ML15062A030

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Work Plan for Completing a Once Through Cooling Water Study for Total Dissolved Solids, Chlorides, and Sulfates
ML15062A030
Person / Time
Site: Comanche Peak  Luminant icon.png
Issue date: 02/25/2015
From:
CH2M Hill
To:
Luminant Generation Co, Office of Nuclear Reactor Regulation
Shared Package
ML15062A029 List:
References
Download: ML15062A030 (11)
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Text

Work Plan for Completing a Once Through Cooling Water Study for Total Dissolved Solids, Chlorides, and Sulfates Luminant Comanche Peak Nuclear Power Plant Segment 1229 of the Brazos River Basin Somervell County, Texas Prepared for Luminant Generation Company LLC TPDES Permit No. WQ0001854000 Dallas, Texas February 2015 CH2MHILL.

Prepared by 12750 Merit Drive Suite 1100 Dallas, TX 75251

Acronym s and Abbreviations ................................................................................................................................ ii S Introduction ............................................................................................................................................ 1-1 1.1 Background ......................................................................................................................................... 1-1 1.2 Project O bjectives .............................................................................................................................. 1-1 1.3 Project Scope ...................................................................................................................................... 1-2 1.4 Project Team ...................................................................................................................................... 1-2 2 Site D escription and Regulatory Status .................................................................................................. 2-1 2.1 Site D escription .................................................................................................................................. 2-1 2.2 Regulatory Status ............................................................................................................................... 2-1 3 Investigation Procedures ........................................................................................................................ 3-1 3.1 Sam pling Strategy ............................................................................................................................... 3-1 3.2 D eterm ination of Sam pling Locations ........................................................................................... 3-1 3.2.1 Proposed Sam pling ............................................................................................................. 3-1 3.2.2 Proposed Sam pling Schedule ............................................................................................ 3-1 4 Sam pling Conditions .............................................................................................................................. 4-1 4.1 Am bient and Background Conditions ............................................................................................ 4-1 4.2 O perating Conditions ........................................................................................................................ 4-1 4.3 Sam pling Points and Log Sheets ..................................................................................................... 4-1 5 D ata Analysis .......................................................................................................................................... 5-1 5.1 Statistical Analyses ............................................................................................................................. 5-1 5.1.1 Statistical Approach / D ata Collection ........................................................................... 5-1 5.1.2 Statistical Test Methods ..................................................................................................... 5-1 Tables 3.1 Sam pling Schedule ...................................................................................................................................................................... 3-1 4.1 Am bient / Background Conditions Log Sheet ...................................................................................................................... 4-2 4.2 O perating Conditions Log Sheet .............................................................................................................................................. 4-2 Figures 1.1 Location M ap ............................................................................................................................................................................... 1-2 2 .1 F acility M ap .................................................................................................................................................................................. 2 -2 WTOZ21O151O1QOFW

°C degrees Celsius CH2M HILL CH2M HILL Engineers, Inc.

DHL DHL Analytical Services, Inc.

EPA U.S. Environmental Protection Agency Luminant Luminant Generation Company LLC mg/i, milligrams per liter MGD million gallons per day ml, Milliliter NPP Nuclear Power Plant OTCW once-through cooling water TAC Texas Administrative Code TCEQ Texas Commission on Environmental Quality TDS Total Dissolved Solids TPDES Texas Pollutant Discharge Elimination System VWrr21015102 DFW

1.1 Background Luminant Generation Company LLC (Luminant) has contracted CH2M HILL Engineers, Inc.

(CH2M HILL) to provide consulting services for completing a once-through cooling water study at the Comanche Peak Nuclear Power Plant (NPP). Chemical analysis will be conducted by an independent laboratory. This Once-Through Cooling Water Study Plan (Study Plan) was prepared for use during investigation of Total Dissolved Solids (TDS), Chlorides, and Sulfates concentrations of the cooling water at the facility. This Study Plan specifies sampling points, procedures, data collection, and quality assurance methods that will be used during sampling activities to assure quality data are obtained.

The Comanche Peak NPP is located in Somervell County in north central Texas approximately 4.5 miles northwest of the City of Glen Rose, Texas. The location of the Comanche Peak NPP is shown on Figure 1.1.

The circulating water streams that are the focus of this study are obtained from Squaw Creek Reservoir, which is adjacent to the power plant.

1.2 Project Objectives Texas Administrative Code 30 TAC 307.8(d) specifies that water quality-based effluent limits will not be required when a discharge of once-through cooling water (OTCV) does not "measurably alter" the intake concentration. However, to establish whether or not a discharge of OTCW is measurably altered, Procedures to Implement the Texas Surface WaterQua/io,Standardsl requires the statistical analysis of paired samples to determine if there is a significant difference between the intake and discharge concentrations at the 95%

confidence level.

The purpose of this study is to determine if there is a statistically significant difference between the TDS, Chloride, and Sulfate concentrations in the circulating water intake and the effluent that would require water quality-based effluent limits. This Study Plan will focus on methods and procedures that allow accurate quantification of the dissolved minerals concentrations in the cooling water before and after passing through the power plant. It will specify the number, type, and locations of samples, along with details of the proper sampling techniques and analytical methods. This document will be used by field and laboratory personnel as a guideline for conducting the sampling and analysis.

1 Procedures to Implement the Texas Surface Water Quality Standards (RG-194, June 2010).

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INTR~ODUCTION FIGURE 1.1 Location Map 1.3 Project Scope The tasks required to complete the study are as follows:

  • Analyze the water samples for TDS, Chlorides, and Sulfates
  • Evaluate the results of the sampling data using statistical analysis The methods that will be used to complete these tasks are described in the following sections of this Study Plan.

1.4 Project Team The project team consists of Luminant, DHL Analytical Services, Inc. (DHL), and CH2M HILL. Luminant will fund the project, provide input on the study, and collect the samples; DHL will provide the sample kits and perform the analysis; and CH2M HILL will develop the Study Plan, evaluate the data, complete the statistical analysis, and develop the final report.

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2.1 Site Description The Comanche Peak NPP and Squaw Creek Reservoir are located in Somervell County in north central Texas. The power plant consists of two separate generating units, one with a rated capacity of 1084 megawatts and one with a rated capacity of ll21megawatts that operates continuously.

Squaw Creek Reservoir was constructed as a cooling water reservoir to service the power plant. The surface area of the reservoir is approximately 3,275 acres with an average depth of approximately 46 feet. The reservoir discharges occasionally at the southeast end to Squaw Creek thence to the Paluxy River.

The circulating water pumps provide high volumes of cooling water to a large condenser located on each generating unit. Flows from the circulating water system are permitted at 3,168 MGD. Cooling water is pumped from the intake structure located on the north side of the facility, provides cooling for the power plant main condensers, and is discharged back into Squaw Creek Reservoir through the discharge structure located at Outfall 001 on the south side of the facility. Figure 2.1 shows the facility, Squaw Creek Reservoir the cooling water intake, the discharge structure, Outfall 001, and the proposed sampling locations.

2.2 Regulatory Status TPDES Permit No. WQ0001854000 authorizes discharges of wastewater from the Comanche Peak NPP.

The current permit was issued by the Texas Commission on Environmental Quality (TCEQ) on June 26, 2012. The permit authorizes discharge of OTCW, auxiliary cooling water, and previously monitored effluents at Outfall 001.

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SITE DESCRIPTION AND REGULATORY STATUS FIGURE 2.1 Facility Map Intake Sample Point

/

Discharge Sample Point (Outfall 001)

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3.1 Sampling Strategy The sampling strategy is to collect the necessary water samples from the cooling water intake and discharge using proper equipment and procedures to establish the TDS, Chlorides, and Sulfate concentrations of these streams. Samples will be representative of normal operating conditions at the power plant.

3.2 Determination of Sampling Locations Sampling locations as shown on Figure 2.1 were chosen based on a review of physical features at the Comanche NPP.

3.2.1 Proposed Sampling The following samples are proposed for the study:

" At the surface of the reservoir at the circulating water intake structures. At least four depth composites will be collected at the intake to compare to surface samples. Surface sample results will be used in the statistical analysis.

  • At Outfall 001 at the discharge structure to Squaw Creek Reservoir.

Analysis will be performed using EPA approved methods as found in 40 CFR Part 136. Specifically, Standard Method 2540C will be used for TDS with a reporting limit of 50 mg/L, and EPA Method 300 will be used for Chloride and Sulfate analysis with reporting limits of 100 mg/L and 30 mg/L, respectively.

3.2.2 Proposed Sampling Schedule Grab samples will be collected every 10 days for at least ten sample events. Each paired sample will be obtained within a one hour period. The plan is to collect the samples ten days apart unless there is a significant rainfall event in the area. This will provide 10 paired samples, which is the minimum specified in Proceduresto Implement the Texas Surface WaterQua/ity Standards.TDS, Chlorides, and Sulfates concentrations will be measured for the indicated sample points.

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Prior to beginning each sampling round, background data should be collected. This data will include ambient weather conditions, reservoir conditions, and operating conditions of the power plant. This data should be recorded on the appropriate log sheet.

4.1 Ambient and Background Conditions Weather conditions need to be recorded during the sampling activities. For example, actual daily rainfall amounts will be documented. Sampling should be suspended during certain conditions, such as thunderstorms and heavy winds.

Field measurements of pH, temperature, and conductivity should be taken at the time of sample collection.

During the course of the sampling effort, ambient and background conditions data will be recorded on the Ambient/Background Conditions Log Sheet as shown in Table 4.1.

4.2 Operating Conditions Operating conditions to document include items such as generating capacity, and circulating water flow (if available). Operating condition data will be recorded on the Operating Conditions Log Sheet as shown in Table 4.2.

4.3 Sampling Points and Log Sheets The sampling log sheets will include the following information:

" Sample Point ID #

  • Date and time

" Any problems encountered during sampling

" Ambient (weather) conditions

  • Circulating water temperature (inlet and outlet)
  • Specific conductance (Conductivity)

" pH

  • Unit Loads WT0210151012DFW 4-1

SAMPLING CONDITIONS TABLE 4.1 Ambient I Rao TABLE 4.2 Operating Conditions Log Sheet 3odne ultUntLa ntLa 4ieTm ' WM Dat 6

7 8

9 10 WTO210151012DFW'4 4-2

5.1 Statistical Analyses The TCEQ requirement for water quality-based effluent limits of pollutants discharged into OTCW is applicable unless there is "no measurable increase" in the pollutant concentration of the effluent as compared to the intake water. The term "no measurable increase" is statistically defined; therefore, it must be demonstrated by statistical analysis of the sampling data that there is not a statistically significant difference at the 95% confidence level between the concentrations of TDS, Chlorides, and Sulfates in the intake and effluent. Only then can the condition for exclusion of OTC\W from water quality-based permit limits be satisfied.

5.1.1 Statistical Approach I Data Collection A statistical analysis of the data will be done to determine if there is "no measurable increase" in the TDS, Chloride, and Sulfate concentrations across the OTCW system of the Comanche Peak NPP.

  • Ten paired samples will be collected which meets the minimum number of paired samples of 10 as specified by TCEQ.
  • Paired samples shall be collected no more than one hour apart.
  • Paired data (intake and effluent sample concentrations) of TDS, Chlorides, and Sulfates will be used to conduct the statistical analysis.

5.1.2 Statistical Test Methods The lognormal distribution is usually chosen for environmental data as described in the EPA Technical Support 2

Documentfor WaterQuality Based Toxics Control.

The two-tailed Student's t-test will be done on the log mean and log standard deviation of each data set at the 95

% confidence level to check for significant differences between the effluent data and the intake water data.

If the results show the calculated t-statistic (t-Stat) is less than the critical t-statistic (t-Critical two-tail), then there is no significant difference between the concentrations of TDS, Chlorides, and Sulfates in the intake and effluent. However, if the t-Stat is greater than the t-Critical two-tail then there is a statistically significant difference between the intake and the effluent stream concentrations.

Data outliers for each data set will be evaluated using statistical test methods described by the EPA (EPA, 1992). In this method a calculated test statistic is compared to a critical value. The datum is an outlier if the calculated test statistic is greater than the critical value. Any data that are legitimate statistical outliers will be excluded from the data set.

2 Technical Support Document for Water Qualtry Based Toxics Control (FP.\ 505-2-90,-001, March 1991).

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