Nevada Water Science Center


Aquifer Tests

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Phil Gardner
Groundwater Specialist
Phone: (775) 887-7664
Email:pgardner@usgs.gov

 

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Nevada Water Science Center
2730 N. Deer Run Rd.
Carson City, NV 89701

 

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Big Springs Southwest Well

Primary Investigator: Keith Halford

Well Data

USGS Site ID
Local Name Altitude Uppermost
Opening
Lowermost
Opening
Primary Aquifer Transmissivity
(ft2/d)
384112114091101 Big Springs SW 6020 500 700 CARBONATE ROCKS 4000

 

Aquifer Test

All Aquifer Test Files (zip)

Big Springs NW

Aquifer Test (pdf) || Groundwater levels (NWISweb)

 

A single-well aquifer test was conducted by the U.S. Geological Survey (USGS) in southwestern Snake Valley, HA195, near Great Basin National Park to estimate the transmissivity of the carbonate-rock aquifer (BS-SW; Figure 1). Well BS-SW was pumped for about 48 hours at 170 gpm between 14:28 November 2, 2010 and 13:48 November 4, 2010 and discharge was measured with a totalizing flowmeter. Transmissivity from the well BS-SW aquifer test will help characterize flow to Big Springs, southern Snake Valley, Nevada.

 

Site and Geology

The aquifer test occurred in southwestern Snake Valley where groundwater development has been proposed (Welch and others, 2007). Basin-fill deposits were encountered from land surface to 215 ft below land surface. Fractured carbonate-rocks were encountered between 215 and 700 ft below land surface. Significant water-bearing intervals occurred between 500 and 700 ft below land surface. Depth to water in the completed well was about 355 ft below land surface. Thickness of the permeable carbonate rocks is unknown.



Figure 1. Location of wells BS-NW and BS-SW and Big Springs gages, BS-NC and BS-SC, in Snake Valley, Nevada as referenced to North American Datum of 1983 (NAD 83).


Table 1. Well location and construction data for wells near Big Springs, southwestern Snake Valley, Nevada.


[Latitude and longitude are in degrees, minutes, and seconds and referenced to North American Datum of 1983 (NAD 83); ft amsl, feet above North American Vertical Datum of 1988 (NAVD 88); ft bgs, feet below ground surface; na, not available.]

Map Identifier

SITE IDENTIFIER

Latitude

Longitude

Ground surface elevation, ft amsl

Depth to Static Water Level, ft bgs

Diameter Screen, in inches

Top Screen, ft bgs

Bottom Screen, ft bgs

BS-NW

384227114082701

38°42'27"

114°08'27"

5,815

228

8

300

460

 

BS-SW

384112114091101

38°41'12"

114°09'11"

6,020

355

8

500

700

 

BS-NC

102432241

38°41'58"

114°07'52"

5,571

na

na

na

na

 

BS-SC

10243224

38°41'57"

114°07'52"

5,571

na

na

na

na

 


Water Levels and Drawdowns

Water levels were measured in well BS-SW (Figure 2). Water levels in well BS-SW were 356 feet below land surface, prior to pumping. Water levels were monitored a few weeks prior to the BS-SW aquifer test and during the test. The monitoring period was prolonged so pumping effects could be differentiated from barometric changes, tidal fluctuations, and seasonal declines.



Figure 2. Water-level changes in well BS-SW between October 1, 2010 and November 4, 2010.


Drawdowns in well BS-SW were estimated by subtracting the water level prior to pumping from measured water levels. The water-level modeling technique (Halford, 2006) was not applied because environmental fluctuations of 0.1 ft were diurnal and seasonal declines were less than 0.01 ft during the 48-hr test.

 

Analysis

The estimated transmissivity of the carbonate-rock aquifer was 4,000 ft2/d (Figure 3). Drawdowns in well BS-SW were interpreted with the Cooper-Jacob method (Cooper and Jacob, 1946) as implemented by Halford and Kuniansky (2002). Drawdowns exhibited a confined response for the duration of the aquifer test. The full thickness of the carbonate-rock aquifer likely was investigated because the aquifer is confined (Halford and others, 2006).

 


Figure 3. Drawdowns and straight-line approximation in well BS-SW during 48-hour aquifer test.


References

Cooper, H.H., and C.E. Jacob. 1946. A generalized graphical method for evaluating formation constants and summarizing well field history. American Geophysical Union Transactions 27: 526-534.

Halford, K.J., and Kuniansky, E.L., 2002, Spreadsheets for the analysis of aquifer-test and slug-test data, version 1.1: U.S. Geological Survey Open-File Report 02-197, 51 p., http://water.usgs.gov/pubs/of/ofr02197/

Halford, K.J., 2006, Documentation of a spreadsheet for time-series analysis and drawdown estimation: U.S. Geological Survey Scientific Investigations Report 2006-5024, 38 p.

Halford, K.J., W. D. Weight, and R. P. Schreiber 2006, Interpretation of Transmissivity Estimates from Single-Well, Pumping Aquifer Tests, Ground Water, v. 44 no. 3, 467-471

Theis, C.V., 1935, The relation between the lowering of the piezometric surface and the rate and duration of discharge of a well using groundwater storage: Am. Geophys. Union Trans., vol. 16, pp. 519-524.

Welch, A.H., Bright, D.J., and Knochenmus, L.A., 2007, Water resources of the Basin and Range carbonate-rock aquifer system, White Pine County, Nevada, and adjacent areas in Nevada and Utah: U.S. Geological Survey Scientific Investigations Report 2007-5261, 96 p.

 

 

 

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