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Stadium Pitch Ground Improvement

Challenge

A UK sports stadium built on a former industrial site suffered subsidence and voiding from corroded buried structures, threatening player safety, fixtures, and major financial losses.

Solution

Geobear injected geopolymers to 5.5 m depth, filling voids and stabilising soils while keeping the stadium operational — achieving zero fixture disruption and 75% lower carbon.

Zero

Match fixtures cancelled over 9 months

75%

Lower emissions than alternatives including excavation

5.5 metres

Depth of geopolymer injections into ground beneath pitch

Background

A major UK sports stadium, constructed within the last 20 years on a former industrial site, began to experience subsidence and voiding beneath the playing surface. The issue stemmed from the corrosion of buried tanks and pipes left from historic industrial use, leading to depressions forming across the pitch.

With visible settlement posing potential safety risks for players and the viability of matches, the stadium operator required an immediate solution that would avoid closure and protect revenue.

Challenge

The site presented multiple challenges requiring technical precision and programme flexibility:

  • Visible Depressions: Eight major depressions identified across the pitch, within tolerance but worsening. Further movement could have rendered the stadium unfit for play.

  • Historic Substructure: Legacy industrial features and redundant drainage lines contributed to unpredictable soil conditions and localised voids.

  • Groundwater & Washouts: Natural infiltration caused fine material migration, softening the underlying soils.

  • Operational Restrictions: Work had to be completed between scheduled matches, meaning short access windows and rapid demobilisation were essential.

  • Testing Adjustments: Standard testing methods proved inadequate, requiring a switch to CPT testing mid-project for more accurate strength verification.

Precision engineering beneath the pitch — Geobear kept the stadium open, safe, and sustainable with zero lost match days.

Solutions

Following detailed probing and geotechnical assessment, Geobear designed a targeted geopolymer injection programme that stabilised the soils without excavation or surface disruption.

Injection Design

  • Treatment Zones: Defined as high-intensity and medium-intensity based on soil condition mapping.

  • Depth: Injection tubes installed to depths of 4.5–5.5 m below pitch level.

  • Methodology: Controlled extraction technique used to deliver geopolymer resin at multiple levels.

  • Pitch Protection: Each injection point protected using Enkamat and purpose-built plyboards to prevent surface damage.

Execution

  • Injections were performed through small-diameter access holes across the affected areas.

  • The expansive geopolymer compacted soils, filled voids, and restored uniform bearing strength beneath the pitch.

  • Real-time monitoring ensured material expansion remained within design tolerances, avoiding any surface heave.

Delivery Constraints

  • Hard soil layers encountered during drilling delayed initial progress but were successfully mitigated with revised drilling methods.

  • The programme was extended from three to nine months to align with rugby and event schedules, ensuring zero lost match days.

 

Results

  • Pitch stabilised: All eight depressions treated successfully.

  • Validated performance: CPT testing confirmed significant improvement in ground stiffness and uniformity.

  • Operational continuity: Matches continued without interruption, avoiding substantial revenue loss and the need for relocation.

  • Programme efficiency: Each treatment area was completed and cleared for use within 24 hours.

  • Carbon savings: Compared with deep excavation, the Geobear solution produced up to 75% less embodied carbon, aligning with the stadium’s sustainability goals.

Future Applications

The project was one of the first of its kind in the UK sports sector and demonstrated the suitability of geopolymer injection for stabilising large playing surfaces on brownfield land.

Potential applications include:

  • Stadiums experiencing pitch settlement or subsurface voiding.

  • Local authority and school sports pitches.

  • Recreational grounds or arenas built on former industrial or reclaimed sites.

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Don't let unstable ground put your business at risk. Our commercial team can provide a clear assessment and a fast, effective solution tailored to your operational needs.

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