Excavation
Excavation & Site Prep in Union, Oregon: 2026 Guide
Cojo
May 29, 2026
7 min read
Union sits in the southern Grande Ronde Valley along Highway 237, ranch and hay country ringed by the Blue and Wallowa Mountains. It's a high-elevation place with a hard winter, where the valley floor meets the foothills and the ground freezes deep every year. The excavation that supports the ranches, farms, and homes here has to deal with varied soils, snowmelt drainage, and deep frost. A building pad, a drainage fix, a utility run, or a cleared site all start by understanding what's in the ground.
Cojo Excavation & Asphalt brings full earthmoving capability to Union and the surrounding Grande Ronde Valley from its Willamette Valley base. The grading, drainage, trenching, and clearing we do is the groundwork every paving and building project depends on.
Excavation in this country usually sorts into a handful of jobs:
Site grading. Setting the slopes and elevations a project needs — for a pad, a shop, a barn, a driveway, or a lot. On the valley floor and the foothill benches around Union, grade controls where water and snowmelt go. Our site grading cost in Oregon guide explains what drives a grading job.
Drainage. Snowmelt off the surrounding mountains and seasonal high water make drainage critical here. We cut swales, set culverts, install footing and French drains, and reshape ground to carry water away from structures.
Utility trenching. Water, power, septic, and other lines need correct depth and backfill. At Union's elevation, frost runs deep, and we set water lines below it so they don't freeze.
Land clearing. Removing brush, stumps, old structures, and debris to open ground for new use on the ranch and hay properties common around Union.
Excavation is one of the hardest trades to price unseen, because much of the cost stays buried until the bucket finds it. The factors:
Our excavation cost in Oregon guide details these. We don't price excavation by phone — the honest number comes from walking the site.
Union County and the State of Oregon set thresholds for when ground disturbance triggers erosion-control and stormwater requirements. Larger projects, work near Catherine Creek and the valley's other waterways, and jobs disturbing more than a set area can require an erosion and sediment control plan. With as much water as moves through this valley, the proximity rules matter. We know where those thresholds fall and build compliance in from the start.
Every Union excavation job starts with an 811 locate. Before we break ground, public utilities — gas, electric, telecom, water — get marked. It's the law and it's smart. Ranch and rural properties around Union often carry private lines too — stock-water runs, old water lines, abandoned septic, power to outbuildings — that public locates won't show. We talk through your property history so the bucket doesn't find something costly.
Good excavation is invisible; bad excavation shows up as a settling pad, a driveway base that heaves in the deep frost, or a soft-scarred trench. We treat the dirt work as the foundation it is, because the paving, building, or driveway on top only lasts if the ground was prepped right — and in Union's winters, base and drainage decide everything. For existing-surface fixes once the earthwork's done, see driveway repair in Union.
A town Union's size can't support a full excavation outfit with equipment idling between jobs. So property owners bring in a regional contractor with the capacity for real earthmoving. Cojo carries the dozers, excavators, and trucks, and serves the whole Grande Ronde Valley — see our Union County excavation coverage and our excavation in La Grande guide for the county hub. We mobilize for Union work with capacity a small local operator can't match.
Excavation pricing depends on your site. Cojo Excavation & Asphalt provides free, no-obligation site assessments for Union-area property owners. We walk the ground, talk through your project, and give you a real number.
Request a free site assessment — we respond within 24 hours.
View our completed excavation projects and learn more about our professional excavation services.
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