California Gulch-Yak Tunnel
MWW&AI did a reconnaissance-level seismotectonic hazard evaluation for the California Gulch - Yak Tunnel area near Leadville, Lake County, Colorado. The potential earthquake hazards in the area were important in evaluating alternatives for plugging the Yak tunnel, a source of pollution in the upper Arkansas River basin, and in assessing the stability of tailing impoundments in the Leadville mining district. Postulated large magnitude earthquakes and surface fault rupture, if credible, could impose potentially significant limitations on the remedial design.
We reviewed existing geological and seismological reports on the stability of abandoned tailings ponds in the Leadville mining district;we compiled instrumentally-recorded seismicity and historic earthquake reports in the region surrounding California Gulch; we evaluated the potential for seismogenic surface faulting in the project area; and, based on our synthesis of geological and seismological data, we provided estimates of design earthquakes.
|
|
Wyoming State Penitentiary
Wyoming State Penitentiary: A variety of problems apparently related to surface water, ground water and foundation conditions were noted on occupancy of the facility in 1981, leading to a lawsuit against the designers and builders. MWW&AI was engaged to define pre- and post-construction geological/geotechnical conditions across the penitentiary site; to assess the probable impact of those conditions on damage reported to buildings and utility tunnels; and to offer independent, professional opinions regarding the nature and causes of the damage. Along with surface and areal mapping, an extensive subsurface exploration progam was undertaken to assess the issues with water.
|
Siting Study for SteelReservoir Tank
In Henderson, Nevada, MWW&AI was asked to perform geological and geotechnical investigations for On-site Zone 1625 Reservoir (a 6-million gallon steel tank) for the Lake Las Vegas development. To fully evaluate the site and to provide engineering recommendations, we map the site's geology to determine orientation and type of bedrock and geologic structure. We laboratory testing of native materials to develop fill criteria, and did an evaluation of the rock-slope stability.
|
 Brush Cogeneration Project
South of Brush, Morgan County, Colorado: MWW&AI was asked to assess the geotechnical conditions across the site; to develop design criteria for foundations of the cooling tower, turbine generator building, boilers, condensation storage tank, raw/fire water tank and greenhouse water tank and the thermal storage tanks; and to generally assist the Colorado Power Partnership and United Engineers and Constructors in our areas of expertise. Eleven borings were drilled in two phases to fully evaluate the soft clays that we found in the subsurface.
|
|
Fault Study, Eagle County, Colorado
Image of Dillon Reservoir
The Denver Water Department engaged MWW&AI to evaluate possible late Quaternary faulting in the area of the proposed Colorado River Tunnel in Eagle County. It was imperitive to deterime if faulting of any age was present at project sites, as it would affect the tunnel design. The presence of late Quaternary faulting would also indicate a seismogenic potential which could require assignment of a local earthquake, estimation of resultant ground motions, and the assessment of secondary seismotectonic hazards.
A possible splay of the Bond fault was seen as a potentially significant structure. Accordingly, DWD wanted an exploratatory trench excavated across the fault. This method would reveal the relationship of bedrock faulting to overlying Quaternary surficial deposits and would also be used to evaluate the ages of fault movement, recurrence intervals, net tectonic displacements, slip rates, and secondary deformational features. The ages of fault movement were constrained by relative and chronologic dating techniques
MWW&AI created a safe and economical man-made exposure for the evaluation of the presence/absence of faulting and fault history. We described the stratigraphy and structure of the trench exposure using state-of-the-art logging techniques.
|
|
Click image for close-up
)
)
)
)