GZA GeoEnvironmental, a geotechnical and environmental consulting firm, has received the 2012 Engineering Excellence Special Recognition Award from the American Council of Engineering Companies (ACEC) of Maine for their embankment preload program as part of the Veteran’s Memorial Bridge Replacement Project in Portland and South Portland, Maine.
The South Portland Approach for the Veteran’s Memorial Bridge Replacement faced difficult constraints, including waterfront construction over the mudflats, permit-based limits on the allowable disturbance area, and a subsurface profile including up to 90 feet of moderate-strength, compressible marine clay. The preliminary and final design and construction of a preload program for the South Portland Approach was executed by the design-build team to provide a cost-effective, safe solution that met the project performance and safety criteria. GZA was the engineer-of-record for the South Portland Preload portion of the project, responsible for design and construction documents and a member of the Reed & Reed / T.Y. Lin International design-build team.
GZA envisioned a 25-foot high earthfill preload embankment supported by temporary, anchored, sheet pile cofferdam to limit the environmental impact on the mudflats and developed this concept for preliminary design. During final design, GZA developed a subsurface model for geotechnical engineering evaluations and evaluated short-term and long-term global stability, long-term settlement adjacent to proposed piles, and general approach embankment areas and designed and installed wick drains to promote consolidation. The design met the constraints imposed by the Design-Build RFP, allowed for efficient foundation design, and was constructible for the contractor. The South Portland embankment concept saved over $1 million compared to alternative design approaches. The design incorporated Maine DOT, highway and bridge designer, and constructor collaboration through detailed design reviews at the 50 and 80 percent submittal stages.
Geotechnical instrumentation was designed, installed, and monitored to assess the performance of the preload, including settlement plates, piezometers, and inclinometers. The instrumentation confirmed that the preload goals had been achieved, and GZA recommended removal of the preload in winter of 2011, approximately five months ahead of schedule.
Founded in 1964, GZA GeoEnvironmental is a multi-disciplined firm providing environmental consulting, geotechnical and geo-civil engineering, environmental remediation, regulatory compliance, litigation support, air quality, solid waste services, specialty construction, occupational health and safety, and site development services. GZA maintains corporate offices in Norwood and has 550 employees and operates 24 offices in the Northeast, Mid-Atlantic, and Great Lakes regions. For additional information, visit www.gza.com.