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
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Carson City, NV 89701

 

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Bridgeport Well Hunewill2

Primary Investigator:

Well Data

USGS Site ID
Local Name Altitude (ft) Uppermost
Opening (ft)
Lowermost
Opening (ft)
Primary Aquifer Transmissivity
(ft2/d)
381239119165601 Hunewill2 6552 70 90 ALLUVIAL FILL 1400

 

Aquifer Test

All Aquifer Test Files (zip)

Well Hunewill2

Aquifer Test (pdf)

Introduction

Since 2004, the U.S. Geological Survey (USGS) has maintained a comprehensive hydrologic database and monitoring network in the Walker River Basin. The monitoring of hydrologic data continues to support a variety of scientific investigations within the Walker River Basin and provides important hydrologic data to the Walker Basin Restoration Program, local irrigation districts, Federal Water Master, Walker River Paiute Tribe, and the public.

An improved understanding of the groundwater system in the Walker River Basin is a critical component of these ongoing investigations. Continuous water-table monitoring and single-well aquifer tests of select wells were needed to parameterize a groundwater flow model being developed to evaluate the influence of various water transfer scenarios on local groundwater conditions. These water transfer scenarios are part of a larger effort by the Walker Basin Restoration Program to restore environmental flows in the Walker River and to Walker Lake. To better understand the seasonable variability of groundwater elevations and aquifer responses to groundwater pumping, a series of aquifer tests in the alluvial aquifer were performed between (1/26/2016 to 9/18/2016). Drawdown or recovery from domestic and municipal pumping during this monitoring period were used to estimate hydraulic properties of the alluvial-fill aquifer. This memorandum documents the data and analysis of aquifer tests from monitored wells as part of this study in Bridgeport Valley (fig. 1).

 

Location map of well AT-2

Figure 1. Location of the Bridgeport wells.

Sites and Geology

Bridgeport Valley is a 75 square-mile basin located in the eastern Sierra Nevada mountain range (fig. 1). Agriculture fields used for cattle grazing dominate the valley, and surface water diversions from Buckeye and Robinson Creek and the East Walker River are used for flood irrigation. Groundwater is the principal source of drinking water in the valley, with domestic and municipal wells penetrating a Pliocene to Holocene alluvial-fill aquifer (fig. 1). Permissions were obtained to monitor and complete aquifer tests in five wells in Bridgeport Valley (fig. 1). Tests were performed on four domestic wells with 6 to 8 inch diameter casing and 10 to 20 ft screen intervals and on one municipal well with a multiple 16- to 30-inch diameter casing and a 210 ft screen interval (table 1).

Table 1. Monitoring well coordinates, construction, and aquifer description, Bridgeport Valley, Mono County, California.

 

USGS Site ID Latitude (NAD83) Longitude (NAD83) Altitude (ft) Casing Size (inches) Uppermost Opening (ft) Lowermost Opening (ft) Primary Aquifer
381510119140001 38.252778 -119.23333 6,471 16 to 30 75 285 Alluvial Fill
381302119183401 38.217100 -119.30932 6,752 6 78 98 Alluvial Fill
381754119125101 38.298389 -119.21416 6,495 6 50 70 Alluvial Fill
381407119132401 38.235281 -119.22327 6,510 8 5 15 Alluvial Fill
381239119165601 38.210919 -119.28216 6,552 8 70 90 Alluvial Fill

 

Test Procedures

Single-well constant-rate pumping aquifer tests were performed on four wells, three tests were competed by using existing submersible pumps in wells 381510119140001, 381302119183401, and 381754119125101, and a temporary submersible pump was installed for use in well 381407119132401. In the three wells with existing pumps, tests were conducted by opportunistically analyzing drawdown or recovery of water levels that occur due to regular pumping. Pumping discharge was measured volumetrically (using a calibrated bucket and stopwatch) at the domestic wells and was determined from metered data for the municipal well. The measured time-rate of drawdown for the average pumping rate for each test was analyzed using the Cooper-Jacob drawdown or recovery straight-line method (Cooper and Jacob, 1946). Detailed descriptions of the aquifer pumping tests are as follows:

Site 381510119140001 is a 16 to 30-inch multiple-diameter municipal well. Drillers log report 775771 indicates the borehole penetrates alternating intervals of fine to coarse sand to 400 feet below land surface (bls). The static water level was about 12 feet bls. The well is pumped on a daily interval at an average rate of 860 gallons per minute (gpm) for the City of Bridgeport’s municipal supply. Water-level changes were recorded with an electronic recording pressure transducer set at a 2-minute measurement frequency. A pumping interval beginning on 1/26/2016 from 05:56 to 07:08 and producing a drawdown of 60 feet was selected for the aquifer test period. Drawdown was analyzed by the Cooper-Jacob drawdown straight-line method (Cooper and Jacob, 1946).

Site 381302119183401 is a 6-inch diameter domestic well. Drillers log report 163000 indicates the well penetrates alternating intervals of sand and gravel to a depth of 98 feet bls. The static water level was about 40 feet bls. An existing submersible pump was used for the single day pumping test on 8/20/2016. The average flow rate of the pump was 7.6 gpm. Water-level changes were recorded with an electronic recording pressure transducer set at a one-minute measurement frequency. Pumping began on 8/20/2016 at 13:52 and continued until 13:58 producing a drawdown of approximately 20 feet. Pumping was ceased quickly to prevent the water level dropping below the pump level and the well was allowed to recover for 3 hours. Water-level recovery data were analyzed by the Cooper-Jacob straight-line method (Cooper and Jacob, 1946).

Site 381754119125101 is a 6-inch diameter domestic well. A drillers log report was not available for the well, however well log 931758 (900 feet south of the site) indicates the well likely penetrates alternating intervals of clay and gravel to a sounded depth of 70 feet bls. The static water level was about 45 feet bls. The well services a house and was pumped daily by a submersible pump. The existing submersible pump was used for the single day pump test conducted on 7/13/2016. The average flow rate of the pump during the test was 7.1 gpm.Water-level changes were recorded with an electronic recording pressure transducer set at a one-second measurement frequency. Pumping began on 7/13/2016 at 15:33 and continued until 15:37 producing a drawdown of approximately 7 feet. The well was allowed to recover for 3 hours. Water-level recovery data were analyzed by the Cooper-Jacob straight-line method (Cooper and Jacob, 1946).

Site 381407119132401 is a shallow 8-inch diameter domestic well completed within a 10-inch diameter borehole. Drillers log report was unavailable, though well log 735343 (1,500 feet away) indicates the well likely penetrates alternating intervals of sand, gravel, mixed with clay to a depth of 15 feet bls. The static water level was about 4 feet bls. The well was not actively used and did not have a pump deployed in the well. An aquifer test was performed on 7/14/2016 with a submersible pump temporarily deployed in the well. The average flow rate of the pump during the test was 25 gpm. Water-level changes were recorded with an electronic recording pressure transducer set at a one-second measurement frequency. Pumping started on 7/14/2016 at 9:53:58 and ended at 9:55:01. Water-level recovery were analyzed by the Cooper- Jacob straight-line method (Cooper and Jacob, 1946).

A slug test was performed on one well by rapidly pouring a known volume of water into well 381239119165601. This procedure was used because the 8-in well cap was not removable, limiting the size of the opening to a 1-inch port in the well cap. The poured slug test was performed as follows:

Site 381239119165601 is an 8-inch diameter well that is screened between 70 and 90 feet bls in coarse sand and gravel. The static water level was about 7 feet bls. Three separate poured slug tests were performed in the well on 7/13/2016. For each slug test, 10 gallons of water were rapidly poured into the well casing. Water-level changes were recorded with an electronic recording pressure transducer set at a 0.5-second measurement frequency. The near instantaneous rise and subsequent fall of the water-level in response to the poured slugs were recorded and analyzed as a falling head test using the Bouwer and Rice method as described by Halford and Kuniansky (2002).

Aquifer Test Results

Transmissivity values for the alluvial-fill material ranged between 50 and 1,400 feet2/day (table 2) for the five tests. Water-level data and the Cooper-Jacob and slug analysis of test data are available in figures 2 and 3, respectively. Aquifer material surrounding the screened intervals of the wells were obtained from the respective well driller’s reports or from reports of nearby wells, which only provided general descriptions of the lithology.

 

Table 2. Aquifer test results for the alluvial aquifer in Bridgeport Valley, Mono County, California.

 

USGS site ID Aquifer test Aquifer material description Transmissivity (feet2/day)
381510119140001 Constant-rate pumping (drawdown) Fine to coarse sand 1,300
381302119183401 Constant-rate pumping (recovery) Silt, clay, and fine sand 50
381754119125101 Constant-rate pumping (recovery) Clay with gravel 50
381407119132401 Constant-rate pumping (recovery) Sand with gravel and clay 1,400
381239119165601 Slug, falling-head Coarse sand to gravel 1,400

 

References

Bouwer, Herman, 1978, Groundwater Hydrology: New York, McGraw-Hill, 480 p.

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.

Cunningham, W.L., and Schalk, C.W., comps., 2011, Groundwater technical procedures of the U.S. Geological Survey: U.S. Geological Survey Techniques and Methods 1-A1, 151 p.

Domenico, P.A. and Schwartz, F.W., 1990, Physical and Chemical Hydrogeology: New York, John Wiley and Sons, 824 p.

Halford, K.J., and Kuniansky, E.L., 2002, Documentation of spreadsheets for the analysis of aquifer-test and slug-test data: U.S. Geological Survey Open-File Report 02-197, 51 p.

Water-level measurements from the pumping tests Water-level measurements from the pumping tests

Fig. 2. Water-level measurements from the pumping tests A, 38151011914001, B, 381302119183401, C, 381754119125101, D, 381407119132401, and the poured slug tests E, 381239119165601

 

Aquifer test results from the Cooper-Jacob analysis of single-well pumping test at wells

Fig. 3. Aquifer test results from the Cooper-Jacob analysis of single-well pumping test at wells A, 38151011914001, B, 381302119183401, C, 381754119125101, D, 381407119132401, and slug test analysis of three poured slug tests at well E, 381239119165601. Where the x-axis (time, dimensionless) represents time since production started divided by time since production started minus time production stopped.

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