AK0038661 – Hilcorp Alaska LLC., Endicott Operations, Notice of Review

Notice Of Review Of An Alaska Pollutant Discharge Elimination System (Apdes)Preliminary Draft Individual PermitTo Discharge To Waters Of The United StatesDEC has prepared an APDES Preliminary Draft Individual Permit, AK0038661 – Hilcorp Alaska, LLC, Endicott Operations (Permit). The Preliminary Draft Permit, Fact Sheet, and associated documents are available to the applicant for a 10-day review. Following the close of the 10-day applicant review period, DEC will prepare a Draft Permit and Fact Sheet for a formal 30-day public review period. Public comments will be accepted during the formal 30-day review period. You can access the documents on the DEC Wastewater Discharge Authorization Program webpage at: https://alaska.gov/dec/water/wastewater/.DEC Contact: Amy WockenfussAlaska Department of Environmental ConservationDivision of Water - Wastewater Discharge Authorization Program555 Cordova St., 3rd FloorAnchorage, AK 99501-2617 (907) 269-8874amy.wockenfuss@alaska.govPreliminary Draft Permit Review Period: Start Date: October 6, 2025 End Date: October 20, 2025, at 12:00 pm (midnight) Alaska Daylight TimePermit No.: AK0038661Permittee: Hilcorp Alaska LLCEndicott OperationsDuck Island, Stefansson Sound, Beaufort Sea3900 Centerpoint Drive, Suite 1400Anchorage, AK 99503Proposed Permit Coverage: The proposed permit covers the discharge for Endicott Operations located on Duck Island in Stefansson Sound, Beaufort Sea, Alaska. The facility produces waterflood at a seawater treatment plant (STP) and distributes the waterflood for injection into oil producing formations to maintain formation pressures that enhances oil recovery. The authorized discharges include: Outfall 001A – Combined Outfalls 002A and 002B Outfall 002A - STP and Potable Water (POW) Treatment Backwash Outfall 002B - Domestic Wastewater Outfall 003A - Continuous Flush SystemThe combined discharge of the STP/POW (Outfall 002A) and Domestic Wastewater (Outfall 002B) through Outfall 001A includes the authorization of a chronic mixing zone for temperature, total residual chlorine (TRC), pH, and chronic whole effluent toxicity, as well as an acute mixing zone for TRC. There is no mixing zone authorized for Outfall 003A.Deadline for Written Applicant Review Comments: The deadline for preliminary draft permit review comments by the applicant is October 20, 2025 12:00 pm (midnight) Alaska Daylight Time.Administrative Record:The APDES Preliminary Draft Permit, Fact Sheet, and associated documents are available for public review at the DEC offices located in Anchorage, Fairbanks, Juneau, Wasilla, and Soldotna. Please contact the office of your choice to arrange for hard copies of the documents to be available for your review. 555 Cordova Street Anchorage, AK 99501 907-269-6285 610 University Avenue Fairbanks, AK 99709 907-451-2100 If you would like further information or to see any additional supporting technical documents, contact the DEC Contact/permit writer at the address shown on page 1. The permit documents can be accessed from the DEC Wastewater Discharge Authorization Program website at https://dec.alaska.gov/water/wastewater/. To receive email notifications about the APDES Program, including when permits are available to review, follow the link to join the APDES email list https://list.state.ak.us/mailman/listinfo/DEC-APDES/ .Disability Reasonable Accommodation NoticeThe State of Alaska, Department of Environmental Conservation, complies with Title II of the Americans with Disabilities Act (ADA) of 1990. If you are a person with a disability who may need special accommodation in order to participate in this public process, please contact ADA Coordinator Kristin Mabry, kristin.mabry@alaska.gov, 1-907-334-0884; or TDD Relay Service 1-800-770-8973/TTY or dial 711 at least 3 days prior to the expiration/closure date of this public notice to ensure that any necessary accommodations can be provided