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 occurring.
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 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.
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: