The Harvell Dam in Petersburg, Virginia needed to be breached to reopen over 120 miles of the Appomattox River for expansion of spawning and rearing habitat to assist anadromous fish population restoration.
To support this effort, Froehling & Robertson, Inc. performed hydrologic modeling of the river system and flow through the dam, evaluating several breaching options. This analysis suggested that complete removal of the dam might be required to reach target flow velocities appropriate for fish passage under normal to low flow conditions.
F&R also provided sonar mapping of the upstream impoundment bottom, assessing sediment depths. Sediment samples were obtained and analyzed for contaminants while concurrently analyzing potential sediment transport. It was determined that removal of the dam would have no significant impact on downstream flooding or sediment deposition.
Furthermore, in an effort to better demonstrate to governmental decisionmakers and the general public what the impact of breaching the dam would be, F&R also created displays that showed before and “after” photos (created in Photoshop) of the dam.
When it came time to remove the dam, F&R completed permitting assistance and development of contractor bid documents, plans, and specifications for the actual breaching as well as served as construction administrator during the removal of the structure.