  
    Orange County requested assistance to upgrade the erosion control system for a 40-foot-high earthen dam, concrete control weir, and spillway structure to control the flow for a 150-acre surface water reservoir. The county wanted to develop a system to combat wave action and steep slope erosion along the 1,000-foot berm and near the concrete control weir to restore the slope of the earthen dam to its original configuration and mediate future erosion.
  

Alpha & Omega Group retained a subconsultant to provide a topographic survey of the impoundment side of the earthen dam (approximately 1,000 feet in length) from the top of the dam down to approximately 30 feet into the lake. Another subconsultant provided subsurface soil data via bores in the berm slope and in the in-situ soil to assist with the study.

Using the data, A&O produced a preliminary design report for the county summarizing potential options for repair. The selected design used articulating concrete block revetment mats and cast-in-place concrete walls. The team provided construction plans, technical specifications, and engineer’s opinion of probable construction costs. A&O's final design plans were forwarded to the county for submittal to NCDEQ Dam Safety and NCDEMR Land Quality for approval. Ω

Overview
Client: 
    
Orange County, NC
Location:
Hillsborough, NC
Subconsultants:

  CH Engineering – Topographic Survey

  Kleinfelder – Subsurface & Geotechnical Exploration
Contact:  
Christopher J. Sandt, PE

      Staff engineer 
 Orange County, NC

    919-245-2583
Professional fees:

    $50,120
  
Project Cost:
 $400,000 (est)
Start/completion date:  
8/2020 – Ongoing
Project manager:  
Bill Needham, PE

    Forrest Robbins

  Experience
  Coordination
Structural repair design
Construction plans
Technical specifications
Cost estimate