Case Studies of 1,4-Dioxane Releases, Treatment, and Drinking Water Contamination - Environmental Investigation and Remediation - page 374

analyte list. The cleanup order for the case did not include either of the newly discovered contami-
nants, 1,4-dioxane or THF; however, there is a standard clause in Water Board cleanup orders
requiring that any investigations and i ndings conducted or obtained beyond the requirements of the
order be reported. The consultant and the facility operator fuli lled that requirement by reporting
the results, which completely changed the course of the cleanup.
The consequences of 1,4-dioxane discovery at this site included

• Increasing treatment operations

• Expanding the monitoring network by adding soil borings and 12 monitoring wells

• Adding additional analyses to the monitoring regimen

• Constructing a new off-site extraction trench

• Conducting a feasibility analysis for additional treatment capable of addressing 1,4-dioxane

The selected remedy was extraction of low-concentration 1,4-dioxane from an extraction trench
in the off-site plume and discharge under permit to the POTW. The fate of 1,4-dioxane in the POTW
and recycled water produced at the POTW was not evaluated, most likely because the POTW treats
in excess of 100 MGD (million gallons per day), whereas the discharge volume containing 1,4-diox-
ane is very small in comparison. The highest concentrations of 1,4-dioxane are handled together
with high-concentration VOCs by off-site disposal.

8.3 PALL/GELMAN SCIENCES INC., ANN ARBOR, MICHIGAN
Gelman Sciences Inc., acquired by Pall Life Sciences in 1997 (hereafter P/GSI), produced cellulose
triacetate i lters used in medical and other applications. As described in Chapter 2, 1,4-dioxane is used
for producing microporous cellulose i lters for scientii c and medical applications. In 1965, company
scientists began experimenting with a polymer called cellulose triacetate that had higher thermal sta-
bility and better chemical compatibility than any other membrane on the market. Because this poly-
mer was more stable, traditional solvents, like acetone, could not dissolve it to create pores. In 1966,
the company began using 1,4-dioxane to create a stronger solvent system (Fotouhi et al., 2006). In
1986, the company discontinued the use of 1,4-dioxane and phased out the line of i lters that required
its use in production. The line was eventually replaced by an improved i lter product. At the time that
P/GSI stopped using 1,4-dioxane, it was discovered that 30 private wells in the Scio Township area
were contaminated with 1,4-dioxane. Approximately 850,000 pounds of 1,4-dioxane was used to form
triacetate i lters during the 20 years before contamination was discovered (Fotouhi et al., 2006).
The P/GSI site has a long and complicated history that includes protracted legal disputes, complex
hydrogeology, a vociferous citizenry, and an evolution in regulatory requirements. Pall Corporation
(Pall) acquired GSI in 1997, well after the discovery and initial litigation of 1,4-dioxane contamina-
tion. P/GSI acquired GSI's environmental liability and has been engaged in an epic effort to contain
a multidirectional set of plumes that have migrated into developed neighborhoods.
The social equation inherent to cases of drinking water pollution often includes the obligatory
public l ogging of the responsible party in the local press, public meetings, and courts. In this case,
the currently responsible party is a company from New York that never handled 1,4-dioxane in
Michigan but acquired cleanup responsibility after the fact. The engineers at P/GSI, and the regula-
tors with the State of Michigan and Washtenaw County, together with scientists at the University of
Michigan, were pioneers who developed 1,4-dioxane analysis, treatment technologies, toxicological
proi les, and regulatory solutions to a massive 1,4-dioxane contamination problem. The P/GSI site
is the oldest and largest 1,4-dioxane contamination case in the United States.

8.3.1 W ASTEWATER D ISPOSAL
When Gelman Instruments, an early predecessor to P/GSI, moved to Scio Township, there were no
sanitary sewers available on-site. P/GSI explains that the Michigan Department of Natural