Investigating the Impact of Concrete Driven Piles on the Archaeological Record Using Soil Micromorphology: Three Case Studies from the Netherlands

Abstract

In this paper we present the results of field tests into the impact of driven concrete piles on three archaeological sites in the Netherlands. The field tests were done in two different types of archaeological sites. Two locations in the northern part of the Netherlands (Kenwerd and Groot Wetsinge) were artificial mounds or terps, where new buildings were going to be constructed using driven piles. The third location was Voorburg in the western part of the country, where the impact of pilings from the 1950s were studied. We analysed soil which was in direct contact with the piles, and soil at a distance from the pile surface.

The tests show remarkable results. Visible effects of piling in sand were downdrag of sediments along with the pile, disturbance of structure by local displacements, or liquefaction. In clay, some disturbance of structure, compression of pores, and damage to carbonized material was observed. Additionally, piles may promote the formation of pyrite in the directly adjacent peat. In a large number of samples taken from soil directly adjacent to a pile, no disturbance was observed. We did not observe any impact further than six to eight cm from the pile surface.

These results indicate that the impact of piling in fine sediments is smaller than is generally assumed. However, as the number of observations in the present study is relatively small, the results need to be corroborated by more field tests. In future, planners need to consider the direct effects piles have on the surrounding soil as well as the possibility of excavations.