In the arid regions of northwestern Kenya, where seasonal rivers run dry for eight months of the year, access to groundwater is not a convenience — it is the difference between life and hardship for rural communities. In early 2026, a community water project was commissioned in a remote village in Turkana County, targeting a borehole depth of 220 meters to tap into a fractured basement aquifer identified by a prior hydrogeological survey.
| Project Location | Turkana County, northwestern Kenya |
|---|---|
| Application | Community water supply, livestock watering, small-scale irrigation |
| Target Depth | 220 meters |
| Final Borehole Depth | 226 meters |
| Aquifer Type | Fractured gneiss basement rock, weathered overburden 18-35m |
| Yield Test Result | 20 m3/hour (continuous 24-hour pumping test) |
| Casing Diameter | 165 mm steel casing to 180m, 140 mm screen interval 180-226m |
| Rig Used | Truck-mounted hydraulic water well drilling rig, 300m capacity |
| Bit Configuration | 165mm tricone bit (upper layers), 165mm DTH hammer (basement rock) |
| Total Drilling Time | 4.5 days (including coring, casing, and development) |
The drilling site sat at an elevation of 380 meters above sea level, in terrain characterized by dry sandy overburden underlain by hard Precambrian gneiss with unconfined compressive strength estimated at 120-180 MPa. The first challenge was the surface layer: loose sand and gravel up to 18 meters deep, which required simultaneous casing advancement to prevent hole collapse during drilling. In the dry-season heat (ambient temperatures reaching 38°C), the mud system required continuous monitoring to prevent evaporation losses.
Below 35 meters, the formation transitioned to fresh, hard basement rock. Rotary drilling with tricone bits slowed to penetration rates of less than 1.5 m/hour, prompting a switch to DTH (down-the-hole) hammer drilling using a 165mm bit paired with a 12-inch cubic-feet-per-minute air compressor. Penetration rate immediately improved to 4-6 m/hour, cutting the expected drilling time for the 190-meter rock section by more than half.
The pilot hole was drilled in a single shift using the truck-mounted rig, which was chosen over a crawler rig because the site was accessible by paved and graded dirt road — an important logistical advantage given that fuel and water supplies had to be trucked in from a town 80 kilometers away. The rig's 18-ton truck chassis navigated the final 12 kilometers of rough track without assistance.
At 180 meters, the drilling team observed the first signs of water return — increased air mist and slight reduction in percussion pressure, consistent with intersecting a fractured zone. Drilling continued to 226 meters to ensure penetration through the most promising fracture interval identified on the teleview log. The borehole was developed by air-lifting for three hours, removing drill cuttings and fine sediment from the aquifer before installing the screen casing.
A 24-hour pumping test conducted at a constant rate of 20 m3/hour recorded a drawdown of only 11 meters, with a recovery to within 0.5 meters of static level within 45 minutes of pump shutdown. The specific capacity of 1.8 m3/hour/m indicated a robust, sustainable aquifer that can support the village's water needs for decades.
The completed borehole now supplies water to approximately 1,200 residents, a primary school of 340 students, a medical dispensary, and a herd of roughly 3,000 head of cattle, goats, and sheep. Before the project, villagers walked an average of 6 kilometers each way to collect water from a seasonal riverbed; that burden has been eliminated.
The decision to switch from tricone rotary to DTH hammer drilling at the rock interface was the single biggest factor in on-time completion. Operators who attempt to drill hard basement rock with rotary bits alone routinely see penetration rates drop to 1 m/hour or worse, while DTH hammer drilling in the same formation averages 4-6 m/hour. Matching the drilling method to the actual formation — not just the budget plan — saved approximately three days of rig time on this project.
Looking for a water well drilling rig built for African field conditions? We supply 200-1000m capacity truck-mounted and crawler rigs with DTH and rotary dual-capability, shipped DDP to your nearest port.
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