On November 14, 2013, a sinkhole forced more families out of their homes in Dunedin, Florida.
Michael and Janie Dupre’s home was swallowed by a sinkhole early Thursday morning; however, the Dupres were aware of the sinkhole activity and already began remediating the condition before their home collapsed. The Dupres reported their sinkhole loss claim to Citizens Property Insurance Corporation. Citizens’ retained engineering company, HSA Engineers and Scientists, tested the home and confirmed sinkhole activity. HSA provided a grout only stabilization program. The Dupres obtained a second engineering opinion that included underpinning to stabilize the building. The carrier refused to pay for any repair other than the grouting program recommended by HSA.
Just forty-eight hours after the commencement of the grouting program, the Dupres’ home collapsed.
This incident is an opportunity for me to explain "preventative underpinning,” because it could have prevented this potentially tragic event.
Underpinning can be utilized to lift structures to repair structural damage to buildings. Another common use for underpinning is referred to as bypass underpinning. Bypass underpinning is utilized to bypass a problematic shallow soil zone beneath a structure like shallow clay, organics, and/or fill.
Finally, preventative underpinning is also commonly recommended. The purpose of preventative underpinning is to prevent additional damages from occurring to the structure during the grouting process. Why? Because before a property is grouted, long metal poles are drilled deep into the ground around the entire structure potentially aggravating the sinkhole.
Combine weak shallow soil and active raveling from sinkhole activity and you have a serious problem. Under these circumstances, engineers commonly recommend underpinning the structure before grouting is implemented.
This recent sinkhole event is an example of why preventative underpinning is recommended. If the structure was stabilized before the grouting, maybe the Dupres’ would still be safe in their home.