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AMD Discharges
Active and Inactive Mines in Pennsylvania
EY 1999
The purpose of this study was to collect and characterize water quality and flow data on a sample of permanent program surface mine and coal refuse pile permits with long-term pollutional discharges. In the study, quality and flow data was collected and both field and file reviews were conducted on the sample permits.
Background:
The Pennsylvania Department of Environmental Protection (PADEP) has identified the occurrence of permanent program (primacy) permits with pollutional discharges. To obtain information on the type and extent of these discharges, the Harrisburg Field Office (HFO) compiled an inventory (Acid Mine Drainage Inventory (AMDI)) of data available from PADEP databases. That inventory, which contains data on 500 permits, was created by digitizing printed reports of sites with discharges. The printed reports were provided at various times between 1995 and 1999 by PADEP. Not all of the data elements were available for all permits (See, Meta Data Report, EY 1999, Harrisburg Field Office).
To assess the current validity of data in the inventory, the annual workplan included field and file reviews of a samples of different categories of permits identified in the inventory. This study reviewed active and inactive surface mine and refuse pile primacy permits with pollutional discharges. Updated data on bond forfeiture and underground mine permits was collected under separate reviews. Data was collected to update current conditions of the previously identified discharges and to create a data base containing water quality and flow information on those active and inactive permits. The intent is to further develop the existing inventory database containing the active and inactive sites, and to characterize the type and extent of AMD pollution on those sites.
Summary of Findings:
- The average flow of the discharges in this study for refuse piles was about 600 gpm.
- The average flow of the discharges in this study for surface mines was 24 gpm.
- The average acid load from refuse piles reviewed was about 40 times greater than the average active and inactive surface mine in this study.
- The average iron and manganese load for refuse piles reviewed was about 400 times greater than the average active and inactive surface mine in this study.
Recommendations:
- The Field Office should continue field verifying and updating the remaining active and inactive permits with pollutional discharges in the existing database and characterize Acid Mine Drainage (AMD) discharges on those sites.
Data Presentation and Discussion:
Data in OSM’s compilation of PADEP information, identifies a total of 1999 active/inactive surface mine and refuse pile permits with AMD discharges. Of those, basic water quality data was available in previous databases for 77 permits totaling 124 discharges. OSM’s database had no water quality data on the remaining 122 permits. For this evaluation period, 27 permits were selected for inspection to gather discharge information. Since there was very little discharge information available for refuse piles, 8 refuse permits were selected for review. The other 19 permits were surface mines randomly selected for this sample.
The study data presented below are divided into two general sections. The first section contains detailed information pertaining to the permits inspected by HFO under this review. The second section provides general information concerning the all of the 100 active and inactive permits where HFO now has information on the pollutional discharges.
Study Permits: Of 27 permits selected for HFO inspection, 23 had discharges flowing at the time of inspection. The remaining four permits had either had no post-mining pollutional discharges (three permits), or no pollutional flow at the time of the inspection (one permit) due to drought conditions. It should be noted that 1999 summer drought conditions appeared to result in no-flow situations at several other discharge points on two permits. The information collected on the 23 permits examined the discharges associated with eight refuse pile permits and 15 surface mine permits. The refuse pile permits were located in Butler, Cambria, Greene, and Indiana County and contained a total of 11 discharges. The surface mine permits were primarily located in Somerset and Clearfield Counties and contained a total of 31 individual discharges.
This evaluation found that the 23 permits inspected contained 42 individual discharges, of which, 39 were receiving treatment. Three of the 39 treated discharges were being treated through passive treatment, with the remaining 36 treated with a variety of chemical treatment systems. Of the 39 discharge flows being treated, information during HFO inspections show that 31 have no impact on the receiving stream after treatment. Seven discharges have no more than minor impacts, while one is significantly impacted the receiving stream. HFO inspection information also determined that 20 of the discharges would have a significant impact on the receiving stream if treatment were stopped. Ten discharges would have a moderate impact if treatment were stopped and the remaining nine discharges would have minor impact on the streams if treatment were stopped. Of the 4 untreated discharges, 3 have a significant and one a minor impact on the receiving streams. These results are reflected in Appendix A.
Cumulative Permit Information: As discussed under Methodology, HFO identified 199 post-primacy permits with discharges, with basic water quality data from previous databases providing information for 77 permits containing 124 discharges. While the pre-existing information did not contain an analysis of the severity of impacts on streams, it did contain information on the flow and chemical nature of each discharge. Addition of the information on the 23 permits (containing 42 sampled discharges) brings the total number of permits with discharge data to 100 (total 166 discharges). The 100 permits are composed of 9 refuse pile permits and 91 surface mine permits. The information collected under this review allows some general observations on refuse piles and surface mines, and the overall environmental impacts.
The information for active and inactive sites indicates that when compared to surface mines, refuse piles generally produce a discharge with higher iron impacts. Surface mines, however, appear to have higher acidity and manganese levels (B-1). Cumulative discharge information also indicates that the average pollutional discharge from a refuse pile produces significantly more pounds of pollutants per day than the average surface mine discharge (B-2). In general, the average total acid load from a refuse pile is forty times greater than the acid load of a surface mine. In addition, the average total load of the remaining pollutants (iron and manganese) are 400 times greater than that of surface mines. Refuse piles clearly impose a disproportionate impact and treatment liability when compared to surface mines (Table 2). When compared to surface mines, the pollution load, cost to treat, and the treatment trust fund requirements are much greater for an average discharge. The average acid load from refuse piles reviewed was 40 times greater than the average surface mine.
It is noted that the total pollutional discharge load for Greene County is significantly increased by two refuse piles with flows exceeding 3000 gallons per minute.
Methodology:
During the inspections and file reviews, the "Mine Evaluation and Inspection Report" (MEIR), "Mine Drainage Inventory" (MDI) form, and the "Discharge Data Sheet" (DDS) were completed for each site. The forms MEIR and MDI were completed for each inspection, and the DDS was completed for each discharge (some sites had multiple discharges). The MEIR forms were input to the OSM I&E Tracking System by the inspectors. The MDI and DDS forms (attached) were input into a Microsoft Access database designed for this purpose. Field office staff input data on the MDI and DDS forms.
For comparison purposes only, treatment costs were (table 2) estimated using a formula from Acid Mine Drainage Control and Treatment - Second Edition, Chapter 23, Compiled by Jeffrey G. Skousen and Paul F. Ziemkiewicz. The formula multiplies the flow of the discharge in gallons per minute, times the tons of acid generated by the discharge per year. The tons of acid per year is then multiplied by a conversion factor ("Acid Mine Drainage Control and Treatment" (Skousen and Ziemkiewicz), Table 1, pg. 238) to determine the number of tons of treatment chemical required by year. The table also provides the 1996 costs of treatment chemicals at both bulk and normal rates.
The cost calculations in this report use the average conversion factors (.57) and average bulk reagent costs ($496) for anhydrous ammonia and caustic soda. These treatment chemicals were chosen due to their relative low set up and maintenance costs.
The formula for calculating the estimated annual treatment for a discharge was:
flow * acidity * .0022 * .57 * $495.00
The cost estimate if for reagent to treat acid discharges on and does not consider the treatment of alkaline or manganese discharges. Costs for maintenance, construction and sludge disposal for treatment facilities are also not considered.
Appendix A - Harrisburg Field Office Study Permits Summary
