INSPEC44090 - Laserfiche WebLink

Home Browse Search

(Page 2) MINE ID # OR PROSPECTING ID # M-1976-020 INSPECTION DATE 4/10/03 INSPECTOR'S INITIALS RCO ' OBSERVATIONS This partial inspection was performed by the Division as part of its monitoring of Construction Materials 112c in-stream permits. The operator's representative was contacted about the inspection, and a time was arranged to meet at the site. The operator named on page one was present throughout the inspection. The required permit ID sign was noted at the entrance gate to the site, but boundary markers were not inspected, due to the limited portion of the interior of the site that was the area of interest during this inspection (area of amendment AM-011. The gap in the upstream end of the intact portion of the old ACOE dike was recently closed with a low berm of placed fill, directing the river flow to the main channel on the east. The present low water level allowed the bank stabilization work to proceed. It is not clear yet whether the ACOE will allow this upstream end of the side channel to be permanently closed. Excavation of the pit to the west of the river, on alluvial material has not been started. Preliminary steps to stabilize the west bank against erosion were underway at the time of the inspection, and are required to be finished prior to commencement of excavation of the future pit. These steps include installation of a jetty upstream of the bank adjacent to the pit, and the armoring of the west bank, starting at the jetty and extending downstream for a distance of 480 feet. The jetty appears to be largely complete, though the structure and its components were not measured nor certified during this inspection. Its upstream end is keyed into the west bank, it is composed of large rock (whose average diameter may be close to 5 feet), and is about 120 feet long. Fill material has been placed behind the upstream end of the jetty, to the height of the top of the jetty. Discharge from the upslope pond discharge pipe was entering the unfilled area behind the jetty, though that may be a temporary condition. Additional fill material or pipe installation or armoring in this area may yet be installed. Placement of the upstream berm acted to keep the water level very low in the secondary channel where the structural work on the bank was being carried out. Installation of the bank riprapping was underway. The bank was graded to a uniform 2:1 slope by excavator. The approved riprap design consists of cast concrete blocks, 4' x 4' x 3' in size, placed in two rows, with blocks within each row 2 feet apart, and the 2 rows spaced 2 feet apart on the graded slope. Embedded rebar in the sides of the blocks allowed for the blocks to be cabled together. The downstream half of the lower row of blocks was in place, their lower edge at the low water line. The blocks were buttressed in place by pulling up cobbles below them. After cabling, the spaces between the blocks would be filled with pitrun, capped with soil, and planted with willow stubs, according to the operator. As work progresses, structures should be checked for compliance with the plan. There were no additional items observed or discussed. No problems exist at this time. All responses or questions about this inspection report should be directed to this inspector at the Division's Durango Field Office. The address is: Division of Minerals and Geology, 701 Camino del Rio, Room 125, Durango, Colorado 81301; telephone 970/247-5193, or fax 970/247-5104. I & E Contact Address ec: Harry Posey, DMG ^ CE NAME OPERATOR STREET CITY/STATE/ZIP Marcia Talvitie Four Corners Materials. Inc. P.O. Box 2707 Durango, CO 81301 ^ BL ^ FS ^ HW ^ HMWMD (CHI ^ SE ^ WOCD (CHI ^ OTHER I, Bob Oswald, certify that on the signature date shown on page one, I deposited a true and complete copy of this entire inspection report in the United States mail, first class postage paid, to the operator of record for this site at the address indicated, and to those others designated in this report to receive copies (DMG personnel exceptedl. Signature ~ ~~