International Paper Riverdale Mill - Executive Summary
International Paper (IP) owns and operates the Riverdale Mill, an integrated pulp and paper mill, located in central Alabama about 10 miles east of Selma. As part of its' commitment to the environment, the Riverdale Mill converted the pulp bleaching process from elemental chlorine (i.e., chlorine gas, or Cl2) to chlorine dioxide (ClO2). IP has two ClO2 generators that create chlorine dioxide solution at 8.5 grams per liter (g/L) to 9.5 g/L. The generated ClO2 is then stored in three tanks before being used in the bleaching process. |
The U.S. EPA Risk Managment Program (RMP) regulates ClO2 when it is stored in solutions above 10 g/L (i.e., one weight percent) with a total mass of ClO2 greater than or equal to 1,000 pounds (lbs). The ClO2 processes at the Riverdale Mill have not reached a concentration of 10 g/L. However, IP has chosen to treat the ClO2 process as if the concentration is 10 g/L and thus has chosen to subject itself to the requirements of the Risk Management Program.
Please note that the Riverdale Mill has opted into the RMP program; based on the historical and current ClO2 operations, the Riverdale Mill is not regulated by the RMP program.
Because the Riverdale Mill is a pulp and paper mill and because the worst-case modeling impacts predict the potential for offsite consequences, Program 3 of the RMP is applicable. Program 3 requires both a worst-case modeling analysis and an alternative modeling analysis.
The worst-case analysis has release conditions explicitly specified by U.S. EPA. The chance of a worst-case release scenario occuring are very low. Quoting from the U.S. EPA General Guidance for Risk Management Programs (EPA 550-B-98-003), page 4-4,
Because the assumptions required for the worst-case analysis are very conservative, the results
likely will be very conservative. The endpoints specified for the regulated toxic substances are
intended to be protective of the general public. These endpoints ar
e concentrations below which
it is believed nearly all individuals could be exposed for one-half to one hour without any serious
health effects. In addition, the worst-case analysis is carried out using very conservative
assumptions about weather and release conditions. The distance to the endpoint estimated under
worst-case conditions should not be considered a zone in which the public would likely be in danger;
instead, it is intended to provide an estimate of the maximum possible area that might be affected
in the unlikely event of catastrophic conditions. ... EPA intends the estimated distances to provide
a basis for a discussion among the regulated community, emergency responders, and the public,
rather than a basis for any specific actions.
The worst-case release scenario for the Riverdale Mill is the complete rupture of the largest of the three ClO2 storage tanks. Based on that release combined
with the conservative parameters mandated by U.S. EPA, the radius to the endpoint distance includes schools, residences, prisons, recreational areas, and commercial areas. As noted above in the quote from U.S. EPA, the worst-case scenario represents the "maximum possible area that might be affected in the unlikely event of catastrophic conditions."
The alternative release scenario for the Riverdale Mill is a pipe leak. IP has installed numerous sensors in the ClO2 area to detect a ClO2 leak. IP expects that a pipe leak would be detected and eliminated within a five minute period. For the purposes of this analysis, a ten minute release duration is assumed. Based on average weather conditions at the site, the endpoint distance does not include residental population and reaches no public receptor with the exception of a small portion of a farmer's field. The residential population within that distance is zero. The radius does extend offsite, but the offsite areas it covers are o
nly the county road to the plant and a small portion of a farmer's field.
Safety is a very serious issue at IP. The Riverdale Mill is currently applying for OSHA VPP status, and IP complies with the requirements of the OSHA Process Safety Management (PSM) program. There have not been any ClO2 accidents during the last five years.
The Riverdale Mill is prepared to respond in case of an emergency. The Mill responds to both fire and hazardous material (HAZMAT) emergencies. As backup, the Mill also has written agreements for fire emergencies with the Selma Fire Department and for HAZMAT emergencies with the Prattville Fire Department. Both Selma and Prattville fire departments have copies of the Mill's emergency response plan.
While the possibility of an accident at the Riverdale Mill exists, the potential is low and IP takes preventive actions (through the OSHA prevention program and the emergency reponse program) to minimize any accident that might occur.