underpinning resulting in the project taking a greater length of time to complete and costing a considerable higher sum than anticipated. Drill Masters Ltd continue to drill diamond holes in flint concrete walls and they await further instruction on how the underpinning is going to progress.