AN investigation has revealed that the blockage of a sewer pipe at Gyllyngvase has been caused by concrete, asphalt and stone. Over the weekend South West Water were called out to the public toilets on Gyllyngvase Beach after reports of raw sewage spilling onto the beach. A manhole had lifted up and raw sewage had spilled onto the pavement. They conducted a CCTV survey and found the pipe had been blocked by a variety of building materials. It said it's next step would be to investigate and clear out the rubble. The area has been sealed off with red and white tape and cones on Monday.