Compressor Station 84

As part of the Hillabee project, Williams is proposing to construct a new 32,000-horsepower compressor facility along its Transco pipeline in Choctaw County, Ala.

What is a Compressor Station?

DSC03936Compressor stations, sometimes called pumping stations, are the “engine” that powers an interstate natural gas pipeline. As the name implies, the compressor station compresses the natural gas, (increasing its pressure) to push the gas through the pipeline.

Most compressor stations are automated so that the compressors can be started, controlled and stopped from a central control location regardless of the weather conditions, time of day, or day of the week. The automation system also acts to protect the equipment, facility, and surrounding area in the event that the equipment is not operating as it was intended. The operators of the system continuously monitor and adjust the mix of compressors that are running to maximize efficiency as well as keeping detailed operating data on each compressor station. The control center also can remotely operate shut-off valves along the pipeline system.

Facility Location

Williams’ preferred location for the Choctaw County compressor facility is within the boundaries of around 40 acres of properties that are being purchased by Williams. The proposed site will include the use of less than 10 acres for the final compressor station. This location was chosen to:

  • Create the largest possible buffer between the facility and property boundaries.
  • Minimize the impact to the property – location was previously cleared of timber.
  • Provide access to existing mainlines, Brightwater Road and utilities.

This location meets the requirements necessary for siting a natural gas pipeline compressor station. Some of the factors that were considered include physical constraints such as proximity to the existing pipeline, access to electric power, pipeline hydraulics, compatibility with local zoning, land use and land development, site terrain, water table and storm water management, and site accessibility. Williams also evaluated a number of environmental factors, including potential impacts to nearby residences. This includes a detailed analysis of the project’s effect on wildlife, vegetation, wetlands, water bodies and groundwater, geology, soils, land use, air and noise quality.

Facility Design

  • Two 16,000-horsepower gas turbine-driven compression units
  • One emergency generator
  • Two electric air compressors and an air storage tank
  • A pre-engineered metal building will serve as a warehouse/workshop with roll-up doors for storing spare parts and equipment
  • Two above-ground storage tanks for waste oil and oily water
  • A security fence enclosing all equipment

The gas turbines and the attached compressors will be installed within a metal building to both limit noise from the gas turbines and the compressors and to provide protection from the elements. Any above-ground piping will also be insulated to minimize noise.


A number of environmental surveys (threatened and endangered species surveys, wetlands surveys and archeological site surveys) have already been conducted to identify any potential environmental impacts. No significant impacts have been identified. A soil erosion plan will be in place to minimize erosion impacts during construction.


As part of the design process, an independent acoustical consultant will be engaged to conduct a sound study to assess the impact to nearby Noise Sensitive Areas (NSAs) , which are defined as residences, schools or hospitals. The design for this facility will be based on certificate conditions expected to be set forth by the Federal Energy Regulatory Commission (FERC). The current FERC policies limit the noise attributable to the new facility to a day-night average of 55 dBA at nearby NSAs. This is the approximate equivalent sound of rainfall, or a normal conversation between two people.

Safety & Security

The station will be equipped with federally-required and industry-recognized safety features such as pressure relief valves, emergency shutdown systems, and gas detection devices. The facility is planned to be staffed by onsite personnel during normal business hours. Outside normal business hours, the station will be fully automated for remote operation and monitored 24/7 by Williams’ operations center in Houston.