Soil Conditions in Mission Viejo
Orange County presents a range of subsurface conditions. Here's what we encounter most frequently.
Capistrano Formation
Much of Mission Viejo is underlain by the Capistrano Formation, a Miocene to Pliocene-age marine sedimentary unit consisting of massive siltstones and fine-grained sandstones. These soils can be weak and compressible when weathered, and they are associated with landslide activity on slopes throughout south Orange County.
San Onofre Breccia
The San Onofre Breccia is exposed in portions of the hillside terrain around Mission Viejo. This unit consists of angular to subangular rock fragments in a silty to sandy matrix and can be highly variable in strength and permeability. Grading through San Onofre Breccia requires careful observation by the geotechnical engineer to manage material variability.
Monterey Formation (Expansive and Compressible)
The Monterey Formation, consisting of siliceous shale, diatomaceous siltstone, and porcelaneous mudstone, underlies portions of the Mission Viejo area. These soils are known for high expansion potential and compressibility, and foundations on Monterey Formation materials typically require special design to address differential settlement and volume change.
Landslide-Prone Hillsides
Mission Viejo's hilly terrain includes multiple mapped ancient and recent landslide deposits. These areas are subject to slope failure, particularly when exposed to increased moisture from irrigation, poor drainage, or heavy rainfall. Slope stability evaluation is a critical component of geotechnical investigation for any hillside project in the city.
What We Do in Mission Viejo
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
WQMP preparation, LID compliance, 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 Mission Viejo
ADU / Accessory Dwelling Unit
Soils reports and grading plans for ADU construction, including slope stability evaluation for hillside lots throughout Mission Viejo.
Hillside Custom Home
Comprehensive geotechnical investigation with slope stability analysis, retaining wall design, and grading plans for custom homes on Mission Viejo's hillside lots.
Pool and Retaining Wall
Foundation investigation and engineering for swimming pools and retaining walls on sloped sites, addressing surcharge loading and drainage requirements.
Single-Family Remodel and Addition
Geotechnical evaluation for additions and remodels on existing hillside properties, including assessment of existing fill conditions and slope stability impacts.
Working With County of Orange Building Division (OC Public Works)
Mission Viejo contracts with the County of Orange for building and grading plan check services. OC Public Works reviews grading plans, geotechnical reports, and stormwater compliance documents. Geotechnical reports are reviewed by the County's geotechnical staff or contract reviewer. Projects must also comply with Mission Viejo's municipal code and specific plan requirements where applicable.
What Makes This Jurisdiction Distinct
Slope stability analysis required for hillside projects due to prevalence of landslide-prone formations
WQMP required per the San Diego Regional Water Quality Control Board South OC MS4 permit, including hydromodification management
Grading permits require designation of a geotechnical engineer of record and engineering geologist for hillside sites
Ancient landslide mapping must be addressed in geotechnical reports for properties within or adjacent to mapped landslide areas
Enhanced erosion control measures required for grading during the rainy season (October 1 through April 30)
Permit submittals for Mission Viejo are processed through the County of Orange OC Public Works office. The County accepts electronic submittals through its online portal. Pre-application meetings can be arranged through the County's building plan check section for complex or hillside projects.
Common Questions — Mission Viejo
Building in Mission Viejo?
Tell us about your project and we'll send you a fixed-fee proposal — typically within one business day.