Going below to protect the above

Standing since medieval times, the famous Lincoln Cathedral in the United Kingdom provides some of the most remarkable architectural elements in the British Isles. Records show Saxon houses from the 12th to 17th centuries within the church’s courtyard. Along with these elements comes many buried archaeological relics dating back to the construction in 1072.

As the cathedral prepares to undergo renovations to develop a new refectory and visitor facilities, planners needed to ensure no historical artefacts could be harmed during the process. They turned to Technics, a geospatial consultancy specialising in building and utility surveying across the U.K.

Looking below

Technics carried out a Ground Penetrating Radar (GPR) survey at the historic cathedral to provide detailed subsurface data to detect both archaeological and utility features.

The GPR data has been used to support the development plans, and, most importantly, minimise the risk of damage to any buried archaeological evidence as well as plot the position of known and unknown utilities.

Technics used a suite of GPR systems by IDS GeoRadar. This included the RIS MF Hi-Mod, a specialised GPR system capable of investigating large areas to produce a 3D view, and the new Stream C, the company array solution for real-time 3D mapping of underground utilities and features. Technics captured multiple 3D data sets in high resolution for post-processing the detectable utilities and archaeological features.

“We were very excited to employ the suite of IDS GeoRadar equipment we have on site including the new Stream C. Processing the results in GRED HD enabled our team to view the data sets in three different views – tomography, cross sections and in 3D," said John Macintyre, Technics managing director. "The result was highly effective in highlighting a mass of deeply buried Roman walls and clear evidence of the medieval Deanery in the area of the proposed visitor facilities."

Protecting history

Having carried out the detailed survey, Technics was able to compare the GPR data and evidence from boreholes, which included traces of Roman tiles, ceramics, plaster and tesserae. Analysis of the GPR data revealed the positions of a series of probable structures, including parts of Roman, post-Roman and medieval buildings.

These results will now enable the planned works with prior knowledge to minimise damage to the historical elements. Cathedral officials can now also instigate appropriate recording programmes for archaeological features that cannot be avoided during development.

“The GPR survey to the north of the Cathedral revealed the traces of the Medieval buildings where we expected them, but much more vital and interesting, it showed a mass of deeply buried Roman walls beneath them in the area where the new shop, museum and restaurant were designed to be built,” said professor Dominic Powlesland, Lincoln Cathedral archaeologist consultant. “Finding this out at an early stage has been crucial in allowing modifications to the plans within a scheduled area, which would otherwise have been ruinously expensive once the project got underway.”