A System’s Guide to the 

Identification and Disposal of 

Hazardous and NonHazardous Water Treatment 

Plant Residuals 

Drinking water systems producing solid waste are required under the Resource Conservation and Recovery Act

 (RCRA) to determine whether that waste is hazardous. These requirements are described in this document in 

summary form only; you need to consult the statutory and regulatory provisions that are applicable to the waste you 

generate or manage in order to determine the requirements with which you must comply. This document also provides 

additional recommendations and information on possible options; these are not regulatory requirements and are provided 

for your information only. EPA will continue to review and update this Guide as necessary and appropriate. 

RCRA’s definition of solid waste (40 CFR 261.2) is broad,1

 encompassing all wastes that a water treatment plant (WTP) 

would produce, including liquid residuals, solid residuals, and sludge. Although most water systems can avoid generating 

hazardous wastes, some WTP residuals may contain certain contaminants, such as arsenic, in high enough concentrations 

to be classified as hazardous. For additional information on RCRA, see www.epa.gov/epaoswer/osw/laws-reg.htm. 

1 Solid waste includes any garbage; refuse; sludge from a wastewater treatment plant, water supply treatment plant, or air pollution control facility; 

and other discarded material, including solid, liquid, semisolid, or contained gaseous material, resulting from industrial, commercial, mining, and 

agricultural operations and from community activities. 
WTP Residuals 

Hazardous waste regulations vary 

The following sections summarize the steps you must take to determine whether from state to state. It is important

your residuals are hazardous, your generator status if you are generating or storing to check with your primacy agency 

to determine whether you need to hazardous waste, and your disposal options for hazardous and non-hazardous meet additional requirements. residuals. 

STEP 1: WASTE IDENTIFICATION 

WTP waste identification is a two-step process: 

1. Determine whether the waste is hazardous using your 

knowledge of the waste generation process, analytical 

testing, or a combination of both. See Decision Tree 1 

on page 4 for additional information on hazardous 

waste identification. 

• Process knowledge is detailed information on the 

processes that create wastes (i.e., does the process 

concentrate or dilute the waste?). It can be obtained 

by reviewing treatment schematics and plans, 

published waste analysis data or studies on similar 

treatment processes, or data from other treatment 

facilities, among other things. Note that if you use 

process knowledge alone to characterize the waste, 

you will be held responsible for any inaccurate 

determinations. 

• Analytical testing may involve leachate tests such 

as the Toxicity Characteristic Leaching Procedure 

(TCLP) (EPA Method 1311), which is designed to 

determine the mobility of both organic and inorganic analytes present in liquid, solid, and 

multiphasic wastes. The TCLP predicts if hazardous components of a waste are likely to leach out 

and become a threat to public health or the environment. Testing should always be done by a qualified 

laboratory and while analytical testing can be more 

expensive, it usually provides more accurate information on waste characteristics. Table 1 contains 

maximum concentrations for the toxicity characteristics for inorganic contaminants. 

Mixed Waste 

Mixed waste “contains both hazardous waste and source... or 

byproduct material subject to the Atomic Energy Act [AEA]...” 

(42 USC 6903.41). Mixed waste is regulated under both RCRA 

and AEA, and although highly unlikely, WTPs generating hazardous waste could have a mixed waste if the residuals also contain 

more than 0.05 percent by weight of uranium or thorium (i.e., 

source material). 

A system generating hazardous waste does not have mixed waste 

if the amount of source material generated is an “unimportant 

quantity” (uranium or thorium makes up less than 0.05 percent by 

weight of the material), or if the waste contains only radium since 

radium is not considered source or by-product material when 

present in water treatment residuals unless it co-occurs with 

licensable source material such as uranium. Your primacy agency 

may have additional regulations for water treatment plant residuals 

containing radium. 

Hazardous wastes containing source material exceeding the 

“unimportant quantity” limits, must be disposed of at a facility 

authorized to accept mixed waste. Because there are extremely 

limited mixed waste disposal options, generation of a mixed waste 

should be avoided if at all possible. 

For additional information, see EPA’s A System’s Guide to the 

Management of Radioactive Residuals from Drinking Water Treatment 

Technologies (EPA 816-F-06-012) or contact your primacy agency. 

For more information on process knowledge and analytical testing, see www.epa.gov/epaoswer/non-hw/industd/chapters/ 

chap2.pdf and www.epa.gov/sw-846/index.htm. 

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2. Determine if your hazardous and/or non-hazardous waste 

contains any “free liquids” by having a lab perform the Paint Table 1: Maximum Concentration of Inorganic 

Filter Liquids Test (PFLT) (EPA SW 846 Method 9095). Land- Contaminants for the Toxicity Characteristic 

fills cannot accept waste containing free liquids and therefore 

you will need to use an intermediate processing method (such as 

dewatering) to remove any liquids. Your system will need to find 

an appropriate method for disposing of the liquid residuals 

generated by the intermediate processing. 

If your system is producing non-hazardous wastes, your disposal 

options for solid residuals are regulated under RCRA Subtitle D, 

while hazardous solid wastes are regulated under RCRA Subtitle 

C. Disposal options for both non-hazardous and hazardous 

liquids are regulated under the Safe Drinking Water Act (SDWA) 

Underground Injection Control (UIC) provisions or the Clean Note: See 40 CFR 261.24 for other contaminants.

Water Act (CWA) regulations. See Step 3 for more information

on disposal options.

STEP 2: DETERMINE YOUR GENERATOR STATUS AND REQUIREMENTS 

In accordance with RCRA, hazardous waste generators are classified into categories based on the amount of hazardous 

waste produced monthly and the amount of hazardous waste stored on-site. Your generator status determines your 

requirements. See Table 2, below, for the

definition of each generator group. Table 2: Generator Status and Requirements

If you have obtained CESQG status, and you 

exceed either the generation or the storage 

limit in any given month, you will lose your 

CESQG status and must comply with more 

stringent requirements for SQGs or LQGs (40 

CFR 262.10(b)). 

CESQGs are required under RCRA (40 CFR 261.5) to: 

1. Identify all hazardous waste that is generated.

2. Comply with the storage limit requirement (less than 1,000 kg) and maintain an inventory to track the amount of waste

generated each month and stored on-site. 

3. Ensure proper on-site or off-site waste treatment or disposal at a:

• Licensed primacy agency hazardous waste facility 

• Permitted or interim status hazardous waste Treatment, Storage, and Disposal Facility (TSDF) 

• Primacy agency permitted, licensed, or registered solid waste disposal facility (including a municipal solid waste

landfill)

• Recycling facility 

• Universal waste facility 

Not all primacy agencies recognize the CESQG category. Contact your primacy agency’s drinking water or hazardous

waste program for more information.

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1 40 CFR 261.4(b) lists solid wastes that are excluded from regulations as hazardous waste. 

solid wastes and are thus excluded from regulation under RCRA. 

return flow; Atomic Energy Act (AEA) source, special nuclear, or by-product material; or, in-situ mining waste. 

2 40 CFR 261 Subpart D lists hazardous wastes subject to RCRA regulation. 

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(including a waste that is excluded from a particular facility from the lists in 40 CFR Subpart D). 

Note that 40 CFR 261.4(a) lists materials that are not 

These materials include: domestic sewage; CWA point source discharge; irrigation 

 40 CFR 261.3 includes the definition of hazardous waste as a solid waste that is not excluded from regulation in 40 CFR 261.4(b), and is listed in 

40 CFR Subpart D, or exhibits a characteristic of hazardous waste identified in 40 CFR Subpart C (i.e., ignitability, corrosivity, reactivity, or toxicity). 

 40 CFR 260.20 and 260.22 provide an opportunity for any person to petition the EPA Administrator to modify or revoke any part of 40 CFR 261 

Decision Tree 1: Hazardous Waste Determination 

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STEP 2, continued 

If you generate or store enough waste to be considered a SQG or LQG, you will be subject to further RCRA regulations 

(40 CFR 262). These include: obtaining an EPA identification number (generally from the primacy agency); complying 

with waste accumulation and storage requirements; developing emergency plans; training employees; following the manifest system and Department of Transportation (DOT) requirements for off-site hazardous waste shipments; and 

recordkeeping and reporting requirements. SQGs and LQGs that plan on storing waste beyond certain time limits must 

also obtain a RCRA storage permit. Time limits vary according to waste quantity and factors, as described in 40 CFR 

262.34. 

If your system is a CESQG, you are not required to comply with most of the regulations described above. However, you 

should follow safe management practices when storing hazardous waste on-site, including: 

• Carefully labeling and sealing hazardous waste containers 

• Maintaining and frequently inspecting the areas where hazardous waste is stored to minimize the chance of leaks 

• Posting emergency response telephone numbers and making sure that there is an easily accessible telephone in or 

near the storage facility 

• Ensuring that system staff are aware of the dangers and are properly trained to handle hazardous waste 

• Preparing containers for transportation by packaging, labeling, and marking them according to DOT regulations (49 

CFR 172; see www.access.gpo.gov/nara/cfr/waisidx_02/49cfr172_02.html) 

Transporting Waste 

The transporter or disposal facility may require CESQGs to have an EPA Hazardous Waste 

Generator ID number. For more information on this, see EPA’s “Notification of Regulated 

Waste Activity Instructions and Form Booklet” at www.epa.gov/epaoswer/hazwaste/data/ 

form8700/forms.htm. 

CESQGs may not be required to prepare a Uniform Hazardous Waste Manifest for the waste 

transporter. However, the manifest is a good record of your system’s hazardous waste 

disposal and transportation activities. Contact your primacy agency for information on 

licensed hazardous waste transporters and see: www.epa.gov/epaoswer/hazwaste/gener/manifest. 

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1

 Direct discharges subject to NPDES permits are not solid or hazardous waste under RCRA. Wastewater that is stored

the definition in 40 CFR 260.10 would be exempt from RCRA permitting requirements.

2

 In accordance with UIC regulations (10 CFR 20 Appendix B, Table 2, Column 2), EPA considers wastes with the

300 pCi/L for uranium.

STEP 3: DISPOSAL
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before discharge is a solid waste under RCRA and may be a hazardous waste; however, wastewater treatment tanks that meet

following concentrations of radium and uranium to be radioactive: 60 pCi/L for radium-226, 60 pCi/L for radium-228, and
Resources 

Documents 

• Guide for Industrial Waste Management, EPA 530-R-03-001, April 2003

(www.epa.gov/epaoswer/non-hw/industd/guide.htm)

• How Does RCRA Work?, EPA 530-E-00-001c, October 2000

(www.epa.gov/epaoswer/general/manag-hw/e00-001c.pdf)

• What Makes a Waste Hazardous?, EPA 530-E-00-001e, October 2000

(www.epa.gov/epaoswer/general/manag-hw/e00-001e.pdf)

• RCRA Orientation Manual, EPA 530-R-02-016, January 2003

(www.epa.gov/epaoswer/general/orientat)

• Reducing Risk from Waste, EPA 530-K-97-004, September 1997

(www.epa.gov/epaoswer/general/risk/risk.htm)

• Department of Labor, Occupational Safety and Health Administration Hazardous Waste Standards 

(www.osha.gov/SLTC/hazardouswaste/standards.html) 

Web Sites 

• EPA: www.epa.gov 

• EPA Office of Ground Water and Drinking Water: www.epa.gov/safewater 

• EPA Office of Solid Waste: www.epa.gov/osw 

• EPA Office of Air and Radiation: www.epa.gov/radiation 

• EPA Office of Wastewater Management, NPDES: cfpub.epa.gov/npdes 

• RCRA Online: www.epa.gov/rcraonline 

• Regulations and Standards - RCRA: www.epa.gov/epaoswer/osw/laws-reg.htm#RCRA 

• Underground Injection Control: www.epa.gov/safewater/uic.html 

• Paint Filter Liquids Test: www.epa.gov/epaoswer/hazwaste/test/pdfs/9095a.pdf 

• Department of Transportation, Office of Hazardous Materials Safety: hazmat.dot.gov 

• U.S. Nuclear Regulatory Commission: www.nrc.gov 

Safe Drinking Water Hotline 

1-800-426-4791 

Office of Water (4606M) 

EPA 816-F-06-011 

www.epa.gov 

August 2006 

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