I-95 Widening MM 0 to MM 8

The South Carolina Department of Transportation (SCDOT) is developing construction plans for improvement to I-95 from the Georgia state line (MM 0) to the US 278 interchange (MM 08). The improvements principally including widening the interstate from two lanes in each direction to three lanes in each direction. The improvements will include replacement of four pairs of bridges along the I-95 mainline that cross the Savannah River, an overflow channel of the Savannah River, Sand Island Swamp, and the Seaboard Coast Line (SCL) Railroad; replacement of the John Smith Road bridge over I-95 near MM 6.9; and reconfiguring the Exit 8 interchange which will require replacement of the US 278 bridge over I-95. A new interchange at the existing Purrysburg Road overpass is also part of the improvements (MM 3).

As part of the KCI team, S&ME performed geotechnical explorations along the entire project corridor to characterize the subsurface for the bridges and roadways. The field exploration consisted of soil test borings (STB), cone penetration test (CPT) soundings, seismic cone penetration test (SCPT) soundings, dilatometer test (DMT) soundings, bulk soil (BS) sample collection, and Multi-Channel Analysis of Surface Waves (MASW) testing. Over-land, barge-mounted, and amphibious drilling platforms were utilized to complete the exploration. Multiple SCDOT certified Disadvantage Business Enterprises (DBE) were utilized in our field exploration program.

S&ME also performed a site-specific response analysis to evaluate the seismic hazard and the risk of soil liquefaction and impact on the proposed bridges was determined.  Liquefaction mitigation design was accomplished using methods adopted from Caltrans (California DOT) and ground improvement where needed.

S&ME also performed a Phase I Environmental Site Assessment (ESA) in compliance with American Society for Testing and Materials (ASTM) standard E1527-13 Standard Practice for Environmental Assessments: Phase I Environmental Assessment Process. The ESA was conducted along the existing project corridor. Phase 2 soil and groundwater sampling was conducted for several recognized environmental conditions. S&ME is also completed hazardous materials (asbestos and lead based paint) surveys of existing bridges so that demolition materials are properly characterized, handled, disposed, and recycled for both worker protection and environmental protection.

Although SCDOT retained the pavement design responsibilities for the new proposed travel lanes, S&ME performed an evaluation of the existing pavements, collected additional cores and subgrade information (FWD testing), and has also designed temporary pavements for maintenance of traffic.