Throckley, Filter Beds (Water Treatment Works)

An aqueduct was built from Whelton reservoir in Whittle Dean to Throckley Filter Beds in 1869. The water treatment works with extensive filter beds were completed in 1875 for the Newcastle and Gateshead Water Company. This involved extensive terracing and excavation of the area of the treatment plant, during the course of which the 'Walbottle Hoard' (SMR 1421) was found. The water treatment works were reconstructed in 1956. The filter beds have suffered from a degree of subsidence over the years. The valve houses (HER 1964 and 1965) are listed buildings {1}. Northumbrian Water has decommissioned the water works at Throckley and the site will be redeveloped in due course. Tyne and Wear Museums were appointed to record this industrial site. The water treatment works with extensive filter beds were completed in 1875 for the Newcastle and Gateshead Water Company, and linked to Whelton Reservoir in Whittle Dean by an aqueduct. The works were reconstructed in 1956. The two valve houses on either side of Hexham Road are listed grade 2. The northern valve house of 1870 stands within the waterworks site and is built of snecked sandstone with pecked quoins and dressings. It has a Welsh slate roof with overhanging eaves and a lead ball and spike finial. A sandstone block wall with semi-circular ashlar coping encloses the site and there are three sandstone gatepiers with chamfered edges next to Throckley Lodge. The naturally sloping site is retained by huge sandstone block revetment walls with red brick buttresses which allowed the site to be levelled some 3m above the height of Hexham Road. Arches in the base of the buttresses allow water to flow through a channel behind the wall. Above the sandstone wall is a five course red brick wall with ashlar coping stones. Inside the site are two tanks for aluminium sulphate, an administration building built in 1955, an electricity substation, two concrete filtration tanks, a settling tank with 24 courses of red brick and 12 courses of black-finished brick and chamfered concrete coping slabs and base. The filter beds are of similar construction, bordered by steel railings and with dividing walls forming catwalks. Water filtration removes colour from the water caused by peat or soil. The settling tanks allow the sludge to settle. The water is then filtered – originally through layers of sand and gravel, later through anthracite. Aluminium sulphate removes any remaining discolouration, lime maintains the alkalinity and chlorine the purity of the water, which was then pumped from the site by boaster pumps in the valve houses. A limited archaeological survey was undertaken in 2013 of the chamber below the north valve house.