The group against the facility raised concerns about its odour and the affect on nearby properties from runoff into waterways and vectors eating the biosolids.

However, Conhur director Dean Hurlstone, who will develop the site, claims there are no health risks, no runoff possibilities and the risk of odour affecting nearby properties was low.

He said the facility was designed so no offsite impacts were expected to occur.

"Odour modelling suggests that the likelihood that nearest neighbours will detect odour is very low with worst case assumptions. If offsite impacts occur the operator may not be allowed to continue operating," he said.

A development application for the 91 Blessington Road site was re-listed for public comment, after it was taken down due to clerical errors in May.

Initially it will process between 3000 to 5000 tonnes of biosolids annually from TasWater's northern sewerage treatment plants.

It will improve it from class three, which if untreated must be sent to landfill, to class two through a compost technique. The resulting compost will be spread over 194 hectares of the site.

However, in future the composted biosolids may be transported to other properties.

The process involves mixing the biosolids with wood chips and forming it into long piles on a 2.1 hectare clay pad to aerate it periodically over 12 weeks by turning the piles to reduce contamination. The piles will be sampled for contamination levels.

Biosolids are produced from the treatment of sewage, after the water is cleaned and discharged, it's the remaining solid sludge from toilets, sinks, dishwashers, washing machines and showers.

The proposed facility is located near three waterways - Distillery Creek, St Patricks River and the North Esk River. A group spokesperson said at least 19 nearby households drank directly out of those waterways, before it's treated, raising concerns about their future water quality.

They said the compost piles should be processed undercover to prevent odour, vectors and runoff, similar to what Dulverton Waste Management is constructing.

"No where in the DA does it mention vectors ... what happens if the birds go and feed on it," they said.

Mr Hurlstone said Conhur had been involved in Australia's reuse of biosolids for more than 15 years and there were no health risks for nearby residents.

"No runoff from the composting facility can enter a waterway. All water from the pad is collected in a leachate dam and recycled into windrows or irrigated in an approved area if necessary," he said.

"There are buffer distances specified to waterways, roads, houses, as well as limitations on slopes and other parameters. These control methods have proven to be effective at preventing the movement of applied biosolids from target areas."

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Two testing areas of the site, under one of the identified pivots, found cadmium levels were naturally above the maximum allowed soil contaminant concentration level and would not be suitable for biosolid spreading.

This is because biosolids contain a range of pathogens, nutrients and metals, therefore even after composting it can not be applied to sites where the existing contaminant concentrations exceed the maximum allowed.

The group's spokesperson said industry standard meant re-testing should be done to see if it exceeded the maximum cadmium levels on other testing sites.

So far 194 hectares have been tested and approved for spreading, with further testing to see the viability of an additional 1386 hectares.

The group were concerned the expansion of spreading areas would happen without notification.

"They are the processor and the end user, they will be self regulating," they said.

"It's a ticking time bomb."

The DA is open for public comment on the City of Launceston council's website until July 27.