Challenge

Our client planned to develop a 9-acre former lumber yard into a multiple structure development, referred to as the Mill District, which included a public hotel, three residential condominium buildings (one slated as low-income housing), amenity support building, and public infrastructure improvements that would surround the entire property. Our client required geotechnical engineering services through several phases of development. The Mill District property is located within a zone of high liquefaction potential during strong earthquake ground motion.

Solutions

The client hired Geo-Logic Associates wholly owned subsidiary, RGH Consultants (RGH) to provide geotechnical engineering services for a multiple structure development with public infrastructure improvements. RGH performed several comprehensive geotechnical studies to provide recommendations for various phases of development including site preparation and grading; engineering analysis of settlement and liquefaction potential; and geotechnical design for foundations, retaining walls, and concrete slabs on grade, utility-trench excavation dewatering and backfill, and geotechnical engineering drainage improvements. Our studies utilized the drilling and sampling of soil borings and pushing of cone penetrometer tests (CPT) to evaluate subsurface soil and groundwater conditions, and liquefaction analysis using CLiq – CPT Liquefaction Assessment Software.

As part of a design team, RGH continued to provide geotechnical consultation through multiple phases of design and construction improvements. Our geotechnical recommendations for the Mill District development included a public frontage roadway and utility improvements, a four-story low-income housing condominium building, a four-story high-end condominium building with underground parking, and an amenities and support-services building, as well as a four-story public hotel. Working closely with design team members and the local municipality, the public infrastructure improvements, including roadways, sidewalks, sanitary sewer, storm drain, water, and joint trench utility installation were designed and constructed in accordance with current building code standards. RGH provided field observation and materials testing services and special inspection services during construction to ensure work was performed in accordance with our geotechnical recommendations and building design criteria and standards.

Results

RGH provided geotechnical engineering consultation, field observation, and materials testing and special inspection services through the various phases of design and construction of the Mill District project. Our creative and effective geotechnical recommendations, and subsequent geotechnical observation and testing throughout construction, have provided the client with cost-efficient solutions to the liquefaction potential of the area, while adhering to development goals over the entire property.