Weld County: A Leader in Oil & Gas Production

Weld County leads the state in oil and gas drilling activities and production. With more than 22,000 active wells, the county is responsible for about 90% of all crude oil production in Colorado and is on pace to becoming number one in gas production. In spite of the recent market downturn, production in Weld County exceeded 100 million barrels of oil in 2015.

As part of the exploration and production process, liquid and solid wastes are generated, some of which have been designated by the Colorado Department of Public Health and Environment (CDPHE) as potentially containing TENORM. In 2015, over 34 million barrels of produced water were generated. Much of the produced water is injected into disposal wells. There are over 40 disposal wells currently active in Weld County.

There are no commercial landfills in Colorado solely designated for disposal of exploration and production wastes. Because waste volumes from oil and gas exploration activities in Weld County far exceed all other Colorado counties, Pawnee Waste’s location will benefit the energy community by providing a convenient location.

The Colorado Solid Waste Act prohibits disposal of radioactive materials and materials contaminated by radioactive substances at landfills unless a landfill is specifically designated for that purpose. According to a CDPHE letter dated November 7, 2017, “E&P waste streams with the potential for high concentrations of TENORM are prohibited from disposal in all landfills in Colorado not specifically approved and designated to take them unless and until each waste is sampled and tested on a per shipment basis or in a representative and statistically-valid manner.” Pawnee Waste is the only landfill identified in Weld County as approved for the receipt of TENORM wastes, including horizontal cuttings. For more information on this letter, please click HERE.

For more information on oil and gas facilities in Weld County, please visit the Colorado Oil & Gas Conservation Commission website.


Protecting Public Welfare

The oil and gas industry is heavily regulated by federal, state and local government entities in order to help protect our health, safety and public welfare.

In Colorado, the Oil & Gas Conservation Commission (COGCC) regulates E&P disposal wells and certain land application facilities, and the Department of Public Health & Environment (CDPHE) regulates the design and operation of commercial E&P solid waste sites. Both agencies are tasked with the protection of our air, water and land.

Weld County requires all commercial waste disposal facilities to obtain a Use by Special Review (USR) permit. The USR approval process involves review by Weld County’s Departments of Planning, Public Works and Public Health and Environment.

The departmental reviews are followed by public hearings before the Weld County Planning Commission and Board of County Commissioners. This review and approval process helps ensure that community concerns are thoroughly addressed prior to a final determination by the Board of County Commissioners.

In September 2016, public hearings were held, and approval was granted by the County Commissioners for the development and operation of the Pawnee Waste facility. At this time, it is the only landfill in Weld County that has been technically reviewed and recommended by the state and designated by the county for receipt of TENORM.


Radioactivity and BTEX in E&P Wastes

Pawnee Waste recently retained Gradient to compile and review information on the levels of radioactivity and benzene, toluene, ethylbenzene, and total xylenes (BTEX) concentrations found in exploration and production (E&P) wastes from oil and gas from shale formations in Colorado and other states. Their review included data from vertical, transitional, and horizontal component of wells complete in shale formations. As part of their research, Gradient reviewed publically available reports from government agencies and trade associations, government databases, operator assays, and peer-reviewed literature for relevant information. Although the amount of data for E&P waste streams are limited, they cover multiple basins in Europe and the US, thereby providing a basis for comparing levels of radioactivity and BTEX from different areas.

Gradient found that E&P wastes have detectable levels of radioactivity and BTEX and that data from Colorado are in the range of concentrations found in other areas of oil-and-gas-shale development. The data from Colorado also indicate that multiple types of E&P wastes can have levels of radioactivity and BTEX that exceed Colorado Department of Public Health and Environment (CDPHE) administrative levels and the Colorado Oil and Gas Conservation Commission’s (COGCC) standards, respectively.

In their report, Gradient adionuclide data for various wastes, including drill cuttings, proppant, drilling mud, sludge, flowback solids, pipe and tank scale, filter cake, sludge, and other solid wastes associated with E&P activities. They grouped these wastes into the following categories for discussion purposes due to similarities in their levels of radioactivity and the character of the waste: (1) drill cuttings, proppant, and drilling mud; (2) pipe and tank scale; and (3) filtration wastes, sludge, and sump solids. Samples from each of these waste materials had detectable levels of radioactivity.

A large portion of the compiled data was for drill cuttings. While both vertical and horizontal drill cuttings have the potential to exceed CDPHE administrative levels, cuttings from horizontal sections of the borehole tend to have higher radioactivity, and hence a higher likelihood of exceeding CDPHE administrative levels. They identified measured levels of radioactivity in drill cuttings from Colorado, New York, Pennsylvania, West Virginia, and Poland. The concentrations of radioactivity found in the cuttings from these different areas were generally consistent, suggesting that the radioactivity of oil- and gas-shale formation cuttings can be expected to vary within the same general range. The activities of natural thorium and uranium in cuttings from Colorado were also within the ranges of those found in other areas of oil- and gas-shale development.

The oil and gas industry has known for decades that pipe and tank scale (“scale”) can accumulate high levels of radioactivity, mainly due to radium. High radioactivity in scale results from radium associating with other alkaline earth metals (e.g., calcium, barium, strontium) in sulfate- and carbonate-based mineral deposits that precipitate from production fluids onto pipe and tank walls. Soils impacted by scale cleaning operations may also exhibit elevated radioactivity. Thus, there is a high likelihood that pipe and tank scale, as well as soil impacted by scale cleaning operations, would exceed CDPHE administrative levels for radioactivity.

Filtration wastes, sludge, and sump solids have varying levels of radioactivity, with some of the higher observed values falling between drill cuttings and scale. This result is not surprising, considering that the solids from filtration or settling will be derived from the formation (e.g., containing cuttings, proppant, or mud), but are also subject to formation fluids that allow for mineral precipitates to accumulate, similar to the process that creates pipe and tank scale. Thus, based on the data, and the possibility of precipitate accumulation, we expect filtration wastes and sump solids to have a high likelihood of exceeding CDPHE administrative levels for radioactivity.

BTEX data were compiled for the same E&P waste streams as radioactivity, with the exception of scale. Oil and gas source rocks targeted for production contain BTEX, which is a natural component of crude oil and natural gas. Using BTEX data for crude oil produced from shales in North Dakota and Texas (which have similar BTEX levels compared to other crude oils from the US and abroad), a rock with 1% porosity filled with crude oil or a waste material composed of 1% crude oil would exceed the COGCC standard for benzene by a factor of approximately 86-212. The available data for drill cuttings and a variety of other E&P wastes indicate that these materials are likely to exceed the COGCC standards for BTEX.

Click HERE for the full report, references and data tables.