Environmental Engineering Reference
In-Depth Information
Fiber-optic cables are connected to allow automated operation and control from the integrated
control systems in place for the GWTP operations. These systems allow remote monitoring and
operation of the system. Inl uent and efl uent water samples will be collected and analyzed to pro-
vide assessment of the system's operational effectiveness during the 30-day start-up phase, antici-
pated to be in May 2009. Optimization of the system will occur during the initial week of operations,
while both treatment systems are operated in series. This approach ensures that TCE treatment will
be performed as before, regardless of the performance of the HiPOx system. Once effective removal
is verii ed, the air strippers will be bypassed, and the system will be operated for an additional test
period of 30 days, before turning the system over to the Operation and Maintenance Contractor at
the facility for long-term operations.
8.7.8 C
OST
A
NALYSIS
Operating the new AOT system instead of using the existing air strippers will result in an annual
electrical cost reduction of $25,000. Additionally, the elimination of the air-stripper systems will
save $25,000 in sulfuric acid neutralization costs, $10,000 in GAC cost, and $30,000 in evaporative
water loss per year. However, operating the HiPOx system will add $60,000 in peroxide cost and
$5000 in the generation of oxygen for ozone production. The AOT upgrade represents a net overall
savings of approximately $25,000/year in materials and electrical costs for water treatment. In addi-
tion, the new treatment plant replaces the aging air strippers with new equipment and has fewer
moving parts; hence, future maintenance costs will be reduced. The existing air strippers are over
20 years old, and maintenance costs are increasing over time as the system has exceeded its 15-year
designed life expectancy. The new system is also modular and therefore capable of being relocated
and reused at another location in the future.
8.7.9 F
UTURE
P
LANS
Long-term operation and maintenance of the HiPOx system will begin in 2009 and may continue
for decades, given the scale and levels of remaining TCE, DCE, and 1,4-dioxane contamination in
the regional groundwater. The Phase II FRI includes the following:
•
Drilling and installing wells to better dei ne the nature and extent of 1,4-dioxane contami-
nation in three dimensions in the regional aquifer
Groundwater modeling to understand the migration potential and patterns, as well as the
•
potential for human exposure to 1,4-dioxane
All steps in the Phase II FRI are expected to be completed by the spring of 2010. Ongoing moni-
toring of the KMnO
4
pilot-test areas will focus on identifying the distribution of 1,4-dioxane (in
low-permeability units present in the saturated zone) and will specii cally look for 1,4-dioxane
trapped in pores as well as for evidence of chemical oxidation of 1,4-dioxane. A bench-scale KMnO
4
oxidation test for 1,4-dioxane begun in spring 2008 involved extraction of contaminated groundwater
from the site, treatment of one set of bottles with KMnO
4
, acidii cation of another set of bottles to
eliminate possible biodegradation, and use of an untreated control. These triplicate sets will be sac-
rii ced quarterly for several years to assess the impact of KMnO
4
on 1,4-dioxane concentrations.
Initial results from the i rst quarter indicate 13% greater reduction in 1,4-dioxane concentration in the
KMnO
4
-spiked bottles. Planned future studies include assessment of the biological communities
native in the groundwater to determine if any bacteria capable of degrading 1,4-dioxane are present
in the aquifer and to identify any applicable amendments with the potential to stimulate the biological
communities for more effective degradation.
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