[Code of Federal Regulations]

[Title 40, Volume 24]

[Revised as of July 1, 2006]

From the U.S. Government Printing Office via GPO Access

[CITE: 40CFR258.54]



[Page 418-419]

 

                   TITLE 40--PROTECTION OF ENVIRONMENT

 

         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)

 

PART 258_CRITERIA FOR MUNICIPAL SOLID WASTE LANDFILLS--Table of Contents

 

         Subpart E_Ground-Water Monitoring and Corrective Action

 

Sec.  258.54  Detection monitoring program.



    (a) Detection monitoring is required at MSWLF units at all ground-

water monitoring wells defined under Sec. Sec.  258.51 (a)(1) and (a)(2) 

of this part. At a minimum, a detection monitoring program must include 

the monitoring for the constituents listed in appendix I to this part.

    (1) The Director of an approved State may delete any of the appendix 

I monitoring parameters for a MSWLF unit if it can be shown that the 

removed constituents are not reasonably expected to be in or derived 

from the waste contained in the unit.

    (2) The Director of an approved State may establish an alternative 

list of inorganic indicator parameters for a MSWLF unit, in lieu of some 

or all of the heavy metals (constituents 1-15 in appendix I to this 

part), if the alternative parameters provide a reliable indication of 

inorganic releases from the MSWLF unit to the ground water. In 

determining alternative parameters, the Director shall consider the 

following factors:

    (i) The types, quantities, and concentrations of constituents in 

wastes managed at the MSWLF unit;

    (ii) The mobility, stability, and persistence of waste constituents 

or their reaction products in the unsaturated zone beneath the MSWLF 

unit;

    (iii) The detectability of indicator parameters, waste constituents, 

and reaction products in the ground water; and

    (iv) The concentration or values and coefficients of variation of 

monitoring parameters or constituents in the groundwater background.

    (b) The monitoring frequency for all constituents listed in appendix 

I to thispart, or in the alternative list approved in accordance with 

paragraph (a)(2) of this section, shall be at least semiannual during 

the active life of the facility (including closure) and the post-closure 

period. A minimum of four independent samples from each well (background 

and downgradient) must be collected and analyzed for the appendix I 

constituents, or the alternative list approved in accordance with 

paragraph (a)(2) of this section, during the first semiannual sampling 

event. At least one sample from each well (background and downgradient) 

must be collected and analyzed during subsequent semiannual sampling 

events. The Director of an approved State may specify an appropriate 

alternative frequency for repeated sampling and analysis for appendix I 

constituents, or the alternative list approved in accordance with 

paragraph (a)(2) of this section, during the active life (including 

closure) and the post-closure care period. The alternative frequency 

during the active life (including closure) shall be no less than annual. 

The alternative frequency shall be based on consideration of the 

following factors:

    (1) Lithology of the aquifer and unsaturated zone;

    (2) Hydraulic conductivity of the aquifer and unsaturated zone;

    (3) Ground-water flow rates;

    (4) Minimum distance between upgradient edge of the MSWLF unit and 

downgradient monitoring well screen (minimum distance of travel); and

    (5) Resource value of the aquifer.



[[Page 419]]



    (c) If the owner or operator determines, pursuant to Sec.  258.53(g) 

of this part, that there is a statistically significant increase over 

background for one or more of the constituents listed in appendix I to 

this part or in the alternative list approved in accordance with 

paragraph (a)(2) of this section, at any monitoring well at the boundary 

specified under Sec.  258.51(a)(2), the owner or operator:

    (1) Must, within 14 days of this finding, place a notice in the 

operating record indicating which constituents have shown statistically 

significant changes from background levels, and notify the State 

director that this notice was placed in the operating record; and

    (2) Must establish an assessment monitoring program meeting the 

requirements of Sec.  258.55 of this part within 90 days except as 

provided for in paragraph (c)(3) of this section.

    (3) The owner/operator may demonstrate that a source other than a 

MSWLF unit caused the contamination or that the statistically 

significant increase resulted from error in sampling, analysis, 

statistical evaluation, or natural variation in ground-water quality. A 

report documenting this demonstration must be certified by a qualified 

ground-water scientist or approved by the Director of an approved State 

and be placed in the operating record. If a successful demonstration is 

made and documented, the owner or operator may continue detection 

monitoring as specified in this section. If, after 90 days, a successful 

demonstration is not made, the owner or operator must initiate an 

assessment monitoring program as required in Sec.  258.55.