\ UNITED STATES ENVIRONMENTAL PROTECTION AGENCY o REGION 1650 Arch Street Philadelphia, Pennsylvania 19103-2029 Decision Rationale Total Maximum Daily Loads Acid Mine Drainage Affected Segments Wilson Creek Watershed Somerset County, Pennsylvania Signed Jon M. Capacasa, Director Water Protection Division Date: 6/18/2008 Printed on 100% recycled/recyclable paper with 100% post-consumer fiber and process chlorine free. Customer Service Hotline: 1-800-438-2474 ------- Decision Rationale Total Maximum Daily Loads Acid Mine Drainage Affected Segments Wilson Creek Watershed, Somerset County, Pennsylvania I. Introduction The Clean Water Act (CWA) requires that Total Maximum Daily Loads (TMDLs) be developed for those waterbodies identified as impaired by the state where technology based and other controls will not provide for attainment of water quality standards. A TMDL is a determination of the amount of a pollutant from point, nonpoint, and natural background sources, including a Margin of Safety (MOS) that may be discharged to a waterbody without exceeding water quality standards. The Pennsylvania Department of Environmental Protection (PADEP) Bureau of Watershed Management electronically submitted the Wilson Creek Watershed TMDL, Somerset County, for Acid Mine Drainage Affected Segments (TMDL Report), dated February 29, 2008, to the U.S. Environmental Protection Agency (EPA) for final Agency review on April 15, 2008. This report includes the TMDLs for the three primary metals associated with acid mine drainage (AMD) (i.e., iron, manganese, and aluminum and pH) and addresses one segment on Pennsylvania's 1996 Section 303(d) List of impaired waters. EPA's rationale is based on the TMDL Report and information contained in the attachments to the report. EPA's review determined that the TMDL meets the following seven regulatory requirements pursuant to 40 CFR Part 130: 1. The TMDL is designed to implement applicable water quality standards. 2. The TMDL includes a total allowable load as well as individual wasteload allocations (WLAs) and load allocations (LAs). 3. The TMDL considers the impacts of background pollutant contributions. 4. The TMDL considers critical environmental conditions. 5. The TMDL considers seasonal environmental variations. 6. The TMDL includes a MOS. 7. The TMDL has been subject to public participation. In addition, these TMDLs considered reasonable assurance that the TMDL allocations assigned to the nonpoint sources can be reasonably met. II. Summary Table 1 presents the 1996, 1998 and 2002, Section 303(d) Listing and the 2004 and 2006 Integrated Report listing of information for the impaired segment first listed in 1996 (Pennsylvania's 1996, 1998, 2002 Section 303(d) Lists and 2004, 2006 Integrated Reports were approved by the EPA. The 1996 Section 303(d) List provides the basis for measuring progress under the 1997 lawsuit settlement of American Littoral Society and Public Interest Group of Pennsylvania v. EPA). ------- Table 1. 303(d) Listed Segments - State Water Plan (SWP) Subbasin: 19F HUC: 05020006 Year 1996 1998 2002 2004 2006 2006 2006 2006 2006 2006 2006 Miles 1.0 0.91 0.9 0.9 1.33 0.64 1.86 0.48 0.63 0.37 1.05 Desig- nated Use * * * * Aquatic Life Aquatic Life Aquatic Life Aquatic Life Aquatic Life Aquatic Life Aquatic Life Assessment ID * * * * 7604 12724 12724 12724 12724 12724 12724 Segment ID 4850 4850 4850 4850 * * * * * * * DEP Stream Code 38947 38947 38947 38947 38947 38948 38949 38950 38951 38952 38953 Stream Name Wilson Creek Wilson Creek Wilson Creek Wilson Creek Wilson Creek Wilson Creek, Unt Wilson Creek, Unt Wilson Creek, Unt Wilson Creek, Unt Wilson Creek, Unt Wilson Creek, Unt Desig- nated Use WWF WWF WWF WWF WWF WWF WWF WWF WWF WWF WWF Data Source 305(b) Report SWMP SWMP SWMP SWMP SWMP SWMP SWMP SWMP SWMP SWMP Source RE AMD AMD AMD AMD AMD AMD AMD AMD AMD AMD EPA 305(b) Cause Code Metals Metals Metals Metals Metals pH Metals pH Metals pH Metals pH Metals pH Metals pH Metals pH * Denotes not applicable data for designated reporting year. Resource Extraction = RE Warm Water Fish = WWF Surface Water Monitoring Program = SWMP Abandoned Mine Drainage = AMD See Attachment D of the TMDL Report, Excerpts Justifying Changes Between the 1996, 1998,2002 Section 303(d) Lists and the 2004, 2006 Integrated Report. The use designations for the stream segments in this TMDL can be found in PA Title 25 Chapter 93.9v, Section IV. Table 3 shows the TMDLs for the Wilson Creek Watershed. In 1997, PADEP began utilizing the Statewide Surface Waters Assessment Protocol to assess Pennsylvania's waters. This protocol is a modification of EPA's 1989 Rapid Bioassessment Protocol II and provides for a more consistent approach to conducting biological ------- assessments than previously used methods. The biological assessments are used to determine which waters are impaired and should be included on the State's Section 303(d) List. The TMDLs in this report were developed using a statistical procedure to ensure that water quality criteria are met 99% of the time as required by Pennsylvania's water quality standards at Pennsylvania Code Title 25, Chapter 96.3c. Table 3 of the TMDL Report lists the TMDLs for the Wilson Creek Watershed, addressing metals and pH in the stream segments listed as PADEP stream code 38947. TMDLs are defined as the summation of the point source WLAs, plus the summation of the nonpoint source, LAs plus a MOS and are often shown as follows: TMDL = £WLAs + £LAs + MOS The TMDL is a written plan and analysis established to ensure that a waterbody will attain and maintain applicable water quality standards. The TMDL is a scientifically based strategy which considers current and foreseeable conditions, utilizes the best available data, and accounts for uncertainty with the inclusion of a MOS value. Since conditions, available data, and the understanding of natural processes can change more than anticipated by the MOS, there exists the option of refining the TMDL for resubmittal to EPA. III. Background The Wilson Creek Watershed is located in southwestern Pennsylvania, occupying the southeastern part of Somerset County in Black Township. The watershed is found on the United States Geological Survey Rockwood and Murdock 7.5 minute Quadrangles. The area within the watershed consists of 8.0 square miles. Land uses within the watershed include woodland, cropland, pastureland, rural residential, inactive and reclaimed mining sites, and coal refuse piles. The Borough of Rockwood is located 3,000 feet south of the mouth of Wilson Creek, along S.R. 653. The headwaters can be reached by traveling on old S.R. 219, south of Somerset, to the traffic light at the intersection of old S.R. 219 and Garrett Shortcut; turn right on Garrett Shortcut Road and travel approximately three miles to the Shaffers crossroads intersection turning right for 500 feet. Wilson Creek is affected by pollution from AMD. This pollution has caused high levels of metals and, in some cases, low pH in the watershed. Currently there are no known operations that have National Pollutant Discharge Elimination System (NPDES) discharge points in the Wilson Creek Watershed. The discharges that are contributing to the degradation in the Wilson Creek water quality are associated with either long abandoned deep or surface mines and are not being treated. There are no active mining operations with WLAs in the watershed; however, three segments have future allocations included for possible remining operations. All remaining discharges in the watershed are resulting from abandoned mines and are treated as nonpoint sources. ------- PADEP treats each segment on the Section 303(d) List as a separate TMDL and expresses each TMDL as a long-term average loading. See the Wilson Creek TMDL Report, Attachment D, for the TMDL calculations. The Surface Mining Control and Reclamation Act of 1977 (SMCRA, Public Law 95-87) and its subsequent revisions were enacted to establish a nationwide program to, among other things, protect the beneficial uses of land or water resources, protect public health and safety from the adverse effects of current surface coal mining operations, and promote the reclamation of mined areas left without adequate reclamation prior to August 3, 1977. SMCRA requires a surface mining permit for the development of new, previously mined, or abandoned sites for the purpose of surface mining. Permittees are required to post a performance bond that will be sufficient to ensure the completion of reclamation requirements by the regulatory authority in the event that the applicant forfeits. Mines that ceased operating by the effective date of SMCRA (often called "pre-law" mines) are not subject to the requirements of SMCRA. Wilson Creek was on the 1996 Section 303(d) List of impaired waters and counts toward the twelfth year (2009) TMDL milestone commitment under the requirements of the 1997 TMDL lawsuit settlement agreement. The twelfth year milestone is the development of TMDLs, or delisting, for all remaining waters listed as impaired by AMD impacts on Pennsylvania's 1996 Section 303(d) List of impaired waters. Computational Procedure The TMDLs were developed using a statistical procedure to ensure that water quality criteria are met 99% of the time as required by Pennsylvania's water quality standards. A two- step approach was used for the TMDL analysis of impaired stream segments. The first step used a statistical method for determining the allowable instream concentration at the point of interest necessary to meet water quality standards. An allowable long-term average instream concentration was determined at each sample point for metals and acidity. The analysis was performed using Monte Carlo simulation to determine the necessary long-term average concentration needed to attain water quality criteria 99% of the time, and the simulation was run assuming the dataset was log normally distributed. Using @RISK2, each pollutant source was evaluated separately by performing 5,000 iterations of the model where each iteration was independent of all other iterations. This procedure was used to determine the required percent reduction that would allow the water quality criteria to be met instream at least 99% of the time. A second simulation that multiplied the percent reduction by the sampled value was run to ensure that criteria were met 99% of the time. The mean value from this dataset represents the long-term average concentration that needs to be met to achieve water quality standards. 2 @RISK - Risk Analysis and Simulation Add-in for Microsoft Excel, Palisade Corporation, Newfield, NY. ------- The second step was a mass balance of the loads as they passed through the watershed. Loads at these points were computed based on average flow. Once the allowable concentration and load for each pollutant was determined, mass-balance accounting was performed starting at the top of the watershed and working downstream in sequence. This mass balance or load tracking through the watershed utilized the change in measured loads from sample location to sample location as a guide for expected changes in the allowable loads. The existing and allowable long-term average loads were computed using the mean concentration from @RISK multiplied by the average flow. The loads were computed based on average flow and should not be taken out of the context for which they are intended. They are intended to depict how the pollutants affect the watershed and where the sources and sinks are located spatially in the watershed. A critical flow was not identified, and the reductions specified in this TMDL apply at all flow conditions. In addition to the above analysis, the WLAs for the NPDES permitted pit water treatment ponds were determined. Typically, surface mining operations include an open pit where overburden material has been removed to access the underlying coal, and this pit can accumulate water primarily through direct precipitation and surface runoff. The pit water is pumped to a nearby treatment pond where it is treated to the level necessary to meet effluent limitations. However, precipitation events allow intermittent discharges from the treatment pond. If accurate flow data are available for a treatment pond, they can be used to quantify the WLA by multiplying the flow by the best available technology (BAT) effluent limitations for treatment ponds. However, these flow data are typically not available. Alternatively, PADEP calculated a total average flow for the water draining to the pit using average annual precipitation, the area of the pit, and a runoff factor. Utilizing this value and BAT treatment pond effluent limits, the WLAs were determined. IV. Discussions of Regulatory Requirements EPA has determined that these TMDLs are consistent with statutory and regulatory requirements and EPA policy and guidance. 1. The TMDLs are designed to implement the applicable water quality standards. Water quality standards are state regulations that define the water quality goals of a waterbody. Standards are comprised of three components: (1) designated uses; (2) criteria necessary to protect those uses; and (3) antidegradation provisions that prevent the degradation of water quality. Wilson Creek has been designated by Pennsylvania as a cold water fishery with criteria to protect the aquatic life use, and the designation can be found at Pennsylvania Title 25 §93.9v. To protect the designated use as well as the existing use, the water quality criteria shown in Table 2 apply to all evaluated segments. The table includes the instream numeric criterion for each parameter and any associated specifications. Table 2. Applicable Water Quality Criteria Parameter Aluminum (Al) Criterion Value (mg/1) 0.75 Duration Maximum Total Recoverable/ Dissolved Total Recoverable ------- Parameter Iron (Fe) Manganese (Mn) pH Criterion Value (mg/1) 1.50 0.30 1.00 6.0-9.0 Duration 30-day Average Maximum Maximum Inclusive Total Recoverable/ Dissolved Total Recoverable Dissolved Total Recoverable N/A Pennsylvania Title 25 §96.3c requires that water quality criteria be achieved at least 99% of the time, and TMDLs expressed as long-term average concentrations are expected to meet these requirements. That is, the statistical Monte Carlo simulation used to develop TMDL WLAs and LAs for each parameter resulted in a determination that any required percent pollutant reduction would assure that the water quality criteria would be met instream at least 99% of the time. The Monte Carlo analysis performed 5,000 iterations of the model where each iteration was independent of all other iterations and the dataset was assumed to be log normally distributed. EPA finds that these TMDLs will attain and maintain the applicable narrative and numeric water quality standards. The pH values shown in Table 2 were used as the endpoints for these TMDLs. In the case of freestone streams with little or no buffering capacity, the allowable TMDL endpoint for pH may be the natural background water quality, and these values can be as low as 5.4 (Pennsylvania Fish and Boat Commission). However, PADEP chose to set the pH standard between 6.0 to 9.0, inclusive, which is presumed to be met when the net alkalinity is maintained above zero. This presumption is based on the relationship between net alkalinity and pH, on which PADEP based its methodology to addressing pH in the watershed (see the Wilson Creek Watershed TMDL Report, Attachment B). A summary of the methodology is presented as follows: The parameter of pH, a measurement of hydrogen ion acidity presented as a negative logarithm of effective hydrogen ion concentration, is not conducive to standard statistics. Additionally, pH does not measure latent acidity that can be produced from the hydrolysis of metals. PADEP has been using an alternate approach to address the stream impairments noted on the Section 303(d) List due to pH. Because the concentration of acidity in a stream is partially dependent upon metals, it is extremely difficult to predict the exact pH values which would result from treatment of AMD. Therefore, net alkalinity will be used to evaluate pH in these TMDL calculations. This methodology assures that the standard for pH will be met because net alkalinity is able to measure the reduction of acidity. When acidity in a stream is neutralized or is restored to natural levels, pH will be acceptable (>6.0). Therefore, the measured instream alkalinity at the point of evaluation in the stream will serve as the goal for reducing total acidity at that point. The methodology that is used to calculate the required alkalinity (and therefore pH) is the same as that used for other parameters such as iron, aluminum, and manganese that have numeric water quality criteria. EPA finds this approach to addressing pH to be reasonable. PADEP also has an alkalinity standard. Alkalinity (of a minimum 20 mg/1 calcium carbonate except where natural conditions are less) is related but not identical to pH. Alkalinity ------- is a measure of the buffering capacity of the water. Adequate buffering prevents large swings in pH with additions of small amounts of acid. Although many of the AMD-impacted streams are naturally low in alkalinity, available monitoring data does not always include upstream waters not impacted by AMD. As PADEP does not list waters for inadequate alkalinity, TMDLs are not being developed for alkalinity, but PADEP should monitor the waters for alkalinity and if, after these TMDLs are implemented, alkalinity is less than 20 mg/1 or natural conditions, PADEP should list the waters for alkalinity and develop TMDLs. 2. The TMDLs include a total allowable load as well as individual wasteload allocations and load allocations. For purposes of these TMDLs only, point sources are identified as permitted discharge points or discharges having responsible parties, and nonpoint sources are identified as any pollution sources that are not point sources. Abandoned mine lands were treated in the allocations as nonpoint sources. As such, the discharges associated with these land uses were assigned LAs (as opposed to WLAs). The decision to assign LAs to abandoned mine lands does not reflect any determination by EPA as to whether there are unpermitted point source discharges within these land uses. In addition, by approving these TMDLs with mine drainage discharges treated as LAs, EPA is not determining that these discharges are exempt from NPDES permitting requirements. To determine the WLAs for the NPDES permitted pit water treatment ponds, PADEP first calculated a total average flow for the water draining to the pit using average annual precipitation, the area of the pit, and a runoff factor. The WLAs were then calculated using this value and the BAT treatment pond effluent limits and were included in the mass balance along with the LAs. Once PADEP determined the allowable concentration and load for each pollutant, a mass balance accounting was performed starting at the top of the watershed and working downstream in sequence. Load tracking through the watershed utilizes the change in measured loads from sample location to sample location as a guide for expected changes in the allowable loads. PADEP used two basic rules for the load tracking between two ends of a stream segment: (1) if the measured upstream loads are less than the downstream loads, it is indicative that there is an increase in load between the points being evaluated, and no instream processes are assumed; and (2) if the sum of the measured loads from the upstream points is greater than the measured load at the downstream point, it is indicative that there is a loss of instream load between the points, and the ratio of the decrease shall be applied to the allowable load being tracked from the upstream point. Tracking loads through the watershed provides a picture of how the pollutants are affecting the watershed based on the available information. The analysis is performed to ensure that water quality standards will be met at all points in the stream. EPA finds this approach reasonable. Table 3 presents a summary of the allowable loads, LAs, and WLAs for the Wilson Creek Watershed. ------- Table 3. Wilson Creek Watershed Summary Table Parameter Existing Load (Ibs/day) TMDL Allowable Load (Ibs/day) WLA (Ibs/day) LA (Ibs/day) NFS Load Reduction (Ibs/day) NFS % Reduction WILSON12 - Wilson Creek upstream of all Unnamed Tributaries Aluminum (Ibs/day) Iron (Ibs/day) Manganese(lbs/day) Acidity (Ibs/day) 2.83 2.00 0.23 38.71 1.33 2.00 0.23 0.77 - . . - 1.33 NA NA 0.77 1.50 NA NA 11.39 53% NA NA 98% WILSON10 - Wilson Creek upstream of WILSON9 Unnamed Tributary Aluminum (Ibs/day) Iron (Ibs/day) Manganese(lbs/day) Acidity (Ibs/day) 173.21 36.89 33.18 1672.53 8.66 24.35 16.26 0.00 1.68 6.78 4.50 - 6.98 17.57 11.76 0.00 163.05 12.54 16.92 1634.59 95%* 34%* 51%* 100%* WILSON9 - Unnamed Tributary to Wilson Creek at mouth Aluminum (Ibs/day) Iron (Ibs/day) Manganese(lbs/day) Acidity (Ibs/day) 3.87 62.00 8.56 192.25 1.32 1.24 1.45 0.00 - - - - 1.32 1.24 1.45 0.00 2.55 60.76 7.11 192.25 66% 98% 83% 100% WILSONS - Unnamed Tributary to Wilson Creek at mouth Aluminum (Ibs/day) Iron (Ibs/day) Manganese(lbs/day) Acidity (Ibs/day) 1.24 1.59 1.06 17.71 0.26 0.52 0.56 0.00 - - - - 0.26 0.52 0.56 0.00 0.98 1.07 0.50 17.71 79% 67% 47% 100% WILSON? - Wilson Creek downstream of WILSONS Unnamed Tributary Aluminum (Ibs/day) Iron (Ibs/day) Manganese(lbs/day) Acidity (Ibs/day) 228.60 195.71 94.56 3170.75 20.57 43.06 30.26 0.00 1.68 6.78 4.50 - 18.89 36.28 25.76 0.00 39.95 78.28 39.77 1288.56 66%* 65%* 57%* 100%* WILSON6 - Wilson Creek at mouth Aluminum (Ibs/day) Iron (Ibs/day) Manganese(lbs/day) Acidity (Ibs/day) 305.33 147.97 108.17 3257.38 15.27 62.15 35.70 0.00 1.68 6.78 4.50 - 13.59 55.37 31.20 0.00 82.03 0.00 8.17 86.63 85%* 0%* 19%* 100%* NA = not applicable ND = not detected * Takes into account load reductions from upstream sources. Numbers in italics are set aside for future mining operations. PADEP allocated to nonpoint sources and point sources. There are no active mining operations in the watershed. Where there are active mining operations, Federal regulations require that point source permitted effluent limitations be water quality based subsequent to TMDL development and approval.3 In addition, PA Title 25, Chapter 96, Section 96.4d requires It should be noted that technology-based permit limits may be converted to water quality-based limits according to EPA's Technical Support Document For Water Quality-based Toxics Control, March 1991, recommendations. ------- that WLAs serve as the basis for determination of permit limits for point source discharges regulated under Chapter 92 (relating to NPDES permitting, monitoring, and compliance). Therefore, no new mining may be permitted within the watershed without reallocation of the TMDL. The Wilson Creek TMDL has allowed for future mining allocations on three segments with three mining operations in each segment. Additionally, no required reductions of permit limits are necessary at this time, as all necessary reductions have been assigned to nonpoint sources. 3. The TMDLs consider the impacts of background pollutant contributions. The TMDLs were developed using instream data, which account for existing background conditions. 4. The TMDLs consider critical environmental conditions. The reductions specified in these TMDLs apply at all flow conditions. A critical flow condition was not identified from the available data. 5. The TMDLs consider seasonal environmental variations. The dataset included data points from all seasons, thereby accounting for seasonal variation implicitly. 6. The TMDLs include a Margin of Safety. The CWA and Federal regulations require TMDLs to include a MOS to take into account any lack of knowledge concerning the relationship between effluent limitations and water quality. EPA guidance suggests two approaches to satisfy the MOS requirement. First, it can be met implicitly by using conservative model assumptions to develop the allocations. Alternately, it can be met explicitly by allocating a portion of the allowable load to the MOS. PADEP used an implicit MOS in these TMDLs by assuming that the treated instream concentration variability was the same as the untreated stream's concentration variability. This is a more conservative assumption than the general assumption that a treated discharge has less variability than an untreated discharge. By retaining variability in the treated discharge, a lower average concentration is required to meet water quality criteria 99% of the time than if the variability of the treated discharge is reduced. Additionally, calculations were performed using a daily average for iron rather than the 30-day average, thereby, incorporating a MOS. 7. The TMDLs have been subject to public participation. Public notice of the draft TMDL was published in the Pennsylvania Bulletin and the Daily American on January 9, 2008, to foster public comment on the allowable loads calculated. The public comment period on this TMDL was open from January 9, 2008 to March 19, 2008. A public meeting was held on January 24, 2008, at the Cambria District Mining Office to discuss ------- the proposed TMDL. No comments were received relating to Wilson Creek TMDL. Although not specifically stated in the TMDL Report, PADEP routinely posts the approved TMDL Reports on their web site: www.dep.state.pa.us/watermanagement_apps/tmdl/. V. Discussion of Reasonable Assurance Aside from PADEP's primary efforts to improve water quality in the Wilson Creek Watershed through reclamation of abandoned mine lands and through the NPDES permit program, additional opportunities for reasonable assurance exist. PADEP expects that activities such as research conducted by its Bureau of Abandoned Mine Reclamation, funding from EPA's §319 grant program, and Pennsylvania's Growing Greener program will help remedy abandoned mine drainage impacts. PADEP also has in place an initiative that aims to maximize reclamation of Pennsylvania's abandoned mineral extraction lands. Through Reclaim PA, Pennsylvania's goal is to accomplish complete reclamation of abandoned mine lands and plugging of orphaned wells. Pennsylvania strives to achieve this objective through legislative and policy land management efforts and activities described in the TMDL Report. Currently, there is no watershed organization interested in the Wilson Creek Watershed. It is recommended that agencies work with local interests to form a watershed group that will be dedicated to the remediation and preservation of these watersheds through public education, monitoring and assessment, and improvement. 10 ------- |