Project Overview
A treatment plant located within an active industrial park required a new 110mm gravity drainage connection to discharge into an existing balancing pond. The proposed route crossed a heavily trafficked concrete yard used daily by commercial vehicles and plant machinery. Cutting and trenching the concrete was not viable due to the disruption it would cause, and the cost of reinstatement exceeded the cost of a trenchless solution.
Horizontal Directional Drilling (HDD) was selected to install the pipeline efficiently beneath the yard surface while keeping the site fully operational.
- Client: Industrial Site Operator
- Location: Industrial Park (UK)
- Duration: 1 day
- Method: Horizontal Directional Drilling (HDD)
- Length: ~66 meters
- Pipe Installed: 110mm MDPE SDR11 (gravity drainage)
- Ground Conditions: Mudrock and clay
- Outfall: Existing balancing pond (~6m below drainage outlet level)
Challenges & Solutions
High Traffic Concrete Yard:
The installation route passed beneath a concrete service yard with constant vehicle movement. Trenching would have required significant closure time and expensive reinstatement. HDD enabled a fully trenchless crossing, keeping operations running uninterrupted.
Steep Level Difference to Outfall:
The balancing pond inlet was approximately 6 meters lower than the existing drainage outfall, making grade accuracy critical to ensure consistent gravity flow. The bore profile was carefully planned and tracked to maintain a reliable fall to the discharge point.
Ground Conditions – Mudrock and Clay:
Mudrock layers and cohesive clay required controlled drilling to maintain bore stability. Drill tooling and fluid management were adjusted to achieve clean spoil removal and consistent progress.
Execution Strategy
Accurate Pilot Bore & Tracking:
A controlled pilot bore was completed with continuous locating to ensure the correct line and depth were maintained across the full 66m run.
Back Reaming for Pipe Installation:
The bore was enlarged appropriately to allow smooth installation of the 110mm pipe while maintaining bore integrity through variable ground conditions.
Single-Day Completion:
The pipe was pulled back and installed in one continuous operation, then terminated into the balancing pond infrastructure with a secure, professional finish.
Outcome
The new 110mm gravity drainage pipeline was installed successfully in just 1 day, without cutting or excavating the industrial yard slab. Site traffic remained operational throughout, avoiding delays, safety concerns, and high reinstatement costs. The new drainage route now provides a reliable discharge into the balancing pond, delivering long-term performance and improved site efficiency.
