Engineering Inc. - May/June 2004 - 40

Thomas & Hutton Completes Design and Engineering of Georgia's First
Nanofiltration Facility in Just Five Months I n 1995, a series of tests
conducted at taminants would result in a 98 percent PROJECT: Moody Air
Force Base concluded that reduction in THMs. Moody AFB, Nanofiltration
Water groundwater wells used for drinking Immediately thereafter, USACE
and Treatment Plant water were at future risk of contami- Moody AFB
personnel joined Thomas & CATEGORY: nation. Georgia's Lowndes County
Hutton's design team on field visits to sev- Water and Wastewater was
experiencing rapid growth. An expand- eral nanofiltration and reverse
osmosis facili- FIRM: ing population meant increased demand on ties in
Florida. Their field research con- Thomas & Hutton Engineering Co. the
Upper Floridian aquifer. There was con- firmed the design team's
recommendations. CLIENT: cern surface water from surrounding rivers USACE
decided to move ahead quickly with U.S. Army Corps of Engineers, Savannah
and swamps might enter the aquifer via a the design of a nanofiltration
facility. District large number of limestone sinkholes, endan- Due to
federal budget constraints, the gering the water supply. nanofiltration
facility was slated for con- Of equal concern was the new EPA struction in
2001. To requirement placing strict limitations on Tri- accomplish this,
all halomethane THM levels. Formed when necessary permits had free
chlorine reacts with organic compounds to be in place prior to in the
source water, THMs are the most November 2002. If common group of
disinfection by-products. these deadlines could The EPA had concluded that
the presence of not be met, the proj- unacceptable levels of THMs in water
can ect was at risk of los- expose the population to higher risk for can-
ing its funding for a cer as well as other health and reproductive year or
more. defects. In addition to the current regula- A project of this tions
on THM levels, the EPA had proposed magnitude and com- a second stage of
even more restrictive limits plexity typically to take effect in the
future. requires 12 to 18 Based on these concerns, the Savannah months for
engineer- District of the U.S. Army Corps of Engi- ing and permitting.
neers USACE contracted with Thomas & Thomas & Hutton Hutton Engineering
Co. to do further was given only five analysis and provide a solution.
months. In 1999, Thomas & Hutton's initial Making matters research
confirmed levels of THMs that more complex, Geor- exceeded the proposed
EPA guidelines. A gia's Environmental minimum reduction of 75 percent in
THMs Protection Division would be needed based on worst-case EPD had never
scenarios. Traditional methods of conven- before permitted a tional
chemical treatment and filtration were nanofiltration facility. concept
from the project's outset all ruled out. Only nanofiltration or granular-
The design team the way through completion. Final activated-carbon GAC
could achieve the worked around the plans were submitted in October
desired reduction in THM levels. clock, knowing any delay could result in
the 2000 and EPD sent back its approval level In May 2002, Thomas & Hutton
pro- all-out failure of the project. This was a in short order, allowing
USACE and the vided USACE with a detailed life-cycle cost tremendous
challenge as the design and AFB program manager to secure the neces-
analysis of GAC and nanofiltration options. engineering of a high-pressure
membrane sary funding. The comprehensive review indicated that system is
extremely complex. Detailed con- Site construction was finished in spring
while the initial capital costs were about the trol schemes were essential
to ensure the var- 2002 and equipment was installed by July same, a
nanofiltration facility was substan- ious well pumps, chemical feed
systems, 2002. Start-up testing of the membranes tially less expensive to
operate over the long automated valves, process pumps, mem- and other
control systems took place over run. It required little operator input
other brane trains and other processes worked several months. The new
1,050 gallon-per- than routine quarterly maintenance. In together
seamlessly. minute nanofiltration plant has now been addition, its system
of forcing clean water At the same time, the Thomas & Hutton operational
for a year, producing excellent through the microscopic pores of a high-
design team set up a series of face-to-face water quality for the users of
the Moody pressure, polymer membrane to remove con- meetings with EPD to
review the design AFB system. 4 0 E N G I N E E R I N G INC. May l June
2004 A DV E RT I S I N G S E C T I O N
Engineering Inc. - May/June 2004

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