Supplemental Information Supporting the Delisting Petition for Emerald's IWBS

Emerald Kalama Chemical's (Emerald) industrial wastewater treatment plant biological solids (IWBS) are being considered for exclusion from the designation as a Resource Conservation and Recovery Act (RCRA) hazardous waste with the condition of disposal in a Subtitle D landfill. The IWBS currently designate as hazardous because RCRA waste codes U019 and U220 remain attached to the material due to the "derived from" rule. This is despite the fact that benzene and toluene are not present at detectable concentrations in the IWBS. One element that is present in the IWBS, that has not historically been a concern, is cobalt. The EPA Delisting Risk Assessment Software has identified cobalt as a potential chemical of concern should the IWBS be placed in a Subtitle D landfill for disposal.  
Emerald has analyzed 92 samples of IWBS collected between January 2007 and March 2019. The results indicate that the concentration of cobalt in the IWBS ranges from 257 to 2,580 mg/kg and averages 768 mg/kg (dry weight). Of the 92 samples, 75 had concentrations less than 1,000 mg/kg. TCLP analyses of the four samples collected in 2019 have returned an average cobalt concentration of 1.06 mg/L. Emerald had fish bioassays performed on the IWBS in 2000 and 2014. The percent mortality of the rainbow trout was zero for both tests. Therefore, the IWBS does not meet the dangerous waste toxicity criteria referenced in WAC 173-303-100. 
Industrial biosolids are subject to regulatory limitations that municipal biosolids are not. Cobalt is not a RCRA-listed metal, nor is it included as a pollutant in 40 CFR 503.13 (Standards for the Use or Disposal of Sewage Sludge  -  Land Application). As shown in Table 1, Emerald's IWBS meet the EPA criteria for Exceptional Quality biosolids as the analytical results have shown that the metal concentrations in the IWBS are well below the limits established in 40 CFR 503.13. Only the presence of the U019 and U220 RCRA waste codes and the fact that the source of the IWBS is industrial, currently preclude the material from land application in a manner analogous to municipal biosolids.
                Table 1. Ceiling Concentrations (40 CFR 503.13)
                                  Pollutant 
                                   ppm (dry)
                                    Arsenic
                                    Cadmium
                                    Copper
                                     Lead
                                    Mercury
                                  Molybdenum
                                    Nickel
                                   Selenium
                                     Zinc
                                 Chromium [1]
                      Biosolids Pollutant Ceiling Limits
                                      75
                                      85
                                     4300
                                      840
                                      57
                                      75
                                      420
                                      100
                                     7500
                                     3000
            Exceptional Quality Biosolids Pollutant Ceiling Limits
                                      41
                                      39
                                     1500
                                      300
                                      17
                                      - 
                                      420
                                      36
                                     2800
                                     1200
                          IWBS Average Concentration
                                     4.56
                                     0.68
                                      549
                                      ND
                                     0.05
                                     5.73
                                     134.8
                                      ND
                                      633
                                     14.3
                          IWBS Minimum Concentration
                                      ND
                                      ND
                                      200
                                      ND
                                      ND
                                      ND
                                     48.6
                                      ND
                                      210
                                      ND
                          IWBS Maximum Concentration
                                     7.10
                                     0.72
                                     1600
                                     4.00
                                     0.17
                                     11.20
                                      415
                                     3.00
                                     1240
                                     22.9

(1) Chromium was listed in the 1994 "Plain English Guide to the EPA Part 503 Biosolids Rule." It is not listed as a pollutant tables 1, 2, or 3 in the current 40 CFR 503.13 regulations.
A landfill regulated under Subtitle D is the appropriate disposal location for the IWBS. Subtitle D landfills are used for the disposal of many waste streams including municipal solid waste, industrial waste, and coal ash. The IWBS poses less risk to the environment than these three waste streams. The Targeted National Sewage Sludge Survey Sampling and Analysis Technical Report (EPA 2009) indicates that the concentrations of cobalt found in municipal biosolids that are currently land applied throughout the United States ranges from 0.87 to 290 mg/kg (dry weight). Precluding the delisting of the IWBS and subsequent disposal in a Subtitle D landfill would not be consistent with the allowed land application of municipal biosolids. 
There are no limitations on cobalt that prohibit materials containing it from disposal in a Subtitle D landfill. Were it not for the RCRA waste codes for benzene and toluene, which remain attached to the IWBS, and despite the fact that the concentrations of these compounds are below detection limits, the IWBS would be accepted for disposal in a Subtitle D landfill regardless of the presence of cobalt, at any concentration. The IWBS was land applied to provide nutrients to crops for 19 years with no adverse environmental effects. Delisting and disposal of the IWBS in a Subtitle D landfill is appropriate considering the precautions taken to protect the environment from the materials disposed of in a Subtitle D landfill, the nature of the materials currently approved for disposal in them, the history of safe land application of the IWBS, and the well characterized chemistry of the IWBS.
