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HomeMy WebLinkAboutNC0000272_Analysis of Color Concentrations 3-4-2019_20220401ANALYSIS OF COLOR CONCENTRATIONS IN THE PIGEON RIVER MARCH 4, 2019 AQUAETER, INC. R&S 2189886_1 SECTION 1.0 INTRODUCTION Blue Ridge Paper Products Inc. doing business as "Evergreen Packaging" (Evergreen), operates the Canton pulp and paper mill ("Canton Mill") in Canton, North Carolina. Since 1988, the Mill has reduced color loadings to the Pigeon River by more than 90%. Since 2001 the Canton Mill has sampled and analyzed True and Apparent Color in the Pigeon River upstream from the Mill's discharge and approximately 0.4-mile downstream at the Fibreville Bridge.' In 2009, Evergreen retained AquAeTer to sample and analyze True and Apparent Color in the Pigeon River and its tributaries. Based on the Mill's data, and the data collected by AquAeTer, "A Comprehensive Assessment and Analysis of Color in the Pigeon River2" was developed. In January 2018, AquAeTer issued a follow-up analysis on data collected since 2009, "Analysis of Color Concentrations in the Pigeon Rivera." This report updates the analysis to include the data collected in 2018. In addition to the data collected by the Mill, the Tennessee Department of Environment and Conservation (TDEC) collects color data on the Pigeon River at the state line located at Waterville, N.C4. PURPOSE OF REPORT This report supplements the Comprehensive Assessment and Analysis of Color in the Pigeon River with an analysis of color concentrations in the Pigeon River upstream from the Canton Mill at Park Street and downstream from the Mill's discharge at the Fibreville Bridges. The report compares the color concentrations at Fibreville and the difference in concentration 1 NPDES Permit NC 0000272 issued to the Canton Mill by the North Carolina Department of Environmental Quality requires the sampling. The Canton Mill also samples and analyzes color concentrations at Hepco (approximately 20 river miles downstream) and at Brown's Bridge in Tennessee (approximately 38 miles downstream), approximately 'A mile downstream from the Duke Energy Progress Hydro -electric plant. 2 AquAeTer, Inc. (2014). Comprehensive Assessment and Analysis of Color in the Pigeon River. Brentwood: AquAeTer, Inc. 3 AquAeTer, Inc. January 31, 2018. Analysis of Color Concentrations in the Pigeon River. Brentwood: AquAeTer, Inc. 4 This dataset is not as extensive as the dataset collected by the Mill. No information is given in the TDEC database as to what time the samples were collected or if the hydroelectric plant was generating power at the time of collection. 5 The report will also reference color concentrations at the NC / Tennessee state line and at a similar stream from the same Ecoregion. 2 between the upstream and downstream stations from July 2010 through December 2018. This is the period that the current NPDES permit and associated effluent limits have been in effect. CONCLUSIONS The long-term daily average contribution from the Canton Mill to true color in the Pigeon River since July 2010 is 22 true color units at flows greater than or equal to the annual 30Q2.6 The long term daily average color concentration at the Fibreville Bridge at flows greater than or equal to the annual 30Q2 is 36 true color units. The 90th percentile of the long term contribution of true color to the Pigeon River from the Canton Mill does not exceed 43 true color units for any month of the year at flows greater than or equal to the monthly 30Q2. 8The difference in the long-term daily average color concentration at Park Street in Canton (13 true color units), upstream from the Canton Mill discharge, and the long term daily average color concentration at the North Carolina/Tennessee state line (15 true color units), is 2 true color units.9 This difference is minimal and imperceptible to the human eye. METHODOLOGY AquAeTer has evaluated the color in the Pigeon River upstream from the Canton Mill discharge and at the Fibreville Bridge. The dataset used for this analysis extends from July 1, 2010 through December 31, 20181°, unless otherwise noted. The color data were also evaluated in conjunction with the flows in the River. In particular, monthly flows were evaluated so that distinct hydrologic/meteorologic periods that are statistically equivalent, but occur with the varying background natural color that occurs in the River over the course of the different seasons, would be analyzed separately but equivalently. 6 Table 5, page 11 7 Table 3, page 9 8 Table 5, page 11 9 Table 4, page 10 and Table 6, page 12. 10 This is the period of the current NPDES Permit. 3 SECTION 2.0 ANALYSIS OF STREAM FLOWS 15A N.C.A.C. 2B.0206 (a) (5) specifies that aesthetic standards will be met at flows greater than or equal to the minimum average flow for a period of 30 consecutive days that has an average recurrence of once in two years (30Q2). The actual period for the calculation is not specified. Historically, the period used has been an annual number, so an annual 30Q2 has been calculated for the analyses in this report. However, the annual 30Q2 event is not reflective of the actual stream conditions through the year for this stream. The chance for the annual 30Q2 to occur in any given month for an equivalent 30-day period is much greater than a 2-year return interval, which is not in keeping with the NC standard. The period that is presented in this report is for a monthly basis, which more accurately reflects the hydrologic cycle over the course of the year. A comparison of the monthly 30Q2's to the annual 30Q2 is presented in Figure 1. Each of the monthly 30Q2 Table 1. 30Q2 Monthly and Yearly Flows and flows plotted in Figure 1 is statistically equivalent to the other months meaning they have the same statistical probability of occurring. However, the annual 30Q2 is not statistically likely to occur in four months, and represents a greater than a two- year return interval in the other eight months. The actual calculated flows are provided in Table 1. This demonstrates that while the annual 30Q2 may statistically have a 50% chance of occurring in any given year, the actual chance of the annual 30Q2 Recurrence Intervals PERIOD 30Q2 (cfs) Chance of Annual Flow Occurring (1 in _ Yrs) (%) January 377 55.9 1.8 February 425 >89 <1.1 March 453 >89 <1.1 April 423 >89 <1.1 May 294 >89 <1.1 June 213 58.6 1.7 July 156 18.1 5.5 August 131 4.7 21.4 September 136 4.5 22.1 October 174 4.5 22.4 November 208 9.8 10.3 December 279 40.8 2.5 Annual 91.0 2 50 flow occurring 50% of the time will not occur in any given month. The United States Environmental Protection Agency (USEPA) also recognizes that, in some cases, streams need to and can be evaluated on a monthly basis" due to the variable hydrologic conditions found. This analysis is and has been applied in many southern states as well "US EPA. (1997). Technical Guidance Manual for Performing Wasteload Allocations, Book II.• Streams and Rivers - Part 1: Biochemical Oxygen Demand/Dissolved Oxygen and Nutrients/Eutrophication. Washington, DC: US EPA. 4 as in some northern states and was originally proposed by the old U.S. Public Health Service, or pre-USEPA.12 15A NCAC 02B .0206 (a) states that water quality based effluent limitations shall be developed to allow appropriate frequency and duration of deviations from the water quality standards. The North Carolina statute is in line with the USEPA guidance. The monthly 30Q2 analyses represent a precise analysis of the same hydrologic event for each month of the year and do not introduce bias in the analyses due to multiple months with different hydrologic and meteorologic events not related to the same statistical event 30Q2 or 50% occurrence interval. In other words, an annual calculation can be calculated but it has no chance to occur 50% of the time in any given month. Figure 1. 500 450 400 350 0 300 *'1 250 d 200 CI 150 w 100 50 0 Comparison of Annual and Monthly 30Q2 Low Flows ♦ • • • • • • .- 1 if if 11 11 11 11 1• IF 1 I I I I I I I I I I I I 0, ) 7-: a) 0 0— Po sio MONTH • Monthly 30Q2 ■ Annual 30Q2 a a 0 o 7 0 4 12 There are multiple NPDES Permits in the southeast which use monthly flow limits (DS Smith Riceboro on the North Newport River and Georgia Pacific's Brunswick Mill on the Turtle River (Ga.)), (Georgia Pacific mill in Naheola, Alabama on the Tombigbee River and West Rock Mill on the Tombigbee (Alabama)) and (Domtar Mill at Ashdown, Arkansas). 5 SECTION 3.0 ANALYSIS OF COLOR CONCENTRATIONS The Canton Mill has been collecting in -stream color data since 2001. AquAeTer collected samples from 2009 through 2011 in the stream and in the tributaries. There are 1,601 days with measurements collected at Fibreville since January 1, 2001. This report focuses on the period beginning July 1, 2010, the effective date of the most recent NPDES Permit.13 The analyses presented evaluate True Color in the River in various ways. The first is an analysis of the samples collected at Fibreville. This location is approximately 0.4-mile downstream from the Mill's outfall, and has been considered the compliance point or edge of mixing zone. The dataset for the period July 1, 2010 through December 31, 2018, as well as the entire period of record was evaluated. The Comprehensive Assessment and Analysis of Color detailed that concentration in the River is not related to flow, but the color loading or pounds per day can be reasonably predicted based on the flow. The predicted mass loading can then be converted back to a concentration in order to predict a concentration. However, the analysis in this report focuses on measured concentration data. EVALUATION OF DATA Calculation of the Average (Mean) The first evaluation is the proper identification of an average. The arithmetic mean is a common way to calculate an average. An arithmetic mean is simply the sum of the individual values divided by the number of values, or mathematically: n Xi x= — n i=1 1 The arithmetic mean is strongly influenced by both large and small values. When a dataset is normally distributed, the arithmetic mean is appropriate. However, when a dataset is skewed, the arithmetic mean will no longer represent the central tendency of the dataset. Another average is the median value. 13 This report presents an analysis of color concentrations for the period July 1, 2010 — December 31, 2017. The specified term of the current NPDES Permit is July 1, 2010 - June 30, 2015. However, Evergreen timely submitted its renewal application on December 31 2014. As such, the current permit is administratively continued pursuant to N.C. Gen. Stats. 150B-3 pending final action by NCDEQ on the permit. 6 A skewed dataset may follow a log -normal distribution. For these datasets, the mean and median are calculated using the formulas: Mean, Yin = exp 1 exp (2 x (x — x)2) �n n a i=1 n �i=1 n — x) z * exp (En 1(xl n 1) \ 1 Median, Yin = exp i=1 Calculation of the 90th Percentile 2 n ln(xi) ) 2 3 The second evaluation is to calculate the 90th percentile of the dataset. The 90th percentile method is used and accepted by EPA to determine if a set of data for a pollutant parameter is meeting a numerical water quality standard. The 90th percentile value is greater than 90% of the distribution fit to the dataset. Conversely, 10% of the distribution fit to the dataset is equal to or greater than the 90th percentile value. Since the percentile is based on the fit of the distribution, it is possible to have more than 10% of the actual collected dataset that are greater than the 90th percentile. For a normally distributed dataset, the 90th percentile is calculated using the formula: (xi — 42 Normal 90th percentile, x90 = c-1(0.9) * s + Y = 1.282 * + x i=1 4 Similarly, for a log -normally distributed dataset the 90th percentile is calculated using the formula: Log — normal 90th percentile, x90,1n / n (ln(xi) — En 1 lnnxt))2 = exp 1.282 * i=1 5 7 Determination of Dataset Distribution The evaluation of the full dataset that extends from January 1, 2001 to the present indicates that most months follow a log -normal distribution. The goodness of fit results using the Anderson - Darling (A-D) test for both normal and log -normal distributions for the full dataset and the most recent dataset are presented in Table 2. When the result presented in the table is greater than 0.05, relating to a 95% probability, the dataset fit the specified distribution. The best fit distribution for each case is highlighted yellow in Table 2. The appropriate calculations will be used for calculating the monthly averages. Table 2. Goodness of Fit for a 95% Probability for Dataset at Fibreville MONTH Normal Distribution Log -Normal Distribution Full Dataset July 1, 2010 - Present Full Dataset July 1, 2010 - Present January 0.00 0.00 0.33 0.23 February 0.00 0.00 0.42 0.63 March 0.00 0.11 0.27 0.47 April 0.00 0.00 0.32 0.03 May 0.00 0.00 0.05 0.18 June 0.00 0.00 0.14 0.36 July 0.00 0.89 0.39 0.01 August 0.00 0.00 0.29 0.46 September 0.00 0.00 0.01 0.01 October 0.00 0.00 0.17 0.32 November 0.00 0.00* 0.00 0.00 December 0.00 0.01 0.04 0.01 Annual 0.00 0.00 0.00 0.00* I Note: * = Value does not pass A-D test, but this distribution was used. EVALUATION OF IN -STREAM COLOR AVERAGES Long-term Daily Average for each Month for In -Stream Color Concentrations Measured at Fibreville The long-term average of the daily concentration values for each month for the period from July 1, 2010 through December 31, 2018 is presented in Table 3. This table demonstrates that the color concentration measurements at Fibreville are less than or equal to 40 color units on a long- term average for each month when flows are greater than or equal to the monthly 30Q2. The 90th percentile column is presented since that method is used and accepted by the USEPA to determine if a set of data for a pollutant parameter is meeting a numerical water quality standard. The table shows that one month is as high as 60 color units at the 90th percentile, while the remaining months are 51 color units or less. Though there is no North Carolina numerical water quality standard for 8 color, discussions of acceptable target values for the Pigeon River in the range of 50 to 100 have been considered in the past. All of the values in Table 3 fall within or below this range. Table 3. Long-term Daily Average Color Concentration for each Month for In -Stream Measurements at Fibreville for July 1, 2010 through December 31, 2018 MONTH DISTRI- BUTION TOTAL NUMBER OF VALUES LONG-TERM DAILY AVG. WHEN FLOWS >=A30Q2 (mg/L) LONG-TERM DAILY AVG. WHEN FLOWS >=M30Q2 (mg/L) LONG-TERM 90th PER - CENTILE WHEN FLOWS >=M30Q2 (mg/L) Jan. LN 70 29 19 34tP Feb. LN 65 25 18 28 Mar. LN 73 26 20 29 Apr. LN 68 22 19 28 May LN 72 25 21 32 Jun. LN 62 41 27 38 Jul. N 78 48 34 51 Aug. LN 82 46 40 60 Sep. LN 78 51 37 50 Oct. LN 79 43 33 48 Nov. N 80 45 29 50 Dec. LN 79 34 24 38 Annual LN 886 36 27 45 Note: LN = Log Normal A30Q2 = Annual 30Q2 Condition M30Q2 = Monthly 30Q2 Condition 'F — A sample collected on January 11, 2018 was collected at a time when the flow in the River was less than the M30Q2 flow. The daily average flow was greater than the M30Q2 flow, so the measurement was included in this analysis. Without it, the 90th percentile would be 31 for January. The values in Table 3 do not represent a separation of background color and color contributed by the Mill. The long-term daily average Park Street measurements for each month are presented in Table 4. 9 Table 4. Long -Term Daily Average Color Concentration at Park Street Upstream for July 1, 2010 through December 31, 2018 MONTH DISTRI- BUTION TOTAL NUMBER OF VALUES LONG-TERM DAILY AVG. WHEN FLOWS >=A30Q2 (mg/L) LONG-TERM DAILY AVG. WHEN FLOWS >=M30Q2 (mg/L) LONG-TERM 90th PER - CENTILE WHEN FLOWS >=M30Q2 (mg/L) Jan. LN 70 11 12 22 Feb. LN 65 10 11 20 Mar. N 73 10 12 23 Apr. LN 68 12 15 28 May N 71 12 12 17 Jun. LN 61 15 13 26 Jul. LN 78 15 15 22 Aug. N 82 14 15 25 Sep. N 77 17 17 31 Oct. LN 79 17 19 31 Nov. LN 79 16 17 26 Dec. LN 79 14 16 30 Annual LN 883 13 15 26 Note: LN = Log Normal A30Q2 = Annual 30Q2 Condition M30Q2 = Monthly 30Q2 Condition The variable nature of color in the Pigeon River upstream from the Mill is presented in Table 4. In some months the expected long-term daily average when flows are greater than or equal to the Monthly 30Q2 are as high as 19 color units. The 90th percentile values in some months are as high as 31 color units. Background concentrations have been measured as high as 94 mg/L in the Pigeon River upstream from the Mi11.14 This means that any instantaneous numerical water quality target value must account for the background at the time of the sample. Determination of In -Stream Color Delta at Fibreville The Pigeon River coming to the Mill in Canton has been measured for color on a routine basis. Because of the variability in background color as shown in Table 4, an in -stream delta between the background and the downstream location is more appropriate to evaluate the Mill's contribution to color in the River. Similarly to the in -stream values, the majority of the long-term daily average delta concentrations for each month do not fit a normal distribution. The long-term daily average in -stream delta concentrations for each month are provided in Table 5. This table demonstrates that for any month, the long term daily average contribution of the Canton Mill to color at Fibreville when flows are greater than or equal to monthly 30Q2 is 25 true 14 December 24, 2015 at Park Street Bridge in Canton 10 color units or less. The 90th percentile of color contribution of the Canton Mill does not exceed 43 true color units for any month when flows are greater than or equal to the monthly 30Q2. Table 5. Long -Term Daily Average In -Stream Delta Color Concentration at Fibreville Bridge downstream for Each Month for July 1, 2010 through December 31, 2018 MONTH DISTRI- BUTION TOTAL NUMBER OF VALUES LONG-TERM DAILY AVG. WHEN FLOWS >=A30Q2 (mg/L) LONG-TERM DAILY AVG. WHEN FLOWS >=M30Q2 (mg/L) LONG-TERM 90th PER - CENTILE WHEN FLOWS >=M30Q2 (mg/L) Jan. LN 70 18 7 16 Feb. LN 65 15 7 12 Mar. LN 73 16 8 15 Apr. LN 68 11 5 11 May LN 72 13 10 19 Jun. LN 62 26 14 23 Jul. N 78 33 20 36 Aug. LN 82 32 25 43 Sep. LN 78 35 18 34 Oct. LN 79 26 14 29 Nov. LN 80 30 12 25 Dec. LN 79 22 9 32 Annual LN 883 22 12 22 Note: LN = Log Normal A30Q2 = Annual 30Q2 Condition M30Q2 = Monthly 30Q2 Condition Determination of Average Color on the French Broad River and Comparison to the Pigeon River at or near the North Carolina — Tennessee state line For comparison purposes, the color measurements collected on the French Broad River upstream from Newport, Tennessee are also included in Table 6. It is noted that the difference between the upstream and downstream locations on the French Broad River is greater than the Pigeon River for the same time period. It is noted that the dataset for the Pigeon River is much more extensive, meaning that the conditions monitored are more likely representative of conditions present at any given time. Both Rivers follow the general expectation that color increases in the downstream direction as stream order increases. The Tennessee Department of Environment and Conservation collects samples on the Pigeon River near the state line, as well as, on the French Broad River at the Highway 70 Bridge (near Del Rio, TN) and at the Highway 321 Bridge (near Newport, TN). There are not enough data points to calculate long-term daily averages for each month, nor to determine the proper 11 distribution of the datasets. Averages of the three datasets are presented, along with the number of samples in each calculation. There are two things to note when evaluating the comparison between the upstream station and the station at the state line. First, the measurements collected at Park Street are collected by the Canton Mill, while the measurements collected at the state line are collected by TDEC. The second thing is that within the time frame analyzed, the Canton Mill has collected 882 measurements, while TDEC has collected 243 measurements. The difference in the number of samples collected means that the Canton Mill's dataset represents a more varied dataset in terms of the environmental conditions present, such as low -flow, rain events, ice cover, etc. It is noted that TDEC deliberately does not sample when natural flow conditions are elevated and thus does not sample the full range of hydrologic and meteorologic periods during the year. The TDEC SOP for not sampling during elevated flow conditions is based on safety, although the sampling station utilized by TDEC at the State Line is dangerous regardless of the flow in the River. Table 6. Comparison of Color Concentration for In -Stream Measurements on Pigeon and French Broad Rivers (Post July 1, 2010) PARAMETER PIGEON RIVER AT PARK STREET IN CANTON PIGEON RIVER NEAR NC/TN STATE LINE FRENCH BROAD RIVER NEAR DEL RIO, TN FRENCH BROAD RIVER NEAR NEWPORT, TN Drainage Area (sq. mi.) 130 538 1,713 1,858 Number of Samples 882 243 30 24 Samples Collected by EPI TDEC TDEC TDEC Average Color, mg/L 13 15 19 24 Minimum Color, mg/L 1 5 3 3 Maximum Color, 94 43* 63 110 mg/L Note: Both French Broad TDEC stations are upstream from the confluence of the Pigeon River and the French Broad River near Newport, Tennessee. *: A sample of 95 was measured in 2008 by TDEC at this location. The Pigeon River near the state line and the French Broad River near Del Rio are especially suited for comparison purposes since 1) they both drain the identical ecosystem classification; 2) they are both level 5 on the Schuler stream classification system (stream order); and 3) the French Broad near Del Rio has no known large sources of color discharging to it. The comparison shows that the Pigeon River near the state line actually has less color than the French Broad River near Del Rio when compared to an equivalent stream system (i.e., same ecosystem and same order 12 stream). This indicates the Pigeon River at the state line does not have color levels outside of the expected range for a stream with no large point source of color discharging to it. These data also show the difference in color at the Park Street Bridge on the Pigeon River and the color at the state line on the Pigeon River is only 2 color units which is imperceptible by the human eye. 13 SECTION 4.0 FINDINGS AND CONCLUSIONS FINDINGS FOR THE PERIOD JULY 1, 2010 THRU DECEMBER 31, 2018: Based on a methodology used by and recognized by EPA, 30Q2 values for each month of the year for the Pigeon River more accurately reflect the hydrologic cycle over the course of the year. Although an annual 30Q2 flow can be calculated, the annual event has no chance of occurring in any given month of the year for 50% of the time. Color concentration measurements at Fibreville are less than or equal to 40 color units on a long- term average for each month when flows are greater than or equal to the monthly 30Q2. The 90th percentile of the long-term daily color concentrations at Fibreville when flows are equal to or greater than the monthly 30Q2, ranged from 28 in February and April to 60 in August. (90th percentile was examined from EPA's guidance on comparing a set of data to a specific water quality standard i.e. if the 90th percentile is less than a target value, then water quality standards are being met). The long term daily average color concentration added, i.e., the delta, to the Pigeon River by the Mill, at flows greater than or equal to the monthly 30Q2, is less than or equal to 25 color units for any month. The 90th percentile of the color concentration added by the Mill, at flows greater than or equal to the monthly 30Q2, is less than or equal to 43 color units for all months. The color concentrations in the Pigeon River upstream from the Mill are variable. In some months the expected long term daily average color concentration, when flows are greater than or equal to the monthly 30Q2, are as high as 19 color units; and 90th percentile values in some months are as high as 31 color units. Also, color concentrations upstream from the Mill have been measured as high as 94 color units. This means that any instantaneous numerical water quality target value must account for the background at the time of the sample. OTHER FINDINGS: Comparison of the French Broad River near Del Rio shows the Pigeon River at the Stateline does not have color levels outside of the expected range for a stream with no large point source of color discharging to it. The difference in the long-term daily average color concentration at Park Street in Canton, upstream from the Canton Mill discharge, and the long-term daily average color concentration at the North Carolina -Tennessee Stateline is 2 true color units. 14 CONCLUSIONS: The long term daily average contribution (delta) of the Canton Mill to true color in the Pigeon River is 22 color units at flows greater than or equal to the annual 30Q2. The long term daily average color concentration at the Fibreville Bridge at flows greater than or equal to the annual 30 Q2 is 36 true color units. The 90th percentile of the long-term contribution of true color to the Pigeon River from the Canton does not exceed 43 true color units for any month of the year at flows greater than or equal to the monthly 30Q2. The difference in the long term daily average color concentration at Park Street in Canton (13 true color units), upstream from the Canton Mill discharge and the long term daily average color concentration at the North Carolina -Tennessee state line (15 true color units) is 2 true color units. This difference is minimal and imperceptible to the human eye. Though there is no North Carolina numerical water quality standard for color, discussions of acceptable target values for the Pigeon River in the range of 50 to 100 have been considered in the past. The long-term average and 90th percentile values at Fibreville and the long-term average and 90th percentile contributed by the Mill meet this target range. 15