Excavation: what to know

What the job involves, what changes the price, and what to ask a pro.

What excavation is

Excavation digs and moves soil with machinery for foundations, trenches, pools, drainage lines and utilities, and it hauls off or reuses the dirt as planned. People call for it before a build or a repair, and the work has to start with locating buried lines because a single strike can stop a job and injure the crew.

Signs you need it

  • A new foundation, footing, pool, shed or addition needs the ground dug to a set depth before anything can be built
  • A drainage line, sewer line, water line or electrical run must be trenched in from the house to a new point
  • A stump, a buried tank, an old footing or a pile of fill sits in the path of the next project and has to come out
  • A yard or lot needs the topsoil removed and the subsoil dug out so a patio, slab or garden bed can be set
  • Water collects against the foundation, and the soil around it has to be dug out and rebuilt with proper slope
  • A utility company or a building project calls for trenching in a specific route, and the dirt must be handled to a plan

What the pro does

  • Have the buried utility lines marked through the utility locate service before any digging starts
  • Set stakes and mark the cut lines, depth and slope so the machine operator digs to the plan instead of by eye
  • Remove topsoil first and stockpile it separately, so it can be spread back on finished grades
  • Dig the subsoil to depth with an excavator or a loader, keeping trench walls sloped or braced where the depth requires it
  • Haul off the surplus material or grade it into place, compacting the fill in layers where it will carry a load
  • Check the bottom and the grades against the plan, then leave the site stable and free of open holes

What changes the price

Every job is different, so we do not publish prices. These are the things that move the quote up or down.

  • Volume of soil to move, and whether it is topsoil, clay, rock or mixed fill, since each digs at a different rate
  • Depth of the cut and whether the sides must be sloped back or braced to keep the trench safe
  • Distance to the haul-off site, and whether the spoil can be reused on the property or must be carried away
  • Access for the machine, including gates, slopes, trees and overhead lines that limit how the work can be done
  • Buried utilities, rock, roots or old foundations found during the dig, which slow the work and change the method
  • Compaction and fill needed afterward, such as engineered fill under a slab or a pad

What a written quote should spell out

  • The area, depth and volume of the excavation, with the method and equipment named
  • Utility locate and marking, and who is responsible for it
  • Topsoil handling, including whether it is stockpiled and respread
  • Haul-off or reuse plan for the spoil, with the destination if it leaves the site
  • Trench support or sloping details for any cut deeper than the site can safely stand
  • Backfill, compaction and grading of the excavated area, and the material used

Questions to ask before you hire

  • Have the buried lines been marked, and who called in the locate request?
  • How will you keep the trench walls safe, and do you slope them or brace them?
  • What do you do with the topsoil and the subsoil, and is hauling included?
  • What happens if you hit rock, roots or an old footing in the dig?
  • Will the excavation be backfilled and compacted, or left for the next crew?
  • How will you protect the house, the fence and the plants near the work?

Red flags

  • Starts digging without marking the buried utility lines in the work area
  • Leaves a deep trench open overnight with no barricade, sloping or support
  • Piles spoil right against the foundation or the edge of a trench
  • Says the soil will be fine to build on without a compaction plan for the fill
  • Quotes a dig by the machine hour without a plan for the depth, the haul and the grade

What you can do yourself

A homeowner can dig a shallow hole for a planter or a small garden bed by hand, after checking for buried lines in the area. Call a pro for any trench, deep dig, foundation cut, slope cut or dig near a utility line, since a collapsed trench can kill a person quickly. Keep out of any trench deeper than your knees, and do not stand near an unsupported cut wall.

Licenses and permits

Excavation is commonly done by licensed contractors, and digs for foundations, utilities and grading often need a permit in many areas. Check with your state or local licensing agency and your local building department before work starts, and confirm the utility locate rules that apply to the dig.

Excavation questions

Do I need the utility lines marked before digging?

Yes, and the marking should happen before any digging starts, even for a shallow dig. Buried gas, electric, water and sewer lines can be damaged by a shovel or a machine, so ask the pro to confirm the locate is complete.

Can I reuse the dirt I dig out?

Often yes, for topsoil in the yard or for fill in low spots, but subsoil and clay may not be suitable for every use. Ask the pro whether the spoil is reusable and where it will go if it is not.

Why does the trench need to be sloped or braced?

Deep trench walls can collapse without support, and that is one of the most dangerous conditions on a dig site. Ask the pro how they protect the trench walls for the depth you need.

About this guide

This national guide is written and checked by infinibell. Rules and conditions differ by place, so local pros are credited on guides for the cities they serve, not on national ones.

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