City of Sacramento
2009 – 2015
The 240-acre Sacramento Railyards site redevelopment made history as one of the largest urban infill projects in the nation. Blackburn Consulting completed geotechnical and foundation reports for four bridge structures (two UPRR grade separation structures) and new roads critical to initial redevelopment. Blackburn worked with the project team during a highly compressed design and construction schedule to solve challenges including a simultaneous UPRR track relocation project, significant funding issues, and several geotechnical challenges.
Key geotechnical issues included:
- deep compressible and liquefiable soil deposits, and the resulting large static/seismic pile downdrag loads,
- inconsistent upper gravel/sand bearing stratum with potential pile punching/hard pile driving issues,
- difficult subsurface exploration conditions (environmental cleanup site with specialized drilling protocol), and
- the need to protect historic buildings from construction vibrations.
Blackburn’s engineers mitigated the challenges through a pile test program during design, use of surcharge loads to mitigate static downdrag, recommendations for light-weight cellular concrete for mechanically stabilized earth (MSE) wall backfill, and recommendations for a pile-setup factor for use during bridge construction to confirm high pile load demands.
Blackburn provided quality assurance materials testing and special inspection services for many project elements during construction. Extending from H Street to Railyards Boulevard, the 5th and 6th Street projects include new bridges, viaduct structures, and associated MSE and cantilever retaining walls. Blackburn performed quality assurance testing of soils during over excavation and construction of bridge embankment fills, and sampled and tested light-weight cellular concrete during construction of MSE walls. We also performed compaction testing of sidewalk, curb/gutter, and roadway subgrade and aggregate base, sampling and testing of structural concrete, and acceptance testing of construction materials.
For the 7th, F, and G Street Extensions, Blackburn performed compaction testing of underground utilities, sidewalk, curb/gutter, and roadway subgrade and aggregate base. We also provided source inspection and special inspection of reinforcing steel for cantilevered cast-in-place retaining walls.
Winner of CalGeo’s 2011 Outstanding Project Award