Network Plus, a leading provider of utility and infrastructure services across the UK, has adopted SoilDri SEM as a core solution to enhance trench backfilling operations. This approach directly tackles one of the most persistent challenges within street works and utility installation: managing excavated soils that are too wet to be reused or compacted effectively.
In traditional trenching operations, high moisture content in clay and subsoil often renders excavated material unsuitable for reuse. As a result, contractors are required to remove this material from site, transport it to landfill or a tipping facility, and replace it with imported aggregates. This process not only increases project costs but also leads to excessive vehicle movements, programme delays, and additional environmental impact.
Network Plus recognised the inefficiencies of this approach and implemented SoilDri SEM to improve the condition of excavated soils directly on site. By reducing moisture content, the material becomes suitable for reuse within the trench, eliminating the need for waste disposal and significantly reducing reliance on imported aggregates such as Type 1 803.
The Challenge
Utility trench excavations, particularly for domestic water meter installations, frequently expose soils that cannot achieve adequate compaction due to high moisture levels. Under traditional methods, this results in:
- Removal and disposal of a significant proportion of excavated material
- Increased use of imported aggregate for surround and backfill layers
- Additional labour and time spent on material handling and logistics
- Higher transport costs, often requiring multiple trailer movements or grab lorries
- Risk of poor compaction due to segregated materials, leading to substandard ground conditions
Alongside these operational challenges, tightening environmental regulations are placing further pressure on contractors. With the phasing out of RPS 298 and 299 and the introduction of the Street Works UK Material Classification Protocol and WM3 requirements, landfill disposal is becoming more controlled and less commercially viable.
The Solution
By applying SoilDri SEM directly to excavated soils, Network Plus was able to transform previously unsuitable material into a stable, reusable resource. The product works by reducing moisture content without altering the soil’s fundamental structure, allowing it to meet the requirements for S4 Surround to Apparatus and S5 Backfill classifications under the Specification for the Reinstatement of Openings in Highways (SROH).
This non-binding solution enables consistent compaction and improved stiffness, addressing common issues associated with wet soils and segregated aggregates. As a result, crews can complete reinstatement works more efficiently and with greater confidence in the long-term performance of the trench.
Operational Benefits
The implementation of SoilDri SEM delivered immediate and measurable improvements across Network Plus operations:
- Reduced Costs: Eliminating landfill disposal and significantly reducing imported aggregate resulted in substantial cost savings.
- Lower Carbon Emissions: Fewer vehicle movements and reduced material importation contributed to a lower overall carbon footprint.
- Improved Efficiency: Crews spent less time managing materials and more time completing productive work, accelerating project delivery.
- Enhanced Health & Safety: Reduced manual handling, fewer vehicle movements, and shorter open excavation times lowered on-site risks.
- Minimised Disruption: Faster reinstatement reduced the impact on local communities and road users.
- Stronger ESG Performance: The solution supports sustainability targets by promoting material reuse and reducing waste.
In practical terms, the elimination of grab lorry usage alone delivered savings of approximately £1,000 per day. Imported aggregate usage was reduced by up to 80%, while landfill disposal costs were cut by up to 90%.
Quality Assurance
To verify performance, treated soils were tested using a Clegg Impact Soil Tester, a recognised industry method for assessing soil stiffness. Results showed a California Bearing Ratio (CBR) of 19% on the fourth drop, significantly exceeding the minimum requirement of 5%. This confirmed that the treated material not only met but surpassed performance expectations for load-bearing backfill.
Cost Comparison
The financial benefits were clear when comparing traditional methods with the SoilDri approach. A typical water meter excavation produces around one tonne of soil. Under conventional remove-and-replace methods, the combined cost of disposal and imported aggregate is approximately £30 per excavation. By contrast, using SoilDri SEM reduces this to around £8, representing a cost saving of approximately 73%.
Conclusion
By integrating SoilDri SEM into its operations, Network Plus has set a new benchmark for sustainable and efficient trench backfilling. The ability to reuse site-won materials eliminates waste, reduces costs, and ensures compliance with evolving regulations.
This case study demonstrates a clear shift in industry practice—moving away from disposal-led approaches towards smarter, more sustainable solutions. With benefits spanning cost, performance, safety, and environmental impact, SoilDri SEM provides a practical and compliant method for modern utility and street works projects.
