Planning Comprehensive Water Quality Based CSO Controls For A Polluted Urban Tributary

Last Modified: Nov 17, 2009


  • Curtis D. Courter and Peter Young, Hazen & Sawyer
  • James Mueller and Keith Mahoney, NYC Department of Environmental Protection

The Newtown Creek is an urban tributary to the East River in New York City on the border between the boroughs of Brooklyn and Queens. Originally a stream draining the uplands of Western Long Island, the system of small tributaries and tidal marshes has been extensively altered by urbanization, which has largely modified the course and channel of the Creek, filling the inland streams and widening and deepening the downstream end. In addition, the drainage area has increased over the years from approximately 5,300 acres to 7,650 acres of largely impervious urban landscape. The first kerosene and modern oil refineries in the United States transformed the Creek into an industrial waterway and in 1865 the City surveyor’s advice against plans to run sewer lines to the Creek went unheeded and the City began dumping raw sewage directly into the Creek. At the end of the 19th Century, areas adjacent to the Creek had the highest concentration of industry in the United States and by the 1930s, the Creek was further channelized and deepened to accommodate heavier shipping traffic and thus emerged as a major shipping hub. The Creek became home to such businesses as sugar refineries, canneries, copper wiring plants, and petroleum and oil refineries. With free reign to dispose of unwanted byproducts, these industries soon transformed Newtown Creek into one of the dirtiest waterbodies in America, with water quality degradation only accelerated by the cumulative affects of waterbody and watershed alterations and the lack of wastewater treatment (primary treatment began in 1967 and secondary treatment is only now under construction). Today the Creek’s legacy of pollution is still apparent as oil seeps through shoreline bulkheads from an underground oil spill estimated to be as much as three times larger than that from the Exxon Valdez. In addition to the remaining industrial pollution, the Creek still receives nearly 2 billion gallons of untreated CSO and stormwater discharges in an average year from 23 CSOs and over 200 other direct discharges, which lead to frequent high bacteria levels and anoxic conditions.

In 1984, a city-wide CSO abatement program was developed that focused on establishing planning areas and how facility planning should be accomplished. This initial program defined four open water project areas and four tributary project areas, including one for the Newtown Creek, and these facility plans were incorporated into the State Pollutant Discharge Elimination System permit. The resulting CSO facility planning effort for Newtown Creek, began with the issuance of a Draft Facilities Plan Report in January 1993, a full 16 months before the USEPA’s April 1994 Combined Sewer Overflow Policy was promulgated, and culminated in 2003 with a Final Facility Plan Report, that included CSO abatement and water quality improvement projects, which are included as milestones in the City’s Consent Order. However, the Consent Order acknowledges that this plan is not a final conceptual level design and allows the City to propose final modifications to the scope of the projects set forth in the 2003 CSO Facility Plan.

As such, facility planning for the Newtown Creek waterbody/watershed was undertaken as part of the ongoing City-Wide Long Term CSO Control Planning Project required as part of the 2005 Consent Order.

As part of the effort to finalize the conceptual level design for facilities to address water quality issues within Newtown Creek, the analysis first looked at the total universe of CSO and water quality technologies available from broad categories such as source control, inflow control, sewer system optimization, sewer separation, storage and conveyance, treatment, receiving water improvement, and solids and floatables controls. Then, through a broader analysis of the assessment area, watershed characteristics, existing sewer system facilities, waterbody characteristics, other waterbody improvement projects, and public participation and agency interaction, technologies that could be reasonably implemented within the Newtown Creek watershed were short listed for further analysis using the most up to date planning tools (GIS, hydraulic sewer system models, and receiving water models with hydrodynamic and water quality components) to determine potential benefits. At the next level of alternatives analysis, the short listed technologies were developed into alternatives specific to Newtown Creek. These alternatives were developed beyond the conceptual level, to include preliminary design layouts, specific sites and exact routes so that the alternatives could be accurately portrayed in the models, and so that an accurate determination of the probable total of all hard costs, soft costs and ancillary costs associated with a particular alternative could be made. The lowest cost alternatives for particular levels of benefit, both in terms of projected CSO reductions (volume and events), and water quality impacts, were grouped into water quality improvement plans aimed not only at meeting existing water quality standards, but providing a reasonable range of alternatives that were capable of addressing specific waterbody issues. At the final level of screening, the water quality improvement plans were compared through knee-of-the-curve analyses based on CSO reduction metrics, attainment of existing water quality standards, and attainment of the next highest use classification for New York State Waters. An approvable plan was selected based on these quantitative analyses as well as on a review of conformance with narrative water quality standards and considering waterbody goals set by several different stakeholder groups.

The approvable plan was submitted to the state permitting agency in June 2007. The plan, which follows the demonstration approach, includes implementation of low impact developments and best management practices (LIDs/BMPs), a relief interceptor, regulator modifications, environmental dredging, in-stream aeration, floatables control facilities, and a 40 MG CSO capture tunnel. The plan includes an enforceable phased implementation schedule and is projected to fully attain the existing SD state water quality classification requirements after implementation of the first phase. After implementation of the second phase, which includes the relief interceptor and storage tunnel, the waterbody is projected to attain the next highest use water quality classification, I, which allows for fish propagation and secondary contact recreation. The implementation schedule calls for full implementation of both phases in approximately 20-years and it is estimated that it will cost over $3.8 billion dollars when escalated based on the implementation schedule.

Several elements of Phase 1 are already being implemented. Construction of the first aeration facility is scheduled for completion in 2008, and evaluation of LIDs/BMPs is ongoing.

For a copy of the full paper, please contact the author at

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