Fuel Management in Construction: Stop Diesel Theft on Site

On a civil site, diesel is one of your biggest plant costs. It is also the easiest one to steal. A bulk tank, twenty machines and an unwatched night shift can lose a few hundred litres a week. Nobody sees it until month-end, when plant is far over the allowable.

This guide explains how to run fuel management on a South African civil site: tank control, litres against machine hours, theft patterns and the KPIs that catch them. It is for contracts managers, plant managers and site agents. All figures are indicative.

Why Does Fuel Control Hit Your Margin Directly?

Lost fuel comes straight off your margin, because no contract pays you back for litres you waste or lose. Many GCC 2015 contracts include contract price adjustment (CPA) in the contract data. But CPA follows the market price of diesel, not the litres your machines burn.

CPA adjusts what the client pays using Stats SA work group indices, and diesel is part of them. It does not care if your 20-tonne excavator burnt 14 litres an hour or 20. On a fixed-price contract, you also carry the price risk. Our guide to the GCC payment certificate process shows where CPA sits on the monthly certificate.

Every litre siphoned is a pure loss. A CIDB grade 7 earthworks contract with 15 to 25 machines can easily use 50,000 to 60,000 litres a month.

In September 2026, the wholesale price of 500 ppm diesel in Gauteng was about R29.11 a litre, after a DMPR increase of 293.90 cents a litre on 2 September 2026. Coastal prices are a little lower, and the Department of Mineral and Petroleum Resources (DMPR) resets them monthly. This guide uses R29 a litre.

At that price, 55,000 litres costs R1,595,000. A 2% unexplained loss is 1,100 litres. That is R31,900 a month, or R382,800 a year on one site.

Fuel goes missing at three points:

Delivery: the tanker drops less than the note says.
Storage: fuel leaves the tank with no slip.
Issue: fuel is booked to a machine but goes somewhere else.

Measure and compare all three, or the loss simply moves.

How Do You Control the Tank and the Bowser?

Treat your bulk tank and bowser like a cash box: locked, metered, measured and owned by one named person. Give one attendant the keys, lock every outlet, check the flow meter on a schedule and dip the tank every morning. Log every bowser run in and out. One named owner makes every litre traceable.

The controls that work on civil sites:

One custodian. One named fuel attendant runs the tank, with one named stand-in. Nobody else dispenses. When everyone can fill, nobody is accountable.
Locks and anti-siphon. Lock the fill caps, nozzles and pump switch. Fit anti-siphon screens to machine tanks where you can. Keys stay with the custodian and site agent, not on a hook in the container.
Calibrated flow meter. Check each dispensing meter against a calibrated measure on a schedule. A meter that reads 2% high hides 2% theft for good.
Daily dip. Dip the tank at the same time every morning. Convert the reading with the tank maker’s calibration chart. Record any water at the bottom.
Bunded, lit and visible. Most environmental management programmes (EMPs) ask for a bund that holds at least 110% of tank capacity. Add good lighting and, where you can, a camera on the dispensing point.
Bowser runs logged. Dip the mobile bowser when it leaves the yard and when it comes back. Every litre in between needs a slip.

Storage also has legal rules. SANS 10131 covers above-ground petroleum tanks at consumer sites like yours. Many municipal fire by-laws need a flammable liquid permit or certificate above set volumes, so check with the local fire department before the tank arrives. A serious spill can be an emergency incident under section 30 of the National Environmental Management Act and section 20 of the National Water Act. Both set duties to report and clean up.

Site rule worth enforcing: no slip, no fuel. If an operator cannot give a fleet number and an hour meter reading, the attendant does not dispense. Every exception becomes a theft channel within a month.

What Should a Fuel Issue Slip Record?

Every fuel reconciliation depends on the issue slip, so design it to be hard to fake. A good slip carries a pre-printed number, the fleet number, the hour meter reading, the litres with pump readings before and after, two signatures and a cost code. Without the hour meter reading, you cannot work out litres per hour.

A good slip records:

a pre-printed slip number, the date and the time;
the fleet number;
the hour meter reading (SMR, service meter reading) for yellow plant, or the odometer for trucks;
the litres dispensed, with the pump meter reading before and after;
the operator and attendant signatures;
the cost code or activity.

The day’s slips must add up to the pump meter movement. If the pump moved 1,450 litres and the slips total 1,300, then 150 litres left without paper.

The hour meter reading matters just as much: without it there is no litres per hour, and litres per hour catches most fraud.

How Much Diesel Does Each Machine Use per Hour?

Divide the litres issued to a machine by the hours it worked, then compare the result with a benchmark for that machine. As a guide, a 20 to 22 tonne excavator uses about 12 to 18 litres per hour under mixed load. If a machine drifts above its own baseline, you have a mechanical problem or a fuel control problem.

The ranges below are estimates under typical mixed load. Ground, operator and machine age all change them, so build a baseline from the first month of clean data per fleet number.

Plant type	Typical size	Indicative consumption
TLB (backhoe loader)	70 to 75 kW	6 to 9 L/h
Excavator	20 to 22 t	12 to 18 L/h
Excavator	30 to 35 t	18 to 26 L/h
Motor grader	140 class	12 to 18 L/h
Dozer	D6 class	18 to 26 L/h
Front-end loader	950 class	12 to 18 L/h
Smooth drum roller	10 to 12 t	7 to 11 L/h
Articulated dump truck	25 to 30 t	15 to 22 L/h
Tipper or water bowser truck	10 m³ / 10,000 to 18,000 L	35 to 50 L/100 km
Generator	100 kVA at 75% load	16 to 20 L/h

Worked example: a 20-tonne excavator on bulk earthworks logs 180 working hours in a month. Its slips show 3,600 litres, which is 20 L/h. Its baseline from the last two months is 14 L/h. The gap is 6 L/h, or 1,080 litres. At R29 a litre, that is R31,320 on one machine in one month.

Before you call it theft, check the machine: a clogged air filter or worn injectors push consumption up. If the machine is fine, check fill times, who was on duty, and whether fills match the daily plant return.

How Is Diesel Stolen on Civil Sites?

Most site fuel fraud follows a few patterns: siphoning, fake issue slips, ghost plant, short deliveries, inflated hours, private use and water dilution. Each one leaves a trace in the numbers, usually in the daily dip, litres per hour or the plant return. The table shows where to look.

Fraud pattern	How it works	Where it shows up
Siphoning	Fuel drained from tanks or machines at night	Daily dip below book stock; machines needing fills early
Fake issue slips	Slips written for fuel that never went into a machine	L/h above baseline; fills on days the plant return shows the machine idle
Ghost plant	Fuel issued to a fleet number that is off hire, broken or on another site	Slips for a machine with no hours, or with an open job card
Short delivery	Tanker drops less than invoiced, sometimes with help from site	Dip before and after delivery does not match the delivery note
Inflated hours	Machine left idling, or a false SMR written on the slip, so extra litres look normal	SMR hours higher than the plant return, telematics or work done
Private use	Fuel for bakkies or home generators, or sold on	Light vehicle consumption creeping up; stock variance with no plant cause
Water dilution	Water added to hide a shortfall	Water on the dip stick; filter and injector problems

Ghost plant is the most underrated: fuel keeps going to a machine that left for another site two weeks ago. Keep fuel and plant records side by side.

The Daily, Weekly and Monthly Routine

A routine beats a month-end investigation, because a variance found today can still be explained. One found 30 days later usually cannot. Dip and check slips daily, check every delivery, review litres per hour weekly and reconcile stock and cost per unit of work monthly.

Daily (attendant and site agent): dip at the start of shift and check the slips against the pump meter. Then compare book stock (opening dip, plus deliveries, minus slips) with the next morning’s dip.
At each delivery: dip before and after offloading, with the driver present. Query any shortfall before anyone signs the delivery note.
Weekly (plant manager): check litres per hour per fleet number against baseline. Flag anything 10 to 15% above. Match slips to the daily plant returns.
Monthly (contracts manager or QS): do a full stock reconciliation and work out fuel cost per unit of work done.

A simple month-end stock reconciliation looks like this:

Line	Litres
Opening stock (dip, 1st of month)	8,000
Plus deliveries (verified by dip)	60,000
Less issues (per slips)	58,500
Expected closing stock	9,500
Actual closing stock (dip)	8,300
Unexplained variance	1,200 (about 2% of issues)

At R29 a litre, that gap is R34,800 for the month. Temperature and measurement error explain some variance, because diesel expands by about 0.8% for every 10°C. Many contractors set a tolerance of about 0.5% to 1% of throughput. Anything above that needs a written explanation from site.

Keeping Records When the Site Is Offline

Fuel records fail first on remote sites, because the slip book lives in the container and the spreadsheet lives at head office. A pipeline 80 km from town, with no signal, is where losses are highest and data is thinnest. The answer is capture at the pump on a device that works offline and syncs later.

Capture each issue at the pump (fleet number, SMR, litres) on a phone that works offline and syncs later. Head office then sees litres per hour during the week, not at month-end. Keep fuel issues on the same record as plant hours and job cards. The ghost plant check then becomes a filter, not a hunt through paper.

Telematics is a useful cross-check, but older and hired plant often has none, so keep the slip. If your fuel records still sit in a head office spreadsheet, our Excel to civil construction software migration guide shows how to move them without losing history.

Still reconciling diesel from a slip book that lives in the site container? Sakha keeps cost control and an offline site diary in one cloud software built for South African civil contractors: see a product demo.

Can Civil Contractors Claim the SARS Diesel Refund?

In general, no: the SARS diesel refund does not cover construction, so never price a civil tender as if you will get it back. The refund applies only to primary activities in a closed list of sectors, such as farming, forestry and mining. Contractors working on mines should check their own case with a registered tax practitioner.

The SARS diesel refund scheme sits in Part 3 of Schedule No. 6 to the Customs and Excise Act, 1964. It refunds part of the fuel levy and Road Accident Fund levy, but only for primary activities in a closed list of sectors: farming, forestry and mining on land, plus certain offshore, harbour, rail and electricity generation uses. Construction is not on the list.

Contractors who work on mines should check their own case with a registered tax practitioner. This article is not tax advice.

It is still a useful model: SARS expects claimants to keep logbooks of diesel bought and used for five years. A civil site can hold itself to the same standard.

Which KPIs Show Fuel Is Under Control?

Track six numbers weekly, on one page per site, to see whether your fuel controls work. They are litres per hour per machine, litres per 100 km for trucks, stock variance, slip completeness, fuel cost per unit of work and idle ratio. Together they show both theft and waste early.

Litres per hour per fleet number, against that machine’s own baseline.
Litres per 100 km for trucks and bowsers.
Stock variance %: unexplained variance as a share of issues, against your tolerance.
Slip completeness: the share of issues with fleet number, SMR and both signatures. Aim for 100%.
Fuel cost per unit of work: rand per m³ moved or per metre of pipe laid, against the allowance in your rates. Use the measured quantities from your remeasurement by chainage, so the unit cost matches what you are paid for.
Idle ratio, where telematics exists: idle hours as a share of engine hours.

Frequently Asked Questions

What is fuel management in construction?

It is the set of physical and paper controls that track diesel from delivery, through storage, to each machine. Its job is to flag losses early.

How much diesel does an excavator use per hour?

A 20 to 22 tonne excavator uses about 12 to 18 litres per hour under mixed load, and a 30 to 35 tonne machine about 18 to 26. Build your own baseline per fleet number.

How do I detect diesel theft on a construction site?

Compare delivery dips with delivery notes, daily dips with book stock, and litres per machine with hours worked. A variance above tolerance points to theft or a mechanical fault.

Can civil contractors claim the SARS diesel refund?

In general, no. The refund covers a closed list of sectors, such as farming, forestry and mining. Construction is not one of them. Contractors who work on mines should check their case with a registered tax practitioner.

The Bottom Line

Fuel is one of the few plant costs you can control day by day. Lock and meter the tank, and make one person responsible for it. Never dispense without a numbered slip that carries the fleet number and hour meter reading. Reconcile stock daily, litres per hour weekly and cost per unit of work monthly. Treat every variance as a question that needs an answer this week. Price adjustment, where your contract has it, follows the price of diesel. Only your records protect the litres.

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