MEMORANDUM 

SUBJECT: Techni·cal Guidance Reviewed by US EPA for 40 CFR Parts 257 and 261, [EPAHQ-RCRA-2009-0640; FRL-9149-4], RIN-2050-AE81 , Hazardous and Solid 

Waste Management System; Disposal of Coal Combustion Residuals from 

Electric Utilities. 

FROM: Patrick M. Kelly, P.E. 

Environmental Engineer 

Office of Solid Waste and Emergency Response 

TO: Docket 

DATE: Thursday, December 18, 2014 

Upon the initiation of the CCR Surface Impoundment Assessment effort, EPA considered a 

number of regulation and guidance in developing a criteria to determine structural adequacy and 

safety of CCR Surface Impoundments. EPA requested of its engineering contractor Dewberry 

and Davis to provide recommendations regarding what guidance or regulations would be 

appropriate in order to determine the overall structural and safety adequacy of the CCR surface 

impoundments. 

Attached is a memo sent from Dewberry and Davis personnel to EPA personnel offering 

recommendation for appropriate guidance and regulation for dam safety. EPA reviewed and in 

some instances based final regulatory text on these guidance and regulations, in addition to 

additional guidances which EPA reviewed, in the CCR Surface Impoundment Assessments and 

additionally in the finalization of the CCR final rule 40 CFR Parts 257 and 261, [EPA-HQRCRA-2009-0640; FRL-9149-4], RIN-2050-AE81, Hazardous and Solid Waste Management 

System; Disposal of Coal Combustion Residuals from Electric Utilities. 
tJ Dewberry 

Memorandtun 

To: Jerry Strauss, PE 

CC: File 

From: Fred C. Tucker, PE 

Date: December 12, 20 II 

8401 Arlington Boulevard 

Fairfax, Virginia 22031-4666 

703 849 0100 

703 206 0803 fax 

www.dewberry.com 

Re: Appropriate Stability Analysis Guidance Documents for CCR Impoundment Dikes 

The U.S. Army Corps of Engineers (USACE) is usually the best resource for engineering and 

technical guidance not dictated by other agencies such as the US Bureau of Reclamation, 

Natural Resources Conservation Service, Federal Energy Regulatory Commission, US Forest 

Service, etc. Appropriate guidance on slope stability is contained in the U_SACE~ Enginlli 

l EM 111 0-2-1902 "Slo e Stabilit "dated 31 October 2003. The earlier version of 

EM 111 0-2-1902, which was then titled "Stability ofEarth an ock-Fill Dams," dated I 

April 1970, may also be useful, particularly when performing screening asse ssm,~ nts of dams 

or dikes constructed prior to about 1983 , when the USACE began to change policy and 

procedures in analysis of embankment dams under earthquake loading. The later version of 

EM 1110-2-1902 does not cover earthquake loading, but general guidance on earthquake 

design is given in ngineer Re ulation ER 1110-2-1806, "Earthquake Desi nand Evaluation 

fi r Civ' ro·ect," dated 31 5. Interim gmdance is given in Engineer 

Technical Letter ETL 1110-2-301, " Interim Procedure for Specifying Earthquake Motions," 

•. dated 26 August 1983. Guidance on dam safety is given in EC 111 0-2-6061 , "Safety of 

I 

Dams-Policy and Procedures," dated 30 April 2004. Comprehensive guidance is being . 

developed in Engineer Circular EC 1110-2-6000, "Selection of Design Earthquakes and 

Associated Ground Motions," draft dated 10 July 2008 and in EC 11 1 0-2-600 I, "Dynamic 

Stability of Embankment Dams," draft dated 4 February 2004. 

Alternative guidance may be found in the Engineering and Design Manual for Coal Refuse 

Disposal Facilities (Manual), originally published by the Mining Enforcement and Safety 

Administration (MESA) in 1975 and updated for the Mine Safety and Health Administration 

(MSHA) in May 2009, in particular Chapter 6, "Geotechnical Exploration, Material Testing, 

Engineering Analysis and Design," and Chapter 7, "Seismic Design: Stability and 

Deformation Analyses." 
The following federal guidelines are used for seismic analyses of earthen 

dams: 

Analyses for earthquake loading begin with simplified procedures and 

evaluated by the pseudo-static method using the seismic coefficient to t he 

seismic zone (developed by USACE) for the project. 

USACE ER 1110-2-1806 

d. Estimating OBE and MOE ground motions. 

Estimates are usually made in two phases. The first 

estimates are used as a starting point for the study and 

are obtained from the National Earthquake Hazard 

Reduction Program (NEHRP) spectral acceleration maps. The second phase 

is more site-specific, used for critical structures (eg ., nuclear plants) and not 

usually used for impoundment dikes. 

National Earthquake Hazard 

Reduction Program (NEHRP) Spectral Acceleration Maps 

The reference for seismic loading is USGS Seismic-Hazard Maps for the 

Conterminous United States, Horizontal Spectral Response Acceleration for 

1. a-second Period (5 Percent of Critical Damping) with 2 Percent 

Probability of Exceedance in SO Years. (i.e. probable earthquake within 

2,500 years). 

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