| Project Location : |
Atlanta,
Georgia, USA
|
| Owner : |
Cobb
County Water System (CCWS)
|
| Design Firm : |
Jacobs
Associates, Inc.
|
| Contractor : |
Gilbert/Healy
|
| Construction Manager : |
Parsons
Engineering Science in conjunction with Jacobs Associates, Inc.
|
| Purpose of the Tunnel : |
To
provide sewerage conveyance for flows from eastern Cobb County, an area
that is currently being served by existing sewers that are near capacity.
|
| Total Tunnel Length : |
9.5-mile
|
| Excavated Diameter : |
18-ft
|
| Secondary Lining : |
1-ft
thick in-place concrete lining
|
| Excavation Start : |
June
2000
|
| Excavation End : |
Planned
for May 2004
|
| Bid Value : |
133,600,000
USD
|
| Geology : |
The
rocks in the area of the Chattahoochee Tunnel Project are mainly medium
grade metamorphic rocks with a small percentage of granitic rocks. Along
the tunnel alignment the metamorphic rocks include phyllonite, mica
schist, arkosic and granitic gneiss, quartzite and amphibolite. The
granitic rocks include some massive "granites" of quartz-diorite
composition and smaller lenses of granite and pegmatite. The phyllonite,
mica schist, and arkosic gneiss rocks are moderately to highly foliated
and anisotropic. On average, the foliation in the area of the tunnel
strikes N52°E east and dips 35° to the southeast.
|
| TBM Specifications : |
Robbins
Model 235-282
18-ft
cutterhead diameter
39 19-inch Disc Cutter (70,000 lbs max. cutter load)
2,954
hp cutterhead power
3,000,00
lbs total installed thrust
|
| Publications
: |
Kimball
R. W., Estep F. B., Easterling D., "Chattahoochee
Tunnel", RETC
2003.
|