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Bradys Hot Springs (Springer's, Fernley) (updated 2003)

The hot springs along U.S. Highway I-80 about 32 km northeast of Fernley have been referred to as Hot Springs, or Bradys, Springer's or Fernley Hot Springs, and are the Emigrant Springs of the Forty-Mile Desert. Bradys is currently the accepted name of the area. Some early travelers called it the Spring of False Hope. Coming across the desert, the oxen of the wagon trains could smell the moisture before reaching the springs. However, when they rushed forward to drink, they found the water scalding. The emigrants collected water in casks to cool, but pushed on to the Truckee River, as there was no forage at the springs (Work Projects Administration, 1940).

In the 1880s Russell (1885) reported that hot boiling water issued from a number of orifices, and when these became obstructed, the steam escaped with a hissing and roaring sound. During this same period, there was an unsuccessful attempt to separate boric acid from the waters. In later years the hot water was used in a bathhouse and swimming pool that were located at a service station along U.S. Highway 40. The concrete pool, built in 1929, is all that remains today. The pool was apparently supplied by hot water directly from the springs. The hot springs do not flow at the surface today, although abundant steam vents can be seen on cool mornings from the Highway

Bradys Hot Springs are located in NE¼ NE¼ SW¼ Sec. 12, T22N, R26E. Thermal groundwater is found within an area of 15.5 to 20.5 km² centered on this location (figure). The elongate thermal area is parallel to the "Thermal Fault" mapped by Anctil and others (1960). Areas of hydrothermal alteration are aligned along this fault, and its trace has also been outlined by areas of observed snowmelt, indicating warm ground (Olmsted and others, 1975, fig. 37). This fault has had recent movement, as it cuts spring sinter and the alluvial fan deposits in the spring area and to the north. The fault is normal and dips steeply to the west, with the downthrown side to the west (Olmsted and others, 1975). All successful steam wells were collared in the hanging wall of the Brady Thermal Fault (Anctil and others, 1960).

The rocks exposed in the vicinity of Bradys consist of Tertiary basalt and andesite, Tertiary sedimentary rocks, Pleistocene lake sediments, and Quaternary alluvial deposits and siliceous sinter (figure and figure).The geology of the area is further discussed by Faulds and others (2002.

Bailey and Phoenix (1944, p. 51) reported the presence of cinnabar and sulfur in Sec. 6(?), T22N, R27E about 0.4 km southeast of U.S. Highway 40 and 0.8 km east of the hot springs. The best showings of cinnabar are reported from around an active hot-spring vent. The occurrence is in hydrothermally altered tuff. Soil gas in the vicinity of the main Thermal Fault and around active steam vents at Bradys is anomalous in mercury (John Robbins, Scintrex Limited, written commun., 1973).

The spring sinter at Bradys is predominantly opal, and is quite extensive. It is concentrated along the main Thermal Fault and a small subsidiary fault to the east (Oesterling and Anctil, 1962).The groundwater in Fireball Valley (Hot Springs Flat) to the north probably moves as underflow to Bradys Hot Springs, and other groundwater may move as underflow from the Fernley area (Harrill, 1970). Olmsted and others (1975) suggested that the recharge of the thermal area could be outside the local drainage area.

Groundwater discharge from the thermal area is in part by evapotranspiration and in part by lateral subsurface outflow toward the south. Prior to the drilling of geothermal wells in the late 1950s and early 1960s (but after diversion of the flow to a swimming pool), White (written commun., 1974, in Olmsted and others, 1975) estimated a spring flow of about 78 L/min. Waring (1965) reported a larger flow (190 L/min.), but White believed that this may be too large. The withdrawal of water during drilling may have caused the springs to cease flowing (Harrill, 1970) and at present all discharge is in the subsurface. The original spring was 82°C (Oesterling, 1962). Boiling water reportedly stands at 6 m below the surface in one well (Willden and Speed, 1974, p. 55).

Twelve major geothermal wells had been drilled at Bradys Hot Springs prior to 1979, ranging in depth from 104 to 2,218 m. The temperatures encountered during drilling were up to 214°C, (Koenig, 1971). Following the drilling of Magma Power Co. Brady No. 2 well in 1959, thermal activity spread along the 5-km part of the main fault. This fumarole activity was probably due to the draw down of cooler, near-surface groundwater to deeper areas of hotter rock. A similar line of fumaroles developed after a well blow out in 1978, and they are observed today along the Brady fault due to drawdown during production. Olmsted and others (1975) describe the 1959 activity in more detail from data in a 1960 unpublished report by Allen. Tests on several wells shortly after drilling indicated 77,000 to 317,000 kg/hr of fluid. The well head pressure was 0.6 to 1.3 kg/cm²) gage (psig) (Middleton, undated report). The steam flashover was reported to be 5% (Koenig, 1971). Calcite formed rapidly in the well bores during flow, requiring reaming of the wells after a short period of time. However, the amount of scaling was reported to decrease after the wells have been produced for some time (Oesterling, 1962). The thermal water at Bradys is of the sodium chloride type, with total dissolved solids from some steam wells reported to be over 2,400 ppm. The silica concentration from a steam well near C Sec. 12, T22N, R26E (Harrill, 1970) indicates a reservoir temperature of about 182°C (Olmsted and others, 1975). This seems somewhat low in view of a 204°C down-hole temperature reported (Welch and Preissler, 1986). In 1977, Geothermal Food Processors, Inc. of Reno, Nevada received a $2,836,800 federally guaranteed loan to construct a geothermal food dehydration plant at Bradys, which is still operational today.

Following exploration drilling in the 1980s, Bradys double flash power plant came on line in 1992, producing 21 MW from a 186°C resource. Bradys recently added a 5-MW binary Ormat Energy Conversion unit (OEC) that uses pentane as the working fluid. Plant construction began in May 2002 and was completed in August 2002. The geothermal production wells at Bradys (seven in 2002) produce from depths of 300 to 1,800 m in permeable zones in Tertiary volcanic rocks (Oligocene? and Miocene pyroclastic rocks) in the hanging wall of the Bradys fault, a steeply dipping, north-northeast-striking fault with down-to-the-northwest normal displacement. Left lateral strike-slip offset is also possible, as the fault is apparently continuous with a possible drag fold about 7 km to the northeast (Stewart and Perkins, 1999). The stratigraphic displacement (throw) on the fault is believed to be about 150 m (Benoit and others, 1982, p. 8), and northwest-striking cross faults and hanging-wall faults parallel to the Bradys fault may control fluid flow. Mesozoic metamorphic rocks were penetrated at depth in the low permeability footwall block, where temperatures up to 210°C are reported (Robertson-Tait and Lovekin, 2000). The plant was purchased by ORMAT Nevada, Inc. in July 2001(GeothermEx, 2004).

Bradys Hot Springs Map

Chemistry