Napa Co-composting CASP Report
Citation: Earth Foundries, Inc. (2023). Final report: Co-composting biochar at Napa Recycling in an upflow covered aerated static pile (CASP) engineered composting system. 23 August 2023. https://www.earthfoundriesinc.com/wp-content/uploads/2024/02/Earth-Foundries-Green-Compost-Biochar-Composting-Project-Report-2023.pdf
What it is: A commercial-scale demonstration at Napa Recycling’s covered aerated static pile system, comparing one pile of green and food waste with biochar against one control pile. The vault uses it for composting-process benefits.
Key figures
| Figure | Value | Where | Check |
|---|---|---|---|
| Setting | Napa Recycling, American Canyon, CA; 12 June–2 August 2023; one biochar pile vs one control pile over one composting cycle | Report PDF, summary | ✓ full text |
| Biochar loading | 10% by volume of forestry-residue biochar, mixed into green and food waste | Report PDF, summary | ✓ full text |
| VOC emissions | Non-methane VOCs −33% across the composting cycle (255 measurements, using “R-25”, a simplified EPA Method 25.3) | Report PDF, summary and methods | ✓ full text |
| Maturity | Low free ammonium reached one week sooner than the control | Report PDF, summary | ✓ full text |
| Finished compost nutrients | NPK value +11% vs the control | Report PDF, summary | ✓ full text |
| Finished compost salinity | Calcium and magnesium salts down by more than half | Report PDF, summary | ✓ full text |
| Test length | 51 days: 35 in the aerated bunker, 16 curing | Report PDF, methods | ✓ full text |
Use with care
- Correction to earlier vault notes: the loading was 10% by volume, not by weight.
- One pile per treatment over one cycle, with no replication. Treat it as a facility demonstration.
- These are composting-process results, not field soil or N₂O results (GHG Fluxes).
Related: Biochar Compost and Manure Blends · Real World Soil Projects · Key Sources