The Invisible Technical
Debt of Brownfield
Projects

A level of complexity that is often underestimated

Brownfield projects — whether involving the modernization, expansion, or rehabilitation of existing facilities — are often approached as conventional projects with a few additional constraints related to the existing installation.

The reality is different.

Industrial facilities evolve over time: equipment is replaced, pipelines are rerouted, supports are modified, connections are added, and temporary solutions gradually become permanent. However, these changes are not always accurately reflected in drawings, 3D models, P&IDs, or technical databases.

A growing gap then develops between the installation as it is documented — the as-designed condition — and its physical reality — the as-built condition.

This gap represents a form of invisible technical debt. As long as no new project affects the installation, it may remain unnoticed. It becomes apparent during engineering, prefabrication, or construction, when information previously considered reliable proves to be incomplete, outdated, or incorrect.

How does this technical debt accumulate?

Brownfield technical debt rarely results from a single error. It develops progressively through the accumulation of local decisions, undocumented modifications, and fragmented information.

Several recurring causes can be identified.

Fragmented documentation

Technical information is often distributed across several departments, formats, and time periods: paper drawings, DWG files, 3D models, Excel spreadsheets, vendor documentation, maintenance reports, or knowledge held only by certain employees.

Each source may be partially accurate, while none provides a complete representation of the current installation.

Modifications made under operational pressure

On an operating site, the immediate priority is often to restore production or respond quickly to an operational requirement. Some modifications are therefore implemented locally without a complete update of the related documentation.

These adaptations may have been technically justified when they were made, but they become a source of uncertainty for future projects.

Insufficient change governance

When responsibilities for updating technical information are not clearly defined, information can be lost between engineering, construction, maintenance, production, and suppliers.

The physical modification is completed, but its documentary record remains incomplete or never reaches the installation's technical reference system.

Pressure on budgets and schedules

Site surveys, document audits, and the consolidation of existing information are sometimes viewed as preliminary costs that can be reduced.

However, these initial savings can generate far greater costs later: engineering rework, purchase-order changes, construction delays, additional site work, or the extension of an already constrained production shutdown.

The consequences emerge late

Technical debt is difficult to detect during the early stages of a project. It becomes visible when engineering reaches a more advanced level of detail — or, in the worst case, during installation.

Its consequences can then be significant:

• inability to connect a new line at the planned location;

• clashes with existing structures, equipment, or networks;

• actual dimensions or elevations differing from those shown on the drawings;

• missing, relocated, or inadequate supports;

• insufficient access for operation and maintenance;

• purchased materials that are incompatible with actual site conditions;

• prefabricated assemblies requiring modification;

• additional work during an already restricted shutdown window.

The issue therefore extends far beyond drawing quality. It directly affects safety, budget, schedule, production continuity, and the company's ability to develop and adapt its industrial assets.

Establishing a reliable baseline before designing

Managing a brownfield project begins with establishing a sufficiently reliable reference base to support sound decisions.

This does not necessarily mean surveying an entire site to the same level of detail. The objective is to identify the areas, interfaces, and equipment that are critical to the project scope.

This approach may combine:

• a critical review of the available documentation;

• field surveys and on-site verification;

• 3D scanning of the relevant areas;

• comparison between drawings, models, and physical reality;

• identification of interfaces and tie-in points;

• classification of information as confirmed, uncertain, or missing;

• centralization of discrepancies in a shared register.

The value of 3D scanning does not lie solely in producing a point cloud. Its real value comes from integrating it into a control process that compares, verifies, and improves the reliability of the data used by engineering teams.

Managing technical debt throughout the project

An initial audit is essential, but it is not sufficient. Discrepancies, assumptions, and missing information must remain visible throughout the project lifecycle.

Effective management should include:

• a register of uncertainties and identified discrepancies;

• a criticality level assigned to each issue;

• a designated owner and resolution deadline;

• design reviews at key project stages;

• a formal change-control process;

• progressive updating of the as-built documentation;

• budget and schedule contingencies proportionate to the identified risks.

This organization prevents an unverified assumption from gradually being treated as confirmed information and then passed on to engineering, procurement, prefabrication, and construction teams.

Turning the site's history into an asset

Technical debt within existing facilities is not inevitable. It becomes dangerous when it remains invisible, unassessed, or excluded from project decisions.

A well-prepared brownfield project does not attempt to eliminate every uncertainty before engineering begins. Its objective is to identify critical uncertainties, monitor them, and resolve them before they create irreversible consequences.

Field surveys, 3D modelling, document governance, and continuous discrepancy monitoring are therefore not merely preliminary tasks. Together, they form a genuine project risk-control system.

When knowledge of an installation is structured, verified, and continuously updated, it ceases to be a burdensome legacy. It becomes an industrial asset — one that enables more accurate engineering, reduces unexpected events, and secures the facility's future transformation.