[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: 40CFR257.24]



[Page 387-388]

 

                   TITLE 40--PROTECTION OF ENVIRONMENT

 

         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)

 

PART 257_CRITERIA FOR CLASSIFICATION OF SOLID WASTE DISPOSAL FACILITIES 

AND PRACTICES--Table of Contents

 

  Subpart B_Disposal Standards for the Receipt of Conditionally Exempt 

 Small Quantity Generator (CESQG) Wastes at Non-Municipal Non-Hazardous 

                          Waste Disposal Units

 

Sec.  257.24  Detection monitoring program.



    (a) Detection monitoring is required at facilities identified in 

Sec.  257.5(a) at all ground-water monitoring wells defined under 

Sec. Sec.  257.22 (a)(1) and (a)(2). At a minimum, a detection 

monitoring program must include the monitoring for the constituents 

listed in appendix I of 40 CFR part 258.

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

I (Appendix I of 40 CFR part 258) monitoring parameters for a unit if it 

can be shown that the removed constituents are not reasonably expected 

to be contained in or derived from the waste contained in the unit.

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

list of indicator parameters for a unit, in lieu of some or all of the 

constituents in appendix I to 40 CFR part 258, if the alternative 

parameters provide a reliable indication of releases from the 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 

waste managed at the unit;

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

or their reaction products in the unsaturated zone beneath the 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 40 CFR part 258, 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



[[Page 388]]



the unit plus 30 years. A minimum of four independent samples from each 

well (background and downgradient) must be collected and analyzed for 

the appendix I (Appendix I of 40 CFR part 258) 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 (Appendix I of 40 CFR part 

258) constituents, or the alternative list approved in accordance with 

paragraph (a)(2) of this section, during the active life plus 30 years. 

The alternative frequency during the active life 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 unit and 

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

    (5) Resource value of the aquifer.

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

257.23(g), that there is a statistically significant increase over 

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

40 CFR part 258, 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.  257.22(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.  257.25 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 the 

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.  257.25.