Storm Christoph tests flood alleviation measures
Last month, Storm Christoph passed through the county and saw the County Council and its partners working together to prepare for and respond to the impacts of the storm.
A multi-agency response was co-ordinated to prepare communities for potential flooding and support and assistance was offered to residents, especially the clinically vulnerable.
Over 4,000 sandbags were deployed by VIA across the County and numberous roads were closed.
However, in Southwell, the storm gave assurance that the flood alleviation measures are working as designed, while further local drainage improvements to help the flow of surface water reach the drainage network continue to take shape
Works on Church Street, in the region of Commissioner’s Bridge, are due to be completed by the middle of February. This includes the installation of new gullies which will help water to flow into new pipes and discharge into the dyke. Modifications will also be made to the existing bridge parapet, which will help surface water flow into the dyke at times when the water level is high.
When these works are complete, focus will then turn to Lower Kirklington Road, near the bottom of the Rope Walk. Work will be carried out to improve the transport of surface water off the highway into the Dumble and away to the Greet rather than flooding the road or nearby properties.
The non-intrusive Ground-Penetration Radar (GPR) survey has now been undertaken at the Potwell Dyke site to establish if there are any further buried archaeological artefacts. The results will be used to help inform the design of the proposed flood water store which will then be shared with residents. Hopefully, subject to planning approval, work will be able to start in the Summer.
As spring approaches, landscaping works will be taking place along Southwell Trail. This will see the planting of four new large field maple trees to give immediate impact and over 40 more trees and shrubs comprising alder, hawthorn and willow in mixed groups
Latest updates on all the works in Southwell, along with some Frequently Asked Questions can now be found at www.nottinghamshire.gov.uk/southwellflooding
Southwell flooding works continue into 2021
2020 has seen works completed at Lowes Wong School, on Hopkiln Lane and along the Southwell Trail, and 2021 looks set to be another busy year for flooding works in Southwell.
Works on Church Street began on 12th January and will see the installation of new gullies and modifications to the existing bridge parapet.
These new gullies will help water to flow into new pipes and discharge into the dyke, which will minimise the risk of any potential flooding. As for works on the bridge parapet which is located on the bend of Church Street, the modifications will help surface water to flow into the dyke at times when the water level is high.
These works are part of an area wide improvement programme to help the flow of water from built-up areas enter the existing drainage system. Via East Midlands will also be progressing similar work at other locations in Southwell, including Crafts Way/Merryweather Close, Lower Kirklington Road, Monckton Road, Ropewalk and Easthorpe. Once the ongoing drainage surveys are complete the installation of new gullies, pipes and kerbs will be undertaken.
Elsewhere in Southwell, the design team from Via East Midlands is working on plans for the creation of a flood water store adjacent to the Potwell Dyke which would temporarily store flood water during times of extreme rainfall to protect nearby properties.
You may have heard that buried archaeology has been discovered on the site, and due to this, a non-intrusive Ground-Penetration Radar (GPR) survey will be carried out to determine the exact location and extent of the archaeology.
This survey is key to determine if the detailed design process to can go ahead and to ensure that impacts on the site can be minimised, once complete, any scheme that is proposed will then be subject to planning approval.
One of the successes of 2020 was the completion of works along the Southwell Trail, which is now open for public use. Between January and March, landscaping works will be taking place along the trail to coincide with planting season.
Did you know that rivers, brooks, streams, culverts and roadside ditches are all watercourses even if they don’t contain water all year round? Watercourses help manage surface water, prevent flooding and improve habitats for wildlife so it’s important to keep them clear and well maintained.
If you have a river, brook, stream, culvert or roadside ditch running through, underneath or next to your property it’s your responsibility to look after them. You will often hear this referred to as Riparian Ownership, and as the lead local flood authority, the county council will work with riparian owners wherever possible to make sure regular maintenance takes place and to help facilitate the work. As a riparian owner you must:
Keep structures that you own, such as culverts and trash screen weirs, clear from debris
Maintain the bed and banks of the watercourse, including shrubs and trees
Clear away debris, even if it did not originate from your land
Allow water to run through your section of the watercourse without any obstruction, pollution or diversion
- Not impact the rights of your downstream neighbour which in turn means that you will not be impacted by your upstream neighbour
For more information on the project, please visit: www.nottinghamshire.gov.uk/southwellflooding
Local drainage improvements
As the calendar year draws to an end the team at Nottinghamshire County Council and Via would like to send everyone good wishes for the festive season and the year ahead! The update for December looks at the schemes that are in addition to the larger scale projects, within the Southwell Flood Alleviation work.
The project team at Via East Midlands is busy progressing more localised, largely highways-based improvements to specific areas of Southwell. The objective of these smaller scale schemes is to help rainwater falling within the built-up areas of the town move to the existing drainage so that water can be transported away rather than flowing over land and causing flooding of residential and business properties. The areas of focus have been identified through hydraulic modelling which has taken into account the positive impact of the larger scale schemes that are already implemented and designed. Locations under review include:
Highway drainage improvements along Church Street with better connectivity into Potwell. A ground penetrating radar survey will be taking place shortly to help investigations around the Potwell area
Better connectivity and transport Crafts Way / Merryweather Close
Better surface water drainage and highways drainage connectivity along Lower Kirklington Road
Measures to reduce surface water flow into Monckton Road
Measures to maintain and improve flow within the Ropewalk
Measures to improve transport of surface water from Easthorpe and areas downstream towards the Greet
The trail is open for public use and the landscaping works are programmed for the planting season; November 2020 – March 2021.
Latest updates on all the works in Southwell, along with some Frequentl
Works complete on Hopkiln Lane
The Southwell Flood Risk Management Project is not just about larger schemes like the works at Lowes Wong School and along the Southwell Trail.
You may not know that there are a number of smaller scale highways drainage schemes being developed across Southwell to provide further protection from flooding.
If you have seen works taking place on Hopkiln Lane, then you have seen one of these area surface wide schemes taking shape.
Works began on Hopkiln Lane in September to improve the flow of surface water into the drainage system and away from nearby housing.
The design of this scheme features new highways gullies which will collect the flow of water into the drainage system. They will work alongside newly installed kerbs which will act as a barrier to water flowing towards nearby houses.
The drainage system itself has also undergone improvement works including the replacement of the existing culvert underneath the road with a new one.
This will improve the flow of water into the watercourse once collected by the new gullies, and as the pictures show, the banks leading down to the culvert will also direct water into the drainage system to prevent surface water flowing into houses.
Works on Hopkiln Lane were completed at the end of September and the focus on the area surface wide schemes will now turn to Church Street where proposals are being developed to ensure surface water can run-off more effectively.
The past month has also seen recognition from the Institution of Civil Engineers East Midlands Merit Awards 2020 for the Property Flood Resilience works undertaken in Southwell.
Nottinghamshire County Council’s Flood Risk Management Team has been awarded the ‘Highly Commended’ award in the small project category for the works, which to-date have seen over 100 properties in Southwell protected from flooding using bespoke measures.
The project was delivered by Whitehouse Construction Ltd and was applauded for its team approach and liaison with the community affected.
To find out more about the Southwell Flood Risk Management Project, visit: https://www.nottinghamshire.gov.uk/planning-and-environment/flooding-help-and-advice/southwell-flood-risk-management-project
Works complete at Lowes Wong as works begin in Hopkiln Lane
A permanent pond with a pond dipping boardwalk, a sunken wet orchard and raised bed rain gardens will benefit the learning of children at Lowes Wong School in Southwell, as well as the site itself.
Despite heavy rainfall last Autumn and the impacts of the COVID-19 pandemic, main works on the sustainable urban drainage system at Lowes Wong School are now complete.
Work began in August 2019 to reduce the volume and speed of surface water flow during periods of heavy rainfall, by increasing both the capacity of water storage on-site and the potential for water to seep back into the ground at a slow rate.
Early investigations showed that just 20% of rainfall on the school grounds was discharging directly off the site, and that the sloped landscape and clay ground surface meant that the remaining water could flow quickly towards on-site drainage systems before overwhelming them.
One of the main challenges faced by the design team from Via East Midlands was safely capturing and retaining volumes of water on an active school site, but what has followed is as beneficial to pupils as it is to reducing future flooding on site.
While swales, bunds, detention basins, ponds, water orchards and raised rain gardens have all been carefully designed to slow water flow and increase storage, they will also support the learning of primary and junior children and the school’s gardening club.
The project is now being monitored and newly sown grass sward across the site will stabilise the ground into active surfaces. The design team will be in close contact with the school and while the soft engineered design of the project means minimal maintenance will be needed, the team will be on-hand in coming weeks to monitor any impacts on site.
Meanwhile, works on the Southwell Flood Alleviation Scheme have now moved on from the Southwell Trail towards Hopkiln Lane.
These works will ultimately improve the passage of surface water away from housing and into the nearby watercourse and will see the replacement of an existing culvert which runs underneath Hopkiln Lane.
These works have required Hopkiln Lane to be closed, and a diversion is in place, however residents and motorists can be assured that works are progressing and therefore, contractors hope to have the road open by the end of September.
We would like to thank residents in Southwell for their continued patience and understanding while we carry out works across the town.
More information on the Southwell Flood Alleviation Scheme can be found at: www.nottinghamshire.gov.uk/southwellflooding
Trail works recommence following lockdown
In March, works on the Southwell Trail had just begun, and over the next few months, site clearance, removal of vegetation and the reprofiling of the existing ditch were scheduled to get underway.
Unfortunately, March also saw the beginning of the COVID-19 lockdown. Works on site in Southwell were paused, office-based staff were relocated to work from home, and site visits for design and survey purposes were unable to go ahead.
Fast forward to 8 June and works officially got back underway on the Southwell Trail. Despite the challenges of COVID-19, Via East Midlands and Nottinghamshire County Council worked closely to make sure that staff could return safely and in line with government guidelines.
Works on the trail will ultimately improve the passage of water away from homes and once complete, the trail will be able to store an increased amount of flood water before it is released into the River Greet.
You may have seen the works taking place on site, and to date, site clearance has commenced, including the visible removal of overgrown vegetation.
An ecologist from Via East Midlands has joined the design team to oversee the conservation and protection of wildlife as the works continue, and as the site is cleared, there is a particular focus on avoiding impacting nesting birds along the trail.
The key component of the works along the Southwell Trail is a reprofiled ditch which will be lined with concrete canvas to ensure its capacity will not be reduced by weeds and silt deposits.
The ditch at the rear of the properties will hold water, which will then be able to flow out at Station Road, the field at the rear of the industrial estate or the Dumble.
The connection from the ditch at the rear of the properties to the River Greet has been improved by the installation of two pipes that run across the field at the rear of the industrial estate. Non-return flap valves are to be installed on the end of these pipes at the River Greet.
It has been a successful few months on site and works on the trail are due to be complete in September. As autumn nears, works on Hopkiln Lane will begin, and more information about this will be included in next month’s update.
Latest updates on all the work in Southwell along with some Frequently Asked Questions can now be found at www.nottinghamshire.gov.uk/southwellflooding