Characteristics of waterlogged western red cedar and western hemlock wood : implications for the salvage of timber from the Kinbasket reservoir in B.C.
Samples of western hemlock [Tsuga heterophylla (Raf.) Sarg.] and western red cedar [Thuja plicata Donn] trees completely submerged standing in a fresh water reservoir for approximately 24 years were examined in terms of relative wood density, extractives content in cedar and mechanical properties of small clear specimens. Due to diameter limitations in the sample material, test results for modulus of elasticity (MOE) in compression parallel-to-the-grain were found to be unreliable, but could be expected to compare to published values in a like manner as other test results. Based on the results of tests for wood density, extractives content and strength properties of small clears, the sound wood quality of submerged western hemlock and western red cedar is comparable to that of these species in general. Mitigating these favourable results, however, were the low proportion of sound logs recovered, external checking of log surfaces, and fine shake observed in red cedar which could have a negative impact on appearance grades. Definite determination of submerged wood quality would require sawing of logs, and evaluation of lumber yield and properties, and long-term tests for durability of the red cedar.