Historical Infrastructure May Not Be Documented

A significant reason why utilities are found in unexpected places is the age of the infrastructure. In many urban areas, especially older cities, there is a possibility that a survey may find pipes, sewers, or cables that were installed decades (or even a century) ago. These utilities might predate modern mapping systems, and their precise locations might never have been accurately documented. Over time, these forgotten or undocumented utilities can be buried under newer infrastructure, making their discovery surprising.

In older areas, it’s not uncommon for utility surveys to find discontinued gas lines, forgotten storm drains, or even old telephone cables that no one knew existed. This emphasises the importance of utility surveys, as construction teams often contend with decades of unrecorded infrastructure history.

Relocation of Utilities caused by Shifting Soil and Erosion
Natural events like soil erosion, flooding, or shifting land can cause utilities to move gradually over time. This is particularly common in areas prone to landslides, sinkholes, or even just gradual soil settling. What may have originally been a straightforward underground path for a water pipe might now weave unexpectedly through the soil. As a result, utilities may no longer be in the precise location indicated on older maps, creating confusion when workers rely solely on outdated documentation. Surveys uncover these shifts by preventing damage and costly repairs.

Unauthorised Modifications or Additions
Over time, property owners or contractors may have made unauthorised changes to utility lines. These can include rerouting water lines, add new drainage systems, or installing electrical cables without officially recording them, these changes can lead to utilities being in unexpected places. For example, a homeowner may have installed an extra pipe for drainage, or a contractor might have buried a power line in a less-than-ideal spot without proper permits or notification to the local utility company.  These unauthorised modifications are particularly common in private properties and areas where homeowners or builders attempted to cut costs or bypass regulations. A utility survey will reveal if there are any changes before, they cause problems.

Inconsistent Mapping Standards
Different utility companies often use inconsistent mapping standards and systems to log the location of their infrastructure. Some may use detailed geographic information system (GIS) data, while others rely on old paper records. Over the years, discrepancies between these records can arise, leading to utility lines being misplaced on maps or omitted entirely.

The lack of a unified system means that in some cases, multiple utilities (like water, gas, and telecommunications) may be inaccurately documented relative to one another. Surveyors can catch these discrepancies and prevent construction teams from accidentally hitting or damaging lines.

Urban Expansion and Changing Land Use
As urban areas evolve and cities continue to expand, roads become rerouted and old industrial sites have transformed into residential neighbourhoods. With urban development, the original placement of utilities may no longer align with current land use. Another contributing factor to finding utilities in unexpected places.

For instance, a road might have been widened, forcing utilities that were once under the pathway to now be beneath the road. Or an area that was once industrial might now be a commercial or residential zone, but the utilities from the previous infrastructure were never relocated or updated.

Utility Crossings and Overlaps
In dense urban areas or regions with a lot of infrastructure, multiple utility lines can cross and overlap with one another. This is usually more common in older cities with deep, layered infrastructure. For example, you might expect to find a simple sewer line a few feet beneath the surface, only to discover it tangled with fibre-optic cables or gas pipes running in unexpected directions. The overlapping of multiple systems in proximity creates a complex web of utilities that can be challenging to anticipate.

Advances in Survey Technology
While many unexpected utilities are the result of historical issues, advances in survey technology have also played a role in revealing more of what lies beneath our feet. Modern tools like ground-penetrating radar (GPR), electromagnetic locators, and drone mapping can detect utilities that older methods would have missed. These technologies can sense utilities deeper underground, locate plastic pipes, or find non-metallic cables that traditional equipment might not detect. This means that utility surveys today are far more comprehensive, often discovering unexpected lines or pipes that would have been overlooked in the past.

Summary
Utilities are an important element within modern infrastructure and can be found in some of the least expected places. Conducting a thorough utility survey before breaking ground is essential for safety, efficiency, and avoiding costly mistakes during construction.

Survey Manager Jack Matthews comments: “It just goes to show that no matter how clear you think an area is, having a utility survey undertaken is a necessity to ensure the safety of all workers on site and also to reduce costs on designs when an unexpected service shows up.”

Learn more about utility surveys by arranging a CPD with one of our Business Development Managers today.