First Report of the I Nter- Departmental Committee on Surface

First report of the I nter- Departmental Committee on Surface

Coal Mining of Alluvial Lands of the Hunter Valley. EV I p1R 1USR1ES I ABOI 9648 I I I I I SURFACE COAL MINING ALLUVIAL LANDS I HUNTER VALLEY I I I I I 114 I j_jBpAFkY I I I I I I 1 I I I I 1 FIRST REPORT I OF I TUE INTER-DEPARThIENTAL COMMITTEE I ON SURFACE COAL MINING OF ALLUVIAL LANDS I OF I THE HUNTER VALLEY I I I 1

May, 1980.

AO I, MiNUTE PAPER i PAPERS:- M76/4113 SUBJECT:- Buchanan Lernington Colliery cn Borehole Collieries Pty.Ltd. I Application to extend open cut coal mining operations into the alluvial lands of the Hunter River Valley.

Attention is invited to my within Minute dated 25th November, 1980 Wherein I discussed the subject application and the report by the Inter-Departmental I Committee and made certain recommendations in respect of the proposal. In accordance with approval dated 6th March, 1981, herein, The Minister wrote to The Hon.J.R.Hallam M.L.C. Minister for Agriculture, by letter dated 9th I March, 1981, copy herein, and sought Mr. Hal1's views on the proposal. In his reply dated 23rd July, 1981, herein, Mr. Nallam advised that he agreed with the subject proposal subject to;-

l. I it being stressed that the project is an a demonstration mine, experimental mine and not

2. until the results of the experimental mining had been evaluated, no further I approvals for surface coal mining on alluvial lands will be granted.

Items 1 & 2 above, have been covered in the letter to the company as recommended for despatch in my beforementioned Minute. Also, in such minute, it was recommended I that Departmental records be noted in accordance with item 2. The contents of Mr. Hallam's letter do not offect ift my minute dated 25th November, I 1980 and consequently the recommendations contained therein are submitted for consideration and approval. it. is however, further recommended that The Hon.J.R. Hallam be advised, under the hand of the Minister, in terms of the attached draft J letter. I Principalf f i c er, Coal Titles Section ----- I J 6- .- /

Submitted

i I FOR AFROVAL. I - I S WDER BEGRETAUY, 1 - - ZI7 /4 113 I IiH I Dear Nr. rallam,

I cknowledcji, with tln)c, receipt of your letter dated 23rd July, 1081, I (your reference P1.78/fl (6I!€)) wherein you agreed that an exj'ericental curface coal silning project should be llo.d to proceed Jr. tie al1uvi1 fl.t of the hunter ValleY. I decire to inforn you that I have I now apr)rov.d of c,pen cut nlnincj oI'ertjonc I,cinri carried out w1thi tat pert of the Iuel.anan Leoington Colliery s y blue e'39ing on tIo attached dlayra;r,, ubjcct to Aririexure A Copie2 the Condition0 set out on of th€. planc referred to in COnlition Vo. I of lflnexure I are attacI•1 for your information and as8itance

It too leen j'ointe1 out to tie cor.p.any that tie pro ned operat1 eper1i' utal one, only, and tiat, until the recul to have 0 lo a trial ['ten I evalu t d, no further approvale for rurface coal adequately irininq of the alluvial fiats viii be rantcc. I aere that, iLoujd the or.eratjon ho eucceouful, future applictj05 to carry out curfact. tlnin; in thare arean be conhered, aeparately, by the Intcr-DCL.arbTefltal Cor.jttee.

rurirci the courae of the operation it 18 propocd that the Coosmittee, together vith the District Inapector of Collieries, viii undertake certain lonitoring functions to ensure corpliance with the conditiOns of my approval and to ac&eso their effectiveri or likIy effectjvene If considered necessary, or dcIraL1e, in iicht of experience and knoviarige gained as nininq prcxJrcoes, I may, followjnq recomndatjont frcr the Coraittee, vary the conditjos of ny approval during the courne of the operation. i will keep you inforaed of future developentL.

Yours faithfully,

'inhiter for 'inerni P

The [ion. J.p Ilallan, 11ni5te for i3r1cu1ture, 4-- e1l nuilding, flawson Place, I EYDNEy. 2000

I I I I

1 SURFACE COAL MINING OF ALLUVIAL LANDS I IN THE HUNTER RIVER VALLEY Discussions early in 1978, between the Director-General of

I Agriculture and the Under Secretary of the then Department of Mines

(now the Department of Mineral Resources), led to invitations being ex-

L tended to four authorities to make officers available to serve on a

Committee which would examine and report on certain aspects of the feasi-

bility and likely effects of surface coal mining in riverine alluvial

lands in the Hunter River Valley. The authorities and the personnel who

have either served on the Committee from time to time, or attended

Committee meetings as observers to assist in its work, are:

Department of Agriculture

Dr. S. Grimniett, Messrs G.D. Koha, D. Toohey.

I Soil Conservation Service of New South Wales

Messrs D. Longworth, J. Hannan, J.M. Logan, R. Irwin.

Water Resources Commission

Messrs J.M. Blainey, B.W. Baker, D. Roberts, G. Gates. I Department of Mineral Resources Messrs W.N. Burton and D. Probert (Convenor) Li This is the Committee's first report. I

I (Sgd) G.[).ahn lv. - I (Sgd) '-diMjLogan 1 (Sgd) B.W. Baker (Sgd) D.H. Probert CONTENTS

Page I

TERMS OF REFERENCE 1

CONCLUSIONS AND RECOMMENDATIONS 5 I INTRODUCTION 8

DEFINITION OF ALLUVIAL LANDS 9 I COAL MINING IN ALLUVIAL LANDS 9

Federal Republic of Germany 9 I German Democratic Republic 9 United States of America 10 Australia 10 I Summary 11 LEGISLATIVE CONTROL ON MINING IN ALLUVIAL LANDS 11 I RESOURCES OF THE UPPER HUNTER VALLEY ALLUVIAL AREAS 12 WATER RESOURCES 12 I Surface Wate.: 12 Groundwater Occurrence in the Upper Hunter Valley Alluvials 18 1 SOILS OF THE UPPER HUNTER VALLEY 21 AGRICULTURAL RESOURCES 22

Value of Production 22 I Production Diversity 24 Product Processing 24 Proximity to Markets 24 Discussion 25 I Summary 25

COAL RESOURCES BENEATH THE UPPER HUNTER VALLEY ALLUVIAL LAND 26 I General 26 Coal Beneath Alluvial Lands 26 Summary 29

I IMPACTS AND PROBLEMS ASSOCIATED WITH SURFACE MINING WITHIN ALLUVIAL MATERIALS 30 I ENVIRONMENTAL CONSIDERATIONS 30

Visual Impact 30 I Land Usage 31 Noise Pollution 31 Air Pollution 31 Water Pollution 31

I TECHNICAL FEASIBILITY OF MINING WITHIN ALLUVIAL AREAS 32

;. ENGINEERING FEASIBILITY 32

I INVESTIGATIONS CARRIED OUT IN THE BUCHANAN LEMINGTON AREA 34 l Soils Investigations 36 SURFACE AND GROUNDWATER INVESTIGATIONS 39

Flooding 39 I Groundwater Investigations 39 The Suitability of the Buchanan Lemington Sites as a Controlled Test Area 40 2. THE BUCHANAN LEMINGTON EAST CUT PROPOSAL 43

TABLES Table 1 Key to Water Quality Categories for Water Resources Commission Sampling 14 Table 2 Water Quality at W.R.C. Surface Gauging Stations 15 Table 3 Groundwater Quality at Coal Mining Sites in the Warkworth Area wt

FIGURES Figure 1 Hunter River at Singleton - Flood Peaks 7 Metres Exceeding Figure 2 Locations of Water Resources Commission Sampling Sites Water Quality 16 Figure 3 Skilled and Unskilled Mining Labour Requirements in the Upper Hunter 23 Figure 4 Coal Mining and Prospective Areas Upper Hunter Region 27 Figure 5 Locality of Proposed Experimental Mime Area 35 Figure 6 East Open Cut - Location of Exploration 37 Figure 7 Water Resources Commission - Location of and Sections Test Bores 41 Figure 8 East Open Cut - Plan of Proposed Method of Working 43 Figure 9 Proposed Sequence of Experimental Mining Operations 45 Figure 10 Proposed Sequence of Experimental Mining Operations 46 Figure 11 Proposed Sequence of Experimental Mining Operations 47

PLATES Plate 1 Hunter River Alluvial Flats near Jerrys Plains Plate 2 View of Alluvial Land near Archerfield Plate 3 View of Alluvial Land near Archerfield Plate 4 View over Alluvial Plain East of Coal & Allied Industries Authorisation A13 Plate 5 Buchanan Lemington Colliery Proposed Trial Open Cut Area Plate 6 Buchanan Lemington Colliery Proposed Trial Open Cut Area Plate 7 Warkworth Area Pre Mining Saline Drainage Plate 8 Strip Mining Ravensworth No. 2 Open Cut Plate 9 Progressive Rehabilitation Howlck Open Cut

Plate 10 Gauging Bayswater Creek I 3. I PLANS Plan 1 Coal Occurrences and their Relation to Groundwater Potential in the Upper Valley

Plan 2 Upper Hunter Valley Alluvial Soil. Associations Denman Scone Area

Plan 3 Soil Map of the Hunter River Flood Plain from Denman to Warkworth

I APPENDICES Appendix 1 Extracts from U.S. Department of the Interior Office of Surface Mining Reclamation and En I forcement Surface Mining, Reclamation and Enforcement Provisions

Appendix II Report on Erosion Control and Rehabilitation I Aspects of Coal Mining of Prime Alluvial Lands of the Hunter Valley - Soil Conservation Ser- vice of New South Wales

I Appendix III Water Resources Commission Hydrogeological Report No. 1979/4 .. Mining and Rehabilitation of Alluvial Lands in the Upper Hunter Valley: I Groundwater Investigation of the Alluvial Flats - Buchanan Lemington Area

Appendix IV Proposal by Buchanan Borehole Collieries Pty I Ltd for Approval to Open Trial Mine on Alluvial Lands

Appendix V Special Conditions recommended for Imposition I for an Experimental Surface Mining Operation at Buchanan Lemington Colliery I I I I I I I I I I I I I TERMS OF REFERENCE I The Committee defines its terms of reference as being to examine and report on the feasibility of surface mining of the I coal resources beneath the riverine alluvial lands of the hunter River Valley, in relation to the likely effect of such mining on

the short term and long tern rural use of the lands, the amenity

and preservation of the river channel, the quality of river water, I and any other matters of environmental concern or significance. I It is known or suspected that coal resources lie at depths suitable for surface mining, beneath the riverine alluvium in the I area generally between Singleton in the south, and Scone in the north, involving the alluvial deposits of the Elunter River and its tributary I streams Wollombi Brook and Kingdon Ponds. The Coimnittee's examina- tion therefor concentrates on this area. I I

I S 5. CONCLUSIONS AND RECOMMENDATIONS

I The Committee has examined the major technical problems and possible adverse consequences likely to be associated with the surface mining of coal beneath the riverine alluvial lands of the Hunter River I Valley in the area from about Singleton to about Scone. At the present time, thetotal quantity of coal, suitable for surface mining, beneath these lands, is not known. However, sufficient information is available for reasonable estimates of coal occurrence to I be made for three sections of the riverine alluvium, and it is estimated that in these three •sect ions there is at least 220 million tonnes of coal at depths suitable for surface mining. This would have a current value, at point of loading, in excess of $6,000 million, It is possible LI that the total amount of coal beneath all sections of the riverine alluvium could be several tines this amount. The coal resource is thus sub- [Ti stantial. There are also large quantities of coal beneath lands which are not riverine alluvial lands. Much of this coal is at depths suitable for surface mining, and surface mining has been in progress for 1 more than 30 years, Procedures have been developed, and are being im- Plemented successfully, for the rehabilitation of these lands. In some cases the land, after mining and rehabilitation, has been brought to a I higher degree of productivity than it possessed before being mined. Mining of the riverine alluvial lands, however, will pose problems of environmental and agricultural concern which have not been encountered in the surface - mining of non-alluvial lands. These will I include the following:- -

Successful rehabilitation will be of even more importance, 1 since these are generally the best agricultural lands, and are used extensively for intensive fanning.

There are useful groundwater aquifers in the alluvium being [I used to a significant extent as a source of water, principally for irrigation of crops. The aquifers would be disturbed by surface mining and it is not known whether it would be possible for them to be re-established.

The riverine alluvial lands are subject to flooding from time to time. Flooding of areas being mined or rehabilitated could create problems of erosion, sedimentation, or pollution I of the river water. &nbank'nents or spoil heaps on the river flats could affect the passage of flood waters, leading to r-ncreased depths and/or velocities of flood waters on adjoin- I ing lands. With mine workings close to a main river, there could be some possibility of the quality of the river water being affected, I even in non-flood periods; Mining close to a main river channel could endanger the sta- bility ofthe channel and trigger erosion of its bed and/or I banks. Groundwater inflows into a mining excavation in alluvium could be considerably greater than in excavations elsewhere. This H could raise problems of disposal of this water, and of stabil- ity of the excavation batters.

Surface coal mining of alluvial lands has been undertaken I overseas, notably in East Germany, West Germany and the United States of America, and mining of alluvial lands for minerals other than coal has been undertaken in Australia. However, for various reasons, much [1 of the experience available from these undertakings is not directly relevant to the surface mining of coal beneath the Hunter River Valley riverine alluvial lands. I 0

I Nevertheless, the Committee considers that present technology should be adequate to enable safeguards to be implemented and conditions imposed so that such mining could be undertaken without significant I adverse long tern effects. The Committee further considers that the only way in which proper evaluation could be commenced of the significance of the various Li problems foreseen, and of the efficacy of measures to safeguard against them, would be to conduct an experimental surface mining operation in the riverine alluvium. The operation should cover only a small area, and should be in a location where, should one or more of the safeguards Li prove to be not fully effective, the adverse effects will not have major consequence. The operations must be strictly controlled and monitored.

Until the effects of such a trial operation are sufficiently I evaluated the Committee considers that no further approvals for mining within these prime alluvial riverine lands should be granted. I The Committee further considers that all future applications must be accompanied by full evaluations of the factors involved in mining of an area.

Ll An application has been made by Buchanan Borehole Collieries Pty Ltd for approval to open a trial open-cut nine in riverine alluvium in the part of its property which the firm refers to as the "East Open Cut". The Committee has investigated this area, which covers about 30 I hectares, and considers that it would be a suitable area for .an experimental mining operation. The Committee has formulated a schedule of special conditions which. it believes should be attached to any approval issued to the firm (see Appendix V). It is estimated by the firm that mining Ii and rehabilitation of this area would be completed in about a three to four year period. 1 The Committee recommends that:- A trial experimental mining operation within prime riverine alluvial land be undertaken and I that Buchanan Borehole Collieries Ety Ltd be granted approval for surface mining of the area described in its application, in accordance with I the procedures detailed in the application. The operation would be subject to the special conditions given in Appendix V and subject to normal conditions imposed under existing I legislature.

The mining operation be carefully controlled and monitored to ensure compliance with the conditions I of the approval and to assess their effectiveness or likely effectiveness.

The Committee keep the conditions of the approval [ under review as the mining proceeds, and reconriend any variations to them which it considers necessary or desirable in the light of experience and knowledge I being gained during the mining operation. The Department of Agriculture and the Soil Conservation Service of New South Wales be responsible for the I assessment of productivity of the restored land. I 7.

I mtil the results and effects of this experimental mining operation have been adequately evaluated, no further approvals for surface coal mining of pri-me agricultural I riverine alluvial land be granted. If the total mining operation/restoration proves successful, any future application to mine in such I areas nrust be considered as a separate application and it is expected that a complete engineering and environmental assessment of the area must be I undertaken prior to any consent. The Coriunittee should continue its existence but it should be expanded to include a representative of the Planning and I Environment Conunission.

The Corrunittee should evaluate and report I on the results of the trial mining operation if approved, advise on any future applications for the mining for coal in such lands of the Hunter Valley and report on any significant I developments in the mining of such lands.

The Conunittee 's future role should be expanded to include other primc agricultural I alluvial lands underlain by coal within the State. I 1 I I I I I I I I I I I

FIRST REPORT OF THE INTER-DEPARTMENTAL COMMITTEE ON SURFACE

I COAL MINING OF ALLUVIAL LANDS OF THE HUNTER VALLEY I 1 INTRODUCTION A singular problem in the matter of mining alluvial materials is the lack of relevant overseas experience in areas similar to those of the Hunter Valley. Whilst various detailed regulations which are I of prime significance have been produced for such surface mining in the United States, no work has yet been reported upon concerning mining in alluvial water bearing sediments other than in Western and Eastern I Europe, basically in the very large brown Coal deposits of the German Democratic Republic and the Federated Republic of Germany. Also mining in other areas of the world, Russia, Montana and Wyoming occurs in widely differing climatic regimes, and experience, particularly in rehabilitation I does not apply for the Hunter area. Engineering techniques or the materials to be excavated pose no problems to existing technology. Modern equipment methods have been I developed in material handling and water control both in the civil and mining fields which are directly applicable to any such proposed project.

The Committee has accepted this premise and considers the problem I is one which is fundamentally related to environmental considerations. As such it has examined the question of whether mining is feasible from the environmental and economic viewpoints.

I Many questions arise, however some are fundamental and must be answered.

Is mining of these alluvial lands economically defensible I in terms of its effects on agricultural production?

What long and short term effects would mining have on the water quality of the Hunter River or major tributary I strecons?

Can alluvial lands be restored to their present or best I agricultural potential (productivity) after mining? This restoration would include the re-establishment of groundeater systems where such systems are of agricultural i.e. irrigation. I importance. What time period would be involved in mining and subsequent rehabilitation of these lands if such mining proved feasible? I A large number of subsidiary questions arise from these major points. Many of these are discussed in the body of this report. The Committee realises that this major problem cannot be resolved satisfactorily I without a great deal of further work and unanimously suggests that a carefully monitored experimental ortrial open cut in an area which does not pose unduly sensitive environmental problems should be permitted. This would demonstrate or otherwise under carefully controlled and I stringent conditions that such lands can be successfully mined and restored to their original value and productivity within a reasonably I short span of time. I L I DEFINITION OF ALLUVIAL LANDS

A definition of prime agricultural alluvial lands has been I accepted by the Cciinittee. Under the terms of the Mining Act 1973 and the Coal Mining Act 1973, the Director General of Agriculture has the responsibility of determining whether land is to be classed as agricul tural or not. In the United States of America, prime agricultural land [1 is classified on the basis of soil surveys - and land usage and potential (see Appendix 1 Part 716.7).

The cailnittee has accepted these bases for classification and I the advice of the Soil Conservation Service of New South Wales and the Department of Agriculture for the determination of alluvial lands in I the Upper Hunter Area. COAL MINING IN ALLUVIAL LANDS

I Relevant information on mining and rehabilitation of alluvial lands is ' -iot readily available from overseas and is of limited value. large scale operations which are described below are carried out overseas I and within Australia but in different soil and climatic conditions. Federal Republic of Germany

The West German Brown Coal Industry extracts enormous quantities I of brown coal from depths in excess of 250 metres by means of open cast techniques using bucket wheel excavators, belt conveyors and stackers, Removal of overburden to ratios of 6-7:1 involve excavated quantities in I the order of 200000 cubic metres per day. The brown coal is part of an unconsolidated water bearing sequence of clays sands and gravels of Quaternary and Tertiary Ages. I These sediments are de-watered by means of large drainage wells up to 600 metres deep. In the Rheinbraun mines some 900 wells are in permanent operation discharging approximately 130,000 cubic metres of water per hour from depths of up to 600 metres. The groundwater is of good quality I and is normally discharged into the main inland Rhine canals. Reclamation of the mining areas some of which produce up to 20 million totmes of brown coal per year is an integral part of the I mining operation. Reclamation ccxmences ininediately after mining on a progressive basis.

Land is reclaimed both to forest and to prime agricultural usage. I Loessal top soil,whjch in the area is quite thick,is placed by means of stackers into large dumps or alternatively mixed with water and poured on to reclaimed areas through pipelines (Polder method). These areas in the Rhinelarid Brown Coal District area up to 1975 included 4,300 hectares of I high quality agricultural ground and 5,300 hectares of forest. The rehabilitated forest areas are often used for recreation purposes as they I include large fish stocked lakes and are located close to major cities. In the Rhineland area some 40 villages have been totally relo- cated as well as roads, railway lines and rivers. Some of these villages I are very old, dating from medieval times. German Democratic Republic

The German Democratic Republic produces approximately 250 inil- I lion tonnes per annum of brown coal from deep open cuts in poorly con-- solidated water bearing sediments. Mining methods are very similar to I those in West Germany. The winning of these coal deposits has involved the relocation of existing urban settlements, relocation of main roads, the re-establish- ' mnt of agricultural and forestry areas and the establishment of recreation areas and water storages from the completed surface mining operations. I IN I Surface minin is generally extended into the riverine flood plains. If necessary rivers are diverted to enable winning of the S brown coal deposits. The excavations are protected by means of dewater- ing behind sheet pile screens. Dewaterin is carried out by means of wells. The Government lays down strict limiting values for water con- I tamination. Any discharge to streams of an area must be of good quality, United States of America

I Valley strip minin for coal extraction within the United States is carried out in two climatically dissimilar areas.

Mining in the eastern areas of the country has been carried out I for many years during which little environmental control was enforced until recent times. The coals of this area are hih in sulphur content and pose significant pollution problems through acidity. A large number of I acidic mine drainae studies have been carried out. The area is one of reasonably high rainfall and conditions are not really applicable to the Hunter area which the ccrrnittee is studying.

Coals of the western United States are more similar to our Hunter coals both in type and occurrence. In Utah, Wyoming and Montana large strip mines are in operation or have been proposed. Some of these are located in prime alluvial lands of river valleys. The areas have Li much lower rathfaJl than the Hunter Valley and groundwater is a dominant water source,. Much emphaSiS -is placed on theprotection of regionally significant aquifer systems.

I Little practical information is yet available from this area although research into the long term effects of mining and success of rehabilitation following mining continues. Amongst other projects the United States Bureau of Mines has initiated a large scale project involv- I ing groundwater monitoring for possible pollution, leaching of toxic overburden, monitoring erosion and sediment action. Li The United States Government however has enacted Surface Mining and Enforcement Provisions (Dec. 1977) which are particularly relevant to mining carried out in sensitive highly productive alluvial areas. These include Rules and Regulations relating to mining of prime alluvial I lands, underlain by aquifers. These regulations are included in this report as Appendix III.

I Australia

Mining of alluvial materials within riverine flood plains has [1 been carried out extensively in the past for the mining of gold, tin, gemstones and heavy minerals. Dredging for gold has been concentrated principally on the Macquarie, Shoalhaven, Turon, Cudgegong and Mongarlowe Rivers. Extensive mining for tin and gemstones has been carried out in I the New England area. Most of the alluvial gold mining took place between 1899--1958.

Mining in alluvial areas of riverine floodplains also includes I that for sands and gravels. At Penrith, N.S.W., planning for extractive industries invites total removal of alluvial material resulting in a recreational lakes system. River gravels are quarried from the beds of many streams in New South Wales, in particular, large scale extraction I is practised on the flood plains of the Murray near Albury. These extractive operations are not really applicable to the problem under consideration because total extraction is invariably carried out.

I Much of the mining of alluvial materials was carried out many years ago prior to any thought of environmental legislation. Whilst SOC 60iu urcu6iiig areas nave recovereu auu now comprise prime raruhing land, there are still areas, mainly those with very limited quantities LI of alluvial material and topsoil, which show the effects of mining. LI .Surrzrriary

In sumary, present information available from overseas and within Australia is of limited value. Studies which have cc*rinenced 1 particularly in the western United States of America are likely to provide useful results but not parameters by which local operations should be judged because of different soil types and climatic conditions. The best means of obtaining parameters by which mining in the alluvial I plain environment should be examined is by experimental, closely controlled and monitored mining studies.

I LEGISLATIVE CONTROL ON MINING IN ALLUVIAL LANDS

Any coal mining proposed to be carried out in alluvial areas I is subject to a number of legislative controls and constraints. The main controls are as follows - I Under the Environmental Planning and Assessment Act 1979 mining operations which pose significant environmental or social impacts will generally be developi-tents of a designated nature. Designated developments must in every case be advertised and exhibited prior to local I government consent. The Minister for Plannin and Environment may, if he thinks fit, call for a public inquiry and Environmental Impact Statements for any proposal. In such cases he has final approval consent. I Regulation 55 of the Eighth Schedule of the Coal Mines Regula- tion Act, 1912, as amended,. requires a person intending to counence to use land for open cut workings within a colliery holding shall, before I corrniencement, obtain the written approval of the Minister. A similar provision, can be applied to a person who was using any land for open cut workings within a colliery holding prior to 2nd June, 1978 (the date of conrnencement of the regulation) if required I in writing to do so, by the Under Secretary.

Section 38B, of the Coal Mines Regulation Act, 1912, as amended, requires:- At least thirty days before the cailnencement of any mining I operations beneath, or within 200 metres of, the vertical boundary of any tidal waters, impounded waters, stream, swamp, dam reservoir or other natural feature whether of the same or of a different kind or nature which I if disturbed by mining operations, is likely to cause damage to or danger in a mine, the owner, aent or manager shall give notice to the inspector of the district of his intention to carry out and the methods to be I adopted in carrying out such mining operations. The Minister may, whether or not a notice has been served on the inspector of the district, order in writing, given to the owner, aent or manager of any mine, direct that no mining operations shall be carried [ out in such mine beneath, or within 200 metres of, the vertical boundary of any tidal waters, impounded waters, river, stream, swamp, dam, reservoir or other natural feature referred to above, except in accordance with I such methods as may be specified by the Minister in such notice. The Water Act, the Rivers and Foreshores Improvement Act, and the Hunter Valley Flood Mitigation Act contain some provisions which could have relevance to the surface mining of riverine alluvial lands. I For the area under consideration, these Acts are administered by the Water Resources Ccmiission. The relevant provisions include: Licensing of water extraction from both surface I waters and underground waters; licensing of levee bank construction; I permissions for excavations in and adjacent to stream channels (generally, excavations are precluded within 40 metres of a river bank); approvals for works which may concentrate or divert I the flow of flood waters.

I 12. I RESOURCES OF TEE UPPER HUNTER VALLEY ALLUVIAl AREAS 1 WATER RESOURCES SURFACE WATER I At Singleton, the Hunter River has a catchrnent area of some 16 000 square kilometres, The principal tributaries of the Hunter River within this area are Woilcuibi Brook, Glennies Creek, the Coulburn River, I Dart Brook, the Pages River and Rouchel Brook. Average annual rainfalls range from about 1350 tim in the east of the catchment to less than 550 mm in the west. Annual evaporation ranges I from about 150 tim in the east to 1500 mm in the west. The average annual flow of the Hunter River is 386 000 megalitres at Muswellbrook, and about 875 000 megalitres at Singleton. This repre- I sents about 10 percent of average annual rainfall. Flows can be quite variable, however. The annual flow in any year at Singleton has ranged from more than five times the average to as little as 7 percent of average. I Glenbawn Dam, which was completed in 1958, is used to provide an assured flow in the Hunter River. It has a capacity of 361 000 mesa- litres. Glennies Creek Dam, which is now under construction on Glennies I Creek, will augment flows in the Hunter River in dry periods. The present requirements fpr surface water from the Singleton catchment amount to an annual total :of'about .157 000 megaIitres The largest requirement (about. 97 000 megalitres per annum) is for irrigation, with an estimated 16 000 hectares of.land.being irrigated.

The flood plains in the Hunter River Valley have been subject to inundation relatively frequently by overflow from the Hunter River itself I or other streams.

Inundated areas are quite extensive. Along the main river, the flood plain averages about 3 kilornetres in width between Muswellbrook and I Singleton and expands up to 5 kilornetres wide at places between Singleton and Maitland. I Near Singleton, inundation of some low parts of the flood plain com mences at a river level of about 7 metres on the &auge on. Dunnolly Bridge in Singleton. As can be seen from the attached Figure 1, this level has been exceeded on 45 occasions during the 86 years since records commenced P~ in 1892 - an average frequency of about once in two years.

The occurrence of flooding, however, has been sporadic. There was one period of 10 years without any floods, while on the other hand there I have been as many as four separate floods in one year.

A great deal of gauging and analytical information on surface water is available for the Hunter River Basin from work carried out by the Water I Resources Con-mission. The locations of the Commission's sampling stations in and around the area of interest are shown on Figure 2, and the sampling proraiime is outlined in Table 1. The ranges of measured salinities at I various sites are shown in Table 2. Waters of the Hunter River are of good quality in its upper reaches but deteriorate to marginal quality in the lower reaches of the catchment I between Singleton and Maitland. The electrical conductivjtjes of waters from Glenbawn Dam are about 380iScm-1 (230 mg total dissolved salts per litre) while those at Maitland I have been at least as high as 1100 pS cif1 (660 mg total dissolved salts per litre).

The quality of water throughout the valley is variable and dependent I upon the geological strata with which the waters come in contact. Regions containing strata such as the Narrabeen sandstones, deposited in a fresh I ------m4mm ------

HUNTER RIVER AT SINGLETON-FLOOD PEAKS EXCEEDING 7 METRES

II 1 I Is

131

I I .1 I

892 .1895 1900 1905 1910 1915 1920 Is 13 HHHHLH:,H ' H __ 7 1925 1930 1935 1940 1945 1950

AFTER WATER

RESOU RCES

CON1MISSI ON

1955 1960 1965 1970 1975 1977 11517

FIGURE 1 -

I 14. TABLE 1 1 K EY TO WA TER Q UAL I TY C A TF GORIE S FOR

Class 1 Comprehensive sampling 2 times/yr

Intermediate 11 i i 2 times/yr Basic about 4 times/yr

I Class 2 Intermediate 2 times/yr Basic I about 6 times/yr Class 3 Basic sampling I about 8 times/yr

I 9prehensjye

Phosphates Ammonia Detergents I Nitrates Heavy Metals Algae Bacteria

plus all Intermediate I and Basic tests. I Intermediate Cations Anions Iron Fluoride I Boron plus all Basic tests.

I Basic

Temperature pH Turbidity I Colour Conductivity I Ii I 11 I

' I I I 15.

no I TABLE 2

I Water Quality at W.R.C. Surface Gauging Stations 0

1 Electrjcal* Total Dis. Conductivity solved SkiT (pS/cm at 2) t97T Hunter River 1 (Rouchel Confluence) 284-720 180-460

Hunter River (Muswellbrook) I 292-1038 190-660 Hunter River (Denman) 265-820 170-520 Hunter River (Liddell) I 3460174/ 230-11.00 Hunter River (Singleton) 211-1180 130-750 Dart Brook I . 260-2500 170-1600 Goulburn River 483-1420 310-910 Wollar Creek I 385-3086 250-2000 Baeramj Creek 223-1100 140-700 Martjndale Creek I 180-1050 110-670 Doyles Creek 112-1626 70-1000 Saddlers Creek I 1389-8900 890-5700 Saltwater Creek 3085-10725 2000-6900

I Bayswater Creek 1100-6100 700-3900 Bowmans Creek 222-2400 1401500 1 Glennjes Creek 145-1300 90-830 Wollombj Brook I 200-2960 130-1900 O Data supplied by N.S.W. Water Resources Commission - Location of Stations shown on Figure 2. I * 0 Electrical Conductivity (in pS/cm at 25 C) x 0.64 1 Total Dissolved Salts (in rng/L) approx. I I I I — — — — — — — — — an — — — — — — — — — —

31.1,01k I 17. water envirorunent, yield waters of very good quality. cccne Waters which have in contact with basaltic rocks are generally of marginal quality, while very I poor to bad quality waters are obtained from streams draining Permian aged sediments deposited in marine environments. ; The connate salts contained in the Permian aged marine sediments are predominantly sodium chloride, I and monitoring of this salt can be used to assess the impact of these sediments on water quality. - ' The Permian marine sediments underlie much of the recent alluvium and are exposed in two areas, one near Muswellbrook and the other between Singleton and Maitland.

The aquifers in the marine sediments contain very saline water. I The rate of accession to the main river channel depends upon the river's height. When large volumes of surface discharge occur in- the river, fresh water recharge of these aquifers forces the saline waters away from the I river, conversely low river levels allow the saline waters to migrate towards the river. The waters in the river channel are of lower salinity than waters in the surrounding alluvium, depending on the surface dilution I flows available. High salinity waters occur along the lower reaches of the Coulburn River and Wollombi Brook, reachin nearly 3000 ditions. jiS an under low flow con- The waters in the alluvium of the lower catchments of these I are associated with Permian marine sediments. rivers

Surface saJtjo has occurred on alluvial flats in the lower Wollombi catchment possibly as a result of land clearing. I patches has been reported. to :be increaing The area of salt.

Several creeks in other parts of the Valley have incised the Permian marine I sediments and yield water of such high -salinity that they are unsuitable for all agricultural uses. . The water salinity in the Hunter River at any time is largely de-' I pendent upon the proportion of the discharge contributed from Glenbawn Darn, The higher the proportion of discharge from Glenbawn Dam, the lower is : the salinity.

1 The variability of water quality in the lower reaches of the Hunter River is a cause for concern with respect to irrigation of salt sensitive crops. Since the salinity of water in the vicinity of Maitland can reach levels deleterious to certain crops, irrigation practices need to be care- I fully considered, and management of water resources with respect to salinity is a matter of priority for investigation,

. A review of water quality in the Hunter River Valley is presently I in preparation by the Water Resources Ccmnission. I I I I 1 I I IN GROUNDWATER OCCURRENCE IN THE UPPER HUNTER VALLEY ALLUVIALS I The most important sources of groundwater within the catchment, in terms of both water quality and yield, are Unconsolidated formations of alluvial origin in the major I river and tributary valleys of the area. The alluvium consists of clays, silts, sands and gravels deposited in the floors of valleys after being trans- [I ported there by water. The weathering and erosion of rocks within the catchment has provided the source material, and thus the nature' of the rocks 'determines the nature of the LI alluvium. Examples of this are:-' Coarse basaltic gravels in valleys draining the Liverpool Range e.g. the Krui River, Merriwa and I Halls Creeks, Munmurra and Dart Brooks. The sands in the valleys draining the southern and western sandstone plateau e.g. the Goulburn River, I Baerainj and Martindale Creeks, Wollombi Brook.

The varied rock types in the gravels draining the older Carbonjferous rocks east of the Hunter Thrust, 1 e.g. the Pages and Hunter Rivers.

The groundwater resources of part of the - alluvium I of the Upper Hunter Valley (between Glenbawn Dam and the confluence of the Goulburn River) have been investigated in some detail by The Water Resources Commission. This section of the Hunter Valley is one of the most intensively developed areas I for irrigation by groundwater within New South Wales. However, the potential for irrigation supply from groundwater sources varies considerably within the area, from 1 considerations of both quality and yield. Groundwater in various localities shows characteristics which reflect the nature of the underlying and adjoining rock series which flank the river and tributary catchment areas. Quality of ground- I water is also reflected by the flank topography of the alluvial valleys. Williamson (1958) reports "It is usual for the groundwater to be more saline with distance from the river but in some cases, good quality water occurs near the edge of the I flats, usually associated with high permeabilities of the alluvium or the flank topography being too steep to provide much local catchment for surface or subsurface drainage. Con- I versely low permeability in marginal zones or gently sloping flanks are specially associated with unfavourable rock series and tend to give rise to poor quality groundwaters in those I areas'. Unfavourable rock "series" in the catchment area include the lower or Greta Coal Measures and the Upper Marine Group (Daiwood Group) which flank areas of the valley in the I Muswellbrook, Jerry's Plains and Singleton areas, and the Singleton Coal Measures which lie beneath and flank much of the riverine alluvium areas between the Liverpool Range and Li Singleton. These rock "series" generally contain groundwaters of high salinity, and run off from them and associated tribu- [1 tary flow, is generally of poor quality except in times of exceptional rainfall and streamfl.ow. The range of salinities of some of these streams is given in Table 2, and the salinities of groundwaters from various locations within the Singleton I Coal Measures is shown in Table 3. I ------

Groundwater Sample Station pH Total E.C. Chloride Sulphate Nitrate Calcium Magnesium Iron Potassium Sodium Alkalinity (ms) (CaCO3) (ion content as mg/i) T18 7.1 15,000 4.080 470 - 1.3 - - 2,300 600 Groundwater seepage. J _+ (WarkwortMin:ng) ___ 4:270 410 4 113 385 01 55 2:650 T 24 3uchanan Lemington) 8.4 11,000 2,770 550 9 j Groundwater seepage from 57 I 380 0 05 29 o. 2 mine box cut 1,530 760 carbonaceous shale over- I I lYing Mt Arthur seam. T 25 uchanan Lemington) 8.0 11,000 3,760 430 6 29 Underground mine water o. 2 mine box cut 410 0.05 34 2,300 1,150 I and groundwater seepage from sump in box cut. 1 26 8.6 13,000 3,850 560 Pump out from upper (R.W. Miller) 1 I______76 400 0.25 i 512oss f settlement dam. Source sump in box cut. T 21 7.9 (R.W. Miller) 2400 630 96 1 360 Settlement dam. Source , I 377 1 I pump out from box cut.

T23 8.1 18,000 4,430 430 8.1 12,000 4,270 410 ..I 2,900 1,260 Settlement dam. Varkworth Mining) 1 100 375 I 0.15 55 8.0 14,000 4,007 375 2,650 1,250 Source pump out 7.8 12,500 2,690 4,050 365 2 50 320 from box cut. 1,280 __ - T 15 7.5 15,000 3,810 430 2,550 1,450 Groundwater Spring se ep- 1 ing into creek.

TABLE 3 Groundwater Quality at Coal Mining Sites in the Warkworth Area

Li 20. Within the area of alluvium between Glenbawn Dam and the Hunter/Goulburn Rivers confluence test boring has shown the alluvium to be relatively thin, usually 12 - 15 m but even so, of the order of I of water bearing gravel/sand.wells rarely penetrate the full sequence The sequence of strata usually consists of 4 - 6 m of silts and clays, Overlying water bearing I silts.gravels, which include varying proportions of sands, clays and In general, wells 7 - 12 m deep yield 10 - 40 L/s over most of this alluvial area, which includes the important 1 tributaries of Pages River, Kirigdon Ponds and Dart Brook, Yields in the Muswellbrook/Denman section of the valley tend I to be lower. Water quality within this area varies Considerably. Williamson reported salinity increases in flank zones with unfavourable rock types, which are probably related to dry and wet season periodicity and the leaching of accumulated salts from the Soils in very wet years. However, in the main part of the valley the salinity is generally satisfactory and does not vary markedly, as indicated by the 1946 to 1953 data I in Williamson?s report and subsequent measurements by the Water Resources Commission.

The Commission has indicated that whilst further de- I velopment of groundwater for irrigation and town water supplies is quite possible in the Upper Hunter area, the situation is not without a nurnber of problems. Williamson defined large I areas with relatively poor groundwater potential, i.e. those Containing only occasional wells Yielding supplies sufficient for irrigation purposes There are also problems of water level fluctuation with seasonal Conditions and the Possibility of increasing salinity by inducing movement of the poor quality I water from the fringe areas.

From the Hunter_Goulburn Rivers confluence downstream I to beyond Singleton, the alluvial flats generally occur as alternating meanders, with Permjan marine and coal_measure sediments forming the valley slopes. These rocks contain saline material or shed water of higher salinity by leaching, I and this influences the quality of the water under the flats for a considerable distance from the flanks of the valley. In some cases wells have to be located half a kilometre or more from the slopes in order to obtain water of irrigation quality. I Wells at selected sites in these areas have fair prospects of obtaining yields of 6 - 20 L/s.

Where the side slopes contain very 1 groundwat saline water, the in the alluvium nearby tends to be too saline for irrigation e.g. south_east of Jerrys Plains.

I the flats. There are a few bores in the elevated country off These generally yield stock supplies of brackish to saline water, which in most cases is suitable for the 1 watering of large stock. Well usage in this area is relatively limited. There are only some 64 licensed irrigation wells between the Hunter- Goulburn Rivers confluence and Maitland Other Unlicensed I wells may exist, but most of the water used for irrigation in this area is pumped directly from the Hunter River.

alluvi The catchment of Wollombi Brook and its associated I al areas also forms a significant part of the valley. This extends into rocks of Permjan and Triassic age, and both surface and groundwater are generally more saline than in the main Hunter Valley. The alluvi um is Predominantly sandy, and j yields up to 15 L/s are obtained from batteries of spear points. Where suitable gravels occur, wells may yield up to 12 L/s. I I 21. Plan 1 shows the relationship of coal occurrence and groundwater potential. It is important to note that some areas of high coal Potential are associated with areas of poor groundwater potential I For instance, the area between Mangoola and Muswellbrook has poor groundwater potential, but is likely to contain in excess of 100 million tonnes of steaming quality I coal which could be extracted by surface methods. I SOILS OF THE UPPER HUNTER VALLEY Soils maps are available for the area of the Hunter Valley flood plain between Warkworth and Scone. These cover all areas of floodplain underlain by rocks having coal bearing potential I The soil groups are depicted on the attached Plans 2 and 3 which are summaries of original soils mapping carried out by the CSIRO (Brewer & Butler 1953) and the Soil Conserva- r tion Service of New South Wales (Hannan 1978) Both maps identify five main the soil associations within river flood plain area and apart from several small of residual material inhiers (in the area between Denman I all the soils and Warkworth) are of alluvial origin.

Brewer and Butler proposed that various soil of the flood plain series have been formed on parent I down during materials laid successive periods of deposition following of river erbsjoii of J)eriods part of the flood plain. The primarily in soils differ grain size rather than in The mineral COflstitutjon. alluvial soils above Denman I show evidence of halomorphism or solonjsitioii i.e. the redistribution soil of salts through the profile to produce an alkaline (sodic or non saline) which is related to soil I the age of the soil groups. This relationship appears true for that part of the Upper Hunter Valley between Denman and Singleton. Here the intricate pattern of soil associations reflects changes I river flow regime during in their period of deposition. soils are the result These of deposjtionai cycles during times and it is recent probable that older buried water bearing horizons and the sands and gravels also I complexity. may exhibit stratigraphic

Prime agricultural lands in Europe affected by surface mining appear to consist of I loessal or glacial till soils overlying the extensive coal deposits. The and generally soils are deep well drained, not being flood plain. confined to a river The upper fertile rated horizons can be readily from the underlying sepa - I material. Because of the nature of the overburden soft material, it can be into discrete units. readily separated This facilitates and storage and simplifies the replacement of overburden few topographic components. There are I constraints which would serve to inhibit areal extent of operations the

By comparison the enviroj1mit flood plain of the Hunter River ' appears to be somewhat unusual compared to parts of the world where other surface mining has taken .prime agricultural place within lands. While it is not of the United as dry as the areas States of America mentioned as climatically above, neither is it I favourable for Europe revegetation as parts of where similar mining central prime ventures are in progress. soils of the Hunter The narrow Valley are contained within limits imposed rather by hilly land on both I watercours e in the sides and the valley centre. The siderably more alluvial soils are con- variable in age and than is both aerially and with the case with glacial depth, and loessal soils. I L 22.

The alluvial soils of the section of the valley studied are roughly equal in terms of fertility, erodibility I and potential for agricultural production. All the soils are highly productive and all are susceptible to rapid and severe erosion to considerable depth once the protective .1 mantle of vegetation is removed. I AGRICULTURAL RESOURCES Since the earliest days of settlement agriculture has been an essential element of the economic and social struc- I ture of the Hunter Valley. Agriculture is the largest occupier and user of land in the Valley; it is the most decentralized industry, and a significant generator of employment opportun- ities. In eight of the fourteen Local Government Areas (1978), I which cover 90% of the Valley area, agriculture is the major occupation of the work force.

Employment of-people in farming pursuits has declined I over time, but there are still some 7, 500 people directly en- gaged in agriculture in the Hunter Valley. For the area under consideration in this report the figure is just over 3,000 I people in 1977. In those sectors of the Hunter Valley which are subject to possible future coal mining operations, agriculture is I still the largest employer of labour. The position undoubtedly will change with the development of large collieries and power stations and ancilliary manufacturing and service industries. Agriculture however will still play an important part in employ- I sent, Hunt 1978 has derived figures for projected labour requirement in the mining industry for the Singleton, Muswellbrook and Scone local government areas which illustrate these inter-- I relationships. This is illustrated in Figure 3. Agriculture in the Hunter Valley has a number of features which set it apart from most other farming areas. I These include: - High total value of production. I - Diversity of enterprises with the Valley. - Productive areas situated near centres of popu.-, I lation and markets. - Processing of much of the locally grown produce with the Valley. I - Heavy dependence on fertile, alluvial soils for intensive farming activities.

- Particular reliance on regular supply of stream I water of satisfactory quality to maintain irrigated farm production. I Value of Production The Hunter Valley is one of the top producing agricultural areas in N.S.W. In 1977-78 total agricultural production I exceeded $121m (farm gate values). The leading agricultural enterprises are dairying, beef cattle and poultry. Their relative importance varies I according to prices and seasonal conditions. The significance I I SKLL.ED .AN:D.UNSKJJ!E:D MINING LABOUR EUUREMENTS IN THE UPPER HUNTER

I SOURCE; HLnt (1978) The. Impact of. Coal Mining on the Upper Hunter" I I

--:----- I APr'ROX. T0VL: .WORKFORCE flNG1.E.TON . MUSWEI I)3ROOK r'- DENMAN - 13 SCONL. I I I LI

I UI 0. - C) 0 TOlAL C0A1;.'1HNINc,,. L I - EMPLOYMEN. I .8- s.- lu .. KII.LED I 'S Mft1ING 1 EMPLOYMENT'/ Lt. VE / éWPROX. AGRICULTURAL . .. . • .. I lu .. / 6 - EMPLOVMENT'. 1977

SINGL.ETON - MUSWELLBROO . / I / 5 fREA-- •::-,', I

I I

UNSKILLED I 2- . MINING EMPLOYMENT I

I 1915 1980 1985 1990 .1995 2000 I Y E A R I 2L,.

I of the local Dairy industry may be gauged from the fact that the Valley provides approximately half of Sydney's fresh milk supply. This proportion has increased as some dairy enterprises have transferred their operations from the Cumberland I area to the Hunter Valley. Virtually all dairy farming is 'located on alluvial land and adjoining lower slopes.

In addition to actual farm production, some elements of the agricultural industries in the Valley provide the basis for other activities. Most prominent •amongst those is the I tourist industry associated with the vineyards. Production Diversity

A feature of Hunter Valley agriculture is the diversity of enterprises.

While dairying, beef cattle and poultry are the major I industries, vegetable growing, lucerne hay production and cereal cropping amongst others, are of particular significance. Alluvial soils and irrigation are of special importance for I vegetable and - hay production. Prime examples of the minor but still important industries are carrots and lucerne hay. Almost the entire carrot growing industry of N.S.W. is located on river alluvials I in the Singleton district, while lucerne hay production is estimated tc exc:eed $3 million annually.

Product Processing

The significance of agricultural production in the Hunter Valley is enhanced by the Local processing of much of I the farm produce. Apart from poultry abattoirs, three other works slaughter cattle, sheep and pigs. Milk and dairy products are I processed at five factories. Twenty eight wineries produce wine from locally grown grapes.

This aspect of Hunter agriculture enphasises the I dependence of a large number of non-farm jobs on farm production. This position will undoubtedly change as the development of mining increases in the 1980s. (See Figure 3). It seems certain that agriculture will suffer in the competition I for labour because of the much higher wages available in the mining industry. Some drop in production of these areas could occur.

I Proximity to Markets

The need for farming areas to be located near to large popu lation centres was of crucial importance in earlier I days. The energy supply problem and increasing costs of transport will place renewed emphasis on the importance of Hunter Valley farniands because of their proximity to people I and markets. At present, Hunter agriculture exhibits the classi- cal von Thunen pattern of more intensive agriculture close to I population centres and more extensive enterprises in remoter localities. This pattern is modified to some extent by the importance of soil quality and water availability for I irrigation. Consequently the more intensive farming enterprises are to be found mainly in the lower Hunter but also on areas adjoining towns in the upper Hunter and extending along the I fertile soils of the river valley and tributaries. I I 25. Alluvial soils support virtually all of the Valley's dairying industry, the Vegetable farms, the major lucerne growing areas and cereal crop production.

I D-t8Cu.9jQfl

Agriculture is the largest occupier and user of land Li in the Hunter Valley and is most vunerable in the face of competition from land users. Agricultural lands have been aliena- ted recently by such developments as parkland residential sub- I divisions, water storage, coal mining and electricity generation. Surface coal mining operations in the valley to date have been located on areas of low agricultural productivity. Li Some mined lands have been satisfactorily rehabilitated, to better premining usage than before, under procedures laid down and supervised by the Department of Mineral Resources and Develop- I ment and the Soil Conservation Service of New South Wales. From the point of view of agriculture the extraction of coal from highly productive alluvial areas is a far more important problem. This land is capable of Supporting two I dairy cows per hectare or producing equivalent crops compared with one beef animal per 3 hectares. The productivity of the land each year is guaranteed by the availability of water for I irrigation. The Department of Agriculture has studied two alluvial areas in the Singleton Muswel1book area known to be underlain by coal which could be mined by surface methods. I These areas and their immediate Surroundings contain some 42 farms, including stud horse breeding, which when assessed on the basis of their productivity yield an annual production of dairy products, beef I and cereal crop of the order of $2.3 million. * The most important item Considered by the Department is the potential loss of milk production and its effect on local milk factory management in terms of Profitability. In the areas underlain by signifi- i:ii cant quantities of coal on Plan 1 between Singleton and Muswell- brook, some 17 farms produced 13% of the local dairy's milk production up to April 1979. Loss of beef cattle turn-off or lucerne and cereal crops would not have the immediate effect I that loss of milk production would have, but pose serious problems in the longer term.

Other alluvial areas of the valley underlain by coal I would pose similar agricultural problems - those in the Scone area are considered more important than those near SingIeoz - because of their higher productivity. 1 Summary

Loss of alluvial land to mining poses signific ant I land.short term problems in removing from usage highly productive In terms of monetary value, agriculturj production will not compare with revenue generated by coal mining but the long term importance of intensive agricultura' usage of I alluvial lands is stressed.

The Committee believes that it must be successfully demonstrated that alluvial lands can be restored to their pre- I mining potential within relatively short periods of time so that serious effects on local agriculturJ viability and pro- I fitability would not occur. * Estimated \'alues of in situ coal within these areas are in I excess of $500,000,000 of average present day values. I I 26. COAL RESOURCES

I BENEATH THE UPPER HUNTER VALLEY ALLUVIAL LAND General

I In the Upper Hunter Valley two ages of coal bearing sediments occur. They ar.e the Early Permian Greta Coal Measures, which are separated by a sequence of marine sedimentary rocks called "the Maitland Group", from the later - Permian Coal Bearing I sequence, the Singleton Super Group.

The Greta Coal Measures crop out on the valley flanks north and e astofMuswellbrook and do not underlie significant I areas of alluvialland at depths which might be worked by surface means.

I The Singleton Super Group, in turn, contains two dis- tinct coal bearing sequences, the lower Wittingham Coal Measures and the stratigrapftically higher Wollombi Coal Measures. The Wollonibi Coal Measures flank and underlie the southern and I wesiern fringes of the main Hunter Valley and the tributari es of the Hunter Rjvriear Den-man. No economic sections of this coal sequence have yet been delineated but areas north west of Denman may prove promising if results of recent drilling- in I the area is confirmed by further investigation.

The Nittiiighaiit:Co-al Measures constitute the major - future sourc;e of coal. in New South Wales both for domestic I consumption and export. 'The sequence crops out over the central valley floor and its northern flanks and contains over 40 coal horizons. At least a third of these could be economically worked by surface and underground mining methods. It is the I coals of the Wittinghain Coal Measures which underlie prime agri- cuJ lural land on the riverine flats in certain sections of the valley. The relation of coal •bearing lands and various, exploration I and mining titles held by government and private industry in the valley and the alluvial lands are shown in - Figure 4.

I - Coal beneath Alluvial Lands

Plan 1 shows the known distribution of shallow coal bearing sediments having high extraction potential the from beneath I alluvia) fiat and terrace deposits.

Sufficient investigation has not yet been carried out throughout the valley to clearly define coal occurrence beneath the airuvial lands I of the valley. This is basically due to companies reluctance to -expend funds on land where - great difficulties are posed in obtaining access and no guarantee there is . to firm title to areas. to It is however possible I make the following comment concerning known coal occurrences.

1. The section of Wollombj Brook from Payne's Crossing to Warkworth does not appear to contain large reserves I of coal which could be mined by surface methods. Wambo Colliery holding occurs in this area and the company has indicated there is little potential for surface mining of I these areas of alluvial lands. Similar comment can be made for the western sections of Authorisation No. 32 held by Broken Ihill Co. Ltd and Proprieta r y Authorisation No. 66 by R. h Pty. Miller Co. Ltd. There could be I some potential for limited shallow coal in the area between these two Authorisa tions but this is unlikely. It is expected that this area will be assessed I fully within two years.

I I 27. I I - - I COAL MINING AND PROSPECTING AREAS UPPER HUNTER REGION

------I I

I L(fiy 4xa..o. a.Qcn I;

U I '_"•7• ';:. H — aa ... •a. - I I

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I r. • T I — --- LJ I r I

I FIGURE i I I ME

The alluvial flats within the Buchanan Lemington Colliery Holding between the junction of Wollombi I Brook and the Hunter River contain an estimated 17 million tonnes of in situ coking coal of the Mt Arthur/Piercefjejd Seam Complex. This occurrence is restricted to the river flat areas south of the I junction both to east and west of the Hunter River. Coal occurs beneath both the Hunter' River and I W011onibj Brook alluvials. The area of river alluvjals south of Authorjsatjon No. 41 held by Consolidated Goldfields of Australia near the junctions of Glennies Creek and Bowman's I Creek with the Hunter River is thought to be underlain by significant quantities of shallow coal. Not enough data is presently available to assess this area. It is expected that this may become available within a I period of 1-2 years.

Good quality alluvial lands are developed along Glennies Creek. These lands overlie coal measures I sediments of the lower part of the Wittingham Coal Measures with limited open cut potential. The villages of Camberwell and Glennies Creek are located in this area and pose severe environmental problems I for potential surface mining development.

Three separate authorities for ca1 exploration occur I in this area. Authorities No. 44 Maitland Main Pty Ltd and No. 89 Bloomfjeld Collieries Pty Ltd do not Contain significant alluvial lands underlain by shal. low coal. Authority A81 embraces the Camberwell I village area and is held by Eric Newham Pty Ltd. The company has expressed some doubt of the viability of coal extraction in this area particularly near the Village of Camberwell. Only small quantities of coal I are liable to be sterjlised should mining be precluded in this area.

Authorities A13 and A28 previously held by Coal and I Allied Industries Ltd and the Newcastle Walisend Coal Company respectively occupy the central floor of the Hunter Valley between Glennies Creek and Jerry's I Plains. The tract of alluvial land immediately south of Hunter Valley No. 1 Colliery contains at least 56 million tonnes of shallow coal which can be extracted by surface mining. Nearby Authority No. 28 is disrupted by faulting and extensive cinderijg of coal caused by [1 igneous intrusion The Authority, apart from the river alluvial section, has reported Potential for only limited underground mining. Some 42 million tonnes I of Predominantly steaming coal however are present, at surface mining depths, beneath the alluvium covered central section of the property. I The Jerrys Plains area has been prospected intermit tently in the past without a great deal of success. ThisBayswat area however has been recently granted to the Colliery group and it is expected that I knowledge of the area will improve substantially over the next two years. The area is environmentally com- plicated by the township of Jerrys Plains Which has been tentatively designated as a possible growth area. I From Jerrys Plains to Aicheringa further work needs to be carried out to clarify coal occurrence. The area is of doubtfil value for mining of surface coal LI within the riverine flats. I

1 29. 7. At Alcheringa the Singleton Super Group downthrown sequence is sharply to the west by I Fault the Mt Ogii0 which extends northward from Aicheringa Castle Rocks. The through area to the west is both) Wolloinbi underlain by and h'ittingham Coal been Measures and it investigated by has I Carpentaria Exploration who have held Pty Ltd Exploration Permit Tender for several Area No. 2 years. A further immediately Exploration Tender west of this, Area generally south ship of Denman of the town- I is presently being Considered This will improve for issue. knowledge of the area shallow economic but as yet no coals have been is encountered but some Potential north there of Denman. The I alluvial areas have riverine little Potential ments. for coal develop

8. The area of biittingham Coal I the outcrop Measures sub crop of the Edinglassje between Seam 5 km west Muswellbrook and the of Mount Ogilvie Fault borough) has high (near Rox- Potential for possible ing operations surface min- I within the alluvium This area covered areas. lies within Authority No. 102 held Department of Mineral by the Resources and Authority No. Development and 15 held by the of New Electricity Commissj0 I South Wales (Mt ity Arthur North) and Commission in The Electric association with (Mi: Arthuy Suth) private' enterprise An area, of 18 fiats is km 2 of alluvial estjThated to contain at least 75-100 I tonnes of Predominantly million steaming of alluvium type coal at depths cover ranging from 12-17m approximately. A small area immediately south west east of Dorset of Kayuga due and Coal Creek Roads may Contain quantiti5 of shallow good coal. The area the limits of lies betweenbetwee n the Bayswater Seam and Edinglassj0 subcrop. More data I will become available this area when the on Department of Mineral investigation is Resources Completed during 1980. Potential shallow coal also the Possibly occurs strip of alluvial beneath lands flanking Kingdon and Parsons Gully Ponds Creek, a little Road to north of Dartbrook approximately 2 km south of Parkville. I information is available Little on coal occurrence area and further in this investigation is required. Ill. Though not fully prospected it appears that butary valleys of the tri-- the Goulburn River Potential have little for any large scale coal. development of Open cut I Summary

The main areas of alluvial lands which are presently I known to be underlain by significant coal reserves are - (a) Between Parkvjlle and the Dartbrook Road. (b) West I of Muswellbrook to Roxborough (c) South of Liddeli between Bayswater Creek and I MOntrose. Much more investigation remains to be carried out to delineate coal resources in most of these areas as little in- tensjve investigation has taken place. coal which However quantities of I lie beneath these areas is of great value. In excess of 220 million tonnes of Predominantly steaming coal (represent- I ing values in excess of $a,000 million) have future extractioi 30.

potential over limited areas of the valley alluvial lands. These areas are shown on Plan 1 which illustrates the relationship between coal and groundwater occurrence.

IMPACTS AND PROBLEMS ASSOCIATED WITH SURFACE MINING

WITHIN ALLUVIAL MATERIALS

The Hujiter River alluvial lands in the area considered are essentially confined to a narrow belt adjacent to the main I river bed. The alluvium has an average width of approximately 2 km and has an average thickness of 12-15 m. - The maximum I thickness encountered in drilling is approximately 19 m near

The alluvial sequence typically comprises a highly productive topsoil, zone of 0.5 a overlying 12 m of silts and clays. This sequence often increases in clay content with depth. These fine grained sediments are underlain by water bearing gravels which contain varying proportions of sands, silts and clays which determine the effectiveness and properties of the aquifers.

In areas underlain by coal bearing sediments the aqu_ fer materjaj lies immediately above' slightly weathered bedrock Consisting of inerbedded siltstones sandstones, claystone s and coal seams, Away from the riverine recharge areas these aquifers Li contac;. with coal measures. sediments are often too saline for use iii irrigation. Near to the river generally they are established or Potential sources of irrigation water.

The major problems associated with mining developmeiit on the riverine alluvial plains are environnenta1 As well as those normal environ2nental problems associated with surface miii_ ing, special problems arise in these sensitive areas.

ENVIRONMENTAL CONSIDERATIONS

Normal environmental problems associated with surface mining in sensitive areas will Occur.

Visual Impact

The alluvial flat areas are some of the most scenically attractive areas of the Hunter Valley. Any mining operation must have significant but assuredly temporary visual impact. The low lying nature of the flood plain alluvial areas tends to emphasise the impact. This is in part tempered by the general inaccessibility of the Central section of the flood plain in much of the area. areas underlain by large quantities of coal ParticuSom e the river flats east of Jerrys Plains, and those southla rly west of Muswejlbrook in the Mt Arthur area are located near major roads. sidered suitable forThe mining riverine flood plains are not con- infrastructure or Stockpili and all development on the plains including levee banks ng would be of a transient nature

The necessity of Stockpiling from the riverine flood plain ofwould overhul.den materials away impact partly alleviate visual Plant movemej)t would impact be the major contributor to However the cyclic short term nature of the oper- a t i o n (involving progressive take place minimise5 the area rehabilitation) of surface which would excavated at any time. which would he Restored land would blend normally with Crop land at any time. typical alluvial agricultural Platesland. 1 to 4 show views of 31

I 2. Land Usage

Alluvial lands of the Hunter floodplain are tile most pr I ductive in the Hunter Valley. Much of the land is regular- ly cropped or cultivated, particularly near market townships, or alternatively, is capable of producing high yields of crops or good milk yields, The land generally has a high I usage, however there are exceptions as some properties have not been continuously worked to their full potential.

A mining operation in alluvial lands would disrupt tradit- I ional usage by taking the lands, at least temporarily, out of agricultural production. A viable mining unit which on the flood plain would probably not exceed 30 Ha, would be I taken out of the production cycle for probably 2-3 years at a minimum, probably 3-4 years is more likely as nearby mining operations would still be taking place.

I At any one time not a great deal of this land would be tied up by mining usage for a variety of reasons which include the necessity for seeking approval for individual operations, necessary, progressive and timely restoration of lands and I restriction on size of operations in a flood plain area.

The re-establishment of the prime agricultural potential of the land would be a necessary prerequisite of any opera- I tion in this area,: - I Noise Pollution This would generally tend to be less than for a surface mining operation elsewhere. The unconsolidated nature of the alluvium would preclude extensive blasting and this I may be virtually absent if the underlying consolidated Permian sediments could be "ripped 0 by' the excavating machinery, The enclosed nature of the excavation also would tend to detrease noise. Most noise could be expected I from trucking and placing operations for overburden stockpiling and rehabilitation. The flood plain areas are ob- viously not densely settled however properties generally are smaller and visual attraction of the riverjne lands I has created a natural tendency for homesteads and properties to take advantage of views overlooking these areas. Noise may not be a very significant problem if subject to effective controls.

Air Pollution n Dust problems would be far less for this type of operation than for a dragline/strip operation. Excavation by truck- shovel-scraper operations in this type of material would create less dust problems than a dragline operation. The I water bearing nature and soil moisture content of the alluvial overburden also indicates significantly less dust problems than in the hard rock overburden situation. Meas- ures would have to be adopted to control dust pollution by I wind erosion from stockpiles located away from the flood plain, truck movements or soil replacement on the flood plain.

I Water Pollution

This potentially is the most serious environmental hazard of mining operations on a riverine flood plain. River I Pollution is possible from a number of aspects of the operation by discharge, unavoidably or otherwise, of saline or sediment hearing waters to the mainstream. This could take I place through - I I 32, Uncontrolled run off from stockpile areas, roads or materials containing potential salt pollutants. I Salinity problems are essentially restricted to the Permian coal measures and associated saline aquifers. Care would have to be taken that such run off was contained in areas away from the riverine flats and I could not unduly contaminate reconstituted aquifers although this is a natural process which takes place throughout the valley. (See point (d)).

I Run off from coal stockpiles. Coal stockpiles should be located well away from the riverine environment to I preclude saline and acidic discharge from these areas. Flood erosion by means primarily of suspended solids. In the worst instance removal of levee material and subsequent flooding and scouring of earthworks and the I excavation could occur and eroded material deposited downstream. Care would have to be taken against any change in restored ground levels leading to change in I local flood regimes and paths. Contamination of aquifers. Saline run off from mine areas to the riverine flats could cause pollution of aquifers (existing or reconstituted). Aquifer cut I off against Permian Sediments above w'ater table level would have to-be ensured prior to aquifer re-establishment. No disposal of contaminated water should occur on the flood plain. This would include road watering I with saline material. I TECHNICAL FEASIBILITY OF MINING WITHIN ALLUVIAL AREAS If mining were to take place in the riverine alluvia] area the Committee considers that four main basic premises must I be satisfied. Firatly - the integrity of the river (its bank system and flood regime) must be preserved. Secondly - I no polluted water either from saline aquifers within the alluvium or from any excavation can be discharged to the river system unless approvals I are granted under the Clean Waters Act. Thirdly - any aquifer system capable of supplying irrigation quality water at an economic and significant rate 1 to prime agricultural lands should be replaced after excavation.

Fourthly - lands must be restored to their original potential I productivity within a finite and reasonable period after mining. I ENGINEERING FEASIBILITY Any mining proposal in the alluvial flood plain area must be thoroughly investigated, researched and designed with I the aim of restoriig the disturbed land. Excavation handling and replacement of alluvial materials is expected to pose no difficulties if appropriate I modern equipment is used under effective supervision. An essential prerequisite to any mining proposal is F' a thorough detailed investigation programme. I 1 '3. It would be essential that the engineering and hydrogeological parameters of the alluvial material be thoroughly determined. I Detailed hydrogcologicai soil and geotechnica studies would need to be carried out to determine soil profiles, the stratigrapliy and engineering properties of the unconsolida_ ted, alluvia] overburden as well as pre-existing groundwater I Conditions in the area proposed for mining.

On the basis of these studies it would be possible to estimate groundwater inflow from aquifer systems encountered I and then onJy to design measures- to prevent cont aminntion of and make appropriate use of such water. Better angles and do- I watering systems would- be included in such design. Any excavation would need to be protected against possible river inflow. At both times of normal flow or flooding, a barrier sufficiently wide to ensure safety and integrity of I the river bank is required. This committee suggests that the 40 m barrier presently in force through the Water Resources Commission regulations and the Mining Act provides a good safeguard. All excavations need to be protected by levee banks from I possible fJoodig. The banks must meet the criteria established by the Water Resources Commission for their construction which in this area includes a height of at least the 1955 flood. Those banks would conpJetc)y surround the proposed working area except I where faced against high ground.

FJnodiog of such excavations would provide.a possible source of river contamination- by erosion of loose materia).s I overburer, or spoil. The Pei- mian coal measures zediments in particular, contain some saline material. As such, no stockpiling of materials other than those being used to create levee I banks should take place on the flood plain. The levee construc-. tion materials should not include rock spoil derived from the Permian sedirnent.s excavated from any open cut. Ll Rep] acement and re-establishment of significant aqui fers would involve separate stockpiling of the major alluvial unics determined from soil profile studies so that they cou-ld be replaced in their original sequential order. Such repJ.acemen I would require concurrent development of adjoining discreet open cut units allowing continuous re-placement of materials in each open cut after coal extraction has taken place. This procedure would limit stockpile areas and ensure timely progressive res- I toration of an area.

Eventual replacement levels are recommended at half 1 a metre above original surface to allow for expected settlements and bring the surface profile as near as possible to original surface levels in order that existing flood regimes might be maintained. In order to improve- flood characteristics, 11' some variation of th-ese levels may be approved. The monitoring and control of pollution demands a firm clearly designed programme. Water pollution is probably the Li major environmental hazard but the Committee is confident that pollution problems can be controlled effectively by careful design. The provision of effective drainage systems for the surface workings is essential. It is desirable for instance to I intercept agriculturally important good quality aquifer waters before they are contaminated by contact with open cut material. All saline waters should be restricted to the coal lease area and discharged only in accordance with the requirements of the Clean Waters Act. I Re-established aquifers will need to be assessed for effectiveness and performance This could be car - ried out by means of observation and pUmping bores placed within the replaced material. Monitoring of such bores would need to I be carried out to assess the effectiveness of the restorat ion. I 34. I 11' Sequential replacement of topsoil and the underlying would need to be specified in order to re-establish agricultural

potential of the land. Establishment of trial crop areas would Li be necessary to determine the effectiveness of restoration of the land and its productivity. Li The Committee believes that it is possible to effectively restore mined lands in alluvial areas to their original agricultural potential. Such restoration will be expensive and much more costly than open cut or strip operations away from the I flood plain but is necessary to ensure the continued environmental and agricultural amenity of the riverine areas.

I INVESTIGATIONS- CARRIED OUT IN THE BUCHANAN LEMINGTON AREA The Committee on seeking to obtain actual and empiri- Li cal data on mining of shallow coal within alluvial lands has found that local and overseas experience is not relevant to the climatic and agricultural regimes of the Upper Hunter Valley. L Because of the lack of relevant data the Committee during 1978 sought to define areas of the Hunter Valley from which data might be obtained to develop parameters whereby the impact and feasibility of mining in alluvial lands might be I more scientifically assessed and the impact of mining might be evaluated wiLh minimal possible risk to the environment.

The Committee decided that such an area should have El the following characteristics.

Be limited in size to a email operation.

I Be underlain by alluvial sediments and coal measures sediments which represent a typical geological section LI suitable for mining, Contain reasonable aquifers within the alluvial sequence.

Pose minimal or relatively minor environmental problems, [Ti if mined. 5. Have minimal effect on present land usage. Li Be reasonably isolated from other mining activity and potentially cumulative environmental effects.

Not be located near populations concentrations or Li public roads.

Be capable of being "restored" to its original produc- I tivity in a minimum period after mining usage. 9. Could be carefully and scientifically monitored after such restoration, without interference from future I mining activity. A number of areas were assessed and a section of river- me alluvial land within the Buchanan Lemington Colliery holding I was considered to be the most appropriate area in which scientific assessment and trials could take place and be carefully monitored with minimal environmental disturbance.

I The area forms part of Portions 142 and 136 Parish of Lemington, County of Hunter, and consists of approximately 30 hectares of rjverjne alluvial land situated on the west bank of the Hunter River. The land is privately owned by Buchanan Bore- I hole Collieries and has not been used for agricultural production for some years. An old disused dairy is located west of the site. The general location of the area is shown on FigureS. I I 35. H I

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SHOWING I LOCALITY OF PROPOSED 5 EXPERIMENTAL MINE AREA I I 36. The company originally intended to work this area as a normal extension of their then existing, open Cut operations Li but changes to the Regulations of the Coal Mining Act and appli-- cation of policy restricting development on the flood plains, stopped any mining development.

I The company has since applied to the Department of Mineral Resources for approval to commence mining operations on the flood plain.

Li The land is underlain by alluvial sediments and at shallow depths by potential open cut coal belonging to the Mt Arthur/pjercefjeld Seam Complex of the Wittingham Coal Measures. I This comprises soft coking coals similar to those worked at Buchanan Lemington and other nearby Collieries. The area has been drilled by the Colliery in previous years and results indicate that approximately 8 million tonnes of coal could be I extracted from the alluvial area west of the river.

The Committee examined data available on this area and concluded that further studies would be desirable to assess the I suitability of the site as a possible trial mining area in which mining and restoration might be closely studied to provide data and develop parameters to preclude any short or long term environmental problems which ]arge scale mining of alluvial areas I might cause.

Further studies have been carried out on the Buchanan I Lemington Colliery area and these have included determinai:ion of soil profiles and characteristics; the quality of surface and underground waters, and the determination of aqui fer propertIes within the alluvial materials blanketing the site. Li Soils Investigations

Detailed investigations of both the alluvial and under- [1 lying Permian Soil Measures sequence were carried out within the 30 ha area by two series of drill holes drilled by Buchanan Lemington Colliery to investigate the alluvial sequence and underlying Permian coal measures and to assess the groundwater Ii potential of the area of potential mining.

The Soil Conservation Service of New South Wales carried out soils investigation and preliminary groundwater obser- I vations for the colliery company and the committee, based on a series of 6 bores drilled along a line parallel to the Hunter River and roughly through the northern/central sectdr of the LI proposed mining area. The location of these bores (Soil Test bores) and Li original company drilling are shown on Figure 6. During initial company drilling, no sampling of the alluvial material was undertaken, the later 6 bores were drilled through the alluvial sequence to the coal measures sediments. I Alluvial material and samples of the basement rock down to a depth of 59 metres were recovered by a combination of coring, auger drilling and diamond drilling. A small section at the base of the alluvium, ranging from 1.5 to 3.8 metres thick, I could not be recovered by any of the drilling methods. Later drilling confirmed that this section was water bearing.

The drilling showed that within the area the stratigra- I phy of the alluvial sediments was quite Consistent. The general- ised sequence present in the area is as follows:--

-J I I 37. I I I L] • LI / (i /.' / N L[; ;;Ui Ci S l CUT I If( tLr! r I\j 1 /. 0 SI ,...

..... ...... I [ \ \ s zi \ . -/ \•\ \ \ . ...... - I A \\ \\.\\ I So ur lic D:rncj cs ill ...... - I / 1 > ) \ SG I ( I 1_ 'I I \ \\ \ ' \ . N,.. ., I / I . ... . ... - '_,/ ;. r•. I /

I I I 38. 1.5m Topsoil, dark brown.

I 8.5m Clay, dark brown.

2.4m - 4m Gravels, sands with interbedded clay.

I Perrnian sediments, weathered,

The upper alluvial and topsoil horizons within the Li area are particularly consistent in thickness. The sandy- gravelly layer varies in thickness throughout the area also in water content. The bottom part of the alluvial sequence is an aquifer which is poorly developed in the northern part of the [1 flood plain but improves to the south.

A characteristic of the sequence is that clay content of the alluvial materials above the aquifer layer tends to in- I crease gradually with depth.

Salinity determinations were carried out on both soil and groundwater samples and none of tile materials intersected I Present any problems of salinity.

On the bases of these studies the Soil Conservation Service made a series of recommendations relating to possible I mining of the site. These relate to

i Selective Removal ofOverburden (including progressive I restoration of any mining operation in a cyclic way). The service divided the materials into topsoil, alluvial materials and undisturbed rock. Later more detailed I investigation proved the presence of significant groundwater in the area and the need to subdivide the soil profile into 5 divisions, that is, topsoil, growing horizon (l-m), unclassified alluvium, aquifer material I and rock material. I Composition of Fill Material The service estimates the average swell factor applicable to the backfilling of the excavation is between 17 and 30% averaging 24.3%. This is an important I consideration in restoration of the surface to near its original level and profile to minimise the effects of flood flows and soil erosion. The fill bulk density should be as close as possible to the undisturbed 1 alluvial material. Reveqetatjon Methods

I The alluvial flats are capable of supporting good quality vegetation and the Soil Conservation Service suggest field trials be carried out on any restored 1 areas. The original report of the Soil Conservation Service of New South Wales is attached as Appendix II. Conclusions and I recommendations of the report have been in part modified by later data particularly that obtained during later drilling. The main modifications relate to the proven presence of aquifers confirming the area as more representative of other areas of I the Hunter Valley alluvials than the report suggests and the necessity in the view of the Committee that selective replacement of aquifer material would form an integral part of any I mining operation. I I 39. SLIRPA CE AND GROUIVDWA TEE INVESTIGATIONS LI Floodfng Protection of any proposed mining operation, on the riverine flats from flooding, is essential both for safety considerations and - to avert the possibility of open cut material I being workeddowns.tream.

Flooding would no doubt cause problems in large scale I open cut mining on the floodplain. ,Prdblems could be expected in the mining operation itself, but in a.ddi'ion, the mining operation could adversely affect other users of the flood plain I during floods. The possibility of the flood waters becomirg polluted through contact with stockpiled material or the open cut workings; and also the possibility of the flow of flood waters I being affected by access roads or railways, .or by any other enibankments or structures associated with the mining must be considered The flood plain plays an important part - in carry-- I ing flood waters, and any obstructions to the flow could resu)t in ]flCreased fJood levels, increased flow vcjocities with atten- dant erosion or the redjreccjon of waters away from their usual I path to other areas. No stockpile or.perr,anen ConstruQtjon works should he located olL, ' he flood lai:r ..ecanse of this reason. I The question of levee bank's around the Buchanan Lemington trial mining area has been examined by the Water Resources Commission. A levee surrounding the proposed excavation would have no significant effects-in increasing flood I levels on other lands, or on increasing the velocities of flood waters. In 1 955 flood conditions (the maximum known flood), the area to be surrounded by the levee - would have carried no more than 20 percent of the total flood flow. If ..the levee had been Li in existence, it would have caused an increase in flood levels of only about 30mm.

Li It has been estimated also that the difference between the levels of a one-in-twenty_years flood and the 1955 flood would be less than 1 metre.

I In view of this, and-the merits of le.veeing the excavation, The Water Resources Commission has recommended that if approval is given to 'i:he mining proceeding, the Company should be required to construct a levee around the site of the excava- I tion with its crest level no lower than the level of the 1955 flood in this area. The 1955 flood reached a level of 59.Sm A.H.D. at the upstream end of the site and 58.8m at the downstream end.

It would be necessary for the Company to make application to the Water Resources Commission for a licence under the I Water Act to construct such a levee. Groundwater Inves tigations I Initial investigations by the Colliery company and the Soils Conservation Service led to a confused picture of the groundwater regime in the Buchanan Lemington proposed trial area. These early programmes reportedly encountered no groundwater. I However many of these bores were located in the northern half of the area. I I I

Local inquiry indicated that the alluvium does contain an irregularly developed poorly ycilding aquifer which until the I 1955 flood has been tapped by at least two wells to provide irri-- gation water. These wells were located near the river hank and probably silted up during the flood. Present mine supplies and those for the Nichol's property to the south are drawn almost I directly from the Hunter River. The Water Resources Commission undertook to assess *the groundwater potential of the area. This was financed by the I Colliery company. An assessment was prepared (Roberts and Gates 1979) which is included as Appendix III of this report.

In all, ten bores were drilled by percussion methods I throughout the area. The bores penetrated the full alluvial sequence and a short distance of Permian strata beneath it. Five test bores were completed to observation bores (30732, 30734 I -30736, 30740) in order to monitor water levels and water quality. Four bores (30731, 30737-30739) failed to encounter sufficient water to warrant conversion to observation holes. Significantly these bores are located in the most northern section of the area I and at its central western margin. :. Locations of the •bores and of well No. 1 are shown on Figure 7. A series of 24 hour pumping tests were carried out I on bore 30733 and well No.. 1 in the central southern part of the area, Aquifer test results were assessed by computer analy- sis. Water sampJe quality, was analysed for both the alluvium I and underlying permian sediments. The results of the investigations are detailed in . Appendix II. In summary, the programme has shown that much of I the southern and central section of the area will be underlain by a single aquifer recharged by the Hunter River. Wells in Ihe area could be expected to yield moderate supplies of groundwater in the range of 5 to IS litres/sec (5000-15000 gal/hr)

The northern and western sections of the area furthest .. from the river contain little groundwater.

I The upper parts of the aquifers contain low salinity water. Salinity generally increases towards the aquifer base and the Permian sediment contact.

I Numerical modelling tests indicate that expected groundwater inflow to a total excavation could be considerable at times of high flow of the Hunter River. The calculations however, are based on an excavation face exposure of 1.448 kms I but the maximum exposure under cyclic mining operations would be in the order of 600m and equivalent maximum inflows of 12,000 to 29,000 m 3/day and minimum in times of low flow, a normal situation for the Hunter River, of 400 to 1600 m 3iday. I This quantity of water could be easily handled by normal pumps.

A further important conclusion of the report is that I restoration of the aquifer material to a similar situation to the present should be possible if careful stockpiling and re- .placement techniques were observed during any mining operation. I The Suitabiliti, of the Buchanan Lemington Site as a Controlled Test Area

The Committee believes that on the basis of the studies I carried out that the Buchanan Lemington "cast cut" area will provide a suitable experimental area where limited trial surface mining operations and restoration can be carried out in a finite period without posing significant long term environmental hazards. 11 ------

30740 A

A30738 / N 30737 .1 N 30734 /30732/ - N / / 1

/ f /3.735 / 3073

Q Wfl 630735 wAiro 7 HYDROGfOLOG(A1 STCTION - WTTR R1SO.JRaS / GROUNDWATER INVESTIGATION OF MINING PROPOSAL NEAR COMIEROI - / LOCATIONS OF TEST BORES & SEGIONS / 4I loo o

-- - ------r- ------I A carefully controlled and limited trial mining operation under stringent carefully controlled mining and environmental conditions will provide an opportunity to collect I invaluable data and experience which will lead to a much clearer definition of the Principles and controls which might be applied if larger scale mining of other areas of the riverine alluvial plain is to be considered in the future. I Any trial operation would be subject to environmental legislation applicable to normal surface mining, restoration of original hydrogeologicai (aquifer) and agricultural potential I and the prevention of pollution. The effectiveness of restoration will need to be carefully monitored and assessed by field trials and studies carried out during and post restoration of the surface. The studies, particularly those relating to restor- I ation of groundwater potential will need to be carried out over a sufficiently long period of time to gauge aquifer response to different river recharge levels and establish, if any, pollution Sources. Agricultural yields will need to be assessed by moni- I tored trial plot.

The basis of any trial operation is restoration of I groundwate r and agricultural potential of the area at least to that determined prior to mining.

The Committee suggests that tile following conditions I should appJ.y to the proposd. surface excavation on the alluvial flood plain.

Ai' excavation should be protected by a levee bank or I banks acceptable to the Water 1esources Commission. This bank should fully enclose any excavation or earthworks until the surface has been restored to the specified level. The crest level of such a bank must at least be that of the 1955 flood which on the Buchanan Lemington property reached levels of 58.8m A.H.D. at the downstrean end and 59.5m A.HD. at the upstream end. The levee should be constructed of alluvial materials not of rock: I spoil derived from the excavation. The levee bank would need to be systematically removed after restoration of surface mined materials either for excavation filling or surface restoration. I The excavation would be required to be backfilled in the sequence of layers identified during the soils investigation. These are

Unclassified rock fill to the level of the overlying unconsolidated sediments. The emplaced fill would need to be partly consolidated by tracking and grad.- ed to even levels.

The sand/gravel aquifer would be placed above this rock fill as near as feasible to its original position.

Unclassified alluvial material (comprising the bulk of the alluvial sequence) would be placed above this layer.

1 metres of the alluvial material directly beneath the topsoil would be placed to approximately the same bulk density as it was prior to removal, above the unclassified alluvials,

the top 30 cm of topsoil would be placed above this layer. I I L4 3

H \

I II I I I I I I I Lii LI I I I I I I FIGURE 8 I

I Surface contours of the area should be restored to a level approximately i metre above the original contours to I allow for limited settlement expected. The surface topography especially flood channels should be restored. Periodic surveys should be carried out to monitor any consolidation which might I occur in the area. All defined classes of materials from the excavation I should be separately stockpiled away from the river flood plain. No excavation should extend within 40 metres of the top of the river bank taken at ground level.

I The pumping bore 30733 and observation bors 30740, 30736 used to assess aquifer characteristics of the unmined area should be protected during excavation for monitoring pur- Poses. All other observation bores in the area proposed for I mining should be protected until excavation of any unit area is imminent Further bores will need to be emplaced over the restored areas to monitoi' the effectiveness of aquifer replace. I ment and to assess water quality. The final surface should be restored to Pastures as directed by the Soil Conservation Service of New South Wales. The Department of Agriculture should undertake trials to deter- I mine whether the restored land will support deep rooted plants, such as lucerne, to an equivalent state of productivity as adjacent lands. The Water Resources Commission and the Department of Mineral Resources and Development will co-operate in ground- I water testing and monitoring.

I THE BUCHANAN LEMINGION EAST CUT PROPOSAL Buchanan Lemington Colliery, in lte tailed assessment of coal 1977, began de- named its ea occurrences in what the colliery has I st cut which embraces alluvial areas on the west bank of the Hunter River. The Company has defined approximate ly 8-9 million tonnes of Predominantly soft coking coal of the Piercefie1d/jt Arthur Seam Complex alluvial lying beneath I0-13m of I sediments in a triangular shaped strip, 30 hectares in area, pdjaccnt The to the river. The area is shown in Figures area,js private land underlain by private coal. In 1977, the company partly owned the area and has subsequently purchased I the remainder. Plates S and 6 are views of the area looking in a south easterly direction.

the Coal MinesIn May, Regulatio 1978, Regulatj0 55 of the 8th Schedule of I n Act was amended so that Ministerial collieryconsent isho1diig required for any new open cut proposal within a Prior to this amendment, mining could have I ingcontinued Operations under OXisting approvals as a continuation of exist-

open cut The colliery Subsequently has applied to commence I o perations in this east cut area which coincides with the area the committee proposes for a trial mining operation durinThe committee held discussions with Buchanan Borejioje Collieries g and subsequent to IflVestigatj05 carried out on the area I and the company has since indicated its preparedness to carry out mining operations on a experjjflfl01 basis to the standards and conditio115 required by the committee and set by statutory authorities Company has putNi th its app I i cation for approval to mine, the I methods forward a set of Proposals it would use to mine the area. illusti'ating the

The Company in these proposals has pointed out that I it has planned to mine in SUCh a h way that t is not dependemit upon coal from the area to fulfil its immediate aret reqlmirc nents and regards the Smll u m k I One only . g operation proposed s an I I 45. I I

FORM I lOPOIL STORAGE /TO5Q1TO L TO 0 1 I' OPTH, LCOL TO 5TO I RCMAINOCR WAbHI PLA NT I STIL 5UOIL (05 t il I TO STORAGE I

I NcLAcIcIo TO LEV(E 610C K PIL O r TO S1O.KC I E'KG I TO TOCkPj ;TP 2

TOpOlL TO I I I 6UOu. TO - I I I I I 1 1 1 I I I I FIGURE 9 I

I I 46. LI I

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I VO$OIL . '1.

- V I k44 I

V I Svial P C0AL IHI PLAWT V \ \\ VQAcciLL V

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I FIGURE 10 I I 47 . I -. -a I -- - I Ll I Liii 0 F

I "a I cc z (0 L 2 2 STdb co I 0 I ii— /

I I COAL Ya INC PLAIiT - • gO ICIA1.0 NING LJRON / I STRIP a /

I TOPSOIL To 1 SUOL TO STRIP L__i I L I I I I

- ------••-.,...—,--- I __••;- -. —.'--- =- - —

I FIGURE 11 I I 48. Buchanan Borehole Collieries' proposals follow closely the recommendatjojs of the committee. The Company has divided the 30 hectares I operation into a series of small discreet 2-3 hectares mining units which would be mined by existing colliery equipment. Excavation and restoration would mainly be a truck and shovel operat-ion utilising only minimal blasting. I Restoration wbuld be carried out progres- sively as mining proceeds. The mining area will be fully protected by a levee bank, approved by the Water Resources Commission. Figure 8 shows the proposed plan of working. I L The Company has agreed- that selective excavation and restoration methods would be used in the mining operation. It has agreed that the I five units defined by the committee on the basis of previous exploration can be feasibl.y mined and replaced, including the aquifer material. The Company has agreed that these materials would be separately stockpiled in areas away I from the flood plain and would be replaced pro- gressively back to the excavation in a cyclic fashion. All materials would be replaced to approximately the same bulk density as they came out of the grouid. Restoration would be I carried out under recommendations of the Soil Conservatjon Service and the District Inspector of Collieries.

The Company has proposed that existing drainage, I i.e. the billabong, old flood channel in the western side of the area should be undisturbed by mining and utiiised as a Storage area for : excesssurface runoff.. This water would be pumped by pipeline to the Colliery holding and utilised for I 4 washer)' purposes. Any water encountered or entering open cut excavations would 1 be similarly pipelined to the colliery I holding. The Company has proposed to backfiJ.l the coal face section of the open cut workingswjth consolidated washery reject material, which in turn would be covered b.y the un- I classified rock fill.

Figures 9, 10 11 show the sequence of mining proposed by the Company. Appendix IV contains the company proposals for mining I and the accompanying figures illustrate drainage proposals, cross sections and the proposed restoration levels for the area.

Appendix V details the special conditions which the Committee believes should be imposed on the experimental . mining operation if I this takes place. The Company has indicated that they wold seek no variation of the plan unless it was discussed with Committee representatives. I I 1 I I I H

I i

I P L A T E S '1 I II il I H' I F I

I( I

LIST OF PLATES

Plate 1 hUNTER RIVER ALLUVIAL FLATS NEAR JERRYS PLAINS

Plate 2 VIEW OF ALLUVIAL LAND NEAR ARCHERFIELD

Plate 3 VIEW OF ALLUVIAL LAND NEAR ARCI-IERFIELD

Plate 4 VIEW OVER ALLUVIAL PLAIN EAST OF COAL 4 ALLIED INDUSTRIES AUThORISATION A13

Plate S BUCHANAN LEMINGTON COLLIERY PROPOSED TRIAL OPEN CUT AREA

Plate 6 BUCHANAN LEHINGTON COLLIERY PROPOSED TRIAL OPEN CUT AREA

Plate 7 WARKWORTH AREA PRE MINING SALINE DRAINAGE

Plate S STRIP MINING RAVENSWORm NO. 2 OPEN CUT

Plate 9 PROGRESSIVE REHABILITATION HOWICK OPEN CUT

Plate 10 GAUGING BAYSNATER CREEK

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I PlATE 4 VIEW OVER ALLUVIAL PLAIN EAST OF I COAL & ALLIED INDUSTRIES AUTHORISATION A13 I •

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