Definitions and Background:
• 1972: Clean Water Act states that all bodies of water must be safe for recreation activities, thus enforcing new regulations on pollution
• New York City does not have any technology to deal with CSOs or Combined Sewer Overflows which occur when rain floods the bioremediation sites, forcing pollution plants to release sewage into the waterways to alleviate the pressure caused by flooding
As stated in PLANYC, the plan for water quality is made up of 10 initiatives, which include but are not limited to:
I. Long Term Control Plan (LTCP) to deal with CSO
The Department of Environmental Protection, as well as the State Department of Environmental Conservation, has mandated that New York City submit and implement Long Term Control Plans (LTCPs) that will address the Combined Sewage Overflow (CSO) problem. As stated in the LTCP, New York City plans to:
A. Mitigation: What NYC is currently doing to decrease CSO
1. improvement of the current infrastructure has doubled the volume of flows that sewage plants can handle on a normal day of dry weather
B. Adaptation: (taken directly from PLANYC Water Report)
1. Aeration: pumping oxygen into water to encourage aquatic life
2. Destratification facilites that will distribute oxygen by churning the water
3. Maximizing the amount of waste water conveyed to the treatment plant by optimizing sewers
4. Creation of force mains that will divert CSO into larger bodies of water so that it can more easily assimilate sewage
5. Dredging: the removal of sedimented bio-solids on the bottoms of NYC’s bodies of water
6. Other enhancements will reduce the amount of floating debris in the water through creation of netting facilities
II. Upgrade the “wet-water” capacity of treatment plants
– this is especially important because although treatment plants can store about twice its volume on a dry day, what matters most is its ability to store water without overflow on days where the city experiences rain.
III. Conversion of Combined Sewers into High Level Storm Sewers (HLSS)
1. High Level Storm Sewers or HLSS capture water from rainfall before it enters NYC’s pipes, and therefore reduces the probability of CSO
2. The city plans to integrate HLSS into new projects
3. The city also plans to increase the number of plants so that these plants can also retain water and decrease the chance for CSO
IV. Creation of Green roofs
Economic Challenges
Climate change forces many economic issues in NYC. We will examine the ways that environmental programs quantify the CSO issue so that we can adequately track its progress. We will also analyze the kinds of plans that NYC officials have been proposing to mitigate the storm water and CSO issues and their subsequent costs. Many believe that the most cost effective way of dealing with the limited fresh water issue is by first dealing with NYC’s sewage systems – once the sewage system and water ways have been “fixed” it will be easier to then deal with transporting fresh water (possibly uphill). The main question we need to ask ourselves as New Yorkers is how much are we willing to pay to for our water and the infrastructure that may need to be rebuilt to transport it, etc.? What are the projected prices, and what’s the price we, as a city in severe debt, are willing to pay?
As we face the dawn of the second half of the 21st century, we confront the problem of ensuring that all of New York City’s residents have continued access to clean water, even as the population grows to a projected one million people. Our research project anticipates this future population growth, and takes a two-pronged approach the issue of water: We examine ways to ensure future access to water, and methods to ensure the water is clean.
We examine access to water by looking at projections for the future. When will our water sources be exhausted at our current rate of usage? We look at London’s and Amsterdam’s water systems to see how they resolve flooding difficulties and risings sea levels, both of which trouble NYC in the present, and will in the future. We examine options including desalination of ocean water and the the creation of closed sewer/gray water systems.
To ensure that the water New Yorkers drink is clean, we first investigate the most pressing case of dirty water: combined sewer overflow (CSO). We look at the history and causes of CSOs, as well as ways to reduce or eliminate them, hence creating a supply of clean water.
What are CSOs?
NYC’s Sewer System
All across New York City, combined-sewer systems (CSS) are used to collect sewage, storm water, and industrial waste. All of this effluent flows through one pipe — hence the name combined sewer system. Approximately 70% of city sewers are combined. On a typical day, the CSS can hold all the matter that flows through its pipes. However, when rain is heavy or when snow begins to melt, the CSS begins to fill with the storm water. The mix of the storm water and waste begins to rise until the CSS reaches capacity. When the CSS exceeds capacity, all the waste– untreated — is offloaded directly into the water. This is combined sewage overflow (CSO).
A closed sewer system (CSS) leads to combined sewage overflow (CSO). Photo credit: U.S. Environmental Protection Agency
