Summary
A 91-year-old concrete gravity dam in the Scottish Highlands, approaching the end of its design life, required a comprehensive condition assessment and ongoing monitoring programme to support a life extension decision. Hypotenuse deployed a full-spectrum SHM system that identified three previously unknown defects and provided the quantitative basis for a successful 25-year licence renewal.
Background & Context
The dam was constructed in 1934 to an early design code. No continuous monitoring had ever been installed. The dam owner needed to demonstrate fitness for purpose to regulators under the UK Reservoirs Act 1975 (updated 2020). Manual CIRIA monitoring reports had identified increasing seepage flows but could not determine the cause.
Sensor Deployment
Digital Twin & Risk Modelling
Annual GPR surveys, combined with piezometer data, identified three previously unknown features: a 1.2 m void at the dam-foundation contact, a zone of increased permeability at the right abutment, and a horizontal crack at elevation +24 m consistent with an historic foundation settlement event.
The Hypotenuse platform correlates seepage flow with reservoir level, temperature, and seasonal groundwater levels to separate normal thermo-elastic seepage patterns from trends indicative of internal erosion. For the right abutment anomaly, a dedicated alert threshold was established based on hydraulic gradient analysis.
Key Outcomes & Results
Defects Identified
3 previously unknown structural defects located and characterised
Licence Renewal
Quantitative monitoring data supported successful 25-year life extension
Seepage Source
Cause of increasing seepage trend identified — attributed to right abutment drainage deterioration (corrective grouting undertaken)
Baseline Established
First-ever continuous monitoring baseline for a 91-year-old structure
Regulatory Acceptance
Full CIRIA 164 / ICE reporting compliance achieved
91yrs
Structure age
3
Defects found
25yr
Licence renewed
148
Sensor channels
Deployment Snapshot
Location
Scottish Highlands, UK
Dam Age
91 years
Dam Type
Concrete gravity
Regulatory Framework
UK Reservoirs Act 1975
Sensor Count
148 channels