Refuge in water: TH10 in Uganda

7 August 2020

Quenching a million thirsts takes teamwork with Uganda’s growing population. One million South Sudanese refugees have moved across the border into Uganda since July 2016. In the northern Gulu Region, this already heavily populated area supports the influx through NGOs and government entities working together.
With a nearly perfect climate, Uganda is rich in food. Tree fruits supply a seemingly endless garden, grain crops are harvested twice annually, and beef cattle, chicken, goats, and swine are abundant. Refugees are often given small plots of land to farm and feed themselves. Although food is plentiful, water is not. Drilling for water is essential. To prevent people from spending valuable time each day collecting water, the government requires a well and hydrant for pumping fresh water for communities with 200 or more people. Wells can’t be further than 3 miles (5 km) from each other.
Epiroc TH10 waterwell drill rig in Uganda
BM Watsan Holdings has drilled many wells with the TH10 it purchased in 2014. The company can mobilize on a location, have a well drilled, pump installed, and construction completed in three days. BM Watsan Managing Director of Projects, Olanya Joseph Otim, said the company’s success comes due to a good relationship with the entities it works for. “We make their job easier because they can trust us to complete the well,” he said.

Otim said the company averages 50 wells a year, adding that the wells here are not deep. The deepest to date was less than 395 feet (120 m). “The TH10 is fast, taking just five to seven hours to complete a well.”
The development of a well requires a 12-inch (305 mm) surface hole for a temporary steel surface casing. A 6 ½- (165 mm) or 7-inch (178 mm) hole is drilled to depth with an air hammer. The company uses Secoroc QL 60 hammers with button bits drilling through the rock.

"The TH10 is fast, taking just five to seven hours to complete a well."

Olanya Joseph Otim, Managing Director of Projects

The TH10 works well for both mud and air drilling because it comes with a Centerline 3×4 mud pump and a Deutz deck engine. Driller David Okello said he has plenty of power to drill with either mud or air. “The surface has rocks and boulders that make mud drilling difficult. I am cautious not to get stuck. I’d never get out.”

 

Air drilling rock goes fast and easy. “If we start a hole at 8 a.m., we’ll finish  by 3 p.m.” The goal is to get sufficient flow for the hand pump - a minimum of 130 gallons (0.5 m3) per minute. Anything less is considered a dry well and is abandoned.

Okello knows the quality of water by region, but ground conditions are not as predictable. He generally hits rock within 30 to 60 feet (10 m to 20 m), but it ranges from 3 to 100 feet (1 m to 30 m). The rig’s mud pump is rated to flush the hole to more than 330 feet (100 m), so he’s not worried about the depth of his starter hole. Once the temporary surface casing is set, drilling continues with a 7-inch bit.
Epiroc TH10 waterwell drill rig in Uganda

The well is cased with 5-inch PVC pipe to depth and backfilled with cuttings. For the top hole, the casing is set with a concrete seal. This top hole is a sanitary seal 3 meters from the surface. As Okello is air drilling the 7-inch hole, he tracks the fracture zones he passes. They will perforate the PVC casing at each zone.
  

The air package to drive the hammer is an Atlas Copco XRH 836 compressor delivering 836 cfm (395 L/s) at 300 psi (26 bar). 

 

The TH10 is built with a heavy-duty TATA SA 1212 TC truck with all-wheel drive. The truck has more than enough power to get them where they need to go. Okello said he’d buy this same drill if he were to buy another, but the next time with a 6×4 drive for areas where they need better traction. 

 

The deck engine powers two hydraulic motors that drive the torque and speed of the rotary head. These motors drive gears that provide torque and speed. Maximum torque is 3,746 lbf-ft (5,070 Nm). The driller has variable control of speed from 0 to 85 rpm. 

 

Okello said while there are heavier drills with more pullback, the TH10 is a good fit for their operation and completes shallow wells quickly and efficiently. “I like the performance and enjoy drilling with it.”

 

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