Second Sluice

The Witham Drainage Act 1762 among other things constituted the Commissioners of Sewers for the Second and Sixth District, which covered the area including Asgarby, Ewerby, Great Hale, Heckington, Holland Fen, Howell, Little Hale and South Kyme.^[1] Much of the area to the south and west of Boston, some 91 square miles (240 km²), was inundated by the Great Flood of 1763,^[4] and against this background, the Black Sluice Drainage Act 1765 (5 Geo. 3. c. 86) was obtained which created the Black Sluice Commissioners, giving them power to raise taxes and authority to carry out drainage works. The scheme largely revived the Earl of Lindsey's original scheme.^[1] The initial design work was carried out by the civil engineer Langley Edwards, on loan from the Witham Commissioners. Some of the surveying was performed by John Landen, who was the steward of the estate of Earl Fitzwilliam at Peterborough, and a proficient amateur mathematician. The two men were jointly appointed Surveyors of the Works, acting as engineers for the scheme, while John Chapman and Richard Strattard were assistants. A new sluice, called the Black Sluice, was built at Boston as a direct replacement for the Skirbeck Sluice, having three openings with a total width of 40 feet (12 m). The 8 miles (13 km) of the drain were scoured from Boston to Great Hale, beyond which the Main Drain was upgraded by cutting a new 14-mile (23 km) channel, effectively extending the South Forty-Foot Drain to Guthram, on the banks of the River Glen.^[4] A total of 65 miles (105 km) of highland streams were improved by scouring and raising of the banks. The estimated cost of £16,000 was raised by issuing bonds, but the project overran, and another Act of Parliament, the Black Sluice Drainage Act 1770 (10 Geo. 3. c. 41) was obtained in 1770 to authorise the raising of the drainage taxes, to cover the difference.^[1] By mid-1769, when Landen and Edwards left the project, because the work was largely complete, the scheme had cost £24,000. They were replaced by Edward Hare as Surveyor of Works, with Chapman and Strattard continuing as assistants. A historian called W. H. Wheeler, who chronicled the Lincolnshire fens, wrote that "the works were efficiently carried out and, being well-designed, entirely answered expectation."^[4]

On the River Witham, the Grand Sluice was constructed and opened on 15 October 1766, and this prevented tidal water from entering the river, and hence flooding the Holland Fen. The Boston Harbour Commissioners were created by the Boston Port Act 1766, and they carried out improvement works to The Haven, which resulted in lower water levels at the Black Sluice, and hence more efficient draining from the South Forty-Foot Drain. Water was pumped into the drain by a series of windmills driving scoop wheels. Maps of the area produced in 1783 by Edward Hare show 46 such mills, which provided drainage for 32,000 acres (130 km²) of agricultural land. Extreme high tides in 1810 and again in 1820 resulted in widespread flooding, and further thought was given to improving the flood defences.^[1]

With the improvements to the River Witham, the final section of Earl Fitzwilliam's drain to Lodewick Gowt was filled in, and the channel was diverted to join the South Forty-Foot Drain. Renamed the North Forty-Foot Drain, it now supplies Cook's Lock and Holland Fen pumping stations.^[3]

Third Sluice

Reports on improvements to the system were produced in 1843 by the surveyor Mr W Lewin and in 1845 by Sir John Rennie. Rennie's scheme involved the provision of a catchwater drain to collect water draining from the higher ground to the west before it entered the fenlands, but an Act of Parliament to authorise its construction was defeated, and so in 1846 a report by Mr W Cubit which proposed improvements to the existing infrastructure was accepted by the Commissioners. A new Black Sluice, including a 20-foot (6.1 m) wide navigation lock, was constructed to the south of the original one, with the cill level 6 feet (1.8 m) lower, which enabled the gradient of the South Forty-Foot Drain to be increased to 3 inches per mile (5 cm/km). Many of the tributary drains were also improved. 1846 also marked the beginning of the use of steam engines for pumping. Ten years later, a map covering 18,000 acres (73 km²) of the Black Sluice area showed nine steam-powered and eight wind-powered drainage engines in use.^[1]

The River Witham Outfall Improvement Act 1880 (43 & 44 Vict. c. cliii) authorised further improvements to the mouth of the Witham, to which the Black Sluice Commissioners contributed £65,000. This work led to a further drop of 4 feet (1.2 m) in the low water level at the Black Sluice. Oil and paraffin engines began to replace steam and wind engines from 1910, and by 1935 there were 15 such engines pumping water into the South Forty-Foot Drain. The passing of the Land Drainage Act 1930 resulted in the Commissioners being replaced by the Black Sluice Internal Drainage Board,^[1] while responsibility for the rivers in the area passed to the Witham and Steeping Rivers Catchment Board.^[5] With war imminent, the Rivers Board took over the Black Sluice and the South Forty-Foot Drain in 1939, and although progress was interrupted by the Second World War, a £374,000 scheme to construct the Black Sluice pumping station and to widen 11 miles (18 km) of the drain from Boston to Donington Bridge was completed in 1946.^[1] The pumping station contained three 100-inch (2.5 m) pumps, each powered by a 900-horsepower (670 kW) 5-cylinder vertical diesel engine manufactured by Ruston.^[6]

Modern era

Paraffin and oil engines gave way to electrically powered pumping stations in the 1950s, with the Board constructing six electric and one diesel pumping station to improve drainage to an extra 11,000 acres (45 km²) of land. In 1960, the decision was taken to further improve drainage of an area of 70,000 acres (280 km²), as part of a £1.4 million scheme which included the addition of two extra pumps at the Black Sluice, replacement of existing pumps elsewhere, and the widening of 7 miles (11 km) of the South Forty-Foot Drain from Donington Bridge to Rippingale Running Dyke. Jurisdiction for the Drain and the sluice passed to the Lincolnshire River Board at this time. The work, which began in 1962 and was completed in 1968, proved successful in preventing flooding during severe wet weather in the winter of 1968/9.^[1] With three 900-horsepower (670 kW) and two 925-horsepower (690 kW) diesel engines, the upgraded pumping station could pump 800 thousand gallons per minute (60 m³/s). Responsibility for the drain and the sluice passed to the National Rivers Authority in 1990, and to the Environment Agency in 1995.^[7]

Despite all the improvements, serious flooding occurred in 1999 when the bank of the drain was breached near Pinchbeck. Staff from the Environment Agency and the Black Sluice Internal Drainage Board successfully repaired the breach before properties were flooded, and a review of the flood defences was then carried out. The report recommended improvements to some of the banks, but funding for the work was not available, and so no work was done at the time.^[8]

In 2013, the pumping station flooded as a result of a tidal surge. The three engines dating from 1946 were damaged by water ingress, and were decommissioned. The other two engines were at a higher level, and remained operational, but were by that time nearly 50 years old, and nearing the end of their operational life. Refurbishment of the pumping station was estimated to cost between £15 and £20 million, and so the effectiveness of the station was reviewed.^[9] The review showed that it had been used for less than 2 days of every 100 days since it was constructed in 1946, and that the station barely affected the number of properties that might be flooded. By using the adjacent gravity sluice and the lock to discharge water from the South Forty-Foot Drain, better control of water levels could be achieved, and this had been demonstrated during a period of heavy rainfall in spring 2018.^[10] Accordingly, the remaining two pumps were decommissioned in October 2018, and the Environment Agency are looking at what to do with the building.^[11]

Development

Phase 2 of the Fens Waterway project involves the link between Donington Bridge and Crowland and Cowbit Washes, which are located on the River Welland near Spalding. In order to make the financing of the phase more viable, it was split into two halves, with phase 2a covering the section from Donington to Surfleet Seas End on the River Glen, and phase 2b covering from there onwards.^[20] The initial technical assessment and obtaining of planning permission for phase 2, which involved widening of the South Forty-Foot Drain from Donington to a new road crossing under the A151, a new lock and a junction with the River Glen at Guthram Gowt was funded by the East Midlands Development Agency.^[25] This section would involve changes at Black Hole Drove pumping station, which has been built across the drain and hence would prevent navigation.^[17] Major contracts for this phase were expected to be awarded in April 2009,^[20] but appraisal of the technical assessment revealed that more than one route needed to be considered before the best solution could be selected. While the obvious solution would be to connect the Glen and the drain where they are only a short distance apart, the Lincolnshire Waterways Partnership also considered the creation of new channels up to 9.3 miles (15.0 km) long to form the link. In the meantime, the economic situation changed, so that sources of funding were not so freely available, and by the end of 2010, no clear dates had been set for the next construction phase.^[26]

By late 2011, there were ten different routes under consideration, and an assessment of them was expected to be delivered in spring 2012. Halcrow Group, the engineering consultancy, were responsible for carrying out the assessment, which looked at the benefits that each route might provide, not only for navigation but also for water quality, water resources and habitat for wildlife. The study was expected to provide a short-list of routes, which would then be the subject of further consultation.^[27] By mid-2012, the merits of the ten routes had been considered, including the economic, environmental and technical issues involved, and a broad outline of the corridor for the link was scheduled to be published in September. After that, consultation with landowners and stakeholders took place, to establish the final route, for which design of the channel and the associated locks, bridges, moorings and pumping stations could then begin.^[28] By the end of the assessment process for the ten routes, two remained. One was route 1, the original suggestion which used the existing course of the South Forty-Foot Drain for most of its length, while the second was a new route, designated as route 11. Route 11 had become the preferred route by the summer of 2014. It involves widening the South Forty-Foot Drain from Donington to Surfleet, to a point near to the Black Hole Drove pumping station. A new lock would be needed at this location, but would connect to a new channel, rather than to the rest of the drain. It would pass under a new bridge on the A151, and the connection to the River Glen would involve another new lock. An environmental survey of other watercourses near to the route revealed that several provide habitat for nationally important plants and invertebrates.^[29]

Precursors

The idea of a link between the South Forty-Foot Drain and the River Nene is not new, as the first plans for such a connection were proposed in 1809. In that year, proposals for a new canal between the Oakham Canal at Oakham and the Stamford Canal at Stamford, which had been discussed in 1785, were revived, as part of a larger plan for a 7-mile (11 km) link from Stamford to the River Nene at Peterborough, and a connection from near Market Deeping, where the Stamford Canal rejoined the River Welland, northwards to the South Forty-Foot Drain. A bill for this, together with one for a rival scheme to link Stamford to the Grand Junction Canal, which also included a connection to the South Forty-Foot Drain, were put before Parliament in 1811, but neither met with any success. The idea was raised again in 1815 and 1828, but no further action was taken.^[30]