USGS Georgia Water Science Center
This report is available online in pdf format (2 MB): USGS SIR 2004-5295 (
)
Michael F. Peck, Keith W. McFadden, and David C. Leeth
U.S. Geological Survey Scientific Investigations Report 2004-5295; 36 pages (Published February 2005) ONLINE ONLY
During October 2002, the Durango Paper Company (formerly Gillman Paper Company) in St. Marys, Georgia, shutdown paper-mill operations; the shutdown resulted in decreased ground-water withdrawal in Camden County by 35.6 million gallons per day. The decrease in withdrawal resulted in water-level rise in wells completed in the Floridan aquifer system and the overlying surficial and Brunswick aquifer
systems; many wells in the St. Marys area flowed for the first time since the mill began operations during 1941.
Pumping at the mill resulted in the development of a cone of depression that coalesced with a larger adjacent cone of depression at Fernandina Beach, Florida. Since closure of the mill, the cone at St. Marys is no longer present, although the cone still exists at Fernandina Beach, Florida. Historical water-level data from the production wells at the mill indicate that the pumping water level ranged from 68 to 235 feet (ft) below North American Vertical Datum of 1988 (NAVD 88) and averaged about 114 ft when the mill was operating. Since the shutdown, it is estimated that water levels at the mill have risen about 140 ft and are now at about 30 ft above NAVD 88. The water-level rise in wells in outlying areas in Camden County was less pronounced and ranged from about 5 to 10 ft above NAVD 88. Because of the regional upward water-level trend in the Upper Floridan aquifer that started during 1999–2000 in most of the coastal area, combined with a steeper upward trend beginning during October 2002, it was not possible to determine if the 5–10 ft rise in water levels in wells away from St. Marys was due to the mill closure. In addition to water-level rise of 22–26 ft in the Floridan aquifer system, water-level rises in the overlying surficial and Brunswick aquifer systems at St. Marys after the shutdown indicate upward leakage of water. Water levels had stabilized in the confined surficial and Upper and Lower Floridan aquifers by April–May 2003; however, the water level in the upper Brunswick aquifer was still rising as of May 2003.
Chloride concentrations in the Upper Floridan aquifer in Camden County do not exceed the State and Federal drinking-water standard of 250 milligrams per liter (mg/L). With the exception of three wells located at St. Marys, all of the wells sampled during this study (from September 2002 to May 2003) had chloride concentrations ranging from 30 to 50 mg/L, which are considered within background levels for the Upper Floridan aquifer in this area. The three wells—two at the Durango Paper Company and the other an old unused City of St. Marys well—had chloride concentrations that ranged from 74 to 175 mg/L, which are above the background level, but were still below the 250-mg/L drinking-water standard. The source has not been determined for the elevated chloride concentration in these wells; the chloride concentration in one of the wells has decreased slightly since the paper-mill shutdown. Chloride concentrations throughout Camden County showed little change after the paper-mill shutdown.
Abstract
Introduction
Purpose and Scope
Description of the Study Area
Hydrogeologic Framework
Methods of Investigation
Previous Investigations
Well-Numbering System
Acknowledgments
Ground-Water Withdrawal
Ground-Water Levels
Confined Surficial Aquifer
Upper Brunswick Aquifer
Floridan Aquifer System
Upper Floridan Aquifer
Lower Floridan Aquifer
Interaquifer Leakage
Chloride Concentrations in Camden County
Summary and Conclusions
Selected References
This report is available online in pdf format (2 MB): USGS SIR 2004-5295 ()
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