Conoco-Phillips Refinery Rodeo

Conoco-Phillips proposed a 30% expansion of their San Francisco refinery located in Rodeo, California. The objective of the project was to produce cleaner fuels from current by-products, avoiding the necessity to import additional crude oil to the refinery. The proposed expansion would include facilities to process heavy gas oil, a hydrogen plant with a capacity of 120 million cubic feet per day, a hydrocracker with capacity of 23,000 barrels per day, a sulfur recovery unit of 200 tons per day, and a butane rail loading facility. The proposed $600 million additions would upgrade the refinery’s capacity to 1 million gallons per day.

Group Delta Consultants reviewed the existing geotechnical report and identified the potential for significant savings in grading and unsuitable soil disposal costs in the Sulfur Area where the existing geotechnical report recommended removal of 10 to 15 ft of existing fill. GDC took over as geotechnical engineer of record on the project and performed a design level geotechnical investigation and submitted reports for the Unicracker Facility Makeup Gas Compressor, REI Pad Area, Sulfur Area, Hydrogen Plant, Warehouse Area, Switchyard Area, Plant Access Road, and the MTC 23 Butane Loading Area. GDC also provided onsite geotechnical inspection during construction.

Key Achievement:
The use of surcharge in lieu of removal and disposal of more than 32,000 cubic yards of unsuitable soils saved the project up to 20 million dollars in disposal cost of the soils. The existing fill was consolidated in place by a surcharge of 7 ft. The surcharge was successfully completed within 60 days and the project units were successfully constructed.

LDK Polysilicon Plant,
Xinyu City, China

Based on a preliminary geotechnical investigation which indicated variable subsurface conditions, local Geotechnical Engineers recommended pile foundations for the support of for all heavy, important, and settlement sensitive structures.   The owner had proposed a very aggressive construction schedule. Time required for the construction of large number of piles made it very difficult to meet the schedule if deep foundations were selected for the support of the plant structures. 

Settlements of native soils and bedrock were measured during site grading when up to 15 m of fill was placed to achieve the finished site grade.  These measurements provided an accurate assessment of compressibility of the native soils and fills.  Full-scale test fills measuring 20 by 20 m (top dimensions) by 6 m high were placed at the finished grade to measure compressibility of both native soils and fill.  Where settlements were unacceptable such as areas with deep fills or soft soils, surcharge of up to 10 m was placed to reduce post-construction settlements.   Measurements of settlement were made during construction of major structures and tanks and actual settlements compared favorably with predicted settlements. 

• GDC provided geotechnical recommendations for the entire 1.6 billion dollar plant.

• Detailed geotechnical investigation included drilling 285 borings and performing 616 Cone Penetration Tests (CPTs)

• By eliminating pile foundations, GDC recommendations resulted in savings of over 50 million dollars in foundation costs and interest on investment due to reduction in construction time by 3 to 6 months.

• All work was performed to the latest international and Chinese GB Code standards.

Hamaca Crude Upgrader Project, Venezuela

Shortly after construction on the $1.2 Billion, 180,000 barrel/day capacity Hamaca crude upgrader refinery began, the site experienced heavy rainfall and tank foundations started to collapse. As the rain frequency and amount increased, sinkholes and collapse features appeared throughout the mile-square site. The design-build contractor contacted Group Delta Consultants to come to the site and determine the cause of the sinkholes and collapses. After we conducted a series of tests, we determined that the cause of the problem was collapsible soils. The original soil report and site preparation geotechnical consultant had concluded that collapsible soils were not present at the site. However, our tests showed the significant presence of these soils with moderate to severe damage potential if left unremediated. GDC reevaluated the site and suggested that the site be regraded at critical foundations that included removal of porous soils then recompacted. The client agreed and the site was re-graded and the refinery was handed over to the client before the deadline. As part of our services, we evaluated the following geotechnical aspects of the project:

• General geologic and subsurface features along the alignment, including interpreted lithology, and soil and groundwater conditions, and their impact on the proposed construction;
• Geologic hazards, including faults, seismicity, landslides, and liquefaction/settlement potential;
• Excavation considerations, such as in areas for critical structures, in non-critical structures and roads, the collapse of soil will be a maintain consideration which included removing collapsible soils than re-compacting to 95% relative soil density.;