Photo: Chuckmor (CC BY-SA 3.0) via Wikimedia Commons
Winnebago County, IA Contractor directory
Excavation contractors in Winnebago County, IA
3 verified excavating and site work contractors serving Winnebago County.
County excavation guide
Ground conditions and project requirements in Winnebago County
Use this local research to understand soil, seasonal constraints, permits, and jobsite logistics before choosing a contractor.
Skip to 3 contractorsSoil Regime ProfileEPA Ecoregion 47, 46 (Western Corn Belt Plains, Central Irregular Plains)
Iowa Des Moines Lobe Till & Prairie Pothole Plain
Dominant Soil Order: Mollisols / Alfisols
Parent Material: Wisconsinan Des Moines Lobe Glacial Till (Clay Loam and Loam) over Loess-Capped Pre-Illinoian Till
Iowa's young glacial lobe is prairie-flat and clay-loam country: nearly level ground, deep Des Moines Lobe till, loess caps on the upland edges, and the highest water tables in the region. Digging is easy in the soils but the practical work is water: hydric soils occupy a quarter of the average county, prairie-pothole wetlands and seasonal potholes dot the northern counties, and median water tables sit 13 inches down. Trench stability in wet clay loam is the everyday safety issue, and septic systems commonly need fill, mound, or at-grade designs because seasonal perched water and tight clay subsoil shorten separation distances. Shrink-swell is modest (3 percent average) but not negligible in the clay-loam subsoils. Frost depth runs 42 inches. Rock is essentially absent from the lobe (bedrock within 50 inches on about 1 percent of land), so bids are shaped by dewatering, wet-weather access, and compaction control, not rock.
Geographic Footprint:Iowa's Des Moines Lobe counties (the north-central and northwestern third, Des Moines through the Minnesota border) are young glacial till: flat prairie, clay loam, high water tables, and prairie-pothole wetlands. Septic and foundation work turns on water management, not rock.
Geotechnical Baseline
Physical Ground Conditions & Soil Properties
Shallow Bedrock (<50 in)
0.0%of county land area
Deep soil mantle; rock refusal rare for standard basement or trench cuts.
High Shrink-Swell Clay
2.3%expansive soil
Low volumetric expansion risk in native subgrade.
Median Water Table Depth
4inches from surface
Shallow water table; active dewatering or sumps needed for deep trenching.
Hydric / Wetland Soils
50.6%hydric coverage
Indicates poor natural drainage and potential jurisdictional wetland pockets.
Steep Terrain (Slope >15%)
0.9%of terrain
Predominantly gentle to rolling slopes suitable for wheeled earthmoving.
Septic Severe Limitations
88.0%severe rate
High rate of conventional drainfield limitations; engineered or drip systems often required.
Dominant Soil Textures:Clay loamLoamSilty clay loam
Surface Stones / Boulders: 48.1% coverage
Compliance & Permitting
Earthwork Regulations & Permit Thresholds
Stormwater & Erosion Control
Iowa DNR NPDES General Permit No. 2 (Storm Water Discharge Associated with Industrial Activity for Construction Activities), effective Mar 1 2023 to Feb 29 2028; covers construction disturbing one acre or more, and smaller sites that are part of a larger common plan that will ultimately disturb one acre or more. Outstanding Iowa Waters watersheds require an individual permit.
Administers NPDES stormwater discharge coverage for land-disturbing construction activities.
State Threshold:1.00 Acre
Local Threshold:Follows state
Onsite Wastewater & Utilities
Winnebago County Environmental Health
Jurisdiction over septic tank permits, soil evaluation perk tests, and drainfield sizing.
Housing on Septic:55.0%
Soil Evaluation:Percolation test or soil analysis (soil boring about 6 ft) by a licensed engineer or approved septic contractor; 3 ft separation to limiting layer
811 One-Call Requirements
Iowa One Call (811)
Mandatory notice window: 48 hours prior to mechanized earthwork (excluding weekends and legal holidays).
Licensing & Clearing Permits
Weather & Ecology
Seasonal Constraints & Clearing Windows
Frozen Ground Days
90days / year
Typical days with sub-freezing soil conditions affecting digging.
Wet Season Months
April, May, June, July, August
Peak precipitation window requiring sediment traps and soil aeration.
Supply Chain & Hazards
Logistics, Aggregate Sources & Geohazards
Aggregate & Material Supply
Fertile Quarry
Nearest active quarry: 13.8 miles haul distance.(19 active crushed stone/sand operations within 50 miles).
Flood & Hazard Overlay
FEMA 100-Yr Flood:7.3%(100% NFHL digital map coverage)
NWI Wetlands:7.2%jurisdictional coverage
Karst Terrain & Sinkhole Risk: Low
98.9% of county underlain by soluble carbonate rock formations.
HUC8 Primary Watersheds:Winnebago, Shell Rock, East Fork Des Moines, Blue Earth, Upper Iowa
Public conservation land: 13.1% (USGS PAD-US).
Area-specific FAQ
Do I need to call before digging in Winnebago County?
Yes. You should contact Iowa One Call at least 2 working days before any digging so underground lines can be marked.
How deep do footings need to be in Iowa?
In Iowa, footings typically need to extend below the frost line, which is around 48 inches here. A local contractor will confirm the code requirement for your site.
Verified local listings
Excavation contractors serving Winnebago County
3 verified listings
No reviews yet
No reviews yet