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period of time. As the liquid waste percolates through the soil, its arsenic concentration <br /> will be reduced by various attenuative mechanisms, such as adsorption and precipitation. <br /> If these mechanisms are not capable of reducing the arsenic concentration sufficiently (high <br /> permeability soils and/or insufficient separation between the waste and ground water), • <br /> enough arsenic will enter ground water to cause the drinking water standard to be <br /> exceeded. Its beneficial use for domestic supply would be impaired. In this situation the <br /> waste would be classified as a 'designated waste'. <br /> It can be seen from the example above that: 1) the classification of a waste as 'hazardous' is <br /> made purely on waste-specific factors,while the classification of a waste as 'designated' <br /> must be based on both waste-and site-specific factors; and 2) the 'hazardous waste' <br /> classification system is insufficient to protect all waters of the State from the discharge of <br /> wastes to land. Subchapter 15 provides no guidance to the Regional Boards on how to <br /> determine whether a non-'hazardous' waste should be classified as 'designated other than <br /> the language in§2522, quoted above. A methodology for making these decisions is <br /> provided in Chapter 3 of this report. <br /> Subchapter 15 requires 'designated wastes' to be discharged to Class I or Class II waste <br /> management units. These units are to be designed to isolate the wastes from the <br /> surrounding environment through natural and/or engineered controls. Under§2520(a)(1) <br /> of Subchapter 15, a Title 22 'hazardous waste' that is given a variance by DHS may be <br /> discharged to a Class III waste management unit if the discharger demonstrates to the <br /> appropriate Regional Board that the waste does not pose a significant threat to water <br /> quality(see Figure 2). Only rarely will the discharger be able to make this demonstration. <br /> An example of a waste for which this demonstration is appropriate is asbestos. Wastes <br /> containing over 1.0 % asbestos are 'hazardous' under Title 22;however,DHS has granted <br /> asbestos a variance from hazardous waste management if these wastes are double-bagged <br /> and covered immediately after discharge. If discharged to a Class III landfill,the asbestos_ <br /> does not pose a threat to ground water quality, since asbestos fibers are unable to migrate <br /> ---through soils. The-Regional-Boards,therefore,frequently grant a§2520(a)(1)variance from <br /> Class II disposal for these 'designated wastes'. <br /> 2.4 Nonhazardous Solid Wastes' and Inert'Wastes <br /> Wastes in the remaining two classifications of Subchapter 15 are not required to be <br /> discharged to waste management units which provide isolation from the surrounding <br /> environment. Nonhazardous solid waste' is more commonly referred to as "municipal <br /> solid waste" or "refuse". It contains a significant quantity of degradable materials,but <br /> cannot contain 'designated waste . Examples of'nonhazardous solid waste' include solid <br /> refuse from foodprocessing and handling,paper products, cardboard,wood,rubber,tree <br /> prunings,and dead animals. Subchapter 15 allows 'nonhazardous solid waste' to be <br /> discharged to Class III waste management units which are located and/or <br /> designed to prevent impairment of beneficial uses of nearby ground and surface waters. <br /> Thus,limited or controlled leakage of leachate from the waste to the surrounding <br /> environment is permitted. <br /> Designated Level Methodology Page 17 <br />