ACID MINE DRAINAGE POLLUTION CONTROL DEMONSTRATION PROGRAM

USES OF EXPERIMENTAL WATERSHEDS*

W. E . BULLARD**

ABSTRACT

The acid mine drainage pollution control demonstration program began in 1964 with selection of the site for Demonstration Project No. 1 near Elkins, West Virginia, in the headwater drainage of the Ohio River Basin. The project occupies 2 small adjacent watersheds, and covers 32 square miles. The program is jointly carried out by the Department of Health, Education, and Welfare and the Department of the Interior in cooperation with the State of West Virginia. The State of West Virginia is a participant, particularly with regard to legal aspects of the program. Objective of the program is to determine the relative effectiveness and cost of different acid pollution control and prevention measures, toward making recommendations applicable to a national control program. The measures to be tried will include sealing the mines against air, backfilling abandoned tunnels with mine wastes, diversion of surface drainage to prevent infiltration into the mines, concrete grouting to plug openings caused by settling of unsupported rock formations, chemical grouting to reduce soil permeability, and reclamation (by reshaping the contour and by revegetation) of areas grossly disturbed by strip mining. The study phase of the program includes installations for measuring stream flow and for automatic monitoring of temperature, pH, conduc-tivity, and oxygen content of stream flow; regular sampling at various points along the stream to determine acid load; iron and sulfate content, and nutrient content; biological observations on all elements of the aquatic habitat, some tests of adaptability of game fish to waters of different acidity, and a close cost accounting on all acid control measures. Similar information will be developed from Demonstration Project No. 2 under much different conditions .The program will be carried out to measure the effectiveness of the control measures. The expected return to normal may fake many years.

RÉSUMÉ

Le Programme à Démontrer le Contrôle de la Pollution des Fleuves Faite par les Drainages Acides des Houillères Utilise les Bassins Versants Expérimentaux.

Le programme à démontrer le contrôle de la pollution faite par les drainages acides des houillères a commencé en février 1964 avec la sélection d'un site pour le Projet de Démonstration No 1 près d'Elkins, West Virginia, dans le grand bassin du fleuve Ohio. Ce projet s'étend sur deux petits bassins adjacents avec une superficie totale d'environ 82 kilomètres carrés. Le, programme est dirigé par le Département de la Santé, l'Éduca-tion et le Bien-être des États-Unis; mais le Département de l'Intérieur aussi y participe. L'état West Virginia participe à l'aspect légal du programme. Le but est à décider de l'efficacité relative et des frais d'exploitation des méthodes différentes pour contrôler ou prévenir la pollution par les drainages acides, pour faire les recommandations utiles d'un programme national. Les méthodes que nous éprouverons inclurent le scellage des mines contre l'air, le comblement des corridors miniers abandonnés avec les déchets des houillères, la diversion des eaux de surface à prévenir leur infiltration dans les mines, l'injection du béton à obstruer les embouchures faites par l'enfoncement des structures rocheuses insoutenues, l'injection des composés chimiques à réduire la perméabilité du sol, et la réhabilitation et la revégétation des aires dérangées. Cette phase du pro-gramme qu'appartient à l'étude comprend faire les installations pour mesurer l'écoule-ment et pour la surveillance automatique de la température, de l'acidité, de la conduc-tivité, et de l'oxygène dissous dans les fleuves; l'échantillonage périodique à plusieurs postes le long des fleuves à déterminer la charge de l'acide, du fer et du sulfate, et des matières nutritives; les observations biologiques sur l'habitat aquatique; des essais sur

(*) Presented at the Symposium on Representative and Experimental Areas, Budapest, Hungary, September 30, 1965.

(**) Coordinator, Acid Mine Drainage Pollution Control Demonstration Program, Division of Water Supply and Pollution Control, Public Health Service, United States Department of Health, Education, and Welfare, Washington, D.C.

190

l'adaptation des poissons aux eaux des acidités différentes; et une comptabilité exacte pour toutes les méthodes de contrôle. Les renseignements similaires seront gagnés du Projet de Démonstration No 2 sous une situation bien différente dans l'état Pennsylvania. Les études continueront jusqu'à la qualité de l'écoulement et de l'habitat aquatique reviendront au normal ou à un niveau moins acide, probablement pas plus de dix ans.

Water resources have various aspects and properties. Some properties may directly pertain to water quality; distribution and circulation may significantly affect it. In turn, water quality is a measure of the utility of water resources. It is certainly logical to include water quality along with such characteristics as volume, flow, and location in any consideration of water resources. Such consideration has not always been given in watershed-wide studies and for that reason this paper is presented to describe experimental watersheds selected principally for water quality and pollution control studies.

HISTORICAL BACKGROUND

Early settlers in what is now the United States sometimes searched out seams of coal by tracing to their source the trickles of sour, discolored water found here and there in the coal regions. Some of these acid contributions to streams occurred naturally long before man's entry upon the scene. They increased as the country grew and coal mining became a major industry, exposing more and more sulfur-bearing material to oxidation by the air and leaching by percolating rain water and snowmelt.

The need for control of acid pollution from mine drainage has long been recognized. Mine sealing some thirty years ago was in many instances effective in reducing the acid flows. Within three years, acid load reductions of from 25 to 80 percent were observed. However, the seals were not maintained and many of the mines were reopened in answer to the demands of World War II. Regionally, acid pollution is estimated ot have increased from 2,700,000 tons annually before the sealing program to more than 3,500,000 tons today.

A program to demonstrate procedures for and results of acid mine drainage control was begun late in 1963. The program is a joint venture of the United States Department of Health, Education, and Welfare and of the Department of the Interior. The water pollution control and natural resources agencies of the States where demonstration projects are located also participate.

Essentially the program is a series of experiments on watersheds representing pro-blem situations in water quality. It calls for treatments to be applied that change the situations, effects of treatment to be observed and described in both biological and chemical terms, correlations to be developed and conclusions drawn as to the effectiveness and applicability of the treatment in the given and in similar situations.

DEMONSTRATION PROJECT NO. 1

Selection and Establishment

The site for the first demonstration project comprises two small watersheds near Elkins, West Virginia, draining into the Tygart Valley River in the upper Monongahela and Ohio basins. The watersheds lie side by side; one, Roaring Creek, covers about 28 square miles (72 square kilometers) and the other, Grassy Run, about 4 square miles (10 square kilometers). It was necessary to include both because a subsurface network of coal mine passageways and galleries interconnects and mixes the percolating drainage waters. For purposes of accurate measurement the congruent surface and subsurface drainages are required.

191

Physical Characteristics

The site is a roughly rectangular area about twice as long as wide, at elevations from 1 850 feet (564 m) at the mouth of Grassy Run to 3 660 feet (1116 m) on the southeast rim of the Roaring Creek watershed. (See map, Fig. 1). The drainage is north in Grassy Run and in the Roaring Creek mainstem, west in most of the Roaring Creek tributaries. The topography is hilly and rough. The mines underneath present a network six miles (10 km) across and drain toward the northwest along the gentle dip of the coal seams.

Demonstration Project

No. i

Randolph County, Wast Virginia

MtLES

(S) A

O

The underground coal mine installations are located near the mouth and in the lower central parts of the watershed at or near stream levels. Stripmines have cut notches around the higher hills in the basin interior, and around the noses of the ridges on parts of the basin rim. Four discrete coal beds have been worked by underground stripmining. As the map shows, the area of stripmine disturbance amounts to about 5 percent of the basin area, or a little more than 900 acres (about 370 ha) at present.

192

A few small farms are located along the streams and on the ridges around the rim, about two dozen all told. Total area under cultivation is not large; but cattle graze over some of the forest area of the watershed. The cover is predominantly hardwood forest, with few openings. The basin has been logged over several times, but at present only a small amount of timber is cut and that primarily for mine props. One county road and four coalhaul roads serve the watershed, and a U.S. highway runs along the northwest r im.

Geology of the area is relatively uncomplicated. The principal coal seams are the Sewell and the Lower and Middle Kittaning; they are separated by sandstones and shales. In the immediate locality there has been little folding of the formations; most are fairly flat and dip toward the north. The layers of rock directly underneath and between the coal beds, and the coal itself, contain pyrite and marcasite, the sulfur-bearing source materials of the acid problem. The sandstone and shale strata above the coal are in this area quite free of sulfur. Some of the formations near the surface are fractured from settling after removal of the supporting coal in the worked seams.

Climate of the area is moderate and humid, with spring and summer rainfall predominant. Average annual rainfall is about 48 inches (120 cm). Summer temperatures have reached 100 °F (38 °C), although the July average is 70 °F (21 °C). Winter temperatures have dropped as low as — 28 °F (—33 °C), with the average for January 32°F (0°C). Snow is common, averaging 70 inches (180 cm) for December to March, inclusive. High intensity rainfall up to 2 inches (5 cm) per hour occurs with a frequency of once a year. The frost-free growing season is 160 days, from early May to mid October on the average.

To locate all openings where air and water can enter the subsurface mine workings a survey was made by the Bureau of Mines of the Department of the Interior first by inspection of aerial photos and old mine maps. Later the watershed was covered oh foot, back and forth in narrow zones, to find any openings not referenced on the maps and the fissures created by settling of overlying rock when coal was removed. Several of the mine-seal plugs of thirty years ago were found on this field check. The old pro-gram located the openings to be plugged in cold weather by the tell-tale condensation of vapor in the warm air coming out of the mines. Lack of vapor was taken as an indication later that all holes had been found and effectively sealed. The new survey applied the same test as well as aerial and ground reconnaissance methods to find some 625 openings.

Immediately after the site selection, a survey was made to establish a network of stream sampling stations and locate all sources of acid drainage. Aerial photographs covering the study watershed on a scale of 1 : 12,000 were taken in April after the snow had melted, but before the trees and shrubs came into leaf. Roads, stream courses, and mine workings showed plainly at this season. The photographs were used in making topographic and mosaic maps and in determining the extent of stripmining operations.

Simultaneously with location of the stream sampling stations, the U. S. Geological Survey of the Department of the Interior established permanent gaging stations near the mouths of both Grassy Run and Roaring Creek. The gage shelters also house automatic monitors (1) installed by the U.S. Public Health Service of the Department of Health, Education, and Welfare. Stream flow level, water temperature, specific conductivity (an indicator of dissolved, inorganic solids), pH, oxidation-reduction potential, and dissolved oxygen are recorded automatically at both stations. In addition, water samples are collected at 132 points within the watershed for analysis to determine p H , temperature, total potential acidity (2), alkalinity, specific conductivity, total iron, total sulfates, aluminum, ferrous iron, and total hardness on a twice-weekly basis; chlorides are determined occasionally. The Geological Survey is also collecting samples

193

to determine amount of suspended sediment carried by the two streams near their mouths. Estimates of erosion rates will be based on the sediment load observations.

Studies of the streams as aquatic habitat were made in various reaches having different levels of acidity. In the most acid portions, where the pH was 2.5 to 3.5, the only life form found was an alga (Ulotkrix zonata) which grew in long, dark green ropes from rocks in the stream bottom. Populations of native brook trout (Salvelinus fonti-nalis) were discovered in the small headwater tributaries where there is as yet no acid pollution. The studies were of two kinds; — one from the standpoint of water quality indicators, the other from the standpoint of fish habitat. The acid load and the iron deposits have made the aquatic habitat unusable for most life forms, and the precipi-tated iron compounds have left telltale red deposits on rocks several miles down the Tygart Valley River which receives the acid waters of Roaring Creek and Grassy Run. Studies by the U. S. Bureau of Sport Fisheries and Wildlife include observations on pH and stream temperature in those reaches where no fish are found. Where fish occur, pH, temperature, specific conductivity, total hardness, alkalinity, meta- and ortho-phosphate, and occasionally total iron are measured. (3)

vw I

' $ % • • \ » ' \

'•-.iMV-i

~ • • - 5 - -1 * - • • •

• - . . • * . . •> • y . • • • ' . . . . - . — . .

- ^ * •".--* i " ,

Core drilling was done at 17 sites and churn drilling at 11 others to guide mapping of the geologic structure, to locate pyrite and marcasite strata, and to furnish informa-tion on cracks in the rock layers and on groundwater location and movement. Samples were collected from "gob" piles (waste material from the underground mines) and stripmine spoil banks for analysis of acidity. Where there were no settling cracks in the overlying rock it was observed that ground water stood in the boreholes.

Analysis of the spoil (fine broken rock material) from the "gob" piles and spoil-banks indicated a good deal of acidforming material at the surface exposed to the air. Highly acid water trickles from beneath a "gob" pile near one of the mine adits where

194

mining is still going on. Water ponded against the stripmine highwalls or draining from the barren spoilbanks is nearly everywhere quite acid.

From observations of groundwater movement, it is suspected that water is percola-ting from tributaries of Roaring Creek through the mine workings and coming out charged with acid into Grassy Run. Stripping operations and auger-drilling into strip-mine highwalls have broken through into the old underground workings here and there, and let surface water drain directly into the mine. (See Figures 2 and 3).

Installation of Acid Pollution Control Measures

After a year of measurements of streamftow volume and quality to establish a base for comparison, installation of various pollution control measures will begin. A variety of methods, both proven and experimental, will be applied both on the surface and underground. It is anticipated that two years will be needed to complete them. Mean-while the stream measurements and aquatic habitat studies will continue.

One important measure will be air-sealing the underground passageways and galleries to cut off access of oxygen to exposed faces of formations bearing pyrite and marcasite. This may be accomplished in a number of ways — by putting in wet masonry " curtains " or walls to close off the openings and blowing the passageways full of nitro-gen-filled plastic bubbles; by coating tunnel and gallery walls with a chemical to form a barrier against oxidation; and by injecting gels to plug settling cracks.

Seals to cut down the surface water infiltration into the deep mines and thus reduce leaching and transport of sulfate compounds is another important measure. Some water seals will result in the flooding of old workings and hopefully will inhibit acid formation as long as the water level is maintained. The use of chemical grout to plug cracks, make soil impermeable, and bind sulfur will retard both water and air

195

movement. In many places it will be necessary to divert water away from settling depressions and stripmine highwalls. Some of the diversion channels and perhaps some permeable sections of the main stream itself will require lining to prevent infiltration of the surface water. The lining may be compacted clay, bentonite, concrete, or even metal. To seal cracks, concrete grouting as well as chemical grouting may be used.

The "gob" piles near the mine entrances contain large amounts of acid-forming materials and need treatment. Some may be used to backfill abandoned mine tunnels or stripmine pits, but most will have to be treated in place. Treatment will include diversion of water away from the pile base, spraying or injecting the piles with chemical grout, and "roofing" over the pile surfaces with clay to reduce infiltration of rainwater and snowmelt.

Grouting—employing chemicals, gels, or concrete—will be used to reduce per-meability of porous soils and of hard-to-get-at fissures. Quite often, the settling cracks occur in locations difficult of access, requiring extensive ground preparation before filling and compaction. Piping grout to these locations may well prove quicker and simpler and requires little or no ground preparation. Certain chemicals such as sodium silicate, on drying, form a sealing " skin " or coat in the cracks they penetrate. Also as a surface cover they tend to bind or tie-up the sulfur compounds in such a way as to make them unavailable for oxidation, leaching, and acid production. Grouting can be used to put neutralizing as well as stabilizing and sealing materials into the soil and rock formations.

Reshaping the stripmine spoilbanks and highwalls is necessary to bury exposed pyrite-bearing rock and to keep surface drainage away from it. Particularly where surface operations have broken through into underground workings, as is the case at many points within Demonstration Project No. 1, there is a definite hazard that surface waters may drain down into the mine workings. Settling cracks along the highwalls, sometimes extending back fifty yards or more, also expose acid-producing material to percolating water and air. The spoilbanks need to be sloped up against the highwall, covering exposed strata where acid could form, and, as much as possible, burying acid-producing rock fragments in the spoil material itself. The new surface then must be compacted to speed up runoff to the main stream channel draining the area. Sections of the stream channel itself may also need reshaping and grading.

A good vegetation cover is desirable to prevent soil erosion and as an organic buffer against acid formation. Sediment and turbidity are pollution problems often associated with mining operations, though in the coal-mining areas these problems are generally overshadowed by the acid pollution. Experience in revegetation of spoilbanks by various public and private agencies (4), and research by the U. S. Forest Service (5) have determined for soils and spoilbanks of subsoil materials what species of trees and shrubs will succeed in a variety of situations of acidity, drainage, and exposure to sun and wind. However, the lower limit for successful establishment of vegetation so far as acidity is concerned is about pH 4.0, and survival is not very good. High acidity in itself is not toxic, but seems to interfere with nutrient uptake. Demonstration Project No. 1 has some areas of greater acidity than pH 4.0 and borderline areas of up to pH 4.5. It is proposed on these areas to add finely crushed limestone as a soil amendment to raise the pH and promote the establishment of a good vegetation cover. There undoubt-edly will be areas where a quick cover crop of grass and legumes will be used to bind the soil surface immediately, and perhaps to provide forage instead of forest. In some areas there may be materials other than limestone available to stimulate vegetation establishment, e.g., brush chips, sawdust, sewage sludge. These will be tried where they are available and can be applied at low cost.

It has been found that forest litter and the development of humus in the soil tend to reduce acid formation. Since forest cover provides a greater bulk of organic material, planting trees is preferable in the long run to planting brush or seeding grass. The species most adaptable for the very acid sites include black locust (Robinia pseudacacia),

196

northern red oak (Quercus rubra), and a number of pines native to or commonly planted in the region. (6) On less acid sites, useful species include bur oak (Q. macro-carpa), chestnut oak (Q. prinus), green ash (Fraximis Pennsylvania), white ash (F. americand), sweetgum (Liquidambar styraciflua), sycamore (Platanus occidentalis), silver maple (Acer saccharimtm), and yellow poplar (Liriodendron tulipifera). The pines may be planted in pure stands, but for the deciduous hardwoods mixed plantings are preferable.

Acid control installations may include such special strucutres as levees and dams to confine and create ponds. Work in eastern Ohio has demonstrated that flooding pyrite-bearing materials to a depth of four feet or more may be as effective in preventing acid formation as burial of the material. Creation of ponds also will enable controlled studies on different species,of fish to determine their adaptability to various levelsof acidity and iron compounds. In other States, attractive recreation areas and a good sport fishery have been developed through spoilbank reclamation after stripmining. It is hoped that similar developments will prove feasible here.

Observations and Studies

Most of the water sampling on the project area consists of "g rab" or "d ip" samples taken along the stream and at numerous places where sizable mine outflows occur. At the streamgaging stations, automatic stage recorders and automatic water quality monitors continuously record several of the characteristics previously mentioned. The monitors are similar to that shown in Figure 4. The bottom compartment of the monitor contains the sensing probes for measuring the parameters noted; these probes are immersed in a flowing bath pumped continuously from the stream. Meters providing direct instantaneous readings from the probes are shown on the face of the central or analyzer compartment which contains the bulk of the wiring and which amplifies and converts the impulses from the probes into information for the recorder. In the top compartment is located the strip-chart analog recorder that marks on a timed-moving chart the readings at half-hour intervals. The chart recorder can be replaced by a digital output recorder which records on a paper tape, or by a transmitter that tele-meters directly to some central location serving a number of projects where information can be recorded in digital form for use in a computer.

Studies in hydrology will provide data on streamflow regime and permit the relating of flow volume to acid load. They will also provide a measure of the stabilizing effect of the control measures on streamflow and quality as the project work progresses.

The geochemical studies began with a field study of the local geology, analysis of drill core samples, and collection of groundwater samples from the drill holes. The cores showed the distribution and thickness of the coal beds and the associated shales and siltstones that contain finely disseminated particles of pyrite. Observations on the coal outcrops often revealed yellow sulfur masses. Analyses are made on groundwater samples to determine bicarbonate, carbonate, sulfate, chloride, fluoride, nitrate, dissolved solids content, calcium, carbonate hardness, permanent hardness, specific conductance, and pH. A few of the samples have also been analyzed for aluminum, iron, manganese, immediate acidity, and potential free acidity. Some measurements, as for pH, conductance and temperature, are made at the time the samples are collected in the field. Other samples are shipped for analyses to a central laboratory of the U. S. Geological Survey, using standard analytical methods (7).

Aquatic biology is a subject of interest from a number of viewpoints. The relative sterility of a stream in lifeforms, or the types of life-forms found, is an indicator of acid conditions. They are also indicators of the condition of the aquatic habitat for fish, particularly for food fish and game fish. And as indicators of acid conditions, these biologic signposts also indicate the quality of the water for use by man. The biology studies, began simultaneously with the water sampling, will be continued

197

throughout the life of the project to determine the changes and the sequence and rate of changes that take place as the acid pollution abatement measures become effective.

As part of the program, small ponds will be created in some of the stripmine cuts to provide locations for studying the adaptability of fish to different degrees of acidity and varying amounts of iron and other mineral compounds. (Ponds will be located where there will be no hazard of seepage into the underground mine workings). Test

fish species will include brook trout (Salvelinus fontinalis), brown trout (Salmo trutta), bluegill sunfish (Lepomis macrochirus), and smallmouth bass (Micropterus dolomieu).

198

The pondwater will be sampled and analyzed for nutrients, acidity and toxic materials at regular intervals ; and pond biology will be observed in the same way as that in the streams. Results and conclusions from this study will show the potential for recreation development based on the attraction of a sport fishery.

Appraisal of Control Measures

Determining the relative effectiveness and the cost of various measures applied to prevent or control acid production and stream pollution is a major objective of the demonstration program. The effectiveness will be learned from the biological studies and the water quality monitoring and sampling as the dissolved load lessens, the aquatic habitat improves, and fish return to the once polluted streams. Some answers may come very soon, others must wait until stream conditions stabilize and the project is ended. Effectiveness may be stated in terms of both acid load and aquatic habitat, as well as in terms of the stream water's usefulness for various consumptive purposes.

Beginning with the planning stages, careful accounting was and will be kept on the costs for each step from the primary survey through final inspection and acceptance of completed pollution control work. This phase of the demonstration project was considered sufficiently important to warrant establishment of a special accounting section. The cost accounting findings will be used to help judge the measures to recom-mend for a broad regional program, based on their rapidity and magnitude of reduction in acid pollution per unit cost.

PROSPECTS FOR THE FUTURE

Because a wide variety of conditions and problems must be met in any general acid pollution control program throughout the coal mining region, it would be well to establish at least a dozen projects to demonstrate control measures under differing conditions of climate, geology, topography, streamflow regimes, underground water movement, coal mining methods, and acid production. Each project site should comprise a complete watershed above and below ground and the work for each would more or less follow that for Demonstration Project No. 1.

SUMMARY

Experimental watersheds are useful specifically for water quality studies and for hydrologie studies generally. Under the acid mine drainage pollution control demonstra-tion program several projects, each on its own experimental watershed, are being esta-blished. These projects involve collection of hydrologie and water quality data on both surface and underground water and of biological observations on the aquatic habitat. They also involve study of geology, and of iron and sulfur chemistry. They include the application of a variety of physical and chemical, biological and perhaps bacteriological measures aimed at changing the hydrologie regime and at upsetting or counteracting certain chemical sequences. The final goal is to develop the least costly and most effective methods for combatting stream pollution from sulfuric acid draining from coal mines. There are many thousands of miles of acid-polluted streams and hundreds of thousands of acres of disturbed lands contributing the acid. The problem needs immediate attention. As to policy, the government does not wish to prevent use of a resource nor interfere with its development; but rather to find means of ensuring that use and development of one resource—in this case, coal—does not restrict or damage use or usefulness of other resources such as water and fisheries which may be of equal or greater value.

199

REFERENCES

C1) ORSANCO equipment; designed by Ohio River Valley Water Sanitation Commission.

(2) Determined by the hot phenolphthalein method described on p. 340, American Public Health Association, American Water Works Association, and Water Pollution Control Federation joint publication, 1960, "Standard Methods for the Examination of Water and Wastewater," 11th edition.

(3) Measurements of stream pH and temperature are made at the time of sampling; other analyses are made in the nearby Bowden hatchery laboratory of the U.S. Bureau of Sport Fisheries and Wildlife of the Department of the Interior.

(4) Coal Industry Advisory Committee, Ohio River Valley Water Sanitation Commission, March 1964. "Principles and Guide to Practices in the Control of Acid Mine Drainage. "

COLLIER, C. R.,et al., 1964. "Influences of Strip Mining on the Hydrologie Environ-ment of Parts of Beaver Creek Basin, Kentucky. " (£/. S. Geological Survey Professional Paper 427-B).

Tennessee Department of Conservation and Commerce, April I960. "Conditions Resulting from Strip Mining for Coal in Tennessee."

Pennsylvania State University Extension Service, 1963. "Strip Mine Spoil Reclamation. "

G.A. LIMSTROM, March 1964. "Revegetation of Ohio's Strip-Mined Land." In : The Ohio Journal of Science, vol. 64, No. 2, " A Symposium of Strip-Mine Reclamation. "

(5) BOYCE, S.G., and NEEBE, D.J., November 1959. "Trees for Planting on Strip-Mined Land in Illinois. " (Central States Forest Experiment Station Technical Paper 164, U.S. Forest Service).

G.A. LIMSTROM, February 1960. "Forestation of Strip-Mined Land in the Central States." (U.S. Department of Agriculture Handbook No. 166).

(G) Jack pine (Pimis banksiana), loblolly pine (P. taeda), pitch pine (P. rigida), red pine (P. resinosa), shortleaf pine (P. echinata), scrub pine (P. virginiana), Scotch pine (P. sylvestris), and eastern white pine (P. strobus), according to LINSTROM, G.A., February 1960, "Forestation of Strip-Mined Land in the Central States," U.S. Department of Agriculture Handbook No. 166.

(7) See RAINWATER, F.H., and THATCHER, L.L., 1960. "Methods for Collection and Analysis of Water Samples. " (U. S. Geological Survey Water Supply Paper 1954).

200