Confining layer

United States
Environmental Protection
Agency

C0„ Plume

¦V >2 . '

0„ Plum e

Through the Underground Injection Control
(UIC) program, EPA protects underground
sources of drinking water (USDWs) by
regulating the construction, operation,
permitting, and closure of injection wells that
are used for the underground storage or
disposal of fluids. Class VI wells are
specifically used to inject carbon dioxide
(CO2) into deep rock formations. The UIC
permitting authority reviews Class VI permit
applications to ensure that injected C02 will
remain within deep, isolated formations,
protecting human health and the environment.

- KEY

a

Site geology

Injection,
monitoring,
and other
wells

Drinking water
resource
protection
practices

— Water table

1	Thick, impermeable confining
layer prevents C02 from
leaking upward

2	Permeable injection formation
will hold injected C02

3	Testing shows that the fault
is inactive and sealed against
movement of C02

[ 4 | Water quality is tracked in the
permeable formation above
the confining layer using a
monitoring well

f~5~] Pressure and C02 in the injection
formation are tracked using a
monitoring well

[ 6 ] C02 injection well is permitted for safe [TT]
operation with many safeguards

[ 7 1 Cementing prevents C02 from moving
outside of the well

Well materials are corrosion-resistant



[~9~| Properly plugged and abandoned well

prevents CO movement between formations

12

Seismic activity is monitored
using surface equipment as
needed

Shallow groundwater well is
isolated from the injection
formation by multiple
impermeable layers

Seismic surveys are used to
study the geology and track
the location of C02 through
images of the subsurface

53

16

15

13

Safe C02 injection pressure
avoids damaging the injection
formation

Regular testing confirms the
physical integrity of the well

Injection pressure and flow
are continually monitored

Emergency response plan is
in place and ready to be
implemented

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