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New York City's Wastewater Treatment System

Pollution Control Programs

The Industrial Pretreatment Program (IPP)

A federally authorized program, works to control commercial discharges by requiring industries targeted by federal and local pretreatment regulations to remove specific toxins from their wastewater before it is released into the City's sewer system.

IPP helps to protect the sewers, the wastewater treatment plants and the City's receiving waters. The EPA requires approximately 1,500 municipalities around the country to implement industrial pretreatment programs. DEP has been a control authority since January 1987. DEP's program is annually audited by either the New York State Department of Conservation (NYSDEC) or the EPA. Since 1987, the amount of heavy metals being discharged by regulated businesses fell from over 2000 lbs/day to 37 lbs/per day.

Two successful IPP programs are the Persistent Pollutant Track-down Program and the Perchloroethylene (PERC) Reduction Program.

Persistent Pollutant Track-down Program:

A collaborative effort between DEP and the DEC. Together, the two agencies work to track down the sources of PCBs (polychlorinated biphenols), PAHs (Poly-Aromatic Hydrocarbon), mercury and other organic chemical compounds found in our harbor waters.When businesses responsible for pollution are identified, DEP and DEC work with them to help establish improved (or first-time) methods of pretreatment.

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PERC Reduction Program

Enforces special sewer regulations that require dry cleaners to implement a best management program to limit perchloroethylene (PERC) discharges into the sewer system. (PERC is a solvent widely used by drycleaners.) DEP regularly inspects the City's dry cleaning establishments to make sure owners are adhering to PERC regulations.

DEP regulates industrial users of the public sewers in a variety of categories such as electroplating, metal finishing, organic chemical and pharmaceutical manufacturing. As part of the IPP, DEP issue permits setting forth applicable pollutant limits as well as wastewater sampling and reporting requirements. DEP also regularly inspects IPP facilities and performs its own wastewater monitoring to ensure that the regulated facilities are in compliance with pretreatment standards.Whenever it is determined that a facility is not meeting its permit limits due to a failure in operating and maintaining its pretreatment system, or not installing the proper equipment, DEP will require, through Notice of Violation and/or Commissioner's Order, that remedial action be taken.

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Pollution Prevention Program

Pollution Prevention Programs focus on reduction of toxins from commercial sources through education and information about “green” technology and good business management practices.

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Dry Weather Discharges

In 1988 DEP initiated the Shoreline Survey Program. Its purpose was to identify and eliminate sources of raw sewage discharge into the City's waters during dry weather. This program in conjunction with a more recent one, DEP's Sentinel Monitoring Program, has enabled the elimination of 99 percent of dry weather discharges. DEP continues to work on controlling the remaining discharges by constructing new sewers and taking enforcement action to correct illegal connections to storm sewers.

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Discharges of grease (cooking oil) into the sewer system from restaurants and other food related establishments can block sewers, causing backups and bypasses. To ensure proper disposal of grease, and prevent sewer backups, the City requires by law that grease generating establishments correctly install, operate and maintain properly sized grease interceptors. Special DEP staff inspect these establishments to make sure that the required equipment is installed and working properly. DEP has initiated an educational program to address grease discharges from the over 21,000 restaurants in New York City. The Grease Response Education and Strategic Enforcement Program approaches the problem with a combination of education materials, including foreign language material, which are distributed to restaurants in target areas. Sewer blockages can also be caused by grease and oil improperly disposed of in kitchen sinks and toilets in homes and apartments.

Grease thrown down kitchen sinks in homes and apartments can also cause sewer blockages.

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Pumping Station Telemetry

Telemetry is the ability to send “real-time” (as it is happening) data to a remote terminal (computer) by utilizing a radio signal or telephone line. Since 1998, telemetry has been in operation at DEP's 95 wastewater pumping stations enabling personnel to check the daily operation of these facilities from a remote computer. This program has already succeeded in reducing dry and wet weather discharges by allowing DEP pumping station operators to respond more rapidly to station malfunctions, breakdowns and other potentially serious system disruptions.

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Combined Sewer Overflows (CSO)

The completion of the Red Hook WPCP (on the lower East River in Brooklyn) in 1987 ended the last, permitted, dry weather discharge of raw sewage into New York Harbor. However, the City still faces the problem of combined sewer overflows. As noted earlier, CSOs can occur in wet weather when wastewater treatment plants and/or parts of the sewer system fill to capacity with rain or snow. To relieve pressure on the already filled to capacity wastewater treatment system, the excess flow is forced into the open waters of a river, bay or inlet. These overflows can increase the number of harmful bacteria and add other organic pollutants that consume dissolved oxygen, which marine plants and animals need to survive. CSOs also carry trash and litter washed from streets and may contain toxic chemicals.

As a part of a multi-year, $1.8 billion CSO Abatement Program, the City is building retention tanks to hold the overflows near heavily impacted bays and tributaries, installing separate sewers where no sewers exist, and exploring other innovative solutions. The planning, design and construction of some of these facilities has already begun. In addition to construction of these retention tanks, CSO pollution has already been noticeably controlled through improvements in DEP's operation of its treatment plants and intercepting sewer system during wet weather.

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Floating debris

Litter that washes down storm drains in the street can easily wind up in local waters and on City beaches. This unsightly pollution, called floatables, can kill birds, turtles and other marine animals that mistake trash — especially plastic — for food. Street litter that goes to the treatment plants must be separated from the wastewater so it won't damage plant equipment. Litter can also clog storm drains and cause sewer backups and flooding.

The City is also tackling the problem of debris with a multi-faceted program that includes increased street cleaning in critically located neighborhoods; regular catch basin maintenance; replacement of hoods on catch basins that trap debris before it enters the sewer system; the booming and netting of sites where combined sewer overflows enter local waters; operational improvements at Sewer backup — caused illegal discharge of grease into the sewer system treatment plants and collections systems, and a fleet of skimmer vessels that collect floatables from the open waters.

To eliminate illegal shoreline dumping (another source of floatable materials), DEP set up a Shoreline Dumping Prevention Program to monitor the City's many miles of shoreline for evidence of recent illegal disposal activities. Findings are reported to the Department of Sanitation (DOS) Police for follow-up and possible apprehension of illegal dumpers.

Additional programs credited with limiting the discharge of floatables into the Harbor include the use of demolition vessels to remove decaying piers, and collaborative efforts by the US Army Corps of Engineers, EPA and DEC to collect large floatable debris and skim litter from the open waters and shorelines.

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Water quality monitoring

To gauge the effectiveness of wastewater treatment plant programs, water quality is analyzed at 35 sampling stations throughout New York Harbor. Since 1970, DEP's Annual Harbor Water Quality Survey has tracked trends showing increases in dissolved oxygen and decreases in fecal coliform — indicators of improved water quality. The diagrams (“Fecal Coliform In Surface Waters”) detail these improvements through fecal coliform measurements. Before 1985, there was a large area suitable for “NYS Fishing Standards” (monthly geo. mean <=2,000 counts/100mL) and very few areas were labeled as suitable for bathing. By 1992, the number of “Fishing Standard” areas had decreased dramatically while the bathing areas (monthly geo. mean <= 2,000 counts/100mL) had increased. By 1999, the “Fishing Standard” indicator was found only at Flushing Creek, and Upper East River. By 2009, all of the waterways around New York City were suitable for bathing. (See Diagram “Fecal Coliform in Surface Waters.”) There have been no beach closures since 2001, except for precautionary closings, during the 2003 blackout.

Area-wide decreases in sewage loading have resulted in greater environmental improvement in the Harbor. Indicative of this improvement has been the increase of dissolved oxygen (DO) to levels that better support aquatic life.

Harbor Survey monitoring has documented significant Harbor-wide increases in DO concentrations  over the the 30 years (see Graph “Harbor-Wide Dissolved Oxygen”).  Average summer surface and bottom DOs have maintained above NYS Bathing Standard (5 mg.L) since early 1990s.


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Regulator Telemetry System “Enhanced Beach Protection Program”

Regulator telemetry systems are, at present, fully installed and operational at 102 regulators. (A regulator is a device used in New York City's combined sewers to control or regulate the diversion of sewage flow to the treatment plants during dry and wet weather.) These systems are links to an internet software package that allows DEP to monitor each individual site continuously. The telemetry system transmits alarms as soon as the level of the water reaches a predetermined elevation in the regulator. DEP initiated the “Enhanced Beach Protection Program” (EBPP) in 1997 to monitor pumping stations and regulators that could have an impact on the City's beaches. The immediate goal of the program is to prevent negative water quality impacts that may result as a consequence of unintended dry weather bypasses and, ultimately, to prevent beach closures. This program incorporated the use of telemetry to replace site visits. The successful implementation of the regulator telemetry system has had a significant impact in the reduction of raw sewage bypasses, most important during the recreational beach season.

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Carbon, nitrogen and phosphorus are substances that are excreted by humans and thus found in wastewater. Excess nutrients can stimulate the growth of algae and other aquatic plants.When these plants die and decompose, they may reduce the amount of oxygen in the water. This condition, called hypoxia, can affect the survival of fish and other aquatic organisms.

Nutrients can also get into wastewater from industrial discharges, common household detergents and cleaners, runoff from streets and lawns and air pollutants that fall to the ground. Treatment plants cannot remove all nutrients from the wastewater. They can be reduced by controlling pollution that comes from lawns, farmland, streets and construction sites.

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Water Waste

On average, each New Yorker uses about 100 gallons of water daily — twice as much as residents of most European cities and many other places in this country. Naturally, the more water we use, the more wastewater the treatment plants must process. Since each New York City plant is designed to handle a certain amount of wastewater, when too much comes into a plant, it reduces its spare capacity. Unless flows can be lessened, added treatment capacity may be required.

DEP has initiated a comprehensive program to encourage water conservation and to reduce flows into the City's treatment plants. The program, which began in 1989, included the following:

  • installation of almost 630,000 residential water meters;
  • electronic water main leak detection;
  • commercial and residential surveys to locate leaks within buildings;
  • incentives to replace old toilets and showerheads with low flow fixtures;
  • permanent and seasonal year-round restrictions on water use such as watering lawns, and hosing sidewalks;
  • installation of fire hydrant locking devices;
  • public education for school children and City residents.

These programs and others, have proven successful and cumulatively together have reduced water consumption in the City by approximately 200 million gallons per day in the last ten years.

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Reservoir Levels

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