Laserfiche WebLink
4 • • <br />inspection that Sylvester Gulch probably followed the toe of the apparent historic slide in this area <br />and would probably do so again after this foundation movement stabilized. <br />MCC respectfully disagrees with the inspection report statement that the stream channel had been <br />"obliterated" or that "irreversibly compromising" damage had occurred to the stream buffer zone <br />or riparian vegetation. The fact is that only very small movement and little perceptible change in <br />the stream channel (within one foot, as described above) had occurred and had not impeded <br />flows. As a precautionary measure and to ensure the protection of the hydrologic balance, MCC <br />requested a field minor revision, but was directed to submit a formal minor revision (which was <br />done so on July 1 lth), to install a flexible pipe in the drainage along the subject fill to eliminate <br />the risk that flows would be impeded in the case of further failure. This minor revision was <br />approved by the Division the following week, but fortunately, was not needed before then (nor <br />since being installed). Very little additional movement has occurred and the stream remains in <br />free-flowing condition. Surface survey data that began on July 12th and continues to date, shows <br />less than 2/10 of a foot movement at any surface location. Per the recommendation of Dr. <br />Pendleton during his inspection, MCC submitted an action plan that was subsequently approved <br />by the Division. In addition to the monitoring and investigations already underway, MCC began <br />cazeful removal of the fill material upon approval of the action plan. <br />No previous geotechnical investigations or mapping indicated that this was an azea of potential <br />instability. Dr. Pendleton and Mr. Solseng noticed other geomorphologic features downstream of <br />the subject failure area that Dr. Pendleton commented would be "easy to miss". As was one of <br />the purposes of the PR 07 commitment to monitor and consider field conditions and experiences, <br />MCC has incorporated further assessment of all fill foundation areas, including an overview of the <br />cleared foundation area as it relates to nearby landforms. The subject fill foundation area was <br />inspected prior to fill placement, and was found to be dry and stable. Surface water was <br />controlled and compaction specifications were consistently met. <br />MCC would also like to clarify that these facilities are being constructed entirely on MCC's <br />property within the upper reaches of Sylvester Gulch. No public lands are being nor have any <br />been damaged. Also, as discussed in NOV CV-97-008 above, redundant drainage and sediment <br />control measures downstream, and within the permit area, have been constructed to protect the <br />hydrologic balance of the ephemeral stream as a whole and prevented impacts within and outside <br />the permit area. <br />MCC respectfully disagrees with the Division's allegation that MCC failed to "adhere to <br />permitting commitments and requirements made in accordance with the Sylvester Gulch Stream <br />Buffer Zone variance approval". The Division approved a variance to the stream buffer zone rule <br />based on the finding that MCC's operations would not impact the stream because the original <br />stream channel would not be disturbed, water quality and quantity would not be adversely <br />affected due to slope stabilization methods (BMPs, revegetation and MSE walls), and the <br />reclamation plan provided for the re-establishment of appropriate riparian vegetation (per Rule <br />4.05.18). As discussed above and in the discussions regarding NOV CV-97-008, the Sylvester <br />Gulch channel was not impacted, water quality and quantity was not adversely affected, and MCC <br />will reclaim the area with vegetation suitable for riparian areas. MCC has adhered to the permit <br />