Trenching Vs. Boring to Install Underground Utilities

Pros & Cons of Trenching

Advantages of Trenching

Trenching involves excavating long, narrow trenches to make way for utility lines like gas, electricity, cable, sewer, and more. Contractors use special equipment, like backhoes, excavators, and gas-powered trenchers to carve out pathways.

The main advantage of traditional trenching is its lower cost, provided your property doesn’t have large obstructions. Trenching costs $25–$100 per linear foot on average, while boring costs $30–$200 per linear foot on average.

Trenching is the only option if you live in a state requiring a sand layer beneath buried gas lines. In addition, trenching gives contractors full visual access to the work area, allowing for easier utility line installation than boring or blind drilling.

Disadvantages of Trenching

While traditional trenching is less expensive and more straightforward for open properties, it has some significant limitations

Costs can skyrocket if you have asphalt, concrete, or large boulders that need to be removed beforehand. Removal and replacement of concrete alone can add $25–$50 per square foot. Trenching through hard materials like solid rock using hydraulic breakers or other equipment can be extremely challenging and expensive.

Heavy rains make trenching nearly impossible due to mud and flooding in the trenches, forcing delays. 

Trenching under streams, ponds, or wetlands is typically not suitable because it disrupts delicate ecosystems. Directional boring is required instead. Trenching risks groundwater pollution if fuel, oil, or other chemicals spill into trenches, which can lead to environmental fines.

Trenching carries a higher risk of striking and damaging existing utility lines during digging than boring. The digging process disturbs the surface landscape and can harm tree root systems and underground ecosystems. 

Open trenches can be hazardous if not maintained properly. There are dozens of trench-related fatalities every year, posing a real threat to both workers and residents.

Pros & Cons of Boring

Advantages of Boring

Directional boring, or horizontal directional (HDD), installs underground utilities using specialized drilling equipment. With directional boring, contractors drill a series of boreholes along a planned route. Utility lines are then pulled through the holes, allowing for installation under obstructions. 

There are many advantages of directional boring compared to trenching.

Boring avoids demolition costs associated with trenching through concrete, asphalt, trees, and landscaping. Boring is better suited for properties with large boulders, hills, or steep slopes that would make trenching extremely difficult. The fluid nature of boring accepts variances. 

HDD drilling causes less surface disruption than trenches across a property. Lawns, gardens, and landscaping are mainly unaffected. Directional boring enables utility installation beneath trees, streams, ponds, and wetlands without environmental damage. Trenching is often not possible in these scenarios. 

The closed nature of boring eliminates vulnerabilities like cave-ins, flooding, and groundwater pollution associated with trenches.

Disadvantages of Boring

Directional boring is a more advanced, complex installation method than trenching. Directional boring equipment is very expensive, so boring usually costs considerably more than trenching. 

Severe soil conditions like solid rock can make drilling extremely difficult, limiting the effectiveness of directional boring. 

The drilling process requires more specialized operator training and experience than trenching. Improper boring technique risks utility damage or installation failure.

While less disruptive than trenching, boring equipment and staging areas still impact the surface to some degree. Note that grass and small plants may require re-seeding or planting after boring. 

Boring’s fluid drilling process and closed-off boreholes limit visual access to the work area, making utility installation more challenging than open trenching. Directional boring has a steeper learning curve for contractors than traditional excavation methods, so fewer companies offer the service.

Additional Factors Impacting Cost

The base costs of trenching versus boring provide a starting point for estimating utility installation costs. However, several other essential variables also affect the final price tag.

• Length of the utility line: Longer installations cost more overall, regardless of method.
• Soil conditions: Compact soil, clay, and solid rock make trenching and boring more difficult and expensive.
• Permit fees: Most localities require permits and inspections for underground utility work, adding $200–$500 to your total cost. Requirements vary by area.
• Utility type: Electrical and gas line installations are usually more complex and, therefore, more costly than water, sewer, or cable utilities.
• Timeframe: Expedited installation costs 25–50% more than standard turnaround. Unexpected delays also drive up costs.
• Property access: Difficult backyard access for equipment via narrow gates or lack of rear street access can hamper installation and increase costs.
• Restoration: Full pavement, concrete, and landscaping restoration add to the final costs. Basic lawn re-seeding is standard.

So, Is Trenching or Boring Better For Installing Underground Utilities?

Usually, traditional trenching is the more economical option for underground utility installation on open, obstruction-free properties. It causes more surface disruption than boring, but open access makes installation straightforward.

However, directional boring is worth the added cost for properties with extensive pavement, concrete, large boulders, steep slopes, or environmentally sensitive areas like wetlands. Boring also expands utility layout options by enabling installation under virtually any above-ground obstacle.

There are always exceptions based on unique property characteristics and cost differences between contractors. But in general, trenching is ideal for simple, low-cost installations on open land. Directional boring is preferable for obstacle-heavy or environmentally-sensitive properties despite higher costs.

You should consult multiple installation companies to get quotes on trenching and boring methods. Ultimately, the best technique for your underground utility installation comes down to your budget, yard layout, soil conditions, and utility requirements.