Sand Island Wastewater Treatment Plant Primary Expansion

Location: Oahu, Hawaii
Client Name: City and County of Honolulu, Department of Wastewater Management
Date Completed: 2005
Construction Cost: $80,000,000
Disciplines Applied: Water & Wastewater Engineering

Project Description:

The Sand Island Wastewater Treatment Plant is a primary treatment facility serving metropolitan Honolulu (the largest WWTP facility in the State of Hawaii). The facility began its operations in 1978 and services an area stretching from Kuliouou Valley on the East side of Honolulu to Aliamanu on the West side of Honolulu. The WWTP has not undergone major changes to its processes since its origin. RMTC was contracted to provide professional services for the modification of the Sand Island Wastewater Treatment Plant. The plant is undergoing major system modifications since it was constructed due to: (1) Capacity Expansion, and (2) Waiver of Secondary Treatment according to Section 301(h) of the 1981 Municipal Wastewater Treatment Construction Grants Program.

RMTC initially prepared a preliminary engineering report that addressed the future plant expansion from 82 MGD to a 90 MGD facility. RMTC’s design team was then tasked to design a new Headworks facility, a chemical facility, two new primary clarifiers, new odor control systems, retrofit existing clarifiers and influent channel, retrofit sludge tanks and gravity thickeners.