Pasadena's development from a citrus-growing valley into a dense urban hub has reshaped its natural drainage patterns considerably. The San Gabriel Mountains to the north send seasonal runoff through arroyos and alluvial fans that underlie much of the city, creating a landscape where soil loss accelerates when native vegetation is stripped for construction. Our team approaches each site with an understanding of these historical gradients, combining field reconnaissance with laboratory testing to quantify detachment and transport risks before grading permits are issued. For projects near the Eaton Canyon wash or along the foothills, we often pair our erosion analysis with a geotechnical drainage study to evaluate how subsurface water flow interacts with surface runoff, ensuring both slope and flat areas remain stable through wet winters.
We quantify detachment rates using site-specific infiltration and shear data, not regional averages, to design erosion controls that actually perform under Pasadena's intense winter storms.
Service characteristics in Pasadena California
Critical ground factors in Pasadena California
A mobile field trailer equipped with a rainfall simulator and a set of flumes is what we deploy across Pasadena sites to measure actual runoff and sediment yield under controlled intensities. We set up 1m² plots on representative soil units, apply simulated rain at 50 mm/hr for 30 minutes, and collect the eroded material to determine detachment rates and sediment concentration. This on-the-ground approach captures the real variability of the local alluvial fans and colluvial slopes, data that no desktop model can replicate. By correlating these field measurements with laboratory index properties, we build erosion curves specific to each project's soil profile, eliminating guesswork from the SWPPP design.
Our services
Our lab offers three core services tailored to Pasadena's hillside and flatland projects:
Erosion Hazard Assessment
Field-based rainfall simulation and soil sampling to classify erodibility class for every soil horizon on site.
Sediment Basin Design Support
Hydrologic modeling and soil loss calculations to size temporary sediment basins per CASQA guidelines.
Post-Construction Monitoring
Periodic erosion pin surveys and runoff sampling to verify that permanent BMPs are controlling sediment yield as designed.
Common questions
How long does a soil erosion analysis take in Pasadena?
A standard assessment, including field work, lab testing, and a report, typically takes 10 to 14 business days. If your project is on a fast track, we can expedite the field portion and deliver preliminary results within 5 days.
What is the difference between an erosion analysis and a sediment basin design?
An erosion analysis identifies which soil layers are most vulnerable to detachment and quantifies the expected soil loss under design storms. A sediment basin design uses those numbers to size temporary ponds or traps that capture eroded material before it leaves the site. The analysis must come first to provide the input parameters for the basin sizing.
Do I need an erosion analysis for a small residential lot in Pasadena?
If your lot is on a slope steeper than 3:1 or has more than 1,000 square feet of disturbed area, the City of Pasadena typically requires an erosion and sediment control plan. Our analysis gives the engineering basis for that plan, whether your site is a single-family home or a multi-story development.
How much does a soil erosion analysis cost in Pasadena?
The cost ranges between US$790 and US$2,670 depending on the site size, number of soil horizons tested, and whether rainfall simulation is needed. We provide a fixed quote after an initial site walk to scope the work accurately.