Journal of Cold Regions Engineering

The objectives of this study were to determine effective vegetation species that had the ability and efficiency to improve the effluent quality of an existing wastewater wetland treatment system. Channels were constructed down the length of one cell of the existing wetland trough and planted with the selected plant materials, which included bullrushes (Scirpus validus) and arrowhead (Sagitarria latifolia). Removal efficiencies for ${\mathrm{BOD}}_5$, total suspended solids (TSS), and ammonia‐nitrogen were monitored and shown to be influenced more significantly by hydraulic retention times than the presence of introduced vegetation. However, when retention times were adequate, removal efficiencies did reach similar levels as those documented by other researchers using these plant species.

Two different models were used to simulate the influence of commercial vessels transiting narrow‐cross‐sectional channels in the presence and absence of ice. Models were developed by two contracted groups using hydraulic principles. These models were calibrated for local conditions using measurements of effects of vessel passage conducted during the ice‐on and open‐water navigation seasons. Results of model simulations compared well with verification data from vessel passages. Model simulations provided valuable information to assess potential impacts of navigation during ice‐on periods.

Channel curvature and the presence of bridge piers, which may effectively subdivide the channel, affect the ice-conveyance ability of curved and sinuous rivers and may favor the initiation of ice jams. Preliminary results from laboratory experiments conducted in a small-scale, sinuous channel with polyurethane blocks simulating ice floes indicate that deleterious effects of bridge crossings on ice conveyance in sinuous rivers can be minimized by locating bridges at the apex of bends, rather than along straight reaches between consecutive bends. Experiments were performed with two sizes of polyurethane blocks for a channel with a rectangular cross section and for a channel provided with a cross slope at the bends' apexes. Two different bridge-pier spacings were tested. The results presented in this paper are only indicative of the general trend in ice-conveyance behavior for bridge piers in curved channels. Additional experiments are recommended before extrapolating this conclusion to field conditions.