Hydrogeology of the Piney Point-Nanjemoy, Aquia, and Upper Patapsco aquifers, Naval Air Station Patuxent River and Webster Outlying Field, St. Marys County, Maryland, 2000–06

Abstract

Patuxent River and Webster Outlying Field ranges from approximately 620 to 680 feet below the North American Vertical Datum of 1988. The potentiometric surface of the Upper Patapsco aquifer near Naval Air Station Patuxent River and Webster Outlying Field has been declining at a rate of about 2 feet per year for the past several years. Aquifer testing indicates the transmissivity of the aquifer is about 2,100 to 3,900 feet squared per day. Water samples collected from the Upper Patapsco aquifer at Naval Air Station Patuxent River and Webster Outlying Field in 2000 and 2001 met all Federal drinking-water standards.

Groundwater quality and occurrence and distribution of selected constituents in the Aquia and Upper Patapsco aquifers, Naval Air Station Patuxent River, St. Mary's County, Maryland, July 2008

“…The Aquia aquifer (table 1) is a deep, confined aquifer consisting of greenish-black quartz sand, glauconite, and lenses of clay and shell beds of the Aquia Formation (Chapelle and Drummond, 1983). The elevation of the top of the Aquia aquifer is approximately -450 ft (feet) relative to the North American Vertical Datum of 1988 (NAVD 88) beneath NAS Patuxent River and WOLF (Klohe and Feehley, 2001), and the thickness of the aquifer decreases from about 100 to 145 ft at NAS Patuxent River to about 50 ft at WOLF (Klohe and Kay, 2007).…”

“…The Upper Patapsco aquifer is a deep, confined aquifer which underlies the Aquia aquifer and consists of sand units interbedded with silt and clay units and is part of the Patapsco Formation of the Potomac Group (Klohe and Kay, 2007). The elevation of the top of the Upper Patapsco aquifer is approximately -660 ft NAVD 88 at well SM Df 100 ( fig.…”

“…At WOLF, the levels of some constituents in the Aquia aquifer were still within the range of values expected for freshwater, but were slightly higher than levels in the Aquia aquifer at NAS Patuxent River, which may indicate the very early stages of saltwater intrusion at WOLF (Klohe and Feehley, 2001). Klohe and Kay, 2007). Klohe and Kay (2007) described water quality for two wells screened in the Upper Patapsco aquifer.…”

“…Klohe and Kay, 2007). Klohe and Kay (2007) described water quality for two wells screened in the Upper Patapsco aquifer. On the basis of samples collected from the two wells, they found that the groundwater in the Upper Patapsco aquifer is sodium-bicarbonate type.…”

“…Groundwater samples were collected from wells screened in the Aquia and Upper Patapsco aquifers to describe the general water chemistry of these aquifers. The data were compared with data presented in previous USGS and MGS investigations (Bennett, 1944;Chapelle and Drummond, 1983;Klohe and Feehley, 2001;Klohe and Kay, 2007) to determine if water quality had changed over time in the aquifers. Sample data also were used to describe the occurrence and distribution of arsenic and tungsten, and the status of saltwater intrusion at NAS Patuxent River and WOLF.…”