Surface spills are one of the biggest environmental hazards associated with oil and gas production. Luckily, operators are getting better at preventing spills and regulations are more stringent – the total volume of oil spilled between 1998 and 2007 was 77% lower than the oil spilled between 1969-1977.
However, despite the best efforts of operators and regulators to prevent spills preemptively through precautionary procedures and the installation of spill-containment systems, spills do happen. Given the wide range of chemicals used in drilling, stimulation, and enhanced recovery, the appropriate response to a surface spill will vary.
The first line of defense against spills is to catch them as soon as they happen in a prepared containment system. Although tanks are made to be durable and sturdy, there are incidents that can cause them to leak or rupture. Because of this risk, most states have regulations and good operators employ best practices that ensure that the entire volume of a leaking tank can be contained by a lined berm or containment wall.
But sometimes even these precautions fail.
Interestingly, most spills are not caused by human error. Instead, they are due to equipment failure – leaking tanks and pipes, failed containment systems, and faulty pit liners.
The first priority of a spill response, after ensuring everyone’s safety, is to find and contain the source of the spill. This could be as easy as closing a valve or patching a tank, or as time consuming as digging up a pipeline or installing replacement equipment. Drains and other paths for rapid fluid migration into the groundwater should be closed off with valves or blocked by mats.
After the spill is under control, operators should immediately get in communication with the local authorities and mobilize spill response resources.
Containing and collecting the spilled material should be the highest priority. The longer the material is on the land surface, the more oil will be absorbed into the ground or enter surface waters.
If the material is lighter than water (and most spilled materials are), water can actually be added to the spilled material. The water will sink to the bottom and may help reduce the total amount of contaminant absorbed.
Pumps are usually used to collect the spilled liquid, which is stored in a tank for treatment and disposal. Once the spilled liquid has been pumped, the soil itself may need to be dug up for treatment.
Images: “Surface Spills” by Michael Black; “Containment Berms” by Michael Black; “Overhead Containment” by Michael Black