When I picked up the old photo in an Antique shop in Albany I was immediate struck by hpw the suspension bridge supporting a water pipe across a river could be the one across the American River to the Zantgraf mine built in 1899. But upon closer inspection, and studying a companion photo, this suspension bridge was at another site in California. My research indicates that the suspension bridge was built to deliver water to a 1930’s hydraulic mining operations on the east side of the South Fork of the Trinity river, just south of the confluence of the South Fork and main Trinity River in Salyer, CA. (See: Anderson Island and Zantgraf Mine Hike for the American River water pipe suspension bridge.) Click image to enlarge.
Suspension bridge at Salyer over Campbell Creek
The similarities between the remnants of the Zantgraf mine suspension bridge and the Salyer Bridge were striking. A water ditch above the bridge crossing supplied water to the pipe line. On the south side of Campbell creek was a tall bridge abutment to support the suspension cable towers. The Salyer Bridge terminates on the north side of the Campbell creek where the cable towers appear to be resting on a cut in the hillside. It’s possible that both the Salyer Bridge and the Zantgraf Mine Bridge were both designed and constructed by Andrew Hallidie of the A.S. Hallidie & Co. in San Francisco.
Water and electricity
From a description of the suspension bridge across Campbell creek I learned that the pipe was 42 inches in diameter, nearly twice the size of what I suspect was the Zantgraf mines 24 inch pipe. The CALIFORNIA JOURNAL OF MINES AND GEOLOGY report the described the water supply for the Salyer Mining Company indicates that the suspension bridge was in place by at least 1931. In 1939, the water works was then owned by the Swanson Mining Corporation who put in a power plant, using the falling water to generate electricity. View excerpts from the Journal at end of post.
Hydro plant to pump water for hydraulic mining
The Swanson Mining water diversion made news throughout the country for their use of the water to generate power to pump it back up the hill.
Use Water Power to Pump Water For Gold Mines
Sacramento, Cal. – Acclaimed by the state division of mines to be the only operation of its kind in California, a unique hydraulic mining system in which the water supply is used to generate power to pump water to higher levels, is used by a Trinity County, Cal, mining concern.
A few miles from Salyer, up the Campbell creek, the Swanson mining corporation has built an intake plant which pumps water up a series of hills to the mine, several miles from the creek.
The water supply system is a perpetual motion scheme in that two eclectic pumps lift water up several hinder feet of hills, while the water rushing down from the heights runs through a hydroelectric plant to furnish power for the pump motors.
Thus the water is pumped to the scene of mining operations with its force utilized to wash clay, san and gravel into sluices where the gold is recovered.
Present operations are uncovering gold flakes, gold dust and small quantities of platinum.
Sawyer decision didn’t stop hydraulic mining in California
The Mines and Geology report also notes another suspension bridge that was employed to convey the water over the South Fork of the Trinity River up to the placer deposits being mined. This was a hydraulic mining operation. Hydraulic mining had been stopped in the Sierra foothills and mountains by the Sawyer decision of 1884. But the judicial decision didn’t apply to hydraulic mining operations whose debris didn’t wash into the Sacramento central valley threatening farming operations. Consequently, many hydraulic mining operations along the Trinity River system continued into the 1940’s. Click thumbnails to enlarge.
Destination: Salyer, CA
The land encompassing the dams, flumes, siphons, suspension bridges, penstocks and power plant were formerly decommissioned as a power producing entity in 1972. While I’m not sure what areas are public or private property, Salyer seems like a good destination to do some hiking and view some of the history of hydraulic mining first hand on a future trip.
Returning Salyer mining land
CALIFORNIA JOURNAL OF MINES AND GEOLOGY
STATE OF CALIFORNIA
DEPARTMENT OF NATURAL RESOURCES
RICHARD SACHSE, Director
DIVISION OF MINES
FERRY BUILDING, SAN FRANCISCO
WALTER W. BRADLEY
Vol. 37 January, 1941 No. 1
Excerpts from the online report for the Salyer and Sawson hydraulic mining and hydro-electric power plant.
Salyer Consolidated Mines Company
Salyer Consolidated Mines Company equipped the property for operation on a large scale as a hydraulic mine. C. M. Salyer of Salyer was president, W. D. Mcintosh was secretary, and D. E. Carleton was general manager. An eight-mile ditch with a stated capacity of 80 cubic feet per second was built to Hennessy Creek. No water was available for this in the season 1930-1931. Water was taken from Campbell Creek in a ditch and two inverted siphons stated to have a capacity of 5000 miner’s inches. Head available on the lower terraces at altitudes of 600 to 800 ft. above sea level was 200 to 350 ft.
During the season, 1930-1931, 300,000 cubic yards of gravel was mined from two pits, one on the Trinity River side of the ridge, the other on the South Fork side. Gold and platinum were recovered in sluices 5 ft. wide and 4 ft. deep with 12-inch wooden blocks for riffles. Sluices had lengths as follows: at the low pit on Trinity River side, 300 ft.; at a pit near the camp on Trinity River side, 1300-ft. altitude(not worked in season 1930-31), 1000 ft.; on the South Fork side, 550 ft. The company did some mining during several subsequent seasons; but for several years the property has been in the hands of Swanson Mining Corporation, which see. Additional equipment has been added by this corporation.
Swanson Mining Company
Swanson Mining Corporation is now in control of the property formerly held by Salver Consolidated Mines Company, which has already been described in this report. A. J. Swanson is president, C. A. Swanson is vice president, and J. B. Blair is secretary-treasurer, Salyer, Trinity County, California. It is a Delaware corporation with eastern offices in care of Rogerson, Clary, and Hewes, Jamestown, New York. Patented property is in Sees. 14, 15, 22, 23, 26, 27, T. 6 N., R. 5 E., H. M.
In order to provide a water-supply for the higher terraces, Swanson Mining Corporation has installed a hydro-electric plant of 2000-hp. rated capacity. Part of the water from Campbell Creek is used to generate power, and part is boosted by pumps to the mine. In 1939, connected load was 1200 hp. Starting at the diversion dam, the water system comprises 1065 ft. of flume, 6 ft. by 4 ft., a siphon of 500 ft. of 54-inch pipe and 300 ft. of 42-inch pipe, the latter being
on a suspension bridge across Campbell Creek, then an open ditch, 7100 ft.in length. From this, 5400 ft. of 42-inch pipe runs to the power house, then 1125 ft. of 42-inch pipe and 350 ft. of 24-inch pipe, the latter being on a suspension bridge across South Fork of Trinity River, continues toward the mine. Following this are 3500 ft. of 30-inch pipe and 500 ft. of 26-inch pipe to no. 1 pump house, then 2400 ft. of 24-inch pipe to no. 2 pump house, then 400 ft. of 24-inch pipe, and 300 ft. of 18-inch pipe to the mine. In the pit, 15-inch pipe is used. The first pump has a 20-inch suction line, and a 16-inch dis- charge line, and is driven by a 600-hp. motor. The head at the power house is 600ft., and the first pump is placed at such an altitude on the side of the canyon that a 60-ft. pressure is maintained on the suction side. This pump boosts the water to the second pump, which is 200ft.higher. The second pump has a 14-inch suction and a 12-inch discharge. It is driven by a 600-hp. motor. Both pumps are single- stage centrifugals. Head maintained in the pit is about 180 ft. Pressure on the discharge side of no. 2 pump is 125 to 135 lb. per square inch. The 2000-hp. alternating current generator is driven by a Pelton wheel. Water right on Campbell Creek calls for 40 cubic feet per second.
The working-pit, excavated mostly during the season, 1938-1939,was roughly 500 ft. long by 300 ft. wide by an average of 50 ft. deep at the time of our visit. The face was 110 ft. high, and was made up largely of sand and clay, said to contain enough gold to pay for handling it. Beneath this was 30 ft. of gravel carrying gold in flat flakes as large as one-eighth of an inch along the edges, also fine gold. Some grains of the size of grains of wheat are recovered. Bedrock consists of alterating bands of slate and schist with steep dips. Bands are each a few feet in width. Two hydraulic giants with 4-inch or 5-inch, sometimes 6-ineh, nozzles were in use. Experiments were being made in blasting down the bank in advance of hydraulicking.
Recovery of gold and platinum is made in a sluice, 360 ft. long, with a grade of three-quarters of an inch to the foot. It is 43 inches wide and 36 inches deep. Riffles are of 45-lb. steel rails set ball down or flat side up, and with this flat side sloping one-half inch to the width of the rail in the opposite direction to the slope of the sluice.
Spaces are iy 2 inches. At the end of the sluice is a grizzley in two sections, 4 ft. and 12 ft. long respectively, made of rails with the ball up, and the flat side cut off. Between these two sections is a section of grizzley made of manganese steel bars, one inch wide on the top and one-half inch wide on the bottom, and six inches deep. Sizes of less than one-half inch pass through the grizzley to undercurrents, which are similar to the tables on a dredge. They are fed by a sluice, in the bottom of which is a screen of steel plate punched with 5/16-inch holes. It is 60 ft. long, 2 ft. wide, and slopes one inch to one foot. Eleven tables, each 4 ft. by 20 ft. are equipped with steel-shod Hungarian riffles. They slope 1% inches to 1 foot. Quicksilver is used in the first two feet.
Tables are arranged so that any one of them can be cleaned up while the others are in service. The concentrate flows in a V-trough to a small pump, which raises it to a trommel, 4 ft. by 2 ft., with a 7-mesh screen. Oversize is discarded. Undersize drops to a hopper, from which it is fed to a two-cell Pan American jig, with cells 12 inches square. Concentrate from the jigs is treated in 300-lb. batches in an amalgamation barrel, 18 inches by 24 inches. Each batch from the barrel is discharged to a metal sluice containing a trap in which are jets of water to keep the sand from packing. About five pounds are saved here from the 300-lb. batch, in which are the amalgam and the platinum-group metals. Rejects still contain some gold coated with secondary pyrite, and these are ground from time to time for additional recovery by placing rods in the amalgamation barrel.
Below the grizzley in the main sluice is an 800-ft. tailing sluice discharging to Trinity River. It is equipped for its entire length with riffles of 35-lb. and 45-lb. steel rails. A tract of mineable gravel of 25 acres has recently been developed by the drilling of 18 holes to average depth of 80 ft. to 90 ft. Maximum depth was 122 ft. A total crew of 25 men work on three shifts. Water is usually available for the full seven-month mining season. In 1938-1939, thirty percent of the season was lost on account of shortage of water.
One ounce of platinum-group metals is recovered to each 20 ounces of gold. An analysis of a shipment follows:
- Platinum 28.0% Iridium 30.8%
- Ruthenium 10.0% Osmium 25.0%
- Waste 6.2%