Lake Harbour Drive Extension

Ridgeland, Mississippi

Burns Cooley Dennis, Inc. (BCD) performed the centerline soil profile and provided geotechnical engineering services for the design of a new bridge over I-55 for the Lake Harbour Drive Extension in Ridgeland, Mississippi. The bridge over I-55 has a total length of about 415 ft and consists of four pre-stressed concrete beam spans. The approach embankments have a maximum height of about 27 ft. Pile-supported cantilever retaining walls were required along the flanks of the east and west approach embankments.

Subsurface soil conditions along the alignment of the bridge and retaining walls were explored by means of six borings. Laboratory testing was performed to investigate the classifications, volume change characteristics and shear strengths of the soils encountered in the bridge and retaining wall borings. Recommendations were developed for H-pile, prestressed concrete pile, and drilled shaft foundations. Analyses were performed to evaluate the settlement and stability of approach embankments. The seismic site classification and site variability were established based on LRFD criteria, and appropriate resistance factor and load test recommendations were provided.

For the centerline profile, twenty-two (22) soil borings totaling 160 ft in depth were drilled for this project. The borings were taken along the centerline alignment of the proposed Lake Harbour Drive Extension. The soil borings were generally spaced at 100 ft to 200 ft intervals with spacing at 100 ft in cut sections and 200 ft in fill sections. The soil borings were made to varying completion depths below the existing ground surface based upon the anticipated amounts of cut or fill. In cut sections, the borings were made to a minimum depth of approximately 5 ft below the proposed centerline finish grade, and in fill sections, the borings were made to a minimum depth of approximately 5 ft below natural ground.

Laboratory testing of the sampled soils was conducted to classify and evaluate the expansive properties of the various soils encountered. Testing consisted of sieve analyses, hydrometer analyses, Atterberg limits and volume change with shrinkage limits. This series of tests was conducted on twenty-two (22) samples considered to be representative of the various soil types encountered along the alignment. In addition, testing for pH, resistivity and sulfates was conducted on seven (7) samples that were considered representative of the in-situ soils.

Along the entire alignment of the Lake Harbour Drive Extension, BCD tabulated areas in which high volume change soils, muck, and undesirable soils were encountered. A centerline profile was provided that documents the strata of soils encountered.

Burns Cooley Dennis, Inc. performed dynamic pile testing (PDA) of test/production prestressed concrete piles and provided recommendations for production pile tip elevations; and evaluation of the proposed driving system and driving criteria recommendations for production piles were based on the PDA and Wave Equation Analyses (WEAP).

Burns Cooley Dennis, Inc. interpreted and provided recommendations for production shaft tip elevations using the results of the bi-directional load testing performed by the contractor.