After almost twenty (20) years of service, sections of a Mechanically Stabilized Earth (MSE) wall located near the main Terminal were jutting out of plane because of a buildup of hydrostatic pressure behind the wall.  In order to prevent infiltration that would contribute to further buildup, Sigma recommended the installation of a storm drain system and the installation of asphalt concrete pavement over the unpaved area behind the existing MSE wall.

While researching the cause of the water build-up behind the MSE wall, Sigma engineers also discovered that three nearby bridge superstructures were suffering from serviceability issues associated with the original system’s design.  Plastic drainage piping originally installed with the bridges had cracked and come apart inside the bridge decks, causing water to build up over time and seep through the concrete decking showing up as efflorescence on the soffit of the bridge deck.  Other problems included conditional degradation of prior repairs of deck joints, unrepaired concrete spalling that had exposed reinforcing steel, and surface cracking on the deck of the bridges.

Sigma prepared a Technical Memorandum describing each of the problems discovered in the initial research in detail, and the recommendations for repair of these problems. The Technical Memorandum included short term repair ideas and long term maintenance recommendations.

Upon Owner approval of the recommended short-term repairs, Sigma prepared plans, specifications, and cost estimates for the repairs of the north and south helix bridge that were included with the contract documents of the MSE Wall site modifications.  These plans included construction phasing requirements that assured that pedestrian and vehicular traffic remained uninterrupted.