Subsurface Utility Mapping in North Georgia

“Serving the Greater Atlanta and Chattanooga Area and everything in between”

Preventing Catastrophic Utility Strikes During Excavation

Call 811 before you dig. Everyone knows the rule. But standard utility locates only show you part of what’s underground – and what they miss can cost you everything. 

A fiber optic line cut during excavation can bill at $92,000 for a single incident. A gas line strike can kill workers and destroy property.

Water main breaks flood sites and cost thousands per hour in lost water and emergency repairs.

Subsurface utility mapping goes beyond basic 811 locates to provide comprehensive documentation of what’s actually underground. 

It uses multiple technologies – ground-penetrating radar, electromagnetic locating, acoustic detection – to find utilities that free locating services miss.

It shows not just horizontal locations but depths. It documents private utilities that 811 doesn’t cover. It gives you certainty instead of assumptions.

Why Standard Utility Locates Aren’t Enough

The 811 system works through state-run notification centers. You call before digging, they notify utility companies, and utility companies send locators to mark their lines. 

It’s free, it’s required by law, and it prevents many utility strikes.

But it has limitations. Utility companies only locate their own lines – the ones they own and operate. 

Private utilities on your property don’t get located unless you hire private locators. Abandoned lines that are still live don’t always get marked. 

Service laterals from main lines to buildings may not be located in detail. And locators work from maps that aren’t always accurate or current.

The bigger problem: standard utility locates show horizontal position only. They paint marks on the ground showing where utilities cross your work area. 

They don’t tell you how deep those utilities are. If you’re excavating four feet deep and the utility is at six feet, you’re fine. If the utility is at three feet, you’re going to hit it.

Depth matters enormously. Shallow utilities get struck more often than deep ones. Utilities that aren’t where maps show them get struck. 

Utilities that cross paths with other utilities at different depths create confusion about which mark corresponds to which line.

The Real Costs of Utility Strikes

Fiber optic cables are expensive to repair. A cut to a residential drop line might cost $600-1,500 to fix. A cut to a commercial trunk line serving multiple businesses runs $10,000-25,000. 

A cut to a major telecommunications backbone can hit $92,000 for a single incident – the highest documented single fiber cut repair cost in 2019 industry data.

But direct repair costs are only part of the picture. 

The 2019 telecommunications industry reported $600 million in direct utility strike repair costs, but $18 billion in indirect costs – business interruption, emergency response, traffic delays, project delays, legal expenses, and insurance claims.

Gas line strikes are worse. Direct repair costs for gas line breaks range from $15,000 to $50,000 depending on line size and complexity. 

But gas leaks create immediate safety hazards. Sites get evacuated. Emergency responders arrive. 

Nearby buildings get cleared. If gas ignites, you’re looking at injuries, deaths, and property destruction that dwarf repair costs.

Water main breaks flood excavation sites and adjacent properties. Emergency water shutoffs affect entire neighborhoods. 

Repair requires digging up streets, coordinating with multiple agencies, and working under emergency conditions that drive costs higher. Water loss from major breaks runs thousands of dollars per hour even before repair work starts.

Sanitary sewer breaks create health hazards and environmental violations. 

Storm drain damage affects drainage systems. Electric line strikes shut down power and create fire risks. Each type of utility strike has consequences that extend far beyond the immediate repair.

The Four Quality Levels of SUE Work

The surveying industry defines four quality levels for subsurface utility engineering, labeled A through D with A being the most precise:

• • Quality Level D is existing utility records – maps and drawings from utility companies, as-built plans, government records. This is desktop research with no fieldwork. It’s the least reliable because records are often inaccurate, incomplete, or outdated.
  • Quality Level C is surveying visible utility features – manholes, valve boxes, meter locations, overhead lines – and correlating them to utility records. This improves accuracy but still doesn’t tell you what’s actually underground.
  • Quality Level B is surface geophysical methods – using ground-penetrating radar, electromagnetic locating, and acoustic detection to find utilities non-destructively. This shows what’s actually there, including lines not in records. It provides horizontal position and approximate depth.
  • Quality Level A is precise horizontal and vertical location through excavation – test holes that expose utilities so they can be measured exactly. This is the most accurate but also the most expensive and time-consuming. It’s typically used only for critical areas where absolute certainty is required.
  • Most subsurface utility mapping projects use Quality Level B throughout the site, with Quality Level A verification in areas where excavation will happen immediately adjacent to known utilities.

Technologies We Use to Find Underground Utilities

Ground-penetrating radar (GPR) sends radio waves into the ground and measures reflections from buried objects.

It works well in many soil types and can detect utilities made of any material – metal, plastic, concrete, clay. It shows utility depth more accurately than other methods.

GPR has limitations. It doesn’t work well in wet clay soils common in North Georgia. It requires interpretation – not every underground anomaly is a utility. 

It works better on some materials than others. But it’s one of the most powerful tools for finding utilities that other methods miss.

Electromagnetic (EM) locating works by detecting electromagnetic fields from utilities. 

Passive EM locating picks up fields generated by power lines or induced in metal pipes. Active EM locating applies a signal to a utility and traces that signal – useful for water lines, gas lines, and telecom conduits.

EM locating only works on conductive materials. It finds metal pipes and conduits but may miss plastic water lines, PVC sewer pipes, or concrete storm drains.

 It’s highly effective for what it finds but doesn’t locate everything.

Acoustic detection uses sound to find water leaks, air leaks in pressurized lines, or tracer gases injected into pipes. 

It’s a specialized technique used primarily for leak detection but sometimes helps locate pipes that other methods can’t find.

GPS and surveying equipment ties utility locations to property coordinates. Once we find utilities in the field, we need to map them accurately so engineers can design around them. 

Everything gets referenced to the same coordinate system used for site surveys and engineering plans.

What Subsurface Utility Mapping Shows

The deliverable from SUE work is a detailed map showing utility locations, depths, sizes (when determinable), types (water, sewer, gas, electric, telecom), and confidence levels. 

Utilities are color-coded using industry standards – red for electric, yellow for gas, orange for telecom, blue for water, green for sewer.

We document how we located each utility – GPR, EM locating, records research, visual observation. 

We note confidence levels – high confidence for utilities located with multiple methods, medium confidence for utilities located with one method, low confidence for utilities shown on records but not verified in the field.

Conflicts between different utilities get highlighted. If a water line and gas line cross paths, we document which one is deeper. 

If utilities are clustered together in a narrow corridor, we show that congestion so excavation can be planned carefully.

Utilities that don’t appear on official records – abandoned lines, private lines, unrecorded installations – get flagged. 

These are often the most dangerous because nobody knows they’re there. Finding them before excavation starts prevents surprises and potentially catastrophic strikes.

Private Utilities the 811 System Doesn’t Cover

Private water lines from wells to buildings don’t get located by 811. Private sewer lines from buildings to septic systems or main sewers don’t get located. 

Irrigation systems, yard lighting, security systems, data cables between buildings, private fiber optic installations – none of these show up in 811 locates.

On commercial and industrial properties, the proportion of private utilities can be substantial. A manufacturing facility might have extensive underground utilities – process piping, compressed air lines, chemical lines, fire suppression systems, backup power cables. 

None of these are public utilities and none get located by the free 811 service.

These private utilities are your responsibility to locate and protect. If you strike them during excavation, you pay for repairs. 

If they’re critical to operations and you knock them out, you’re paying for business interruption.

If they contain hazardous materials and you rupture them, you’re dealing with environmental contamination and regulatory penalties.

Professional subsurface utility mapping finds private utilities along with public ones. We use the same technologies to locate everything underground, giving you a complete picture of what you’re dealing with.

When You Need Subsurface Utility Mapping

Any project with excavation deeper than two feet should consider SUE work. Shallow digging for landscaping or fence posts carries less risk. 

Excavation for foundations, utilities, underground structures, or site grading puts you in the zone where utility strikes happen.

Large projects with extensive excavation need SUE for risk management. A $5 million construction project can’t afford delays from utility strikes. 

Spending $15,000 on comprehensive utility mapping is cheap insurance against $100,000 strikes.

Urban sites and developed areas have more underground utilities than rural sites. The more development that’s happened above ground, the more utilities are likely to be below ground. 

Sites that have been built on, demolished, and rebuilt multiple times have layers of utilities from different eras.

North Georgia sites with red clay soil benefit especially from GPR investigation. Clay holds moisture and can conduct electricity, making EM locating less effective. GPR works better in these conditions and provides better depth information.

Integration with Engineering Design

Subsurface utility mapping data integrates directly with engineering design. The utility map uses the same coordinate system as site surveys and engineering plans. 

Engineers import our utility data into their CAD software and design around known utility locations.

When engineers route new utilities, they can avoid conflicts with existing utilities. When they plan excavation, they know where utilities are and can specify safe clearances. 

When they prepare construction documents, they can note existing utilities that need protection or relocation.

This prevents conflicts during construction. Contractors know what’s underground before they mobilize equipment. They can plan excavation to avoid utilities or make arrangements to relocate utilities before excavation starts. 

They don’t encounter surprises that stop work and trigger change orders.

Cost Versus Risk Analysis

Subsurface utility mapping costs vary with site size and complexity. A small site might be a few thousand dollars, while a large complex site could be several tens of thousands of dollars. 

 These costs seem significant until you compare them to utility strike costs.

One fiber cut can exceed your entire SUE budget. 

One gas line strike definitely will. The decision isn’t whether you can afford SUE – it’s whether you can afford NOT to do it given what you’re risking.

Insurance often covers utility strike damage, but deductibles typically run $10,000-25,000 and your premiums go up after claims. 

Self-insuring by not doing SUE and accepting strike risk is expensive when strikes happen.

Many owners and contractors view SUE as optional nice-to-have information. It’s not. It’s risk management that prevents catastrophic failures. 

The question isn’t whether to do it – it’s how much detail you need based on project risk.

Due Diligence Requirements

Some lenders and insurance companies require subsurface utility mapping on larger projects. They’re protecting their investment and managing their risk exposure. 

If a utility strike shuts down your project for weeks and prevents loan repayment, the lender loses. If a gas line strike burns down adjacent buildings, insurance losses multiply.

Due diligence for property acquisitions increasingly includes SUE work. Buyers want to know what underground utilities exist, what condition they’re in, and whether they’ll support intended uses. 

Discovering after closing that the site lacks adequate utility capacity or that existing utilities need expensive replacement isn’t acceptable.

Environmental site assessments sometimes trigger utility investigation. 

If you’re buying property with contamination concerns, you need to know where underground utilities might provide pathways for contamination migration or might get damaged during remediation work.

What Happens When You Find Utilities

Finding utilities is the start, not the end. Once we map existing utilities, you need to plan around them.

 Sometimes that means adjusting building locations or excavation depths. Sometimes it means relocating utilities before construction starts. 

Sometimes it means special construction methods to protect utilities during excavation.

Relocating utilities takes time and money but prevents bigger problems. Moving a water line before excavation starts costs less than breaking it during excavation and dealing with emergency repairs.

Relocating a gas line before construction is cheaper than designing foundations around it.

Protecting utilities in place requires careful excavation methods. Hand digging near utilities. 

Using vacuum excavation instead of backhoes. Installing protective barriers. Monitoring during construction. All of this adds cost but prevents strikes.

The key is knowing early enough to plan properly. SUE work during design lets you address utility issues before construction bids go out. Finding utilities during construction creates emergencies and change orders.

Long-Term Value

The subsurface utility map you create for construction has value beyond the current project. When you want to expand, install new utilities, or make site changes later, you start with documented information about existing utilities. 

You’re not guessing or relying on old records.

When you sell property, providing utility documentation adds value. The next owner knows what utilities exist and where they are. 

They can plan development without starting utility investigation from scratch.

For facilities management, utility maps help with maintenance and emergency response. When a utility fails, you know where it is and how to access it. When you need to shut off utilities, you know where valves and controls are located.

Why This Matters

Subsurface utility mapping prevents disasters. It’s not about checking boxes or meeting minimum standards.

 It’s about not killing people, not destroying property, not bankrupting projects with catastrophic utility strikes.

The cost is manageable. The risk without it is unacceptable. That’s the calculation, and the answer is clear for any project with significant excavation.

The Land Surveying Company provides subsurface utility mapping services throughout Georgia, Tennessee, Alabama, and Kentucky. We use multiple technologies to locate underground utilities and provide comprehensive documentation for engineering and construction.

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