Merit Engineering has conducted an extensive geotechnical engineering investigation for the construction of three (3) apartment buildings, and associated parking, near downtown Bellingham. The location of the project site demanded a thorough subsurface investigation as well as supplemental investigations including a geophysical survey, extensive literature search on previous coal mine workings in the vicinity, and a bedrock integrity study. The site is located on a partially sloping property with exposed bedrock and a steep slope. Obtaining accurate subsurface conditions in order to provide feasible foundation options and recommendations was the main focus of the study.
The methods used to accurately define the subsurface conditions included hollow-stem auger test borings to 30′ below surface, excavated test pits, ground penetrating radar (GPR) survey, and an extensive literature search and review of existing documents on coal mines in the vicinity. Soil and groundwater conditions were logged and soil samples recovered for additional laboratory analysis in our in-house laboratory. The GPR survey results were carefully analyzed for subsurface anomalies, such as areas of disturbed sediments or subsurface voids that would help identify possible areas of abandoned coal mine workings. Using the acquired data from these methods, we were able to provide an accurate subsurface profile of the site and thus recommend a site-specific foundation system. Ultimately, our thorough investigation determined that the condos could be constructed on both a traditional footings foundation and drilled pilings into the unweathered bedrock below the site.
Merit Engineering has maintained rigorous commitment to this project during the construction phase by providing earthwork observation and inspection and ongoing technical support throughout the construction period. We also designed a 30′ tall geogrid reinforced slope for steeply sloping portion of the property.