Establishing a Groundwater Management Zone
at RCRA Facilities
(October 12, 2001)
35 Ill. Adm. Code Part 620.250 allows for the establishment of
a Groundwater Management Zone (GMZ) within any class of groundwater.
A GMZ is a three-dimensional region containing groundwater being managed
to mitigate impairment caused by the release of contaminants from a site.
Pursuant to 35 Ill. Adm. Code 620.250(b), the GMZ cannot be established
without the Illinois EPA concurrence that the conditions required by
35 Ill. Adm. Code 620.250(a) have been met. Furthermore, the groundwater
management must continue as approved by the Illinois EPA for the GMZ to
remain in effect.
Once it is confirmed that the groundwater corrective action has been completed
and the groundwater quality standards applicable to the class of groundwater have
been achieved the GMZ expires. If concentrations specified in 35 Ill. Adm. Code
620.450(a)(4)(B) will remain in groundwater after completion of the corrective
action, the Illinois EPA will review the adequacy of controls and site
management at least once every five (5) years, based on a written report submitted
to the Illinois EPA.
The Bureau of Land (BOL) has prepared a form for owners or operators to submit
written confirmation that adequate corrective action is being undertaken in a
timely and appropriate manner as required by 35 Ill. Adm. Code 620.250(a)(2).
The form is found in Appendix D of 35 Ill. Adm. Code Part 620. This form and method
of establishing a GMZ does not apply to RCRA closures. This guidance sets forth the
review procedures when establishing a GMZ under an existing corrective action
process in accordance with 35 Ill. Adm. Code 620.250(a)(1) for RCRA closures.
For a GMZ to be established, the groundwater within the proposed GMZ must be
managed to mitigate impairment caused by the release of contaminants from a site.
Source removal actions to prevent additional contamination from reaching groundwater
must occur along with groundwater management. Groundwater management to mitigate
impairment can use various combinations of technology. These include techniques
such as groundwater removal and in-situ treatment. However, any action must
improve the quality of groundwater caused by the release of contaminants from
the site. GMZs can only be approved for areas where groundwater improvement is
If a corrective action to remediate groundwater is approved by the Illinois EPA,
the GMZ can only be approved to the effective limit of the remediation technology.
In some cases in which corrective action is approved, the corrective action may
not deal with all of the groundwater contamination from a site. In such cases
only groundwater undergoing the corrective action process can be included in
the GMZ. For example, if a groundwater pump and treat system has an effective
limit of 300 feet, contamination beyond 300 feet would not be included in
the GMZ. Therefore any exceedences beyond the GMZ would be subject to
enforcement action for violation of 35 Ill. Adm. Code Part 620 and require
additional remediation technologies to address the contamination.
If a GMZ is proposed to extend off-site, two additional considerations must first be met:
- The GMZ can only extend off-site if groundwater off-site is actively undergoing corrective action; and
- The off-site landowner must concur in writing to the establishment of the GMZ.
The off-site landowner concurrence is important because establishment
of the GMZ off-site substantially limits the off-site landowner's ability
to seek compliance with the groundwater standards during the existence of the GMZ.
For the establishment of GMZs on-site, the outer limits of the GMZ should
be restricted to the area where the concentrations of contamination are
equal to or just less than the applicable standards. For small sites,
however, the practicality of establishing GMZs may result in site
boundaries being used.
III. Format to be Utilized for Establishing a GMZ:
A written report must be submitted and will be reviewed by the
Illinois EPA to evaluate the information provided in order to determine
the adequacy of the controls and the management of the GMZ at the site.
The items below must be addressed thoroughly, and if appropriate, the
current information associated with the proposed GMZ discussed. After
review by the Illinois EPA, the Illinois EPA will issue a letter in
regard to the: (1) adequacy of the GMZ; (2) the continued management
of the GMZ; and (3) conditions necessary to ensure that the
requirements of 35 Ill. Adm. Code Part 620 will be met.
The report addressing the GMZ must include, but need not be limited to, the following:
- General information regarding the facility:
- Facility name;
- Facility address;
- County in which facility is located
- Illinois EPA, Bureau of Land, and USEPA Identification Numbers;
- A general description of the type of industry, products manufactured,
raw materials used, location and size of the facility, including SIC
- An identification of specific units (operating or closed) present
at the facility for which the GMZ is proposed;
- A USGS topographic or county map showing the location of the site
and a more detailed scaled map of the facility with each waste management
unit identified in Item 1.f above. Map scale must be specific and the
location of the facility must be provided with respect to Township,
Section, and Range;
- A description of the geology and hydrogeology within the proposed
GMZ and the surrounding area;
- Groundwater classification at the site;
- A description of the circumstances under which the release from
each waste management unit identified in Item 1.f above, to
groundwater was identified.
- Information Regarding the Release, including:
- The chemical constituents released to the groundwater;
- Identification of the chemical constituents detected in groundwater
that are above the applicable standard in 35 Ill. Adm. Code Part 620;
A description of how the site has been investigated to determine the
source or sources of the release;
- A description of how groundwater has been monitored to determine the
rate and extent of the release;
- A description of the groundwater monitoring network and groundwater
sampling protocols in place at the facility;
- The schedule for monitoring of the groundwater; and
A summary of the results of groundwater monitoring associated with
the release at each waste management unit identified in Item 1.f above.
The summary of groundwater results should provide the following
- Dates of sampling;
- Identification of monitoring wells;
- Chemical constituents analyzed and concentrations in parts per
million (ppm) for each monitoring well identified in Item 2.g.ii above;
- Scaled drawings identifying the horizontal and vertical boundaries
of the proposed GMZ.
- Information regarding the approved remedial action including:
- A description of the approved remedial action;
- A description of how the approved remedial action has impacted the release;
- A description of how the approved remedial action is operated and maintained; A projected schedule for completion of remediation;
- An identification of any and all permits obtained from the Illinois EPA
for the remedial action;
- A description of how groundwater at the facility will be monitored
following the future completion of the remedy to ensure that the groundwater
quality standards have been attained;
- A discussion addressing the adequacy of the controls and management of
the proposed GMZ at the site; and
- Course of action for future activities and/or request for
modification in regards to the proposed GMZ at the site.
- Point of Compliance:
In any GMZ, the goal is remediation of the groundwater to the level
of the standards applicable to that class of groundwater. This goal
does not mean all groundwater within the GMZ must be returned to
the groundwater standard. On the other hand, groundwater within
the GMZ that is beyond the point of compliance as established under
35 Ill. Adm. Code Part 620.505(a) is to be remediated to the level
applicable to that groundwater class. However, groundwater
contamination within the three-dimensional zone between the
compliance point wells and the waste management unit could
still exceed the applicable standards at completion of the corrective
action. If this is the case, post-remediation monitoring may be