When One Third of a City's Sewage Hinged on 100 Crumbling Columns: Another Story of Ingenuity Under Sanctions - By Zaid Jurji

Welding of Supporting Cylinder Steel Columns

In 1999, while serving as Head of the Water and Sanitation Programme at UNICEF Iraq, we were approached by the Baghdad Sewage Authority with an urgent plea. The Al-Karkh conveyance channel; a critical piece of infrastructure serving the western half of Baghdad, was on the verge of collapse.

This was the sanctions era. The Oil-for-Food Programme was in place, but it came with a fundamental constraint: Iraqi authorities had no control over cash. The OFFP could supply equipment and materials, but funding local works required navigating a labyrinth of restrictions. Once again, conventional solutions were off the table. We had to think differently.

This is the story of how a small team of UNICEF national engineers saved a piece of infrastructure that Baghdad depended on and with ingenuity, precision, and a fraction of what a conventional rebuild would have cost. But more than an engineering triumph, it was a lesson in what service truly means. There is no greater reward than serving your community. To serve your people, your friends, and their families is a unique privilege. It asks you to give everything; to attempt the impossible and make it possible. The feeling of giving back is beyond description.

The Context: A City Built on Flat Land

Baghdad sits on remarkably flat topography. This simple geographical fact shapes everything about how the city manages its sewage. Wastewater cannot flow by gravity alone over long distances. Instead, the system relies on a cascade of pumping stations that lift sewage back up, again and again, to keep it moving toward treatment.

Al-Karkh Treatment Plant serves the western part of the city, designed to handle approximately 270,000 cubic meters of sewage per day and serving around 1.8 million people.

The system works like this: a network of pipes collects sewage from homes and neighborhoods, flowing by gravity through carefully sloped pipes. When the pipes reach a certain depth, a pumping station lifts the sewage back up. This repeats across the city. At the final stage, the sewage is pumped into an open conveyance channel, which carries it to the treatment plant.  That channel was the problem.

The Problem: A Channel Falling Apart

The Al-Karkh conveyance channel was 1.5 km long, composed of open concrete segments 3 meters high, 6 meters wide and 8 meters long, all lined with a bituminous layer for concrete protection. These segments sat on concrete beams on both ends, which were supported by over 100 concrete columns, each 40 cm × 40 cm. Depending on topography, some of these segments were sitting directly on ground level.

The channel was poorly constructed. Its joints leaked. Along its journey, the sewage becomes septic and organic matter results in acids which are corrosive and attack the concrete.

The results were predictable and devastating:  The concrete on the columns began to peel, exposing the reinforcing steel, which in turn got corroded, thus drastically reducing each column's bearing capacity.

Worse still, the soil beneath the channel was characterized by very high levels of gypsum. When the leaking sewage mixed with the gypsum, it dissolved the underground deposits, creating voids and causing the soil to collapse.

The footings settled. The columns sank. The entire structure was failing.

The potential consequence was catastrophic: the total collapse of the channel would mean that the untreated sewage of nearly a third of Baghdad inhabitants, would discharge freely into the environment. The pollution and public health disaster that would follow was almost unthinkable.

The Solution: Engineering Creativity Under Pressure

The UNICEF WASH team was tasked with finding a solution. The works were led by my colleague Emil Sequeira, a brilliant structural engineer. We were both graduates of the same engineering school. He earned his BSc and MSc in structural engineering, while I earned mine in water resources engineering. He was the top of our class for four years running. Works focused on two fronts:

1. Stop the leakage.
The leaking joints were the root cause. Without stopping the leaks, any repair would be temporary. We needed to stabilize the structure and prevent further deterioration.

2. Repair and reinforce the structure.
Some columns were minimally affected. Others were severely damaged. The repair strategy had to address both.

For the damaged columns, we:
- Cleaned the exposed reinforcement and removed all peeling concrete.
- Repaired the structural damage as thoroughly as possible.

But we knew that repair alone would not restore full bearing capacity. To prevent any future collapse, we introduced new steel columns alongside the damaged concrete ones.

These steel columns were ingenious in their simplicity: each was composed of two cylindrical sections, one slightly larger than the other, allowing them to be adjusted and installed beneath the existing concrete segments. Once in place, hydraulic jacks were used to apply load, and the two sections were welded together—transferring the weight of the channel onto the new steel supports.  Beneath each steel column, a new concrete foundation was constructed.

3. Restore the soil.
The gypsum soil had been weakened by years of leakage, creating voids and gaps. To address this, we injected cement mortar through hundreds of injection points, filling the underground gaps and stabilizing the soil strata.

4. The impossible section.
In one area, the damage was so severe that the soil was thought to be beyond repair. Here, we took a different approach: two steel trusses were constructed, with their bases extending beyond the width of the channel. One end of each truss was fixed; the other was jacked up using hydraulic jacks. Once the required level was reached, steel sheets were inserted to fill the gap, creating a stable support system.

The Outcome: Maximum Impact, Minimal Cost

The results were remarkable. The channel restored its structural capacity. It continued to convey sewage safely to the treatment plant. A catastrophe was averted.

And it was achieved with a relatively small financial amount. Thanks entirely to the ingenuity of the UNICEF WASH team. There was no massive reconstruction contract, just a simple one. No imported heavy machinery. Just smart engineering, careful planning, and the courage to try solutions that had never been attempted before.

Final Reflection

This project, like the Al-Rasheed Water Treatment Plant rehabilitation, stands as a testament to what is possible when constraints force creativity. Under sanctions, with limited resources and no access to conventional solutions, we found a way.

UNICEF stood tall as the main supporter of Iraq's water and sanitation sector during the sanctions era—not because we had unlimited resources, but because we had committed, creative engineers who refused to accept that a city of millions should be left without essential services.

This is the kind of work that makes me proud. Not just the engineering, but the mindset: when the obvious path is blocked, build a new one.

Reinforcement of additional concrete foundation

Preparing the jacking process of the trusses

Completed repair works under one segment