3km Drilled, Newcastle Mine Void Case Study

Project: Newcastle East End

Location: CBD

Client: Keller Pty Ltd - Mine Fill

Scope

Drilling of 300 holes initially with more holes to be added as voids are encountered. Currently drilling 145 boreholes through two separate voids down to 90m. Borehole imaging used for deviation and extent of the voids. Boreholes will allow grout lines to fill voids in the future.

Key Plant

The Comacchio 450P track mounted drilling rig with specially designed Polycrystalline Compact Diamond (PCD) bit to maximize meterage. The smaller Geoprobe 7822Dt was used for some difficult access holes.

Challenges

Drilling near city centres always has its challenges. With proximity to traffic and equipment manoeuvres between closely spaced holes, crew and public safety is important. The drilling was also conducted while nearby buildings were being demolished. Due to drilling in the city centre, there could be no run off of any fluids from the drill site onto public roads or entering the stormwater system.

Specific Controls in Place

Drilling near city centres always has its challenges. With proximity to traffic and equipment manoeuvres between closely spaced holes, crew and public safety is important. The drilling was also conducted while nearby buildings were being demolished. Due to drilling in the city centre, there could be no run off of any fluids from the drill site onto public roads or entering the stormwater system.

Achievements:

Multiple holes drilled over the weekend with two rigs on the busier streets. Boreholes were drilled with little to no deviation. Conducted PCD drilling with 99mm PCD bit and HWT casing to find workings. If voids were encountered the casing was left in the ground. Continued PCD drilling to the end of the hole.