Journal of Cold Regions Engineering

Ice scouring poses a significant threat to underwater pipelines for offshore oil production facilities in ice-infested waters. For most locations, the only options against this hazard are to protect the pipeline by trenching, burial, or creative alignment. The optimal burial depths along the length of a pipeline are usually selected on the basis of a hazard model that describes the recurrence rate and severity of scouring along its length. Although sufficient data at a specific site are rarely available to accurately estimate the hazard model, several thousand scours have been documented over extended regions and can provide an estimate of scouring hazards at preliminary stages of design. The main features of the proposed model are a parametrization of the scouring hazard model as a function of water depth and exposure to the ice environment, and the propagation of uncertainties due to model incompleteness and sample size. The proposed model can be validated or readjusted at later stages of the project as more site-specific data become available. The application of the proposed model is demonstrated for the determination of the optimal burial depth for a hypothetical pipeline route.

Lagoon treatment is a common wastewater-treatment option for small communities. In cold regions the design and use of lagoons must consider some unique concerns that impact performance due to cold climates. Many of the concerns can be met by the use of intermittent-discharge lagoons. Presented is a study of intermittent-discharge lagoons in Alberta, Canada. The performance and factors influencing performance were determined by analysis of a large database of effluent quality. Effluent quality was compared to other treatment alternatives. In addition, public concerns and costs involved with lagoon treatment were determined through a survey and compared to other treatment alternatives. The existing data demonstrate that properly designed intermittent-discharge lagoons are capable of producing effluent quality that is superior to the effluent produced by the mechanical treatment facilities in the same region. The survey of operators showed that the vast majority of lagoon facilities do not receive complaints, and the costs of lagoon treatment are shown to be generally more cost-effective than other treatment alternatives.

To date there is virtually no information on the behavior of flowthrough rockfill structures in subzero temperatures. This paper presents new insights into this behavior through consideration of the results of laboratory experiments and by systematically quantifying the relevant heat fluxes that might occur in nature. By applying an order-of-magnitude analysis to a fictitious prototype, it is shown that the viscous dissipation of hydraulic energy is sufficient to prevent internal ice clogging in all but very extreme climatic conditions. This dissipation of hydraulic energy did not, however, prevent surficial ice growth on model dams functioning at around −10°C to −15°C in the laboratory. An approximate degree-day–based ice-growth coefficient is presented and the reasonableness of this coefficient is discussed. An example calculation is used to illustrate the steps that might be involved in a typical heat-budget computation for such flowthrough structures.

This paper describes field and laboratory measurements of the evolving physical and mechanical properties of first-year sea ice through a growth season. The primary objectives were to (1) examine sample size effects on the in situ strength and constitutive behavior; (2) improve understanding of the interrelations between physical and mechanical properties; and (3) verify models based on small-scale isothermal behavior. Replicate sets of observations were made at a site in Elson Lagoon, near Barrow, Alaska, covering fall, midwinter and spring conditions. Each set consisted of in situ fracture, creep, creep recovery, and cyclic loading experiments and laboratory measurements of flexural strength along with a complete description of the physical properties. In situ experiments employed square double cantilever beam specimens ranging in size from 0.25 m to 30 m. Electromagnetic and acoustic emissions generated by fracturing were monitored. Small-scale isothermal laboratory experiments were performed to profile the flexural strength of the sheet. The paper details the size range and loading conditions for the in situ tests and references separate publications for more detailed accounts of the experiments.