Methodology
Our methodology for standard penetration testing in Colorado Springs follows ASTM D1586, using a 140-pound hammer dropped 30 inches to drive a split-barrel sampler. We record blow counts for each 6-inch interval to obtain N-values, corrected for overburden and energy efficiency (N60). Borings are advanced using hollow-stem augers to depths of 30–50 feet, depending on project requirements. Samples are collected for laboratory classification and strength testing. For advanced profiling, we integrate cone penetration test (cpt) results, providing continuous stratigraphic logs. Our team ensures all testing complies with local geotechnical standards and ASCE 7 seismic provisions.
Reference Technical Parameters
| Parameter | Reference Value |
|---|---|
| Predominant soil type | Sandstone, conglomerate, claystone (Dawson Arkose) |
| Maximum seismic acceleration (PGA) | 0.15g (MCE, short period) |
| Typical groundwater level | 10–20 feet below ground surface |
| Bedrock depth | Variable, typically 20–50 feet |
| Typical N60 range | 10–50 blows per foot (sandstone); 5–20 (claystone) |
Local Considerations — Colorado Springs
Colorado Springs' geology is dominated by the Dawson Arkose, a sedimentary formation with variable cementation and interbedded claystone lenses. Shallow groundwater can impact excavation stability and require dewatering. The region's moderate seismicity (PGA 0.15g) necessitates site-specific response spectra per ASCE 7. In western neighborhoods (e.g., Old Colorado City), colluvial soils over bedrock pose landslide risks; in eastern areas (e.g., Falcon), alluvial sands and gravels require compaction control. Typical projects include residential subdivisions, commercial buildings, and retaining walls. Our team coordinates with local authorities to address these challenges. For regional operations, we refer to our standard penetration test en Denver hub for broader Front Range expertise.
Request a Quote
Our team reviews your project and issues an initial report at no cost.
Or write us directly at [email protected]
Services in Colorado Springs
Applicable Standards
- ASTM D1586
- ASCE 7-16
- IBC 2021
- Colorado Springs Building Codes
- OSHA 29 CFR 1926
Frequently Asked Questions
What soil types are common in Colorado Springs?
The predominant soil is the Dawson Arkose, a sedimentary rock with interbedded sandstone, conglomerate, and claystone. Surficial soils include alluvial sands and gravels along creeks, and colluvial deposits on slopes. Claystone layers can be expansive and require special foundation design.
Is seismic design required in Colorado Springs?
Yes, per ASCE 7, Colorado Springs is in Seismic Design Category B (moderate risk). Site-specific ground motion analysis may be needed for critical facilities. The mapped PGA is 0.15g, but local soil amplification can increase demands, making standard penetration testing essential for site classification.
Are geotechnical investigations mandatory for new construction?
For most commercial and multi-family projects, the Colorado Springs Building Code requires a geotechnical report. Single-family homes may be exempt, but lenders often require soil testing. Standard penetration testing provides the N-values needed for foundation design and compliance.