§ 24.18.040. Development standards and review.

A.

Development on or near a mine hazard area requires the applicant to first demonstrate that no hazards to health or safety exist at the proposed site.

B.

Development within mine hazard areas shall be accompanied by technical studies by qualified professionals that assess the potential risk from mine entries, shafts and ventilation facilities; investigate potential future trough subsidence or sinkhole development due to collapse of abandoned coal mines; and identify specific measures to mitigate the risk in accordance with the criteria below:

1.

Mine entries and shafts shall be permanently sealed using controlled backfill and/or grouting, or an approved, engineered seal and shall include permanent diversion of surface drainage away from the shaft or mine entry; and

2.

Existing sinkholes and shallow prospect excavations shall be backfilled to surface using controlled placement of suitable backfill and shall include permanent diversion of surface drainage away from existing sinkholes and prospect excavations; and

3.

Potential sinkhole hazards shall be assessed by a qualified professional utilizing direct subsurface investigations that demonstrate coal mine workings either do not exist, or that the workings have fully collapsed so that there is no remaining potential for sinkhole development, or show that the hazards associated with any voids that are identified are fully mitigated by backfilling, grouting, or other approved means such that the potential for sinkhole development is eliminated; and

4.

Any coal mine waste dump shall be demonstrated to be stable through analysis by a qualified professional. If the coal mine waste dump does not meet the stability criteria, it shall be regraded or otherwise mitigated to meet stability criteria. If springs or seeps discharge from the coal mine waste dump, materials shall be removed or be covered with a minimum of two feet of clean soil and be revegetated with native vegetation. Development shall not be permitted within one hundred feet of any coal mine waste dump that shows evidence of current or past combustion. Development may be permitted over coal mine waste material only if an investigation and analysis by a qualified professional identifies feasible construction criteria for foundation stability and performance; and

5.

Mine gas hazards shall be mitigated by backfilling all mine entries, shafts and sinkholes and providing appropriate venting; and

6.

Mine fire potential shall be assessed through analysis by a qualified professional. Development shall not be permitted within one hundred feet of mine workings where investigations indicate the possibility of combustion or the possible presence of existing combustion in the underlying seam or seams.

C.

As a result of geotechnical investigations, the director may require special studies to ensure proposed buildings, utilities, and roads are constructed to adequate engineering specifications to address subsidence effects, strains, tilts and other issues associated with mine hazards areas.

(Ord. No. 14773, § 3(Att. B), 7-24-2012)