Lodge Burn Flood Alleviation Scheme

76.4%

Whole Project Award

Project Team
Client: DARD Rivers Agency
Designers: Atkins
Constructor: McLaughlin & Harvey Ltd

Waste and material use Given the historic urbanised settlement in Coleraine Town Centre, it was expected that we would encounter contaminated land or waste arisings during construction. The team spent a lot of time specifying and performing site investigation across the site to determine the risk of contaminated soils and appropriate methods for management / treatment. It turned out that only one very small area of the site contained hazardous material which had to be removed to an appropriate disposal site, the rest of the material was retained on site for reuse. To ensure suitability for reuse, the team screened subsoils and removed inert contaminants (bricks, plastics, concrete etc). 800m3 of subsoil was processed of which only 40m3 had to be disposed. Of the total 2700m3 of material excavated for the culvert works 2160m3 was reused. This equates to 80% of site won materials. Incorporating recovery and off-site recycling, the Contractor diverted 95% of site wastes from landfill.

Land use and landscape

The Client and Designer identified early in the scheme development that there were significant opportunities to improve the river corridor and the use of lands adjacent to the watercourse. The flood defence scheme by default protects lands from flooding thereby improving their capability; however, the team wanted to take this further and improve amenity along the Burn for the local residents.

The landscaping and visual impact of the scheme was considered from commencement of the design phase. The flood walls finish was the most critical of all visual impacts on the scheme. The team agreed a patterned concrete stone-effect finish in keeping with the surroundings. Local hand dressed stone was used to clad the concrete parapet walls for entirely visual reasons.

The restoration of the river channel in Anderson Park provided the local Council with additional usable lands adjacent to the river.

Planting was performed across the site with a range of intentions – screening, ornamental, and water. A landscape architect was employed to advise the suitable plants and mix of planting at each location based on the requirements. The Designer specified pre-planted coir rolls, with native seed mix, for instant vegetation in the restored river channel.

Ecology & biodiversity

The existing river channel at the Lodge Burn was in poor condition with poor quality habitat and barriers to fish passage at Anderson Park and Railway Road culvert. It was a significant goal of the team to improve fish passage, habitat and water quality in the urban reach of the Burn. Consultations with NIEA, Fisheries Conservancy Board, DCAL Inland Fisheries, River Restoration Centre and RSPB were undertaken and recommendations made by these bodies incorporated into the overall scheme.

A particularly challenging aspect of the works was the need to perform all works on-line and 'in the dry' - this is no easy feat in a heavily confined urban watercourse. The team bypassed flows using gravity pipes which had minimal impact on aquatic wildlife - in fact we found some fish even using them to travel upstream across previous barriers to passage.

Additional habitat was created by restoring the river channel through Anderson Park and removing the poor quality pond area and weirs. The restored channel contains reed / aquatic flower planting and rock and cobble bed for spawning and resting areas for fish and to aerate the water. This area is to encourage upstream migration of Atlantic Salmon, Brown Trout and Sea Lamprey.

A key component added to the scheme as a result of early consultations was a fish pass. The fisheries bodies and River Restoration Centre provided significant advice and input to the preferred design of the fish pass. A rock pool and weir fish pass was selected due to its more natural finish and the ability to reuse stone and rock from the existing channel. There was no fish pass in the previous channel but the opportunity to improve fish passage could not be ignored.

Water quality improvements have been demonstrated globally on the Lodge Burn over the course of the works by an improvement from Bad WFD Status in advance of the works to a Moderate Status during the works.

Our neighbours

The Contractor registered the Lodge Burn project with the Considerate Constructors Scheme (CCS) and had two CCS audits over the course of the project. They obtained scores of 36/40 and 37/40 in the audits and were eligible for a national award.

The Contractor adopted a rotary cased piling technique at a particularly sensitive area to vibration in a further attempt to reduce vibration over the CFA piling technique selected at design stage. This was done in conjunction with underpinning of the last two properties in Mill Street to ensure the long term stability of the properties and prevent damage from vibration during the works. The construction programme also changed as a result of ongoing concerns over the stability of the Mill Street river bank and the need to secure the properties on Mill Street prior to commencing in the flood walls. The timing of the underpinning was determined in consultation with the owners and occupiers and the temporary closure of the units was planned to coincide with the quieter business period during the summer months.

The site fencing afforded local people the opportunity to observe the construction process and it proved to be popular among local residents to see the works progressing. The site staff received many questions and comments as a result.

Community relations

The construction works associated with the Lodge Burn project were within busy town centre areas heavily trafficked by pedestrians and vehicles. To ensure that the local community were well informed on what was going to happen in their area, the team invested significant time on advertising the scheme and keeping the public informed on scheduled works. This was achieved via a public open day, various leaflet / letter drops and the creation of a project website. The website contained all scheme details / drawings / visualisations, team contact numbers and weekly work ahead bulletins.

The Designer’s Community Liaison was the key point of contact for the project in the town and was well known around the town centre. She met with all affected landowners on a weekly basis to discuss progress and any needs to be addressed. She instructed the Contractor to perform mitigation / reinstatement works to comply with riparian agreements made with the affected landowners.

The Contractor continued to engage with the local community throughout the construction phase using newsletters, site signage with contact details and individual face-to-face meetings with landowners affected by the works to discuss mitigation of impact.

The design and reinstatement changed as a result of liaisons with local residents. These changes were captured in the individual riparian agreements drawn up with the affected residents. Examples of changes included additional landscaping or screening vegetation, improved paths / access to rear of properties and improved safety hand-railings.

The team identified opportunities to work with local schools to educate on river environment and used the Salmon in the Classroom activity as a means to get local children engaged in the river restoration of the Burn.

To what extent did the use of CEEQUAL influence your project?

The project team were very keen to use the Lodge Burn project as a means of showcasing that traditional flood defence works can easily incorporate environmental enhancement and river restoration elements.

The CEEQUAL process gave us a framework to develop our plans and work through to completion with the appropriate consideration and level of detail afforded to all aspects of sustainability and performance.

We were able to target specific areas within the assessment which we knew would make the most benefit to the project while using the project strategy set at commencement to guide our approach to all environmental matters.