[Code of Federal Regulations]
[Title 40, Volume 22]
[Revised as of July 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR258.23]

[Page 399-400]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 258--CRITERIA FOR MUNICIPAL SOLID WASTE LANDFILLS--Table of Contents
 
                      Subpart C--Operating Criteria
 
Sec. 258.23  Explosive gases control.

    (a) Owners or operators of all MSWLF units must ensure that:
    (1) The concentration of methane gas generated by the facility does 
not exceed 25 percent of the lower explosive limit for methane in 
facility structures (excluding gas control or recovery system 
components); and
    (2) The concentration of methane gas does not exceed the lower 
explosive limit for methane at the facility property boundary.
    (b) Owners or operators of all MSWLF units must implement a routine 
methane monitoring program to ensure that the standards of paragraph (a) 
of this section are met.
    (1) The type and frequency of monitoring must be determined based on 
the following factors:
    (i) Soil conditions;
    (ii) The hydrogeologic conditions surrounding the facility;
    (iii) The hydraulic conditions surrounding the facility; and
    (iv) The location of facility structures and property boundaries.
    (2) The minimum frequency of monitoring shall be quarterly.
    (c) If methane gas levels exceeding the limits specified in 
paragraph (a) of this section are detected, the owner or operator must:
    (1) Immediately take all necessary steps to ensure protection of 
human health and notify the State Director;
    (2) Within seven days of detection, place in the operating record 
the methane gas levels detected and a description of the steps taken to 
protect human health; and
    (3) Within 60 days of detection, implement a remediation plan for 
the methane gas releases, place a copy of the plan in the operating 
record, and notify

[[Page 400]]

the State Director that the plan has been implemented. The plan shall 
describe the nature and extent of the problem and the proposed remedy.
    (4) The Director of an approved State may establish alternative 
schedules for demonstrating compliance with paragraphs (c) (2) and (3) 
of this section.
    (d) For purposes of this section, lower explosive limit means the 
lowest percent by volume of a mixture of explosive gases in air that 
will propagate a flame at 25 deg. C and atmospheric pressure.
    (e) The Director of an approved State may establish alternative 
frequencies for the monitoring requirement of paragraph (b)(2) of this 
section, after public review and comment, for any owners or operators of 
MSWLFs that dispose of 20 tons of municipal solid waste per day or less, 
based on an annual average. Any alternative monitoring frequencies 
established under this paragraph must:
    (1) Consider the unique characteristics of small communities;
    (2) Take into account climatic and hydrogeologic conditions; and
    (3) Be protective of human health and the environment.

[56 FR 51016, Oct. 9, 1991, as amended at 62 FR 40713, July 29, 1997]