Key Takeaways from the Article:
- Comparison of Common Debris Disposal Methods – A breakdown of hauling, grinding, and burning, including cost implications and efficiency.
- Volume Changes from Grinding – How logs expand while branches shrink, affecting final material volume.
- Burning as the Most Efficient Disposal Method – Reducing debris volume by 90-95%, making it the most cost-effective option.
- Cost & Time Analysis for Large-Scale Debris Disposal – Estimated volume reductions and costs for handling 50,000 cubic yards of tree debris.
- Practical Recommendations for Cost Control – Choosing the best disposal method based on project goals, environmental regulations, and logistical considerations.
Understanding Debris Management Costs
To effectively reduce the costs of waste management and disposal, it’s essential to understand the factors that influence the final volume of debris you need to handle. Below, we examine the key variables that determine both the time required for disposal and the associated costs.Common Debris Disposal Options
- Hauling – Loading debris into trucks and hauling it away.
- Grinding – Processing material into mulch of varying sizes.
- Burning – Using an industrial incinerator or air curtain burner.
- Volume increase for grinding logs
- Logs are dense, and grinding them introduces air space, initially increasing volume by about 20-50%.
- Assumption: 1,000 cubic yards of logs will expand by 30% (midpoint estimate).
- Final volume from logs:1,000×1.3=1,300 cubic yards1,000×1.3=1,300 cubic yards
- Volume reduction for grinding branches and limbs
- Branches contain significant air space, so grinding them reduces volume by about 75-80%.
- Assumption: 1,000 cubic yards of branches will be reduced by 77.5% (midpoint between 75% and 80%).
- Final volume from branches:1,000×(1−0.775)=225 cubic yards1,000×(1−0.775)=225 cubic yards
Final Volume of Ground Material:
If you start with 1,000 cubic yards of 20″ diameter logs and 1,000 cubic yards of branches, you will end up with approximately 1,525 cubic yards of finished ground material after processing. This is a reduction of only 475 cubic yards compared to the original 2000 cubic yards of debris.What Happens When You Burn the Same Amount of Material?
Burning tree debris using an air curtain burner, incinerator, or open burning significantly reduces volume compared to grinding or hauling. The main benefits and effects include:Volume Reduction Efficiency
- Burning achieves the highest volume reduction of all methods.
- Typically, 90-95% of the original volume is reduced to ash.
- Example Calculation: If you start with 2,000 cubic yards of mixed debris (logs + branches), after burning, you will be left with only 100-200 cubic yards of ash.
Scenario: Disposing of 50,000 Cubic Yards of Tree Debris
If you start with 50,000 cubic yards of mixed tree debris (logs + branches), the final volume after processing will depend on the disposal method chosen.Option 1: Hauling (Most Expensive)
- No volume reduction – The entire 50,000 cubic yards must be transported.
- This is the costliest and most time-consuming option due to transportation and landfill fees.
Option 2: Grinding (Moderate Cost Reduction)
- Branches & Limbs: Reduce volume by 75-80%.
- Logs: Initially expand in volume by 20-50% before settling.
- Estimated Final Volume: ~38,125 cubic yards of ground material.
- Requires storage, transportation, or repurposing (e.g., mulch, biomass fuel).
Option 3: Burning (Most Cost-Effective)
- Burning reduces volume by 90-95%, leaving only ash.
- Final volume: 2,500 to 5,000 cubic yards of ash.
- Fastest method for disposal, but subject to local air quality regulations.
Summary of Volume Outcomes
| Disposal Method | Initial Volume | Final Volume | Estimated Reduction |
| Hauling | 50,000 CY | 50,000 CY | 0% |
| Grinding | 50,000 CY | ~38,125 CY | ~24% |
| Burning | 50,000 CY | 2,500-5,000 CY | 90-95% |
Conclusion
- Burning is the most efficient method, reducing debris to a fraction of its original size.
- Grinding provides some reduction but still results in significant material to manage.
- Hauling is the least efficient and most expensive option for debris management.
The Effects of Adding Water to Ash:
When you wet down ash, its volume will decrease due to compaction, but the exact reduction depends on several factors, including the amount of water added, the ash’s composition, and how much it settles. Here’s what happens:
Compaction & Volume Reduction
-
-
- Dry ash is light and fluffy, with significant air pockets.
- Adding water causes the ash particles to bind together and settle, reducing air space.
- Estimated Reduction: Volume can decrease by 20-50%, depending on saturation levels.
-
Increased Weight
- While volume decreases, weight increases significantly.
- Wet ash is much heavier than dry ash, making transportation and disposal more challenging.
Potential for Hardening
- If wetted excessively, ash can harden and form a crust, especially if it contains mineral content like calcium or silica (similar to cement behavior).
- This can reduce dust, but it may also create disposal or spreading difficulties.
Example: 5,000 Cubic Yards of Ash
- Minimal Water Added (Light Moistening) → Volume Reduction: 10-20% → Final Volume: 4,000 to 4,500 CY
- Moderate Water (Fully Saturated but Not Pooling) → Volume Reduction: 20-30% → Final Volume: 3,500 to 4,000 CY
- Excessive Water (Heavily Saturated, Mud-Like) → Volume Reduction: 30-50% → Final Volume: 2,500 to 3,500 CY
Final Takeaway:
- Adding water will significantly reduce ash volume (by 20-50%) due to compaction.
- The more water added, the more the volume shrinks, but the weight increases.
- Excess water can cause hardening, making it difficult to spread or dispose of.
If you’re considering wetting ash for dust control or compaction, you may want to test a small section first to determine the ideal moisture level for your needs.