The effect of rock quality on the costs of excavation work in infrastructure projects
Soil Report highlighted the Soil en" (i.e. non-rippable by Ripper
type as "Weak to Strong Silt- equipment". Since the major pro-
stone "with UCS value ranging ject time was lost, to overcome
from 11.88 to 62.92Mpa for the the delay due to above, contrac-
excavation .During detail Engi- tor was left with no option other
neering Soil investigation also it than "Blasting" which was cost-
was confirmed as "Conglomet- lier and not considered in their
ric Limestone inter-bedded with project cost.
Siltstone beds" with UCS value Blasting is a special type of ex-
range from 21.7 to 31.7 Mpa.
cavation having so many con-
The main purpose of this article After Contractor started the ex- straints and special require-
is to share an awareness about cavation work with preliminary ments, hence excavation work
an issue came across in one of Dozer, then with Rock breakers. for all structures to be completed
DEWA projects by which con- Rock breaker were broken down in one time in conservative man-
tractor faced huge financial loss repeatedly (Figure 2). Then only ner without leaving any option for
due to overlook of Rippability contractors were realized and additional excavation and con-
phenomena of Rock during ex- did thorough investigation Rock siderable quantity of road base
cavation.
type and carried out assessment backfill which was an additional
The Contractor priced the ex- for correct excavation technique. cost to compensate extra ex-
cavation work as tradition type It was found that the rock type cavation due to blasting option.
of soil even though in Tender was fall under "Blast to Loos- This resulted huge financial loss
Articles
12

---