Eric Byrne, Water Resources Engineer, Tetra Tech
Charles Crowell, Stormwater Section Manager - Engineering and Construction, Gwinnett County Department of Water Resources
Tetra Tech engineers provided construction support services to the Gwinnett County Department of Water Resources during construction of a project involving two bioretention basins and a stormwater wetland. Successful implementation of these types of Green Infrastructure projects largely depends on a continuously evolving list of best practices regarding construction methods and field inspections. Allowing design engineers to participate in construction proved to be beneficial for all parties, from standard construction administration and the coordination of field changes to valuable lessons learned that may inform future Green Infrastructure design and implementation best practices. During construction of the Garner Creek Demonstration BMP project, Tetra Tech engineers were tasked with performing typical construction administration services, including review of RFIs, submittals, and pay applications. Tetra Tech engineers also conducted site inspections on a regular basis to report on construction progress and ensure adherence to best practices regarding Green Infrastructure construction. These inspections resulted in increased communication and contact time with the design engineer, which provided greater opportunity to share knowledge, identify potential issues, and helped expedite design changes to accommodate conditions in the field. For example, observations shared in the field regarding forebay configuration and the placement of engineered soil media in infiltration practices led to field changes and design considerations that will be carried forward into future GI projects. The likelihood of successfully constructing any type of engineered project improves when the design engineer is involved in the construction process. This notion may be especially applicable to GI projects given the relatively recent growth of GI and low impact development – which can be plagued with faulty design assumptions and costly repairs or reconstruction due to contractors’ inexperience with GI concepts. The Garner Creek Demonstration BMP project is an example of successful GI project implementation through increased collaboration with design engineers during construction.