USPS Parking Garage
Services Applied by VCS Engineering
Project Description
The United States Postal Service (USPS) headquarters are located at L’Enfant Plaza in downtown Washington D.C. The headquarters building has a 6-level sub-grade parking facility directly below the building. The garage was constructed using cast-in-place conventionally reinforced concrete with an elastomeric coating wearing surface. The parking facility is being evaluated as part of an organizational-wide USPS facilities management and rehabilitation program. The parking facility is experiencing concrete deterioration in the form of spalling, delamination, cracking, and corrosion. The facilities management program is being led by Parsons, who subcontracted Vector Corrosion Services (VCS) to provide corrosion evaluation and rehabilitation expertise for the USPS L’Enfant Plaza parking facility.
Scope
VCS completed an on-site corrosion assessment of the USPS headquarters parking facility so that an effective rehabilitation could be designed.
The on-site assessments included:
- concrete delamination survey
- ground penetration radar (GPR) survey
- polarization testing
- cover-depth over reinforcing steel
- rebar size and spacing determination
- chloride profiling
- concrete resistivity
- carbonation depth analysis
Project Solution
VCS concluded that the elastomeric coating had failed on the upper levels and ramps of the garage due to vehicle wear, allowing for chlorides from deicing and moisture to reach the concrete. In addition, poor patching to the top of the slab provided additional pathways for moisture and chlorides. It was identified that levels A, B, and C had relatively greater damage and corrosion than other levels.
The amount of damage decreased as one moved deeper into the garage. This was due to the source of the chlorides being vehicle traffic, which was more on levels A, B, and C than on the lower floors. The chloride content at a steel depth throughout the garage was at levels that indicate active corrosion could initiate. Based on the condition assessment results, VCS provided various options to Parsons to extend the service life of the garage.
The client selected a targeted galvanic approach to be taken on levels A, B, C, and all ramps, while levels D, E, and F could be left as is. A targeted galvanic approach provided a cost-efficient solution to the USPS for a major service life extension of their garage.