Loading (50 kb)...'
(continued) f the pre-existing discharges.
(c) The term pre-existing discharge means any discharge resulting from mining activities that have been abandoned prior to the time of a remining permit application. This term shall include a pre-existing discharge that is relocated as a result of the implementation of best management practices (BMPs) contained in the Pollution Abatement Plan.
(d) The term steep slope means any slope above twenty degrees or such lesser slope as may be defined by the regulatory authority after consideration of soil, climate, and other characteristics of a region or State. This term does not apply to those situations in which an operator is mining on flat or gently rolling terrain, on which an occasional steep slope is encountered and through which the mining operation is to proceed, leaving a plain or predominantly flat area.
(e) The term new source remining operation means a remining operation at a coal mine where mining first commences after February 22, 2002 and subsequently becomes an abandoned mine.
§ 434.71 Applicability.
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(a) This subpart applies to pre-existing discharges that are located within or are hydrologically connected to pollution abatement areas of a coal remining operation.
(b) A pre-existing discharge that is intercepted by active mining or that is commingled with waste streams from active mining areas for treatment is subject to the provisions of §434.61 Commingling of waste streams. For the purposes of this subpart, §434.61 requires compliance with applicable BPT, BAT, BCT, and NSPS effluent limitations in subparts C, D, and F of this part. Section 434.61 applies to the commingled waste stream only during the time when the pre-existing discharge is intercepted by active mining or is commingled with active mine wastewater for treatment or discharge. After commingling has ceased, the pre-existing discharge is subject to the provisions of this part.
(c) In situations where coal remining operations seek reissuance of an existing remining permit with BPJ limitations and the regulatory authority determines that it is not feasible for a remining operator to re-establish baseline pollutant levels in accordance with the statistical procedures contained in Appendix B of this part, pre-existing discharge limitations at existing remining operations shall remain subject to baseline pollutant levels established during the original permit application.
(d) The effluent limitations in this subpart apply to pre-existing discharges until the appropriate SMCRA authority has authorized bond release.
§ 434.72 Effluent limitations attainable by the application of the best practicable control technology currently available (BPT).
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(a) The operator must submit a site-specific Pollution Abatement Plan to the permitting authority for the pollution abatement area. The plan must be approved by the permitting authority and incorporated into the permit as an effluent limitation. The Pollution Abatement Plan must identify characteristics of the pollution abatement area and the pre-existing discharges. The Pollution Abatement Plan must be designed to reduce the pollution load from pre-existing discharges and must identify the selected best management practices (BMPs) to be used. The plan must describe the design specifications, construction specifications, maintenance schedules, criteria for monitoring and inspection, and expected performance of the BMPs. The BMPs must be implemented as specified in the plan.
(b) (1) Except as provided in 40 CFR 125.30 through 125.32 and paragraph (b)(2) of this section, the following effluent limits apply to pre-existing discharges:
Effluent Limitations
------------------------------------------------------------------------
Pollutant Requirement
------------------------------------------------------------------------
(i) Iron, total........................ May not exceed baseline
loadings (as defined by
Appendix B of this part).
(ii) Manganese, total.................. May not exceed baseline
loadings (as defined by
Appendix B of this part).
(iii) Acidity, net..................... May not exceed baseline
loadings (as defined by
Appendix B of this part).
(iv) TSS............................... During remining and
reclamation, may not exceed
baseline loadings (as defined
by Appendix B of this part).
Prior to bond release, the pre-
existing discharge must meet
the applicable standards for
TSS or SS contained in Subpart
E. \1\
------------------------------------------------------------------------
\1\ A pre-existing discharge is exempt from meeting standards in Subpart
E of this part for TSS and SS when the permitting authority determines
that Subpart E standards are infeasible or impractical based on the
site-specific conditions of soil, climate, topography, steep slopes,
or other baseline conditions provided that the operator demonstrates
that significant reductions of TSS and SS will be achieved through the
incorporation of sediment control BMPs into the Pollution Abatement
Plan as required by paragraph (a) of this section.
(2) If the permitting authority determines that it is infeasible to collect samples for establishing the baseline pollutant levels pursuant to paragraph (b)(1) of this section, and that remining will result in significant improvement that would not otherwise occur, then the numeric effluent limitations in paragraph (b)(1) of this section do not apply. Pre-existing discharges for which it is infeasible to collect samples for determination of baseline pollutant levels include, but are not limited to, discharges that exist as a diffuse groundwater flow that cannot be assessed via sample collection; a base flow to a receiving stream that cannot be monitored separate from the receiving stream; a discharge on a steep or hazardous slope that is inaccessible for sample collection; or, a number of pre-existing discharges so extensive that monitoring of individual discharges is infeasible.
§ 434.73 Effluent limitations attainable by application of the best available technology economically achievable (BAT).
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Except as provided in 40 CFR 125.30 through 125.32 and 434.72(b)(2), a pre-existing discharge must comply with the effluent limitations listed in §434.72(b) for net acidity, iron and manganese. The operator must also submit and implement a Pollution Abatement Plan as required in §434.72(a) .
§ 434.74 Effluent limitations attainable by application of the best conventional pollutant control technology (BCT).
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Except as provided in 40 CFR 125.30 through 125.32 and 434.72(b)(2), a pre-existing discharge must comply with the effluent limitations listed in §434.72(b) for total suspended solids. The operator must also submit and implement a Pollution Abatement Plan as required in §434.72(a).
§ 434.75 New source performance standards (NSPS).
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Except as provided in §434.72(b)(2), a pre-existing discharge from a new source remining operation must comply with the effluent limitations listed in §434.72(b) for iron, manganese, acidity and total suspended solids. The operator must also submit and implement a Pollution Abatement Plan as required in §434.72(a).
Subpart H—Western Alkaline Coal Mining
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Source: 67 FR 3407, Jan. 23, 2002, unless otherwise noted.
§ 434.80 Specialized definitions.
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(a) The term brushing and grubbing area means the area where woody plant materials that would interfere with soil salvage operations have been removed or incorporated into the soil that is being salvaged.
(b) The term regraded area means the surface area of a coal mine that has been returned to required contour.
(c) The term sediment means undissolved organic and inorganic material transported or deposited by water.
(d) The term sediment yield means the sum of the soil losses from a surface minus deposition in macro-topographic depressions, at the toe of the hillslope, along field boundaries, or in terraces and channels sculpted into the hillslope.
(e) The term topsoil stockpiling area means the area outside the mined-out area where topsoil is temporarily stored for use in reclamation, including containment berms.
(f) The term western coal mining operation means a surface or underground coal mining operation located in the interior western United States, west of the 100th meridian west longitude, in an arid or semiarid environment with an average annual precipitation of 26.0 inches or less.
§ 434.81 Applicability.
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(a) This subpart applies to alkaline mine drainage at western coal mining operations from reclamation areas, brushing and grubbing areas, topsoil stockpiling areas, and regraded areas.
(b) This subpart applies to drainage at western coal mining operations from reclamation areas, brushing and grubbing areas, topsoil stockpiling areas, and regraded areas where the discharge, before any treatment, meets all the following requirements:
(1) pH is equal to or greater than 6.0;
(2) Dissolved iron concentration is less than 10 mg/L; and
(3) Net alkalinity is greater than zero.
(c) The effluent limitations in this subpart apply until the appropriate SMCRA authority has authorized bond release.
§ 434.82 Effluent limitations attainable by the application of the best practicable control technology currently available (BPT).
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Except as provided in 40 CFR 125.30 through 125.32, the following effluent limitations apply to mine drainage from applicable areas of western coal mining operations:
(a) The operator must submit a site-specific Sediment Control Plan to the permitting authority that is designed to prevent an increase in the average annual sediment yield from pre-mined, undisturbed conditions. The Sediment Control Plan must be approved by the permitting authority and be incorporated into the permit as an effluent limitation. The Sediment Control Plan must identify best management practices (BMPs) and also must describe design specifications, construction specifications, maintenance schedules, criteria for inspection, as well as expected performance and longevity of the best management practices.
(b) Using watershed models, the operator must demonstrate that implementation of the Sediment Control Plan will result in average annual sediment yields that will not be greater than the sediment yield levels from pre-mined, undisturbed conditions. The operator must use the same watershed model that was, or will be, used to acquire the SMCRA permit.
(c) The operator must design, implement, and maintain BMPs in the manner specified in the Sediment Control Plan.
§ 434.83 Effluent limitations attainable by application of the best available technology economically achievable (BAT).
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Except as provided in 40 CFR 125.30 through 125.32, any existing western coal mining operation with drainage subject to this subpart must meet the effluent limitations in §434.82.
§ 434.84 Effluent limitations attainable by application of the best conventional pollutant control technology (BCT). [Reserved]
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§ 434.85 New source performance standards (NSPS).
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Any new source western coal mining operation with drainage subject to this subpart must meet the effluent limitations in §434.82.
Appendix A to Part 434—Alternate Storm Limitations for Acid or Ferruginous Mine Drainage
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View or download PDF
Appendix B to Part 434—Baseline Determination and Compliance Monitoring for Pre-existing Discharges at Remining Operations
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I. General Procedure Requirements
a. This appendix presents the procedures to be used for establishing effluent limitations for pre-existing discharges at coal remining operations, in accordance with the requirements set forth in Subpart G; Coal Remining. The requirements specify that pollutant loadings of total iron, total manganese, total suspended solids, and net acidity in pre-existing discharges shall not exceed baseline pollutant loadings. The procedures described in this appendix shall be used for determining site-specific, baseline pollutant loadings, and for determining whether discharge loadings during coal remining operations have exceeded the baseline loading. Both a monthly (single-observation) procedure and an annual procedure shall be applied, as described below.
b. In order to sufficiently characterize pollutant loadings during baseline determination and during each annual monitoring period, it is required that at least one sample result be obtained per month for a period of 12 months.
c. Calculations described in this appendix must be applied to pollutant loadings. Each loading value is calculated as the product of a flow measurement and pollutant concentration taken on the same date at the same discharge sampling point, using standard units of flow and concentration (to be determined by the permitting authority). For example, flow may be measured in cubic feet per second, concentration in milligrams per liter, and the pollutant loading could be calculated in pounds per year.
d. Accommodating Data Below the Maximum Daily Limit at subpart C of this part. In the event that a pollutant concentration in the data used to determine baseline is lower than the daily maximum limitation established in subpart C of this part for active mine wastewater, the statistical procedures should not establish a baseline more stringent than the BPT and BAT effluent standards established in subpart C of this part. Therefore, if the total iron concentration in a baseline sample is below 7.0 mg/L, or the total manganese concentration is below 4.0 mg/L, the baseline sample concentration may be replaced with 7.0 mg/L and 4.0 mg/L, respectively, for the purposes of some of the statistical calculations in this Appendix B. The substituted values should be used for all methods in this Appendix B with the exception of the calculation of the interquartile range (R) in Method 1 for the annual trigger (Step 3), and in Method 2 for the single observation trigger (Step 3). The interquartile range (R) is the difference between the quartiles M–1 and M1; these values should be calculated using actual loadings (based on measured concentrations) when they are used to calculate R. This should be done in order to account for the full range of variability in the data.
II. Procedure for Calculating and Applying a Single-Observation (Monthly) Trigger
Two alternative methods are provided for calculating a single-observation trigger. One method must be selected and applied by the permitting authority for any given remining permit.
A. Method 1 for Calculating a Single Observation Trigger (L)
(1) Count the number of baseline observations taken for the pollutant of interest. Label this number n. In order to sufficiently characterize pollutant loadings during baseline determination and during each annual monitoring period, it is required that at least one sample result be obtained per month for a period of 12 months.
(2) Order all baseline loading observations from lowest to highest. Let the lowest number (minimum) be x(1), the next lowest be x(2), and so forth until the highest number (maximum) is x(n).
(3) If fewer than 17 baseline observations were obtained, then the single observation trigger (L) will equal the maximum of the baseline observations (x(n)).
(4) If at least 17 baseline observations were obtained, calculate the median (M) of all baseline observations:
Instructions for calculation of a median of n observations:
If n is odd, then M equals x(n/2+1/2).
For example, if there are 17 observations, then M = X(17/2+1/2) = x(9), the 9th highest observation.
If n is even, then M equals 0.5 * (x(n/2) + x(n/2+1)).
For example, if there are 18 observations, then M equals 0.5 multiplied by the sum of the 9th and 10th highest observations.
(a) Next, calculate M1 as the median of the subset of observations that range from the calculated M to the maximum x(n); that is, calculate the median of all x larger than or equal to M.
(b) Next, calculate M2 as the median of the subset of observations that range from the calculated M1 to x(n) ; that is, calculate the median of all x larger than or equal to M1.
(c) Next, calculate M3 as the median of the subset of observations that range from the calculated M2 to x(n) ; that is, calculate the median of all x larger than or equal to M2.
(d) Finally, calculate the single observation trigger (L) as the median of the subset of observations that range from the calculated M3 to x(n).
Note: When subsetting the data for each of steps 3a–3d, the subset should include all observations greater than or equal to the median calculated in the previous step. If the median calculated in the previous step is not an actual observation, it is not included in the new subset of observations. The new median value will then be calculated using the median procedure, based on whether the number of points in the subset is odd or even.
(5) Method for applying the single observation trigger (L) to determine when the baseline level has been exceeded
If two successive monthly monitoring observations both exceed L, immediately begin weekly monitoring for four weeks (four weekly samples).
(a) If three or fewer of the weekly observations exceed L, resume monthly monitoring
(b) If all four weekly observations exceed L, the baseline pollution loading has been exceeded.
B. Method 2 for Calculating a Single Observation Trigger (L)
(1) Follow Method 1 above to obtain M1 (the third quartile, that is, the 75th percentile).
(2) Calculate M-1 as the median of the baseline data which are less than or equal to the sample median M.
(3) Calculate interquartile range, R = (M1 - M-1).
(4) Calculate the single observation trigger L as
L = M1 + 3 * R
(5) If two successive monthly monitoring observations both exceed L, immediately begin weekly monitoring for four weeks (four weekly samples).
(a) If three or fewer of the weekly observations exceed L, resume monthly monitoring
(b) If all four weekly observations exceed L, the baseline pollution loading has been exceeded.
III. Procedure for Calculating and Applying an Annual Trigger
A. Method 1 for Calculating and Applying an Annual Trigger (T)
(1) Calculate M and M1 of the baseline loading data as described above under Method 1 for the single observation trigger.
(2) Calculate M-1 as the median of the baseline data which are less than or equal to the sample median M.
(3) Calculate the interquartile range, R = (M1 - M-1).
(4) The annual trigger for baseline (Tb) is calculated as:
where n is the number of baseline loading observations.
(5) To compare baseline loading data to observations from the annual monitoring period, repeat steps 1–3 for the set of monitoring observations. Label the results of the calculations M' and R'. Let m be the number of monitoring observations.
(6) The subtle trigger (Tm) of the monitoring data is calculated as:
(7) If Tm > Tb, the median loading of the monitoring observations has exceeded the baseline loading.
B. Method 2 for Calculating and Applying an Annual Trigger (T)
Method 2 applies the Wilcoxon-Mann-Whitney test to determine whether the median loading of the monitoring observations has exceeded the baseline median. No baseline value T is calculated.
(1) Steps for Conducting the Wilcoxon-Mann-Whitney Test
(a) Let n be the number of baseline loading observations taken, and let m be the number of monitoring loading observations taken. In order to sufficiently characterize pollutant loadings during baseline determination and during each annual monitoring period, it is required that at least one sample result be obtained per month for a period of 12 months.
(b) Order the combined baseline and monitoring observations from smallest to largest.
(c) Assign a rank to each observation based on the assigned order: the smallest observation will have rank 1, the next smallest will have rank 2, and so forth, up to the highest observation, which will have rank n + m.
(1) If two or more observations are tied (have the same value), then the average rank for those observations should be used. For example, suppose the following four values are being ranked:
3, 4, 6, 4
Since 3 is the lowest of the four numbers, it would be assigned a rank of 1. The highest of the four numbers is 6, and would be assigned a rank of 4. The other two numbers are both 4. Rather than assign one a rank of 2 and the other a rank of 3, the average of 2 and 3 (i.e., 2.5) is given to both numbers.
(d) Sum all the assigned ranks of the n baseline observations, and let this sum be Sn.
(e) Obtain the critical value (C) from Table 1. When 12 monthly data are available for both baseline and monitoring (i.e., n = 12 and m = 12), the critical value C is 99.
(f) Compare C to Sn. If Sn is less than C, then the monitoring loadings have exceeded the baseline loadings.
(2) Example Calculations for the Wilcoxon-Mann-Whitney Test
BASELINE DATA
----------------------------------------------------------------------------------------------------------------
8.0 9.0 9.0 10.0 12.0 15.0 17.0 18.0 21.0 23.0 28.0 30.0
----------------------------------------------------------------------------------------------------------------
MONITORING DATA
----------------------------------------------------------------------------------------------------------------
9.0 10.0 11.0 12.0 13.0 14.0 16.0 18.0 20.0 24.0 29.0 31.0
----------------------------------------------------------------------------------------------------------------
BASELINE RANKS
----------------------------------------------------------------------------------------------------------------
1.0 3.0 3.0 5.5 8.5 12.0 14.0 15.5 18.0 19.0 21.0 23.0
----------------------------------------------------------------------------------------------------------------
MONITORING RANKS
----------------------------------------------------------------------------------------------------------------
3.0 5.5 7.0 8.5 10.0 11.0 13.0 15.5 17.0 20.0 22.0 24.0
----------------------------------------------------------------------------------------------------------------
Sum of Ranks for Baseline is Sn = 143.5, critical value is Cn, m = 99.
(3) Critical Values for the Wilcoxon-Mann-Whitney Test
(a) When n and m are less than 21, use Table 1.
In order to find the appropriate critical value, match column with correct n (number of baseline observations) to row with correct m (number of monitoring observations) * .
Table 1_Critical Values (C) of the Wilcoxon-Mann-Whitney Test
(for a one-sided test at the 0.001 significance level)
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n m 10 11 12 13 14 15 16 17 18 19 20
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10........................................ 66 79 93 109 125 142 160 179 199 220 243
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11........................................ 68 82 96 112 128 145 164 183 204 225 248
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12........................................ 70 84 99 115 131 149 168 188 209 231 253
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13........................................ 73 87 102 118 135 153 172 192 214 236 259
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14........................................ 75 89 104 121 138 157 176 197 218 241 265
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15........................................ 77 91 107 124 142 161 180 201 223 246 270
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16........................................ 79 94 110 127 145 164 185 206 228 251 276
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17........................................ 81 96 113 130 149 168 189 211 233 257 281
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18........................................ 83 99 116 134 152 172 193 215 238 262 287
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19........................................ 85 101 119 137 156 176 197 220 243 268 293
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20........................................ 88 104 121 140 160 180 202 224 248 273 299
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(b) When n or m is greater than 20 and there are few ties, calculate an approximate critical value using the following formula and round the result to the next larger integer. Let N = n + m.
For example, this calculation provides a result of 295.76 for n = m = 20, and a result of 96.476 for n = m = 12. Rounding up produces approximate critical values of 296 and 97.
(c) When n or m is greater than 20 and there are many ties, calculate an approximate critical value using the following formula and round the result to the next larger integer. Let S be the sum of the squares of the ranks or average ranks of all N observations. Let N = n + m.
In the preceding formula, calculate V using
[67 FR 3408, Jan. 23, 2002]