Fiducial tags can be recognised successfully and decoded by computer vision systems in order to produce location information. We term a system dependable if its observable results are predictable and repeatable. The dependability of such a vision system is fundamentally dependent on the scheme used to encode data on the tag. We show that the rotational symmetry common to many tag designs requires particular consideration in order to understand the performance of the coding schemes when errors occur. We develop an abstract representation of tags carrying symbolic data which allows existing information coding techniques to achieve robust codes. An error-correcting coding scheme is presented for carrying arbitrary symbolic data in a dependable vision system.

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Site investigations at an oil and gas facility identified a highly acidic waste referred to as residual acid tar that resulted in the transport of dissolved nickel toward the point of compliance at concentrations that exceeded site environmental screening levels. Solidification/stabilization (S/S) via deep soil mixing was selected as the remedial approach and a mixture of ground granulated blast furnace slag cement and Portland cement was subjected to treatability testing to evaluate the reagent mix's ability to achieve treatment objectives. Results from the treatability test showed a cement mix dose of 21 percent was sufficient to raise the pH above the target of 6.0 and reduce dissolved nickel concentrations to below site screening levels in leachate from treated samples of residual acid tar and material impacted by residual acid tar. Cement mix doses of 21 percent or greater were sufficient to achieve target strengths in the unimpacted shallow overburden. However, none of the doses tested were able to achieve target strengths in the residual acid tar or peaty material impacted by the residual acid tar. Results showed soil strengths increased significantly when the pH in leachate from the treated samples approached 12, suggesting the presence of organic acids related to the peaty soils may interfere with the cement set. Recommendations from the study include additional treatability testing to evaluate pre‐treatment with hydrated lime to satisfy acid neutralization requirements prior to dosing with the cement mix. ©2016 Wiley Periodicals, Inc.