[Code of Federal Regulations]
[Title 40, Volume 24]
[Revised as of July 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR264.280]

[Page 341-342]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 264_STANDARDS FOR OWNERS AND OPERATORS OF HAZARDOUS WASTE TREATMENT, 
STORAGE, AND DISPOSAL FACILITIES--Table of Contents
 
                        Subpart M_Land Treatment
 
Sec. 264.280  Closure and post-closure care.

    (a) During the closure period the owner or operator must:
    (1) Continue all operations (including pH control) necessary to 
maximize degradation, transformation, or immobilization of hazardous 
constituents within the treatment zone as required under Sec. 
264.273(a), except to the extent such measures are inconsistent with 
paragraph (a)(8) of this section.
    (2) Continue all operations in the treatment zone to minimize run-
off of hazardous constituents as required under Sec. 264.273(b);
    (3) Maintain the run-on control system required under Sec. 
264.273(c);
    (4) Maintain the run-off management system required under Sec. 
264.273(d);
    (5) Control wind dispersal of hazardous waste if required under 
Sec. 264.273(f);
    (6) Continue to comply with any prohibitions or conditions 
concerning growth of food-chain crops under Sec. 264.276;
    (7) Continue unsaturated zone monitoring in compliance with Sec. 
264.278, except that soil-pore liquid monitoring may be terminated 90 
days after the last application of waste to the treatment zone; and
    (8) Establish a vegetative cover on the portion of the facility 
being closed at such time that the cover will not substantially impede 
degradation, transformation, or immobilization of hazardous constituents 
in the treatment zone. The vegetative cover must be capable of 
maintaining growth without extensive maintenance.
    (b) For the purpose of complying with Sec. 264.115, when closure is 
completed the owner or operator may submit to the Regional Administrator 
certification by an independent qualified soil scientist, in lieu of an 
independent registered professional engineer, that the facility has been 
closed in accordance with the specifications in the approved closure 
plan.
    (c) During the post-closure care period the owner or operator must:
    (1) Continue all operations (including pH control) necessary to 
enhance degradation and transformation and sustain immobilization of 
hazardous constituents in the treatment zone to the extent that such 
measures are consistent with other post-closure care activities;
    (2) Maintain a vegetative cover over closed portions of the 
facility;
    (3) Maintain the run-on control system required under Sec. 
264.273(c);
    (4) Maintain the run-off management system required under Sec. 
264.273(d);
    (5) Control wind dispersal of hazardous waste if required under 
Sec. 264.273(f);
    (6) Continue to comply with any prohibitions or conditions 
concerning growth of food-chain crops under Sec. 264.276; and
    (7) Continue unsaturated zone monitoring in compliance with Sec. 
264.278, expect that soil-pore liquid monitoring may be terminated 90 
days after the last application of waste to the treatment zone.
    (d) The owner or operator is not subject to regulation under 
paragraphs (a)(8) and (c) of this section if the Regional Administrator 
finds that the level of hazardous constituents in the treatment zone 
soil does not exceed the background value of those constituents by an 
amount that is statistically significant when using the test specified 
in paragraph (d)(3) of this section. The owner or operator may submit 
such a demonstration to the Regional Administrator at any time during 
the closure

[[Page 342]]

of post-closure care periods. For the purposes of this paragraph:
    (1) The owner or operator must establish background soil values and 
determine whether there is a statistically significant increase over 
those values for all hazardous constituents specified in the facility 
permit under Sec. 264.271 (b).
    (i) Background soil values may be based on a one-time sampling of a 
background plot having characteristics similar to those of the treatment 
zone.
    (ii) The owner or operator must express background values and values 
for hazardous constituents in the treatment zone in a form necessary for 
the determination of statistically significant increases under paragraph 
(d)(3) of this section.
    (2) In taking samples used in the determination of background and 
treatment zone values, the owner or operator must take samples at a 
sufficient number of sampling points and at appropriate locations and 
depths to yield samples that represent the chemical make-up of soil that 
has not been affected by leakage from the treatment zone and the soil 
within the treatment zone, respectively.
    (3) In determining whether a statistically significant increase has 
occurred, the owner or operator must compare the value of each 
constituent in the treatment zone to the background value for that 
constituent using a statistical procedure that provides reasonable 
confidence that constituent presence in the treatment zone will be 
identified. The owner or operator must use a statistical procedure that:
    (i) Is appropriate for the distribution of the data used to 
establish background values; and
    (ii) Provides a reasonable balance between the probability of 
falsely identifying hazardous constituent presence in the treatment zone 
and the probability of failing to identify real presence in the 
treatment zone.
    (e) The owner or operator is not subject to regulation under Subpart 
F of this chapter if the Regional Administrator finds that the owner or 
operator satisfies paragraph (d) of this section and if unsaturated zone 
monitoring under Sec. 264.278 indicates that hazardous constituents 
have not migrated beyond the treatment zone during the active life of 
the land treatment unit.