Directional Drilling

# How Contractors Avoid Hitting Existing Utilities

TLDR

Utility strikes are prevented by **Sunshine 811** tickets, positive response review, **vacuum potholing** at every crossing, and tracking the drill head against **verified depths**, not assumed ones.

Last updated October 20, 202613 min read

Contractors avoid strikes by filing a Sunshine 811 ticket, waiting the required notice period, reviewing positive response from every member operator, exposing each marked line by vacuum excavation before boring past it, and tracking the drill head continuously against those measured depths. Marks show approximate horizontal position only, so daylighting is the step that actually prevents damage.

## Why do locate marks alone not prevent strikes?

A locate mark tells you approximately where a facility sits horizontally. It does not tell you how deep it is, how many lines share the same trench, whether the line was relocated after the record was drawn, or whether it belongs to the large category of facilities nobody is obligated to mark.

That is why damage prevention law defines a tolerance zone around the mark rather than treating the paint line as an exact position, and why excavation inside that zone has to be performed in a way that will not damage the facility. On a directional bore the crossing is invisible from the surface, so the only reliable way to know clearance is to have physically seen the utility first.

Every serious damage prevention program is built on that one idea: marks locate, potholes verify.

## How does the Sunshine 811 process work in Florida?

Florida's one call system is Sunshine 811. Before excavation, and directional boring counts as excavation, the contractor files a locate ticket describing the work area. Member utility operators then respond within the statutory notice period, either by marking their facilities or by reporting that they have none in the described area.

Positive response is the part crews skip at their peril. Every member operator on the ticket is expected to respond, and the ticket is not complete until each one has. A site with paint on the ground and one missing response is a site with an unlocated facility on it.

Tickets have a life. They expire, and marks fade or get destroyed by weather, traffic, and other contractors long before the paperwork does. Work that runs long needs the ticket refreshed rather than relying on old paint. Emergency tickets exist for genuine emergencies such as an outage or a hazard, and they carry a shorter notice period, not a lower standard of care.

Not everything on a site is a member facility. Private lines beyond the meter, site lighting, irrigation, septic systems, pool equipment, and older customer owned services are typically the property owner's responsibility, and a private locate is arranged separately.

## What do the marking colors mean?

Florida uses the APWA uniform color code, and reading it correctly matters because the response to a marked line depends on what is in it.

| Color | Facility type |
| --- | --- |
| Red | Electric power lines, cables, conduit, and lighting cables |
| Yellow | Gas, oil, steam, petroleum, and other flammable material |
| Orange | Communications, alarm and signal lines, cable, and conduit |
| Blue | Potable water |
| Purple | Reclaimed water, irrigation, and slurry lines |
| Green | Sewers and drain lines |
| Pink | Temporary survey markings |
| White | Proposed excavation route or limits |

## What does potholing do that nothing else can?

Potholing, also called daylighting, exposes the facility so it can be measured. Vacuum excavation is the standard method because air or water lances loosen soil without the mechanical force that damages coatings, conduit, or direct buried cable.

The measurement is the deliverable. Record depth to the top of the facility, horizontal offset from a fixed reference such as edge of pavement or a property corner, the size and material, and the station along the bore alignment. Photograph it with the tape in the frame so the number can be defended later.

Those numbers then go onto the bore profile. A crossing plotted at a measured depth is something the drill operator can steer to. A crossing that exists only as a paint line and an assumption is not a control point, it is a hazard the crew is hoping to miss.

## What are utility quality levels, and why do they matter on a bore?

Engineers grade how far they trust utility information using the quality levels in ASCE 38, the standard guideline for investigating and documenting existing utilities. The levels run from D, the least reliable, to A, the most reliable. Knowing which level a drawing reflects tells the bore crew how much verification is still needed.

Quality level D comes from records and recollection. Level C adds a survey of visible surface features such as valve boxes and pedestals. Level B uses geophysical methods, such as electromagnetic locating and ground penetrating radar, to mark horizontal position on the ground. Level A comes from test holes that expose the facility and measure its depth, size, and material.

Most utility lines on a set of plans sit at level C or D unless the project paid for more. A bore profile drawn around level D information is drawn around guesses, which is why potholing at each crossing converts the critical points to level A before the drill head gets near them.

## How should the bore profile be designed around crossings?

The profile is designed backward from the crossings, not forward from the entry pit. Each verified utility becomes a fixed control point with a required separation, and the path is drawn to clear all of them while staying inside cover requirements at the surface.

Separation requirements arrive from several directions at once: the facility owner's construction standards, the right of way permit conditions, and applicable code. When they conflict, the most restrictive governs, and that determination belongs in planning rather than in a conversation with an inspector after the fact.

- Cross under existing facilities where practical, so the bore stays below the known line.
- Cross as close to perpendicular as the site allows, which shortens the distance the head travels inside the tolerance zone.
- Keep steering changes away from the crossing itself, arriving on a steady pitch and roll so position is predictable.
- Set entry angle and depth so required separation is achieved well before the crossing, not at it.
- Identify no-drill zones where separation cannot be met, and resolve them by design change or open cut before mobilizing.

## How does tracking during the bore keep it honest?

Approaching a crossing, the tracking interval tightens. Instead of one reading per rod, the operator tracks in partial rod increments so head position is known before it enters the tolerance zone rather than after it has passed through.

A spotter stands over the crossing with the utility marked and, where practical, exposed. Vacuum potholes are frequently left open and protected for exactly this reason: the crew can see the facility and can see fluid movement or ground disturbance the instant something goes wrong.

If the locate signal degrades near the crossing, the correct move is to stop advancing. Interference is common near metallic facilities and near power, and a degraded reading at the one place accuracy matters most is a reason to back off, re-verify, and change frequency or method before continuing.

## What about the utilities nobody marked?

Unmarked and abandoned facilities cause a meaningful share of damages. Abandoned lines are often unlocatable, nonconductive lines such as older plastic water and sewer without tracer wire may not respond to conventional locating, and service drops running from a main to a building are frequently missed entirely.

The countermeasure is investigation rather than optimism. The site itself usually tells you most of what the records left out.

- Ask the property owner and site manager what was installed, and when.
- Request as-builts from the facility owner and the local utility department, and treat them as a lead rather than a fact.
- Read the surface: meters, pedestals, valve boxes, cleanouts, risers, patched pavement, and settlement lines all point at something buried.
- Use ground penetrating radar where soil and target make it viable, understanding that saturated clay limits what it can see.
- Pothole anything the evidence suggests, even when nobody marked it.

## What makes locating harder in Central Florida?

Many Central Florida corridors carry a dense mix of older and newer facilities: plastic water and gas services, fiber in non metallic duct, and irrigation that property owners installed without records. A non conductive line can only be located electronically if a tracer wire or marker was installed with it and still works.

Ground conditions add their own limits. Ground penetrating radar loses depth in saturated or clay rich soil, and shallow groundwater fills pothole excavations quickly, which makes clean depth measurements harder to take. Crews plan for dewatering at potholes and photograph the measurement before the hole floods.

Growth adds churn. In fast developing parts of the region, new subdivisions and road widenings relocate utilities faster than records are updated, so as-built drawings only a few years old can already be out of date. On those corridors, the safe assumption is that records are leads to verify, not answers.

## What happens if a line is hit?

The sequence is fixed and does not include improvisation. Stop work and secure the area. If gas is involved, evacuate, keep ignition sources away, and call 911 before anything else. Notify the facility owner and Sunshine 811, and do not attempt repairs on someone else's facility.

Then document: photographs of the marks, the pothole, the equipment position, the ticket, and the damage itself, along with the names of everyone on site. That record determines responsibility later, and it protects a contractor who followed the process as much as it exposes one who did not.

The most useful outcome of a damage or a near miss is a changed practice. A pattern of surprises along one corridor almost always means the records are wrong, and the correct response is more potholing rather than more caution at the same level of information.

## What documentation proves damage prevention was done?

The closeout file should let someone reconstruct the crew's decisions months later, which is exactly what happens when a claim, a redesign, or a future project touches the same corridor.

Strilla Communications assembles this file as the work proceeds rather than at the end, because most of these measurements only exist while the hole is open and the utility is exposed.

- Ticket numbers, ticket dates, and positive response records covering the work window.
- Dated photographs of marks before work started.
- Pothole log: station, facility type, size, measured depth, offset, and photograph.
- Bore profile showing planned and achieved separation at every crossing.
- Daily production reports noting crossings completed and any anomalies.
- As-built with installed path, depth, and tracer wire terminations.
- Restoration photographs and permit closeout correspondence.

## Key takeaways

- Locate marks show approximate horizontal position only, and they never show depth.
- Potholing at every crossing turns a marked utility into a measured control point the drill operator can steer around.
- A Sunshine 811 ticket is not complete until every member operator has posted a positive response.
- Private lines such as irrigation, site lighting, and customer owned services are not marked by member operators and need a separate locate.
- A bore profile should be designed backward from verified crossings, not forward from the entry pit.

## Key terms

**Sunshine 811**: Florida's one call notification center. Excavators, including directional boring crews, file a locate ticket before digging, and the center notifies member utility operators, who then mark their facilities or report that they have none in the described work area.

**Positive response**: The reply each member operator posts to a locate ticket, stating that its facilities are marked, that it has none in the area, or that another condition applies. Excavators check every response before starting work rather than relying on paint alone.

**Tolerance zone**: The protected strip on both sides of a marked underground facility, defined in Florida's damage prevention statute, Chapter 556. Excavation inside it must use methods that will not damage the facility, such as hand digging or vacuum excavation, and a bore crossing it needs verified depth.

**Vacuum excavation**: Digging a test hole with an air or water lance to break up the soil and a vacuum hose to lift it out. Because no bucket touches the facility, the crew can expose a marked line, measure its depth and size, and photograph it without damaging the coating or duct.

**Subsurface utility engineering**: An engineering practice for locating, mapping, and documenting existing utilities during design. It grades utility information by quality level, from records alone up to test holes that physically expose and measure each facility, so designers know how far to trust a drawing.

*ASCE 38 utility quality levels on a bore project*

| Quality level | How the information is obtained | What it can be trusted for | Role on a bore |
| --- | --- | --- | --- |
| Level D | Records, maps, and recollection | Knowing a utility probably exists in the area | Starting point only, never a control point |
| Level C | Surveyed surface features matched to records | Approximate alignment between visible features | Shows where to locate and pothole |
| Level B | Geophysical designating such as EM locating and GPR | Horizontal position marked on the ground | Sets alignment, but depth is still unverified |
| Level A | Test holes that expose the facility | Measured position, depth, size, and material | The only level fit to steer a bore past |

*Depth of cover and utility clearance*

## What this means for your project

A utility strike is one of the few construction events that can turn a routine bore into a safety incident, an outage for other customers, and a liability claim on the same afternoon. The controls that prevent it are inexpensive compared with any one of those outcomes: tickets, positive response checks, potholing, and tight tracking at crossings.

Build potholing into the schedule and the price from the start. Treating it as an optional line item invites pressure to skip holes when the job runs behind, which is exactly when mistakes happen. If design drawings show utility information at quality level C or D, expect the crew to pothole every crossing and budget the time to do it.

Ask for damage prevention records in the closeout: ticket numbers and positive responses, photographs of marks, the pothole log with measured depths, and achieved separation on the profile. If a facility owner questions the work later, that file is the evidence that the standard of care was met.

## Related reading

- [Utility crossing boresPlanning and drilling past existing facilities with verified separation.](https://strillacommunications.com/services/directional-drilling/utility-crossings)
- [Road crossingsBores under city, county, and state roads, where utility density is often highest.](https://strillacommunications.com/services/directional-drilling/road-crossings)
- [Locate and repairFinding and fixing buried plant when something does go wrong.](https://strillacommunications.com/services/system-maintenance/locate-and-repair)
- [Field safety practicesHow crews protect people and facilities on outside plant jobs.](https://strillacommunications.com/resources/safety-practices)
- [Making fiber findable with tracer wireWhy non metallic pathways need a conductor to be marked on future tickets.](https://strillacommunications.com/blog/what-tracer-wire-does-in-fiber-installations)
- [Pre-construction planningLocates, walkouts, and bore planning done before mobilization.](https://strillacommunications.com/about/our-process/pre-construction)

## Frequently Asked Questions

**How long is a Sunshine 811 ticket good for?**: Tickets have a defined life set by Florida statute, and marks degrade well before the paperwork does. The practical rule is to refresh before expiration and any time marks become unreadable, are destroyed by weather or traffic, or the work area changes. A remark request costs a phone call. A damaged fiber trunk does not.

**Does calling 811 transfer liability?**: No. The ticket is a required step, not a shield. Florida's damage prevention law also requires excavating with care inside the tolerance zone, which for a bore means verifying facility depth and position before crossing. A contractor who filed a ticket, ignored a missing positive response, and bored blind through a marked corridor has not met the standard of care.

**How many potholes does a bore need?**: One at every crossing as a starting point, plus additional holes wherever a facility runs parallel and close to the alignment, or wherever records conflict with the marks. Long parallel runs sometimes need several to establish the actual line and grade of the existing facility. The count is driven by the crossings, not by a budget line.

**What if a utility owner does not respond to the ticket?**: Do not start. An unanswered ticket means one operator's facilities are unaccounted for, and the correct action is to follow up through Sunshine 811 rather than assume that no paint means no line. Document the follow-up, hold the work until the response is closed out, and note the delay in the daily report.

**Does directional boring need a Sunshine 811 ticket like trenching does?**: Yes. Florida's damage prevention law treats boring as excavation, so a directional bore needs a valid locate ticket before work starts, the same as a trench or a pothole. The ticket covers the full work area, including entry and exit pits, the alignment between them, and any staging excavation. Crews also confirm positive response from every listed operator before the first rod goes in.

**How deep are existing utilities usually buried?**: There is no depth you can safely assume. Installation standards vary by owner and by era, and grade changes, road widenings, and landscaping alter cover after installation. A line placed at a standard depth decades ago may now sit much shallower or deeper than the record suggests. That uncertainty is the reason crews measure depth by potholing at each crossing instead of relying on typical values.

**Can a bore pass close to a gas main?**: Yes, when the separation required by the gas operator and the permit is verified and held. Crews expose the main by vacuum excavation, measure its depth, design the profile to clear it, and track closely through the crossing. Some operators require their own representative on site during the crossing. Any doubt about position or signal quality is a reason to stop and re-verify before continuing.

## Related services

- [Utility CrossingsBores crossing gas, water, sewer, and electric in Florida. Conflicts exposed and measured, clearances held to owner spec, cross bore risk controlled.](https://strillacommunications.com/services/directional-drilling/utility-crossings)
- [Bore Path PlanningBore path planning for Florida HDD projects: alignment, depth profile, entry and exit points, utility clearance, and bend radius checked before mobilizing.](https://strillacommunications.com/services/directional-drilling/bore-path-planning)
- [Road CrossingsPermitted road crossing bores in Volusia County and Central Florida. FDOT, county, and city right of way, traffic control, verified cover, restored shoulders.](https://strillacommunications.com/services/directional-drilling/road-crossings)
- [Directional DrillingTrenchless directional drilling for fiber and utility conduit across Volusia County and Central Florida, planned against verified locates and closed out with documented bore logs.](https://strillacommunications.com/services/directional-drilling)
- [As-Built DocumentationAccurate as-built records captured in the field during construction, not reconstructed afterward. Coordinates, depths, photos and reconciled footage.](https://strillacommunications.com/services/supporting-services/as-built-documentation)

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Source: https://strillacommunications.com/blog/how-contractors-avoid-hitting-existing-utilities