Urban geology of boulder, colorado: A progress report

A cooperative program in urban geology between the city of Boulder, Colorado, and the Department of Geological Sciences, University of Colorado, has been in effect since late 1969. The principal geological problems in the rapidly growing urban environment of Boulder include: 1. Swelling clays in the Pierre Shale have been related to foundation failure, pavement heaving, and landsliding on hillslopes. 2. Colluvium and ancient landslides have been made unstable by removal of support, by loading with buildings or fill, and by increases over natural moisture contents through lawn watering and septic-tank seepage. 3. Flooding on high-gradient mountain streams has been caused by sedimentation induced by the constriction of natural channels through urban development. In May, 1969, Bear Canyon Creek overflowed its banks with a discharge of less than one-fifth its design capacity. Flooding was caused by coarse bedload deposited upstream from a culvert. The Boulder city geologist collects data on soils exposed in open excavations within the city, maps ancient and modern landslides, provides information for contractors bidding on public works projects, and reviews the geologic aspects of all consulting work prepared for the city. Examples of formats used for the communication of information to responsible city officials include geotechnic maps of all open cuts, street pavement design maps, and input into the city-wide standard specifications for enginnering projects.