SMALL DIAMETER TBM/PIPEJACKING | TRENCHLESS


Above, figure 11: Elevation on east trough, northern field wall Successful integration and collaboration was


required in the initial stages of detailed design to enable seamless construction of all elements.


CONCRETE TRENCHES The existing structure is a low point in the area with an invert of 4.9m AOD. As the flood waters can flow both ways, the invert level had to be maintained for the new pipe culverts and troughs. Where minimal retention was required, ditches were used to continue the flow of water. Figure 8 shows the proposed works. The colour


scheme comprises: black as the existing structures; red is the new permanent structure; and magenta is temporary works.


FLOOD MODELLING As the structure is within a flood zone, a consent application was required to infill the existing brick


culvert structure and construct its replacement. The Environment Agency requested three culverts and also a full scheme flood modelling, including changes to three nearby culverts within the River Wharfe Floodplain. The model reviewed land measuring 275km2


in order to


understand how the area will be affected more widely. Flood depths of up to 2.5m have been recorded outside of the River Wharfe. Aecom undertook the flood modelling exercise to


support the consent application. The direction from the Environment Agency was to retain the current situation of flood management in the area as closely as possible. This led to several requirements for the detailed design, including confirmation of the cross-sectional area required for the culverts and the materials of the trenches. Sensitivity analysis during the flood modelling


concluded that there would be no increase to flood risks at any vulnerable receptors.


Above, figure 12: Reinforcement for thrust wall September 2024 | 15


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