July 24, 1997

MEMORANDUM

TO:         RCRA Dockets F-97-FLXF-FFFFF & F-97-FLXP-FFFFF

FROM:       Allen J. Geswein, Environmental Engineer

SUBJECT:    Daily Cover Requirements for MSWLFs




      Under 40 CFR Part 258.21(a), "owners or operators of all
municipal solid waste landfill (MSWLF) units must cover disposed
solid waste with 6 inches of earthen material at the end of each
operating day, or at more frequent intervals if necessary, to
control disease vectors, fires, odors, blowing litter, and
scavenging."  These requirements were promulgated under the Solid
Waste Disposal Facility Criteria Final Rule on October 9, 1991, to
protect human health and the environment. 

      The rationale behind requiring 6 inches of cover is two-fold:

            PEST AND DISEASE CONTROL.  Data show that 6 inches of
            compacted sandy loam are necessary to prevent fly     
            emergence from the landfilled materials (U.S. EPA,    
            1988b).  Data also show that 6 inches of material or  
            more is sufficient to control rodents and other disease 
            vectors, such as mosquitos  (U.S. EPA, 1991).

            EASE OF IMPLEMENTATION.  In promulgating the daily    
            cover requirement, the Agency believed that requiring 
            6 inches of earthen material would be easy to implement
            and enforce.  At the time, 45 States and Territories  
            already specifically required 6 inches of earthen     
            material as daily cover and the practice was already  
            standard operating procedure at most MSWLFs (U.S. EPA, 
            1991).  These states and territories had required daily
            cover for at least 10 years prior to 1991, and the    
            federal government had required it for nearly 20 years.

      There are several reasons why EPA requires daily application
of cover, as listed below.  EPA believes that cover material
applied less frequently will not be as effective in meeting these
purposes. 

            DISEASE VECTOR CONTROL.  Daily cover helps to control 
            disease vectors by curbing birds, insects, and rodents,
            which represent the principal pathways of human disease
            transmission (U.S. EPA, 1988a).  Daily or more frequent
            cover has been shown to reduce food sources and       
            breeding environments for birds and rodents (U.S. EPA, 
            1988b).  Daily cover also prevents insect emergence   
            from waste (U.S. EPA, 1988b).

            ODOR AND AIR EMISSION CONTROL.  Daily cover prevents  
            direct contact of wind and disposed waste and thereby 
            reduces odors and air emissions that might be caused by
            daily disposal of waste (U.S. EPA, 1988b).  These     
            nuisances can be aesthetically displeasing as well as 
            threatening to human health and the environment (U.S. 
            EPA, 1991).

            GROUND-WATER AND SURFACE WATER PROTECTION.  Daily cover
            reduces rainwater infiltration by increasing runoff,  
            therefore reducing leachate generation and the        
            potential for surface and ground-water contamination  
            (U.S. EPA, 1988b).  

            FIRE PREVENTION.  Daily cover lessens the risk and    
            spread of fires by reducing exposure of combustible   
            materials to ignition sources (U.S. EPA, 1988b).  Daily
            cover also provides a firebreak to prevent flames from 
            spreading throughout a landfill.

            LITTER CONTROL.  Daily cover enhances the site        
            appearance by preventing blowing litter (U.S. EPA,    
            1988a).  In addition, by removing the waste from      
            observation, scavenging is discouraged.

            VEHICLE ACCESS.  Daily cover provides a more stable   
            surface for vehicles to use when necessary.  

            IMPROVED PUBLIC PERCEPTION.  Daily cover increases the 
            site appearance of a landfill site as well as the     
            overall perception of the site by preventing potential 
            environmental, health, and other problems mentioned   
            above (U.S. EPA, 1988b).

Resources Used:

U.S. EPA. 1988a. Draft background document; operating criteria
(Subpart C); "Criteria for municipal solid waste landfills."
Washington, DC. July.

U.S. EPA. 1988b. 40 CFR Parts 257 and 258, Solid Waste Disposal
Facility Criteria; Proposed Rule. 53 Federal Register 33314.
Washington, DC. August 30.

U.S. EPA. 1991. 40 CFR Parts 257 and 258, Solid Waste Disposal
Facility Criteria; Final Rule. 56 Federal Register 50978.
Washington, DC. October 9.

U.S. EPA. 1993. Solid waste disposal facility criteria: Technical
manual. Washington, DC. November.

U.S. EPA. 1994.  Seminar publication: Design, operation, and
closure of municipal solid waste landfills. Washington, DC.
September.