Whether you're breaking ground for a new project or tackling foundation work, MMS machines are built to get the job done. This guide walks you through the full excavation process, offering practical advice on equipment selection, jobsite safety standards, and how to recognize the difference between professional-quality work and poor workmanship.
What Is Construction Site Excavation?
Excavation is the controlled removal of soil, rock, and debris to prepare a construction site for building work. But excavation is far more than simply “digging dirt.” It requires careful planning based on soil conditions, site layout, and the location of underground utilities.
Step 1: Site Assessment & Planning
Before any machine touches the ground, you need a clear picture of what you're working with.
Soil testing is the first priority. Soil composition directly affects how you dig, what equipment you use, and how deep you can safely go without shoring. Clay soils behave very differently from sandy loam or rocky ground.
Utility locating is non-negotiable. In the US, you're required by law to call 811 before digging. This triggers a utility marking service that flags underground gas, electric, water, sewer, and telecom lines. Even with markings, treat the area within 18–24 inches of any flag as a hand-dig zone.
Topographic survey establishes the existing grade so your team can calculate cut/fill volumes. This prevents surprises mid-job when you realize you need to haul out three times more dirt than budgeted.
Permits vary by municipality. Most jurisdictions require an excavation or grading permit for anything beyond minor landscaping. Building departments typically want to see a site plan showing drainage, setbacks, and utility conflicts before issuing approval.
Step 2: Site Clearing
Once planning is complete, the site gets cleared before any excavation depth work begins.
This means removing vegetation, trees, stumps, existing concrete or asphalt, and any surface debris. On tighter residential or commercial sites, this is often where a mini excavator earns its keep. A full-size machine simply can't maneuver through a backyard gate or work close to a structure without causing collateral damage.
Topsoil-typically the top 6–12 inches.
If demolition is part of the scope, this is when it happens. Concrete pads, old foundations, and underground tanks need to come out before excavation proceeds.
Step 3: Excavating & Grading
This is the core work. The approach varies based on the type of excavation:
Cut excavation removes material to lower grade.
Trench excavation creates narrow, deep cuts for utility lines, footings, or drainage pipes. Trenches deeper than 5 feet require protective systems (shoring, sloping, or trench boxes) per OSHA 29 CFR 1926 Subpart P.
Basement/mass excavation involves removing large volumes of material to a specified depth. These projects typically require larger equipment and a clear plan for soil disposal.
Grading follows excavation-shaping the subgrade to the correct elevation and slope.
Equipment Matching
Choosing the right machine for your specific jobsite and workload is extremely important. For tight or confined spaces, a compact machine is usually the best choice. On larger projects, you’ll need equipment that matches the scale and demands of the job. Just as important, don’t overlook attachments,pairing your excavator with the right attachment setup can make a major difference in efficiency and performance.
The MMS MS20 Pro 2-ton mini excavator, for example, reaches a digging depth of 81.1 inches with a Kubota D902 engine that keeps fuel consumption low on longer jobs. Its 360° rotation means you can work along a fence line or inside a tight cut without repositioning the tracks.
For even more confined access, or projects where you need to pass through a standard gate-a 1-ton machine like the MS10H with an enclosed cab keeps the operator protected while maintaining a compact footprint.
Step 4: Foundation Preparation
Subgrade compaction is often overlooked but directly impacts whether your foundation moves over time. The native material is typically compacted to 95% of its maximum dry density (verified by a Proctor test).
Drainage provisions get installed at this stage. Perimeter drain tile around footings, sump pit excavations, and any underdrain systems need to be roughed in before concrete is poured. Fixing drainage problems after the fact is expensive and often requires tearing out finished work.
Elevation verification -a surveyor or grade rod check confirms the bottom of the excavation matches the design elevation. Being off by even 2–3 inches on a footing depth affects how concrete volume, rebar placement, and anchor bolt heights all line up.
Step 5: Utility Trenching & Drainage
Parallel to or immediately following foundation work, underground utilities get installed. This includes water service lines, sewer laterals, storm drain connections, electrical conduit, and gas lines.
Trench widths are specified by the utility being installed,typically 6–12 inches wider than the pipe diameter on each side to allow for bedding material and compaction.
Backfill sequence for utility trenches matters: bedding first, then select fill in 8–12 inch lifts with compaction at each layer. Improperly backfilled trenches settle, which causes pavement cracking, pipe joint separation, and surface depressions.
For this type of precision trenching work, the MMS 1.5-ton MS15 Pro with its 67-inch digging depth and tight turning radius handles standard utility trench depths without overexcavating.
Step 6: Backfill, Compaction & Site Restoration
After underground work is complete and inspections are passed, the site gets backfilled.
Not all fill material is equal. Structural backfill typically requires granular material with specific gradation limits.
Each lift gets compacted before the next goes in. Skipping this step is the most common cause of settling sidewalks, cracked aprons, and uneven finished grades down the road.
Final grading establishes the finished topography-parking grades, lawn areas, swales, and approach slopes.
The MMS MS12 mini excavator with a hydraulic thumb is particularly useful here.
Excavation Safety Requirements
Excavation work is considered one of the more hazardous activities in construction. According to OSHA, any excavation that reaches a depth of five feet or more presents a significant risk of cave-ins.
Key safety requirements:
- Competent person on site-OSHA requires a designated competent person to classify soil, inspect the excavation daily, and authorize protective systems.
- Protective systems-Sloping (cutting back the trench walls), shoring (hydraulic or timber), and trench boxes are the three main approaches. Selection depends on depth, soil type, and adjacent loads.
- Spoil pile setback-Excavated material must be kept at least 2 feet from the edge of the excavation to prevent surcharge loading on the trench walls.
- Egress-Any trench 4 feet or deeper requires a ladder, ramp, or other means of egress within 25 feet of workers.
- Water control-Standing water in a trench weakens the walls. Dewatering pumps need to be staged before work begins if groundwater is encountered.
- Atmospheric testing-In any trench more than 4 feet deep where hazardous atmospheres are possible (near landfills, gas lines, or organic soils), air testing is required before entry.
Types of Excavation in Construction
You first need to clearly understand the type of project you are working on before you can properly plan the next steps of your excavation work:
Topsoil excavation-Removing the upper layer of soil (6–12 inches). The most common first step on any site.
Rock excavation-Requires specialized equipment (hydraulic breakers, rippers) or blasting. Significantly more expensive and time-consuming than soil work. A hydraulic breaker attachment on a compact excavator handles smaller rock volumes without the cost of a full blasting mobilization.
Muck excavation-Wet, unstable soil that must be removed and replaced. Common near water features and low-lying areas.
Earth excavation-Standard removal of soil below the topsoil layer. The bulk of most construction site excavation falls here.
Trench excavation-Narrow, deep cuts for utilities and footings. Linear footage and depth determine equipment and shoring requirements.
Basement excavation-Large-volume, deep cuts. Typically the most complex type on a residential project due to depth, adjacent structures, and dewatering requirements.
Choosing the Right Excavator for Construction Site Work
The two questions that actually matter: can the machine reach depth, and can it fit on the site?
Full-size excavators (20+ tons) are efficient on large sites with open access and high material volumes. They're not practical in tight residential settings.
Mini excavators (1–2 tons) cover the majority of residential and light commercial excavation needs. They fit through standard gates (as narrow as 39 inches with tracks retracted), cause minimal ground disturbance, and can be transported on a standard utility trailer.
MMS produces factory-direct mini excavators ranging from 0.8 to 2 tons with Kubota and Briggs & Stratton engines. The lineup includes:
- MS20 Pro (2-ton) -Kubota D902 diesel, 81.1-inch dig depth, hydraulic thumb, side swing. Best for foundation work and heavier residential excavation.
- MS15 Pro (1.5-ton) -B&S gasoline engine, 67-inch dig depth. Versatile for utility trenching and landscaping.
- MS12 (1.2-ton) -RATO 13.5HP, hydraulic thumb. Compact, good for confined sites and general-purpose digging.
- MS10H (1-ton with cab) -Enclosed cab, electric wipers, ideal for longer-duration work in variable weather.
All models are compatible with standard mini excavator attachments -hydraulic breakers, augers, grapples, rippers, and buckets.
Common Mistakes to Avoid
Skipping the utility locate. Even marked lines have tolerance. Treat every marked area as potentially inaccurate and slow down near flags.
Overexcavating and then filling back. Disturbed soil has lower bearing capacity than undisturbed native material. If you dig past your design depth, the solution isn't to just throw dirt back in,you need engineered fill and compaction verification.
Ignoring water. Groundwater encountered mid-excavation changes the whole job. Have a dewatering plan before you hit it, not after.
Wrong machine for the space. Running a full-size excavator in a backyard to save time often ends up costing more in landscape repair and access damage than the time saved.
Inadequate spoil management. Where does the dirt go? This question needs an answer before the job starts.
Final Thoughts
Successful excavation on a construction site depends on organized planning, using the right machine, and choosing the proper attachments for the job. You can follow the steps in this guide to help keep your excavation work efficient and under control. If you’re looking for an excavator, check out MMS mini excavators — all backed by a one-year warranty.
