Structural Investigation of Dam Spillway Infrastructure

GBG Group Australia was engaged to undertake a structural condition assessment of a dam spillway as part of an asset review program. The structure had exceeded its original design life within a broader infrastructure scheme, and surface defects identified during inspection required further investigation to determine their severity and implications.

The investigation was designed to provide a non-intrusive assessment of the structure while maintaining full operational integrity. Due to the scale and geometry of the spillway, rope access techniques were utilised to safely access and assess all required areas.

To assess the structural condition of the spillway, including identification of subsurface voids, evaluation of water stop joints, and verification of construction details, to support ongoing asset management and future planning.

The investigation utilised a combination of Ground Penetrating Radar (GPR), covermeter survey, Schmidt hammer testing, tap testing, and drone photogrammetry.

GPR was used to identify potential subsurface voids and confirm slab construction details against archive drawings. Covermeter testing was used to assess reinforcement depth and layout, while Schmidt hammer testing provided an indication of in-situ concrete strength.

Tap testing was undertaken to identify areas of surface delamination, and drone photogrammetry was used to support visual condition assessment and mapping of surface defects.

This integrated approach enabled comprehensive assessment of both surface and subsurface conditions without the need for intrusive investigations.

The investigation confirmed that the spillway structure is performing well, with limited subsurface voids or anomalies identified.

Assessment of the water stop joints indicated that they are performing better than expected, with observed scouring defects largely confined to surface conditions rather than indicative of deeper structural issues.

GPR results confirmed that the as-built construction aligns with archive drawings, providing increased confidence in the structural model. In addition, in-situ concrete strength testing returned values exceeding original design specifications, supporting the continued serviceability of the structure.

Overall, the investigation provided a clear and reliable assessment of structural condition, enabling informed decision-making for maintenance, risk management and future infrastructure planning.

A great example of collaboration between project teams, specialist access crews, and NDT methods supporting the ongoing management of critical infrastructure.