Project Challenge:
When several expansion joints in the Lime Reaction Tank (LRT)
walls and influent conduits fully ruptured during construction
of a deep aeration tank structure adjacent to the LRTs at the
Arlington County Water Pollution Control Plant, officials retained
Klein and Hoffman (K&H) to investigate, evaluate, and develop
a remediation method to halt the leakage. With one tank taken
out of service, due to the severity of the leakage, a timely
and efficient solution was required.
Project Solution:
K&H performed a field investigation and structural analysis
of each LRT structure which are comprised of (3) individual
2.2 million gallon tanks, configured in the shape of an "L",
with integral influent and effluent channels.
New steel strap plates were designed for all six tanks and installed
across the floor slab expansion joints to stabilize the tanks.
Repair details were developed for sealing the expansion joints
in the floor slab and walls. An expanding hydro active polyurethane
grout was injected into the actively leaking joints while the
adjacent tanks remained in operation. At locations with severe
leakage, temporary steel sheets were installed across the joints
to slow the leakage and contain the grout during pumping operations.
The steel sheets also forced the grout to form into a dense,
tightly bonded plug within the joints.
The tanks were successfully returned to operation and no longer
leak. The joints have been monitored by Arlington using crack
gages and field survey equipment since completion of the repair
work. The results of the monitoring show minimal joint and wall
movement, even during periods of filling and emptying of the
tanks, indicating that the strap plates have stabilized the
tanks and significantly decreased movement of the walls.
OWNER/CLIENT: Arlington County, Virginia
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