The Alexandria Old Town Project is located in Alexandria, Virginia. For many years it was a bus depot used for repairing and maintaining city busses. Trammel Crow Residential is currently developing the property into a multi-family apartment facility. Knowing that the new construction excavation would reach below the existing groundwater table, Trammel Crow teamed with Griffin Dewatering to develop implement a comprehensive groundwater control plan.
While there was limited water quality data, after considering the history of the site Griffin anticipated there to be some groundwater contamination. Having significant experience in this area of Alexandria, Griffin was also aware of the potential for high, naturally occurring iron in the groundwater. The Griffin team developed a preliminary design and estimate based on the limited information at hand.
Griffin then worked with Trammel Crow to develop a test procedure that would provide data needed to refine our dewatering and treatment design. Facing the challenge of a tight schedule, Griffin was able to mobilize to the site to install a test well and three piezometers. This allowed us to perform pump tests and collect important drawdown data. Simultaneously, we pulled and tested raw water quality samples that verified the presence of contaminants as well as excessively high levels of naturally occurring iron in the groundwater. Thanks to Griffin’s quick work, we were able to gather this much needed information and redesign our systems without delaying the construction schedule.
While the existing structures were being removed, Griffin worked with Trammel Crow to develop the best value dewatering and treatment plan that incorporated construction groundwater control with the safe removal of groundwater contaminants.
Once the systems were installed, Griffin helped to manage costs by monitoring the dewatering wells and the treatment system simultaneously. We were able to adjust the dewatering flow to a minimize treatment costs while maintaining a safe, workable site. Another cost saving feature was the optimized discharge design in our treatment system. This allowed the clean treated water to be discharged in the storm sewer while discharging a minimum amount of water into the sanitary sewer. This maximized the treatment efficiency while limiting costs associated with hauling and disposing contaminants.
Griffin was able to successfully design, install, monitor, and remove the full system while allowing Trammel Crow to stay on schedule. Griffin was faced with a tight schedule, limited geotechnical and water quality information, and a high level of contaminants. We overcame these challenges by using our vast experience, the knowledge of treatment and design teams, and our very capable operations crew. It is because of the above obstacles, and how Griffin successfully navigated them, that we believe this project deserves to be awarded the Metropolitan Washington Excellence in Construction award.