Bearing Capacity Skills Gaps in Gabiley: Why Do Foundations Get Undersized?

Bearing capacity skills gaps in Gabiley produce undersized foundations when the people sizing footings lack the training to turn a soil profile into a safe bearing value in kPa. A site engineer who has never run a plate load test, or who has watched one done badly, will read a trial pit log and default to whatever the previous plot used. The footing width, depth and reinforcement then follow the assumed number. A Gabiley plot that carried a two-storey house on firm ground next door may sit on 2.5 m of loose fill or on black cotton clay that softens in the Gu rains. Nothing in the drawing shows this unless someone measured it.

What is bearing capacity, in terms a Gabiley site team will use?

Bearing capacity is the maximum pressure the ground under a footing can carry before it shears or settles beyond what the structure tolerates. Engineers express it as a safe bearing capacity in kilopascals (kPa), already divided by a factor of safety, so a designer can multiply footing area by that figure to size a pad. Sand and gravel in a dry state can carry several hundred kPa; soft saturated clay may carry 50 kPa or less. A two-storey reinforced concrete house in Somaliland typically imposes working pressures in the range of 80 to 150 kPa under a pad footing, depending on column loads and footing size, so the difference between a firm gravel and a soft clay decides whether a 1.2 m square pad is adequate or a 1.8 m pad, or a raft, is needed.

Safe bearing capacity is not a single national number. It depends on the soil type, the depth of the founding level, the position of the water table, and how the ground behaves when it wets up or dries out. That is why the number belongs to a specific plot, at a specific depth, backed by a field test or at least a logged trial pit with hand penetrometer readings. A figure copied from a neighbouring site is a guess, whatever format it is written in.

Where do the bearing capacity skills gaps in Gabiley come from?

They come from a chain of work where field observation, testing and interpretation are split between people who rarely share a method. In Gabiley and across Somaliland, investigation is often sold as "dig a pit and tell us the depth", so the excavator operator decides where the pit goes and how deep it stops. The operator is skilled at digging, not at reading strata, so the pit frequently halts at the first hard layer, which may be a thin cemented crust over soft material.

The second gap is testing. Plate load tests and cone penetration work need a calibrated plate, a reaction load and a logged loading sequence. Where a contractor owns a plate but has no trained technician, the test produces numbers but not a reliable pressure-settlement curve. The third gap is the interpretation itself: turning a log and a test result into a safe bearing capacity with a factor of safety. That step needs someone who has done it repeatedly under supervision, and Somaliland's small pool of geotechnical engineers is stretched across Hargeisa, Berbera and the larger projects.

The fourth gap is incentives. A developer comparing three quotes for a soil investigation will often choose the lowest, and the lowest quote is usually the one with the fewest tests and the shortest report. That is not corruption; it is a market where the buyer cannot tell a thorough investigation from a thin one. Elsewhere in Somaliland, underbidding on soil sampling has been examined before, and the pattern is the same wherever buyers lack a checklist.

How does the gap turn into undersized foundations?

An undersized foundation happens when the assumed bearing capacity is higher than the real one, or when the founding depth misses a weak layer. Three ground conditions in the Gabiley area cause most of the trouble.

• Loose fill and made ground. Plots levelled with uncontrolled fill from earlier excavation look flat and firm at the surface. The fill compacts unevenly, and a pad founded on it settles more than the design allows.
• Black cotton clay. These expansive soils shrink in the dry season and swell when the Gu rains arrive. A footing cast into wet clay at a shallow depth can lift and crack a wall above it, and the safe bearing capacity falls sharply when the clay is saturated.
• Shallow hard crust over soft material. A cemented layer a metre down can fool a trial pit into stopping early. The pad then bears on the crust, which punches through under load.

When any of these combine with a bearing figure copied from a nearby plot, the footing comes out too small, too shallow, or both. The building may still stand for a season. Cracks appear at wall corners and around door openings after the first wet season, and the repair cost lands on the owner, not on whoever signed the drawing.

How do you detect a bearing capacity claim that was never properly tested?

You detect it by asking for the raw record and comparing it with the design. A report without a field log, a test date, a plate size or a settlement reading is a narrative, not evidence. Ask for these items in writing:

1. The trial pit or borehole log, with depths, strata descriptions and the groundwater level at the time of work.
2. The field test record: plate diameter, load increments, settlement at each increment, and the equipment calibration date.
3. Lab results where samples were taken, including moisture content, Atterberg limits and any shear strength test.
4. The interpretation page: the chosen safe bearing capacity in kPa, the depth it applies to, the factor of safety used, and the author's name and qualification.
5. The structural drawing showing the footing size that the figure produces, so the two numbers can be checked against each other.

If the answer to any of these is that the report is with the contractor or the numbers were agreed verbally, treat the bearing capacity as unverified. You can also walk the site after rain and look for standing water in the trial pit area, which tells you how the ground behaves when saturated.

What does a competent investigation cost, and who should pay for it?

A competent investigation is a small fraction of the foundation cost, which is why the argument for cutting it rarely holds. A trial pit with a logged profile, hand penetrometer readings and a written interpretation is the minimum for a single-storey house. For a two-storey building or anything with heavy columns, add at least one mechanical test, either a plate load test or a borehole with standard penetration testing, at the location of the heaviest footing.

I cannot give you a firm price for Gabiley because equipment mobilisation, pit depth and the number of tests change the figure, and quoting a number I cannot source would mislead you. What you can do is ask two or three providers in Hargeisa or Gabiley to quote against the same written scope: number of pits, depth, tests, lab work and a signed interpretation. When the scopes are identical, the price comparison becomes meaningful, and the cheapest bid usually reveals which item it dropped.

The developer should pay the investigator directly, not through the main contractor. When the contractor hires and pays the investigator, the person producing the ground data has a commercial reason to keep the numbers simple, and the client loses the independent check.

How do you close the gap on your own project?

You close it with a written scope, a named competent person, and a design that states its assumptions. Write the investigation scope before you ask for prices, and specify the minimum: one pit per footprint area or per 200 to 300 square metres of built area for low-rise work, taken to a depth of at least 1.5 times the widest footing, and deeper where soft ground is suspected. Require the safe bearing capacity to be stated in kPa at a named founding depth, with a factor of safety between 2.5 and 3.0, which is the normal range for shallow foundations on stiff or dense soils.

Ask the structural designer to show the calculation that converts the bearing capacity into footing width, and to sign the drawing. Put both the bearing capacity figure and the founding depth into the site instruction book so the excavator operator and the steel fixer work to the same number. If the pit reveals fill, clay or water that the report did not mention, stop and get the interpretation revised before pouring concrete. Record the founding level with a photograph and a level reading for every footing, because a later crack investigation will need that evidence.

For repeat developers, the durable fix is training. Send one site engineer and one technician on a short soils and foundation course, or arrange for the geotechnical provider to run a half-day session on how they log a pit and interpret a test. That transfer of method is what prevents the next project from repeating the assumption.

What to do next

Pick one plot you are about to build on and write a one-page investigation scope before you speak to any provider. State the number of trial pits, the minimum depth, the tests required, and the deliverable: a signed safe bearing capacity in kPa at a named depth, with the field log attached. Send it to at least two providers and ask each to quote the same scope line by line. While you wait, visit the Gabiley municipal engineer's office and ask what ground conditions and founding depths local records show for your area, and request any test records they hold for nearby public buildings. If the office keeps no records, ask the oldest excavator operators in town what they hit at depth on the plots around yours, and put their answers in writing as background only. Then compare every bid against the scope, not against the lowest number.