Superior Depropanizer and Storage Facility - Executive Summary

| Accident History | Chemicals | Emergency Response | Registration | Source | Executive Summary |

At the Superior Depropanizer and Storage Facility, we are committed to operating and maintaining our processes in a safe and responsible manner.  We use our accidental release prevention program in combination with the emergency response planning program to help ensure the safety of our employees, the public, and the protection of the environment.  This document provides a brief overview of the comprehensive risk management activities that we employ.  This document contains statements and information relating the following areas: 
*  A description of our facility and use of substances regulated by EPA's RMP regulation 
*  A summary of results from our assessment of the potential offsite consequences from accidental chemical releases 
*  An overview of our accidental release prevention program 
*  A five-year accide 
nt history for accidental releases of substances regulated by EPA's RMP rule 
*  An emergency response program 
*  An overview of planned improvements at the facility to help prevent accidental releases from occurring and adversely affecting our employees, the public, and the environment 
*  A management system to ensure RMP compliance 
The Superior Depropanizer and Storage Facility, owned and operated by Dome Petroleum Corp., a wholly owned subsidary of the BP Amoco Corporation, is located at 21st Street and Stinson Avenue in Superior, Wisconsin.  The facility has three basic functions.  Firstly, five 50,000-barrel storage spheres (V-2,3,4,5,6) provide break-out storage for natural gas liquids (NGL) shipped by Lakehead Pipeline.  Secondly, the depropanizer produces a commercial grade propane product (HD-5 specification) from this NGL feed-stock.  The butane/condensate mixture off the bottom of the depropanizer tower is returned to spher 
e V-1 for blending and continued shipping down Lakehead Pipeline.  Thirdly, propane from the depropanizer is stored in six bullets and distributed to local markets by means of the truck loading facility. 
In our process, we use the following substances that EPA has identified as having the potential to cause significant offsite consequences in the event of a substantial accidental release: 
There are no listed toxic substances above threshhold quantities. 
The following is a complete list of listed flammable substances at this facility.  The alkane hydrocarbons constitute the products that we handle and process.  The ethyl mercaptan is the odorizing agent we inject into the sales propane, which is subsequently sold commercially. 
       Substance and CAS No. 
       Ethane        74-84-0 
       Propane        74-98-6 
       Isobutane        75-28-5 
       Butane        106-97-8 
       Isopentane    78-78-4 
       Pentane        109-66-0 
       Ethyl Mercaptan    75-08-1 
Our accidental release prevention program and our contingency planning eff 
orts help us effectively manage the potential hazards that are posed to our employees, the public, and the environment by our handling of these substances. 
EPA's RMP rule requires that we provide information about the worst-case release scenarios and alternative release scenarios for each process our facility.  The following are brief summaries of these scenarios, including information about the key administrative controls and mitigation measures to limit the exposure distances for each scenario: 
Worst-case Release Scenario - Regulated Toxic Chemicals 
There are no listed toxic substances at the Superior Depropanizer and Storage Facility. 
Alternative Release Scenario - Regulated Toxic Chemicals 
There are no listed toxic substances at the Superior Depropanizer and Storage Facility. 
Worst-case Release Scenario - Regulated Flammable Chemicals 
The RMP rule specifies that we identify the greatest quantity of a flammable mixture from a  ves 
sel or from a pipe and calculate the distance to an endpoint of 1 psi overpressure resulting from a vapor cloud explosion of that quantity.  In this case, the contents of one storage sphere at maximum controlled  inventory represent this greatest quantity, i.e., 8,640,000 pounds of natural gas liquids.  The maximum inventory in any sphere is limited by site operating procedures and control devices to 92.8% of total volumetric capacity.  The calculated hazard distance for this worst case scenario is 1.7 miles. 
Alternative Release Scenario - Regulated Flammable Chemicals 
The alternative scenario selected involves the rupture of a loading hose at the propane  truck loading facility.  The scenario assumes that the loading hose ruptures, that the driver does not initiate the emergency shut-down (ESD), that the excess flow valve fails, and that the maximum flow from the loading pumps, 400 gpm, continues until the release is isolated two minutes later when the area gas detectors initiate an  
ESD.  The released mass under this scenario would amount to 3200 pounds of propane, all of which was assumed to be involved in a vapor cloud explosion.  The endpoint distance to a 1 psi overpressure is 420 feet. 
We use this information in the development of our site and community emergency response plans which attempt to address all reasonable contingency cases. 
The process at Superior Depropanizer and Storage Facility, which is regulated by the Environmental Protection Agency's (EPA's) risk management program (RMP) regulation, is also subject to the Occupational Health and Safety Administration's (OSHA's) process safety management (PSM) standard.  The document which outlines the accident prevention program in use by Dome Petroleum Corp. is the Process Safety Management Performance Baseline, Rev. 0, 5/31/94.  A management of change is currently under review t 
o modify this document to incorporate all the requirements of the EPA's RMP regulation.  This Performance Baseline document is summarized in the Prevention Program report (not submitted) and covers the following required elements: 
*  Process safety information (PSI) 
*  Process hazard analysis 
*  Operating procedures 
*  Training 
*  Mechanical integrity 
*  Management of change 
*  Pre-startup review 
*  Compliance audits 
*  Incident investigation 
*  Employee participation 
*  Hot work permit 
*  Contractors 
The principal hazards associated with the substances at the Superior Depropanizer and Storage Facility are fire and explosion and pressurized equipment.  Systems maintained here that contain or control the hazards associated with the substances handled include: 
*  Smokeless flare system 
*  Process relief valves and rupture disks 
*  Automated isolation valves 
*  Manual isolation valves 
*  Diking around each storage sphere 
Redundant process, control, and safety equipment 
*  Emergency generator 
*  Uninterruptible Power Supply (UPS) 
*  Continuous monitoring for detection of the presence of atmospheric hydrocarbons 
*  Continuous monitoring for detection of fire 
*  Video surveillance 
Mitigation systems include: 
*  Fire water system, including a large 2,310,000-gallon pond reservoir and monitors 
*  Fire water sprinker system 
*  Fire extinguishing equipment 
*  Emergency response training for all plant personnel 
*  Emergency response plan co-ordinated with municipal responders 
*  Personal protective equipment required for workers on site 
We keep records for all accidental  releases that occur at our facility.  The following is a brief summary of the two accidental releases involving materials covered under EPA's RMP rule during the past five years at this facility: 
June 21, 1995.  Release of Ethyl Mercaptan 
The day was very warm and because of this the pressure in  
the ethyl mercaptan day tank rose above the set point of the relief valve on the tank.  Ethyl mercaptan was released into the flare system and odor was released through the flare stack.  There existed no danger but the presence of the odor generated much concern and as a result there were numerous public complaints.  The investigation revealed that the relief valve was set unnecessarily low at 14 psi.  It was reset to 75 psi, well within the rated pressure of the tank.  There has been no similar release since that time. 
September 8, 1998.  Sphere V-6 NGL Vapor Release 
One of the two atmospheric pressure relief valves on NGL sphere V-6, together with its associated rupture disk, relieved prematurely, resulting in a release of an estimated 27,000 pounds of NGL vapor.  The incident investigation revealed several possible root causes but could not determine with confidence which single cause or combination of causes initiated the event.  As a result of this fact, each identified potential 
root cause has been addressed.  In addition, local authorities had specific concerns and each of these has also been addressed to their satisfaction. 
We maintain a written integrated contingency plan, which consolidates all of the applicable federal, state, and local regulatory requirements for emergency response planning.  Our program provides the essential planning and training for effectively protecting workers, the public, and the environment during emergency situations.  Furthermore, we coordinate plans with the community emergency response planners, which for us primarily involves establishing response plans with the Superior Fire Department.  Public notification procedures are in place.  A summary of the Dome Petroleum Corp. Emergency Procedures Guide, 5/1/1997, constitutes the Emergency Response Plan report (not submitted).  The Guide is organized as follows: 
*  Section 1 Immediate Action 
*  Section 2 Table of Contents 
*  Section 3 Organiz 
*  Section 4 Emergency Response 
*  Section 5 Duties and Responsibilities 
*  Section 6 Specific Functions 
*  Section 7 External Resources 
*  Section 8 Recovery 
*  Section 9 Emergency Preparedness 
*  Section 10 Administration 
The following is a list of improvements that we are planning to implement at the facility to help prevent and better respond to accidental releases: 
Because of the proximity to process equipment of one of the two flare stacks, the two flare systems will be integrated into one and the flare of concern will be decommissioned. 
An upgrade to the control system is currently underway.  The new system will allow us to bring in several times the number of monitoring points and is a much faster system, giving better real-time process information. 
We are currently investigating with Lakehead Pipeline whether an isolation of NGL into our plant from their piepline should be initiated on sphere pressure lower than the curr 
ent setting. 
We are in the process of installing an open path infrared gas detection system for perimeter gas monitoring. 
Richard Boyer, the area foreman, has the responsibility for ensuring that our facility operates in a safe and reliable manner.  This responsibility includes overseeing the implementation of the elements of our risk management program.  To ensure that our risk management program is appropriately developed and implemented, Richard has been assigned the role of PSM/RMP Coordinator.  The PSM/RMP Coordinator, acting with the authority delegated directly from the area superintendent, Larry Jardine, has the responsibility for the development, implementation, and integration of the EPA RMP elements and the elements of OSHA's PSM program (where applicable) as required under Section 68.15 of the RMP rule.  There are several resources from throughout the BP Amoco organization that have provided assistance in the preparation of this Risk Management 
Plan.  The RMP Management System report (not submitted) details the person assigned to each area of responsibility.
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