Structural Investigation of Ring Dam Storage Walls using Ground Penetrating Radar in conjunction with Total Ag Services in conjunction with Total Ag Services

Ground Penetrating Radar Baigent Geosciences trialled the use of GPR for dam wall structural investigation in conjunction with Precision Cropping Technologies, Total Ag Services, and on behalf of Central Downs Irrigators. Baigent Geosciences trialled the use of GPR for dam wall structural investigation in conjunction with Precision Cropping Technologies, Total Ag Services, and on behalf of Central Downs Irrigators. The purpose was to determine if GPR could be used to identify potential weak spots. The purpose was to determine if GPR could be used to identify potential weak spots.

The GPR antenna is dragged behind a vehicle. GPR Acquisition

Philip Clapham’s Lone Pine Storage was investigated with GPR. Lone Pine Storage was investigated with GPR. Some weak and stable areas were indicated Some weak and stable areas were indicated Investigation confirmed (dry soil, 3.1m) Investigation confirmed (dry soil, 3.1m) Data and photos follow: Data and photos follow:

GPR section of entire dam wall. Zones for investigation are noted. Zones for investigation are noted. GPR Section

 GPR can see to approximately 6.0 metres approximately 6.0 metres depth. depth.  An estimate of the depth of a suspected weak area can of a suspected weak area can be estimated from the GPR be estimated from the GPR trace. trace.  Black lines indicate suspected weak areas for inspection. weak areas for inspection. GPR shows possible problem areas A B

Dry with roots Indicated Problem Area (A)

Good compacted core. Indicated Sound Area (B)

Jan Lafrenz Surveyed top of wall. Surveyed top of wall. Found stable area (recent repair) Found stable area (recent repair) Found possible weak areas Found possible weak areas Investigated latter for following pictures: Investigated latter for following pictures:

GPR Section GPR section of entire dam wall. Zones for investigation are noted. Zones for investigation are noted.

Jan inspecting suspect area.

Wall structure of test pit.

Further Investigation Obvious stratification in wall, how dangerous is it? Does it warrant full repair or could it develop into a bigger problem? Obvious stratification in wall, how dangerous is it? Does it warrant full repair or could it develop into a bigger problem? J Carlord’s Boxton was investigated and appears sound. J Carlord’s Boxton was investigated and appears sound.

Conclusion GPR can detect changes in dam wall stratification. GPR can detect changes in dam wall stratification. Areas requiring further investigation are indicated. Areas requiring further investigation are indicated. GPR cannot absolutely guarantee if or when a dam wall may fail. GPR cannot absolutely guarantee if or when a dam wall may fail. GPR can only indicate possible problems with dam wall structure. GPR can only indicate possible problems with dam wall structure.