26 Tinus and LaMana: Conversion Efficiency and Economics of Urban Wood Utilization logs either on an owner’s property, from company land holdings, or ‘at the gate.’ Because the study logs were never owned by a wood processing company, customers instead paid separate fees for transport and processing of their logs into primary wood prod- ucts, such as rough sawn boards. Customers were charged a per km (per loaded mile) transport fee from the customer’s job site to the mill site in Dauphin County, Pennsylvania, in addition to a milling fee of USD $0.18 per “board-foot,” based on the esti- mated board-footage (or metric volume) of their logs. Generally, every log in this study would have likely gone into a dumpster or chip truck for disposal into a landfill, absent the treatment in this study. This is because the clients (job sites) were self-selected and were choosing this form of recycling rather than landfill disposal. While the processor owns the only sawmill used to process study logs, labor for sawmill operations is subcontracted under this operating structure. Contracted sawyers were paid a flat fee for each board foot unit of rough sawn lumber produced regard- less of species, dimension, or grade. During the study period, from January 2007 through March 2008, 21 separate job sites in five states and one territory (MD, NJ, NY, PA, VA, and D.C.) were self-identified by customers to the company. These 21 job sites represent every suburban and urban log recovery operation undertaken by this company in the geographic study area during the study period. The number of harvested logs at each of these job sites ranged from 1 to 29 and was comprised of hardwood, conif- erous, and deciduous softwood species. Logs from each job site were treated and held separately at all stages of the study. Once at the mill site, each log was graded (Rast et al. 1973), and log diam- eters at each end, log length, and species were recorded. Prior to milling, the potential recoverable volume of each study log was scaled using the “international 1/4 inch Log Rule” (NHLA 2007). All logs were visually inspected for signs of metal or other contamination prior to milling and then scanned with a White’s weight landfill disposal rate, Rh is the hauling rate per mile, and fs Date + Rdw = cost of disposal, and Rh Location 1/20/2007 2/6/2007 2/15/07 2/27/2007 3/4/2007 3/27/2007 4/27/2007 5/4/2007 5/10/2007 5/16/2007 7/2/2007 1/8/2008 1/10/2008 1/11/2008 1/14/2008 1/16/2008 1/17/2008 1/18/2008 1/18/2008 1/30/2008 2/27/2008 Means (SD) Clewiston, NJ Takoma Park, MD Washington, DC Arlington, VA Westchester, PA Arlington, VA Horseshoe Road, PA Midland park, NJ Bronx, NY Midland Park, NJ Summit, NJ Blairstown, NJ Swarthmore, PA Westchester, PA Summit, NJ Perkasie, PA Vestal, NY Pompton Plains, NJ Glen Garden, NJ McLean, VA High Bridge, NJ + fs Cost of disposalz 1025 400 400 400 400 775 400 1800 400 1550 400 900 1150 1675 400 1675 525 1025 525 1675 925 877 (520) Classic IV Metal detector for remaining metallic contaminants. Additionally, during the milling process, all exposed faces were visually re-inspected and re-scanned for contaminants likely to be encountered in the next cut. Where metal contamination was en- countered, those log sections were excised, measured and recorded, and the remaining sound log sections were re-scanned and milled. All study logs were milled into green, rough-sawn, 4/4” (approximately 2.7 cm) lumber of various lengths using a small diesel-powered sawmill (Mighty-Mite Circular Mill, Model D- 812H). Rough-sawn green boards were then evaluated for quality and defects and assigned as No. 1, No. 2, or No. 3 Common, according to published standards for hardwood lumber grading (NHLA 2007). The volume of slabs, cull sections, and sawdust was determined by subtracting the observed lumber recovery from the estimated log volume. The LRF was determined by dividing the observed lumber volume by the scaled lumber volume. For logs obtained from each job site, the value of avoided disposal was calculated by estimating green weight by species (USDA FS Wood Handbook 1987) and material volume, multi- plied by an average local landfill (municipal disposal area) fee. These value estimates were compared with the cost of trans- port to the mill site to yield the value of avoided disposal at each job site (Table 1). The difference in cost between landfill disposals versus hauling to the study mill for value-added pro- cessing was described by the following generalized equation: [1] {Rdv(2.2Vl ) + Rdw (Wl )} – {Ml disposal rate (USD$/m3), Rdw correction factor for the average air gap when the material is con- tainerized, Wl where Vl = total log volume (m3 = total log weight t (tonnes), Rdv ($/t over base-t/load), Ml = loaded distance to mill (km), Rh = hauling cost; where Rdv is the fuel surcharge. Currency is represented in U.S. dollars. Mileage is the volumetric landfill disposal rate, Rdw Hauling costy to mill 173 176 184 306 150 306 71 229 236 229 206 166 93 140 83 159 175 100 80 165 174 171 (66) z Cost of disposal assuming $400/40yd. container rounded up to 40yd. units, $125/ton over seven tons. y CitiLog charge per loaded mile, including fuel surcharge (subject to change) was $4.91. x Price differential = (avoided disposal - realized hauling cost). ©2013 International Society of Arboriculture 849 864 903 1502 737 1502 349 1124 1159 1124 1011 815 457 687 408 781 859 491 393 810 854 842 (325) Price differentialx 176 -464 -503 -1102 -337 -727 51 676 -759 426 -611 85 693 988 -8 894 -334 534 132 865 71 35 (606) (Rh + fs )} = Cr ) and 2.2 is an empirically derived = volumetric landfill = overweight landfill disposal rate = haul- Table 1. Job sites, locations, and dates showing the avoided cost of disposal and hauling cost to the mill for each job. In equa- tion [1], Rdv is the over-
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