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Home My WebLink AboutDERR-2025-000117VCP/BROWNFIELDS SECTION – SITE VISIT REPORT SITE NAME: Antimony Mill Site Visit DATE: August 12-14, 2024 PROJECT MANAGER: Leigh Anderson PURPOSE OF VISIT: Observe soil removal, grid sampling, and take split. FIELD OBSERVATIONS: Site is located up a remote canyon near Antimony, Utah and located along Antimony Creek. Chinle shales and Navajo sandstones surrounding the site carry trace arsenic, antimony, and thallium. Mining activity in the canyon fed into a Mill constructed along the south bank of the stream around the time of World War 1. A belt feeder and rails (now removed) carried ore into the Mill from the east where it was then crushed and processed before transport. Ore spills occurred along this belt feeder and over the top of the Mill, as well as the bottom loading area. The top portion of the Mill has begun to destabilize after removal of structural timbers, the other walls and caches are in good condition. At the start of work a stockpile from past removal work remained at the base of the structure, further field screening resulted in needing to remove far more material than expected. A sample grid was established on Tuesday and into Wednesday, and a composite split sample was taken from the western-most grid. Fill material was then brought in to be placed in the excavation, with a plan to re-vegetate the area. Please see page two for retyped field notes. SPLIT SAMPLES COLLECTED? YES NO COMMENTS: Split samples were delivered to the lab on August 15, 2024. IS THE WORK BEING PERFORMED IN A MANNER CONSISTENT WITH THE ACCEPTED WORKPLAN? YES NO COMMENTS: ATTACHMENTS (PHOTOS, MAPS, ETC.) YES NO Antimony August 12 2024 Arrived on-site at noon, prepped at car for fifteen minutes (ice in cooler etc). Park car near the jeep trail turn off to limit track out and notified crew about the RAP stipulations about storms. Met with Brett, rmec, and ihi groups representing different interested parties. Phone numbers: 8013815217 Discussed the high water and storm system that has been cropping up all week, with the plan that around 2 or 3 its best to get out to avoid rainfall heavy enough to wash out the road. Bryce has gotten almost 2 inches in 2 days. Brett isn’t sure that we’ll even be able to deploy the machinery today Also discussed Site History. French method to make bullet add antimony to bullet and fractures. Ww2 not enough reserves to restart the mine and has been defunct since. Walked site and climbed hillside to become familiar with features. Walked up top to look at where belt line feeder entered into top of mill. Also took picture of load out structure, it looks like a vault. Country rock quicklimed back in second level will be higher too just as everything in canyon is Big pit was finishing for the antimony, sorting out for best ore grain, color was olive or hex-chrome colored Last pile in front of bottom wall is remaining waste and next to load out. Met with trucks bringing the equipment at mouth of canyon at about 3 pm after concerns about converging storms pushed us away from the mill before rain could start and wash out the road They will do some fixes to the road though it was passable even for me but some of the ruts and puddles were a bit deep. They need to do it for the equipment anyway. All EP’s left site at 4 pm, the contractors were heading up, also left site 4 pm Antimony August 13 2024 Arrived on site at 9:30 met with Brett with Earthtouch and Jaime from RMEC on the way up and passed two truck loads, tarped etc. main pile at base of mine almost out but found some lighter material Brett thinks is likely to be hot for arsenic around some rotted wood beams buried in the pile. Did two test pits one on east side, surface still had over 400 foot down 200, then 50 at the base. The hot slightly yellow grain material has almost 1400 arsenic and 15,000 antimony Grey material under foundation is clean Having to dig down an additional 2-4 feet to get to floor. Part of the area at the base used to have a wood floor Last of loading started at about 1 pm , (landfill closes at four) once they are loaded and we clean up some areas we will take samples and splits. Darker river bottom fines near large central rock are below detection limit on everything, taking all the way down to that. Unable to get split due to needing to remove more soil from around planned grid layout. Plan on tomorrow first thing. Noticed some suspicious coloration in the side wall, asked to shoot that area, xrf showed nondetect for antimony, arsenic, and thallium, iron because of clay chinle formation oxidized and nonoxidized Left site at 3:30 due to storm warning potentially coming up canyon, though rest of team waited for one more truck load. Passed the truckloads at about 4:21 coming up the road from the landfill and with the time it takes for those trucks from there to the canyon it would be well past six before leaving otherwise. Antimony August 14 2024 Arrived on site about 9:00, passed two more truck loads on the way out. There’s been some groundwater seepage, also going up top again to check if area has been cleared out and fill spread better. Reportedly the storm after DERR left yesterday hit in a major way and hailed on the crew and messed up the forest road and part of the highway on the way out, however the earlier parts of it had dried and was passable by the time DERR personnel arrived. Screening: white flags below action levels, pink or red flags above Splits composited from westernmost grid in pit, along the wall. 20x20 grid with planned 5-6 samples and duplicates and split, split will be of duplicate AC antimony canyon MT mill tailings FL floor OP ore pile residuals Specifically AC-FL-03 sample taken 10:10 composited about 10:30 metals sample put on ice at 11:00am The landfill actually closes at one so last load was 11:00 am. Left at noon Road into canyon, heading east Day 1 Stock pile at base of Mill, facing southwest Day 1 Top of Mill 1, former feeder belt area and ore spill cleanup Day 1 Top of Mill 2, top structure is rotting. Revegetation area below (grey between tan silted creek and forest road), only some plants coming in, planning strategies to address this. Day 1 Top of Mill 3: winter 2023 removal area and gravel fill placed. Day 1 late afternoon storm caused crew to head to mouth of canyon around 3 pm where the crew met with trucks deploying the heavy equipment. Day 2: some of stockpile already removed on arrival. Day 2: Removal of some soil near loading area and vault Day 2: Field screening near loading area and vault. Day 2: Further removal work prompted by field screening. Day2:Gr oundwater seeping around large stone and clean river bottom fines. Day2: Rest of Excavation taken down to dark river bottom cobbles and fines Day 2: Creek state is slightly less silted. No sign of mill contaminant into creek. Day 2: pulling tarp over back of truck as it heads out from site. Day 2: Ominous storm over highway to west, eventually spread to canyon and site Day 3: groundwater seep and rainwater. Excavation at complete depth. Day 3: preparing grid and sampling site Day 3: field screening part of the western grid Day3:Completed 20’x20’ grid for composite sampling. Day 3: compositing samples from western grid location. Took split from this sample. Day 3: Final state of river, silt has settled. Last truck of the day left 11 am due to early closure of landfill, DERR also left at noon.