Fill Identification Skills Gaps in Hargeisa: Why Does Uneven Settlement Show Up Later?

Answer first

Fill identification skills gaps in Hargeisa cause uneven settlement when site teams cannot tell soft, organic or loosely dumped material apart from competent natural ground, so it stays under the foundation and consolidates at a different rate from the surrounding soil once the building loads it. Hargeisa sits on a mix of weathered granite, calcrete and old seasonal watercourses, and the ground under one house can change several times across a 30 m plot. A supervisor who checks only that a pit was dug and a test was taken, without reading what came out of it, signs off a building on ground nobody understood. The defect does not appear at handover. It appears in the second or third year, as diagonal cracks above openings, a slab that drops at one corner, or a gate that no longer closes.

What exactly is fill identification, and why is it a judgement skill rather than a test?

Fill identification means deciding what a body of soil actually is and how it will behave under load. A laboratory report tells you what a sample did in a mould. It does not tell you whether the sample came from the layer that will carry the footing.

The judgement runs through a short, ordinary checklist that any site engineer can apply at the pit:

• Colour and banding. Natural Hargeisa ground is usually red-brown weathered granite, pale calcrete or mixed colluvium. A dark grey or black band, or a sharp change in colour with a straight boundary, often means dumped material or an old rubbish or animal-pen layer.
• Smell and organic content. Material that smells sour or earthy when squeezed, or contains roots, ash, charcoal or scraps of plastic and cloth, is fill, not formation.
• Texture and consistency. Roll a moist ball in the hand. A sample that crumbles too easily is loose; one that holds together but feels spongy or greasy under the thumb may be organic or saturated.
• How the pit walls stand. Natural ground usually holds a face reasonably well. Loose fill slumps into the pit, and the spoil heap often looks different from the layer it came out of.
• Moisture. Material noticeably wetter than the surrounding ground hints at a filled old channel, a soakaway or a leaking water tank.

What skills gaps in Hargeisa look like is a person who can do all of this in theory but does not do it on the day. The pit is dug quickly, the log says the single word "soil", a sample is bagged, and the discussion moves to the concrete. Nobody asks whether the layer at foundation level is the same material as the layer 1 m below it.

Why does the gap reach the site in the first place?

The gap reaches the site because the chain from formal training to site practice has several weak links, and each one removes a check without replacing it.

Formal civil engineering teaching in Somaliland is thin. Universities produce graduates, but the volume of graduates relative to the volume of active construction is small, and many site staff learn on the job from people who also learned on the job. That informal route passes on working habits rather than investigation habits.

The local evidence environment is also thin. Where a contract has no site investigation clause, no borehole requirement and no payment line for testing, a contractor has no commercial reason to characterise the ground. Digging a pit and calling it a day costs nothing.

Supervision norms compound it. On many projects the person who should challenge the ground is also the person responsible for finishing the structure on a schedule. Confirming "this is natural ground" takes two minutes and looks like inactivity; ordering another pit takes a day and looks like obstruction.

Add the cost of delay. A client in Hargeisa pays for a full-time supervisor mainly to keep the build moving. A supervisor who stops work to argue about a soil layer is spending the client's money on something invisible. The cheap path is to accept the layer and carry on, and the cost of that decision lands years later on whoever owns the building.

What does the gap actually do to the building?

The mechanism is differential settlement. If a footing rests partly on competent natural ground and partly on loose or organic fill, the two materials compress by very different amounts under the same load. The structure absorbs the difference as distortion.

You then see a recognisable set of symptoms:

• Diagonal cracks running from the corner of a door or window opening, wider at one end.
• A crack in a slab-on-grade that continues into a column or a wall and grows over months.
• Doors and windows that stick, or that swung freely at handover and stopped closing later.
• A floor that slopes enough to show when a ball is rolled across it, or ponding in one corner after rain.
• A fence or boundary wall that rotates or leans relative to the main building.
• Separation where a staircase, veranda or water tank meets the main structure.

Uneven settlement also interacts with everything else on a Hargeisa site. A footing on fill holds water differently from a footing on calcrete, so one part of the foundation may stay wetter and one drier. Water from a leaking tank or a poorly drained yard softens fill further. The two effects add up.

Workmanship defects that look like bad blockwork, bad rendering or bad plaster can trace back to a foundation moving under the whole building. Treating the cracks as a finishing problem and repainting them delays the diagnosis without changing the outcome.

How can a client or supervisor detect the problem without a laboratory?

You can detect most fill problems with your eyes, your hands and a spade. The point is to make the check routine and to put it in writing.

Watch the test pit being dug, not the photographs afterwards. Attend the excavation and ask the excavator operator to stop at each visible change of material. Ask for the depth of each change and write it down in a field book while you are standing there.

Ask three questions at the pit face. Where did this material come from? Is it the same as the layer below? Has anything been dumped here that we know about? Vague answers at a pit face are a warning sign.

Ask for the log, and check that it has a name on it. A pit log should record depth, description, moisture and whether the material is natural or fill. If the log reads "soil" for the whole depth, the work behind it was not done.

Walk the plot after Gu or Deyr rain. Standing water in one part of the plot and not another, or a patch of ground that stays soft for days, points to fill, an old channel or poor drainage. Do this before you pour anything.

Walk a recent building near yours. Find a comparable building finished two to four years ago and look at the cracks, the doors and the external slab. Ask the owner what was built before the plot was developed. This is free, and it gives you a local reference point that no report can replace.

Check the record trail. For anything beyond a small domestic build, a written specification should name who identifies fill, what counts as unsuitable material, and how removal and replacement are measured and paid. If the contract is silent, raise it before signing, not during excavation.

If you need a formal opinion, ask the municipal engineer's office or a geotechnical practitioner what records they require for a plot of your type, and ask a contractor to show you the investigation records from a finished job. What they will and will not provide tells you a lot about the local standard of practice.

What does closing the gap look like in practice?

Closing the gap is a training and process problem, not an equipment problem. The fix is to make the judgement visible and to attach consequences to it.

Train on the local ground, not on slides. Bring the site team to a few open pits in different parts of Hargeisa and have them describe what they see before anyone tells them the answer. Ten pits described in the field do more than a day of classroom work.

Use a written pit log as a standard form. One page per pit, with fields for depth, material, moisture, natural or fill, and a signature. A named signature changes behaviour more than any instruction.

Approve fill sources and compaction before placement. State in writing which imported material is acceptable, how it will be placed in layers, and how each layer is checked. Measure layer thickness with a tape, not by eye.

Hold a payment against records. Link a percentage of the foundation payment to delivery of the pit logs, the as-built foundation drawing and photographs of the excavation. Retention tied to records is the lever that survives a busy week.

Build a local reference library. Keep photographs, logs and crack histories from finished buildings in Hargeisa. The next team inherits real local examples instead of a theory.

Bring the supervisor into the decision early. The supervisor who will sign the foundation should see the pit and the log, not just the summary sheet. People protect what they have personally inspected.

What to do next

Before your next foundation pour, walk the site and look at the excavation you already have. Identify every change of material by eye and write it down with a depth. Then ask the site engineer, in person, to explain what is at the footing level and why that is competent ground. If the answer is vague or the record does not exist, stop the pour and commission a proper pit log or a borehole before you continue. Pay for that investigation out of your own contingency if you have to, and treat the cost as insurance. If you are the engineer, add a one-page pit log template to your site paperwork this week and require a signature on it. If you are a client, ask to see a neighbouring building finished two to four years ago before you sign the next payment.