Table 749-3 
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Ecological Indicator Soil Concentrations (mg/kg) for Protection of Terrestrial Plants and Animalsa.  For chemicals where a value is not provided, see footnote b.

Note:  These values represent soil concentrations that are expected to be protective at any MTCA site and are provided for use in eliminating hazardous substances from further consideration under WAC 173-340-7493 (2)(a)(i).  Where these values are exceeded, various options are provided for demonstrating that the hazardous substance does not pose a threat to ecological receptors at a site, or for developing site-specific remedial standards for eliminating threats to ecological receptors.  See WAC 173-340-7493 (1)(b)(i), 173-340-7493 (2)(a)(ii) and 173-340-7493(3).

Hazardous Substanceb Plantsc Soil biotad Wildlifee


  Aluminum (soluble salts) 50       
  Arsenic III      
  Arsenic V 10  60  132 
  Barium 500     102 
  Beryllium 10       
  Boron 0.5       
  Bromine 10       
  Cadmium 20  14 
  Chromium (total) 42  42g   67
  Cobalt 20      
  Copper 100 50 217
  Fluorine 200      
  Iodine 4      
  Lead 50 500 118
  Lithium 35      
  Manganese 1,100    1,500
  Mercury, Inorganic 0.3 0.1 5.5
  Mercury, Organic       0.4
  Molybdenum 2    7
  Nickel 30 200 980
  Selenium 1 70 0.3
  Silver 2      
  Technetium 0.2       
  Thallium 1      
  Tin 50      
  Uranium 5      
  Vanadium 2      
   Zinc 86 200 360


  Aldrin       0.1
  Benzene hexachloride (including lindane)       6
  Chlordane      1 2.7
  DDT/DDD/DDE (total)       0.75
  Dieldrin       0.07
  Endrin       0.2
  Hexachlorobenzene       17
  Heptachlor/heptachlor epoxide (total)       0.4
  Pentachlorophenol 3 6 4.5


  1,2,3,4-Tetrachlorobenzene    10   
  1, 2,3-Trichlorobenzene    20   
  1,2,4-Trichlorobenzene    20   
  1,2-Dichloropropane    700   
  1,4-Dichlorobenzene    20   
  2,3,4,5-Tetrachlorophenol    20   
  2,3,5,6-Tetrachloroaniline 20 20   
  2,4,5-Trichloroaniline 20 20   
  2,4,5-Trichlorophenol 4 9   
  2,4,6-Trichlorophenol      10   
  2,4-Dichloroaniline    100   
  3,4-Dichloroaniline   20   
  3,4-Dichlorophenol 20 20   
  3-Chloroaniline 20 30   
  3-Chlorophenol 7 10   
  Chlorinated dibenzofurans (total)       2E-06
  Chloroacetamide    2   
  Chlorobenzene    40   
  Dioxins      2E-06
  Hexachlorocyclopentadiene 10      
  PCB mixtures (total) 40    0.65
  Pentachloroaniline   100   
  Pentachlorobenzene    20   


  2,4-Dinitrophenol 20      
  4-Nitrophenol   7   
  Acenaphthene 20      
  Benzo(a)pyrene       12
  Biphenyl 60      
  Diethylphthalate 100      
  Dimethylphthalate    200   
  Di-n-butyl phthalate 200      
  Fluorene    30   
  Furan 600      
  Nitrobenzene    40   
  N-nitrosodiphenylamine    20   
  Phenol 70 30     
  Styrene 300      
  Toluene 200      


Gasoline Range Organics    100 5,000 mg/kg

except that the concentration shall not exceed residual saturation at the soil surface.

Diesel Range Organics    200 6,000

except that the concentration shall not exceed residual saturation at the soil surface.

Table 749-3  Notes 

a    Caution on misusing ecological indicator concentrations.  Exceedances of the values in this table do not necessarily trigger requirements for cleanup action under this chapter.  Natural background concentrations may be substituted for ecological indicator concentrations provided in this table.  The table is not intended for purposes such as evaluating sludges or wastes.

This list does not imply that sampling must be conducted for each of these chemicals at every site.  Sampling should be conducted for those chemicals that might be present based on available information, such as current and past uses of chemicals at the site.

b    For hazardous substances where a value is not provided, plant and soil biota indicator concentrations shall be based on a literature survey conducted in accordance with WAC 173-340-7493(4) and calculated using methods described in the publications listed below in footnotes c and d.  Methods to be used for developing wildlife indicator concentrations are described in Tables 749-4 and 749-5.

c    Based on benchmarks published in Toxicological Benchmarks for Screening Potential Contaminants of Concern for Effects on Terrestrial Plants:  1997 revision, Oak Ridge National Laboratory, 1997.

    Based on benchmarks published in Toxicological Benchmarks for Potential Contaminants of Concern for Effects on Soil and Litter Invertebrates and Heterotrophic Process, Oak Ridge National Laboratory, 1997.

e    Calculated using the exposure model provided in Table 749-4 and chemical-specific values provided in Table 749-5. Where both avian and mammalian values are available, the wildlife value is the lower of the two.

   For arsenic, use the valence state most likely to be appropriate for site conditions, unless laboratory information is available.  Where soil conditions alternate between saturated, anaerobic and unsaturated, aerobic states, resulting in the alternating presence of arsenic III and arsenic V, the arsenic III concentrations shall apply.

g    Benchmark replaced by Washington state natural background concentration.

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