Walmer Castle dates back to the 15th century, originally constructed as a Tudor fortress by King Henry VIII between 1539-1540. The castle’s conservation woodlands are much older than the castle itself and span 8 acres.
As part of
its plans to rejuvenate the walking routes around the historic pleasure grounds, and in particular the planted former chalk quarry called the Glen, English Heritage identified one pathway as being dangerous and on a steep slope. To address this, it was proposed to build a brand new staircase with limited impact on the surrounding area.
As this area is of historical importance, any work needed to be in accordance with strict guidelines for listed buildings and conservation areas. Specialists from Target Fixings were contacted to ensure that the method of work would be sympathetic to the surrounding conservation area before any work was carried out.
It was agreed that Target’s 100mm diameter Heli Pile® foundation system would be installed at 12 positions, including specially designed “top hats”, to create a series of level, concrete-free pads that provide a supporting base for the new staircase.
The Heli Pile was originally designed to offer a cost-effective solution for subsidence, particularly in areas where access is limited. Heli Pile has since been used in many varied applications, from crane davit supports for the Canal And River Trust to concrete-free foundations for modular classrooms. In particular, the Heli Pile was chosen because of its ability to be used in areas guarded by tree protection orders.
Each Heli Pile was installed by Target’s installation arm, Target Structural, using a hand-held pneumatic hammer driver, without any need for soil augering, resulting in very little muck away or special access provisions. After installation, each Heli Pile was proof tested in tension on-site in situ to achieve a 5 kN load. This testing procedure allowed the capacity of the pile to be proven on-site without a requirement for any heavy equipment - the compression capacity is at least 20% higher than the tensile capacity.
Edward Hall, director of Target, said: “It is a special privilege to be able to provide solutions for historic buildings and conservation areas, and also to have access to areas in these properties and grounds that generally remain secret. We are fortunate to have been involved with projects of this prestige for over 20 years, designing, supplying and installing solutions for difficult to solve challenges!”
