Haverstraw Water Supply Project
I. Overview
Rockland County has encountered phases of inadequate water supply since the 1990s, due to periodic drought and increasing demand from population growth. The New York State Public Service Agreement called upon United Water, the region's drinking water supplier, to develop a new source water to meet growing demand as part of a three-year rate plan for Rockland County. United Water proposed the Haverstraw Water Supply Project, a desalination plant in the Hudson River that was met with protest and debate among the residents of Rockland County and environmental watchdog organizations. Many citizens and environmentalist groups are concerned that desalination would be costly for consumers and the environment, and would require large amounts of energy and emit greenhouse gases [1]. The resultant water quality has also been called into question. United Water claims in their environmental impact assessment that desalination is the most environmentally friendly and inexpensive option for Rockland County [2]. Many have called this conclusion into question since desalination is generally regarded as unsustainable and expensive. Desalination is typically a last-resort solution to water scarcity, and is almost invariably only utilized in regions lacking in alternative water resources. Rockland County's annual rainfall is above average for the United States, and is considerably higher than regions that resort to desalinated water as a potable source. Environmental groups have suggested that there are more sustainable options for Rockland County. Groups have proposed increasing water efficiency, updating leaky infrastructure, encouraging water conservation, stormwater management, and water reuse [1]. Ultimately, a soft water management strategy that incorporates multiple solutions may be the best option for Rockland County. All options should be evaluated on the basis of cost, energy usage, greenhouse gas emissions, resultant water quality, and ecological impact.
II. Current and Projected Water Supply and Consumption
United Water currently meets Rockland County's water demand with a combination of surface and groundwater. Two surface water sources, Lake DeForest and Letchworth Reservoirs, supply 32% of the county's water. Another 25% of demand is met by the Ramapo Valley Well field. An additional 50 wells located throughout the county meet the remaining 43% of the water demand [2].The majority, 89.2%, of water accounts under United Water are for residential single family homes, which consume on average 13.92 mgd, or 46.2% of the total water demand in Rockland County. Apartments and multi-family homes account for 11.5% of water use and commercial consumption accounts for 9.7% of water use. The other major contribution to water consumption comes from non-revenue water, accounting for 19% of total daily water consumption. Non-revenue water refers to incorrectly metered water, process water, and water lost through leakage. Rockland residents use 62.15 gallons per capita per day (gpcd) in non-summer months, which is approximately 10% below the national average. In the summer months, water consumption increases by 11.54 gpcd. The total average daily water demand for Rockland County is 29.85 mgd. United Water forecasts that total average annual demand will reach 34.4 mgd by 2018, thereby exceeding the average day supply of the current water resources. Based on growth trends and predicted demand into the next few decades, United Water aims to produce another 2.5-7.5 mgd [2].
III. Proposed Desalination Plant
Analysis of projected water supply and demand led United Water and Rockland County to determine that a new source water was necessary, and ultimately led to the development of the Haverstraw Water Supply project. This project proposes desalinizing Hudson River water to provide a drought-tolerant water source for Rockland County. Hudson River water is brackish [3], meaning that it is more saline than fresh water, and too saline to be suitable as drinking water, but less saline than ocean water, which has a salinity of 3% or greater.
A. Reverse Osmosis Technology
The plant would use reverse osmosis to filter out salts and raise the water quality to meet drinking water standards. Reverse osmosis, as the name implies, is the reverse of a phenomenon known as osmosis. In osmosis, water (or any solvent) moves through a semi-permeable membrane from a low-concentration solution to a high-concentration solution in order to dilute the high concentration solution, thus making the two solutions equal in concentration. The pressure at this equilibrium is the osmotic pressure. In reverse osmosis, the osmotic pressure must be overcome in order to push solvent from the highly concentrated solution into the less concentrated solution. In a reverse-osmosis drinking water plant, brackish water (or saltwater) would be on one side of the membrane, and pure water would be on the other. External pressure equal to osmotic pressure would then be applied to the saline water, forcing it through the membrane, leaving the solutes behind as a waste product [4].
The Haverstraw desalination plant would be desalinating brackish water from the Hudson River. In its first phase, the plant would produce 2.5 mgd. Desalination by reverse osmoses typically takes 2-3 gallons of saline water for every one gallon produced, requires extensive energy inputs, and produces saline wastewater [2].
B. Cost
Original estimates put the cost of constructing the desalination plant at $98 million. The company would recover these costs plus a profit through a surcharge on consumers' water bill. The operating cost for desalinated water, based on 2008 energy costs, is estimated to be $1.91 per 1000 gallons, compared with the national average of $1.50 per 1000 gallons [2]. The operation costs of the plant will rise as energy prices are expected to rise in the future [1].
C. Energy and Water Consumption
The desalination plant will use between 4,427 and 6,520 kWh of electricity per million gallons of water, and will require 10 mgd for every 7.5 mgd produced. Generally electricity consumption of drinking water treatment plants does not exceed 3500 kWH per million gallons, and produce the same amount of potable water that is withdrawn from the source [2].
D. Greenhouse Gas Emissions
The desalination plant would require energy from fossil fuels. According to the USEPA's greenhouse gas emissions calculator, the desalination plant would emit between 3.1 and 4.6 metric tons of carbon dioxide per million gallons of water, compared with 0.176 and 2.5 metric tons of carbon dioxide for conventional drinking water treatment plants. If the plant were to operate at full capacity of 7.5 mgd for a full year, it would emit up to 12593 metric tons of carbon dioxide, equivalent to the annual carbon dioxide emissions of 12,600 passenger vehicles[5].
E. Ecological Impact and Water Quality
Haverstraw Bay, where the proposed plant will be located, is an ecologically sensitive area. Constructing a desalination plant would very likely disrupt the local ecology and could harm already declining populations of fish species. Wastewater from the plant would contain heavy metals and toxic chemicals and be highly saline. United Water would send the waste product to a nearby wastewater treatment plant, creating an extra burden for the plant that may increase the toxicity of the wastewater effluent[1].
The resultant water quality of desalinated Hudson River water has been called into question. Up until the 1970s, General Electric dumped polychlorinated biphenyls (PCBs) into the Hudson River. PCBs are persistent and non-reactive, creating a problem for clean-up. Because of PCBs, local authorities have placed a limit on the amount of fish from the river that can be safely consumed. The source water may also be contaminated by the now defunct Haverstraw Landfill. Finally, the source water risks radiation contamination, namely from tritium, from the Indian Point Nuclear Power Plant [6]. Reverse osmosis produces high quality water, but some of these contaminants may not be filtered out entirely. A study by the University of Nevada revealed that high concentrations of PCBs are not well removed by desalination. Many radioactive elements are effectively removed by desalination [7], however, tritium may not be one of them[6].
IV. Alternatives
1. Conservation
Single family residential homes account for 46.2% of Rockland County's total water demand. Encouraging water conservation and installing water efficient devices in the home could greatly reduce domestic water consumption. Rockland County has 63,474 single family homes[2]. Low-flow toilets reduce water usage from 5 gallons per flush to 1.6 gallons per flush, and fixing leaky toilets can save up to 200 gallons of water per day[8]. Assuming 5 flushes per day, a three-person household could reduce water consumption from 75 gallons per day down to 24 gallons per day, saving 51 gallons per day per household, totaling 3.2 million gallons per day for all of Rockland County. This is, of course, assuming 100% conversion to low-flow toilets, which is highly unlikely in a limited time frame. Even a 15% increase in low flow toilets would save 486,000 gallons of water per day. Water conserving washing machines can reduce water usage from up to 54 gallons per load down to less than 27 gallons per load[8]. Assuming one load of laundry per household per day, 100% conversion to water conserving machines would reduce water consumption by 1.7 million gallons per day; 15% conversion would reduce demand by 260,000 gallons per day. Low flow showerheads reduce water usage from 2.5gpm to 2gpm[8]. Assuming a 10 minute shower, daily per person low flow showerheads could save a maximum of 634,740 gallons per day, and 95,211 gallons per day with 15% of showerheads replaced with low flow showerheads. Converting all of Rockland County residents' toilets, showerheads, and washing machines to water efficient devices has the potential to save 5.5 million gallons per day, more than double the capacity of the proposed desalination plant in its first phase. The more obtainable estimate of 15% conversion would result in savings of 841,211 gallons per day. The numbers indicate that it is worthwhile to invest in water-conserving appliances; retrofitting a majority of Rockland homes with such devices and implementing them in new developments could lead to substantial water savings in the long run.
Water efficient appliances not only have the potential to dramatically decrease residential water demand, they also present an opportunity for consumers to save money. According to a water conservation study in California, water efficient showerheads could save residents over $1000 per acre-foot. Efficient washing machines and dishwashers could save $74 and $14 per acre-foot, respectively[9]. These appliances are all relatively cheap and easy to access and install. Water saving toilets can be purchased for under $200; efficient washing machines can be found for under $500, and low-flow showerheads come well below $50. Although residential water conservation has the potential to significantly contribute to closing the water supply and demand deficit in Rockland County, it is not an option that United Water can propose, as the company cannot enforce water conservation or the installation of energy efficient devices[1]. United Water can only increase the supply; it is up to consumers to reduce demand, and to government to create incentives for consumers.
2. Fixing Leaky Infrastructure
United Water may not have the authority to enforce conservation measures, but the company can address leaky infrastructure to save water. The company reported 4.17 mgd in water losses in 2007, 2.13 mgd of which it considers "unavoidable". This leaves a little more than 2 mgd that could be saved by repairing infrastructure[1]. This would meet a significant amount of the projected deficit, and is close to the planned output of the desalination plant in its first phase. No studies have been carried out estimating the cost of fixing leaky infrastructure in Rockland County in particular. A recent study of conservation potential for urban California estimated up to 80% water savings from fixing leaks in the system, at a cost of less than $200 per acre-foot, or roughly $600 per million gallons. Half of all leaks could be saved for half this amount per acre-foot[9]. This solution is much cheaper than any new water infrastructure, however in Rockland County it alone may not produce a sufficient increase in water supply.
3. Stormwater Management
Urbanization of Rockland County has led to increased storm runoff and decreased infiltration into groundwater. Undeveloped land can infiltrate up to 50% of precipitation; on developed land this is reduced to 30% or less[10]. Rockland County has many options for stormwater management. Rainwater can either be collected directly, or the ground's infiltration capability can be improved to increase recharge to groundwater.
A. Land Use Planning
Rockland County has developed substantially in the post-World War II era, shifting from primarily rural and agricultural to increasingly suburban. This land-use and resultant land-cover change has impacted the region's hydrology substantially. Urbanization clears vegetation and increases impermeable groundcover, both of which increase surface runoff and decrease infiltration[10]. Rockland County could increase infiltration by adopting low impact development (LID). Green space conservation refers to minimizing the amount of land area used in a development, thereby preserving the most green space possible. This minimizes infiltration losses, and provides the additional benefits of wildlife habitat and recreational space. Where pavement is necessary, permeable pavement materials could be used to increase infiltration[11]. In recent decades, groundwater pumping in Rockland County has been somewhat restricted; overall, water tables have not declined as a result. Increasing infiltration would allow United Water to pump more groundwater without lowering the water table.
B. Blue Roofs
Blue roofs are an increasingly popular option for stormwater management. A blue roof is non-vegetated and designed to store water, typically rainwater, and either slowly release it to prevent combined sewer overflow or store it for use or groundwater recharge. A blue roof contains small openings (weirs) inside the inlets of roof drains that collect rainwater. Blue roofs are much more cost-effective than green roofs; blue roofs range from $1/square foot to 4$/square foot, compared to 18$/square foot to 25$/square foot for a green roof. Additionally, maintenance cost for a blue roof is comparable to that of a conventional roof. No studies on the potential of rainwater harvesting have been carried out for Rockland County, however an Australian study found a 26% reduction potential in demand for households that implemented rainwater collection, or a harvesting of 826 ML per year (220 million gallons)[12]. The study took place in Werribee, a suburb of Melbourne, Australia, which received roughly 25.5 inches of rainfall per year. The potential for rainwater collection in Rockland County is perhaps greater since it experiences on average 48.7 inches of rainfall and 30 inches of snow per year[1].
4. Water Reuse
A. Greywater Reuse
Greywater reuse has the potential to dramatically reduce domestic water demand. Greywater, also known as sullage, is defined as water from bathroom sinks, showers, and baths. Greywater can also include water from washing machines, kitchen sinks, and dishwashers, however this is often excluded due to nutrient loads. Water from toilets that has come into contact with human waste is always excluded from greywater, and is referred to as blackwater[13]. Greywater comprises between 50 and 80 percent of residential water use, or 25-40 gallons per person per day. Greywater is typically reused for toilet flushing and irrigation. Toilets account for 26% of household water use, thus greywater reuse for toilet flushing alone could reduce domestic water demand by this amount[14].
B. Wastewater Reuse
Rockland County generates 20 million gallons of wastewater effluent per day, more than twice the maximum capacity of the proposed desalination plant. United Water's environmental impact statement acknowledges the possibility of wastewater reuse, and estimates that roughly 10.5 million gallons per day could feasibly produce the required 7.5 million gallons per day. The statement also recognizes the fact that wastewater reuse would not have the same adverse impacts on aquatic ecosystems in the Hudson River. United Water estimates that capital costs for wastewater reuse at 302.6 to 325.9 million dollars, with annual operating costs of $7.5 million. By comparison, they estimate that the desalination plant will cost 139.2 to 189.3 million dollars to construct, with operating costs of $5.6 million per year[2]. By United Water's estimates, wastewater reuse is an economically irresponsible alternative. The estimated cost of wastewater reuse is disputed by some engineers, with estimates of capital costs as low as $97 million, substantially lower than the estimated capital costs of the desalination plant[15].
5. Watershed Management
A drought, or a water shortage, is the result of either insufficient supply or too high demand. Managing a watershed effectively requires minimizing demand, as previously discussed, as well as optimizing supply. When faced with a water shortage, it is tempting and somewhat intuitive to search for an additional water source to meet demand. This is however not always necessary nor the most cost-effective way to address a water shortage. Water supply, in some instances, can be increased dramatically simply by eliminating water losses within the watershed. This can sometimes be a complicated process, since watershed boundaries can transcend political boundaries. Cooperation between counties and even states is therefore critical. In the case of Rockland County, supply could be dramatically increased by minimizing unnecessary losses.
A. Groundwater Supply
In February 2011, the United States Geological Survey (USGS) released a comprehensive assessment of Rockland County's groundwater resources. This study reviewed groundwater withdrawals and recharges since 1989 across the large bedrock aquifer that underlies much of the region. The findings suggest no downward trend in groundwater levels across the aquifer; the author even suggest increased groundwater pumping as a potential additional resource for municipal water. Although the study did not indicate the additional quantity of groundwater that could be sustainably pumped, it found groundwater recharge to be 15-25 cm throughout the aquifer annually[10]. Increasing the amount of green space in Rockland County could increase these numbers, as discussed previously.
B. Lake DeForest
United Water New York (UWNY) releases a considerable amount water from Lake DeForest into New Jersey. The New York Department of Environmental Conservation permits a release of 9.75 million gallons per day, 2 million of which are allocated for the Nyack Water Company; the remaining 7.75 million go to New Jersey. During June and July of 2010, United Water released a total of 9.7 million gallons per day from Lake DeForest, an excess of 1.95 million gallons per day. According to Dr. Daniel M. Miller of the Water Supply Bureau of the Rockland County Department of Health, United Water New Jersey was receiving on average an excess of the required supply of 19.25 million gallons per day from 1965 to 2008[16].
The premise for requiring UWNY to release substantial amounts of water into New Jersey is questionable. The original decision authorizing the construction of the Lake DeForest reservoir stated that it was to be operated exclusively for the benefit of Rockland County residents; any benefit to New Jersey, namely the regulated flow of the Hackensack River, was entirely incidental. In recent years, the New Jersey Department of Environmental Protection required New Jersey's Orodell reservoir to release a minimum of 8.34 million gallons per day into the Hackensack River, feeding into the Atlantic Ocean. United Water New Jersey has at times exceeded the release by 1.35 million gallons per day. The ultimate result of the releases from the reservoir is an increase of 9 million gallons per day in the Hackensack River's median flow when compared with historical records[16]. Current practices require New Jersey to release an unnecessary and excessive amount of water in to the Hackensack River, and ultimately into the Atlantic Ocean, and requires Rockland County to provide this water. Putting a halt to this practice would solve Rockland's projected water shortage by itself.
C. Lake Tappan
An additional water supply for Rockland County comes from riparian rights to a portion of the water from the Hackensack River. When the Hackensack Water Company built a dam and created Lake Tappan, it flooded the lands of New York State. A portion of the lake and its entire watershed reside within Rockland County, giving Rockland County riparian rights to a portion of the water of Lake Tappan. Although Rockland County has never made plans to exercise riparian rights, these rights have been acknowledged as far back as 1965. The then-president of the Hackensack Water Company testified that water could be feasibly pumped from Lake Tappan to Lake DeForest, and the company intended to do so. The attorney general of the town of Orangetown also argued that Rockland County should have access to half of the increased yield from the river, about 5 million gallons per day[16]. This would amount to over half of the capacity of the proposed desalination plant in its final stage.
V.Conclusion: Soft Water Management
Soft water management refers to a demand-side, integrative approach to water management. Current practices emphasize a supply-side approach, looking towards large infrastructure and centralized water resources. This can be seen in the Haverstraw Water Project. When faced with a potential water deficit, Rockland County and United Water looked sought out a new water source, and considered expensive infrastructure. A soft water approach would look at reducing demand; conservation, on a large enough scale, in itself has the potential to solve Rockland's water crisis. If residents are willing, they could save a considerable amount of water with greywater reuse and water-efficient appliances. An integrative approach is necessary to meet future demand. This includes proper watershed management that addresses leaks and unnecessary discharges and takes advantage of riparian rights. Sustainable urban planning should consider rainwater collection and design that allows for increased infiltration would minimize losses from surface runoff.
Notes and references[edit | edit source]
Not Worth Its Salt. 2010. MS, Food and Water Watch, Washington D.C. January 2010. Accessed December 8, 2013. Technical paper. January 2012. Accessed December 8, 2013. haverstrawwatersupplyproject.org.
"The Haverstraw Water Supply Project: Ensuring the Future of Rockland's Water." Speech, NAWC, Orlando, October 13, 2009. Accessed December 8, 2013. http://www.sustainablerockland.org/wp-content/uploads/United-Water-PowerPoint-Orlando-Florida-10-13-2009.pdf.
"What Is Reverse Osmosis." Water Quality Association. Accessed December 07, 2013. http://web.archive.org/web/20140628022812/http://www.wqa.org/sitelogic.cfm?ID = 872.
"Greenhouse Gas Equivalencies Calculator." EPA. Accessed December 06, 2013. http://www.epa.gov/cleanenergy/energy-resources/calculator.html.
Connor, Liliana. "Treatment Method Won't Eliminate Carcinogens." Preserve Ramapo. April 10, 2013. Accessed December 08, 2013. http://www.preserveramapo.org/treatment_method_wont eliminate carcinogens.htm.
Tomoszewska, Barbara, and Michal Bodzek. "The Removal of Radionuclides during Desalination of Geothermal Waters Containing Boron Using the BWRO System." January 15, 2013. Accessed December 08, 2013.
http://www.sciencedirect.com/science/article/pii/S001191641200584X. "EPA WaterSense| Water Efficiency, Water Conservation & Water Savings." EPA. Accessed December 08, 2013. http://www.epa.gov/watersense/.
Gleick, Peter H., Dana Haasz, Veena Srinivasan, Gary Wolff, Katherine K. Cuching, and Amardip Mann. "Waste Not Want Not: The Potential for Urban Water Conservation in California." The Pacific Institure. November 2003. Accessed December 8, 2013.
Heisig, Paul M. Water Resources of Rockland County, New York, 2005-07, with Emphasis on Newark Basin Bedrock Aquifer. Report. 2010.
"Low Impact Development." Bureau of Water. Accessed December 08, 2013. http://web.archive.org/web/20131231200901/https://www.scdhec.gov/environment/water/swater/LIDs.htm. Werribee Plains Urban Water Management-WaterCycle and Economic Modelling. Report. July 7, 2008. Accessed December 8, 2013. Werribee Plains Urban Water Management-WaterCycle and Economic modelling.
"Gray Water Use in New York." Eco Brooklyn Inc. Accessed December 08, 2013. http://web.archive.org/web/20190709202452/https://ecobrooklyn.com/gray-water-york/.
Research of Graywater for Use in Residential Applications. Report. August 12, 2010. Accessed December 8, 2013. http://www.tampabaywater.org/documents/conservation/GraywaterUpdate8_12_2010_final.pdf. Feminella, Richard C. "From Richard C. Feminella, P.E." Rockland Water Coalition RSS. Accessed December 08, 2013. http://www.sustainablerockland.org/from-richard-c-feminella-p-e/.
Dillon, Bob. "United Water's Argument For Desal Plant Leaks Like A Sieve." Rockland Water Coalition RSS. June 30, 2011. Accessed December 08, 2013. http://www.sustainablerockland.org/united-water's-argument-for-desal-plant-leaks-like-a-sieve/.