Building on Shaky Ground: the Danger of Constructing Homes on Landfill
When we hear the word “landfill,” most of us think of a designated site where waste is disposed of and buried. However, a landfill may also refer to ground that has been filled in with rocks and sand or soil rather than waste materials, so that it can be used for a specific purpose, such as building houses. If these landfills are not properly stabilized, a large earthquake could cause severe shaking or liquefaction of the ground in such areas, and major damage to the structures located on and around the landfill.
Landfills & Soil Liquefaction
Liquefaction occurs when saturated soil substantially loses strength and stiffness because of a sudden, applied stress, such as an earthquake, causing it to behave like a liquid. Soil that is not compact, such as loose landfill dirt, is much more likely to experience liquefaction than dense soil. This is because loose soil will compress, or cave in on itself like quicksand, when a load is applied, while dense soil will actually expand.
Building codes require engineers to consider the effects of soil liquefaction in the design of new buildings, bridges, and dams, as the devastating consequences of building on potentially unstable areas of landfill have been confirmed. For example, the Marina District neighborhood in San Francisco is constructed almost entirely on landfill comprised of mud, sand, and rubble from the 1906 earthquake. In 1989, the Loma Prieta earthquake caused severe liquefaction of the landfill upon which the neighborhood was built, resulting in major damage including a small firestorm. More recently, liquefaction was largely responsible for extensive damage to residential properties during the 2010 and 2011 New Zealand earthquakes.
Builders & Developers Must Adequately Prepare Ground for Building
Generally, construction defect liability is based on the decisions that a builder or developer makes, such as choosing a safe place to build and making sure the land, or landfill, is properly stabilized. In other words, before breaking ground, builders and developers must ready the ground they plan to break. If builders and/or developers fail in this responsibility, they may be liable for resulting damages.
Construction Defect Expert Witness
Professionals in the construction and development industries have a duty to follow building codes and prevent building issues and construction defects as much as possible. If you need an expert to advise you or appear as a witness in a case involving building code compliance or structural hazards, please contact Engineering Expert Witnesses for a free initial consultation. Pierre Handl, P.E. evaluates disasters in California and nationwide to identify their cause and determine whether design or construction played a role in the catastrophe.