The well pad
The average well pad is a cleared, graded and gravelled are of approximately four to seven acres on which the drilling and hydraulic fracturing operation takes place. The well pad has developed from supporting a single well to becoming a multiple well operation, and being able to support up to 12 natural gas wells. Concentrating the ecological footprint of a larger number of wells and their associated pipelines, roads and infrastructures in one single pad, greatly reduces the environmental impacts of drilling. While there has been a definitive increase in multi-well pads the majority of pads today are still single pads. The average pad to well ratio in Pennsylvania Marcellus wells in 2010 was 2.15 with an increasing tendency.
A typical well pad houses the well itself, water storage facilities and space for the mobile blender facility, sand storage units, pump trucks, chemical trucks and staff infrastructures. The well head is connected to the casing in the ground which, once fracturing is completed, directs the gas to the different surface facilities. From the well head the gas is initially directed into a sand trap and separator which separates sand and water away from the gas. Once separated the produced water is pumped into wastewater tanks on the well pad where it is stored until it is hauled off and disposed.
Access roads to well pads, often built on private land, have to be constructed. Often, smaller public roads have to be upgraded to support the high volume of truck traffic required for an operation. Sharp increases in traffic occur during the initial drilling and hydraulic fracturing stages, but decrease again once the fracturing process is completed.
Water storage sites
Due to the large volume of freshwater required to hydraulically fracture a well freshwater is often stored near wells in lined impoundments, thus avoiding the need to extract water during low flow periods. Such impoundments can be constructed from compacted earth from the impoundment site and then compressed to form embankments. Impoundments can hold several million gallons with surface acreage of up to five acres. Pipelines can be used to connect the impoundment with the well site.
Water withdrawal sites
The large volumes of water required for the drilling and hydraulic fracturing operations have to be obtained under license from permitted water withdrawal sites. These are usually cleared areas near waterbodies and can experience sharp periodic increases in truck traffic4.
Equipment storage sites
Natural gas drilling companies operating in an area require storage facilities for their vehicles and considerable amount of drilling equipment. Old repurposed well pads are commonly used for this purpose4.
Campgrounds for workers
As many of the workers employed by drilling companies are temporary or move from well to well with drilling activities accommodation in rural areas is required. In Pennsylvania and elsewhere workers are being housed in temporary housings such as caravan parks and campgrounds4.