Soil Conditions in Pomona
Los Angeles County's geology is as varied as its neighborhoods. Here's what we typically find.
Alluvial Fan Deposits
Central and southern Pomona sit on alluvial fan deposits from San Antonio Creek and tributaries — generally good bearing but variable density. Site-specific verification is needed for foundation design.
San Jose Hills Bedrock
Northern Pomona rises into the San Jose Hills with sedimentary bedrock — sandstone, siltstone, and conglomerate of the Puente Formation. Hillside lots require slope stability evaluation.
Expansive Soils
Weathered bedrock and residual soils in the hills and transitional areas exhibit moderate to high expansion — affecting foundation and slab design.
Liquefaction Susceptibility
Lower-lying portions of the city with shallow groundwater may be susceptible to liquefaction. Seismic Hazard Zone mapping triggers mandatory investigation where mapped.
What We Do in Pomona
Soils Reports
Geotechnical investigation for residential, commercial, and hillside projects — prepared to City of Pomona standards.
Learn more →Grading & Drainage Plans
Grading design for valley and hillside lots compliant with City requirements.
Learn more →Compaction Testing & Inspections
Nuclear gauge testing and field inspections during grading and foundation construction.
Learn more →Stormwater / LID / WQMP
LID compliance and stormwater management for LA County MS4 Permit requirements.
Learn more →Hydrology & Hydraulic Reports
Pre- and post-development drainage analysis for City and LA County Flood Control compliance.
Learn more →Erosion Control (SWPPP / ESCP)
Construction-phase stormwater pollution prevention for grading permits.
Learn more →Street Improvement Plans
Sidewalk, curb, gutter, and driveway approach design for public ROW.
Learn more →Utility Plans
Water, sewer, and storm drain design coordinated with City utilities.
Learn more →Project Coordination
One point of contact managing structural, MEP, surveying, and specialty consultants.
Learn more →We also coordinate with your structural engineer, architect, MEP consultants, and other project team members to ensure our deliverables integrate with the overall design — one point of contact for your geotechnical and civil engineering scope.
What People Build in Pomona
ADUs & Residential Additions
Pomona's affordable housing stock and large lots drive ADU activity. Soil conditions vary between the valley floor and the hills.
Multi-Family Housing
Apartment and townhome development on infill sites — geotech and civil engineering.
Commercial & Industrial
Warehouse, logistics, and commercial projects along the I-10 corridor and Holt Avenue — geotech through construction support.
Hillside Development
Custom homes and improvements in the San Jose Hills — slope stability and engineered grading.
Revitalization & Adaptive Reuse
Downtown Pomona and Arts Colony area redevelopment — geotech for renovation and infill projects.
Pool & Retaining Wall Engineering
Foundation design for pools and retaining walls in expansive soil zones.
Working With City of Pomona — Development Services Department
The City of Pomona Development Services Department handles building permits and plan check. Pomona is actively encouraging development with streamlined review for qualifying projects.
What Makes This Jurisdiction Distinct
Soils reports required for new construction, hillside lots, and projects in mapped hazard zones
LA County MS4 Permit governs stormwater — City enforces local LID requirements
Seismic Hazard Zone mapping for liquefaction and landslide applies to portions of the city
Fault investigation reports coordinated through our partner engineering geologists when required
Active revitalization programs — streamlined permitting for qualifying projects
Downtown Pomona Specific Plan area has development standards
Submittals through City of Pomona Development Services, 505 South Garey Avenue, Pomona 91766.
Common Questions — Pomona
Building in Pomona?
Tell us about your project and we'll send you a fixed-fee proposal — typically within one business day.