This is the 8th report by Harold
Cunliffe
.
NANCY
CREEK TUNNEL
Report
as of
May 7, 2004
This
is the eighth Report from Harold Cunliffe, the NUP – B appointee to the Nancy
Creek Tunnel Technical Advisory Committee (NCTAC). Should you wish to receive
the first seven, please e-mail me with your request.
Please also feel free to pass this onto interested neighbors and groups. As
before, I am reporting events to the best of my recollection and I will try to
differentiate when I am offering an opinion. This Report may not be the position
of the NCTAC nor the City of
Atlanta
.
First,
let me remind you of some names and dates. The contractor, Nancy Creek
Constructors (NCC), was issued a Notice to Proceed on
July 15, 2002
. Work has been progressing since then. The City of
Atlanta
entered into a Consent Decree with the Environmental Protection Agency and a
subsequent amendment extended the substantial completion to
December 31, 2005
. The contract with NCC requires a substantial completion date by
October 26, 2005
. The Nancy Creek Tunnel is scheduled to be “open for business” on
January 24, 2006
.
To
date, the Tunnel Boring Machine (TBM) that was launched from the R. M. Clayton
Shaft has progressed 19,435 feet or 74% of the way to the Roswell Shaft. The TBM
that began its journey at the Roswell Shaft has progressed 15,061 feet or 92% of
the way and should arrive at the Johnson Ferry Shaft within two – three weeks.
As of this date, it is directly beneath
Evergreen Drive
. There are several Intake Tunnels that connect the existing trunk sewer main to
the Tunnel. Work has begun on two of these connecting tunnels. My analysis of
the project is that it is two months ahead of schedule, but the project managers
would rather think that the time allowance for unforeseen contingencies is now
“just tolerable”.
Jordan,
Jones and Goulding, the project engineers report
that the rock conditions have been better than expected. Overall, few fissures
and little broken rock have been encountered. An exception to this was a 30 foot
wide fracture zone encountered just north of
Windsor Parkway
. When the Tunnel went through this zone, the water table was lowered thus
drying up a spring and creek some 1,000 feet away. Currently, water is being fed
into the creek with a garden hose while a solution is being sought. Jordan,
Jones and Goulding warn that soon the R. M. Clayton
TBM will be encountering rock in the vicinity of
Chastain
Park
where the drill logs indicate extensive fractured rock. Exploratory holes will
be drilled ahead of the TBM. Where ground water flow is detected, grout will be
injected to mitigate groundwater migration into the Tunnel.
Please
e-mail questions that are of general interest and they will be answered next
Report.