Washington Gas Ravensworth Station

Excerpted from Virginia Places Natural Gas Storage in Virginia:

In 1962, Washington Gas excavated an underground cavern in Fairfax County to store 13 million gallons of Liquefied Petroleum Gas (LPG). The Ravensworth Station reservoir was carved out of the nearly 500-million year old Occoquan granite bedrock west of Lake Accotink Park. The cavern was constructed first by drilling a 42-inch wide hole down 400 feet, then lowering one man to the bottom to start the excavation. The underground hole was gradually widened enough for pieces of equipment less than 42-inchs wide to be lowered down through the pipe. The cavern has a 25-foot high ceiling, with pillars of granite left at different spots to support the roof.

The Southern Railway delivered over 400 tanker cars to a siding near Springfield for the initial filling of the cavern. There is little indication of the natural gas storage facility on the surface, other than the compressors which mix air into the propane to create a mixture with the appropriate burning characteristics.

A geologist who managed the site noted that during excavation, workers wore raincoats due to water leaking into the cavern. That provided a clear indication that the bedrock was fractured, but the walls were not sealed with cement of any kind. To keep the propane (compressed into its liquid state) in the cavern, Washington Gas relies upon a water cap to maintain geostatic pressure.

Water that leaks into the cavern is constantly extracted and injected into the soil, and the company ensures the soil stays saturated even in a drought. Propane does not dissolve easily in water so nearly all of the Liquefied Petroleum Gas stays trapped in the cavern. Traces of propane have been identified in the soil after a nearby resident notices the smell of "swamp gas" in an area without a swamp, and tiny bubbles may escape into Accotink Creek. Most likely, that propane was brought to the surface with water pumped out of the cavern, and there is not a series of cracks in the granite stretching 400 feet up to the surface.

And here is a newspaper clipping:

Gas Company Prepares Virginia Storage Plant for Cold Winter Weather:
Winter had finally breezed onto the Virginia scene and nobody knows it better than the men who work at Washington Gas Light Company's Ravensworth plant in the Springfield area. Just ahead of the first icy blast of cold winter weather, the gas company's Ravensworth plant starts tuning up for its winter work. Engines are tested, pumps are started, valves are turned, and gauges are checked as the men who operate the plant prepare for winter. The Ravensworth plant, with its huge man-made underground cavern holding 13 million gallons of liquid propane, is undergoing its first winter at full capacity. The exact location of the Ravensworth station is near the center of a 42-acre trace bounded on the south by the Southern Railroad, on the west by Rolling Road, on the east by other property owned by Washington Gas Light Company, and on the north by the old right-of-way of the Southern Railroad. The cavern, which holds 13 million gallons of propane, was mined out of solid bed rock more than 400 feet below the surface. It took more than two years of mining and construction to complete this plant.