NOTICE OF CLEAN WATER BRANCH RECOMMENDATIONS FOR
WATER POLLUTION CONTROL PERMIT FOR
SAND ISLAND WASTEWATER TREATMENT PLANT
NPDES PERMIT NO. HI 0020117

The State of Hawaii, Department of Health (DOH), Clean Water Branch (CWB) tentatively recommends to the Director of Health (Director) to renew a National Pollutant Discharge Elimination System (NPDES) permit to regulate and impose water pollution control requirements on treated wastewater discharges to receiving State waters, subject to special conditions, to:

CITY AND COUNTY OF HONOLULU
DEPARTMENT OF ENVIRONMENTAL SERVICES (Permittee)

A permit for such discharge would expire five (5) years from the effective date of the permit.
The Permittee owns and operates the Sand Island Wastewater Treatment Plant (Facility) located at 1350 Sand Island Parkway, Honolulu, Island of Oahu, Hawaii. The Facility has an average design flow of 90 million gallons per day and provides primary treatment of wastewater largely from residential sources in metropolitan Honolulu and eastward to, but not including Hawaii Kai.
Influent from force mains enters the Facility through the influent receiving area and is directed into a wet well located at the headworks. From the headworks, the flow is routed to aerated screening channels which provides preliminary treatment via initial screening, flow measurement, and grit removal. The wastewater is then conveyed to the primary treatment system where it is injected with ferric chloride and anionic polymer to support the treatment process prior to entering primary clarifiers.
After primary treatment, the wastewater is directed to covered ultraviolet light disinfection channels equipped with mechanical effluent bar screens. Following disinfection, treated wastewater is conveyed to an effluent pump station prior to discharge to Mamala Bay through Outfall Serial No. 001, a deep ocean outfall located at Latitude 21°16’48.5″ N and Longitude 157°54’30.4″ W.
Sludge processing, which initially starts with gravity thickeners, occurs at the Facility after the spiral de-gritter and primary clarifier systems within the liquid process stream. The thickened sludge is stored in wet sludge storage tanks and then directed to anaerobic digesters, followed by more sludge storage tanks, and centrifuges for dewatering. The resulting biosolids are processed onsite using a biosolids dryer, which is operated by an independent contractor. Gravity thickener overflow is discharged to the Return Flow Pump Station (RFPS) and the concentrate is discharged either to the RFPS or Solids Return Lift Station (SRLS). The RFPS and SRLS then pump the overflow and concentrate wastewater back to the headworks for treatment.
The receiving waters, the Mamala Bay, is classified by the DOH as Class A, Marine, Wet Open Coastal Waters under Hawaii Administrative Rules (HAR), Section 11-54-6. It is the objective of Class A waters that their use for recreational purposes and aesthetic enjoyment be protected. Any other use shall be permitted as long as it is compatible with the protection and propagation of fish, shellfish, and wildlife, and with recreation in and on these waters.
Persons wishing to comment upon or object to the proposed NPDES permit or to request a public hearing, should submit their comments or requests in writing no later than 30 calendar days after the date of this notice, either through E-mail at cleanwaterbranch@doh.hawaii.gov or by mail at P.O. BOX 3378, Honolulu, Hawaii 96801-3378.
Copies of the public notice permit recommended by CWB and other information are available for public inspection, Monday through Friday (excluding holidays) from 7:45 a.m. until 4:15 p.m., at the DOH Clean Water Branch office located at 2827 Waimano Home Road, Room 225, Pearl City, Hawaii 96782. Copies may be bought. Electronic copies of the proposed public notice permit and other information are also available online at https://health.hawaii.gov/cwb/clean-water-branch-home-page/public-notices-and-updates/.
For more information or if you have special needs due to a disability and require aid in inspecting and/or commenting on the public notice permit and related information, please contact Mr. Reef Migita, Supervisor of the Engineering Section, Clean Water Branch, at the above address or (808) 586-4309 (Voice) as soon as possible before the end of the comment period. For those who use a TTY/TDD, please call through Sprint Relay Hawaii, at 1 711 or 1-877-447-5991. If a request for assistance is made after the end of the comment period, the CWB will try to fulfill the request. However, fulfillment prior to a final determination cannot be guaranteed. Requests submitted as early as possible are more likely to be fulfilled.
All written comments and requests received on time will be considered. If the Director determines that there is significant public interest, a public hearing may be held after at least 30 calendar days of public notice.
If CWB believes, after considering all timely written comments at any public hearing that may be held, that no substantive changes to the conditions of the public notice permit are necessary or warranted, then CWB may recommend to the Director that the NPDES permit be issued.
Please notify anyone you know who would be interested in this matter.

DARRYL LUM, P.E.
Clean Water Branch Chief
(SA1522504 3/16/26)