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Diamond Mill, Manjimup
Diamond Mill was established by W.A. Chip & Pulp Co. Pty Ltd, commonly known as WACAP, on Eastbourne Road at Diamond Tree, south of Manjimup. It began operating in 1975, processing timber into woodchips for export through Bunbury. The mill continues to operate today as part of WA Plantation Resources (WAPRES).
Establishment
The project followed a State Government call for proposals to establish a woodchip export industry in 1967. WACAP was selected in December 1968 and established in 1969. Initially owned by Bunnings Timber Holdings, it later became a partnership with Millars (W.A.) Pty Ltd, which held a 40 per cent interest by 1973.
The Wood Chipping Industry Agreement Act 1969 provided for a mill near Manjimup, railway transport to Bunbury and facilities for loading ships. The agreement also required the company to investigate establishing a local pulp mill. Diamond Mill produced woodchips for overseas processing into pulp used in paper manufacture.
Difficulty securing an overseas buyer delayed the project. In 1973, the State Government reported that WACAP had negotiated a 15-year Japanese supply contract valued at $200 million. Amendments to the State agreement increased government responsibility for railway and port infrastructure and reduced the company’s immediate capital obligations.
Production and export
Woodchips were transported by rail from Diamond Mill to Bunbury. The State Heritage Office dates the first export shipment to 1976, while WAPRES identifies the first vessel as Hokuetsu Venture.
Marubeni, a Japanese trading company, entered into a supply agreement with WACAP in 1973 and later became an owner of the business. WAPRES now supplies woodchips to customers in Japan and China.
The early operation relied heavily on native forest timber, including marri and karri. An EPA assessment in 1988 listed the company’s timber sources as low-grade State Forest logs, regrowth thinnings, sawmill residues, private plantations and native vegetation on private land. Most came from State Forest managed by the Department of Conservation and Land Management (CALM).
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How the mill worked
A 1987 environmental report described logs arriving at Diamond Mill by truck. They were unloaded for immediate processing or placed in stockpiles. Logs were checked for charcoal, shortened where necessary and passed through machinery that removed the bark.
Large logs were cut into smaller sections before entering a chipper. Screens separated the chips by size. Oversized pieces went through another chipper, while very small particles were separated from the export chips. Bark was collected separately.
Finished chips were held in an overhead bin for loading into railway wagons. The report described a bin holding approximately 1,000 tonnes of freshly processed chips, with additional chips stored on the ground. The mill, at the time, operated two eight-hour shifts a day, five days a week.
Native forest controversy
The native forest woodchip industry attracted opposition from organisations including the Campaign to Save Native Forests and the South-West Forests Defence Foundation. The dispute concerned the harvesting of native forests and the use of their timber for export chips.
In July 1976, Michael Haabjoern and John Chester bombed the woodchip terminal at Bunbury with gelignite. They kidnapped a security guard at gunpoint and destroyed a conveyor tower. Two other charges failed to explode and were defused by police. Damage was reported at approximately $300,000, described by ABC in 2026 as equivalent to about $2.3 million. Despite the damage, the attack did not seriously interrupt woodchip exports.
Both men were initially sentenced to seven years’ imprisonment. The conservation movement, as a result, distanced itself from the bombing.
Aftermath of the 1976 Bunbury port bombing. (ABC Archives)
The industry underwent further environmental assessment during the 1980s. In September 1988, the State Government approved a proposal for woodchip exports of up to 750,000 tonnes a year over a further 15 years, subject to conditions.
Changes in ownership
Bunnings acquired Millars in April 1983 for approximately $25 million. The purchase covered the entire Millars business. WACAP Treefarms Pty Ltd was established in 1990 to manage WACAP’s plantation operations. Wesfarmers took full ownership of Bunnings in 1994.
In August 2000, Wesfarmers announced an agreement to sell its woodchip operations, plantation services and plantation assets to a Marubeni subsidiary for $58 million. Diamond Mill was included in the transaction, which was completed on 3 October 2000.
Marubeni established WA Plantation Resources as the holding company for the acquired business. In 2002, it sold a 40 per cent interest to Nippon Paper. Nippon Paper increased its share to 50 per cent in March 2006, giving the two companies equal ownership. In March 2013, Marubeni bought back Nippon Paper’s interest and returned to full ownership.
W.A. Chip & Pulp Co. Pty Ltd remains an active company name, with records identifying it as trading as WAPRES.
Rail transport
Rail originally connected Diamond Mill with the Bunbury export facilities. Changes in timber supply and the withdrawal of other freight users later affected the viability of the service.
Manjimup’s 2012 townsite growth plan described the Picton-Lambert railway as mothballed. It identified Diamond Mill as the last railway freight user in the Manjimup area and stated that its freight alone was insufficient to support the service. Chips are now transported to Bunbury by truck.
Diamond Chip Mill (1976)
Proposed biomass power station
A separate proposal sought to establish a 40-megawatt biomass power station at the Diamond Mill site. The plant would have burnt woody material to generate electricity. Its estimated cost was $110 million in the 2008 environmental review.
The proposal attracted objections about air emissions, truck movements and possible effects on nearby agricultural businesses. In January 2009, the Environment Minister upheld parts of the appeals and required additional conditions, including emissions monitoring.
The project remained under discussion in 2014, when an extension to its approval period was sought after a construction deadline had passed. Local food, wine and truffle producers were among those opposing it. Its prospects were discussed again in 2015 following changes to renewable energy arrangements.
Research at the mill
Diamond Mill was used for trials investigating how plantation logs dry during storage. Trials conducted in 2014 used small piles of Tasmanian blue gum and radiata pine logs.
The work examined changes in moisture content and ways of estimating drying under different weather conditions. Results were published through Forest and Wood Products Australia in 2017. The research examined whether drying logs before transport could reduce the weight of water carried and lower transport costs.
Present operations
WAPRES now describes the site as the Diamond BioHub. Its equipment includes a flail debarker, which removes bark from logs before chipping, with a stated processing capacity of up to 100 tonnes an hour. Screened chips are stored on a paved area before being trucked to Bunbury.
The business has expanded its plantation operations since the mill’s establishment. WAPRES describes its timber supply as including plantations, private forests and State timber.
Resource recovery proposal
In May 2025, the Shire of Manjimup considered a feasibility study for a resource recovery facility at the Diamond Mill site. Verge Enviro was identified as the proponent, with W.A. Chip & Pulp Co. Pty Ltd identified in the site ownership entry.
The proposal involved a private waste transfer and resource recovery facility off Eastbourne Road. Further work appeared in the council’s December 2025 agenda.
Undated WA Chip & Pulp Co Pty Ltd fliers recovered from a deceased estate before the property’s demolition.
These prompted the research for this page
WACAP’s Private Forestry Schemes
WACAP also encouraged private landowners to establish plantations through its Manjimup-based Private Forestry section. Two leaflets advertise the company’s tree seedlings and four Tree Growing Incentive Schemes.
Neither leaflet carries a publication date. Government forestry records place the introduction of WACAP’s incentive schemes in 1982. The scheme leaflet refers to Public Works Department clearing-control zones, terminology from the period before the department’s water functions passed to the Water Authority in 1985.
The four incentive schemes
The schemes were advertised for properties receiving more than 800 mm of annual rainfall. The first offered planting advice and seedlings for purchase, mainly for shade, shelter and improving the appearance of properties.
The second offered free advice and eucalypt seedlings for plantations on existing pasture. Plantings had to exceed five hectares and follow an agreed working plan. A legal agreement gave WACAP the right of first refusal over the timber, meaning it received the first opportunity to purchase the crop under the agreement’s terms.
The third covered plantations on forested sites. WACAP offered free seedlings and advice, a market for existing chipwood on the proposed planting area and double its normal lump-sum payment for private-land chipwood. This scheme provided for harvesting existing private bushland and replacing it with a commercial eucalypt plantation. Where clearing controls applied, landowners had to provide a clearing licence even though they intended to replant with trees.
The fourth involved WACAP leasing more than ten hectares, establishing the plantation and managing it. The leaflet described payment for the lease and a timber-related bonus as a lump sum at the end of the lease.
The seedling selection
The seedling leaflet lists 13 Australian species: Tasmanian blue gum, manna gum, swamp mahogany, sugar gum, Bald Island marlock, yellow stringybark, Sydney blue gum, peppermint, spotted gum, rose gum, river red gum, moort and red mahogany. The advertised uses included pulpwood, construction timber, poles, fuel, windbreaks, shade and honey production.
Several were eastern Australian species rather than WA natives. Peppermint, moort and Bald Island marlock were among the southern WA species offered. River red gum occurs naturally in parts of WA but isn’t generally indigenous to the South West.
Sugar gum, native to South Australia and widely planted for farm shelter, has escaped cultivation and is recognised as an environmental weed in parts of WA. Spotted gum appears under its former scientific name, Eucalyptus maculata, now generally accepted as Corymbia maculata. Bald Island marlock is listed as Eucalyptus conferruminata, a name published in 1980.
The leaflet gives rainfall, soil, drought, frost and dieback information, together with instructions for planting seedlings in Jiffy peat pots. These pots remain in use, although peat-free alternatives are now available. The leaflet’s brief dieback-resistance ratings do not guarantee that trees will resist infection or prevent contaminated soil from spreading the disease.
Plantations and later ownership
WACAP Treefarms Pty Ltd was established in 1990 as the plantation-management part of the business. In August 2000, Wesfarmers announced an agreement to sell its woodchip operations, plantation services and plantation assets to a Marubeni subsidiary for $58 million. A subsequent announcement records completion on 3 October 2000.
Marubeni established WA Plantation Resources, known as WAPRES, as the holding company for the acquired business. W.A. Chip & Pulp Co. Pty Ltd remains an active company name, with certification records identifying it as trading as WAPRES. The business continues to operate forestry and processing facilities in the Manjimup and Bunbury areas.
