Improving Accuracy of Production Volume Reconciliation and Reducing Dumping Rollover Safety Risk Through Vessel Modification Using UHMWPE Lining on Dump Truck Mercy 2528 in Basalt Mining Hauling Operations

Abstract

Carry back — residual soil and clay material adhering to the vessel of dump trucks after dumping — has long been treated as a minor operational nuisance in basalt mining hauling operations. In practice, however, it carries a dual consequence: it directly distorts production accounting, because the volume recorded by Joint Survey (topographic reconciliation) diverges from the volume recorded by Truck Count, and it creates an uneven, off-balance vessel load during the dumping maneuver, a condition independently documented by mine safety regulators as a contributing cause of haul truck tip-over and rollover incidents. At the basalt mining project of PT Putra Perkasa Abadi, Site PT Maruwai Coal, baseline data from January–February 2026 recorded a Joint Survey vs Truck Count achievement of only 76–77%, equivalent to an average monthly revenue loss of approximately Rp370,019,109, alongside an internally assessed dumping-rollover risk rating of S15 on the site risk matrix. A Pareto analysis of the January–April 2026 deviation confirmed that the two earliest months alone accounted for 75.9% of the cumulative loss, while root cause analysis using a cause-and-effect (fishbone) diagram identified the dominant factor as the existing mild-steel vessel plate of Dump Truck Mercy 2528, which is unsuitable for hauling high-moisture soil and clay due to its high coefficient of friction. Contributing but non-dominant factors were inconsistent operator loading practice and the absence of a weekly Joint Survey monitoring system. A structured Quality Control Circle (QCC) intervention was implemented from March to June 2026, consisting of (1) lining the vessel with Ultra High Molecular Weight Polyethylene (UHMWPE) plates, a material with a very low coefficient of friction that prevents wet material from adhering to the surface, (2) in-class operator training on loading consistency, and (3) a new weekly Joint Survey monitoring standard operating procedure. Following the intervention, the Joint Survey vs Truck Count achievement increased progressively to 94–95% in March–April and reached 100% in June 2026, the dumping-rollover risk rating was reduced from S15 to L3, and no loss-time injury related to vessel dumping was recorded during the evaluation period. The projected annual gain in reconciled revenue was estimated at Rp4,137,829,310.88 against an annualized improvement cost of Rp302,400,000 for two plate replacement cycles. These results indicate that a low-cost material engineering intervention, when combined with human-factor training and a systemic monitoring safeguard, can simultaneously improve production volume reconciliation accuracy and substantially reduce the safety risk associated with unbalanced vessel loads during dumping.