Excavation for Foundations, Basements and Site Structures

Calling in the underground locates is the first excavation task on any Abilene job, and the one most often left too late. Before a bucket touches the ground we want the utility marks painted, the survey control checked and the geotechnical findings read, because the depth and shape of a hole depend on what is already under it and what the soil will tolerate. A clean excavation is the product of that preparation, not of operator speed.

We dig for foundations, equipment pits, elevator and dock pits, vaults, tanks and building pads, and we do it with the finished concrete in mind. A footing trench that is two inches too deep, a pit with a soft bottom or a sidewall that sloughs into the form line all cost the owner money later. Our process ties each excavation to the drawing that governs it, the inspection that will review it and the pour that will follow.

Locates, shoring and keeping people out of the hole

Excavation is one of the most regulated activities on a construction site, and we run it that way. A competent person classifies the soil, chooses sloping, benching, shields or shoring accordingly and inspects the excavation at the start of each shift and after rain. Ladders or ramps are placed so that nobody has to climb out over a spoil pile, and spoil and equipment stay back from the edge.

Underground hazards are handled by locates, potholing where marks are uncertain and hand digging near live lines. In a city that carries water, sewer and gas under many of its older streets, we assume nothing is where the drawing says until we have seen it. Our practice is described in more detail under utility potholing and locating.

Reading the ground and the surroundings

Clay over caliche is the typical Abilene profile, and it behaves differently from one season to the next. Dry clay stands steeply but can crack and drop slabs of material into the trench, and wet clay slumps and sticks to buckets. Caliche may be rippable in one place and need heavier equipment a few feet away, a topic we cover in rock and hard ground excavation.

The surroundings matter as much as the soil. Downtown Abilene sits north of the former Texas and Pacific tracks, now part of the Union Pacific mainline, while the growing SODA district lies south of them, and excavating in either area means working near rail, street frontages and older buildings. We check adjacent structures, survey any settlement concerns and plan spoil handling with the traffic and parking limits the city or owner imposes.

Buildings that call for deep and precise excavation

Hospitals and clinics need deep excavations for elevator pits, medical gas and mechanical rooms, and tight tolerances for equipment slabs. Hendrick Health announced an $80 million expansion called Project 2010 with a four-story patient tower, new surgery facilities, Hendrick Children's Hospital and a physician office building, the kind of program that depends on careful excavation, shoring and coordination around live operations. See our pages on hospital construction and medical office buildings.

Schools, churches and civic buildings generally need shallower footings but larger footprints, with storm and sanitary connections that start from the excavation. School projects also bring schedule pressure tied to the academic calendar, so we plan excavation to finish well before slab work needs to begin.

Who does what on the excavation

Utilities and earthwork stay with specialist firms, and we coordinate those trade partners, selecting excavation crews for the soil, depth and equipment. A single project manager carries the plans, the inspection schedule and the safety requirements so that the owner is not managing separate subcontractors for the dig, the shoring and the backfill.

The concrete crews who come after the dig are ours, and their input goes back into the excavation plan: how much working room the forms need, where the pump will set up, which side the trucks will approach. That feedback loop is how a footing trench ends up the right width for the forms instead of just wide enough to dig.

What drives excavation cost

The principal drivers are depth, soil type, groundwater, access and disposal. A shallow footing in open ground costs a fraction of a deep pit in a congested yard, and hard caliche or rock can double the production time. Shoring and dewatering are often the largest swing items, and we try to price them with the geotechnical report open rather than assume ideal conditions.

Disposal and import are the next driver. The City of Abilene lists a $30.3 million rehabilitation of the Northeast Water Treatment Plant in the design phase, a scale of civic work in which every cubic yard of spoil has a defined destination and a cost. On private projects we offer the owner choices: reuse on site, stockpile for later, or haul off, with clear unit prices for each.

Sequencing the dig against the pour

We schedule excavation so the open hole stays open for the shortest practical time. That usually means locates and layout first, excavation and shoring next, inspection of the subgrade, then forms, steel and the pour in quick succession. Open excavations are weather exposure, and a heavy storm can cave a wall or flood a footing line in an afternoon.

When a project has multiple pits or footing lines, we divide the work into zones and excavate only as far ahead of the concrete crew as the inspection schedule allows. Hold points with the owner's inspector are booked on day one so that nobody is waiting on a signature while a trench dries out.

What an excavation package includes

A typical package covers layout from the survey control, clearing of the work area, excavation to the shown depths and slopes, shoring or sloping as required, subgrade trimming and inspection, stockpiling or hauling spoil, and backfill with approved material after the structure is complete. We list assumptions about groundwater, rock and unsuitable material so that the owner knows where unit prices apply.

Where the excavation feeds site utilities, we coordinate with trenching and backfill so that pipe bedding, tracer wire and testing follow in order. On industrial campuses, industrial and manufacturing owners often add equipment pits and containment basins to the package, and each is priced on its own line to keep the scope easy to compare.

Plan the excavation before the dig

Bring the foundation plan, boring logs and your pour date. We can walk the site, mark the locate questions and send back a written excavation sequence with hold points for your inspector.

Common Questions

At what depth does an excavation need shoring?

Trench and excavation rules require protection at a depth set by the safety regulations and the soil class, and the competent person on the job makes the call in the field. Dry Abilene clay can look stable until it cracks, so we do not rely on appearance. We price sloping or shoring into the proposal when depth or soil points to it.

What happens if we hit rock or caliche that was not on the borings?

We halt the dig, record the condition with photographs and measured depths, and bring the owner and engineer into the decision. Options include ripping, hammering or revising the depth. The proposal states how unforeseen hard ground is priced, so the discussion is about the field condition and not about the contract language.

Do you handle the locate calls and permits?

We coordinate the locate request and verify marks against the utility drawings. Permits for right of way work or street cuts go through the local permit office, and we line up the paperwork with the general contractor so inspections are booked before digging begins.

Can you dig next to an occupied building?

Yes, with a plan. We evaluate the adjacent footing depths, set exclusion zones, monitor for movement where needed and schedule noisy work around the occupant. For hospitals and schools we agree on hours, routes and dust control before mobilizing.

How is spoil handled when there is no room to stockpile?

We load directly to trucks and haul to an approved destination, or stage the material in a nearby holding area with the owner's permission. That decision affects the price, so we raise it at the start rather than during the dig.