INSPEC06600 - Laserfiche WebLink

Home Browse Search

• (Page 21 • MINE ID N OR PROSPECTING ID ay M-1995-036 INSPECTION DATE 3/14/01 INSPECTOR'S INITIALS RCO OBSERVATIONS This inspection was performed by the Division as part of its monitoring of Construction Materials 112c permits. The operator was contacted about the inspection and a time was arranged to jointly inspect the site. The operator named on page one was present throughout the inspection. The mine identification sign and affected area boundary markers are in place and in compliance with Rule 3.1.12. The permit area is actually divided into two parcels, separated by the DOW access road to the Walker Wildlife Area. The access road is not included in the permit, and is shown on the 1995 application maps as a 60-foot road corridor, with non-mining setbacks of an additional 30 feet on both sides of this road. It appears that fill material has been imported to the site for use as structural fill. DMG records indicate that the approved mining and reclamation plans allow for placement of backfill. This site is being excavated with all raw materials being exported for processing. The site is adjacent to another permitted site IM-1991-1361, upon which the processing occurs. The onsite overburden, plus reject material from the adjacent processing site, are sources for the materials which are imported and dumped here as permanent structural fill. There is also some dumoina of imported concrete rubble along a part of the southwest hiohwall. The file does not indicate that this practice is in compliance with the approved plan. The concrete fill material has been imported to the site for use as structural fill. DMG records do not indicate that the notice specified in Rule 3.1.5 191 has been submitted for this backfill importation and placement. Please submit this notice by the correction date specified on the last pane of this report. Please note that the Notice to allow importation of rubble may constitute a technical revision, which carries a S188 fee. The final reclamation plan includes leaving a lake on the southwest half of the site, and filling the northeast half of the site to the original grade (matching the surrounding grade of unmined landl. The aggregate is removed down to the underlying shale layer. The depth of the pit is about 20 feet or less, and the "normal water table level" (according to the 1995 application) is about 12 feet below original grade. The pit is dewatered as needed during operations. The mining has progressed to very near the northwest end of the permit area. The operator must ensure that the 60-foot DOW road is marked, as well as the 30-foot setbacks which are not to be mined. Disturbance includes stripping brush and vegetation, stripping topsoil and overburden to be stockpiled, and excavation. It is not clear whether the 6 or more acres comprising the smaller parcel of separated permitted land on the northwest end, will be mined at all. There is no disturbance there yet. (Note: reclaimed slopes in this smaller parcel are to be 10:1 gradient.) The pit highwalls are mined as vertical, with later backfilling bringing the slopes to gentler gradients. Significant fill has been placed along the eastern end of the northeast boundary, in accordance with the approved plan. The eastern end of the southwest boundary has been graded to a slope somewhat gentler than 1:1. Most of the western highwalls are fairly vertical. There were several piles of pitrun in the pit, as well as a pile of manufactured gravel/waste asphalt product, which was being removed. The operator should note that the approved reclamation plan calls for final 3:1 slopes, to be topsoiled and revegetated in all areas above high water level. None of the slopes are at 3:1 yet, though recent annual reports note that some slopes are fully graded. This must be closely examined by the operator, so that it is accurately reported, but also to prevent the premature use of topsoil or application of seed to an unfinished slope. No revegetation is currently underway. A small portion of asphalt pavement was noted at the top of the SW highwall toward the western limit of the pit. Review of the file reveals that a paved 44-foot wide drainage control Swale formerly crossed the site, conveying drainage runoff from Raihead Avenue to the river. The asphalt observed appears to be a remnant of that Swale. Directly across the pit on the opposite highwall is a small erosion feature, which appears to be the location of the current runoff from Railhead Avenue. A stipulated condition of the permit issuance was that the operator provide an engineered design for a replacement drainage structure, to be reviewed by the Division, and then made part of the reclamation plan. The operator must ensure that these structures have been designed, and that they are eventually installed as part of the final reclaimed pit. These structures' locations are shown on the reclamation plan map.