Spoil from a drilled pier in an old industrial corridor is a waste stream before it is a pile of dirt. Neighborhood activism in Globeville and Elyria-Swansea won a 1994 settlement with ASARCO that funded soil cleanup, a sign of legacy smelter contamination that belongs in due diligence near those industrial areas. A pier rig brings that soil to the surface, so the environmental question has to be answered before the first hole is drilled.
Drilled piers are the workhorse deep foundation for Front Range industrial buildings. A rotating auger bores a shaft to the depth the geotechnical report calls for, a reinforcing cage is lowered in, and concrete is placed to fill the shaft. The result is a column of concrete bearing on stable material below the zone where moisture changes swell and shrink the soil. It is not complicated in concept, but the quality of a pier is determined by hole stability, cleanout, cage placement and how quickly concrete follows the drilling.
We install piers for tilt-wall warehouses, clear-span manufacturing plants, crane buildings and equipment structures. The decision on whether to use piers rather than another system is covered under deep foundations and piers; this page is about how the piers are built and what we check along the way.
How a pier gets built right
We sequence each shaft so the open hole is exposed for as short a time as possible. Drilling, inspection, cage placement and concrete placement happen on the same day wherever the hole allows it. Where groundwater or caving soils appear, we use temporary casing or slurry methods to hold the shaft open, and the concrete is placed by tremie so it displaces water from the bottom rather than falling through it and segregating.
On Front Range clay and claystone, the usual design is a straight shaft socketed into firm bedrock, with enough dead load to resist the uplift that swelling soil can exert on the shaft. The engineer sets the diameter, the length and the reinforcement. We verify the bottom of each hole, remove loose cuttings and confirm the socket reached the required material, with the geotechnical inspector witnessing the key steps. The frost depth in the design criteria for Lakewood is 36 inches, and the shaft-top details are designed to match.
Layout, drilling, reinforcement and concrete
Scope begins with survey control. Pier locations are staked from the building grid, and each stake is verified before the rig moves in. We prepare a working surface so the rig stays level and does not rut, then drill, inspect, place the cage and pour. Cages are tied or welded off-site and lifted with a crane, with spacers that hold the required cover. Anchor bolts, dowels and cast-in plates for the next phase are set into the top of the pier to the survey tolerance.
After curing, the pier tops are exposed and trimmed, grade beams and pile caps are formed, and void forms are installed beneath them. For lightly loaded buildings, a pier-and-grade-beam system carries the walls. For steel or crane buildings, a pier and pedestal carry each column. The steel erection sequence that follows is described under structural steel erection, and the crane building requirements are handled in high-bay crane-ready buildings.
Open shafts, spoils and environmental screening
Open shafts are a fall hazard and a trapping hazard. We cover them at the end of every shift and whenever work stops for a significant period, and we establish an exclusion zone around the rig so no one stands near the auger as it turns. Utilities are located before drilling, with potholing where lines are close to the pier. A drilled shaft that strikes a conduit is a stop-work event, so we spend the time up front.
On sites with industrial history, the spoils may need screening, segregating and disposal that follows environmental rules. We coordinate with your environmental consultant, set aside a stockpile area, and keep the drainage from the spoil away from stormwater inlets. In the north Denver industrial area, where both I-25 and I-70 cross the neighborhood, that screening is routine rather than exceptional.
What drives cost on a pier package
Quantity, depth and ground conditions control the price. Short, dry shafts in uniform clay are inexpensive per foot, while holes that need casing, slurry or rock coring cost more. Mobilization is a significant fixed cost, so the number of piers and the layout of the site matter. We price on a unit basis with allowances for conditions beyond the borings, and we list the assumptions so an unexpected condition has a defined cost.
Climate adds its own cost. Eagle County amends IBC 1809.5 to require footings subject to frost to be at least 48 inches deep, and mountain sites bring cold-weather concrete protection, restricted access and shorter working seasons. For projects in the high country such as Vail and Eagle County, we plan the work around frost, snow and rig access, and we price winter protection explicitly.
Buildings that depend on piers
Large clear-span buildings are the main user, because column loads are high and the slab must remain flat. Hangars are a good example, with wide spans, big doors and unusual loads at the door tracks. Our aircraft hangar work uses the same discipline. The foundation must hold the door-track alignment, and drilled piers help because they resist the seasonal movement that can bind a large door.
Production plants are the other regular user. Equipment structures, pipe racks and mezzanines place concentrated loads on the soil, and piers deliver them to a stable layer. Manufacturers expanding a plant often need piers for the new addition that match the old settlement behavior. Our work for advanced manufacturing owners includes matching new foundations to the performance of the existing structure and checking the tie-in details.
Drill after the soil question is answered
Send the geotechnical report, the foundation plan and any environmental findings, and we will return a drilling plan, unit prices and an inspection protocol. Contact Industrial Contractors of Colorado to begin.
Common Questions
How many piers does a typical warehouse need?
It depends on the column grid, the roof load and the tilt panels. A warehouse with panels bearing on grade beams has a pier line along the walls and interior piers at columns. The structural drawings give the count, and we price from them. The geotechnical report gives the depth.
What if the hole fills with water?
We stabilize it with casing or slurry and place concrete by tremie from the bottom. The method is selected before drilling, because the wrong method can ruin a pier. We note groundwater levels in the inspection records for the engineer.
Who inspects the piers?
A special inspector retained by the owner or engineer observes drilling, checks depth and the bottom of the hole, verifies the cage and witnesses the pour. We provide access and keep a log. The inspector's report becomes part of the foundation acceptance.
How close can piers be to an existing building?
It depends on the soil, the existing footing and the rig. We can drill with lower vibration than driven piles, but excavation can still affect neighboring foundations. We work with the engineer on offsets, monitoring and sequence.
How long does it take to drill and pour a pier?
A typical shaft takes a few hours when conditions are good. Productivity depends on depth, soil and casing. We plan a daily count that keeps the holes within the day's pour, so none is left open overnight.