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Explore the regulatory issues and environmental impact of disposing CCA-treated wood in Florida, including leaching characteristics, soil contamination, and combustion emissions.
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Florida CCA Regulatory Issues Bill Hinkley, Chief, Bureau of Solid and Hazardous Waste Satish Kastury, Administrator, Hazardous Waste Regulation Section Richard Tedder, Administrator, Solid Waste Management Section
Amount of CCA-Treated Wood To Be Discarded Estimated from a Mass Balance Model Service Life 25 yrs L&T 40 yrs Poles CCA Production Disposal AWPI/AWPA Statistics & SFPA Projections
Cumulative Quantities Before Ban
Cumulative Quantities With Ban
590 Lake Okeechobee’s Equivalent to 4.83 x 1012 L water at 10 ug/L 100 yds x 50 yds x 63 ft of granulated As2O5 Amount of ArsenicTo Be Discarded • Cumulative Amount of As Imported = 31,400 tons • Cumulative Amount of As Disposed to Date = 2,250 tons • As in “In-Service” Wood= 29,150 tons Statistics for the Year 2002 (Florida)
216,000 miles of 2 x 4’s 9 times around 100 yds x 50 yds x 2.7 miles Amount of CCA-Treated Wood To Be Discarded Statistics for the Year 2002 (Florida) • Cumulative Volume Imported = 635 million cubic feet • Cumulative Volume Disposed = 45 million cubic feet (7%) • Volume in Service = 590 million cubic feet
Leaching Characteristics of CCA-Treated Wood • TCLP used to characterize solid wastes as hazardous waste • As TC concentration = 5 mg/l • Currently exempt from definition of hazardous waste
Typical TCLP Results(New Wood) TC for As and Cr(5 mg/l) Results Based on Two Pieces of 0.25 pcf CCA-C Dimensional Lumber
Typical TCLP and SPLP Results(New Wood) TC for As(5 mg/l) Results Based on Two Pieces of 0.25 pcf CCA-C Dimensional Lumber
Mulch Leaching Data Future GWCTL for As?
Future TCLP Limit? Ash Leaching Data
Regulatory Concerns Based on the research of Solo-Gabriele, Townsend, Ma and others, there are regulatory concerns about CCA treated wood in four areas: • In service impacts • Reuse • Combustion • Land Disposal
IN SERVICE IMPACTS-SAWDUST • CCA treated wood sawdust routinely fails TCLP • However CCA wood, used for its intended purpose is exempt from RCRA. • Does the exemption cover sawdust? • If sawdust is not exempted, who is regulated, and how? • Furniture and other wood product manufacturers • Building supply stores that cut wood for customers • Contractors building decks at residences
IN SERVICE IMPACTS-SOIL CONTAMINATION • CCA treated wood decks and boardwalks are causing arsenic contamination in the underlying soils • The average As soil concentration found under Florida decks was 29 mg/kg • This is well above the RCRA arsenic soil screening value and the state’s clean soil criteria: • RCRA Soil Screening value: 0.4 mg/kg • Florida cleanup/residential: 0.8 mg/kg • Florida cleanup/industrial: 3.7 mg/kg • Florida cleanup/ leaching: 27.5 mg/kg
IN SERVICE IMPACTS-SOIL CONTAMINATION • Note that the soil leaching value is based on an MCL of 50 ug/l. EPA has recently announced its intention to lower the MCL to 10 ug/l. This would lower the SCTL Leachable value to 27.5/5 or 5.5 mg/kg • There are an estimated 30,000 acres of CCA treated wood decks and boardwalks in Florida. • What regulatory criteria, if any, apply to this situation?
REUSE-MULCH • Construction and demolition debris wood is frequently ground up, dyed and sold as a decorative landscaping mulch. This wood can contain CCA treated wood. • As little as 1% CCA treated wood in mulch will cause it to leach arsenic in excess of the current MCL of 50 ug/l.
REUSE-MULCH (con’d) • It is not lawful under current Florida regulations for permitted solid waste management facilities to make mulch from CCA treated wood. • But weathered CCA wood is difficult to distinguish from non-treated wood. Also, some manufacturers of mulch are not regulated as solid waste facilities.
COMBUSTION—EMISSIONS • Preliminary mass balance evaluation of CCA treated wood burned in industrial boilers suggests that a significant fraction of the arsenic in the wood cannot be accounted for in the ash and apparently escapes as both particulate and gaseous (arsine) emissions.
COMBUSTION—EMISSIONS (con’d) • What kinds of air pollution control equipment are needed to control arsenic emissions? • More research and analysis is needed, especially since burning CCA wood under controlled conditions—i.e. in a waste-to-energy plant or dedicated industrial boiler-- may be best long-term disposal strategy.
COMBUSTION—ASH • Ash from the combustion of CCA treated wood contains thousands of parts per million of arsenic, is highly toxic and fails TCLP. • However, ash from combustion of a wood mixture with as little as 6% CCA treated wood will also fail TCLP. • The average amount of CCA treated wood in the Florida wood waste stream is also currently about 6%, but will rise to 25-30% over the coming decades).
LAND DISPOSAL • Both laboratory and field data indicate that CCA treated wood disposed of in landfills leaches arsenic well above the proposed new arsenic MCL of 10 ug/l. • Generally, in Florida, construction and demolition debris is disposed of in unlined landfills, since C&D debris is “inert” and “non-polluting”.
LAND DISPOSAL (con’d) • Florida is currently evaluating whether CCA treated wood should be banned from unlined landfills, or whether C&D disposal sites should be lined. • Such changes make sense but there are significant repercussions which have to be considered, such as closure of many sites, soaring disposal fees and increased illegal dumping.