Waste Management are contracted by Hamilton City Council to remove biosolids from its wastewater treatment facility in Pukete. This was being done using hook bins, a method which required a number of small bins to be rotated and transported to landfill.
When it became necessary to improve the efficiency of this process, the HCC site team liaised with Regal. We suggested a two-stage solution process which would maximise productivity, limit the number of staff on site, and meet all health and safety regulations.
The wastewater treatment facility had been designed to discharge waste through a number of chutes, filling multiple bins. These bins were small in size and needed to be replaced frequently. This was a complicated solution to what should have been a simple process.
By thinking about the problem from a ‘bulk’ perspective, Regal was able to simplify the situation, resulting in efficiency gains for all parties involved. This was done in two stages.
The first involved two truck and trailer units; the second, the construction of a concrete block walled bin and a small wheel loader.
As the plant runs 24/7, there was a requirement for there to always be a unit parked under the discharge chutes as the flow of product was continuous"
Peter Muir, Sales and Marketing Manager for Regal Group, says the initial solution required the use of two trucks and three trailers. One truck and trailer was parked under the various discharge hoppers on site, while the other truck transported the previously loaded unit to the landfill. A spare trailer was left on site to be filled, but this solution had its own challenges.
“As the plant runs 24/7, there was a requirement for there to always be a unit parked under the discharge chutes as the flow of product was continuous,” Peter explains. “This required detailed planning and communication between the operations staff at HCC and Regal. Errors could result in HCC having to stop their operation or units being over/under loaded. Although a good system had been developed and there was communication between all parties involved, there were obvious efficiency losses.”
That’s when Regal suggested a second solution.
“The second solution saw us install a concrete block walled bin so the biosolids could be contained and discharged through the pipe network in bulk,” explains Peter. “This bin is of a size that our driver only needs to remove it once a day, though he’s in constant communication with wastewater treatment plant if the bin needs emptying more frequently.
“We have a small wheel loader on site, which our driver uses to load the truck. This is fitted with a loadrite system, which means we can accurately load the unit to the highest legal weight, maximising the truck’s full load. This reduces the number of trips we need to make, which is a significant factor given part of the unit’s route is through a semi-residential area,” Peter says.
Regal worked closely with the HCC site team to ensure they were comfortable with the changes required to implement the walled bin, including any potential impact on water quality discharged from the site. “This was a serious condition of the site’s resource consent and is stringently monitored so it was important this wasn’t affected,” says Peter.
The construction of the walled bin also converted the previous load rate, which was one price irrespective of weight carried, to a $/tonne rate, and required some minor changes to the site in order to improve traffic flow.
“We also ensured the HCC site team were comfortable with the safety and security of night loading out. Having the one dedicated driver means he is totally familiar with all potential hazards on site and is actually seen to be part of their team” adds Peter.
The outcome of Regal’s involvement and second stage solution was a much simpler discharge operation for HCC staff. By converting the area to a large bin, monitoring of discharge was dramatically reduced and staff were no longer having to constantly watch the discharge hopper area.
Regal also takes all biosolids to a worm farm, rather than to a landfill. “This means it can be mixed with other fibre material and utilised as worm food. The worms seem to love it and the result is a vermacast full of nutrients and great for soil conditioning” Peter says.
Open communication and innovative design has meant all parties involved are happy with the outcome –including the worms.