Re: Beneficial Re-use of Treated Sanitary Waste to Flush Class II-D Well
Ms. Shannon Donnelly
ConocoPhillips Alaska Inc.
P.O. Box 66
Kenai, AK 99611
Dear Ms. Donnelly:
By letter dated April 19, 2004, ConocoPhillips Alaska (“ConocoPhillips”) requested authorization to beneficially re-use domestic waste and treated sanitary effluent at the Tyonek Platform for flushes of the on-board Class II disposal well A-12. The Tyonek Platform is the sole facility developing the North Cook Inlet Unit gas field. Well A-12 is both a gas production well and a periodic Class II disposal injector, completed with dedicated production and injection tubing strings. ConocoPhillips recently completed well work on the Tyonek Platform to increase gas production. The installation of real time disposal into Well A-12 for the produced water stream generated at the platform was also accomplished. Increased produced water injection into Well A-12 will necessitate periodic flushes to ensure the availability and reliability of this lone disposal well at Tyonek Platform.
Disposal Injection Order (DIO) 17 does not list domestic waste and treated sanitary effluent as eligible for injection into a Class II disposal well. A National Pollutant Discharge Elimination System permit (#AKG285011) issued by EPA authorizes the discharge into Cook Inlet of these waste streams. ConocoPhillips characterizes the proposed beneficial re-use as a solution to the challenges of providing clean (non-corrosive) water for well maintenance and minimizing discharges directly to the Cook Inlet.
Confinement of fluids to the intended injection zone in Well A-12 has been demonstrated by historical injection performance data provided by ConocoPhillips. Well integrity has been demonstrated by successful mechanical integrity testing and monitoring the well’s annular pressures. Periodic flushes using the waste streams outlined by ConocoPhillips will have no detrimental effect on the confinement of fluids or well integrity.
The periodic flushing of an injection well is a well maintenance practice that is integral to the operations and necessary for injection well reliability. Exploration and production wastes associated with oil and gas development are exempt from the requirements of Section 3001(b)(2) of the Resource Conservation and Recovery Act (RCRA). The exemption provides for mixing a non-hazardous waste with an exempt waste; the resulting commingled stream is considered exempt. Mixing of produced water (exempt) with commingled domestic waste and treated sanitary effluent (non-exempt) streams will occur in the well during the flush procedure. The Commission believes ConocoPhillips’ proposed action to use treated sanitary effluent (non-hazardous, non-exempt) to periodically flush Class II-D Well A-12 is consistent with the provisions of the RCRA exemption.
Therefore, the beneficial reuse of domestic waste and treated sanitary effluent as make-up water for routine and necessary flushes in North Cook Inlet Unit Well A-12 is approved by the Commission.
DONE at Anchorage, Alaska and dated May 3, 2004.
The Alaska Oil and Gas Conservation Commission
John K. Norman, Chair
Daniel T. Seamount, Jr.
BY ORDER OF THE COMMISSION