Section 1784.20  Subsidence Control Plan

a)         Pre-subsidence survey.  Each application must include:

1)         A map of the permit, shadow and adjacent areas at a scale of 1:12,000, or larger if determined necessary by the Department, showing the location and type of structures and renewable resource lands that subsidence may materially damage or for which the value of reasonably foreseeable use may be diminished by subsidence, and showing the location, depth and type of drinking, domestic, and residential water supplies that could be contaminated, diminished, or interrupted by subsidence.

2)         A narrative indicating whether subsidence, if it occurred, could cause material damage to or diminish the value or reasonably foreseeable use of such structures or renewable resource lands or could contaminate, diminish, or interrupt drinking, domestic, or residential water supplies.

b)         Subsidence control plan.  No further information needs to be provided under this Section if the survey conducted under subsection (a) shows that: no structures or drinking, domestic, or residential water supplies or renewable resource lands exist; no material damage or diminution in value or reasonably foreseeable use of such structures or lands would occur; and no contamination, diminution, or interruption of such water supplies would occur as a result of mine subsidence; and if the Department agrees with this conclusion.  If the survey shows that structures, renewable resource lands, or water supplies exist and that subsidence could cause material damage or diminution in value or reasonably foreseeable use, or contamination, diminution, or interruption of protected water supplies, or if the Department determines that damage, diminution in value or foreseeable use, or contamination, diminution, or interruption could occur, the application must include a subsidence control plan that contains the following information:

1)         A description of the method of coal removal, such as longwall mining, room-and-pillar removal or hydraulic mining, including the size, sequence and timing of the development of underground workings;

2)         A map of the underground workings that describes the location and extent of the areas in which planned-subsidence mining methods will be used and that identifies all areas where the measures described in subsections (b)(4), (b)(5) and (b)(8)(A) will be taken to prevent or minimize subsidence and subsidence-related damage and, when applicable, to correct subsidence-related material damage;

3)         A description of the physical conditions, such as depth of cover, seam thickness, lithology of overlaying and underlying strata, and geotechnical stability parameters that affect the likelihood of subsidence and subsidence related damage or potential underground mining impacts on ground water supplies;

4)         A description of the monitoring, if any, needed to determine the commencement and degree of subsidence so that, when appropriate, other measures can be taken to prevent, reduce or correct material damage in accordance with 62 Ill. Adm. Code 1817.121(c);

5)         Except for those areas where planned subsidence is projected to be used, a detailed description of the subsidence control measures that will be taken to prevent or minimize subsidence and subsidence related damage, such as, but not limited to:

A)        Backstowing or backfilling of voids;

B)        Leaving support pillars of coal;

C)        Leaving areas in which no coal is removed, including a description of the overlying area to be protected by leaving coal in place;

D)        Taking measures on the surface to prevent or minimize material damage or diminution in value of the surface; and

E)        Geotechnical and engineering analysis of the mining geology and geometry, percent extraction and historic performance to substantiate a stable subsidence control plan;

6)         A description of the anticipated effects of planned subsidence, if any;

7)         For those areas where unplanned subsidence is projected to be used, a description of procedures to determine the quantity and quality of drinking, domestic and residential water supplies in accordance with 62 Ill. Adm. Code 1817.121(a)(2), if impacts could reasonably be expected to cause material damage.  The applicant may request an exemption from conducting surveys of drinking, domestic and residential water supplies required at 62 Ill. Adm. Code 1817.121(a)(2) if it can be demonstrated that material damage resulting from underground mining is not likely to occur.  This demonstration shall be based on site specific geotechnical information, stability design and historical performance provided in subsection (b)(3) and (b)(5);

8)         For those areas where planned subsidence is projected to be used, provide:

A)        a description of methods to be employed to minimize damage from planned subsidence to structures and facilities; or the written consent of the owner of the structure or facility that minimization measures not be taken; or, unless the anticipated damage would constitute a threat to health or safety, a demonstration that the costs of minimizing damage exceed the anticipated costs of repair;

B)        a description of procedures to determine the condition of structures and facilities and the quantity and quality of drinking, domestic and residential water supplies in accordance with 62 Ill. Adm. Code 1817.121(a)(2), if impacts could reasonably be expected to cause material damage.  The applicant may request an exemption from conducting structure condition surveys and/or surveys of drinking, domestic and residential water supplies required by 62 Ill. Adm. Code 1817.121(a)(2) if it can be demonstrated that material damage resulting from underground mining is not likely to occur.  This demonstration shall be based on site specific geotechnical information, stability design and historical performance provided under subsections (b)(3) and (b)(6);

9)         A description of the measures to be taken in accordance with 62 Ill. Adm. Code 1817.41(j) and 1817.121(c) to replace adversely affected protected water supplies or to mitigate or remedy any subsidence related material damage to the land and protected structures.  In conjunction with this requirement, the applicant shall:

A)        provide procedures to determine the existence and degree of material damage or diminution of value or foreseeable use of the surface, structures and facilities, or water quality and quantity.  The procedures shall also address resolution of disputes between the landowner and the permittee over the existence, amount, level or degree of damage, such as third party arbitration; and

B)        provide a plan for determining an appropriate present worth amount and describe how to resolve disputes between the landowner and the applicant over this amount, such as third party arbitration;

10)       Other information specified by the Department as necessary to demonstrate that the operation will be conducted in accordance with 62 Ill. Adm. Code 1817.121.

(Source:  Amended at 24 Ill. Reg. 5998, effective March 21, 2000)