Tulameen River Coanda screen weir design for the town of Princeton, BC
Description
The purpose of this report was to research and design a run-of-the-river weir structure for the Town of Princeton, British Columbia.
Although the scenario is fictitious in nature, the project was based on a situation that could one day be at the forefront of a small town’s proposal for a bid on a design. The purpose of this project was to assess the viability of a weir structure for the generation of hydro-electric power and thus increase the delivery of green energy for a burgeoning industrial and residential population.
_________________, my industry sponsor, supported the concept behind this project and believes it to be a good exercise in academic research.
My project was limited to the study of the weir design structure and did not include additional research into the hydro-electric facility.
River analysis was undertaken using data taken from Gauge Station 08NL024 near Princeton and a potential site location for the weir structure was located. Using Manning’s Equation and local topography, the river’s cross sections, discharge rates and varying depths were all evaluated.
Using the Gumbel Method, a 100-year return was extrapolated and a maximum peak discharge of 650 m3/s was calculated. This predicted value was then used to design the height of the wing walls of the weir structure.
The Standard Step Method was used to calculate the backwater profile curve and to determine an acceptable distance of gradually varied flow. This information was then used to design the height of the backwall of the structure. An overall concrete structure was then drafted with Autodesk
software using these input parameters. Based on the average discharge rate of the river, the Ogee Spillway formula was used to
optimize the weir’s width, calculated at approximately 70m.
A soil mechanics analysis was performed on the midspan of the structure to determine the factor of safety against uplift forces and overturning moments. Both factors of safety were deemed acceptable based on the quantity and configuration of concrete used.
The Coanda screen design for this project was based largely in part from experimental data taken from the United States Department of the Interior. Based on the calculated average river discharge, an Ogee crest was designed along with an accelerator drop plate and optimal Coanda
screen configuration (length, tilt, curvature, etc.).
Based on the relative topography of the area, a tentative location for a powerhouse was selected and an ideal power output was calculated. The results of that output classify this structure as meeting a mini-station qualification.
All relevant calculations, drawings and schematics have been included in the body of the report or in an appropriate appendix as required.
Further considerations for this project would be additional research into sediment control, studying the effects of a 200-year return flood on the weir structure and exploring ways to increase the potential power output.