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 be technically extracted. According to the TNO report Regional Soil Opportunities Map South Holland (December 2000), there are major differences in the thickness of the recoverable concrete and masonry sand. The largest 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 recoverable sand reaches between 15 and 35 meters. To the northeast of Leiden, the concrete and masonry sand in the winable package also reaches large thicknesses (15 to 35 meters). In the rest of the research area, the thickness of the concrete and masonry sand varies largely between 0 and 15 meters. In parts of the province there are insufficient hard data to make a statement about the thickness of the recoverable packages of concrete and masonry sand, especially northeast of the Zevenhuizerplas and in the northeast of the province. Contiguous clay, clay and peat layers have not been found in the winable package. Locally occur in the recoverable package of gravel layers, which can reach a thickness of a few meters. To the west of the line Alphen aan den Rijn — Capelle aan den IJssel — Strijen — Layers with shells appear in the winable package. In general, the shell content of these layers is not high. The thickness of the covering package in South Holland increases from east to west from about 4 meters to more than 20 meters.