Evaluation Of Water Usage And Conservation Strategies At Wastewater Treatment Plants

Last Modified: May 14, 2013


  • Anni Luck - Hazen and Sawyer
  • Vlada Kenniff - Bureau of Environmental Planning & Analysis, NYCDEP

The New York City Department of Environmental Protection (DEP) provides 1.2 billion gallons of water to about 9.3 million people daily in the five boroughs of NYC and to many upstate communities. The Delaware Aqueduct, which conveys more than half the total daily supply, is experiencing significant leakage (15 to 35 mgd) in the Rondout-West Branch Tunnel segment. To ensure future system reliability and supply, DEP will commence construction of a three-mile bypass tunnel around the compromised aqueduct segment in 2013 with estimated completion in 2020. Once the shaft and bypass tunnel are constructed, the aqueduct would be shutdown, drained, and connected to the bypass. This repair work and shutdown is estimated to take between 6 to 8 months; during this period up to 50% of current water supply may not be available.

To supplement water supply during this shutdown, DEP will implement several supply augmentation programs, one of which is a comprehensive water conservation program termed Water for the Future Demand Management. This program entails implementing water conservation strategies across various types of government buildings and facilities. The focus of this paper is on evaluating water usage and conservation strategies for wastewater treatment plants (WWTPs). DEP owns and operates fourteen WWTPs with a collective treatment capacity of 1.8 billion gallons of wastewater a day. These facilities collectively treat on average 1.2 bgd and utilize city water for various applications during the treatment of this wastewater.

This presentation describes the systematic approach conducted to achieve the following primary objectives:
i) Estimate the total water consumption at each WWTP
ii) Identify how city water is used at each WWTP
iii) Identify processes that can utilize plant effluent instead of city water
iv) Identify opportunities for water conservation measures
v) Estimate costs (capital and labor) associated with these conservation measures
vi) Perform a cost-benefit analysis ($/1000 gallon water savings)
vii) Develop water conservation recommendations for WWTPs

Findings from the above analyses will be presented and show that there is good potential for water usage savings across all WWTPs. Details for a sample case study in particular will illustrate how conservation measures can potentially reduce city water usage by up to 78% (1.24 mgd) at this one WWTP through upgrades and repairs to existing equipment and infrastructure.

For more information, please contact the author at aluck@hazenandsawyer.com.

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