Thursday, June 19, 2008:
U.S. Environmental Protection Agency (EPA) On-Scene Coordinator (OSC) Dan Heister was notified by Ken Aitken of the Oregon Department of Environmental Quality (ODEQ) that the adit drainage diversion system at the Formosa Mine near Riddle, Oregon had developed a leak. The leak was noted during the June 9, 2008 site meeting at the Formosa Mine led by Remedial Project Manager (RPM) Denise Baker of EPA. The leak was located in the drain pipe on the west (down hill) side of the U.S. Bureau of Land Management (BLM) access road near the northern-most section of the pipe, such that the released water was flowing overland toward the headwaters of Middle Creek.
OSC Heister informed Chris Field of EPA of the adit diversion system leak near the Middle Creek headwaters. EPA decided to that it was necessary to repair the leak to the adit diversion system as soon as possible in order to abate the mine drainage flow directly toward Middle Creek and restore the system such that flow would be directed to the outfall located approximately 600 feet south of Middle Creek. In addition, the 12-inch elbows in the Adit diversion system pipe located near the Formosa adit, between the water aeration cascade section and the concrete weir vaults would be replaced with alternate piping to reduce the sediment clogging potential.
OSC Heister contacted John Barber of BLM to inform him of the leak and the needed repairs. Mr. Barber suggested that BLM might be able to mobilize their environmental contractor to complete the repairs. OSC Heister asked Mr. Barber to inform him by Friday, June 20, 2008 whether BLM could contract the work.
Friday, June 20, 2008:
Mr. Barber informed OSC Heister that the soonest he likely could get BLM’s contractor mobilized to the Formosa Mine would be week of June 30, 2008 or later. In order to accomplish the work more quickly, EPA decided to conduct the work with the support of START and ERRS contractors the week of June 23, 2008.
START Team Member (STM) Jim Petersen was notified by OSC Heister that STM Petersen, OSC Heister, and an ERRS crew would mobilize to the Formosa Mine the following week and begin the repair work Tuesday, June 24, 2008.
Monday, June 23, 2008:
OSC Heister, START, and ERRS traveled to Canyonville, Oregon in preparation for the Formosa Mine adit diversion system repair.
Tuesday, June 24, 2008:
OSC Heister, STM Petersen, and ERRS crew met at 07:00 in Canyonville, Oregon to discuss objective, logistics, safety concerns, and schedule of the adit diversion repair project. The ERRS crew included project manager (EPM) Bryan Chernick and four laborers/equipment operators. A tailgate safety meeting was conducted. The ERRS resources included an excavator, four pickup trucks, an equipment trailer, a 500-gallon water trailer with pump and hoses, and a semi-truck with a flatbed trailer (carrying one of the trucks and the excavator).
The objective for the response was to repair the adit diversion system to reduce the potential for a mine drainage release water into Middle Creek during the interim period until the diversion system is replaced (estimated to be late-summer 2009). Specific items included:
• Repair the major leak identified on June 9, 2008 site visit.
• Locate and repair other leaks along the pipeline route.
• Modify the existing pipe to alleviate the clogging problem at the tight bend in the 12-inch pipe between the tiered cascade section and the concrete vaults.
• As practicable, identify and repair other potential sources of release from the diversion system.
At 07:30 EPA, START, and ERRS began driving to the Formosa Mine. The semi-truck and excavator were staged at the intersection of Shoestring Road and BLM road 31-6-35.0. ERRS evaluated the gravel BLM road to the mine, and decided that at least two of the sharp turns along the route were too tight for the semi-truck and trailer to negotiate. ERRS staged the semi-truck at the Shoestring Road intersection, and an operator drove the excavator the remaining 6.7 miles to the Formosa Mine site.
At approximately 08:30, OSC Heister, STM Petersen, and ERRS PM and remaining crew arrived on site. The two operators driving the excavator to the site would arrive approximately four hours later. While waiting for the excavator to reach the site, the site conditions were evaluated. The total flow from the adit diversion system was approximately nine gallons per minute. All of the flow originated from the Formosa Adit. There was no flow from the Silver Butte drain. (Eric Henan, a BLM Mine Specialist from the Roseburg District Office familiar with Formosa Mine, had previously indicated to OSC Heister and STM Petersen that the Silver Butte adit normally did not discharge water even during the winter and spring seasons, and had only been observed flowing on one occasion during an extremely high runoff event.)
The total amount of the flow in the adit diversion system was leaking from a crack in the 12-inch HDPE pipe approximately 40 feet south of the buried portion of the pipe beneath the BLM road. This location was near the northern-most extent of the adit diversion system, and closest to the Middle Creek headwaters. The water was draining along the surface down the slope for approximately 50 feet, at which point all of the flow had drained into the subsurface.
Rusty staining and rutting was observed on the BLM road originating at the Formosa Adit and continuing north along the road for several hundred feet from previous adit drain upsets. During a May 1, 2008 site visit OSC Heister, STM Petersen, and an ERRS member observed such a condition resulting from a sediment blockage of the pipe in elbow below the cascade tiers. At that time the OSC, STM, and ERRS removed the blockage by forcing a smaller diameter pipe through the sediment clog, clearing the leak.
ERRS began the repair work by diverting the adit flow to a 6-inch drain line that was part of a previous adit drain system. The 6-inch drain line is located parallel, and approximately 100 feet upslope, of the current pipe. The discharge point of the 6-inch drain line on the Formosa Explorations, Inc. property upslope of the current system discharge point.
ERRS removed the 12-inch HDPE pipe from the diversion system between the lower-most tier of the cascade tiers and the open channeled portion of the system upstream of the concrete vaults. This section redirected the flow from a westerly flow direction to a northeasterly direction and contained a 12-inch 90o elbow and a 45o elbow. A large volume of sediment was observed inside the removed pipe. ERRS reconstructed the segment using 24-inch HDPE pipe. The new 24-inch diameter 90o and 45o elbows are expected to be far less prone to clogging. ERRS cleared sediment from the cascade tier and the open-channeled pipe segment immediately upstream and downstream of the replaced portion of the pipe. ERRS used the excavator to place bedding material beneath and around the pipe securing it in position.
STM Petersen and two ERRS members walked the length of the adit diversion pipe to identify other leak points. Two openings in the 12-inch pipe were noted, a cracked coupler located approximately 200 feet upstream of the outlet, and a pipe segment that had shifted and was offset at approximately 100 feet upstream of the outlet.
At 17:30, after securing equipment, ERRS, START, and EPA left the site.
Wednesday, June 25, 2008:
At 07:00 EPA, START, and ERRS met in Canyonville, Oregon to discuss the day’s work objectives and safety issues, then proceeded to the Formosa Mine. One ERRS member drove to Roseburg, Oregon to obtain supplies.
At 08:00 ERRS members used hand tools to dig out the drainage trenches at the Formosa Adit, upstream of the catchment basin, to reduce potential for adit drainage to flow away from the catchment basin and diversion system during high water flow events. ERRS used the excavator finish placing soil around the 24-inch pipe placed the previous day and to smooth and grade the soil bank above the road that had been disturbed during the pipe placement.
At 10:00 ERRS began repairing the leak in the pipe located on the steep embankment below the BLM road on the northern portion of the pipe system. The pipes upstream and downstream of the broken coupler were cut, and replaced with a new segment of pipe attached with band couplers to the adjoining pipe segments. A 45o elbow and approximately 40 additional feet of pipe were also replaced in this section of the pipe system in order to line up the new and old sections of pipe, and to reduce the rises and dips along the pipe where sediment would tend to build up and clog the pipe. Six additional steel fence posts were installed to support the pipe.
The cracked coupler located approximately 200 feet upstream of the outlet was cut away and replaced with a new 2-foot segment of pipe band-coupled into place. The offset pipe segment located approximately 100 feet upstream of the outlet was removed and replaced with a new 20-foot segment.
At 13:30 the flow was restored to the adit diversion piping system, and the repairs tested by surging the pipe with 500 gallons of water in ERRS water tank and also by removing the sediment from the top of the weirs in the concrete vaults (releasing an additional 300 to 400 gallons). STM Petersen walked the lower portion of the pipe during the surge to check the two downstream repairs and to identify other possible leaks. A leak was observed in the 45o elbow replace earlier in the day. This leak was repaired by installing new couplers. The two downstream repairs held water, and no other leaks were identified.
Upstream of the upper concrete vault ERRS replaced approximately 40 feet of pipe heavily choked with sediment and with cracked couplings. Steel posts were installed to secure this new pipe segment. As a final measure, in the section of pipe located immediately downstream of the new 24-inch pipe, a slot was cut into the 12-inch pipe with the intent that in the event of a clog in that portion of the system, overland flow could re-enter the pipe.
Flow was restored to the adit diversion system. A 500 gallon water surge from the water tank was pumped into the system. No leaks were observed. ERRS cleaned up the site, placed the removed sections of HDPE pipe and fittings in a location east of the BLM road behind the concrete vaults, then demobilized from the site. OSC Heister and STM Petersen left the site at 15:00.
Thursday, June 26, 2008:
STM Petersen drove to the site arriving at 08:30 for a final adit diversion system check of the portions visible from the BLM road. No leaks were observed. STM Petersen left the site at 09:00 and returned to Portland.
Wednesday, August 13, 2008:
STM Petersen drove to the site arriving at 12:30 for a final adit diversion system check of the portions visible from the BLM road. No leaks were observed. STM Petersen left the site at 14:00.
