REMEDIATION OF RCC DAM SEEPAGEUPPER STILLWATER DAM REHABILITATION – PHASE I

摘要

Since the time of initial construction a series of cracks have developed through thernUpper Stillwater Dam structure extending from the upstream face to the downstream face andrnvertically from the crest to the underlying bedrock foundation. A remediation program wasrnimplemented consisting of chemical grouting and for certain locations installing a membranernliner across the crack plane extending from the top of the dam into the underlying bedrock.rnThe Upper Stillwater Dam Rehabilitation Project is unique primarily in the manner employed tornconstruct the membrane slots, each 14-ft. long with a minimum opening width of 4.5 inches torndepths of 158-ft, 182-ft, and 240-ft. respectively, as well as the design and implementation ofrnthe stainless steel membrane systems. Construction of a typical slot consisted of drilling arnseries of overlapping drill holes using a percussion drilling system modified with a unique guidernsystem. An initial pilot hole was core drilled to the depth of the slot followed with a percussionrndrilling system fitted with a special guide sleeve designed to follow the profile of eachrnsequential slot hole to ensure a high degree of verticality and bearing alignment with adjacentrnslot holes. The corrugated stainless steel membrane was designed for expansion based onrnthe total movement of the crack throughout the seasonal temperature cycles. Finally, thernupstream and downstream annular spaces of the slot-membrane are back-filled with a specialrnhot asphalt/portland cement mixture specifically designed for adhesion to stainless steel andrnconcrete, resilience, and expansion properties.