Soil Conditions in Poway
San Diego's geology varies dramatically from neighborhood to neighborhood. Here's what we see most often.
Poway Conglomerate
Poway is famous for its namesake formation — the Poway Conglomerate, a distinctive cobble-bearing sedimentary rock with clasts sourced from far-away volcanic and metamorphic terrains. This formation is extremely well-cemented and difficult to excavate but provides excellent bearing support.
Granitic Saprolite and Decomposed Granite
Eastern Poway and the hillsides are underlain by granitic bedrock in various stages of weathering. Decomposed granite drains well and generally provides good support but can be collapsible when loosely deposited in natural swales.
Valley Fill Alluvium
Poway's valley floor along Poway Creek contains alluvial deposits of variable composition. Some areas have expansive clay in the upper soils that requires mitigation for slab and foundation construction.
What We Do in Poway
Soils Reports
Geotechnical investigation and foundation recommendations for building permits.
Learn more →Grading Plans
Precise and rough grading design with drainage and earthwork calculations.
Learn more →Compaction Testing
Field density testing and fill certification for construction.
Learn more →Stormwater / LID / WQMP
LID compliance, WQMP preparation, and BMP design.
Learn more →Hydrology Reports
Drainage analysis and flood risk assessment.
Learn more →Subsurface Exploration
Drilling, CPT, and test pit programs.
Learn more →Erosion Control Plans
SWPPP and erosion control for grading permits.
Learn more →Street Improvements
Frontage, curb, gutter, and sidewalk design.
Learn more →Utility Plans
Water, sewer, and storm drain design and coordination.
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 Poway
Custom Home
Custom homes on Poway's larger rural-residential lots, often encountering Poway Conglomerate or granitic bedrock.
ADU / Guest House
ADUs on Poway's spacious lots — soils reports required for new detached structures.
Horse Property Improvements
Barns, arenas, and equestrian structures on Poway's rural-zoned properties.
Pool Addition
Pool excavation in Poway can be challenging due to conglomerate and bedrock — soils investigation helps plan the work.
Working With City of Poway Development Services Department
Poway requires geotechnical investigations for new construction and grading permits. The Development Services Department reviews reports as part of the building permit process.
What Makes This Jurisdiction Distinct
Poway Conglomerate and granitic bedrock — reports should include excavation difficulty assessment
Hillside development regulations for properties on slopes over 25%
Large lot residential character — the 'City in the Country' development guidelines affect density and grading
Grading permits required for earthwork over 50 cubic yards
Submit to Development Services at Poway City Hall, 13325 Civic Center Drive.
Common Questions — Poway
Building in Poway?
Tell us about your project and we'll send you a fixed-fee proposal — typically within one business day.