CO2 sequestration is also known as "CCS" or "GCS" - for geological carbon sequestration.
Risks to our drinking water -The following quotes come the article linked at the end of this posting.
"There are several potential scenarios by which a USDW may be impacted by GCS activities. Potential pathways include upward migration, fractured cap rock, faults, trace contaminants included in the CO2 stream, a microannulus outside the final casing, and the mobilization of metals from native minerals."
"The success of GCS relies on the structural integrity of confining units, for trapping CO2 in underlying permeable formations. Injection of CO2 into the receiving aquifer has the potential to cause deformation, trigger seismicity, reactivate faults, and compromise seals in wells. Each of these processes could increase the risk of leakage jeopardizing containment and the protection of groundwater quality."
"Risk is typically defined as the product of the probability of occurrence of an event and the negative consequence of the event. There are concerns that there is limited likelihood data concerning the consequences of GCS, which might result in either over or underestimation of chances of occurrence. Water purveyors take pride in meeting their mandate to protect the public health by providing safe clean drinking water.Read the full article here
While the probability of a USDW being significantly impacted may be low, the negative consequences of any such incident have the potential to be very high. The proposed rule requires operators of GCS facilities to provide financial assurances adequate for corrective actions, plugging and abandonment of wells, post injection site care and closure, and emergency response for failed injection wells. The question of how to structure liability for long-term risks to USDWs associated with the geologic sequestration of CO2 has not yet been resolved."