WESTVACO PLANT SITE
An Engineering Excellence Award-Winning Project

Westvaco Corporation asked S&ME for a geotechnical second opinion of an earlier site evaluation effort at its Charleston, South Carolina area facility. We were to review the original foundation and retaining wall designs for various facility structures under consideration, perform additional field and laboratory testing, and evaluate the subsurface conditions to provide recommendations for more cost-effective solutions.

Our specific earthwork recommendations to improve the soils beneath the slope were aimed at gaining a more cost-effective retaining wall design. Our supplemental exploration applied a fairly new and innovative soil-testing device. In addition to traditional soil-test borings, S&ME performed dilatometer testing, which involves inserting a specially designed instrumental blade into the soil and measuring the lateral pressure required to push a membrane into the surrounding soil.

After evaluating subsurface data, our engineers recommended that a combination of ground modifications be implemented to improve the soils before construction, thereby reducing post-construction settlement to a tolerable amount and allowing conventional shallow foundation support. S&ME has recommended these soil improvement techniques for many projects in the Charleston area, and in all cases, these methods have met the project requirements and proven to be more cost effective than deep foundations.

S&ME faced considerable challenges in addressing site conditions and providing Westvaco a solution to its initial costly design recommendations from an earlier consultant. Among the techniques used were surcharging and vibroreplacement (i.e., the installation of stone columns using viabratory methods). Vibroreplacement densifies and reinforces the soil to allow shallow foundation support of much heavier structural loads than possible with an unmodified subsurface strata. The ground modification techniques recommended provide an excellent case history that can be applied to projects at numerous sites where coastal soils need improvements.

By limiting site settlement, our design for the containment aprons will help serve Westvaco's objective of containing any chemical spill should one occur. Also, the freshwater basin will remain in its natural state throughout the construction and life of any the new development being considered.