Dewatering vs full material recovery
Two ways a receiving facility can handle hydrovac slurry. Both take the water out. They differ in what happens to everything else, and that difference shows up in reuse options, water use and the records you get.
| Dewatering | Full material recovery | |
|---|---|---|
| What comes out | Water and one mixed solid | Stone, sand and clay as separate materials, plus treated water |
| Reuse options for the solids | Reuse as dry soil where the batch meets the requirements and a site can accept it | Each material matched to applications that suit it, such as backfill, bedding or fill |
| The water | Varies by facility: discharged, disposed of or reused | Treated and reused in the process and to refill trucks |
| Landfill restriction from 2027 | Mixed solids that can't be placed for reuse still need somewhere to go | More of each load has a reuse route, so less depends on landfill |
| What you can report | That the load was received | That the load was received and separated for recovery |
What dewatering does well
Dewatering is a legitimate step, and Ontario's guidance recognises it.
Taking the water out of liquid soil, by settling, pressing or adding a solidifying agent, turns it into something that can be handled like dry soil. Ontario's excess soil guidance names de-watering or solidifying as a way to make liquid soil reusable as dry soil. Where that dried material meets the quality standards for a reuse site, it can go back into the ground.
The limit is that it stays one mixed material. Its uses are the uses of that particular mix, and when a batch doesn't suit any available site it's headed for disposal.
What full recovery adds
Full recovery keeps going after the water comes out. The solids are separated by size in stages, washed, and stockpiled as stone, sand and clay. Those are materials with established uses in construction, and each can be matched to work it suits.
The water gets the same treatment. Rather than leaving the site as a by-product, it's treated and reused, including in the trucks that brought it in.
Why it matters under 406/19
Ontario Regulation 406/19 treats hydrovac slurry as liquid soil and sets rules for where excess soil can go. Liquid soil can only be placed at a reuse site when a site-specific instrument allows it, and from January 1, 2027 cleaner excess soil is restricted from being landfilled.
Both points push in the same direction: toward receiving facilities that can turn liquid soil into material with somewhere useful to go. Our plain-language guide to 406/19 covers the details.
Questions to ask any receiving facility
Whoever you tip with, these are fair questions. A good facility answers them without hesitation.
- What's your approval number? Any Ontario facility receiving liquid soil should be able to tell you which approval it operates under.
- What do you accept, and what don't you? Clear acceptance rules protect you from a load being refused or mismanaged.
- What happens to the solids after the water comes out? This is the question that separates dewatering from recovery.
- What happens to the water? Reused, discharged or disposed of.
- What records do I get for my load? Useful for your own compliance files and any diversion reporting.
Common questions
Is dewatered hydrovac slurry always sent to landfill?
No. Ontario recognises dewatering or solidifying liquid soil so it can be reused as dry soil. Whether a given batch is reused depends on its quality and on finding a site that can accept it.
What does full material recovery add?
Separation into distinct materials. Instead of one mixed dry soil, the load becomes stone, sand, clay and treated water, each of which suits different applications.
How can I tell which kind of facility I'm using?
Ask what happens to the solids after dewatering, what happens to the water, and what records you get. A recovery facility can describe each output stream.