C150314 Feasibility Study - Laserfiche WebLink

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Feasibilitc Shide Farmers' High Line Canal and Reservoir Company October 2010 Ralston Creek Siphon The ii�let structure has erosion to the headwall exposing the joint between the wall and box culvert in the east ai7d west cell of the approach channel. The exposed joint and other cracks observed in the stn�cture will require repair to prevent continued stn�ctural degradation. We did not observe a sigiuficant amount of soil loss or settlement around the inlet structure. Since the majority of the damage can be repaired with surface treatments, we recommend instituting the repairs to the ii�let structure outlined below. The outlet structure has structural displacement and settlement in addition to erosion causing extensive surface damage to the walls. The integrity of the structure is anticipated to continue to degrade with the increased rislc that the sidewalls will collapse due to settlement and cracicing. The steel block out in the west sidewall is at risk of n�sting through allowing bacicfill to dump into the outlet stn�cture. Because of the expense to repair the surface damage, the displacement and settleinent of the side walls, and replacing the block out, we recommend instituting the repairs to the outlet structure outlined below. The repairs to the inlet would include: ■ Reinoval of woody vegetation around the structure ■ Cleaning of areas with surface damage ■ liistallation of steel dowels to supplement existing corroded steel ■ liistallation of cementitious patch primer ■ Installation of high strenbth shotcrete or hand trowelled patch material Recommended repair actions for the outlet structure include: Removal of woody vegetation around the structure Construction of a new outlet structure including: - Headwall - Sloping apron to canal invert - Sidewalls - Divider wall - Transition walls to canal banlc - Downstream riprap revetment canal stabilization Figures illustrating the repairs required at tlus struct�ire can be found in Appendix B-4. Burlin�ton Northern Railroad Siphon The overall condition of the structure was adequate to inaintain performance. The area immediately downstream of the structure is experiencing some erosion and should be repairecl to maintain serviceability of the structure in years to come. Figures illustrating the areas of repair at this stn�cture are presented in Appendix B-5. -12-