River Idle - Drainage

Drainage

The banks of the river below Bawtry have been raised so that the river acts as a high level carrier for the drainage of the surrounding land. The area between the river and the Chesterfield Canal to the south and the Warping Drain to the north is drained by a network of drainage ditches, which are connected to the river by a number of sluices and pumping stations. Water is pumped from the ditches to avoid flooding of the agricultural land, although the pumping station at Gringley can operate in reverse, supplying water to the ditches for irrigation when required. The outflow into the River Trent is controlled by a pumping station and two sluices. A vertical sluice gate protects the entrance to the Idle, and the pumping station and another sluice are situated further back. When the water level in the Trent is low, the sluice gates allow water to leave the Idle by gravity, but at high tide, four electric pumps are used to pump the outflow into the space between the sluice gates until it can again discharge by gravity. The pumping station was commissioned in 1981, and was the largest all-electric pumping station in Britain at the time. When all four pumps are operating, it can discharge 2,124 tons per minute (3,059 Mld).

A large drainage ditch called the Mother Drain runs parallel to the lower river for the final 10 miles (16 km). This was constructed between 1796 and 1801 by the engineer Thomas Dyson, to collect water from the low-lying land to the south of the river. Vermuyden's single sluice was replaced by a triple sluice at this time. The Mother Drain was pumped into the river by two pumping stations at Misterton Soss, the first example of steam engines being used for land drainage outside of the Fens. The first station, called Kate, was built in 1828 and used a 40 horsepower (30 kW) beam engine to drive a 34-foot (10 m) scoop wheel. The wheel was replaced by a centrifugal pump in 1890, and the beam engine was replaced by a 135-horsepower (101 kW) twin cylinder steam engine in 1895. The second, called Ada, was built in 1839, and another 34-foot (10 m) scoop wheel was powered by a beam engine supplied by Booth & Co, who were based at Park Ironworks in Sheffield. Both became redundant in 1941, when the drainage system was re-organised to feed excess water to a new pumping station at Gringley, containing two Ruston diesel engines driving Gwynnes pumps. By 1910, there was a bridge at this point which included tide gates, similar to the V-gates of a lock, which were designed to shut as the level in the River Trent rose. Both the north and the south pumping station are Grade II* listed buildings, and the south building carries an inscribed stone stating "These works erected 1828, Francis Raynes, George Kelk, William Gauntley (Commissioners), Alfred Smith, Engineer". They have been saved from dereliction by being converted to residences, their function performed by the modern electric pumping station at Gringley, while the tide gates have been replaced by the vertical sluice at the entrance to the river.

The low-lying region to the south of the Mother Drain is managed by the Everton Internal Drainage Board, who maintain around 34 miles (55 km) of watercourses. The Board has been operating in its present form since 1945, but is the successor to a similar body established in 1796 during the reign of King George III. The watercourses are pumped to the river at Gringley and Scaftworth. The Gringley pumping station was fitted with new diesel pumps in the 1940s, and was upgraded again in 2005 when electric pumps and an automatic weedscreen cleaner were installed.

On the north side of the river, drainage is managed by the Finningley Internal Drainage Board, who are responsible for the maintenance of 24.7 miles (39.8 km) of drains and ditches, which feed surplus water to four pumping stations. Hunters Hill, which is just above Haxey Gate bridge, and Idle Stop pumping stations are situated on the banks of the Idle, while Austerfield pumping station is set further back on the Austerfield Drain. The fourth pumping station is at Langholme, on the northern edge of the IDB area, and feeds into the Warping Drain, which joins the River Trent at Owston Ferry.

Above Idle Stop, the river flows through an area where drainage is the responsibility of the Rivers Idle and Ryton Internal Drainage Board. The IDB was re-formed in 1987, its responsibilities having previously been performed by the Severn Trent Water Authority, and manages 53 miles (85 km) of watercourses. Those to the west of the Idle drain into the river by gravity at a number of locations, but the region to the east of the river and to the north of Retford drains to a single outfall at Wiseton, where a pumping station pumps the water into the river when river levels are too high for gravity flow.