Clean water in Bangladesh guaranteed for many years
By examining and preparing a remediation proposal for a newly built section of a purification plant in Bangladesh, FORCE Technology helps ensuring the supply of clean drinking water.
Scarcity of drinking water
Clean drinking water is an article in short supply in a developing country such as Bangladesh. The surface water is polluted, the ground water has a high content of the heavy metal arsenic and the water table is at a depth of 75 metres, which makes it difficult to drill for clean water. Therefore, the purification plant uses water from the neighbouring river, which is often just as dirty as our sewage water.
To increase the capacity, the existing purification plant has expanded their plant with a phase 2 section, which is a copy of the existing plant, which has worked well for 10 years. However, phase 2 has been built with fewer joints, i.e. by casting larger segments at a time.
Impartial reviewSince a number of cracks had been observed in the newly cast concrete process unit, the owner required an impartial review of the total construction. FORCE Technology was requested by the construction contractor to inspect the tanks and assess what impact the cracks would have on the remaining service life. We reviewed phase 1 to get a reference – what should the plant be able to endure? And how are the operating conditions?
Then we examined the construction visually in phase 2 and registered all the cracks. We also reviewed the repairs that had already been performed, to see whether they had been performed correctly. In some cases the performed work did not meet the requirements according the specifications and had to be performed once again.
Furthermore, the concrete was inspected and it turned out that it had been prepared in way, which required thorough curing in order to prevent cracking. Another reason for the cracking was that wall sections were cast in large segments, which in combination with the complicated mix design, increased the possibilities for cracking under the tough curing conditions with the high ambient temperature.
The service life will lastOur assessment is that the purification plant’s phase 2 may last the estimated service life of 50-60 years if the observed cracks are repaired according to specification. Clean drinking water for the population should thus be ensured for many years to come.