Table 1
Appropriate Leaf and Grass Clippings Composting Technology

Level of Technology Capacitya
Use for Grass Clippingsc
Minimal 4000 1000* 36-60 very low no
Low 3500 50/150/250** 16-18 low no
Intermediate 3000b 50/150/250** 4-6 low-moderate perhapsd
High 6000 50*** 3-4 moderate perhaps

aBased on fall collection of leaves in one year.
bAssumes 5 foot pile height, 10 foot width, and 10 foot aisles.
* From operations to sensitive neighboring land uses.
** From operations to: property line/sensitive neighboring land uses/place of human occupancy.
*** From operations to property line for totally enclosed system with odor control; otherwise, same as for intermediate.
cWith additional requirements.

dBuffer zone of 1000 feet from staging and grass clipping handling areas to sensitive neighboring land uses.

Table 2

Generalized Schedule, and Equipment and Manpower Requirements for a
Moderate Sized (15,000 cubic yard) Low Level Technology
Leaf Composting Operation
Operation Months Flexibility Front Loader(days) Laborer(days)
Prepare site Sep.-Oct. Yes 2 2
Form windrows Nov.-Dec. No 30 30
Combine windrows Dec.-Jan. Yes 10 --
Turn windrows Mar.-Apr. Yes 5 --
Additional turnings May-Aug. Yes 5 each --
Form curing piles Aug.-Sep. Yes 5 --
Shredding/screening Mar.-May Yes 20 20

General assumptions and notes:
(1) site has been prepared to allow all necessary truck access and loader operation under any expected weather conditions;
(2) leaves delivered in bulk or in paper bags (no plastic bags);
(3) adequate supply of water on site (average of 20 gallons water per cubic yard of leaves);
(4) daily supervision during periods of activity and regular checks at other times also needed;
(5) distribution of finished compost not included;
(6) other equipment, such as a grader, may be required;
(7) windrow size 6 feet high by 12-14 feet wide (avoid compaction);

(8) aisles 1-2 feet for pairs of windrows, 12-16 feet between pairs.

Table 3
Problems Encountered at Leaf and Yard Trimmings Composting Sites
Problem Cause Recommendation
Odor Piles too large - Initial windrows should be no larger than 6 feet high by 14 feet wide.
Leaf storage

- Allow no more than 1-2 days between collection and windrow formation.
Leachate ponding - Eliminate ponding.
- Add lime.*
Plastic bags - Do not accept plastic bags at the site.
Grass clippings

- Do not accept grass clippings at the site.
- Immediately incorporate into leaf windrows.
- Mix at least 3 yd3 decomposed leaves per 1 yd3 grass.
Leachate ponding Inadequate slope, poor grading - Regrade site.
Improper windrow alignment - Run windrows down slope, not across it.
Surface water pollution Leachate discharge - Treat leachate before it leaves site by passing it through soil or sand.
Ground water pollution Nitrogen leaching into groundwater - Limit grass clippings.
- Mix at least 3 yd3 decomposed leaves per 1 yd3 grass.
- Collect leachate for treatment.
Slow composting Material too dry - Add sufficient water initially, or as corrective measure during turning.
Acid anaerobic (piles too large) - Make piles smaller, adding lime* if needed to raise pH and control odors.
Illegal dumping Uncontrolled access - Limit access to site (gate).

* Pulverized limestone, dry or as water slurry.

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