Pumping station may have spared Boston homes from flooding, drainage board says

The assertion has been made by the Black Sluice Drainage Board (BSIDB), an authority set up to control water levels and reduce the risk of flooding in and around Boston.

It also argues that if the Black Sluice Pumping Station had been in action, the amount of agricultural flooding could have been ‘significantly reduced’, not only earlier this week, but also in previous flooding events during the 2023/24 winter.

The Black Sluice Pumping Station, in London Road, was constructed in 1946 with three diesel pumps, followed by an additional two pumps in 1966. When operational, they were able to move 60 cubic metres of water per second.

However, the facility was decommissioned in 2018, following a study led by the Environment Agency (EA) that ran between 2012 and 2016.

The study aimed to understand the flood risk in the South Forty Foot system.

Ultimately, it was decided that the cost to refurbish the pumps outweighed the resultant benefit, with the study having found that the equipment did not play a significant role in managing flood risk.

The adjoining gravity sluice and dual-purpose lock would be the focus of funding and resource for the Environment Agency, instead.

Following flooding from the South Forty Foot Drain this week, the BSIDB has called for the decision to decommission the pumping station to be revisited.

In a statement signed by chief executive Daniel Withnall and chairman Paul Holmes, it said: “The Black Sluice Internal Drainage Board extends its heartfelt sympathy to the residents whose homes have been flooded and to the farmers whose fields have been affected by the recent flooding in Boston and the wider Black Sluice Catchment area.

“The Board firmly believes that had the pumps at the Black Sluice Pumping Station been fully operational, the flooding of homes in Boston last night may have been prevented, and the extent of agricultural flooding could have been significantly reduced, not only in this incident but also in previous flooding events during the winter of 2023/24.

“In addition to the direct flooding caused by the overtopping of the South Forty Foot Drain, we are also seeing secondary impacts from highland carriers, which overflow when they are unable to discharge into the South Forty Foot Drain. This includes flooding in villages such as Billingborough, Helpringham, Scredington, and other areas to the west of the drainage district.”

“The Board is committed to making representations to the Environment Agency, and wider government departments, that the 2013/14 flood modelling is revisited, taking into account the new data and experiences from these recent events,” the statement continued. “The original modelling indicated that decommissioning the Black Sluice Pumping Station would only have a limited impact, affecting a small area of agricultural land and around five properties, where individual flood prevention measures could be implemented. However, with 40 properties now flooded in Boston, including homes on the edge of a large housing estate, it is critical that this modelling be reassessed to better reflect the current situation.”

The statement concluded: “The Black Sluice Internal Drainage Board remains fully supportive of the Environment Agency and the vital work it does. We look forward to continuing our partnership with the agency to enhance flood protection for the residents and ratepayers within the Black Sluice Catchment.”

In response, a spokesman for the Environment Agency said: “This week we have seen record river levels in the South Forty Foot Drain and the surrounding catchment due to heavy rainfall, snowmelt and frozen ground increasing run-off.

“Black Sluice Pumping Station officially ceased operation in 2018, following a joint decision by partners including Black Sluice Internal Drainage Board, Lincolnshire County Council, Boston Borough Council and the NFU. This decision was based on a four-year modelling study, which showed that whilst the pumping station makes a small difference to flood risk, this reduction in risk could not outweigh the cost of refurbishing and running the asset for the future. In addition, current use of the navigation lock has been proven to discharge the same amount of water, if not more, from the South Forty Foot catchment than the pumping station can.

“In Billingborough, flooding occurred the day prior to flooding in Boston. Our evidence is very clear that the earlier flooding to villages in the upper catchment is unrelated to whether the pumping station in Boston was used.”

The Environment Agency added that, with its partners, it will be carrying out a review of current flooding impact to properties across the South Forty Foot catchment, to understand the source of flooding for all locations.

It described itself as ‘committed to managing flood risk’ in the South Forty Foot area, and said it will ‘continue to invest in the successful operation and resilience’ of lock and sluice, as well as other flood risk structures in the area.

During the current flooding incident, Environment Agency teams continue to be out on the ground operating flood defences, taking action to reduce the impact of flooding, and supporting those communities affected, it added.