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Drilling under high scrutiny

July 19, 2022

Habitat protection area requires environmentally responsible drilling practices.

AZCA Drilling & Pump services customers in Arizona and California from its Ehrenberg and Marana, Arizona offices. In this tortoise-inhabited region, AZCA must operate while complying with some of the nation’s most restrictive regulations and those required by its domestic, agricultural, forestry, and government customers. California regulations and new federal emissions requirements influenced AZCA owner Larry Siddall to upgrade to a TH60 deep hole drilling rig.


Siddall accepted delivery of the new TH60 while drilling two 12-inch water production bores and three 4-inch monitoring wells for a ground-mounted solar panel photovoltaic electricity farm.

Epiroc TH60 water well drill rig

The single-engine simplicity of PTO-powered drilling from the TH60’s EPA 2013-compliant 600 hp (447 kW) carrier engine made it attractive to Siddall in this service area.


The TH60 gives AZCA the same capabilities as the T3W they traded in, with 70,000 lbf (311 kN) of pullback and 30,000 lbf (133 kN) of pulldown. With only one engine, the rig’s overall weight is lighter. The deck has more open space. The single-engine rig also has a quieter drilling environment since the engine is farther away from the driller’s station.


Another TH60 difference is its unique cylinder feed design. Its inverted cylinder allows the larger side of the piston to be used for pullback force, resulting in more pullback force at the same hydraulic pressure as non-inverted cylinder rigs. Increased hydraulic pump flow to the cylinders allows it to trip out at up to 45.72 meters per minute (150 fpm).

The drillers found a fractured granitic rock at about 107 meters (350 ft) that continued to 152 meters (500 feet) in total depth. Siddall said he would have liked to use a hammer in this formation. Job specifications limited him to mud drilling.

Epiroc TH60 water well drill rig

The crew sealed off each drill site surface with plastic lining and brought drilling fluid onto the site containing approved additives. All fluid was contained in AZCA’s shale shaker box and hauled away for treatment and disposal, as was initial development water. Solids from the shaker box were also contained and hauled away for treatment and disposal. External pits were not allowed.


One well site allowed a drilling area of 232 square meters (2,500 ft2), yet the crew could fit the TH60 in among a pipe trailer, water storage tanks, a shale shaker, treaded loader, and AZCA’s off-board mud pump. Siddall said off-board pumps are standard in the Western U.S. The TH60 easily accommodates the preference with quick connections at its hydraulic manifold.


Water production wells were drilled in two passes, followed by a hole opener PDC pilot and a tricone bit-third reamer. The monitoring wells were drilled single pass with hard-rock tricone bits.


Normally a tortoise can live off its internal water supply for a year or more without a water source. Under distress, a tortoise will void some of this water as a defense mechanism, depleting itself of critical moisture and causing death if it cannot replenish it. Therefore, any construction work permitted near tortoise habitats requires monitoring of the tortoises for signs of distress.


A third-party environmental consulting company surveyed the land, identifying tortoises, their burrows, and activities, monitoring all access points throughout the project.

After the Bureau of Land Management reviewed impact studies, it permitted a right of way in one of the least tortoise-populated areas.


Although the drilling site was only about 2 miles from the main road, it took the drilling crew, tractor-trailer rigs, and water trucks up to 40 minutes to make their way to it.

An ECM accompanied each piece of equipment as it entered or departed the drill site at speeds of 10 mph (16 k/hr) or less. Once a gate had been slid back into place, the drilling crew and accompanying ECM piled soil and rock against its bottom to seal off gaps that might permit a tortoise to crawl under it. The drilling crew also assisted in relocating tortoises that entered the tortoise-free areas.


The modernized gauges and overall reliability of the new TH60 reduced what Siddall referred to as a “high scrutiny” factor. Environmentalists monitored all drilling operations. Siddall was constantly aware of the need for smooth operations. What a driller would think was a minor malfunction might unduly alarm them. Having reliable equipment, he said, reduced any concern.


AZCA’s extra measures helped the desert tortoise and helped the customer maintain regulatory compliance. The power produced by its customer will help California reach the 2016 targets of its Renewable Energy Program initiative.

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