The first Laramie Energy Technology Center steam flood experiment in a Utah Tar Sand, LETC TS-1S, was conducted in the Northwest Asphalt Ridge deposit located near Vernal, Utah. Following completion of construction n April 1980, steam injection was initiated in the center well of two concentric inverted five spot patterns. The zone chosen for the experiment was a 45 foot (14 m) thick sandstone in the Rimrock Member of the Mesavarda Formation. The pattern area was 0.25 acres (1012 m^2) and contained a 12k API (986 kd/m^3) bitumen with a viscosity greater than 10^6 cantipoise (10^3 Pa.s) at reservoir conditions. The average oil saturation was 8.9 percent of the pore volume. During the 160 days of operation, 65,700 barrels (10.4 dem^3) of water equivalent steam were injected at 360 to 530 peig (2.5 to 3.7 MPa) and 180 to 650 BPD (29 to 103 m^3/d). Total production during the test amounted to 1,150 barrels (183 m^3) of oil and 6,250 barrels (994 m^3) of water.