Background
SA1 Swansea is located within Swansea City Centre, adjacent to the River Tawe, accessed from Kings Road. The 0.39ha site has a long and varied history, with a police station, Norwegian church and multiple factories all shown on historic maps. Most recently the site has been used as a car park. Planning permission was granted in 2018 for a multi-story student accommodation block with underground parking.
A Remediation Implementation and Verification Plan was produced for the site by ARUP following site investigation and monitoring. Asbestos fibres (<0.001% w/w) were identified within 9 / 33 samples, with arsenic, lead and PAHs also identified as exceeding the generic screening criteria for ‘Residential with Plant Uptake’ end-use. The site, centred in a prime location near Swansea Marina, was an exciting and potentially iconic development opportunity. Sanctus undertook both remediation and enabling works to release this site for much needed city centre development.
There were several technical challenges and opportunities to be addressed:
• The sites long and varied history left contamination, subsurface obstructions and potential UXO legacy issues.
• A number of complex contaminant hotspots required removal.
• The excavation of asbestos containing material was needed in a high-profile, highly visible city centre location, adjacent to occupied office buildings, a main road and public footpaths.
• The presence of highly sensitive environment receptors. The River Tawe runs parallel to the site along the entire western site boundary necessitating ongoing monitoring of groundwater.
• Regulatory liaison with Natural Resources Wales and the Local Authority.
• A safety-first approach was agreed, eliminating workforce exposure to contaminated Made Ground.
• The installation and geotechnical testing of a 620mm thick piling mat with high visibility marker geotextile and geo-grid.
• Sheet and CFA piling works required sensitive environmental monitoring to ensure noise and vibration levels did not create a public nuisance.
• The programme was extremely tight and paramount importance to the client due to the academic calendar.
Innovative Thinking and Exemplary Best Practice
Rather than reacting and implementing controls following the detection of asbestos, the health and safety of staff on-site and members of the public was proactively prioritised. A precautionary rather than reactionary approach was taken regarding asbestos exposure. As soil analysis covered only part of the site, asbestos controls remained in place for the duration of the works.
To provide reassurance to neighbouring properties and members of the public, near and far source air monitoring was undertaken throughout works.
The Sanctus approach to managing risk is built upon hiring great people and giving them the best tools for the job. All staff working on the project were trained and highly competent in working safely within this environment and with contaminated soils, including asbestos. One of our bespoke static decontamination unit was mobilised to site. The 40 yard unit, equipped with negative pressure system, is generously sized to allow for proper and thorough decontamination procedures. The unit acted as a single access point into and out of the controlled work areas again reinforcing the proactive approach to health, safety and wellbeing. Minimising dust was a key objective throughout on-site work, Sanctus therefore employed both oscillating point source suppression and a perimeter dust suppression system. Initial site investigation found a number of contamination hotspots harmful to human health.
Each hotspot had its limits defined, contamination excavated, and arisings placed on heavy gauge polythene sheeting to prevent vertical migration of any potential leachate. The impacted soils were subsequently disposed off-site at the nearest economically viable, suitably licensed facility, to reduce environment impact of transport. To ensure the hotspots were correctly and accurately defined representative soil samples were obtained from all four sides and the base of each excavation and analysed for the contaminants of concern. The removal of identified hotspots from site prevented pollutant linkages from becoming established and helped protect the surrounding environment and the River Tawe.
The Made Ground on-site was assessed as suitable for the site’s end-use as the material would be placed beneath hardstanding, or areas of landscaping, cutting all potential contaminant pathways. To protect future groundworkers / maintenance workers Sanctus pre-dug all drainage runs, pile cap locations and crane bases. The operation involved the replacement of contaminated Made Ground with quarried aggregate. A high visibility marker geo-textile was installed at the base of the aggregate to act as a visual marker, warning workers of the potential contamination below.
In this way, follow-on contractors benefited from our proactive approach to health, safety and wellbeing.
The close proximity of the River Tawe meant water course protection was of great importance. Four 6m deep sentinel boreholes were installed along the western site boundary. Groundwater physio-chemical parameters were monitored throughout the programme to ensure the enabling and remediation works had not altered the groundwater chemistry.
Environmental monitoring was undertaken on a daily basis across multiple Environmental Monitoring Stations (EMS), within and around the site. The Councils Pollution Officer was consulted on the location of the EMS’s and the specification of the noise monitoring equipment used.
The client’s and neighbour’s consideration were prioritised before, during and after project completion with noise, dust, litter and mud on public highways monitored and managed.
During sheet piling works three vibration monitors, recording vibration 24/7, were deployed around the north eastern and south eastern boundaries.
The implementation of the Sanctus culture especially around simple innovation and health, safety and wellbeing as demonstrated by the wide array of proactive measures and ongoing controls was pivotal to the hugely successful onsite operation.
Cost Effectiveness
The success of this project was defined by programme – the slightest delay in works would result in the planned academic intake being missed and catastrophic financial and reputational impact for the client.
To accelerate the CFA piling process, two piling rigs were employed at the site. To ensure both rigs were able to install the piles with minimal delays, Sanctus undertook extensive obstruction removal and detailed sequencing of work across the site. The location of each pile was pre-dug to the base of the Made Ground followed by specialist pile probing and UXO clearance operations. This accuracy and precision of our work enabled almost 99% of all piles to reach design depth without encountering any obstructions.
Throughout all works, data gathered on-site was uploaded to a shared cloud server daily for real time assurance. This proved to be a highly effective in saving cost, time and improving the user experience. Adopting cloud-based technologies onsite further demonstrates our commitment to continuous improvement and innovation.
Compliance with Legislation, Codes and Guidance
The presence of asbestos on-site necessitated strict adherence to Control of Asbestos Regulations (CAR 2012). Sanctus, as a licenced contractor, completed all asbestos works in accordance with these regulations.
For many projects, off-site disposal of material represents a significant proportion of costs and environment impact both in end point disposal and transport. Our commitment to quality and investment in high calibre operators and equipment means Sanctus can take a surgical approach to excavation minimise costs and environment impact. All materials disposed off-site were tested at a frequency of 250m3/sample, with all waste managed under the appropriate duty of care by licenced waste carriers to permitted disposal facilities.
To achieve the necessary bearing capacity to provide safe working conditions for the piling rigs, the client requested quarried aggregate to be imported to form a piling mat – this material was sourced from the closest economical viable supplier to minimise environmental and community impact. The mat was installed in four compacted layers with a geo-grid inclusion, aiding to distribute future loads. The imported material was subject to both chemical testing, to check it conformed to sites end-use, and geotechnical testing to ensure the CBR threshold had been met.
Public/Stakeholder Engagement
We take pride in our commitment to public engagement and inclusion and believe that our projects are ultimately designed to benefit people and the environment. This aspect of our culture is especially important in such a visible city centre location.
Following public consultation, working hours on-site were altered to suit the surrounding offices aligning with existing working patterns. The city centre road network was already heavily utilised and due to the location of the sites entrance, adjacent to a busy roundabout, there was limited space for vehicles to be parked on the road.
Sanctus therefore introduced staggered vehicle sequencing and successfully ensured vehicles operated within 10-minute windows throughout the programme of work to negate disruption to the local community.
Sanctus also supported a neighbouring optometrist agreeing that all works producing vibration would be halted during certain procedures. This further demonstrates the sensitivity with which Sanctus manage community engagement and inclusion.
Sanctus operate an open-door policy, with interested or concerned members of the public who are able to visit the site office and subsequently walked through operating procedures and environmental protection measures in place. Time lapse video footage was captured 24/7 throughout the project. This footage was shared with interested parties with a live feed streamed through the shared cloud server, allowing office-based staff 90 miles away to see live progress being made on-site and actively monitor performance.
Economic, Environmental and Social Benefit
The benefits of this project are numerous and far reaching. The site will be transformed from a utilitarian car park to modern, imaginative and inspiring accommodation for the next generation of students for the University and city. The intake of over 500 students every year will boost the local economy as an additional revenue stream is injected into the area. Developers have been encouraged to take on neighbouring brownfield plots, raising the profile of Swansea Harbour as a whole and contributing to the wider city regeneration.
The removal of contaminants from site has severed potential pollutant linkages that had the potential to impact the water quality of the River Tawe. With numerous species of fish, seabirds and occasionally seals and dolphins spotted in the Tawe during the site teams time in Swansea, it is clear wildlife is returning to this previously industrialised area.
With the regeneration of urban sites like SA1, the profile of Swansea City Centre and the surrounding area is beginning to grow and Sanctus are incredible proud to be part of Wales’ improving economic, social and environment future.
