Trenching and backfilling are a part of almost any construction project, including installing drainage systems or just overall house building. But every scoop of dirt comes with a price tag, so these should be a part of your overall budget.
Trenching and backfilling will typically cost you around $5 to $12 per linear foot, depending on the project you’re doing, the length and depth of the trench, the soil type, and the obstructions you need to remove.
Here’s a more thorough discussion of the factors that can affect the cost of backfilling and trenching to help you come up with a more accurate budget for your construction project.
Factors That Can Influence the Cost of Trenching and Backfilling
Project Type
Drainage System
Trenching and backfilling for a drainage system can cost around $1,900 to $5,100, including labor, equipment, support materials, and cleanup. The cost can significantly change if you do trenching and backfilling on your own or hire a pro.
Drainage systems are quite huge, so trenching will take longer than usual. They’re also often done in driveways, making trenching more challenging, as homeowners usually use hard and durable materials, like gravel and cement, for their driveways.
Electrical Panel
When installed underground, electrical panels are typically more protected against physical damage and environmental elements. However, underground electrical panels will require trenching and backfilling, driving up the total installation cost.
Underground electrical panels can typically cost around $600 to $2,100, depending on the size of the trench. You can dig the trench on your own, but you will still need to hire an electrician to do the installation, so the cost may still exceed $2,100.
Sewage System
Sewage systems are typically installed underground to prevent contaminating the surface water soil with pathogens and pollutants. Burying them also helps control the smell of wastewater, making the living experience more comfortable for homeowners.
Prepare about $1,400 to $4,600 for a sewage system installation. It’s a bit more costly than other home projects because the installation process is more complicated, as installers need to connect your pipes to the city’s sewage system.
Water Lines
Trenching and backfilling for water lines can cost anywhere between $600 and $2,100, including the materials and installation of new pipes. This is one of the projects that’s better left to the hands of professional plumbers to avoid paying more due to damages.
The total cost will still depend on the size of the trench and the type of pipe you use. Copper pipes are typically more durable compared to plastic ones, but expect to pay an extra $10 to $20 per linear foot, as they are a bit more expensive.
Foundation
A foundation project usually costs around $4,300 to $13,300, including trenching and backfilling, cleanup, and foundation materials. The final cost will depend highly on the terrain, soil type, and foundation type used for the foundation.
Monolithic slab foundations typically cost the cheapest, around $5 to $16 per square foot.
On the other hand, basement foundations are typically the most expensive, as they need extensive trenching and backfilling. Prepare about $18 to $37 per square foot for basement foundations.
Retaining Wall
Retaining walls are designed to hold back soil and prevent erosion, especially on sloped terrain. Trenching and backfilling will help create a stable foundation for the wall, so it’s a crucial part of the construction process.
Installing retaining walls can cost you around $2,900 to $7,800, including trenching, backfilling, labor, and materials. This can be a DIY project, so you can significantly lower the cost by trenching and backfilling the site yourself.
HVAC System
Some HVAC components, like piping, ductwork, and geothermal heat pumps, are sometimes installed underground to enhance energy efficiency, protect them from environmental elements, and make more efficient use of space.
Underground installation of some HVAC components can cost you more money due to trenching and backfilling. Generally, you have to prepare $3,800 to $7,200 for the overall HVAC installation, including trenching and backfilling.
Gas Line
Installing gas lines can cost you around $300 to $800, including trenching, backfilling, labor, and the materials used. The cost can vary depending on how far the main gas supply is and how extensive the trenching will be needed.
Gas lines are better protected from physical damage and potential accidents when buried, so it’s common that they’re installed underground.
However, it’s crucial that the lines are properly installed to avoid leaks, so it’s always best to hire a pro to do the work.
Trenching Method
Hand Trenching
Hand trenching involves manually digging a trench using tools like shovels, spades, and picks. This is a labor-intensive method and takes quite some time to do, so it’s only suitable for small-scale projects that don’t need deep trenches.
Expect to pay around $5 to $11 per linear foot if you’re hiring someone to dig and backfill a trench by hand.
Machine Trenching
Machine trenching can cost you around $13 to $24 per linear foot, including backfill material. It generally costs more than hand trenching since you need to account for the rent of the equipment and the cost of hiring someone to operate the machinery.
Machinery trenching is often done for large-scale projects since employing machinery, like backhoes and trenchers, is more efficient.
Size and Depth of Trench
The size and depth of the trench will generally determine how much labor is needed, how much time it will take to do the job, and what kind of trenching method is needed, so they significantly affect the total cost of trenching and backfilling.
Larger and deeper trenches will generally need more excavation work, so they’re often done through machine trenching, which usually costs more. Even when done through hand trenching, they can be costly since labor costs will be much higher.
They also require more backfill material to cover and stabilize the installed utilities or structures, which will further drive up costs.
Labor
The total labor cost will vary depending on the type of worker you hire. Laborers who will do hand trenching typically don’t charge as high as landscapers and machine operators, but they can still be costly since they’ll work longer.
Laborers usually charge $35 to $65 per hour for trenching and backfilling, while landscapers charge $50 to $100 per hour. Rates of skilled operators vary greatly depending on the type of machine they’re operating and their company.
You’ll also need to hire a different professional to install the utilities or structures you need. Plumbers generally charge $45 to $150 per hour, while electricians charge $50 to $130.
Soil Type
Soil type can have a substantial impact on the total cost of trenching and backfilling in construction projects. This is because it typically determines how complex and challenging the overall trenching and backfilling process will be.
Rocky soil typically requires more powerful excavation equipment, such as rock trenchers or hydraulic breakers, so they can be more costly. Clay soils, on the other hand, tend to stick to the equipment, making them harder to remove.
Trenching and backfilling rocky or clay soil can cost $200 to $1,200 more than soft and loose soil. The cost can go much higher if the land is also steep or sloped, as operating machinery in these types of lands can be more challenging.
Additional Costs That May Be Incurred
Permits
Local authorities generally require property owners to get permits before trenching and backfilling. This is to help them regulate and monitor the trenching process, which is necessary to protect the safety of the city’s residents.
They typically charge fees to process permit applications, which can go from $50 to $400. Some may even go as high as $2,000, depending on the type of project you’re doing.
Site Preparation
If access to the site is obstructed, whether by trees or large boulders, you’ll have to pay an additional $50 to $2,000 to remove them. The cost will depend highly on the type and size of the obstruction workers need to remove.
Removing a whole tree can cost you around $300 to $2,000, while a tree stump can cost anywhere between $100 and $400. The larger and older the trees are, the larger the roots are, so the cost will also be higher.
On the other hand, large boulders or ledge rocks removal will cost $50 to $250 per cubic foot.
How much does it cost to dig and backfill a trench by yourself?
Trenching and backfilling a trench by yourself can help you save up on labor costs but will take up a lot of your time. The only cost you’ll have to pay when doing the work yourself is machine rent and the tools you’ll need.
Prepare about $125 per day to rent a micro-trencher and $12 to $100 to buy shovels and spades. You may also have to pay for backfilling materials, which can cost you around $5 to $25 per cubic yard.
Overall, you can expect to pay a minimum of $142 for a 2-foot wide and 2-foot deep trench if you dig it yourself.
While you can do trenching by yourself, it’s generally advisable to leave the installation process of the utilities or structures to professionals. This can help you prevent paying for additional costs due to improper installation.
How do I save money when digging and backfilling a trench?
- Do the trenching by yourself.
Trenching can be an easy DIY task if you have the time and tools needed. By doing the trenching on your own, you’ll only have to pay for the installation of the utilities, significantly decreasing the total project cost.
- DIY site preparation.
If the trees, rocks, or any site obstructions aren’t too big, you can probably do site preparation on your own. This can help you reduce the total cost of the project.
- Rent equipment instead of purchasing them.
Machines, such as trenchers, can be very expensive. Some people rent out machines, so you can save up by renting theirs instead of buying your own.
- Compare multiple quotes.
If you can’t do the job yourself, contact multiple contractors and get quotes from each. This will help you get the most competitive deal for your budget.
- Reuse on-site material.
If possible, reuse the excavated soil as a backfill to avoid spending more on backfill material. This will also help you save on waste disposal and cleanup.
