While a conventional churn drill could penetrate the rock at 1 to 2 ft.
Many operations used churn drills or wagon drills - a pneumatic drill mounted on a single-axle frame that had to be towed to where it was needed.
In 1910 on Valdez Creek, miners used a churn drill for exploration.
By comparison, miners using cable-driven churn drills 30 years ago could bore about 20 holes a day at 14 feet per hole to bedrock.
A RotoSonic drill produces a similar sample size as the churn drill.
Drill samples from the initial 10 churn drill holes and the first four RotoSonic drill holes have been sent to SGS Lakefield in Canada for analysis and it is anticipated the first results from the drill holes will be available by mid-May 2010.
Phase 1 is a Banka or Churn drill
program to delineate the extent and nature of the gravels at an estimated cost of US$350,000.
A total of twelve (12) large diameter churn drill
holes, aggregating up to 500 meters total length have been recommended.
Deep churn drill
hole results obtained by previous operators in the late 1950's indicate that the mineralization persists 200 metres below the level of the Gibraltar confirmation drilling.
were the standard method, and these were slow.
To complete the drilling program, MGOL will be using two churn drills
, two SonicSampDrill CRS-V drilling units with crawlers, and is under contract with SonicSampDrill to provide four additional drill masters to operate the CRS-V units.
Vintage drill hole logs show drill holes penetrated this cover but encountered intensely hard altered sedimentary rock (hornfels) that was too hard to be penetrated by the churn drills
of the era.