Florida Sinkholes: Science and Policy

1. Sinkholes in Florida: An Introduction

1 Sinkholes in Florida An Introduction In the winter of 2013 a horrific sinkhole took the life of Jeffrey Bush in Seffner , Florida. He was resting in bed when the ground collapsed under his bedroom. His family rushed in to find just a mattress remaining in the hole where his room once was. Jeffrey was gone forever. One minute he was a vibrant , living human being, and in an instant the earth gave way. This tragedy is unusual. Loss of life to sinkhole formation is a rare occurrence, but sinkhole collapses are not. In 1993, a large sinkhole opened up on the campus of the University of South Florida in a practice soccer field. Although it didn’t make the local news, students, staff, and faculty talked about the presence of the sinkhole on campus and speculated about the overall stability of buildings in the vicinity . The sinkhole, which was 20 feet deep and 15 feet in diameter with vertical walls, formed in the late afternoon, just as daytime students were leaving campus and evening students were arriving. The curious went to look at the sinkhole shortly after it formed, and some brave students jumped into the hole and carved their names in the loose sand on the walls. The next day, the hole was filled and the turf on the field repaired. The sinkhole no longer existed. Shortly after this episode, many students, staff, and faculty began to notice a number of large cracks in some of the older buildings on campus. Few could tell if they were new or if they had formed some time ago. Could the buildings fall into a hole like the one that had formed in the soccer field? Due to the concerns of university people, crack monitors were set on the walls of some of the buildings to determine if the fissures were growing larger. Months later, when it became apparent the cracks were not expanding, the monitors were removed and eventually people on campus forgot about the sinkhole in the soccer field and lost their fear of building collapse (figure 1.1). Florida Sinkholes: Science and Policy 2 This sinkhole episode is similar to others that have played out with varying degrees of severity across the state. In Orlando, a sinkhole opened in a mall parking lot to reveal a cavern. During the construction of a large expressway in the Tampa Bay area, a large supporting pier sank 30 feet into a depression . While sleeping at night, a Winter Park woman woke to strange noises and looked out a window to see a sycamore tree disappear into a giant hole. Within a short time, her house followed. In Spring Hill, a foundation cracked from subsurface sinkhole activity, suddenly making a home uninhabitable. These examples represent just a handful of the hundreds and hundreds of sinkholes that occur each year in Florida. Most of the holes are quite small and do not cause significant damage. However, in many areas of the state, sinkholes are all-too-regular events that reduce property values, damage structures , and create headaches for property owners. Figure 1.1. On February 28, 2013, a sinkhole opened behind the Bush residence in Seffner, Florida, that took the life of Jeffrey Bush. On May 22, 2013, when this image was taken, neighboring homes were being demolished due to extensive damage from the collapse. Hundreds of sinkholes form each year in Florida, but rarely do they cause injury or death. Sinkholes in Florida: An Introduction 3 Although there are many excellent studies of specific Florida sinkholes, no one to date has put together a book detailing what is broadly known about sinkholes in the state. The purpose of this book is to provide a comprehensive review of sinkhole science and policy in the state of Florida. The topic has received much attention in what is called gray literature, or technical documents , written by consulting firms or by federal, state, and local governments. In addition, several conferences sponsored by the Florida Sinkhole Research Institute in the 1980s and the early 1990s produced excellent volumes of proceedings that remain invaluable sources. There are also many important articles on sinkholes in peer-reviewed journals and books. If I have neglected any particular source of information in this book, I certainly regret the oversight. I hope, however, that the book provides an accurate representation of what is currently known about Florida sinkholes. I believe...