Supporting city expansion

Oswego, a city in New York, US, is a changing community. A resurgence of the downtown area and revitalisation of historic neighbourhoods alongside the Lake Ontario waterfront is driving population growth and putting pressure on existing infrastructure.

The 120-year old West Side sewer system for the City of Oswego (City) has been earmarked for upgrade and rehabilitation to eliminate unpermitted overflows and support further expansion.


The City first retained GHD as its primary engineer in 2017 to manage a complex program to remedy unpermitted wet weather overflows and to meet compliance requirements.

The West Side sewer system is served by both a sanitary sewer system and a combined sewer system. Both systems experience unpermitted overflows during wet weather caused in part by infiltration and inflow into the ageing sewer system infrastructure.

In 2010, the City entered into a Consent Decree with the New York State Department of Environmental Conservation (NYSDEC) and the United States Environmental Protection Agency to resolve these issues and meet 42 compliance requirements by 2022, with the majority required by 2015.


GHD represented the city as technical advisors throughout the negotiations of the Consent Decree, offering services from public participation and sewer system modelling to performing economic and alternative analyses.

“We performed design and construction phase services for the disinfection facility, Excess Flow Management Facility upgrade and 30,000 linear feet (9144 m) of sewer separation,” explains Michael Tamblin, GHD Principal. “We also completed a sanitary sewer evaluation survey to assess the condition of the sewer system and mitigate potential sources of infiltration and inflow.

“As well as being directly involved in the engineering design and construction administration of various projects, GHD assisted the City through many other facets of the program, including applying for low-interest financing and grant money. We also completed water quality sampling, development of the post-construction monitoring system and more.”


To date, 36 of the 42 compliance requirements in the Consent Decree have been completed. GHD has successfully managed each of these requirements on time and under budget, which has put the City on track to meet the ultimate goals of eliminating the unpermitted overflows and minimising the volume of combined sewer overflows discharged into the Oswego River.

“We maintained a high level of safety awareness throughout the program,” adds Michael. “We are proud to report that there have been zero recordable incidents on any of the projects we have worked on to date.”

To help fund these upgrades, GHD has been successful in assisting the City with obtaining low-interest financing for the various projects and USD4 million in grant money.

William J Barlow, the Mayor of Oswego, said, "The City of Oswego's West Side Sewer Separation project is a major undertaking for us, impacting a large portion of our city for an extended period of time. As we execute this massive project, it has been a pleasure to work with GHD as they've been extremely responsive, timely, responsible and accountable.

“Partnering with GHD on this project has made the entire process run on time and with ease. We look forward to continuing our work with GHD on our projects and appreciate their focus and commitment to the City of Oswego."

Project works are ongoing with final completion earmarked for 2022.