Composting Tables

Table 1
Appropriate Leaf and Grass Clippings Composting Technology

Level of Technology	Capacity^a (yd3/acre)	Buffer (feet)	Time (months)	Relative Cost	Use for Grass Clippings^c
Minimal	4000	1000*	36-60	very low	no
Low	3500	50/150/250**	16-18	low	no
Intermediate	3000^b	50/150/250**	4-6	low-moderate	perhaps^d
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.

Back to Table of Contents

Table 1 Appropriate Leaf and Grass Clippings Composting Technology

Table 1
Appropriate Leaf and Grass Clippings Composting Technology