Nevada Water Science Center


Aquifer Tests

Contact Information

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

 

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

 

Nevada Water Science Center
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Middle Carson River Basin

Primary Investigator: Doug Maurer

Well Data

USGS Site ID
Local Name Altitude Uppermost
Opening
Lowermost
Opening
Primary Aquifer Hydraulic
Conductivity
(ft/d)
390941119425901 5th&PasW 4613 50 70 ALLUVIAL FILL 25
391615119164801 Adrian1 4235 15 20 VOLCANIC ROCKS 50
391252119160201 Adrian2 4279 19 24 ALLUVIAL FILL 300
391928119285901 Borda 4405 110 140 VOLCANIC ROCKS .72
391727119190701 Bull Canyon 4251 36 41 ALLUVIAL FILL 2
391456119345801 CR-1 4342 25 35 ALLUVIAL FILL 63
391457119343801 CR-2 4341 26 36 ALLUVIAL FILL 98
391937119281801 Divide Deep 4490 227 265 VOLCANIC ROCKS .62
391937119281701 Divide Shallow 4468 142 162 VOLCANIC ROCKS .057
391615119345501 DV Parkway 4365 63 83 ALLUVIAL FILL 2
391023119422101 GC P-2 4591 5 20 ALLUVIAL FILL 59
391024119425801 GC-P3 4611 10 25 ALLUVIAL FILL 22
391729119294501 Eureka 4284 22 32 ALLUVIAL FILL 160
391756119310101 F.C. 4339 70 90 ALLUVIAL FILL 3.2
391655119330901 Hiway 50 4352 76 96 ALLUVIAL FILL 110
391522119330501 House 4360 71 91 ALLUVIAL FILL 50
391454119335501 L.S.-4 4357 35 55 ALLUVIAL FILL 8
392003119224901 misfits 4267 52 6677 ALLUVIAL FILL 5.1
391802119300001 Pine 4304 40 60 ALLUVIAL FILL 66
391545119333901 R-1 4315 20 30 ALLUVIAL FILL 37
391605119331901 R-2 4308 20 30 ALLUVIAL FILL 69
391625119324801 R-3 4304 18 28 ALLUVIAL FILL 47
391638119321001 R-4 4304 25 35 ALLUVIAL FILL 16
391604119322001 R-5 4353 80 100 ALLUVIAL FILL 110
391632119314101 R-6 4348 70 90 ALLUVIAL FILL 38
391649119313702 RA-2 4300 145 165 ALLUVIAL FILL 97
391703119311701 RA-3 4292 5 15 ALLUVIAL FILL 140
391711119303301 RA-4 4289 4 14 ALLUVIAL FILL 120
391758119321001 Ring 4358 64 84 ALLUVIAL FILL 1.2
391529119314101 S. Sutro 4351 70 90 ALLUVIAL FILL .96
391416119351401 Vet 4355 25 35 ALLUVIAL FILL 62

 

Aquifer Test

All Aquifer Test Files (zip)

Middle Carson River Basin

Slug Tests (pdf)

Introduction

Slug tests were conducted in 31 wells in the Dayton Valley Hydrographic Area, Nevada (Figure 1). The tests were conducted to estimate the distribution of aquifer characteristics in the middle Carson River basin in support of a study being conducted in cooperation with the Bureau of Reclamation (project # 9705-D29BE). Results of the slug tests will aid in the development of a numerical ground-water flow model of the Middle Carson River basin. The model will be used to evaluate potential effects of groundwater pumping on streamflow of the Carson River. For this reason, many of the tests were made in wells in the Carson River flood plain and adjacent to the river. Hydraulic conductivities of gravel, sand and gravel, sand, sand and clay, decomposed granite, and fractured volcanic rock were estimated.

 

Site

The slug tests occurred in wells that were screened across gravel, sand, clay, and fractured volcanic rock intervals between 5 to 300 ft below land surface (Table 1, Drillers Logs). All sites were 2-inch, PVC observation wells with either schedule-40 or schedule-80 casing. About 80 percent of the screened intervals were completed in sand and gravel, sand, or sand and clay. Three screened intervals were completed in fractured volcanic rock, two wells were completed in gravel, and one was completed in decomposed granite.

 

Location of wells for slug tests in Middle Carson River area, NV
Figure 1— Location of wells for slug tests in Middle Carson River area, NV

Procedures

The slug tests consisted of single or multiple falling-head and rising-head tests. The tests were made by quickly lowering a PVC cylinder beneath the static water level and recording the resulting rise and decline in water level back to static; often called a falling-head test. Next the cylinder was quickly raised above the static water level and the resulting water-level drop and rise back to static was recorded; often called a rising-head test. The cylinder was sealed at both ends and filled with sand. Cylinder dimensions were either 1.5-inch in diameter by 3.5 ft long or 1.25-inch in diameter by 5 ft long for slugging 2-inch wells with either schedule 40 or 80 casing, respectively. Water levels were recorded at uniform intervals of 0.1 to 5 seconds and were measured with a vented Global transducer (Model WL16, SN 093797303, 0-15 ft range, accuracy ±0.1% of full scale).

Between 1 and 6 slug responses were observed in each well. A single response was analyzed where 90-percent recovery occurred in less than 10 seconds or more than 10 minutes. Clean responses were difficult to induce where recovery was rapid. Long recovery times logistically prohibited multiple slug tests in a well.

 

Analysis

Slug tests were analyzed using analytical solutions coded in spreadsheet software (Halford and Kuniansky, 2002). Slug-test responses that did not oscillate were analyzed using Bouwer and Rice (1976). Water-level recovery in well Divide Deep was typical (Figure 3) of the 21 non-oscillatory responses. Water levels clearly oscillated during six of the slug tests (Figure 4) and were analyzed using the method of Butler and Garnett (2000) which is an analytical approximation of underdamped through overdamped water-level responses. The slug-test response in the Divide-Shallow well was analyzed with the Cooper-Greene method (Cooper and others, 1967; Greene and Shapiro, 1995). Water-level measurements, analyses, and results from all tests are summarized in the file 00_Maurer_MiddleCarsonRiverNV-SlugTestReport.xlsx.

Hydraulic Property Estimates

Hydraulic conductivity estimates ranged between 1 and 160 ft/d and averaged 60 ft/d in sand and gravel, sand, and sand and clay (Table 1). The hydraulic conductivities of the gravels were 50 and 300 ft/d. Hydraulic conductivities of the fractured volcanic rocks were all less than 1 ft/d.

 

Normalized water-level recovery in well Divide Deep and estimated slope.

Figure 2— Normalized water-level recovery in well Divide Deep and estimated slope.

 

Normalized water-level recoveries in well Highway 50 that were analyzed using Butler and Garnett (2000).

Figure 3— Normalized water-level recoveries in well Highway 50 that were analyzed using Butler and Garnett (2000).

 

Table 1— Site identifiers, well construction, lithology, and hydraulic conductivity estimates for the Dayton Valley Hydrographic Area, Nevada

Normalized water-level recoveries in well Highway 50 that were analyzed using Butler and Garnett (2000).

 

References

Bouwer, Herman and Rice, R.C., 1976, A slug test for determining hydraulic conductivity of unconfined aquifers with completely or partially penetrating wells: Water Resources Research 12(3), p. 423—428.

Butler, J.J., Jr., and E.J. Garnett, 2000, Simple procedures for analysis of slug tests in formations of high hydraulic conductivity using spreadsheet and scientific graphics software: Kansas Geological Survey Open-File Report 2000-40, http://www.kgs.ku.edu/Hydro/Publications/OFR00_40/index.html

Cooper, H.H.Jr, Bredehoeft, J.D., and Papadopulos, I.S., 1967, Response of a finite-diameter well to an instantaneous charge of water: Water Resources Research, v. 3, p. 263-269.

Greene, E.A., and Shapiro, A.M., 1995, Methods of conducting air-pressurized slug tests and computation of type curves for estimating transmissivity and storage: Ground Water, v. 36, no. 2, p. 373-376.

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://pubs.usgs.gov/of/2002/ofr02197/

 

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