Niagara Power Project FERC No. 2216
DETERMINE IF PROJECT OPERATIONS IMPACT AIR QUALITY
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Prepared for: New York Power Authority
Prepared by: URS Corporation
August 2005
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Copyright © 2005 New York Power Authority
EXECUTIVE SUMMARY
In preparation for the relicensing of the Niagara Power Project (Project), the New York Power Authority (NYPA) is developing information in regard to all aspects of the Project and its potential effect upon its environment. This report documents information related to the determination of whether Project operations impact air quality in the surrounding area.
One of the major components of the Project is the approximately 1,900-acre Lewiston Reservoir, a pumped-storage facility used to store water from the Niagara River for the purpose of power production during peak-use periods. Given the known presence of contaminants in the Niagara River (the source of Lewiston Reservoir water), it has been asked whether the operation of the reservoir might contribute to the volatilization of contaminants from the sediment or water into the atmosphere. Also of concern is the magnitude and influence of heat emissions from Project operations and facilities, including both the Robert Moses Niagara Power Plant (RMNPP) and the Lewiston Pump Generating Plant (LPGP). To address these concerns, the objectives for this study are to (1) evaluate the influence of emissions, including possible volatilization of contaminants from sediment or surface water in the Lewiston Reservoir, and (2) determine the temperature and volume of heat emissions from the RMNPP and LPGP.
Two potential sources of emission from the reservoir were evaluated. The first was the water in the reservoir. Surface water samples collected from the Lewiston Reservoir showed no detectable concentrations of organic compounds, thus eliminating this as an emissions source. The second source evaluated was reservoir sediment that is sometimes exposed during periods of low water in the reservoir. Analysis of reservoir sediment showed the presence of both volatile and semivolatile organic compounds. The only detected volatile compounds were acetone and 2-butanone. Fourteen semivolatile compounds were detected, all of which are polynuclear aromatic hydrocarbon (PAH) compounds. Using equations based on the properties of the sediment and the specific compounds detected, a flux rate (in lb/hr-ft2) was calculated for emissions from the sediment. The compounds with the highest rates of emission were acetone and naphthalene, although other compounds were found. The flux rate for each compound was then multiplied by the area of sediment exposure to determine to the actual emission rate (in lb/hr) from that area.
The area of sediment exposed for emissions varies with the level of water in the reservoir. It is only when the water level in the reservoir reaches El. 631 feet that sediment begins to be exposed. The area exposed ranges from approximately 4 acres at El. 631 feet, to 552 acres at El. 620 feet, the normal low point. The water level in the reservoir is usually at lower elevations toward the end of the week. The total duration of sediment exposure averages approximately 12 hours per week, although this varies due to the seasonal change in operation. Based on 14 years of operating data, the time-weighted average area of exposed sediment was calculated to be 4.5 acres. On average, no portion of the reservoir bottom is exposed more than approximately 7% of the year. Multiplying the flux rate for each compound of concern by the time-weighted average exposed area of 4.5 acres, a total average emission rate of 0.0031 lb/hr was calculated for all compounds.
Using the calculated emission rates and the United States Environmental Protection Agency (USEPA) SCREEN3 dispersion model, ambient air concentrations were calculated for both short-term and long-term scenarios, and then compared to the corresponding New York State Department of Environmental Conservation (NYSDEC) guideline concentrations. Even based on the screening level concentrations, which are conservative, all contaminant concentrations in ambient air are estimated to be well below NYSDEC guideline values. Impacts upon air quality from the reservoir are therefore concluded to be minimal and acceptable.
Heat emissions from the facility also have a limited impact, if any, on the surrounding air quality. The generators, which are the major source of heat at the facility, are water-cooled, using water that is taken from and ultimately returned to the river, thus transferring facility-generated heat to the river as opposed to the atmosphere. The flowrate of the cooling water as compared to the flow of water through the turbines is so low that there is no appreciable rise in the temperature of the water in the tailrace. No heat generated at the facility is of high enough quality for reuse.
The New York Power Authority (NYPA) is engaged in the relicensing of the Niagara Power Project (Project or NPP) in Lewiston, Niagara County, New York. The present operating license of the plant expires in August 2007. As part of its preparation for the relicensing of the Project, NYPA is developing information related to the ecological, engineering, recreational, cultural, and socioeconomic aspects of the Project. This report documents information related to the determination of whether Project operations impact air quality in the surrounding area.
The 1,880-MW (firm capacity) Niagara Power Project is one of the largest non-federal hydroelectric facilities in North America. The Project was licensed to the Power Authority of the State of New York (now the New York Power Authority) in 1957. Construction of the Project began in 1958, and first electricity was produced in 1961.
The Project has several components. Twin intakes are located approximately 2.6 miles above Niagara Falls. Water entering these intakes is routed around the Falls via two large low-head conduits to a 1.8-billion-gallon forebay, lying on an east-west axis about 4 miles downstream of the Falls. The forebay is located on the east bank of the Niagara River. At the west end of the forebay, between the forebay itself and the river, is the Robert Moses Niagara Power Plant (RMNPP), NYPA’s main generating plant at Niagara. This plant has 13 turbines that generate electricity from water stored in the forebay. Head is approximately 300 feet. At the east end of the forebay is the Lewiston Pump Generating Plant (LPGP). Under non-peak-usage conditions (i.e., at night and on weekends), water is pumped from the forebay via the plant’s 12 pumps into the 22-billion-gallon Lewiston Reservoir, which lies east of the plant. During peak usage conditions (i.e., daytime Monday through Friday), the pumps are reversed for use as generators, and water is allowed to flow back through the plant, producing electricity. The forebay therefore serves as headwater for the RMNPP and tailwater from the LPGP. South of the forebay is a switchyard, which serves as the electrical interface between the Project and its service area.
Operation of the NPP can result in water level fluctuations in the Lewiston Reservoir of 8-18 feet per day, and as much as 36 feet per week.
Given the known presence of various contaminants in the Niagara River (the source of Lewiston Reservoir water), it has been asked whether the operation of the reservoir may contribute to the volatilization of contaminants from sediment or water into the atmosphere. Of specific concern is the air transport of contaminants to the Tuscarora Nation, immediately adjacent to the reservoir. Also of concern is the magnitude and influence of heat emissions from the operation of the Project.
The objectives of this study are to (1) evaluate the influence of emissions, including possible volatilization of contaminants from sediment or surface water in the Lewiston Reservoir, and (2) determine the temperature and volume of heat emissions from the Robert Moses Niagara Power Plant and the Lewiston Pump Generating Plant.
The investigation area includes the RMNPP, the LPGP, the Lewiston Reservoir, and the areas immediately surrounding these facilities.
The RMNPP, located at the western end of the forebay, contains 13 individually controlled generating units in a 1,100-foot-long concrete structure located at the base of the gorge wall. Average head is approximately 300 feet. Water from the forebay discharges from each unit through an individual draft tube into a short tailrace channel, which leads directly to the lower Niagara River.
The four-lane Lewiston Road and the four-lane Robert Moses State Parkway traverse the top of the plant. The Power Vista (a visitors center overlooking the Niagara gorge) is on the plant’s south abutment.
The LPGP is located at the eastern end of the forebay. Its purpose is to pump water from the forebay into the Lewiston Reservoir during periods of low electricity demand, and to generate electricity from release of this stored water during periods of peak demand. Each of the 12 generating units consists of a Francis-type pump-turbine connected to a motor-generator unit. Each electrical unit is rated at 37,500 horsepower (hp) as a motor and 20 megawatts (MW) as a generator. The lower deck of the LPGP serves as a bridge that carries Military Road and the Niagara Expressway (I-190) over the forebay.
The approximately 1,900-acre Lewiston Reservoir, which stores water for use as headwater by the LPGP, is impounded by a 6.5-mile-long rock-filled dike (with impervious clay core) anchored at each end of a 1,000-foot-long concrete plant intake structure. The entire shoreline of the Lewiston Reservoir is lined with boulder-size riprap. At its maximum surface elevation, water in the reservoir is about 42 feet deep, and at its minimum, just over 3 feet. The gross storage capacity of the reservoir is 24 billion gallons, with a usable storage capacity of 22.6 billion gallons.
The Niagara Power Project and the Lewiston Reservoir operate on a weekly cycle. On Monday morning, the reservoir is at its highest water level and typically at its lowest on Thursday or Friday evening. Each weekday, water is taken from storage during the daytime peak energy demand periods for power generation. Consequently, the reservoir water level decreases. Then each weekday night (during non-peak energy demand), the reservoir is partially refilled. On the weekend, the reservoir is completely refilled. Daily drawdown is normally 3-18 feet and weekly drawdown 11-36 feet, depending on the season and river flow. Since the storage in the Lewiston Reservoir is used to reallocate Niagara River flow for power generation during peak demand periods, weekly drawdowns are typically greater during the tourist season (21-36 feet) than the non-tourist season (11-30 feet). Weekly drawdowns are also greater during low-flow periods than high-flow periods, as more water is rescheduled to generate electricity during peak demand periods. Portions of the reservoir bottom are sometimes exposed due to drawdown of the water, especially towards the end of the week.
The estimate of potential emissions from the Lewiston Reservoir described in Section 3.0 is based on data collected specifically for this study, as well as on data collected for other studies related to relicensing. This section identifies the source of the analytical data used, and, for data collected specifically for this study, presents the methods used for collecting and analyzing the samples.
The most exact method to evaluate air emissions is to measure the emissions directly from the source; e.g., to collect and analyze samples directly from a discharge stack. However, analysis of air samples at and around the reservoir would be difficult to collect and would produce data of limited usefulness. Collection of samples would have to be coordinated with periods when the sediment is exposed, which are difficult to predict. Emissions from the reservoir are expected to be of low and highly variable concentration, and therefore difficult to quantify with air samples. It was determined that the best method to evaluate impact would be to estimate (using conservative assumptions) potential emissions based on measured concentrations of detected analytes in the water and sediment.
The surface water sample analytical results used for this study were collected as part of the groundwater investigation being conducted by NYPA as part of its relicensing effort (URS Corporation 2004, in prep.).
As part of the groundwater investigation, two surface water sampling events were conducted in 2003. The first was conducted in September-October 2003, and the second in November-December 2003. The goal for each sampling event was the collection of surface water samples from 11 locations in and around the NPP (along with the collection of groundwater samples from several groundwater monitoring locations). Of interest to this study are the two surface water sample locations in the Lewiston Reservoir, namely, SW03-006 and SW03-011, the former located at the western and the latter at the eastern end of the reservoir (Figure 2.2-1). Each was sampled in October and November 2003.
Surface water samples were collected by direct submersion of the sample bottles and capping underwater. Following sample collection, the sample bottles were placed in coolers, iced, and transported via courier to Severn Trent Laboratories of Buffalo, New York, for analysis. The surface water samples were analyzed for an extensive list of organic, inorganic, and biological parameters.
Analytical results from surface water samples collected at two sites in the Lewiston Reservoir in 2003 are presented on Table 2.2-1. Results for organic compounds reveal that both VOCs and SVOCs were below the reporting limit (i.e., were non-detectable) at both surface water sample locations during the two sampling events.
In October 2002, five sediment samples (RES-SED-05 through RES-SED-09) were collected as part of a relicensing study to determine the extent and quality of sediment in the Lewiston Reservoir (ESI 2003). These samples were analyzed for the contaminants of concern being routinely sampled as part of the long-term Niagara River Toxics Management Plan (NRTMP). Since volatile organic compounds (VOCs) are the compounds normally evaluated in air emissions studies, and since only one VOC, namely, tetrachloroethylene (PCE), was targeted by the NRTMP, the ESI 2003 results were not sufficient for the present study.
Because the sediment samples collected in 2002 did not include analysis for VOCs, five additional sediment samples were collected and analyzed for the full USEPA target compound list (TCL), which includes a number of both volatile and semivolatile organic compounds (SVOCs). Table 2.4-1 shows a complete list of these organic parameters. Analysis was also carried out for other, geotechnical parameters used in the emission calculations.
Sediment sampling locations RES-SED-13 through RES-SED-17 are shown in Figure 2.2-1. Locations were selected according to the following criteria: (1) presence of sufficient volume of sediment for sampling, (2) known exposure of the sampled area during low-water periods, and (3) spatial distribution of sampling locations across the reservoir. For consistency with the number of samples collected in ESI 2003, it was decided to collect five samples.
Using GIS, a figure showing sediment thickness within the reservoir was overlaid with a figure showing the areas of the reservoir exposed during low water elevations (see Figure 2.2-1). Sediment thickness was evaluated in the ESI 2003 report, based on a 2001 bathymetric survey coupled with construction elevations for the reservoir. The area of sediment exposure was determined at a water elevation of El. 620 feet, the operational low level for the reservoir. As shown in Figure 2.2-1, the areas exposed during operation are generally not areas where there has been an accumulation of sediment.
Due to the relatively few areas that were both periodically exposed and projected to contain enough sediment for sample collection, it was decided that only four of the samples could reasonably be collected from the exposed areas. The fifth sample (RES-SED-17) was collected from a location of sedimentation, but one not exposed during low-water periods. The fifth sample also will indicate whether there is any difference in sediment from the exposed and non-exposed areas.
Although the intent of the sampling effort was to collect samples of sediment that are exposed during low-water periods, the samples were actually collected when reservoir levels were near their highest. The reason for this was that boat access was the only reasonable way to reach the sampling area, and high water was required for such access.
Sediment samples were analyzed for both chemical and physical parameters, including (1) USEPA TCL VOCs, (2) TCL SVOCs, (3) total porosity, (4) total organic carbon, (5) moisture content, and (6) grain size. All sediment samples were collected on October 30, 2003, from a boat. Using latitude and longitude information for the proposed sampling locations and a Global Positioning System, the boat operator was able to anchor the boat within approximately 10 feet of each proposed sampling location. Because the purpose of this study is to evaluate air emissions, and since emissions occur from the surface of the sediment layer, all sediment samples were collected with a Ponar dredge from the top 6 inches (or less) of sediment.
Table 2.4.3-1 summarizes detected analytical results for sediment VOCs and SVOCs, and gives the maximum value detected for each compound. For comparison, results from the samples collected in 2002 are also shown on this table.
Analysis of the five samples (RES-SED-13 through RES-SED-17) for VOCs showed the presence of only two, namely, acetone and methyl ethyl ketone (also called 2-butanone). While the concentration of these two compounds was relatively consistent among the five samples, the highest concentrations of both were found in sample RES-SED-17, collected from the area that remains constantly submerged.
With regard to SVOCs, fourteen SVOC compounds were detected in the sediment, all of which are polynuclear aromatic hydrocarbon (PAH) compounds. These are generally compounds that structurally contain two or more molecular ring structures, that have higher molecular weights, and that have lower vapor pressures than other SVOC compounds. Comparison of SVOC results from the 2003 sediment samples to those previously analyzed (RES-SED-05 through RES-SED-09), showed that most of the same parameters were detected, and at similar concentrations. Therefore, as a conservative assumption (from the perspective of environmental effect), the maximum detected value from the samples analyzed for ESI 2003 or the samples analyzed for this study was used as the concentration of that particular contaminant in the calculations presented in Section 3.0.
Results for the geotechnical parameters analyzed on the 2003 samples are presented in Appendix A-2. In general, the results of these analyses are consistent with samples that have been collected previously.
Quality control (QC) samples employed during the sediment sampling program included a field duplicate, matrix spike/matrix spike duplicate (MS/MSD), and a sampling equipment rinse blank sample. A Data Usability Summary Report for the 2003 sampling event is presented in Appendix A, along with the validated analytical results. Of importance to note is that while both acetone and 2-butanone are common laboratory contaminants, there was no evidence of that in the data package, and thus their presence in the sediment cannot be discounted.
Surface Water Sample Analytical Results for the Lewiston Reservoir, October and November 2003