[USCC] Mulch production costs and screening

[Craig Coker]

James:

1) The cost of grinding is a function of age of grinder, screen size in the
grinder, type of material being ground (on an easy-hard scale of 1-10:
pallets = 2; yard waste = 6-7 and fibrous palm tree material = 9), on
moisture content, and on freshness (dried and old is easy, fresh and wet
isn't).  

When I was grinding sawmill debarker waste in '01-'03 (which was an easy
grind), costs were ~ $3.50- $4.00 per CY (2002 dollars) with an old beat-up
horizontal.  A client of mine just had some accumulated stumps, etc. ground
up by a contractor with a tub - costs were ~ $6 - $7 / CY, although the job
was bid as a lump sum and the volumes of screened material were estimated.

2) The same client screened his grindings with both a 1/2" and a 1/4" screen
on a Doppstadt trommel.  The overs were kept for bulking agent for his
composting facility; the 1/4" - 1/2" material is selling as a Filtrexx
filter sock media; and the 1/4" minus is selling (as is) as a soil
conditioner.  It's too fine-grained to be of much value in composting (which
prefers a 2"-3" grind), and much of the carbon is likely to be lignin, and
thus of limited bioavailability during the composting timeframe.  Also, many
landscapers still believe you can break up a clay soil by tilling in woody
material directly into the soil (notwithstanding the drain that puts on soil
nitrogen).

I hope this helps.

Cheers,
Craig

Craig Coker
Coker Composting & Consulting
3331 Glade Creek Blvd., Ste. 7
Roanoke, VA 24012
Tel.: (540) 904-2698
Fax: (540) 904-6732
Cell: (540) 874-5168
Email: craigcoker at cox.net
Web: www.cokercompost.com
 

-----Original Message-----
From: compost-bounces at mailman.cloudnet.com
[mailto:compost-bounces at mailman.cloudnet.com] On Behalf Of Short James
(DNREC)
Sent: Monday, April 07, 2008 3:00 PM
To: compost at mailman.cloudnet.com
Subject: [USCC] Mulch production costs and screening

On the issue of mulch production from yard waste (grass clippings,
leaves, braches, brush and Xmas trees) I would like to know the
following:

 

1.	Does anyone have actual cost data to produce mulch from yard
waste via a grinder? Per cubic yard costs would be preferred but per ton
costs will work as well. 
2.	Does anyone have any experience with screening the ground mulch
to remove the fines and using the fines to produce compost? 

 

Any info you can provide would be appreciated.

 

Thank you. 

 

James D. Short

Environmental Scientist IV

Solid and Hazardous Waste Management Branch

Phone: 302-739-9403

Fax: 302-739-5060

Email : james.short at state.de.us

 

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