Survey Audit: When to Commission One

Survey audit requests usually arrive after a run of disputes over the numbers, when someone suggests that an independent view might settle things. An independent audit is sometimes the right answer, but a narrower check survey often answers the actual question faster.

This article helps you decide between the two. Comparing quotations once you have decided is covered in our article on survey quotation requirements.

When a survey audit is warranted

A survey audit is warranted when the doubt is about the survey work as a whole, rather than about a single figure that can be tested on its own.

Neither column is a judgement on the surveyor. A check survey tests a result. An audit tests the system that produces results.

Two rows in the table cause most of the hesitation. The first is repeated disputes with one contractor. Each dispute on its own may look like a single quantity, and each can be settled with a check survey. When the same kind of dispute keeps returning, though, the cause is more likely to sit in the control, the method or the records than in any one figure. Settling disputes one at a time then costs more than finding the cause once.

The second is a change of ownership or operator. A buyer inherits the control network, the plans and the survey records, and every future result will be built on them. A check of one quantity says little about that inheritance. An audit at handover records the state of the survey work on the day responsibility changes, which also protects the party handing it over.

What an audit examines that a check survey does not

An audit examines the control, the observations, the records and the working procedures, because a problem in any one of them affects every result built on it.

It observes independently rather than reviewing the original surveyor's calculations. Reviewing the arithmetic confirms only that the arithmetic was consistent. It does not detect an error in the observations it was based on. Where control is in doubt, an audit re-establishes it from an independent origin, such as national trigonometrical beacons where they are available.

On the Gem Diamonds Ghaghoo mine in Botswana, a complete mine audit re-established control from national beacons, generated new plans and a reporting system, and trained local surveyors to competency. For Mopani Copper Mines in Zambia, Survey House carried out check surveys across multiple shafts and an independent audit of all project contractors on Mopani's behalf.

Preparing for an audit

An audit runs faster and reports more clearly when the party commissioning it has the records and the access ready before the auditor arrives.

Gather the records

Collect the control listing, the plans and the survey records for the period in question. The evidence described in our survey handover checklist is the starting point.

Agree access

The auditor needs access to site, and usually to the original surveyor's data. Agree both in writing before the work starts, especially where the outcome may be contested.

Define the period and the scope

State what is to be examined and over what period. On volumetric work, that may be a run of month-end surveys. Underground, it may be the control network across a set of mine levels.

Where survey cannot help you

A survey audit establishes the state of the survey work, but some questions in a dispute sit outside what any audit can answer.

An audit reports the work at the time of the audit. It is not a warranty of work performed afterwards. It cannot measure ground that has since been mined out or covered, and it cannot decide a commercial dispute on the parties' behalf. Where access or programme limits the audit, those limits belong in the report. Mine survey practice in South Africa has its own professional body, the Institute of Mine Surveyors of Southern Africa. Before appointing an auditor, our guide on choosing a survey company sets out the questions worth asking.