The slope at the Kariangau Offshore Supply Base (KOSB) is very vulnerable to erosion and landslides. The location also has a low seismicity level and presence of coal and clayshale. Certain substances contained in coal can oxidize the retaining structure material if the coating on the system is not adequate. Products from Maccaferri such as Terramesh system, MacGrid WG, and MacMat EM were chosen to deal with the problem.
Kariangau Offshore Supply Base (KOSB) Fuel Terminal is a fuel terminal located in Balikpapan, East Kalimantan. It serves as fuel storage for various industries.
PT. Petrosea, Tbk. needed a retaining structure for slope protection of the access road that connects the port and the fuel terminal. The slope to be protected has various height, ranging from 20–30 meters. Few slope failures and erosion occurred from 2015 and slope remediation has already been done on 2016. The location also has a low seismicity level and presence of coal and clayshale. Certain substances contained in coal, typically the iron sulfide (FeS2) can oxidize the retaining structure if the coating on the system is not adequate. In addition, the clayshale character with high shear strength when unexposed, can lose its shear strength when exposed to air and water, this adds challenges to the Kariangau project. These things can cause problems if inappropriate measures are carried out.
The initial solution was mass gravity retaining structure with gabion and woven geotextile. PT. Maccaferri Indonesia proposes a hybrid MSE Wall structure called the Terramesh System as an alternative replacement. Mainly, the Terramesh System consists of anchored gabion made from double twisted steel wire hexagonal mesh called Terramesh and woven polyester geogrid called MacGrid WG. The Terramesh units, considering the presence of the coal layer at the project location, were coated with Zinc 95% – Aluminum 5% and PVC. The MacGrid WG is also coated with PVC in order to maximize its durability. In order to prevent water infiltration to the system, drainage geocomposite called MacDrain was installed behind. Finally, the erosion control mattress called MacMat EM was installed to protect the slope above the Terramesh System from water runoff, rainfall, and other factors that can cause erosion.
The structure was designed using limit equilibrium method software. Both static and seismic analysis have been performed. Finally, the hybrid MSE Wall solution called Terramesh System proposed gave savings of material cost of nearly 38% comparing to mass gravity structure with gabion and woven geotextile.
Don’t hesitate to contact us if you have any questions.