College Lake Dam Stabilization/Removal Studies

Lynchburg, Virginia
Owner: City of Lynchburg

College Lake Dam was compromised when heavy rains pushed the large lake past capacity in early August 2018. WSSI coordinated with City staff to assess damages, focused mainly on the prioritized efforts at the dam. Within 24 hours of the request for assistance, we mobilized high-level engineering and construction management staff for on-site meetings and consultation.

WSSI, working with a team of City staff, regulators, and other consultants, performed site inspections and provided guidance on how to manage the extensive volume of lake sediments during the lake dewatering, which was necessary for inspection and repair.

Quantifying the sediment accumulation behind the earthen dam was critical for determining the best path forward, but traditional methods couldn’t be used – the site was too dangerous even when the lake bed was drained. WSSI deployed a UAV to collect the dry lake bed topography data. After multiple photogrammetry missions, WSSI developed a survey-grade 3D model of the existing conditions and extracted the detailed data for 3D design.

WSSI also made seed mix recommendations and coordinated aerial seeding of the lakebed to help temporarily stabilize the sediment.

Wetland Studies and Solutions, Inc. (WSSI) worked as a sub-consultant on a study for the College Lake Dam stabilization/removal project and served as the environmental lead. The dam had been identified as “high-hazard” and the team was tasked with evaluating the viability of reinforcing the structure or replacing the dam with a bridge. The project was complicated, as College Lake is located on privately-held property and the dam serves as the road embankment for a major Lynchburg thoroughfare.

WSSI’s primary responsibility was the evaluation and design of alternatives for restoration of the lake bed in the event that the dam is removed. Regulatory staff worked closely with state and federal regulators to assess impacts to Waters of the U.S. impacts, develop Clean Water Act permit conditions, and evaluate the project in the context of local TMDL and MS4 permits. WSSI staff developed a natural channel design framework based on the hydrology for the current and future watershed conditions of the 22 square-mile drainage area. In addition, our engineers and landscape architects worked to bring potential design alternatives to life through renderings of both the design alternatives. These renderings were critical in conveying design details and information to interested stakeholders at public meetings.

WSSI engineers analyzed sediment transport dynamics, which included assessing past, present, and future deposition rates; options for dredging operations to allow continued functionality of the lake (now 1/3rd of its original volume); and detailing the implications of dam removal on surrounding infrastructure and ecology.

_{Note that WSSI's work on the stabilization/removal concept was completed prior to the high-intensity, high volume rainfall of early August 2018.}