Roundup Natural Gas Liquids Extraction Facility - Executive Summary

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This executive summary is a brief overview of the Risk Management Program and the associated policies at the Public Service Company of Colorado (PSC) Roundup Natural Gas Liquids (NGL) Extraction Facility. 
 
Prevention and Response Policies 
The accidental release prevention and emergency response policies are represented in the Emergency Planning and Response Sections of the Roundup PSM/RMP manual for the LPG, drip gas, and propane system. PSC takes an active role in preventing accidental releases at all of its facilities by ensuring that its employees are properly trained in the safe operation of covered processes and the safe handling of regulated chemicals.  As for emergency response, PSC has established and maintained procedures for emergency notification and response.  These are reviewed with employees on a periodic basis and revised to accommodate changes in staffing when they occur. 
 
PSC management understands its duty to provide a safe working environment and to take measures to  
prevent accidents that may have an effect on the surrounding community.  This understanding is reflected in procedures described and referenced in the PSM/RMP manual.  Additionally, PSC has determined that, despite qualification for Program 2 compliance, it is prudent to establish and maintain Program 3 compliance as a conservative safety and business approach. 
 
Stationary Source and Regulated Substances 
Roundup is a natural gas liquids extraction facility designed to process 40 mmscfd of natural gas.  The purpose of the Roundup NGL Extraction Facility is to reduce the dew point of the gas to a level that is acceptable for pipeline transmission.  Control of the dew point is critical since the incoming gas is water-saturated in many cases.  The dew point increases as the concentration of moisture (water and heavy hydrocarbons) in the inlet gas increases.  As gas flows through the pipeline, its temperature will decrease to about the same temperature as the surrounding ground.  If this te 
mperature is below the dew point of the gas, the water and heavy hydrocarbons will tend to condense.  The resulting buildup of hydrates can begin to restrict process flow, particularly at orifices and bends in the pipe.  In extreme cold, the hydrates may even form a potentially dangerous ice plug. 
 
In order to reduce the dew point of the gas (and accordingly, minimize the formation of hydrates), the inlet gas is chilled using a propane refrigeration system.  This process allows the heavy hydrocarbons and water to condense out of the process flow.  Ethylene glycol is spray-injected into the inlet gas at each heat exchanger to absorb the condensed water.  Ethylene glycol, condensed liquid hydrocarbons, and residue gas are then separated in a cold separator.  The lower the temperature in the separator, the greater the volume of liquid extracted, which also lowers the dew point of the residue gas.  The ethylene glycol is circulated through a reboiler to drive off condensate, and then it is 
circulated to the separator.  Condensed hydrocarbons are then stored.  The residual gas is at its dew point when it leaves the cold separator and is then delivered to the transmission pipeline. 
 
The PSM/RMP-regulated substances handled at this facility are LPG, drip gas, and propane.  Following is a breakdown of the locations of these materials at Roundup: 
 
NGL Plant Propane System:  Maximum Volume = 500 gallons       Maximum Weight = 2530 lbs. 
Propane Makeup Tank:          Maximum Volume = 800 gallons       Maximum Weight = 4048 lbs. 
LPG Product System:            Maximum Volume = 150 gallons       Maximum Weight = 759 lbs. 
LPG Product Storage:           Maximum Volume = 9600 gallons     Maximum Weight = 48,576 lbs. 
Drip Gas:                               Maximum Volume = 5000 gallons     Maximum Weight = 25,300 lbs. 
 
The propane and liquid hydrocarbon system is the only covered process at this time at the Roundup Gas Storage Facility.  T 
he balance of the plant is regulated under DOT Pipeline Safety regulations Parts 190-199. 
 
Filling of the tanks is administratively limited to 80% of the tank capacity by NFPA 58 requirements, as corrected for facility elevation. 
 
Release Scenarios 
Worst-case and alternative release scenarios have been determined after careful review of the regulation and consideration of the storage vessel configuration at the facility.  For worst-case release scenario, the regulation is clear.  The assumption is that the single largest container of a regulated substance (the LPG product storage gas tank or 48,576 pounds of LPG) is released over a ten-minute period.  No active mitigation may be considered.  Worst-case meteorological conditions are also assumed to be present.  Reference Table 9 of the RMP Offsite Consequence Analysis (OCA) Guidance (dated May 24, 1996) was used to determine the distance to overpressure of 1.0 psi for a vapor cloud explosion of hydrocarbon product.  A distance of 0.30 m 
iles to the flammable endpoint was determined for a release of 48,576 pounds in ten minutes.  The RMP*Comp model also predicted the same distance to the flammable endpoint. 
 
The alternative release scenario was developed based on discussions at the process hazard analysis and consists of a release of 2777 pounds of LPG from the LPG product storage tank over a one-hour period due to continued release (and potential failure open) from a 5/16 inch relief valve on the tank.  No active mitigation devices were considered to influence the release scenario.  The ALOHA air dispersion model was used to determine the volume of LPG that would be released in sixty minutes, and Reference Table 9 of the RMP OCA Guidance was used to calculate the distance to overpressure of 1.0 psi.  A distance of 0.05 miles to the flammable endpoint was determined. 
 
Prevention Steps for LPG, Drip Gas, and Propane 
The prevention program and chemical-specific prevention steps are described in detail in the Roundup PSM/ 
RMP manual.  The prevention program includes the Program 3 elements: 
7 Employee participation, which includes provisions for active participation by plant employees in the development and implementation of the facility PSM/RMP program, as well as ready access to program information 
7 Process safety information, which has been collected in the facility office and is summarized in the PSM/RMP manual 
7 Process hazard analyses (PHAs) - The initial PHA for the LPG, drip gas, and propane system was conducted in May 1994;  the PHA was updated in June 1995.  A subsequent PHA was conducted in March 1999.  All recommendations from the PHA have been, or are being, addressed. 
7 Operating procedures for the facility operations, which are included in the Job Books located at Roundup 
7 Training for all plant personnel involved in the operation and maintenance of the plant operations 
7 Contractor management policy, which is to not allow contractors to operate or maintain the RMP-regulated processes 
7  
Pre-startup safety review procedure for implementation for significant system changes to ensure that the construction and equipment installation is according to design specifications, appropriate procedures are in place and accurate, a PHA has been done and the recommendations resolved, and employees are trained prior to startup of the modified system 
7 Mechanical integrity program through the operator computer system to ensure that the system equipment is maintained in good and safe working condition.  Facility personnel conduct daily visual inspections of the system.  The date and equipment included in 7.7 b and c address the last major PM activity. 
7 Hot work procedures to require controls as specified in the Gas Standards Manual before hot work is performed on the LPG, drip gas, and propane system 
7 Management of change program to ensure that proposed system changes are comprehensively evaluated before implementing the change 
7 Incident investigation procedures for the investigatio 
n of any catastrophic (or potentially catastrophic) incident associated with the LPG, drip gas, and propane system 
7 Compliance audits to be conducted at least once every three years to ensure the continued compliance of the Roundup PSM/RMP program.  A PSM/RMP audit was conducted in February 1999. 
 
Accident History 
Within the five-year period prior to the submittal of this RMP, there were no accidental releases of regulated flammable materials meeting the requirements of 40 CFR 68.42. 
 
Emergency Response Program 
This facility has established and maintains an emergency response program that is coordinated with local response agencies.  The program is described in detail in the Emergency Planning and Response section of the PSM/RMP compliance manual and meets the requirement of 40 CFR 68.95.  The goals of the program are to protect onsite employees from the hazardous effects of chemical releases and to minimize the effects of releases on the general public.  The program is routinely revi 
ewed and updated to reflect personnel and regulatory changes. 
 
Planned Changes for Improved Safety 
Ideas for changes to improve safety are actively sought from employees.  Employee safety meetings that focus on chemical safety issues are held regularly at this facility.  Employees are encouraged and trained to recognize hazards and present ideas to eliminate them or to minimize the potential consequences of those hazards. 
 
During the development of the Roundup PSM/RMP program, process hazard analyses were conducted with key employees to meet the prevention program requirements.  During these sessions, recommendations were made for the purpose of improving safety and preventing accidental chemical releases.  Each recommendation has been or will be considered for implementation.  Though not all recommendations may be implemented, all will be considered.  The exercise has provided all affected employees with a heightened awareness of safety issues related to the covered processes.
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