Helping our clients make wise investments is part of what we do. Often homeowners and contractors want to know, “Is a soil engineering inspection really necessary?” and “Can I just look at it myself?”. One builder asked us if he could bring us the soil from the bottom of the footing trench so that he could save on the cost for the geotechnical engineering footing inspection. In the long run, it is actually most cost-effective to invest in a geotechnical engineering inspection. This case illustrates why.
The “Great Wall”
A builder of a mini storage wanted to build a keystone retaining wall to enhance the aesthetic appeal of the project along a highway. However, he chose to not invest in an soil engineering inspection.
He hired a soil engineer to perform a limited study with minimum scope to determine bearing capacity and soil friction angle. Then, the information was given to the retaining wall system design engineer. The soil engineer recommended inspection of the footing subgrade and installation of geogrid. Contrary to the recommendation, the builder opted out of the engineering inspection. By skipping the geotechnical engineering inspection, he appeared to save about $1000.
Within a few years, the wall started to fail due to settlement of the foundation on loose soils. The settlement caused the face blocks of the wall to fall apart. As time passed, the whole retaining wall sagged due to insufficient pull-out resistance, which was likely caused by improper installation of the geogrid. Eventually, the entire retaining wall had to be completely removed because of unsafe conditions. The cost of removal was reportedly 1 million dollars.
A geotechnical engineering inspection completed at a fraction of the cost enables our clients to avoid these problems which regretfully culminated in a removal cost of 1 million dollars for the builder.