Retford Information Page

Overview

Retford Beck Information Page

Geography of area

Retford sits in the low-lying River Idle valley, where the Idle flows through the town from south to north. Retford Beck is a tributary of the Idle and arises in the high ground to the east of Retford. Both the River Idle and the Retford Beck are designated Main River. 

Annotated Aerial view of the lower Retford Beck catchment. Arup (2021). 

East of Retford, the Retford Beck has of two separate open channels. Each flow through farmland before entering the eastern outskirts of Retford at Grove Lane and Blackstope Lane. Each tributary flows in separate culverts beneath the Sheffield to Lincoln railway, followed by a short length of open channel. Flowing parallel to Grove and Blackstope Lane each respective channel re-enters culverts before combining upstream of the Chesterfield Canal, where the watercourse passes beneath the canal in a syphon. The Retford Beck remains in culvert beneath the town centre until it discharges into the River Idle. 

Recent Flood History  

Flooding from the Retford Beck is the main flood risk to properties upstream of the Chesterfield Canal, around the Blackstope Lane and Grove Lane areas of Retford. In recent years the area has been impacted by flooding with events occurring in 2000, 2007, 2012, 2015, 2018 and 2019. Internal flooding to properties was not reported in the 2012, 2015 and 2018 however 

In July 2007, 100 properties were flooded in Retford from both the Retford Beck and the River Idle. The majority of properties were in the Blackstope Lane and Grove Lane area. The main cause was very intensive localised rainfall, causing surface water flooding and raised the levels on the Retford Beck beyond the bank-full level. 

The lower River Trent catchment experienced intense and persistent rainfall, with over a month’s rain falling in 48 hours. The Idle and Ryton catchments had particularly heavy rain, with nearly two months rain falling in just 15 hours. 

29 properties suffered from interior flooding during the most recent event on 12th November 2019. Over 110% of the monthly total rainfall expected for November fell over 2 days after weeks of wet weather saturating the catchment. 

Aerial photograph of the November 2019 flooding, view towards the west. EA 2019 

As a Category 1 responder the Environment Agency have structured incident management, with duty staff available 24/7. Weather and environmental conditions are constantly monitored to support the preparedness of response and prioritisation of the most high risk communities.

During flood events the Environment Agency Field Teams carry out over-pumping of the Retford Beck as part of the coordinated response with resilience partners. Pumping improves the flow rate through the culverts and reduces flood levels to the Grove Lane and Blackstope Lane area. 

Environment Agency over-pumping on Grove Land during the 2012 flood event. (EA 2012) 

An initial assessment and Business Case for an upstream flood storage reservoir was developed by Bassetlaw District Council in 2018 and passed over to the Environment Agency in late 2019. The Environment Agency then continued to attempt a viable flood storage reservoir scheme for the Retford Beck.  

At the flood risk information event held in November of last year (2022) at Retford Town Hall, Environment Agency staff shared that the reservoir scheme was becoming difficult to progress due to an increase in the overall costs. All Environment Agency schemes must follow the Treasury Green Book rules for investment, where an evaluation of cost against economic benefit is mandatory during the appraisal process.  

Reservoirs are major projects and are complex to design due to the initial construction impacts, ongoing maintenance, and safety requirements. The concept design for the Retford Beck also interacts with site constraints increasing the design requirements:  

• The proposed reservoir would also be classified as Category A “High Risk” under the Reservoirs Act (1975) due to the proximity of the Reservoir spillway to homes downstream. 

• Existing utilities (gas & electric) cross the site and would have to pass under the embankment through the cut-off wall. 

• The farmland to the east of Retford contains ridge and furrow systems, and this historic landscape could be lost post construction. 

• Close proximity working with the Sheffield to Lincoln railway. 

• In November 2021 the Environment Act was enacted and introduced long-term targets to reduce the decline of wildlife, with legally binding targets to increase biodiversity net gain. At the time the Scheme planning application would be out for consultation, the legal requirement to deliver 10% biodiversity net gain is to be introduced. Due to the low-lying topography of the Idle Valley at Retford, the proposed reservoir would require 1.4km of embankments, where the alignment would require the removal of a significant amount of existing hedgerow and trees  

Since the public event last November, the economic assessment of the Retford Beck Flood Alleviation Scheme was updated and unfortunately, due to rising cost estimates, the total project cost outweighed the economic benefit of the proposed reservoir and made the scheme unviable. 

EA and partner future work

Following the decision to no longer proceed with the reservoir Scheme, the Environment Agency and Partners have changed their focus and other works are being undertaken to manage flood risk from the Retford Beck. 

Retford Beck Culvert renewal and replacement - The existing Retford Beck culverts beneath Blackstope Lane and Grove Lane are in poor condition and required repair. Ahead of commissioning this work, fluvial modelling is being completed to understand the positive or negative (if any) change in flood risk the potential works may create. Intrusive investigation work will be undertaken during this summer, and we are targeting construction to start in 2024. 

Retford Beck Catchment Natural Flood Management - Natural Flood Management is the use of small-scale interventions to "slow the flow" in the upper catchment that reduce flood flows downstream. Nottinghamshire County Council and the Trent Rivers Trust have already implemented Natural Flood Management measures at the Top Lodge Plantation in the Retford Beck catchment. The Environment Agency are going to work with them to further explore what measures are possible throughout the catchment. 

Flood Warning Service -The Environment Agency are developing a Flood Warning Service for properties affected by the Retford Beck. This service will provide advanced warning when flooding is possible. The Flood Warning Service will use weather forecasts and live river level monitoring to trigger alerts and warnings. A new gauge is being installed this summer to Retford Beck North, and we expect the service to be ready by the end of 2024. 

Operational response improvements - The Environment Agency Asset Performance team completed improvements to the Grove Lane debris screen and constructed a new concrete pad for reactive pumping. The new arrangements will improve the response time during flood incidents. A programme to exercise staff with the new pumping arrangements is in place. 

New Debris Screen and pump footing within the playing fields off Grove Lane. (EA, 2023)