Challenge

Calistoga Hills Resort is a privately owned, approximately 120-acre property planned for development into a large-scale, wine country destination, hillside resort, and residential project. Our client required geotechnical engineering services to evaluate subsurface soil, bedrock, and groundwater conditions, and provide design recommendations for grading, creek crossings, hillside building foundation stabilization, and access roadways, pathways, and underground and aboveground utility improvements.

Solutions

The client contracted with Geo-Logic Associates wholly owned subsidiary, RGH Consultants (RGH), to provide geotechnical engineering services over many years and phases of project design and construction of the Calistoga Hills Resort. We initially performed geotechnical studies for a fire-access road, utility bridge, water storage tanks, and a filling pump station. These studies included recommendations for grading, drilled piers, and soil nail wall construction along the access roadway. RGH performed additional geotechnical studies over the years as the client expanded the resort design to include guestroom buildings; luxury spa treatment areas; a signature restaurant, bar, and pool areas; valet and luggage storage building; and an event and meeting space referred to respectively as the Spa Building and Long Barn areas.

Each study provided updates to our previous geotechnical design recommendations in accordance with current building code standards. RGH provided additional report updates for retaining wall recommendations to include compliance with current seismic design requirements, prepared recommendations for overall geotechnical site drainage. RGH performed and completed additional exploration, sampling, and analysis for hillside vineyard improvements and a new equipment barn building, also known as the Back of House (BOH) or DeGuarda Service Center for the resort, which included a parking lot, facilities maintenance building with loading docks, two large-scale aboveground water storage tanks, back-up generator systems, and connection to the fire-access road from Foothill Boulevard to Madrone.

As the resort development plan expanded over the years, RGH provided continued communication and consultation for geotechnical recommendations, from soil nail wall design for the uphill side of the new parking lot, swimming pool and jacuzzi excavation and drainage criteria, and soldier beam and lagging wall support for the connecting roadway. We provided updates for our geotechnical recommendations throughout construction of the Calistoga Hills Resort project. At the same time, we provided geotechnical field observation and materials testing and special inspection services throughout each phase of the resort development expansion and construction.

Results

RGH has provided geotechnical engineering and design services, field observation and materials testing, and special inspection services during the approximate ten-year construction of the Calistoga Hills Resort project. Our geotechnical services have supported our client’s development goals with quick response times, ongoing geotechnical report updates and clarifications to ensure compliance with the most current building code requirements, and creative solutions to conceptual resort design improvements through the life of this project.