Complex dewatering project at mixed-use development

As available lands become scarcer, underground parking becomes more and more appealing, especially in growing urban areas like Boulder. Additionally, city planners and developers desire to maintain views and not block sunlight, which are more advantages of underground parking. For these reasons, South-ern Land Company chose to build two levels of subterranean parking beneath the entire...

With the excavation extending well beyond the limits of a traditional vacuum wellpoint dewatering system, and the anticipated flow rates exceeding that of an ejector-well dewatering system, TerraFirma chose to rely on closely spaced, large-diameter deepwell dewatering wells as the primary means of controlling the groundwater. The deepwell dewatering wells were installed from ground surface, just...

TerraFirma’s dewater plan also included the installation of strategically placed portable sump wells within the excavation to supplement the deepwell dewatering wells. These were a very necessary component due to the excavation extending below the bedrock-alluvium interface, according to Leonard. The portable sump wells were used to handle perched and trapped groundwater within the...

From the deepwells, the ground-water was directed to Boulder’s left-hand ditch, directly adjacent to the site. However, as is true of many construction sites along Denver’s front range, the preliminary geo-technical and environmental sampling reports revealed groundwater that was contaminated.

TerraFirma Earth Technologies’ President David Giles holds a Bachelor of Science in Geology from Iowa State University and 33 years of experience in developing and implementing design-build solutions for construction dewatering and groundwater control using deep wells, wellpoints, and ejector systems. Based in Houston, Texas, United States, TerraFirma also has offices in Denver,...