Client
City of Bristol
Department of Public Works

Location
Bristol, Virginia

Performance Period
1990-Present

Services
Design engineer including geotechnical, civil, hydraulic, and environmental engineering analysis and preparation of plans and specifications
Groundwater Consulting including modeling, monitoring, analysis, and reporting
Construction Field Services, including QA/QC, Contract Administration, and documentation
Operations Engineering, including equipment selection, operations safety, operations plans

Project Scope
STS was hired by the City of Bristol to convert a former limestone rock quarry into an 8,000,000 CY municipal waste landfill having a 6 acre base footprint. The quarry is 300 to 350 feet deep and has lateral dimensions of 600 feet by 2,000 feet.

Since 1990, STS engineers have successfully taken the project from concept through a dual permit approval process with the Virginia Department of Environmental Quality, design, construction, and Phase I operations start-up.

The development of the quarry presents several unique challenges. The first of these is stabilization of the steep sidewalls to limit and contain rock falls. This is being accomplished via a combination of rock bolting, rock scaling, draped mesh and wire rope net, and placement of rock fall protection fence along the existing haul road. The stability of the rock walls was evaluated utilizing detailed geologic mapping of the rock faces in combination with stability analyses, rock coring and laboratory testing.

The second challenge is the seepage design of the liner system for the sidewalls. While the liner design for the quarry base is a relatively conventional composite clay/geomembrane liner, the approved sidewall liner incorporates the draped wire mesh along with a protective layer of geotextile, PE geomembrane, and a geocomposite drainage layer. A buffer zone is used between the waste and the liner system to protect the liner. The liner design included material investigations to determine borrow sources for the clay liner.

A third challenge is handling of groundwater infiltration. The design incorporates a drainage control layer, which captures seepage and conveys it to a discharge location. Seepage analyses indicated that this will maintain the existing inward gradient, which effectively makes the discharge location the down-gradient monitoring location for the landfill.

The project design also included the design of 9 to 14 foot diameter tunnels and raised bore shafts to accommodate leachate and storm water facilities. A 0.5 MGD leachate storage tank was also included for storage of leachate during peak storm events.

STS subcontracted the design, permitting, and design oversight of the 800 TPD baling facility/transfer station, which is part of the Phase I initial startup development. Mattern and Craig, from Roanoke, Virginia performed the engineering on this portion of the project.

Construction on Phase I of the project was completed in early 1998. Landfill Operations were transferred from the existing facility to the new facility on March 2. STS is providing operations and construction consulting services for the new facility.

Unique Issues

• Unique physical setting presenting challenges from an engineering, construction, and operations standpoint.
  
• STS has worked closely with the Owner, contractors, State regulatory personnel, and subcontractors to develop an innovative approach that has proven to be successful in a very unique setting.
• The Owner is extremely pleased with the operation to date and is anticipating future expansions in the short term.
  

Client Benefits

• STS's expertise has allowed the Owner to complete a challenging project that had many potential pitfalls associated with it.
  
• Our field personnel helped keep the project on schedule during the Summer of 1997 to allow the City to continue to solicit new waste contracts while construction was underway.
  
• The City of Bristol is now operating a unique, long-term landfill that is viable economically for themselves and the surrounding communities.
  

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