The pumps in a large 16m wide and 20m deep inlet pumping station at a wastewater treatment works were frequently blocking due to the volume of silt and screenings in the wet well.
The thick layer of sludge, screenings and silt in the wet well was first removed using a DISAB vacuum tanker working from the top only. As the levels of sludge, screenings and silt in the tank decreased a safe working area was cleared in the tank. Once the tank was deemed to be safe to enter after gas testing, two confined space trained operators were lowered into the wet well using a man riding basket and mobile crane. A further mobile crane and man riding basket was on standby at all times. When the operators were safely on the base of the well, the remaining material was broken up using the JetVac’s jetting hose and removed using the DISAB’s vacuum hose. The material removed from the well was screened using the mobile Screening and Dewatering Plant and the screened water was pumped back into the site drainage. The silt and debris was deposited into an eight yard builders skip for disposal offsite using our skip vehicle.
