Using a scraper to clean a sediment core taken from a sand filter

Using a scraper to clean a sediment core taken from a sand filter. The aim is to remove surface sediment that may have been displaced when the core was opened and eliminate the small PVC or aluminium shavings dislodged when cutting the tube. This operation is essential to ensure the quality of the analyses to be performed later. The sand filter here is a water purification device located under the Quai de la Madeleine in Orléans. The device filters some 7 million cubic metres of wastewater and rainwater from the north of the city which is then channelled to treatment plants downstream. The conical basin is 17 m deep and is entirely buried underground. The sediment accumulated since the construction of the basin in 1942 will help researchers reconstitute more than 70 years of local history. The renovation of the sand filter was the perfect opportunity to take core samples of the sediment and examine its content.