How a Directional Drilled River Crossing Water Main Saved Significant Permitting Requirements, Construction Time, and Money, Aroostook River, Caribou, Maine

This paper sets out an assessment of the value and practicality of the construction of fossil fired generating plant designed and built as single units and includes a proposal for the design and layout of a single unit designed to maximize the benefits derived from this concept. The conclusion is that an acceptable design of power plant, based on the construction of single 600 MW units, can be developed for the UK system which could prove to be advantageous in construction time, in capital cost and in running cost. The layout applies equally effectively to large ‘green field’ sites or for replanting existing stations; in addition, the plant can be replicated in detail and thereby reduce design and engineering costs. Finally the layout can also be applied in principle to smaller units for overseas utilities as required by their system developments.

Download Full-text

Difficulties and modifications in the use of available methods for hydraulic conductivity measurements in highly clogged horizontal subsurface flow constructed wetlands

Water Science & Technology ◽

10.2166/wst.2017.340 ◽

2017 ◽

Vol 76 (7) ◽

pp. 1666-1675 ◽

Cited By ~ 6

Author(s):

Mateus Pimentel Matos ◽

André Baxter Barreto ◽

Gabriel Rodrigues Vasconcellos ◽

Antonio Teixeira Matos ◽

Gustavo Ferreira Simões ◽

...

Keyword(s):

Hydraulic Conductivity ◽

Constructed Wetlands ◽

Subsurface Flow ◽

The Other ◽

Good Representation ◽

Horizontal Distance ◽

Conductivity Measurements ◽

Construction Time ◽

Horizontal Subsurface Flow ◽

Subsurface Flow Constructed Wetlands

Despite the fact that several authors consider the available measurement methods of hydraulic conductivity (ks) suitable for a good representation of the bed condition and clogging potential in horizontal subsurface flow constructed wetlands, others have questioned their adequacy. In this work, hydraulic conductivity measurements with conventional and modified methods were undertaken in two small full-scale units, one planted with cattail (Typha latifolia) and the other unplanted. Both units had already been operating for seven years and showed a high degree of clogging. It was observed that the use of the falling head method, with the introduction of the tubes during the test, provided results without a clear spatial trend. On the other hand, tests done on monitoring wells inserted during construction time showed, as expected, ks increasing with the horizontal distance from the inlet, but without reflecting actual field conditions. It was observed that, as the bed became more clogged, the use of the reported methods became more complex, suggesting the need of other methodologies. The use of planted fixed reactors (removable baskets installed in the bed) with evaluation of ks at constant head in the laboratory showed potential for the characterization of the hydrodynamic properties of the porous medium.

Download Full-text