Office of
United States Ground Water and
^1 Environmental Protection Agency Drinking Water

CLASS V UIC STUDY FACT SHEET
SPENT BRINE RETURN FLOW WELLS
What is a spent brine return
flow well?
Spent brine return flow wells are used to dispose of brines from which minerals, halogens, and
other compounds have been extracted. These wells are commonly associated with manufacturing
facilities that produce specialty chemicals such as boron, bromine, magnesia, or their derivatives.
What types of fluids are
injected into spent brine
return flow wells?
The chemical characteristics of the injected spent brine are determined primarily by the
characteristics of the brine that is withdrawn for processing and the nature of the extraction and
production processes used. In general, the chemical composition of the spent brine is similar to
that of the produced brine except that the concentration of target elements (e.g., magnesium) has
been reduced and the concentration of other elements (e.g., calcium) may have been increased
through substitution.
Do injectate constituents
exceed drinking water
standards at the point of
injection?
Available data indicate that concentrations of barium and boron in spent brine routinely exceed
primary drinking water standards and health advisory levels in AR. Data available for MI
facilities indicate that chloride, copper, iron, manganese, total dissolved solids, and pH levels
frequently exceed secondary drinking water standards. Data are not available to determine
whether concentrations of some other constituents, including some heavy metals, are present at
concentrations above health-based levels.
What are the characteristics
of the injection zone of a spent
brine return flow well?
Spent brine return flow wells inject spent brine into the same formation from which it was
withdrawn, which, in all current cases, is below the lowermost underground source of drinking
water (USDW). (In fact, most spent brine return flow wells were initially drilled as production
wells and subsequently converted to injection wells.)
Are there any contamination
incidents associated with spent
brine return flow wells?
No incidents of USDW contamination by spent brine return flow wells have been reported.
Are spent brine return flow
wells vulnerable to spills or
illicit discharges?
Spent brine return flow wells are not likely to receive accidental spills or illicit discharges.
How many spent brine return
flow wells exist in the United
States?
There are 98 documented spent brine return flow wells that are regulated as Class V injection
wells. There are other spent brine return flow wells in the United States that are currently being
regulated as Class II or III wells (in NY, TN, CA, and OK).
Where are spent brine return
flow wells located within the
United States?
Documented Class V spent brine return flow wells are located in AR (74) and MI (24).
How are spent brine return
flow wells regulated in states
with the largest number of
this type of well?
Individual permit. AR, MI
Where can I obtain additional
information on spent brine
return flow wells?
For general information, contact the Safe Drinking Water Hotline, toll-free 800-426-4791. The
Safe Drinking Water Hotline is open Monday through Friday, excluding federal holidays, from
9:00 a.m. to 5:30 p.m. Eastern Standard Time. For technical inquiries, contact Amber Moreen,
Underground Injection Control Program Office of Ground Water and Drinking Water (mail code
4606), EPA, 401 M Street, SW, Washington, D.C., 20460. Phone: 202-260-4891. E-mail:
lno reen. alliber V/ epa. go\ . The complete Class VUIC Study (EPA/816-R-99-014, September
1999), which includes a volume addressing spent brine return flow wells (Volume 9), can be
found at http://www.epa.gov/OGWDW/uic/cl5study.html.

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