Fullerton sits at an elevation of about 164 feet above sea level, and its varied topography includes areas where hillsides were cut and valleys filled during development. That history means many building sites here rest on engineered or undocumented fill. When we analyze foundations on fill in Fullerton, the first step is to determine the fill type, thickness, and compaction level. We use ASTM D1586 for SPT borings and ASTM D2487 for soil classification. These tests quantify the bearing capacity and compressibility of the fill layer. Before designing a slab or footing, the team often recommends a geophysical survey such as tomografia sismica to map the fill-native soil contact across the site.
A foundation on undocumented fill can settle 2 to 4 inches over time; proper analysis prevents structural damage and costly repairs.
Methodology and scope
Local considerations
We bring a portable drill rig with a 3-inch hollow-stem auger to Fullerton sites. The rig reaches depths of 30 to 50 feet to get through the fill and into native soil. During drilling we log each soil layer and take undisturbed samples with a Shelby tube. The biggest risk in fill analysis is missing a zone of poorly compacted material that can sink under load. That's why we space borings no more than 50 feet apart on large lots. The team also runs a plate load test on compacted fill to confirm modulus of subgrade reaction before the slab is poured.
Applicable standards
IBC 2021 (Section 1806 – Bearing capacity of soils), ASTM D1586-18 (Standard Test Method for SPT), ASTM D2487-17 (Standard Practice for Classification of Soils for Engineering Purposes), ASTM D5333-20 (Standard Test Method for Measurement of Collapse Potential of Soils)
Associated technical services
Undocumented Fill Investigation
For sites where fill history is unknown, we drill borings to a depth of 1.5 times the fill thickness. We log soil types, run SPT at 5-foot intervals, and collect samples for lab testing. The report includes bearing capacity, settlement estimates, and recommendations for removal or ground improvement.
Engineered Fill Verification
When fill was placed under a compaction specification, we perform field density tests (ASTM D6938) and laboratory compaction curves to verify compliance. We also conduct plate load tests to measure the subgrade reaction modulus. The final report confirms whether the fill meets the design criteria for foundations.
Typical parameters
Frequently asked questions
How deep do you drill to analyze foundations on fill in Fullerton?
Drilling depth depends on fill thickness. We typically drill to a depth of 1.5 times the estimated fill thickness, with a minimum of 20 feet. If fill is 15 feet deep, we drill to at least 22 feet to confirm native soil conditions beneath.
What is the typical cost for a fill analysis in Fullerton?
The cost ranges between US$740 and US$2,250 depending on the number of borings, lab tests, and site accessibility. A basic investigation with two borings and standard lab tests runs on the lower end; deeper fills or additional collapse testing increase the price.
Can you build on undocumented fill without analysis?
Building on undocumented fill without analysis is risky. The fill may contain organic material, debris, or loose zones that settle unevenly over time. Even a 1-inch differential settlement can crack slabs and walls. IBC 2021 requires a geotechnical investigation for any fill deeper than 3 feet.
How long does the analysis take from sampling to report?
Field sampling takes one to two days for a typical site. Lab tests (compaction, Atterberg, collapse) require another 7 to 10 business days. The final report is delivered within 2 weeks of sampling. Rush orders can be arranged for an additional fee.