Gwinnett County's goal is to continually improve the reliability of the wastewater system that thousands of its residents depend upon every day. The County's Master Water and Wastewater Plan (updated in November 2003), created with input from citizen groups and technical experts, recommended taking proactive steps to remove from service older, smaller treatment plants to improve reliability and be more cost-effective. This allows the County to implement newer technology, while still meeting stricter state and federal regulations. In south Gwinnett, the Department of Water Resources (DWR) undertook a series of projects from 2003 - 2007 to upgrade the system. Among them were a new pump station at the No Business Creek Water Reclamation Facility (WRF) site, the decommissioning and demolition of the NBC WRF, the installation of a force main (pressurized sewer pipe) along Springdale Road connecting the NBC pump station to an existing force main, and some modifications to the Jacks Creek WRF. The final piece of these improvements is the No Business Creek tunnel. The NBC tunnel will allow for the decommissioning of the Jacks Creek WRF as well.

What is the tunnel project?

The tunnel will be approximately 12 feet in diameter, ranging from nearly 200 feet to 80 feet deep, with a depth generally exceeding 100 feet. The length will be approximately 16,000 feet, about three miles, and the work will be performed primarily in deep, solid rock under Springdale Road and Everson Road. Entrance shafts will be constructed at the No Business Creek pump station site and the Jacks Creek WRF site. Two intermediate shafts will also be built along the route. One will be behind the CVS near the intersection of Springdale Road and Centerville Highway; the other one will be on Everson Road.

How much will the tunnel cost?

The cost for the tunnel is approximately $54 million. The majority of this cost, $42 million, will be offset with a State Revolving Fund loan from the Georgia Environmental Facilities Authority (GEFA) that was awarded to DWR in 2005. The remainder is already allocated in the Department's existing Capital Improvements Plan, so it will not affect current rates.

What are the advantages of the tunnel?

Tunnels have a long, technologically successful history. They minimize impacts to residents and businesses, offer a cost-effective, environmentally optimal solution, and provide the most reliable long-term system (life expectancy of the tunnel can exceed 100 years). The NBC tunnel will manage the wastewater flows from the No Business Creek and Jacks Creek drainage basins. It offers the added advantage of providing storage and equalization during peak flows, preventing sewage overflows. Some of the other advantages of tunnels compared to traditional wastewater pipelines include: preservation of community aesthetics, limitation of traffic disruptions for maintenance, reduction in maintenance and power costs associated with pumping stations and treatment plants, and environmental considerations, such as, minimal surface clearing and no stream crossings.

What does the term "equalization" mean?

Equalization simply means that during peak usage or storms, this part of the system will not become overloaded. Flows are not uniform throughout the day. In addition, during heavy rainfall, flows increase significantly. Instead of designing pump stations for the peak flows, it is much more efficient and cost-effective to provide equalization storage in the system that will shave the peaks off maximum flows and allow for smaller pumps. This will also help prevent spills and overflow situations.

Have tunnels been used elsewhere in Gwinnett County?

Gwinnett County has successfully used tunnels for years, including the Upper Chattahoochee Interceptor and the North Fork of Peachtree Creek located near I-85 and Pleasantdale Road.

How was the proposed route for the tunnel determined?

By combining engineering analysis with public input, the Department of Water Resources (DWR) chose the most feasible route. Several meetings on the project have been held since 2002 and the final design was developed based on comments and suggestions from residents who attended those meetings; subsequently the number of parcels with subsurface easements has been reduced from approximately 48 to approximately 40. This allows the tunnel to follow a route that affects the least number of properties and offers the most effective use of existing rights-of-way. Additionally, geotechnical work along the tunnel route shows that good quality rock does exist.

What is the schedule for the tunnel construction?

Contractors will begin setting up on the site in June with actual construction beginning later in the summer and lasting until approximately early 2010. Different phases are involved in the process, including shaft construction, boring, and construction of a pumping facility deep inside the mining shaft. Blasting will be involved during the excavation of the shafts. (For more information on blasting, please view the FAQs.)

What is the actual process of tunneling?

The tunnel will begin with an entrance shaft at the No Business Creek pump station site. The entrance shaft will be drilled vertically, with some controlled blasting required, until the tunnel elevation is reached. Next, a tunnel-boring machine (TBM) will be installed. The boring machine will drill the tunnel through solid rock until it reaches the exit shaft at the site of the Jacks Creek WRF. At this point, the tunnel-boring machine will be removed.

How long will the boring machine be in operation?

The boring machine will operate 24 hours a day and will average between 20 - 50 feet a day for approximately 24 months. All of this work will take place deep underground and people shouldn't notice when it goes by.

What will be done with the material excavated during tunnel construction?

The rock fragments and other material pulled out of the tunnel are marketable materials. The contractor will be responsible for handling this material. It will be temporarily stored on site at the No Business Creek pump station then hauled to the appropriate facilities in an approved manner for reprocessing and ultimately beneficial use. Trucks will remove the material on a daily basis. The work hours for material removal are limited from 9:00 a.m. to 4:30 p.m. so as not to conflict with school bus schedules or commute times.

Will my property be damaged by this construction?

It is highly unlikely. One of the advantages of tunnel construction is that it is considered much less likely to cause an impact than conventional buried sewer line construction since it involves a completely isolated boring technique deep below the surface of the earth in solid rock. Because boring offers the latest technology and the machine can travel nearly 50 feet per day, the time it is directly below an individual's property will be very short.

Will my property value be adversely impacted?

This has not happened with other tunnel projects in the metro Atlanta area or in other parts of the country. For example, when new homes were built along the route of the Chattahoochee tunnel in Cobb County, which was completed in 2004, they sold in the exact same range as other homes in the subdivision.

Could storing wastewater flows in a tunnel affect the groundwater?

No. The tunnel will be deeper than the groundwater table. Gravity prevents the wastewater from "flowing up" into the groundwater. Since the groundwater is also controlled by gravity and will try to flow toward the lowest spot, DWR will take steps to prevent the groundwater from entering the tunnel. While DWR's investigations have found the rock to be generally sound, during the tunnel boring operation the exposed rock surface will be inspected and sealed where necessary.

Will there be odor?

Air within the tunnel will be channeled through an odor control building to capture any odors that might develop.

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How is safety being addressed in the area of the shafts?

The entrance and exit shafts are being constructed on county owned property. The area where the shafts are being constructed will be fenced and secured to prevent entry. The shaft is designed with multiple levels of safety to prevent entry, including locked chambers, heavy safety cages, locked heavy metal doors, and bolted lids.

Will my plants such as trees or shrubs planted above the tunnel die?

Because the tunnel is so deep in solid rock, with depths averaging 100 feet, trees and landscaping directly above the tunnel will not be affected. Vegetation usually extends its roots within the soil above the solid rock and rarely deep into solid rock.

Is there a risk of sinkholes at some point?

The tunnel will be constructed in granite and gneiss, rock types that do not form sinkholes. These rock types are not like limestone found in Florida or Louisiana, which are prone to sinkhole development in a wet environment.