Overview 

Mainmark UK was contracted to strengthen an 80-metre seawall where subsoil erosion caused by tides had led to voids forming behind. The project took place in a highly sensitive area, designated as a Site of Special Scientific Interest (SSSI), with additional environmental restrictions due to its designation as a Ramsar site for its importance to wintering birds. This meant that the project had to be completed quietly, efficiently, and within a limited timeframe to minimise disturbance to the wildlife and surrounding environment. 

Problem

The erosion of subsoil behind the seawall, caused by tidal forces, was threatening the structural integrity of the wall. The client needed a solution that would reinforce the ground behind the wall without disrupting the environmentally sensitive area or causing further damage. There were strict restrictions on when the work could be undertaken, with the team limited to working on the project between April and September to avoid disrupting the bird populations. 

Additionally, the solution had to be non-intrusive, to minimise the environmental impact. A product was required that could withstand tidal conditions and one that could be quietly implemented due to the decibel limitations imposed by the license.

Solution 

Mainmark UK proposed using its Teretek® resin injection technology, an ideal method for non-intrusive void filling and ground improvement. The resin was injected behind the seawall to reinforce the ground behind the structure, filling the voids caused by tidal erosion and strengthening the ground. 

Key steps included: 

1. Preliminary soil testing: before commencing work, Mainmark’s team conducted a series of tests to assess the suitability of the subsoil and clay. This helped to determine the required strength of the resin and the depth of voids that needed filling. 

2. Specialised product selection: given the seawall’s exposure to tidal forces, careful attention was paid to selecting a polymer that could withstand prolonged water exposure. Mainmark worked with the client to agree on a product tailored for the long-term durability of the structure. 

3. Resin injection process: the Teretek® resin was injected at key points behind the seawall to fill the voids and strengthen the ground behind the foundation. The process was executed within the permitted environmental restrictions, ensuring minimal disruption to both the wildlife and the surrounding area. 

Challenges 

The project presented several unique challenges:

• Environmental restrictions: the site’s designation as an SSSI and Ramsar site meant that strict environmental restrictions were in place. The work could only be carried out during a six month period, and the machinery used had to operate below a specific decibel level to avoid disturbing the wildlife. 

• Tidal constraints: the installation had to be carefully coordinated around the tides, as the seawall was subject to tidal coverage. This meant that there was a small window of time in which the work could be carried out, requiring precision and efficiency to ensure that the resin was injected at the right time. 

• Access limitations: the physical distance from the driveway of the building to the seawall was significant, requiring careful planning to ensure that all equipment, including the resin truck, had sufficient reach to complete the installation. 

Results 

Mainmark’s resin injection successfully strengthened the ground behind the seawall, filling the voids caused by tidal erosion and reinforcing the ground behind the structure. The project was completed within the limited timeframe, adhering to environmental restrictions and with minimal disruption to the site’s wildlife. 

By using the Teretek® resin injection, the need for traditional, more invasive, time-consuming methods was avoided. The quiet, non-intrusive nature of the resin application ensured compliance with noise restrictions, and the seawall’s integrity was reinforced in a timely and efficient manner. 

Client Testimonial 

The client was highly satisfied with Mainmark’s work, particularly the team’s ability to work within the strict environmental and tidal constraints.

According to the project’s site manager: 

“The team at Mainmark have been excellent. Communication and professionalism were outstanding from the planning stage to execution. They delivered exactly what we needed, within the tight timeframe and restrictions we had. I’d highly recommend Mainmark for future seawall and restoration projects.” 

The project has not only secured the seawall but also protected a valuable asset for the property owners, ensuring long-term asset preservation.

Conclusion 

Mainmark UK’s non-intrusive resin injection solution proved ideal for the strengthening  of the ground behind the seawall in this environmentally sensitive area. By delivering a targeted, effective solution within the stringent environmental and operational constraints, Mainmark showcased its expertise in ground improvement and structural strengthening, particularly in challenging coastal environments. 

Solutions: 

• Ground improvement

• Void filling

For more information on how Mainmark can help improve ground and protect critical infrastructure, visit Mainmark UK.