San Diego Chargers Training Facility
San Diego, California
Scope of Work:
- Geotechnical Evaluation
- Geotechnical Observation and Materials Testing
- Close Coordination with Agency
- Geotechnical Engineering Analyses
- Written Report
Ninyo & Moore performed geotechnical consulting services during the design and construction phases for the Emergency Storm Drain Pipe Replacement project at the San Diego Chargers Practice Facility. During a rain event, a sinkhole developed around a storm drain vault located at the western side of the practice facility. After further evaluation, the existing 54-inch diameter reinforced concrete pipe (RCP) was found to possess several voids within the pipe. To repair the damage, portions of the existing storm drain pipe were lined with HDPE casing and other portions were removed and replaced with a new storm drain system. The new system included a 7 foot by 4 foot reinforced concrete box, a drainage inlet with head walls, a low-flow bypass, a drop structure, and an energy dissipating structure. As part of the repair, portions of two existing segmental retaining walls were reconstructed.
Project Challenge: The construction of a portion of the new storm drain alignment passed in front of an existing geogrid reinforced segmental retaining wall. At one location, the alignment passed only a few feet in front of the retaining wall with the potential for undermining the wall. Furthermore, the existing wall was used as a stabilizing mechanism for a slope with instability concerns.
Innovative Solution: Supplemental geotechnical borings were performed at the base of the retaining wall to sample and test the existing foundation soils. The information obtained was used to further evaluate the wall stability and to optimize the temporary excavation for the storm drain.
Services: During the design phase of the project, Ninyo & Moore performed a subsurface exploration which included the drilling of exploratory borings along the proposed and existing storm drain alignments as well as behind the existing retaining walls. Laboratory testing was performed on the encountered soils and a geotechnical report was prepared providing our recommendations for the geotechnical aspects of the project relating to earthwork design and construction such as soil corrosivity, soil compaction, soil shear strength, and slope stability.
During the construction phase of the project, Ninyo & Moore provided geotechnical observation and materials testing services. The geotechnical observation services included field density testing during storm drain trench and retaining wall backfill, site evaluation of temporary slopes and trench excavations, and laboratory testing of soils used by the contractor. Materials testing for the project included conformance testing of reinforcing steel and compressive strength testing of concrete.