An EPC Contractor’s Perspective
FEATURED PAPER
By Rahmat Ilham Zazzali
Indonesia
ABSTRACT
This paper examines how an engineering, procurement and construction contractor can organize storage tank overhaul scope for integrated cost and schedule control. Drawing on the author’s experience in Indonesian refinery projects, it develops a work breakdown structure (WBS) approach for tank work using the jacking method. The approach links the contract WBS, subcontract WBS, work packages and WBS Dictionary, with reference to NORSOK Z-014 and OmniClass classification concepts. An eight-attribute document assessment produces scores of 12/32 for the contract WBS, 16/32 for both the subcontract WBS and work packages, and 27/32 for the WBS Dictionary. The dictionary exceeds the study’s screening threshold of 22/32. This result supports using the dictionary to document and connect scope, responsibility, budget, schedule and acceptance requirements; it does not establish that the other documents are unnecessary. A weekly earned value example illustrates the calculation of cost and schedule indicators. The paper presents a practitioner framework and illustrative calculations, rather than a validated demonstration of improved project outcomes. Its practical contribution is a consistent information structure for estimating, handover and project control.
Keywords: earned value management; work breakdown structure; WBS Dictionary; storage tank overhaul; EPC contractor; cost estimating; project control.
1 INTRODUCTION
Engineering, procurement and construction (EPC) contractors must translate contractual scope into an executable plan while controlling cost and schedule exposure.
In the author’s experience with Indonesian refinery projects, tender bills of quantities and work breakdown structures have differed between refinery units, even for similar tank work. The contractor therefore has to develop sufficient detail for estimating, scheduling and execution. If that detail is not transferred consistently from the tender team to the project team, the basis of the budget can become disconnected from the work being monitored.
This paper focuses on the mechanical scope of storage tank overhaul, using Tank 610-TK-207 as the case reference. It considers how a repeatable WBS and its supporting documents can connect estimating and scheduling to earned value management (EVM). The case scope includes fabrication and installation associated with the tank bottom, annular plates, shell, roof and accessories. The intention is to establish a contractor’s internal structure that can be mapped to client and subcontract reporting requirements.
The construction method affects how work is packaged and sequenced. Dey (n.d.) describes conventional tank erection and the jacking method, in which upper shell courses are assembled before successive lower courses. In the author’s experience, the jacking method can reduce work at height and the need for extensive scaffolding. These observations are method-specific considerations for planning; they do not remove the need for an approved lifting method, safety controls and inspection requirements. Figure 1 provides context from the author’s tank-work experience.
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How to cite this paper: Zazzali, R. I. (2026). Earned Value Management for Storage Tank Overhauls: An EPC Contractor’s Perspective. PM World Journal, Vol. XV, Issue XI, November. Available online at https://pmworldjournal.com/wp-content/uploads/2026/11/pmwj170-Nov2026-Zazzali-EVM-for-Storage-Tank-Overhauls.pdf
About the Author
Rahmat Ilham Zazzali (Ilham)
Indonesia
Rahmat Ilham Zazzali is a Project Management Professional with over 14 years of experience in the upstream and downstream oil and gas sectors, including extensive international work in Libya. He holds PMP® and CCP® credentials and currently serves as a Senior Quantity Surveyor at PT Wasco Engineering Indonesia. Previously, he worked with Waha Oil Company in Libya, managing EPC, operations and maintenance (O&M), and plant services projects. A featured keynote speaker at the 41st Indonesian Petroleum Association (IPA) Convention in 2017, he holds a Bachelor’s degree in Mechanical Engineering from the National Institute of Technology (ITN) Malang, Indonesia. He can be contacted at ilhamzazzali@gmail.com
