Table 2 Descriptions of land application tasks.
Task | Task definition | Workers’ description |
|---|---|---|
Hauling | Workers picked the biosolids up from the WWTP using a dump truck (dewatered) or an enclosed tanker (liquid). Workers drove the biosolids to the application site where they dumped the biosolids in a loading zone/stockpile (dewatered) or loaded them directly into injection spreaders (liquid). | (Liquid biosolids) “We take it in semi-trucks with tankers and there is an injector that suctions out the product and inject it into the land.” – Applicator 2 (Dewatered biosolids) “It gets dewatered and loaded into bins and then I go there, and I swap out the bins… I pull the loaded one out and put an empty one in and then I take the loaded bin and I drive that to the biosolids application storage facility where I dump it out and then it’s applied immediately or after some period of time.” – Applicator 1 |
Loading | Workers took the biosolids from the loading zone/stockpile into the spreading equipment using a pay loader (dewatered) or attached tubes to a hatch on a tanker (liquid) and suctioned the liquid biosolids out of the tanker into the spreader. | (Liquid biosolids) “Our tanks have vacuum pumps on them, so they’ll create a vacuum and suck the material off of the trailer into the spreader.” – Manager 1 (Dewatered biosolids) “The truck unloads the biosolids in a pile on the field… then the big front-end loader picks up the biosolids and loads the biosolids into the spreader and then the spreaders go.” – Manager 2 |
Spreading | Workers applied the biosolids on the field using a manure spreader, vertical or horizontal beater (dewatered), or an injection spreader (liquid) | (Liquid biosolids) “The injector looks like it creates little ditches before the product comes out the back and then once the product comes out the back there’s another pair of disks that bury it back up.” – Applicator 11 (Dewatered biosolids)“I get in a tractor that’s hooked to it [the spreader] and pull it behind across the field and engage the PTO [power takeoff] and you got these things that spin on the side, and you open a door and the sludge starts sliding out and it hits them hammers and shoots it out in the field, sprinkles it out. I just drive around in a tractor and punch buttons.” – Applicator 4 |
Post-application field work | Workers applied potash, planted crops, harvested, or did other agricultural tasks using large machinery at the biosolids land application site. | “Once it’s done, I let the farmer know ‘thank you very much that field is done so it’s yours and then if he wants to do more tillage or spread potash he can.” – Manager 2 “You could sit in a combine, you know 14, 16 hours a day and just sit there and harvest.” – Applicator 8 |
Cleaning | Workers cleaned biosolids from land application equipment, roads, and public spaces using sticks or rakes, hoses, power-washers, or shovels. | “You got these long scrapers that we use to knock it [biosolids] off the spreader and get in all them spots so we’re not actually grabbing and holding it.” - Applicator 3 “We hose it out, use a fire hose or something to basically turn it back to liquid and let it run out.” – Manager 2 |
Maintenance | Workers performed routine maintenance (including general upkeep such as greasing equipment, changing oil, or changing cab filters) and breakage maintenance (including fixing or adjusting equipment after a breakage occurs in the field). | “I show up and if I was going to do applications today, you would go grease your machines, you make sure everything’s good, the oil’s good, the tires are good.” – Applicator 5 “If [the spreader chains] bust, you have to go back there an put new links in them to get your spreader right because if one chain breaks the whole spreader won’t work.” – Applicator 3 |
