Dougan Compressor Station - Executive Summary
Executive Summary |
HS Gathering's Dougan Compressor Station is not covered under OSHA's PSM Standard because it is a normally unoccupied remote facility. However HS Gathering has elected to use OSHA's PSM Standard as a model of good business practice at this compressor station even if it is "normally unoccupied remote facilities".
Accidental Release Prevention and Response
HS Gathering LLC has a long-standing commitment to worker and public safety. This commitment is demonstrated by the resources invested in accident prevention, such as training personnel and considering safety in the design, installation, operation, and maintenance of our processes. Our policy is to implement reasonable controls to prevent foreseeable releases of regulated substances. However, if a release does occur, HS Gathering personnel are trained on how to respond to such emergencies. If the situation requires, HS Gathering will notify, cooperate with, and support the various emergency response agencies.
Location and Regulated Substances
HS Gathering's Dougan Compressor Station is located in Weld County, Colorado about three and one quarter (3 3) miles east of old Highway 85 (Road 27) on WCR 10 in a rural area which is used primarily for farming.
The Dougan Compressor Station consists of one compressor unit, #21, that discharge 30 MMCF/D through glycol dehydration to delivery points via 16" and 20" cleanable pipelines. The discharge pressure is not to exceed 1220 psig. The station is equipped with inlet seperation. Liquids separation (condensate) goes to four 225 barrel storage tanks.
The purpose of a compressor station is to increase the pressure of the gas being transported in the pipelines and to reduce the dew point of the gas to a level that is acceptable for pipeline transmission. Each compressor station receives gas from various gathering lines and supplies the pipeline(s) that transports the gas to a processing plant. Control of the dew point is critical since the
incoming gas contains moisture (water and heavy hydrocarbons). The amount of moisture in the gas varies from day to day depending on a great number of variables at the well heads. The dew point increases as the concentration of moisture in the inlet gas increases.
As gas flows through the pipeline, its temperature will decrease to about the same temperature as the surrounding environment. If this temperature 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 gas flow, particularly at orifices and bends in the pipe. In extreme cold, the hydrates may form a potentially dangerous ice plug.
In order to reduce the dew point of the gas (minimize the formation of hydrates), the inlet gas is put through a slug catcher, an inlet separator, and a glycol contactor with scrubber to remove moisture. Compression of the gas causes some of the naturally occurring hydrocarbons, which are in the vapor
phase of the inlet gas stream, to condense out of the stream. This allows heavy hydrocarbons and water to condense out of the gas resulting in a lower dew point. These condensed raw natural gas liquids (NGL), also called condensate, are stored in tanks until there is a sufficient volume to be pumped into a tank truck for transportation for processing into marketable products. The glycol is regenerated and used again.
The flammability and volume of the raw NGL stored at The Dougan Compressor Station triggered coverage under the EPA RMP Standard.
History and Ownership
The Dougan Compressor Station was built by Panhandle Eastern Co in the early 1980's. HS Resources entered into a purchase and sale agreement with Kinder Morgan Inc., formerly known as KN Energy, in December of 1999. KN Energy operated the system from April 1993 through December 1, 1999.
HS Gathering has determined that Program Level 1 applies to the Dougan Compressor Station since it has a documente
d Emergency Response Plan which has been coordinated with the local Fire Department and has had no accidental release of the regulated substance (condensate) that directly or indirectly caused a death, injury, or response or restoration activity for an environmental receptor in the previous five years. Also, the facility's distance to a "public receptor" is greater than the distance to the calculated endpoint for the worst-case scenario of 0.1 miles.
Offsite consequence Analysis Results
The worst-case scenario (WCS) associated with flammable substances in a Program Level 1 process at the Dougan Compressor Station is a vapor cloud explosion resulting from a catastrophic tank failure in the condensate tank storage area. A written procedure is in place to limit the storage inventory to 80% of the maximum tank capacity. Therefore the reduced inventory is assumed, resulting in a release of 31,000 lbs. (approximately 5700 gals.) of condensate over a 10-minute period. Although we have va
rious controls to prevent such releases and to manage their consequences, no credit for passive mitigation measures (such as dikes or berms) was taken into account in evaluating this scenario. The maximum distance to the 1-psi overpressure from a vapor cloud explosion of this material was 0.1 miles. No Program Level 2 or 3 processes containing regulated flammable substances were identified at the Dougan Compressor Station.
Emergency Response Program
The Dougan Compressor Station has established and maintains an emergency response plan that is coordinated with local response agencies. The goals of the program are to protect employees and the general public from the hazardous effects of releases and to minimize the effects of any releases. The program is routinely reviewed and updated to reflect station, personnel, and regulatory changes.
During the last five years, there have been no accidents that meet the criterion for inclusion in this submittal
ges 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. Employees are encouraged and trained to recognize hazards and present ideas to eliminate them or to minimize the potential consequences of those hazards.