Ammanford Flood Risk Management Scheme

Overview

We’re moving forward with a scheme in Ammanford to manage flood risk from the rivers Loughor, Marlas and Lash.

We predict that more than 250 properties in the town are currently at risk of floodingwith a 1% chance of this happening each year during an extreme flood event.

The effects of climate change see this number rise to more than 450 properties at risk of flooding.

The areas of the town most at risk are Bonllwyn, Aberlash Road, Tir-y-dail, Gwyn Fryn and Shands Road.

We have looked carefully at the issues, causes and possible solutions to flooding in Ammanford.

Our investigations have shown that the cause of flooding in Ammanford is complex, with flood water spilling into the town at several locations.

A combination of measures is needed to reduce the risk of flooding. We believe that the best option is to construct a series of flood defence embankments and walls in several areas in the town to contain flood water in the River Loughor, and installation of Property Level Protection (PLP) measures to some houses on Aberlash Road.

Here are details of our specific proposals for each area that we are seeking opinions on from the community.

Gwyn Fryn Estate, Coleg sir Gar, Cwmllwchwr Mill and Shands Road

Upstream and downstream of Dyffryn Bridge, in extreme flood events water flows out of bank causing flooding to adjacent properties. This flood risk will be decreased by construction of flood walls at the college, Gwyn Fryn Estate and Cwmllwchwr Mill and Shands Road industrial units.

Gwyn Fryn Estate

We propose to construct a concrete wall next to the River Loughor in Gwyn Fryn Estate, starting at Dyffryn Road and finishing near the river, curving around the houses to the north. The river footpath will remain unaffected. The wall height will vary between 0.5m and 1m and will be clad with brick to match the houses.

This option will require felling of the large trees (mostly Austrian Pines from the Ty Dyffryn Estate grounds) between the houses and the river in Gwyn Fryn Estate. We have looked carefully at alternative options that could retain the trees, but because the space between the houses and the river is so restricted and the tree roots extend over a large area, there is no other feasible option that won’t cause damage to the roots or the trees.

We're proposing tree planting to compensate for the loss of the large trees and improve the landscape in Gwyn Fryn Estate. The replacement trees chosen will provide improved habitat and food for wildlife.

The native trees and vegetation on the riverbank will mostly be retained, as will the Austrian Pines to the north of the houses.

We are also proposing adding features for the community such as benches, garden hedges and other landscape improvements.

Shands Road

The industrial units on Shands Road are built on land that is more low-lying than the surrounding area. The preferred option here is to build a flood defence wall between the council-owned industrial units and the river.

The wall will be between 1.5m and 0.5m high and will connect to several of the industrial units to the north. These buildings will also be fitted with Property Level Protection measures to increase resilience to flooding.

The area behind the industrial units will be planted with trees to improve the landscape, increase habitat for wildlife and to help mitigate for the loss of trees elsewhere on the scheme.

Coleg Sir Gar

In the grounds of Coleg Sir Gar, the flood wall will continue south of Dyffryn Road for 80 metres along the river bank, gradually reducing in height until it reaches ground level. We have been able to design the route of the wall so it avoids two large (Category A) trees – a beech tree by the road and a large oak tree in the grounds. We are also looking to plant an area near the road with native trees and vegetation to increase wildlife habitat.

Cwmllwchwr Mill

On the opposite side to the college at Cwmllwchwr Mill, a flood wall and ground raising will be constructed between the industrial units and the river. This wall will continue south and link up with improvements we are making to the weir in the river channel. These improvements will decrease flood risk and also allow fish to pass over the weir for the first time since it was constructed. This will open up the river to the north for fish, giving them access to 20km of habitat for spawning.

Tir y Dail Field Bund

In an extreme flood, when the River Loughor overtops its banks in this field, water could flow down the field and along the railway line. This could cause flooding to properties on Shands Road, Station Road and Harold Street. We propose to construct a large earth embankment across the field between Shands Road and the railway line to stop this flow path.

The bund will be around 130m long and will have a maximum height of 2.5m at Shands Road, sloping gently down to ground level in the field. The bund will be set back from the river so that the field continues to act as a floodplain during a flood. It has been designed to blend into the landscape as much as possible.

A small number of trees will need to be removed to enable construction of the bund, but we will plant new trees across the project site so that there is an overall increase in the number of trees on completion of the project. 

Ffordd yr Avon, Bonllwyn

We propose to construct a low flood defence wall along the south bank of the River Loughor in the Bonllwyn area, off Ffordd yr Afon. This will be around 90cm high, running on the river side of the existing footpath.

There is also gravel accumulating under the Llandybie Road bridge that will restrict flow under the bridge in an extreme event. We are looking at measures to prevent gravel building up and to ensure the free flow of water.

A vehicle ramp will be built down to the river at this bridge for future maintenance.

Some trees along the river will need to be felled to enable construction, but we will plant new trees in this area and elsewhere in Ammanford to compensate for any trees removed.

Parc Henry Lane

At the top of Parc Henry Lane, behind the new housing development, we propose to construct a bund to reduce the risk of flooding to properties around Llwyn-Y-Bryn.

In extreme floods, water comes out of the river above the new housing development and flows through the estate, causing flooding to properties.

The ground raising we propose will block this flood route and reduce the risk of flooding.

Aberlash Road

Some properties on Aberlash Road have a 20% chance of flooding each year.

We looked at increasing the opening under the Aberlash Road bridge to increase the amount of water that can flow under it and reduce flooding to properties. Although water depths were reduced, the frequency of flooding was not.

Options to store flood water upstream of Aberlash Road and to construct bunds to protect houses were also considered. However, these options were not viable due to a lack of available space and because the floodwater bypassed the defences. 

Property Level Protection (PLP) was identified as the most suitable option to reduce the flood risk for 13 houses on Aberlash Road, increasing resilience during flooding. PLP measures can include the fitting of “flood doors”, demountable barriers and similar products which form a temporary barrier to floodwaters in short duration flood events.

We completed surveys of the houses in March 2020 to ensure they are suitable for PLP. We will source suitable PLP products to install during construction of the flood scheme, for the property owners that agree to have them.

Potential environmental impacts and how we will manage them

An Environmental Impact Assessment (EIA) has been integrated into development of the scheme design. The EIA provides a systematic and transparent way of managing the environmental risks. It ensures that we avoid, reduce or mitigate environmental impacts and identifies opportunities for delivery of multiple benefits. Potential impact upon trees, protected species (e.g. bats, otter), people (e.g. noise), historic features, local landscape are some of the many impacts that have been assessed. An Environmental Constraints and Opportunities Record has been produced to document the EIA, which will be made available to the public and key stakeholders for consideration as part of the Planning Consent Pre-Application Consultation.

Environmental enhancements

Under the Environment Act and the Well-being of Future Generations (Wales) Act, NRW is required to pursue the Sustainable Management of Natural Resources (SMNR) and to demonstrate the application of the principles of SMNR and Sustainable Development (SD). Part of this will be achieved by delivering environmental and well-being enhancements in the Ammanford area, around the River Loughor catchment.

The enhancements that we will deliver as part of the scheme include:

• Improvements to fish passage over the Tir y Dail weir at Dyffryn Bridge, opening up 20km of habitat to fish such as Salmon, Sea Trout, Brown Trout, Eels, Lamprey
• Working in partnership with Carmarthenshire Council to deliver native woodland planting with public access (this is additional to the planting required to replace trees felled as part of the scheme)
• Habitat enhancements for species such as otters, birds and bats, including bat and bird boxes along the river
• Improvements to garden boundaries and seating in Gwyn Fryn Estate
• Information boards to provide the community and visitors with information about local features that may otherwise remain hidden – e.g Tir y Dail motte and bailey castle
• Treatment of non-native invasive plant species such as Japanese Knotweed

For details and images of each individual proposal, please see the newsletter below.

Why your views matter

Our preferred scheme will reduce the risk of flooding to approximately 380 properties in Ammanford during an extreme flood event (a flood with a 1% probability of happening each year), taking into consideration the impacts of future climate change.

This is your opportunity to comment directly to us on our proposals.

You will also have another opportunity to comment during the Planning Consent Pre-Application Consultation, before we submit the planning application to Carmarthenshire Council.

A draft copy of the planning application, including the Environmental Constraints and Opportunities Record, will be made available online on the project webpage.

The pre-application consultation will start in mid-January 2021 and will run for 28 days.

What happens next

Your feedback will help us shape our final proposals before we submit our planning application to Carmarthenshire County Council.

If you have said you would like to be kept informed of this project, we will be in touch either via email or post with feedback on this survey and our next steps.