Over-Excavation and Recompaction in Midland

When a geotechnical engineer writes that a layer of the existing ground is unsuitable, the answer is usually to remove it and put back something better. Over-excavation and recompaction means digging below the planned subgrade, hauling away soft, organic, loose or expansive soil, and rebuilding the area in controlled lifts to a density the engineer can test. It adds work before the foundation, and it frequently determines whether a slab stays flat for decades or cracks within a season.

We plan the removal as a measured operation instead of a guess. The limits are set by the engineer, staked by the surveyor and checked by the testing firm, and our job is to coordinate the earthwork partners so that the dig, the haul, the replacement material and the compaction occur in a sequence the owner's rep can follow. Midland soils are often firm near the surface, but pockets of fill, old pit backfill and moisture-sensitive layers appear where nobody expects them, and a clear process for handling them keeps the pour calendar intact.

An over-excavation can reach several feet below grade across a wide area, and the edges of that cut must be treated as excavation walls. Sloping, benching or shoring, daily competent-person inspection and clear ramps for equipment are part of every plan we approve. Workers on foot stay out of the swing radius of machines and out of the compaction lane.

Dust and heat are the other concerns. Dry removal in summer sends fine particles into the wind, so water trucks run alongside the dig, and crews are given shade and water breaks. We also ask the testing technician to stay clear of equipment when taking density readings, since a nuclear gauge operator and a roller share the same surface for part of the day.

Depth and area are the first drivers, and the engineer's limits can change after the first cut. Haul distance to an acceptable disposal site is the second. The replacement material comes next, whether it is imported select fill, processed base or on-site soil that has been treated, and its source and haul often cost more than the digging.

Compaction testing, standby time when it rains and re-testing after failed results also appear. We present unit prices for removal, replacement and testing so changes in quantity are easy to price. Where the solution might be treatment instead of replacement, we compare the two with the engineer, and the comparison draws on the methods in lime and cement soil treatment.

The rebuild happens before footings, forms, utilities under the slab and reinforcing, so any delay moves everything behind it. We ask the engineer to review the limits at the first cut, not at the end, and we schedule the testing firm to be on site for each lift. Lifts are placed and tested in a continuous cycle so the rebuilt area is closed up quickly.

Weather can interrupt. A heavy rain on an open over-excavation turns the base to mud, and we put berms, sumps and covers in place before the dig begins. The batch plant is not given a placement date until the rebuild has passed, and the concrete contractor is told the day the pad was accepted instead of the day we hope it will be.

Removal and recompaction sit next to other soil solutions. If the engineer prefers to improve the existing ground, our engineered fill and soil stabilization approach describes that alternative. Once the pad is rebuilt it is trimmed to grade under building pad preparation, and the surface is handed to the foundation and slab crews.

Industrial and warehouse buildings have the largest pads and the largest removals. Developers of those buildings, especially logistics and warehouse developers, tend to ask for a written estimate of removal quantities in the bid so that a surprise in the field does not catch the budget unprepared.

We mobilize trade partners and supervision to Midland and nearby communities. Around the airport, the Spaceport Business Park offers ground-leased sites on 50 acres in its first phase on the southeast side of the field, marketed through the Midland Development Corporation for aerospace and aviation development. Building on land like that means soils and drainage that differ from downtown lots. Our airport area page describes how we approach it.

Roads tie the region together. The Nadine and Tom Craddick Highway, the SH 349 reliever route around the west side of Midland, opened on December 10, 2009, and the former downtown route became Business SH 349-C. In September 2025 the city listed the I-20 and Midkiff signal among projects completed that year. Between Midland and Odessa, those routes define the haul paths we use.

Not every soft spot calls for a big removal. The engineer decides based on test borings, moisture, plasticity and what the building will place on the ground. Shallow organic material, uncontrolled fill, expansive clay and loose sand are the common candidates. We encourage the engineer to walk the cut and mark the limits with paint or stakes.

Documentation matters. We photograph the bottom of each over-excavation, record depth and area, and save the density test numbers for each lift. When a claim arises later about a slab crack or a settlement, a clear record of what was removed and rebuilt protects both the owner and the contractor. We also share the record with the concrete contractor before forms go in, because the thickness of the rebuilt section and the date of the last passing test tell them what they are placing on.

The rebuild is also the moment to settle drainage. A pad that has been dug out and refilled can become a bathtub if the base below it is less permeable than the fill above. We ask the engineer to review the low points and outlets before replacement begins, so water has somewhere to go besides the underside of the slab, and so the grading around the building directs runoff away instead of into the repaired zone.

We need the foundation drawings, intended placement date and geotechnical report to plan the work. We will return a removal and rebuild sequence with testing points, haul estimates and the day the pad can be released to the concrete trades.

How deep does an over-excavation usually go?

Depth comes from the engineer, based on the borings and the load the foundation will carry. It may be as little as one foot or as much as several feet. We start with the plan, check the cut at each stage and adjust only on written direction.

Can the soil we remove be reused?

Sometimes. If testing shows the material meets the fill specification after drying, mixing or screening, it can go back. Organic or highly plastic soil is usually hauled away and replaced with select material.

How do you prove the rebuilt area is good?

The testing firm takes density measurements on each lift and the engineer reviews them. A proof roll with a loaded truck or heavy roller across the final surface finds soft spots that spot tests may miss.

What happens if it rains while the dig is open?

We protect the edges, pump water from the low areas and wait until the base dries enough to work. The engineer may require additional removal if the wet soil has softened beyond repair.