Weyerhaeuser Company, Flint River Operations - Executive Summary
CORPORATE COMMITMENT |
Weyerhaeuser Company's Flint River Operation (Weyerhaeuser FRO) has a basic commitment to responsible stewardship of the environment, protection of the community, protection of employee health, and assurance of product safety that extends to the processes covered by Risk Management Program (RMP) requirements. Weyerhaeuser FRO has developed management systems in compliance with various applicable regulations to prevent the release of regulated substances especially in locations that may cause detrimental effects to employees, the community, or the environment. This is accomplished through a systematic evaluation of process design, process technology, operational procedures, maintenance activities, non-routine procedures, emergency preparedness, training, and several other factors.
Weyerhaeuser FRO has a long-standing commitment to worker and public safety. This commitment is demonstrated by the resources invested in accident prevention, such as training personne
l and considering safety in the design, installation, operation, and maintenance of the facility's processes. Weyerhaeuser FRO's policy is to implement reasonable controls to prevent foreseeable releases of regulated substances. However, if a release does occur, trained personnel will respond to control and contain the release.
Weyerhaeuser FRO plans to meet or surpass all regulatory requirements. In the attempt to accomplish this goal, the management systems at this facility have been developed in such a way that the hazards are identified, understood, and controlled to prevent accidents. The RMP regulated chemicals include chlorine dioxide and chlorine.
The Flint River Plant produces bleached communition (fluff) pulp from cellulose fiber using the Kraft process. The plant is organized into five main units encompassing several operational process areas. The five units include: the woodyard and water/wastewater treatment; pulping, which includes chip digestion, o
xygen delignification, and bleaching operations; pulp finishing; utilities, which includes steam/power generation and chemical recovery; and plant maintenance. A brief description of the production process is provided below.
Roundwood (logs), purchased wood chips, and woodwaste fuel (bark) are received and processed by the woodyard. Major woodyard operations include debarking, chipping, and screening for thickness and sizing. The pulping operation includes chip digesting with chemicals (liquors) and steam, brownstock diffussion washing and screening, and reaction with oxygen to dissolve lignin that holds the cellulose fibers of the wood chips together. Whitening of the delignified pulp is accomplished in the bleaching sequence. The bleached pulp is then formed, dried, cut into small rolls, wrapped, weighed and then shipped off-site.
The primary functions of the utilities unit include: cogeneration of electricity, generation of compressed air and chilled water for the plant, regenerat
ion of white liquor, recovery of lime, and combustion of non-condensable (TRS) gases. The major emission units in the utilities are a bark boiler, recovery boiler, smelt dissolving tank, and calciner. Raw river water and well water are treated on-site for use in the utilities unit and wastewater generated by the plant is treated prior to surface discharge to the Flint River.
REGULATED SUBSTANCES AND PROCESSES
Weyerhaeuser FRO operates two processes that have more than a threshold quantity of a regulated substance. The two processes are:
1) Chlorine dioxide generation and storage: The largest chlorine dioxide solution tank at the facility has a maximum capacity of 491,000 gallons. The maximum working volume in the tank is administratively controlled to a maximum capacity of 220,000 gallons. The chlorine dioxide concentration in solution can be as great as 11 g/L. This is equivalent to about 20,381 lb of chlorine dioxide.
2) Water treatment: This process utilizes chlorine stored in 1
-ton cylinders. The maximum amount stored in one area is four cylinders.
Both of the above processes are regulated under RMP Program 3.
Weyerhaeuser FRO has developed and implemented an accidental release prevention program to continuously comply with OSHA's 29 CFR 1910.119, Process Safety Management of Highly Hazardous Chemicals and EPA's 40 CFR Part 68 Subpart D, Accidental Release Prevention provisions in the Risk Management Program. The prevention program thus developed and implemented consists of twelve elements which are listed below.
7 Process safety information.
7 Process hazard analysis.
7 Operating procedures.
7 Mechanical integrity.
7 Management of change.
7 Pre-startup review.
7 Compliance audits.
7 Incident investigation.
7 Employee participation.
7 Hot work permit.
Some elements of the prevention program are intended to ensure that designs are reviewed so that any new processes and/or equipment are in conformance to saf
e design principles. The remainder of the elements ensure that normal operation, maintenance and control of hazards prevent inadvertent changes outside the safe design and operating envelope.
Weyerhaeuser FRO's processes and procedures are in line with US EPA's assessment that, "Prevention of accidental releases requires a holistic approach that integrates technologies, procedures, and management practices." Therefore, Weyerhaeuser FRO's prevention program is designed to provide for ongoing management of highly hazardous substances. It is not a list of "once and done" actions. Rather it provides a means for assuring safe operations throughout the life of the facility. To this end, Weyerhaeuser FRO utilizes modern computer management techniques in coordination with plant-wide awareness to ensure continued fulfillment of prevention requirements.
FIVE-YEAR ACCIDENT HISTORY AT WEYERHAEUSER FRO
Weyerhaeuser FRO has an outstanding record of accident prevention over the past five year
s. This good record is demonstrated by the lack of any accidental release which had offsite consequences over the past five years and by Weyerhaeuser FRO's achievement of OHSA's VPP STAR award. However, as presented in this RMPlan, Weyerhaeuser FRO is reporting two on-site accidents involving contract employees during 1994. It should be noted that due to the lack of records some of the data reported for these two accidents are estimates that have been provided only to fulfill the requirements of RMP.
The hazard assessment evaluates the offsite consequences of accidental releases on public and environmental receptors. Pubic receptors are offsite residences, institutions (such as schools and hospitals), commercial and office buildings, parks, or recreational areas inhabited or occupied by the public at any time where members of the public could be exposed to toxic concentrations, radiant heat, or overpressure, as a result of an accidental release. Environmental re
ceptors are natural areas such as national or state parks, forests, or monuments; officially designated wildlife sanctuaries, preserves, refuges, or areas; and federal wilderness areas, that could be exposed at any time to toxic concentrations, radiant heat, or overpressure greater than or equal to the endpoints in the risk management program rule, as the result of an accidental release.
This section describes the worst-case consequence analysis and alternate scenario consequence analyses. These analyses comprise the hazard assessment.
WORST-CASE RELEASE SCENARIO ANALYSIS FOR A TOXIC SUBSTANCE RELEASE
The worst-case release scenario for a toxic substance at Weyerhaeuser FRO is a hypothetical release of the entire contents of the largest storage vessel of chlorine dioxide solution, which is administratively controlled to 220,000 gallons. The entire 220,000 gallons is assumed to be released in ten minutes. Weyerhaeuser FRO considers such an event to have an extremely small probabili
ty of occurrence and, thus, to not be of practical interest in terms of risk management and emergency response planning. Therefore, such a scenario is included in the Risk Management Plan for purposes of administrative completeness.
Under EPA's Accidental Release Prevention Program (ARPP), as mandated by Section 112(r) of the Clean Air Act Amendments of 1990, facilities that store toxic chemicals in quantities exceeding regulatory threshold limits must evaluate the offsite impact of "worst-case" releases as part of the facility's risk management plan (RMPlan). The RMP regulations consider chlorine dioxide (ClO2) to be a "toxic gas." "Worst-case" release scenarios for toxic gases are based upon the assumption that all the gas in a container or process is released to the atmosphere during a 10-minute period. In its RMP guidance EPA made special provision for a number of gases which are dissolved in water solutions. Examples include aqueous ammonia, hydrochloric acid, hydrofluoric a
cid and aqueous formaldehyde. Toxic gas emissions from "worst-case" spills of these water solutions are assumed to occur over a 10-minute period. No provision was made, however, for ClO2 water solutions even though this is the most common form for the storage and use of this chemical.
Since ClO2 is stored as an approximately 1 percent liquid solution at paper mills, ENSR has developed a method for considering the emission of ClO2 from "worst-case" spills of these solutions. This methodology is presented in ENSR's February 1998 report to Weyerhaeuser entitled "Final Report: Modeling of Chlorine Dioxide Emission Rates and Off-Site Consequences Related to Accidental Spills" (Document Number 7263-042-410). Evaporative emissions from confined spills are calculated by use of a spreadsheet version of the Monsanto/CMA spill model (References 5 and 6). Evaporation from other sources such as the sewers is calculated by use of the EPA WATER8 model.
Using the emission rate calculated from t
he above referenced methodology as input, the SLAB computer model (Lawrence Livermore Laboratory, 1990) was used to estimate the downwind concentrations under the EPA-mandated weather conditions of 1.5 meters per second wind speed and F stability. These low dispersion conditions occur at night with fair skies. Passive mitigation measures were considered for this hypothetical release. The toxic endpoints for toxic substances have been set by EPA in the regulation. These values are generally equivalent to Level-2 Emergency Response Planning Guidelines which the American Industrial Hygiene Association define as the concentrations below which exposure for up to an hour will not result in irreversible or escape-impairing health effects. For the worst-case release scenario at Weyerhaeuser FRO, the SLAB model predicted a maximum distance of 14.9 miles to the chlorine dioxide toxic endpoint of 1 ppmv. Figures and additional information on this release scenario are provided in Section 2.
ALTERNATE RELEASE SCENARIO FOR CHLORINE DIOXIDE GENERATION AND STORAGE PROCESS
The chlorine dioxide storage vessels have a drain valve located near the bottom of each tank. This alternate scenario assumes that an 8" plug valve is left 100% open, or fails while 100% open. Based on the valve being open, the chlorine dioxide solution tank being at a level of 40 feet, the control valve equation and the assumption that 10 minutes will elapse before the release is detected and stopped by closing the valve, approximately 66,190 gallons of chlorine dioxide solution could be released. The emission rate was calculated in the same manner as the worst-case release scenario.
The SLAB computer model was used to estimate the downwind concentrations under the weather conditions of 3.0 meters per second wind speed and D stability. Passive mitigation of the release was considered. The SLAB model predicted a maximum distance of 2.87 miles to the chlorine dioxide toxic endpoint of 1 ppmv. Figures and
additional information on this alternate release scenario are provided in Section 2.
ALTERNATE RELEASE SCENARIO FOR CHLORINE WATER TREATMENT PROCESS
Mill supply water and wastewater are treated with chlorine in the water treatment and wasterwater treatment plants. The water treatment plant is located east of the mill near the Flint River. The wastewater treatment plant is located northeast of the mill near Goose Creek. Chlorine is stored in and used from 1-ton chlorine cylinders located at each of the treatment plants. Chlorine cylinders are connected in pairs, one pair near the river supply pumps and one pair at wastewater treatment. Only one cylinder of each pair is used, and when it is empty the system switches to the other cylinder.
This scenario is a leak in one of the 1-ton chlorine cylinders at the water treatment plant. The impact from a release from one of these cylinders encompasses a larger off-site area than a release at the wastewater treatment plant. The release is
assumed to occur as a result of a fusible plug failure due to corrosion. Using the orifice equation results in a chlorine release rate of 163 lb/min. No active or passive mitigation is assumed. EPA's RMP Offsite Consequence Analysis Guidance was used to estimate the distance to the EPA toxic endpoint, which is 0.23 miles. A graphical representation of this alternate scenario is shown in Figure 11, and additional information is also provided in Section 2.
EMERGENCY RESPONSE PROGRAM
Weyerhaeuser FRO maintains a comprehensive written emergency response program to protect plant workers, the general public and the environment. The program includes plans and procedures for responding to a wide range of events, caused either naturally or accidentally, which have the potential to result in a release of a regulated substance. Weyerhaeuser FRO's emergency response program utilizes the Incident Command System (ICS) which parallels the National Interagency ICS. This is an "all risk" system
developed for on-scene management of any emergency event. The functional design of the ICS minimizes the impact of personnel changes upon the emergency plan. Periodic emergency drills are conducted within the plant to maintain preparedness and to identify areas for improvement. The emergency response program is updated when necessary, based on modifications made to the plant processes or facilities. In addition, the plant has an emergency preparedness program that addresses maintenance, inspection and testing of response equipment as well as instructions and training that govern use of this equipment.
The overall emergency response program is coordinated with the Local Emergency Planning Commission (LEPC). This coordination includes periodic meetings of the committee, which includes local emergency response officials, local government officials, and industry representatives. Weyerhaeuser FRO has around-the-clock communications with the County Sheriff's office (county communicat
ion point of contact) and the LEPC to ensure notification of the public in event of an incident, if necessary, as well as facilitating a quick response.