[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: 40CFR257.22]



[Page 384-385]

 

                   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.  257.22  Ground-water monitoring systems.



    (a) A ground-water monitoring system must be installed that consists 

of a sufficient number of wells, installed at appropriate locations and 

depths, to yield ground-water samples from the uppermost aquifer (as 

defined in Sec.  257.5(b)) that:

    (1) Represent the quality of background ground water that has not 

been affected by leakage from a unit. A determination of background 

quality may include sampling of wells that are not hydraulically 

upgradient of the waste management area where:

    (i) Hydrogeologic conditions do not allow the owner or operator to 

determine what wells are hydraulically upgradient; or

    (ii) Sampling at other wells will provide an indication of 

background ground-water quality that is as representative or more 

representative than that provided by the upgradient wells; and

    (2) Represent the quality of ground water passing the relevant point 

of compliance specified by the Director of an approved State or at the 

waste management unit boundary in an unapproved State. The downgradient 

monitoring system must be installed at the relevant point of compliance 

specified by the Director of an approved State or at the waste 

management unit boundary in an unapproved State that ensures detection 

of ground-water contamination in the uppermost aquifer. The relevant 

point of compliance specified by the Director of an approved State shall 

be no more than 150 meters from the waste management unit boundary and 

shall be located on land owned by the owner of the facility. In 

determining the relevant point of compliance the State Director shall 

consider at least the following factors: the hydrogeologic 

characteristics of the unit and surrounding land, the volume and 

physical and chemical characteristics of the leachate, the quantity, 

quality and direction of flow of ground water, the proximity and 

withdrawal rate of the ground-water users, the availability of 

alternative drinking water supplies, the existing quality of the ground 

water, including other sources of contamination and their cumulative 

impacts on the ground water, and whether the ground water is currently 

used or reasonably expected to be used for drinking water, public 

health, safety, and welfare effects, and practicable capability of the 

owner or operator. When physical obstacles preclude installation of 

ground-water monitoring wells at the relevant point of compliance at 

existing units, the down-gradient monitoring system may be installed at 

the closest practicable distance hydraulically down-gradient from the 

relevant point of compliance



[[Page 385]]



specified by the Director of an approved State that ensures detection of 

groundwater contamination in the uppermost aquifer.

    (b) The Director of an approved State may approve a multi-unit 

ground-water monitoring system instead of separate ground-water 

monitoring systems for each unit when the facility has several units, 

provided the multi-unit ground-water monitoring system meets the 

requirement of Sec.  257.22(a) and will be as protective of human health 

and the environment as individual monitoring systems for each unit, 

based on the following factors:

    (1) Number, spacing, and orientation of the units;

    (2) Hydrogeologic setting;

    (3) Site history;

    (4) Engineering design of the units; and

    (5) Type of waste accepted at the units.

    (c) Monitoring wells must be cased in a manner that maintains the 

integrity of the monitoring well bore hole. This casing must be screened 

or perforated and packed with gravel or sand, where necessary, to enable 

collection of ground-water samples. The annular space (i.e., the space 

between the bore hole and well casing) above the sampling depth must be 

sealed to prevent contamination of samples and the ground water.

    (1) The owner or operator must notify the State Director that the 

design, installation, development, and decommission of any monitoring 

wells, piezometers and other measurement, sampling, and analytical 

devices documentation has been placed in the operating record; and

    (2) The monitoring wells, piezometers, and other measurement, 

sampling, and analytical devices must be operated and maintained so that 

they perform to design specifications throughout the life of the 

monitoring program.

    (d) The number, spacing, and depths of monitoring systems shall be:

    (1) Determined based upon site-specific technical information that 

must include thorough characterization of:

    (i) Aquifer thickness, ground-water flow rate, ground-water flow 

direction including seasonal and temporal fluctuations in ground-water 

flow; and

    (ii) Saturated and unsaturated geologic units and fill materials 

overlying the uppermost aquifer, materials comprising the uppermost 

aquifer, and materials comprising the confining unit defining the lower 

boundary of the uppermost aquifer; including, but not limited to: 

thicknesses, stratigraphy, lithology, hydraulic conductivities, 

porosities and effective porosities.

    (2) Certified by a qualified ground-water scientist or approved by 

the Director of an approved State. Within 14 days of this certification, 

the owner or operator must notify the State Director that the 

certification has been placed in the operating record.