The Roadford Scheme: Planning, Reservoir Construction and the Environment

Roadford reservoir completes South West Water's major three reservoir strategy quadrupling storage in the region.
The paper examines how environmental issues have impacted on the scheme and demonstrates how effective planning and management can minimize effects and concerns on a major civil engineering project.
Strategy changes from river regulation to gravity water mains have given reduced environmental impact on rivers and a lowering of power costs, also giving environmental gain. The setting of strict environmental protection measures within contracts and a determined policing policy during construction have produced low levels of pollution incidents during construction.
The paper highlights the benefits of working with environmental groups to secure a successful conclusion not only of the construction element but how that construction can be blended into its local environment. Costs are identified and the authors point to the substantial public relations benefits that can be gained with the successful management of environmental issues.     

Crystallization Mechanisms in Glass-Ceramics

Transmission electron microscopy, electron diffraction, and microprobe X-ray analysis were used to study crystallization of glasses in the systems Li₂O-SiO₂, BaO-SiO₂, and Li₂O-A1₂O₃-SO₂. The ternary system, with 4 mol% TiO₂ added to an Li₂O-Al₂O₃-4SiO₂ composition, crystallizes with a simple morphology of equiaxed grains of the β-quartz metastable phase which transforms at higher temperatures to the stable β-spodumene structure. The binary systems exhibit a more complex crystallization morphology dictated by crystal anisotropy, temperature, impurity content, and susceptibility either to intermediate-phase formation (BaO-SiO₂) or to liquid immiscibility (Li₂O-SiO₂). The initial crystal growth units formed in these systems are frequently two-phase branched morphologies many micrometers in diameter. They may be recrystallized to form polycrystalline glass-ceramics with submicrometer grain sizes.