Concrete and masonry sand

Primary and secondary extraction of concrete and masonry sand is limited to those areas where there is sufficient coarse sand that can technically be extracted. According to the TNO report Regional Soil Opportunities Map South Holland (December 2000), there are major differences in the thickness of the extractable concrete and masonry sand. The greatest thicknesses (20 to 40 meters) are found in an elongated strip that runs from the Alblasserwaard, the Krimpenerwaard, the Zuidplaspolder, the surroundings of Pijnacker and Delft to Rijswijk. In an elongated strip from Bodegraven to Leidschendam, the extractable sand reaches thicknesses of between 15 and 35 metres. Northeast of Leiden, the concrete and masonry sand in the extractable package also reaches great thicknesses (15 to 35 metres). In the rest of the research area, the thickness of the concrete and masonry sand largely varies between 0 and 15 metres. In parts of the province, there are insufficient hard data to make a statement about the thickness of the extractable concrete and masonry sand packages, particularly northeast of the Zevenhuizerplas and in the northeast of the province. Contiguous loam, clay and peat layers were not found in the extractable package. Locally, the extractable package contains layers of gravel that can reach a thickness of several metres. To the west of the line Alphen aan den Rijn - Capelle aan den IJssel - Strijen, layers of shells occur in the extractable package. In general, the shell content of these layers is not high. The thickness of the covering layer in South Holland increases from east to west from approximately 4 meters to more than 20 metres.