10NITORING I THE BENNELONG DRAIN I SYDNEY,...

I I I I I I I I I I I I I I I I I I I I I

REPORT ON ARCHAEOLOGICAL l\10NITORING

THE BENNELONG DRAIN

SYDNEY, NSW.

A Report Prepared for T. \V. Crow Associates

November 1991

WENDYTHORP

I I I I I

! I

1I !

I I I I I I I I I I I I I I

REPORT ON ARCHAEOLOGICAL MONITORING

BENNELONG DRAIN

SYDNEY, NSW.

AREPORTPREPARED FOR T.W. CROW ASSOCIATES

NOVEMBER 1991

WENDY TIIORP

CONSULTANT ARCHAEOLOGIST

I I

i I

I I il

I I I I I I I I I I I I I I I

ARCHAEOLOGICAL MONITORING: BENNELONG DRAIN, SYDNEY

CONTENTS OF THE REPORT

1.0 Synopsis .................................. 2

2.0 Introduction to the Report ....................... 5

2.1 Location. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.2 Parameters of the Investigation .................... 5

2.3 Initiative for Investigation ....................... 5

2.4 Status of the Site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2.5 Objectives ................................ 6

2.6 The Construction Programme ..................... 6

2.7 Methodology ............................... 7

2.8 Authorship and Acknowledgements . . . . . . . . . . . . . . . . . . 7

3.0 Historic Context ............................. 8

4.0 Archaeological Evidence ........................ 9

4.1 Construction Methods: The Tunnel, The Drain & Work Practices 9

4.2 Construction Materials .........................11

5.0 Subsidiary Documentation ....................... 12

5.1 Endnotes ................................. 12

5.2 Bibliography ............................... 12

Pagel

I I , I I I I I I I I I I I I I I I I I I


SECTION 1.0 SYNOPSIS

Location and Parameters of Investigation

This investigation was concerned with a section of the Bennelong Drain within Bennelong Point, Sydney that partially underlies NSW Government House and the Opera House forecourt. It related to the archaeological evidence that was likely to be disturbed or removed by the programme associated with the construction of an annular car parking chamber, entry and exit ports and fire escape tunnels. It has been carried out on behalf ofT. W. Crow and Associates and has arisen from recommendations made in the archaeological assessment prepared for this site.

Objectives and Methodology

The primary objectives of the work were to monitor the course of the construction programme in those areas where the Bennelong Drain was directly affected, to record evidence of both construction methods and materials utilised in the drain and to provide a permanent archival record of this information.

The only sections of the drain completely removed during this programme were those at the northern and southern contact points, removed for the bulkheads and diversion, and the section occupied by the main annular chamber. The drain on either side of these areas was not damaged.

The site was visited at regular intervals and whenever a new section of the drain was exposed. Recording was carried out by means of photography and measured drawings.

Historical Context

During the first half of the nineteenth century the development of the city led to the pollution of the streams which had originally provided water for it. The construction of underground sewers became imperative. It was not until 1857, however, that work commenced on this programme.

The project encompassed the construction of a number of major brick and stone outfall sewers with minor sewers leading to these in nearly every street and watercourse. The outfall sewers were completed in 1859. There were five major lines of which the

Page 2



Bennelong or "Port Macquarie" system was one. The drain continued to be a principal stormwater system until the 1950s. Subsequent diversions, modifications and construction of new sections have taken place since the 1960s. Major interruptions have occurred for the construction of the Opera House with one section being diverted in the forecourt.

Archaeological Evidence for Construction Methods

The archaeological material uncovered during this programme has revealed clear evidence for the techniques used in the construction of the drain as well as associated work practices.

The first stage of construction which prepared the site for laying the drain consisted of the excavation of a tunnel through the bedrock. The tunnel measured approximately 2.5 - 3.5 metres wide and had a bell shaped section. Evidence recovered from the site indicates the use of explosives in its construction. In addition to these, however, it is clear that quantities of rock were removed manually and evidence suggests the use of modified tools for work within the confined space of the tunnel.

Other evidence recovered during this programme suggested the use of wagons or skips for the removal of rubble from the work face. This may also have been facilitated by the introduction of a vertical shaft. This feature was roughly circular in plan with a diameter of approximately 1.8 metres. It appears to have originally been connected with the surface and it may have provided both access and air as well as providing a short and efficient route to the surface for the removal of spoil.

Other features were identified and recorded that provided evidence for the work practices that were employed and the conditions that prevailed during the construction programme. In particular, in one area, a chamber at least six metres across and two metres high had been formed in the tunnel. It appears to have been a deliberate construction element and it may have been used as a rest area during the construction of the tunnel and drain.

Mter the completion of the tunnel construction commenced on the oviform drain. Construction of the drain was carried out in two courses of brickwork laid in stretcher bond without any cavity. No variations in shape were observed in the section of the drain that was examined in this programme and no inlets or spur lines were located in this section of the drain.

It appears likely that it was constructed in short section over a framework set up within the drain. As each section was completed sandstone rubble was packed into the void between the tunnel wall and the external surface of the drain. In the area of the vertical shaft the sandstone packing was carried up to the shoulder of the vault. This indicates that some packing took place during the construction of the vault.

There was no evidence for any changes or modifications having been made to the drain since its construction. No damage to the structure was observed and only a small amount of salt bloom was found to be present on the arch.

Page 3

I I II I I I I I I I I I I I I I I I I I I


Archaeological Evidence: Construction Materials

The bricks used in the construction of the drain were found to be well fired, hand moulded sandstocks with shallow rectangular frogs. They were bonded with a brown patent cement. A similar cement was used as a render on the floor and the lowest part of the walls within the drain. The render made the drain water tight and prevented scouring of the softer brick walls. The cement is not like other renders and mortars commonly used in building works of the 1850s in Sydney.

Page 4



SECTION 2.0 INTRODUCTION TO THE REPORT

2.1 Location

This investigation was concerned with a section of the Bennelong Drain within Bennelong Point, Sydney. This section of the drain partially underlies NSW Government House and the Opera House forecourt as well as land in Macquarie Street North.

2.2 Parameters of the Investigation

The investigation related to the archaeological evidence that was likely to be disturbed or removed by the construction programme. This evidence may be broadly defined by the relics provision of the NSW Heritage Act (1977, amended 1987) being;

"any deposit, object or material evidence relating to the settlement of the area that comprises New South Wales, not being Aboriginal settlement; and which is fifty or more years old. 11

2.3 Initiative for Investigation

This investigation has been carried out on behalf of T. W. Crow and Associates. It has arisen from recommendations made in the archaeological assessment prepared for this site viz:

"th at a watching and recording brief be initiated for the excavations in Macquarie Street North (and the Opera House forecourt) with sufficient time to be allowed for the investigation and recording of any features, relics and deposits considered to be of significance by the attending archaeologist.

"that a detailed record is made of the section of the Bennelong Drain prior to its removal. This should include plans, sections and a photographic record.

"that a detailed report on the programme be prepared in accordance with the provisions of the Excavation Permit" (1)

Page 5



2.4 Status of the Site

The site was not encompassed within an existing conservation instrument at the time of the investigation although features and relics of significance were mown to exist. In addition to the archaeological assessment a number of historical reports and assessments had been prepared which had relevance for this site. These works are noted in the bibliography.

2.5 Objectives

The primary objectives of the work were defined as follows:

• to monitor the course of the construction programme in those areas where the Bennelong Drain was directly affected

• to record evidence of both construction methods and materials utilised in the Bennelong Drain

• to provide a permanent archival record of this information

This report fulfills these objectives.

2.6 The Construction Programme

Construction of the Bennelong Parking Station required the excavation of an annular chamber with entry and exit ports and fire escape tunnels. A section of the Bennelong Drain needed to be removed for this work. The drain is still an active stormwater conduit and for this reason a diversion had to be constructed that linked the northern and southern sections of the drain bypassing the chamber.

The only sections of the drain completely removed during this programme were those at the northern and southern contact points, removed for the bulkheads and diversion, and the section occupied by the main annular chamber. The drain on either side of these areas was not damaged. In relation to the locus points of the construction works these may be defined as follows:

• south of point [51208850] the drain is intact

• a section approximately five metres long was removed north of this point for the bulkhead

• the drain is intact north of the bulkhead to point [51258880]

• at point [51258880] it was cut by the annular chamber

• between points [51258880] and [5148945] the drain has been entirely removed

• a small section remains intact between points [51458945] and [51478955]

Page 6



• a three metre length of drain was removed north of [51478955] where the bulkhead was constructed

• the drain remains intact north of this bulkhead.

2.7 Methodology

The site was visited at regular intervals and whenever a new section of the drain was exposed. Recording was carried out by means of photography and measured drawings. Access was provided by T.W. Crow Associates who also provided assistance during the recording work. T.W. Crow Associates also supplied instruction in safety procedures relating to work in confined spaces.

Contact with the drain was made at the following locations:

• during the excavation of the fire tunnel and the diversion line at the southern end of the site; location [51208850]

• during the excavation of the northern section of the diversion line; location [51498952]

• during the lowering of the floor of the main chamber. This caused a breach in the roof of the drain; it was subsequently removed. This was at location [51358910-51408920] and [51458945].

During this operation the drain was sectioned in a number of places. This provided opportunities to examine the fabric for evidence of changes in construction and form.

2.8 Authorship and Acknowledgements

This report has been prepared by W. Thorp the principal consultant for the project. The field work and recording was carried out by Mr G. Wilson. The author would like to thank T.W.Crow and Associates and the Sydney Water Board for their assistance during this programme.

Page 7

I I I I I I I I I' I I I I I I I I I I I I

OJJAV EAst ..... I , I I

• • ,

, .....

\

• .-:. I-~ /1 .;. \.. ... "\ l.!~"'if ,/

C f\\ J"''''''"\ "t't' ) \,._ t.. .. \ ............. . ...... \. .. ,.) ........... J .... ot\.. 1

r"··J ... ·_f~" .. f ("'-\~'" \:..... . ....... 1 Government House

'\ , ..... ....... #. • ., •• -

\,-.... iI ...

FIGURE 1: Location Plan - subsurface construction shaded.

I

\II I I I I I I I I I I I I I I I I I I


SECTION 3.0 HISTORIC CONTEXT

During the first half of the nineteenth century the development of the city led to the pollution of the streams which had originally provided water for it. The construction of underground sewers became imperative. After the election of the Council for the newly declared City of Sydney in 1842, the provision of proper surface and underground drainage emerged as a priority. It was not until 1857, however, that work commenced on this programme.

The project encompassed the construction of a number of major brick and stone outfall sewers with minor sewers leading to these in nearly every street and watercourse. The outfall sewers were completed in 1859. There were five major lines of which the Bennelong or "Fort Macquarie" system was one. It was described as:

"Fort Macquarie, brick, 6-ft. by 4-ft., oviform, with branch oviform sewer 3-ft. 6-in. by 21t. 4-in. from Bridge Street ad other tributaries discharging into Sydney Harbour at Bennelong Point." (2)

These sewers were laid generally nine feet below the contemporary surface and at first carried stormwater, surface drainage and sewerage. Eventually fouled water and drainage were separated with the old sewers servicing the run-off. The Bennelong system ran past Fort Macquarie into the reclaimed area which, by that time, had caused the Fort to become land locked. The drain continued to be a principal stormwater system until the 1950s. Subsequent diversions, modifications and construction of new sections have taken place since the 1960s. Major interruptions have occurred for the construction of the Opera House with one section being diverted in the forecourt.

Page 8


Bennelong Drain

, ,

'Di

[ ~ ... : ·-1-

,' .. " "

. ::' .. , .' .: '. , . " . " .! ,.

: .. " 0:" " •.

'/:~/ "

, .. ~ , .. '",,,""' .... ",; ...... , .

~ .. ':1 ."

FIGURE 2: Portion of 1865 sUNey showing Bennelong Drain in relation to Fort Macquarie and Government House (Source: 1865 Trigonometrical SUNey of Sydney - Sydney Water Board)

I I I I I I I I I I I I I I I I I I I I


SECTION 4.0 ARCHAEOLOGICAL EVIDENCE

4.1 Construction Methods: The Tunnel, The Drain and Work Practices

The archaeological material uncovered during this programme has revealed clear evidence for the techniques used in the construction of the drain. In addition, information has also been recorded that relates to the working conditions and materials used in the drain.

The first stage of construction prepared the site for laying the drain. This work consisted of the excavation of a tunnel through the bedrock. The tunnel measured approximately 2.5 - 3.5 metres wide and had a bell shaped section. Drill holes found in the roof and walls of this tunnel indicate the use of explosives in its construction. Additional evidence of this method of excavation was provided by the quantity of shattered sandstone fragments which were later used as packing around the brick drain.

In addition to the use of explosives, however, it is clear that quantities of rock were removed manually. Tools were located in a section of the tunnel that provide evidence of this activity; a pick head (BD001), a shovel (BD002) and a bar (BD003). The short length of the pick head (500mm) suggests the practice of using modified tools within the restricted space of the tunnel.

Further evidence for the actual method of work was provided by the presence of cast iron wheel fragments (BD004-BD005). These items infer the use of wagons or skips for the removal of rubble from the work face. This evidence implies that the floor of the tunnel was either lined with timber or dressed to a smooth surface to allow for the passage of these wagons or skips.

Removal of rubble may also have been facilitated by the introduction of a vertical shaft. This was located at [5138.374 8924.523]. This feature was roughly circular in plan with a diameter of approximately 1.8 metres. The shaft had been filled with red-brown clay and a smaller proportion of sandstone rubble. This shaft appears to have originally been connected with surface and it may have provided both access and air as well as providing a short and efficient route to the surface for the removal of spoil. It is also possible that it may have helped with the engineering aspects of the project perhaps acting as a sight line for the direction of the tunnel much as Busby did with his bore.

Page 9

I I I

i I

I I I I I I I I I I I I I I I I I


It is possible that a number of similar structures were located at regular intervals along the course of the tunnel. In this deeply sited section of the tunnel through bedrock the open cut methods used elsewhere in the city were unsuitable. Such a system would have allowed several gangs to be employed simultaneously along this length of the drain. It would also have prevented the circulation of stale air.

Other features were identified and recorded that provided evidence for the work practices that were employed and the conditions that prevailed during the construction programme. At the first point of contact with the drain [51208850] rubble packing was encountered at least four metres from its known line. Rubble fill had been removed only from the western side of the drain and it was clear that the tunnel had been widened during its construction to form a chamber at least six metres across and two metres high. The northern and southern extent of this feature was not discovered since the point of contact was designed specifically for the installation of a bulkhead and diversion.

This chamber appears to have been a deliberate construction element and not a variation caused by a realignment of the tunnel or through flaws in the bedrock. All of the artefacts recovered from the site came from the floor of this feature. They consisted of a mixture of tools and equipment and items associated with the consumption of food and drink. This may indicate that the chamber was used as a rest area during the construction of the tunnel and drain.

After the completion of the tunnel construction commenced on the drain. The drain is oviform and was found to have internal measurements of 1.82 metres in height, 0.4 metres in width at the base of the channel and 1.21 metres width one metre above the floor. The drain has a fall to the north although the precise gradient could not be calculated during this work.

Construction of the drain was carried out in two courses of brickwork laid in stretcher bond without any cavity. Slight variations in bonding that were observed on the external surface of the vault suggest that it was constructed in short section over a framework set up within the drain. As each section of the drain was completed sandstone rubble was packed into the void between the tunnel wall and the external surface of the drain. This void generally measured between 400-800mm except in the area of the chamber.

The shape of the drain may have presented some problems during its construction. The base and flaring tunnel walls appear to have been constructed in the tunnel void. The rubble packing may have been put in place after each course was laid to provide support for this free standing section of the drain. In the area of the vertical shaft the sandstone packing was carried up to the shoulder of the vault. This indicates that some packing took place during the construction of the vault. The remaining clay fill in the shaft was dumped from the surface following the completion of the vault.

No variations in shape were observed in the section of the drain that was examined between points [51388925] in the south and [51498952] in the north. No inlets or spur lines were located in the section of the drain examined during this project. There was no evidence of any changes or modifications to the drain made since its construction.

Only a small deposit had accumulated on the floor of the drain and most of this material

Page 10

I 1I

I I I I I I I I I I I I I I I I I I I


appeared to be recent building rubble washed in from the surface. No damage to the structure was observed and only a small amount of salt bloom was found to be present on the arch.

4.2 Construction Materials

The bricks used in the construction of the drain were found to be well fired, hand moulded sandstocks with shallow rectangular frogs. The dimensions of these bricks were: length - 230mm, width - 1l0mm and 70mm thickness.

The bricks were bonded with a brown patent cement. This cement was hard and durable although poor mixing had created some patches that consisted of almost pure brown clay. A similar cement was used as a render on the floor and the lowest part of the walls within the drain. Here the mixing was more controlled with a higher cement content. This resulted in a hard surface well bonded to the brickwork. The render made the drain water tight and prevented scouring of the softer brick walls. The cement is not like other renders and mortars commonly used in buildings works of the 1850s in Sydney.

Page 11



BENNELONG DRAIN CONSTRUCTION 1991

I Scale 1: 1000

I

line of diVerSiO\ ... ;;./

I I ,

I I , \ \

I

I 1

/ I

KEY

,-: ~ I Line of Bennelong Drain

I == ; I Section of drain removed

FIGURE 3: Location of Vertical Shaft and Sections of Drain Removed During Programme

GCW & WT 1991

----------------------- --

I I I I I I I I

1I

I I I I I I I I I I I I



FIGURE 4: East-West Section Through Bennelong Drain

GCW &WT1991 Scale 1 : 1000




East-West Section Through Drain and Southern Chamber

North-South Section Through Drain and Shaft

FIGURE 5: Sections Through, Drain, Chamber and Shaft

GCW &WT1991 Scale 1:50



PLATE 1: Vault of drain looking north at location [51308900]

PLATE 2: Detail of lower section of vault looking east

I I I I I I I I I I I I I I I

ARCHAEOWGICAL MONITORING: BENNELONG DRAIN, SYDNEY

PLATE 3: Shaft and drain below [5138918]

PLATE 4: Detail of shaft fill

I I I I I I I I I I ,I

I I I I I I I I I I

ARCHAEOWGICAL MONITORING: BENNELONG DRAIN, SYDNEY

PLATE 5: Detail of vault below shaft

PLATE 6: Profile of drain



PLATE 7: Lower section of drai n showing eement render

PLATE 8: Pick head



PLATE 9: Shovel head

PLATE 10: Section of wheel

I I I ,I I I I I I I I I I I I I I I I I I


SECTION 5.0 SUBSIDIARY DOCUMENTATION

5.1 Endnotes

1. Thorp, W.Archaeological Report Bennelong Point Parking Station.,

42. Quoted in Aird, W. The Water Supply Sewerage and Drainage of Sydney., 129

5.2 Bibliography

Aird, W. The Water Supply, Sewerage and Drainage of Sydney MWSDB., 1961.

Higginbotham, E. Archaeological Investigation of the Southern Approach to the Sydney Harbour Tunnel, The Domain Sydney, NSW Sydney Harbour Tunnel Joint Venture. 1989.

Kerr, J., Spearitt, P. and Proudfoot, H. Historical Background to Bennelong Point Colonial Mutual. ND.

Thorp, W. Archaeological Assessment Colonial Mutual Site Bennelong Point Planning Workshop. 1989.

Thorp, W. Archaeological Report Bennelong Point Parking Station Rankine and Hill Pty Ltd. 1990.

Page 12

10NITORING I THE BENNELONG DRAIN I SYDNEY,...

Documents

Transcript of 10NITORING I THE BENNELONG DRAIN I SYDNEY,...