TC3 to TC1! Could Nemean do this for your site?

We recently had a client approach us for a second opinion on the results of their soils analysis. They had been advised their site was a TC3 land classification.  For context the classifications are as follows.

Technical Category 1: Future land damage from liquefaction is unlikely. You can use standard foundations for concrete slabs or timber floors.

Technical Category 2: Minor to moderate land damage from liquefaction is possible in future significant earthquakes. You can use standard timber piled foundations for houses with lightweight cladding and roofing and suspended timber floors or enhanced concrete foundations such as a waffle slab/Ribraft foundation.

Technical Category 3: Moderate to significant land damage from liquefaction is possible in future significant earthquakes. Site-specific geotechnical investigation and specific engineering foundation design is required. There is no one-size-fits-all solution for homes in Technical Category 3 (TC3) that require repairs to foundations or need to be rebuilt. Foundations designed for homes in TC3 will be site specific and may involve deep foundation piles.

Rather than accepting the previous assessment at face value, our team decided to take a more thorough approach and take a second look. It appeared that the assessment had taken limited information and resources to make ultra-conservative assumptions.

Our comprehensive investigation revealed something the client was thrilled to hear – the majority of the site satisfied all the criteria for TC1 classification. The soil contained significantly higher percentages of non-liquefiable material than initially reported, and the liquefiable layers were deeper than critical thresholds for residential construction.

With our detailed analysis and supporting evidence, we were able to successfully reclassify the land as TC1.

This means a considerable saving to our client as they can use standard foundation designs.

This is not always going to be the case, but it illustrates our company motto.

Problem Solved.