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Hydraulics Lab: 2005-2006

La Cueva Channel Debris Removal Structure

 

INTRODUCTION

The purpose of this study was to determine a way to remove the debris from the La Cueva Arroyo before it discharges into the North Diversion Channel. Due to space limitations, a full size sedimentation pond cannot be used; so alternative BMP’s (Best Management Practices) will be analyzed. Structural BMP’s that are hydraulically driven, easy to maintain, and contain little or no grating will be preferable.

 

 

Figure 1: La Cueva Site Layout (Balloon Fiesta Park is to the North)

 

 

OPTION 1: REVERSE FLOW DEBRIS FILTER

 

Full modeling report

 

SUMMARY

The Reverse Flow Debris Filter (RFDF) creates dead zones by reversing the flows so that water flowing through the structure can only leave by a certain path. Floating and neutrally buoyant material would be removed because the upper portion of water cannot pass through the structure, though any dense material would be swept out. The maximum flow rate that the structure would treat is around 150 cfs. With the 1:12 scale model, testing was completed using a number of different scenarios.

 

RECOMMENDATIONS

The addition of a horizontal plate at the end of the ramp created the desired results. The filter removed most of the floatable and neutrally buoyant material, and two linked in series could potentially remove an even higher percentage of the material. Another option is the addition of a grate at the discharge point, which would be possible because most debris will not be carried to the screen, and as the filter drains after use, the water will flow back into the structure and self clean.

 

 

OPTION 2: FLOATING DEBRIS BOOM

 

SUMMARY

The floating debris boom (previously modeled in Year 15) was placed on-site at the North Pino Arroyo for testing. There is currently a debris intake structure located in the channel that diverts debris into a baffle weir debris removal structure. The debris boom was built out of rope and ‘noodles’ (a pool toy shaped like a noodle made out of foam). A number of different configurations were tested, including long and short booms, as well as between 5 and 12 noodles per boom section. 

 

  

 Figure 2: On-site testing of floating boom.

 

RECOMMENDATIONS

The testing of the floating booms on-site was not completed. The absence of suitable storm flows during the testing period led to a lack of data regarding the suitability of booms. One observation made during testing was that the booms would roll as water flowed underneath, which would allow trapped debris to pass down the channel. Most channels in the Albuquerque area are super-critical, but the floating boom seems to work best in a sub-critical channel. The high velocities can damage the structure and reduce the debris removing effectiveness.