January/February 2023 - 99

A regular column showcasing successful
best practices for sustainable foundations
FOUNDATIONS FOR A SUSTAINABLE FUTURE
recovered water. This solution allowed
for continuous jet grouting operations
without the need to wait for spoils to
solidify in pits. It also allowed recovered
water to be reused in the jet
grouting process. At the end of the
project the jet grout water was pure
enough to discharge into the sanitary
sewer rather than hauled to a treatment
plant, as is typically the case.
The Results
Saving Water in Spoils Separation
The Challenge
The Sacramento River East Levee
Contract 2 (SREL 2), a U.S. Army Corps of
Engineers project in Sacramento,
California, awarded a contract to process
jet grout spoils. A standard jet grout
cutoff wall project would utilize large
earthen pits, built exclusively for the
purpose of dumping jet grout spoils.
These would be allowed to harden and
set over time. Then they would be
excavated as solid jet grout spoils and
sent to disposal with the pit then reused.
The process of dumping, hardening and
excavating a single pit can take up to
several days, therefore a single project
requires multiple pits to ensure continuous
operations. Most of the water
used in a jet grout cutoff wall is considered
" single use. " The wastewater
from this process is often high in pH and
requires additional processing at a
wastewater facility before it is considered
safe for environmental release.
Credit: Goettsch Partners
Because the work area in Sacramento
did not have sufficient space to
build jet grout spoil pits, an alternative
solution was required. The alternative
would need to be capable of processing
100% of the spoils from the jet grouting
operation and providing a stackable dry
solid that would be accepted at the local
disposal. While sustainability was not
the primary driver in the solution it was
a very important secondary benefit.
The Solution
The contractor's jet grout spoils system,
along with its prescribed chemistry,
were deployed to the project. The
system received contaminated grout
spoils from the jet grouting operation
and separated the free water from the
jet grout solids. This chemistry was
added to the process at different points
not only to improve the separation
capabilities of the system, but also help
remediate any contamination in the
AUTHORS Brandon Connolly, Stage 3 Separation
DEEP FOUNDATIONS * JAN/FEB 2023 * 99
By utilizing this particular jet grout
spoils system, the customer not only
improved its uptime efficiency and
reduced overall downtime, but also
impacted the carbon footprint of the job
by reducing the number of dump trucks
and vacuum trucks by 40%.
Sustainability in industry should
not only be measured in carbon footprint,
however, and should also concern
water management practices. The
separation jet grout spoils system used
on the Sacramento project recovered
more than 2,160,000 gal (8,200,000 L) of
water, which was reused in the jet
grouting process and eventually discharged
at the local sanitary sewer for
reuse by the general population. This is
the equivalent of at least 51,000 full
bathtubs or three and a half Olympic
swimming pools!
This project recovered more than 2.1 million
gallons of water-enough to fill three and half
Olympic pools.
http://centerrock.com/
January/February 2023

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