Review of the New York City Watershed Protection Program (2020) / Chapter Skim
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8 Wastewater Programs
8 Wastewater Programs
Pages 223-248
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From page 223... ...
The programs that govern wastewater treatment in the watersheds also have an impact on the local ecosystem, in that effective wastewater treatment protects the land, the groundwater, and local streams from pollutants and/or excess nutrient loads. Finally, the wastewater programs have strong community vitality elements, in that a valuable public service is being provided at very low cost to watershed residents and businesses.
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From page 224... ...
is far more important than removing nitrogen. The specific watershed protection programs that manage wastewater treatment include the Wastewater Treatment Plant Upgrade Program, the New Sewage Treatment Infrastructure Program, and a number of programs for replacement and proper maintenance of septic systems in the watersheds that provide NYC's drinking water.
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. BOX 8-1 Wastewater Treatment Plant Tertiary Treatment Processes Centralized wastewater treatment can include process steps generally referred to as preliminary treatment, primary treatment, secondary treatment, and tertiary treatment.
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The New Sewage Treatment Infrastructure Program, a voluntary program, was created to assist these communities by providing funding for the study, design, and construction of WWTPs, community septic systems, or septic maintenance districts. A community septic system is a system that treats wastewater from multiple structures; the system can be constructed such that each structure is equipped with a septic tank and a common leach field receives flow from the community's septic tanks.
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From page 227... ...
expenses for the private WWTPs and approximately $3.5 million in O&M for the New Sewage Treatment Wastewater Infrastructure Program. Future funding for the O&M of the City-owned WWTPs is not part of the Watershed Protection Program budget, although it is a NYC DEP expense.
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From page 228... ...
Projected Ten-year Program 1993- 2019 2020-2028 1993- 2019 Projections City-owned WWTP $271,264,000 N/A N/Aa N/Aa upgrades Private WWTP upgrades $462,169,000 $60,000,000 $144,891,000 $147,192,000 New Sewage Treatment $199,986,000 N/A $37,640,000 $34,840,000 Infrastructure Program a Future funding for the City-owned plants is not considered part of the budget of the Watershed Protection Program, although it is part of NYC DEP's overall budget.
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From page 229... ...
Figure Courtesy of NYC DEP. TABLE 8-2 Summary of 26 Wastewater Treatment Plants That Discharge to West-of-Hudson Surface Waterbodies Annual WWTP Septics Number Number 2010 Population Average Basin Flow Displaced of of Septic Population /Acre Flow (MGD)
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FIGURE 8-2 Surface-discharging wastewater treatment plants east-of-Hudson. Figure in color at https:// www.nap.edu/catalog/25851/.
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From page 231... ...
Both plants were upgraded to TABLE 8-3 Comparison of Cannonsville Reservoir Basin Wastewater Treatment Plant Permitted Flow and Total Phosphorus Concentrations Versus Actual Flows and Concentrations, 2014-2018 Average TP Effluent SPDES Permitted Average Flow WR&R TP Limit WWTP Concentration Flow (MGD)
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TABLE 8-4 Summary of West-of-Hudson Wastewater Treatment Plant Phosphorus Loading to Watersheds Pre-upgrade Total Average 1998 WWTP Flow Average Flow Watershed Phosphorus (TP) a Post-upgrade (MG/year)
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. A schematic and summary of a conventional septic system, which includes a septic tank and a soil adsorption system, is presented in Box 8-2.
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A typical septic system consists of a water-tight septic tank and a drain field, also commonly referred to as a leach field or soil adsorption field. The septic tank must be constructed of concrete, fiberglass, polyethylene or other durable material not subject to corrosion, frost damage, or cracking.
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. Small Business Septic System Rehabilitation and Replacement Program The Small Business Septic System Rehabilitation and Replacement Program commenced in 2007 to fund the rehabilitation or replacement of failing septic systems serving eligible small businesses.
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Septic Maintenance Program The Septic Maintenance Program provides a 50 percent reimbursement of septic tank pump-out costs to all owners of WOH septic systems. Routine inspection and pump-out of septic systems every three to five years is important to ensure the proper treatment of sanitary waste.
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Today, there are approximately 550 septic systems in the basin. The NYC DEP records indicate that 24 septic systems in the Kensico Reservoir basin have been addressed by the Septic Rehabilitation and Replacement Program since 2008.
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From page 238... ...
A properly designed septic tank removes 49 percent of the influent carbonaceous biochemical oxygen demand (CBOD5) and 74 percent of the TSS, and an appropriately sited, constructed, soil adsorption field will continue treatment and provide total removal efficiencies of 90–98 percent for CBOD5 and TSS and 99–99.99 percent removal of fecal coliforms (EPA, 2002)
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From page 239... ...
39,000 WOH septic systems, including the Kensico Reservoir basin, would alter the then current loading of pollutants in terms of total phosphorus, TSS, fecal coliforms, viruses, Giardia cysts, and Cryptosporidium oocysts. Both conventional septic tanks and ATUs (which were considered to be best available control technology)
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From page 240... ...
A shallow adsorption trench system is appropriate for soils with adequate infiltration characteristics but inadequate soil depth to support a standard soil adsorption system. Shallow adsorption trench systems generally locate the drain pipe following contours at or within 15 cm of the soil surface, dependent on soil and site characteristics, and cover the pipe with some sort of exclusionary barrier (e.g., geotextile or infiltrator chamber, Figure 8-6)
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From page 241... ...
The findings of the Septic Siting Study included documentation of surrogate pathogens observed beyond the 100-ft setback required for the septic system drainage field by the Watershed Rules and Regulations. Given the proximity of residences in the WOH region to waterbodies (more than 11,000 parcels are within 50 ft of a watercourse, Meyer 2018a)
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BOX 8-3 The Septic Siting Study NYC DEP conducted a Septic Siting Study (NYC DEP, 1999) to evaluate the impact of individual septic systems on the water quality of proximate streams.
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From page 243... ...
In addition, given the improvements in soil adsorption field technology, and the site characteristics in both the WOH and EOH watersheds, alternative soil adsorption fields should be incorporated into any new or replacement designs. Given the proximity of many of the septic systems to watercourses in the NYC watersheds and the consequences of system failure, there is a strong case to require best available control technology for both the septic tank and soil adsorption field to ensure proper treatment of wastewater and protection of NYC source water.
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From page 244... ...
Assuming an average cost of $20,000 to replace a system, the program would need to maintain a funding level of $10 million to 30 million a year into the future. This funding level is an underestimate, considering that costs to integrate ATUs and alternative soil adsorption systems into the Septic System Program would further increase costs, perhaps by 30-50 percent in capital expenses and $200-300 a year in power, maintenance, and inspection costs per system.2 CONCLUSIONS AND RECOMMENDATIONS The attention given to improving centralized wastewater treatment in the NYC watershed has made substantial impacts in terms of reducing pollutant concentrations in the water supply reservoirs (see Chapter 4)
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Further, given the topography and soil characteristics of the Catskill region, alternative soil adsorption systems (shallow adsorption, mound, or drip systems) should be required to ensure more complete wastewater treatment.
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2013. Comparative analysis of effluent water quality from a municipal treatment plant and two on-site wastewater treatment systems.
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Presentation at the 1st meeting of the NASEM Committee to Review the NYC DEP Watershed Protection Program. Saugerties, NY.
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