Most reserve pits, built on the oilfield, are divided not by their specific use for processing but rather they length of time they’ll hold the same wastewater. Temporary pits are obviously held to less strenuous standards than pits designed to permanently hold the hazardous waste from the drilling operation. However, in some areas they’re the only pits allowed, even with careful lining and extra deep excavation. It may be possible that temporary, shallow, surface pits are the only types of reserve pits allowed on a new oilfield or in the expansion of an existing operation. Before deciding how many temporary and permanent reserve pits you’ll need, consider the following facts.
State and Local Laws
Unlike other types of hazardous wastewater, oil drilling residues are not regulated by the EPA or its usual regulations over the waters of the US. This is specifically stated in the Resource Conservation and Recovery Act that gives the EPA jurisdiction over most other types of waste products. Instead, these kinds of hazardous materials are regulated at the state and local level instead. This means that every area has different rules on how pits can be built and what’s required to keep them secure. Some areas may mandate a double liner system for even the smallest pits, holding mildly contaminated waste, while others may allow basically any kind of open pit you want to build. The biggest difference in laws usually is determined by whether the pit is permanent or temporary. Permanent storage pits are often banned in many areas, even if they were allowed in the past. In these areas, all pits must be emptied of waste eventually and sealed up with no hazardous materials left in them. Other regions allow for the opposite, and encourage oilfield owners to dig deep pits they can simply cap at the end of the project. Find out what your local laws support before assuming either type of pit will be a better fit for your oilfield.
Deep Bury Pits
When permanent disposal is desired on-site, right from the start, deep bury pits are the usual recommendation. These permanent pits are designed to be capped with up to 12 solid feet of dirt to ensure that no hazardous materials can reach the surface for centuries to come. This means that they’re generally dug 20 feet deep, or even deeper, to leave plenty of room for both the wastewater and sludge in the pit. Even with a large surface area and volume, this tends to lead to a deep and narrow pit that is hard to properly line. Make sure you’re using a reinforced liner material that can handle being stretched and anchored to the ground to line any permanent storage pits that will be capped in the end.
Temporary reserve pits may be able to be lined with a less durable liner than a permanent design, since they’re only going to hold waste for a specific time frame. However, this can backfire when you consider that the temporary storage pit will be filled over and over again. While it won’t have to contain the waste forever, it will experience more wear and tear over time due to the process of filling and emptying out the abrasive sludge materials. Durable liners are required for both types of reserve pits, and you should use a liner that’s rated to last decades for all of them.
Costs of Transport
With the need for extra durable liners and leak detection systems, it’s easy to assume that permanent, deep bury pits will be more expensive than dealing with temporary pits. Yet, this depends on many factors, including but not limited to:
- The availability of local waste processing or storage facilities capable of receiving potentially radioactive solid waste
- Storage for mixed wastewater if there’s no option for processing the liquid and solid wastes separately
- Expenses related to dredging up and hauling the heavy, hazardous waste to the nearest storage facility.
Between these extra costs for temporary storage, you may find it’s less expensive than you think just to build permanent storage pits. Of course, this depends mostly on what’s allowed by local environmental protection laws. If you’re still allowed to build new, deep bury pits for oilfield waste in your area, weigh the savings of being able to avoid transporting the waste and keeping it on site from beginning to end.
Don’t get confused by the differences in temporary and permanent reserve pits for oilfield wastewater. Both types of pits need similar levels of liner quality and careful attention to detail during construction. Before assuming you’re free to set up deep bury pits as long as you have the right liners, check in with local and state environmental protection agencies. We’ll help you find a liner that meets even the most stringent regulations for storage pits in oilfields from our selection here at BTL Liners.