Abstract

The Bureau of Land Management (BLM) conducted a bore-hole drilling program on the Bonneville Salt Flats in October 2003 to obtain current salt-crust thickness measurements for comparison with 1988 thickness measurements previously made by BLM. A total of 69 bore holes were drilled, and two different measurement methods were compared in 55 of the 69 bore holes (BLM mud auger and Utah State Department of Highways UDOT pole). Differences in accuracy and precision between the two methods were analyzed, and we determined that the mud-auger method produced more reliable measurements. Salt-crust volumes were computed from 1988 and 2003 thickness measurements and their respective salt-crust boundaries to see if measurable changes could be observed.

We concluded from our analysis of the 1988 and 2003 measurements and their respective calculated volumes that 1) salt-crust volumes determined by the 2003 mud auger measurements were 7% larger than those determined by the 2003 UDOT pole measurements, 2) there was virtually no difference between salt-crust volumes determined by the 1988 and 2003 pole measurements, and 3) the Laydown Project produced no measurable change in salt crust thickness, but did help maintain the ion mass balance in the shallow-brine aquifer, which contributes to maintenance of the existing salt-crust volume.