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Ohinemuri Regional History Journal 46, September 2002

The Tirohia Quarry, located on Quarry Road off State Highway 26, some seven kilometres south of Paeroa, started operations in the early 1930s. A family owned company headed by Harry Leach, H.G.Leach & Co.Ltd, purchased the quarry in 1952. The quarry extracts about 70,000 cubic metres of rock a year.

General Manager, Eric Souchon, commenced work with H.G. Leach& Co.Ltd in 1996 and he first started thinking about creating a landfill where all of the andesite rock had been removed, in November of that year. He presented his idea to the Board and eleven months later the Company made their plans public. In March 1998 the Company lodged resource consents with the Hauraki District Council and Environment Waikato. Work started three years later, following two Court appeals. Millions of dollars were spent obtaining planning and resource consents and in building the facility.

On 13 October 2001 an Open Day, organised by the owners, H.G. Leach & Co. Ltd, in conjunction with the Paeroa Rotary Club and the Tirohia School was held to enable the public to inspect the Tirohia Landfill site before it started taking waste, the culmination of five years of planning. Money raised from the Open Day went to the Tirohia School and the Life Education Trust. Two buses were used to ferry people from the car park area up to the landfill site in the Tirohia Quarry. Landfill staff lead the tours and were available to answer queries and each visitor was given a brochure providing a map and essential information. Excavators, dump trucks and other quarry vehicles were on show.

The Tirohia Landfill is the first modern landfill to be created in the region. Waste is expected from the Matamata-Piako and Hauraki Districts, some parts of the Western Bay of Plenty and from the Thames Coromandel District. A feature of the landfill is the strict environmental controls to seal the landfill base to prevent run-off seeping into ground water. The groundwater is protected by sixty metres of impervious rock, 600mls of densely packed clay and a high density polyethylene liner. Only non-hazardous waste will be accepted. Every precaution has been taken to ensure that leachate (the liquid residue from the landfill) does not get into stormwater and into the nearby stream. A conductivity monitor, connected to an alarm, checks for contamination. The leachate will be collected in fully-lined holding ponds where it will be pumped into tankers and treated off-site.

Quarry Road has been improved and a three-lane road has been created, going up the hill to the landfill.

The landfill is to be created in two main parts. The nine-stage Phase A will have a capacity of 1.2 million cubic metres of refuse and it is expected that this stage will take about twelve years to fill. Phase B, which will require additional consents under the Resource Management Act, is expected to take about 1.6 million cubic metres of waste over fifteen years.

The landfill area is expected to grow as andesite rock is removed from the site. As the landfill grows, sealed cells will be established. These will be vented and the flammable gas, created by decomposing waste, will be burned by controlled "flaring".

The Tirohia Quarry is described as an excellent place to put a landfill. H.G. Leach & Co. owns about one hundred hectares of land on which the ten hectare quarry is situated. The Company has planted a lot of trees and shelter belts on the property to minimise the visual impact of the landfill and quarry site. In all, more than 11,000 native plants have been planted on site. Pasture on the quarry land has been leased to nearby dairy farmers and earthworks around the quarry have been covered with coconut matting to prevent erosion.

H.G.Leach & Co. Ltd has committed itself to environmental monitoring of the site for a period of up to thirty years after the landfill is closed.