University Lake Dam Improvements

Client: Orange Water and Sewer Authority (OWASA)
Location: Carrboro, NC

Hazen and Sawyer has provided engineering services to the Orange Water and Sewer Authority (OWASA) for over 25 years in connection with University Lake, one of two surface water supplies serving the towns of Chapel Hill and Carrboro and southern Orange County. Constructed in the 1930’s by the University of North Carolina at Chapel Hill, OWASA leases the lake from the university. In addition to raw water storage, the lake is an important recreational facility for the community.

University Lake showing recreation facilities for UNC Chapel Hill.

Concrete non-overflow section viewed from abutment with earthen embankment dam.

Ogee spillway crest with timber flashboards viewed from concrete non-overflow section.

Earthen embankment dam viewed from abutment with concrete non-overflow section.

Tie-down Anchor Detail.

Inundation mapping performed for the University Lake Dam Emergency Action Plan (EAP) showing inundation extents immediately downstream.

Inundation mapping performed for the University Lake Dam Emergency Action Plan (EAP) showing inundation extents including major roadways downstream.

Inundation mapping performed for the University Lake Dam Emergency Action Plan (EAP) showing inundation extents including major facilities downstream.

Project Outcomes and Benefits

  • The dam and spillway meet North Carolina dam safety standards.
  • Spillway flashboard replacement increases storage capacity and is consistent with dam safety standards.
  • Preparation of Emergency Action Plan (EAP) for coordinated tabletop exercise attended by local and state emergency management officials.
  • Regular inspections of University Lake Dam and related inspection reports.
  • Evaluation of potential increase in dam height and storage capacity.
  • Design of computer model to assist OWASA in optimizing reservoir storage utilization and yield.

Major assignments include a Phase II Dam Safety Study under the National Dam Safety Program, followed by the design and construction phase services for improvements to increase dam stability and spillway capacity to meet state dam safety standards. Structural improvements included installation of multistrand steel tie-down rock anchors in the concrete overflow and non-overflow sections, and raising the non-overflow section and the earthen saddle dam by 7 feet.

For more information on this project, or to discuss a similar project in your area, contact Jeffery Powers at jpowers@hazenandsawyer.com