In an article in Sunday’s PI, Bob Arrington* commented on the recent WPX Energy wastewater spill south of Silt.
BATTLEMENT MESA — A retired engineer who serves on the Garfield County Energy Advisory Board, and who has been a critic of the regional energy industry, told the Post Independent on Friday that he feels a recent spill of a large volume of “produced water” at facilities owned by WPX Energy is more of a problem for the company than WPX has admitted …
… But according to retired engineer Bob Arrington, the company should have tested the equipment involved when it purchased the pipelines and other infrastructure from Orion.
“If they accept somebody else’s design,” Arrington wrote in an email to the Post Independent, “they assume the responsibility” for the integrity of the system.
“Just getting it and using it without verifying integrity is negligence in itself,” Arrington continued. “WPX is supposed to have engineers that have the know-how and ability to determine the proper use [of equipment] and problems that can arise.”
Arrington’s email to the Post Independent contained a lengthy, and highly technical description of how he feels the company may have erred in its use of the Kokopelli Field equipment.
Attempts to obtain comments from either Alvillar or the COGCC on July 26 also were not successful, nor were efforts to contact Kirby Wynn, Garfield County’s oil and gas liaison, regarding Arrington’s concerns.
The story, as reported, had a less pressure rated piping arrangement below the valve that failed.
WPX reported to the Colorado Oil and Gas Conservation Commission that the incident happened when water was being transferred between two storage pits. A valve intended to isolate a lower water line section failed, allowing pressure to build up in that section until an above-ground riser with a pressure rating below that of the line ruptured. [excerpt from The Daily Sentinel article]
To use such a system, the valve had to be used not just as isolation, but when flowing it had to function as a pressure reducer. Downstream of the failed valve had to be another valve or tank (dead end or a head pressure maker) for pressure to rise on the weaker pipe. The downstream pipe should have been pressure rated to the upstream pipe or the valve should be closed on fail and even then failed valve seat should be considered.
If this was purchased used equipment, there is every likelihood there were field people assembling it with available material or whatever might be around a supply yard. Before service there should be pressure tests on the system. But with a valve used as this one, it should be at least a normally closed valve. The reason downstream piping should be pressure rated to the feed pipe, is valve seats can fail. If the weaker pipe is on a closed end or pressure causing end, then the design is a “must” to be as high a rating as the feed pipe.
“However, the piping between the more severe conditions, and the valve shall be designed to withstand the operating conditions of the equipment or piping to which it is connected” [American National Standard for Pressure Piping]. Which, if the pressure of the equipment can cause the pressure in the pipe to go to the pressure of the “more severe” feed pipe, then the valves and equipment pipe must be designed for the pressure (from all sources) in the feed pipe. Now if a pressure relief valve of sufficient capacity is put on the line to equipment, then the rating of the relief valve can be the design pressure. This design is to consider pressure and temperature ranges, pipe support, expansions, torques, impacts, earthquake, etc.
A dangerous practice is to put in plastic pipe with a closure valve fed from a metal pipe at much higher pressure than the plastic pipe rating. If the closure valve is operated, the plastic pipe becomes the victim, as commonly seen in irrigation pipes blown apart by attaching to metal head gate piping without pressure reducers and relief valves.
If they accept somebody else’s design, they assume the responsibility if that outfit has not had certification process involved (buyer beware). They can blame the seller, if that seller had certified the integrity by professional certification, and it wasn’t “code”; but, just getting some equipment and using it without verifying integrity is negligence in itself. WPX is supposed to have engineers that have the know-how and ability to determine the proper use and problems that can arise.
*Bob Arrington is a retired engineer and the Battlement Mesa citizen representative on Garfield County’s Energy Advisory Board (EAB). He also represents the Grand Valley Citizens Alliance and the Battlement Concerned Citizens.