|Home||Archived February 20, 2019||(i)|
Drilling Monitoring Wells in Dry Tortugas National ParkFahrenheit 100, Blue Sky, Blue Water, Crumbling Bricks, and Here Comes Hurricane Charley
On August 3, the U.S. Geological Survey (USGS) Florida Integrated Science Centers (FISC) drill team, consisting of geologists Don Hickey and Gene Shinn, microbiologist Dale Griffin, and hydrologist Ann Tihansky, cranked up their hydraulic drill in the moat of a Civil War-era fort. They were drilling in the water-filled moat surrounding historic Fort Jefferson at Dry Tortugas National Park, some 65 miles west of Key West, FL. The heavy equipment had been transported from Key West to the remote park on the National Park Service's supply boat, the motor vessel Fort Jefferson. The team lived for a week aboard the research vessel Papa-San anchored in the harbor.
The project, funded by the USGS Biological Support in National Parks program, is designed to (1) monitor fecal pollutants and nutrients in the carbonate-island water lens underlying historic Fort Jefferson, (2) determine the island's geologic framework, and (3) determine annual fluctuations in the ephemeral freshwater lens. Pollutants in the ground and surface water are suspected to be influencing surrounding coral reefs.
The first and most grueling step of the 2-year project was the installation of 10 monitoring wells in midsummer heat. Eight wells were core drilled to 18-ft depth and screened. Core drilling allows core samples to be recovered from the hole for later analysis. Screening entails putting a piece of polyvinyl chloride (PVC) pipe down the hole, with a cap at the bottom and fine slits cut through the lower section of the pipe, so that water but not sand can enter the pipe for sampling. A ninth well was cored to 46-ft depth and screened, and the tenth was cored to a depth of 62 ft below sea level. The last well penetrated pre-Holocene coral at 55-ft depth.
As the last well was being drilled, tension was buildingHurricane Charley was on the way. The group headed for Key West to avoid the storm's projected path. Sure enough, the eye of Hurricane Charley passed directly over Fort Jefferson on August 12, causing considerable damage and forcing the park to close. The wells are reported to be undamaged. During the next 2 years, the wells and surface waters in the surrounding anchorage and camping area will be monitored every 3 months for fecal coliforms, nutrients, and salinity. Tough duty, but someone has to do it.
For those who have never heard of Dry Tortugas, it is the site of the largest Civil War-era red-brick fort. The fort was never completed. Rifled cannon made such forts obsolete, and construction was halted. Fort Jefferson has had many functions. It served as a jail. Its most famous prisoner was Dr. Mudd, the doctor who set the leg of John Wilkes Booth after he shot Abraham Lincoln. The fort also served as a coaling station for ships before the turn of the century and was the last stop for the U.S. battleship Maine before it blew up in Havana Harbor.
Today the fort is visited daily by two fast catamarans that each disgorge about 100 tourists. A constant stream of pontoon seaplanes arrives from Key West every hour or two. Visitors also arrive by private boat, and campers occupy the small camping area and swimming beach outside the fort. The adjacent island is famous for its sooty terns that land and breed on the island after returning from their annual migration to Africa. In recent months, there has been a new form of landingabout 65 Cuban refugees recently arrived in the middle of the night. It is a place with a rich historical past and an interesting future. An $8-million reconstruction project to replace bricks has just begun. The National Park Service is looking for volunteer bricklayers. Any takers?
in this issue:
Drilling Monitoring Wells in the Dry Tortugas
|Home||Archived February 20, 2019|