2.1.1 Narrative
EPA's removal action addresses issues above and below ground and will be carried out in partnership with the Colorado Department of Reclamation and Mining Safety (DRMS) under EPA’s time-critical removal authorities as defined in the 40 CFR 300.
Due to the complexity of the project and the typically short summer construction season, Site work will be sequenced over several years of construction, hence the estimated completion date of October 2016. The following major activities will take place on Site during the 2013 construction season:
- improving Peru Creek Road up to the mine (EPA)
- managing drainage at the portal (EPA)
- consolidating mine waste (EPA)
- underground rehabilitation and investigation (DRMS)
2.1.2 Response Actions to Date
Reporting Period September 1-13, 2014
ERRS remobilized from holiday break and began consolidating waste rock into repository surrounding the Level C portal. A sediment pond was constructed for treatment of the AMD discharge from the portal and a drainage ditch was installed along the haul road discharging into Cinnamon Gulch.
During the early part of September, DRMS’s contractor cleaned the walls and floor space within the bulkhead forms, completed the bulkhead forms and installed grout tubes inside the bulkhead, and installed approximately 400’ of concrete pipeline from the portal entrance to the bulkhead. On September 11, DRMS’s contractor pumped concrete into the bulkhead. DRMS plans concrete sample breaks at 7 days (on or around September 8th), at which time the air side bulkhead forms will be stripped. After a 28 day concrete curing period, DRMS will grout the bulkhead. DRMS plans closure of the valve sometime around October 17th.
Reporting Period August 1-30, 2014
ERRS finished construction of access road to Level A adit and begin consolidating waste rock surrounding the collapsed portal. All waste rock was consolidated into existing slope on the mountain and covered with talus rock from onsite sources. The rock cap was blended into the existing talus fields creating a natural cap. Exploratory excavation was conducted on collapsed mine stopes and any holes encountered were sealed and graded for drainage. The road to Level C adit was improved with drainage controls and road base to improve access for upcoming work. Water treatment and pH monitoring of AMD continued as underground work progressed.
On August 18, with the exception of water treatment, crew put active work at the mine on hold and began excavation and prep work for bridge installation on Montezuma Rd. Crew excavated and removed over 1,200 CYs of what appeared to be mine waste used as fill beneath the road surrounding the former culvert. All mine waste removed from the bridge site was hauled to the Level F repository for disposal. Abutment elevations were confirmed and bedding material was imported and compacted for the foundation of the bridge abutments. Roughly 514 tons of 36” rip rap was imported and placed along each stream bank to armor the bridge foundations. Bridge installation occurred on 8/28 and crew began backfilling around bridge abutments with structural fill and meeting 98% compaction standards. Once areas were backfilled the crew prepped the bridge for asphalt paving and turned the project over to the County.
Reporting Period July 7-31, 2014
ERRS and equipment mobilized on 7/7 and began fixing eroded areas of forest service road washed out during the previous winter. The support zone around Level F portal was prepped and graded to establish space for command posts and equipment staging. The area above Level F adit was graded to push drainage away from the portal. All sediment ponds were cleaned/mucked out and sediment placed into the onsite repository. NaOH solution was delivered and the mine acid discharge water (AMD) treatment system was re-established to treat the AMD from the Level F adit. A new access road was installed through the trees to the Level F adit to provide a more suitable grade for future truck traffic. The former sediment pond by the lower mill building was backfilled with surrounding soils and grade was restored for positive drainage. Consolidation of waste rock around the Level C adit began as well as construction of an access road to the Level A adit.
Reporting Period September 16 - October 19, 2013
1. Penn Mine waste rock pile consolidation and grading
ERRS consolidated the east knob of the waste rock pile into the main waste rock pile, then graded and shaped the pile to a more uniform shape with slightly less slope. The face of the underlying native soils where the waste rock knob was removed was tiered to reduce erosion.
ERRS has completed approximately 10 percent of the erosion control armoring of the tier faces.
2. Waste rock pile swale construction (run on controls)
ERRS has completed construction of the run-on control swale including erosion control rock armoring.
3. Rehabilitation of Level C Adit
DRMS continued rehabilitation of the Level C Adit for the purpose of installing up to two bulkheads (plugs): bulkhead 1 (past the ore body drift) planned for summer 2014; and bulkhead 2 (before the ore body drift) planned for summer 2015. DRMS has completed several steel sets to support unconsolidated material at the interface of the adit entrance culvert (installed last year by DRMS) and the remaining 25 feet or so of overlying unconsolidated material leading up to bedrock. DRMS is currently removing muck (sediments), approximately 1 foot in depth, along a 120 foot reach leading up to the ore body drift. DRMS plans several more steel sets at the ore body drift to address a collapse. From there, DRMS will remove another 120-150 feet of muck (saturated sediments), approximately 2 feet in depth, after which the adit becomes dry for the remaining 400 feet or so that DRMS plans to work in. Because the adit is too narrow for a mucker, DRMS currently plans to remove the muck with a vac truck. DRMS has asked EPA to support this operation by managing the contents of the vac truck at the entrance to the adit.
ERRS backfilled the excavation above the 100 foot culvert entrance to provide positive drainage during the winter.
4. Mine drainage treatment and storage pond operation
ERRS continued throughout the reporting period to treat and buffer large surges of contaminated water coming from the Level C mine adit. DRMS ‘s work is resulting in heavy loads of iron rich sediments being re-suspended and carried out with the mine drainage. The large surge pond (pond #4) is being brought on-line during the day to capture and buffer the significant loads during day operations. ERRS continues to operate the treatment system ahead of the retention ponds which includes adding NaOH and flocculent. ERRS continues to remove sediment from the initial mixing pond on a weekly basis.
5. Forest Service Road 260 repairs
Minor maintenance as needed is ongoing to maintain the service road.
6. Bridge Installation at Peru Crossing
he bridge installation is complete. On September 8, Tom Brunner, HP Geotech, was on-site to conduct bridge approach compaction tests. Tom conducted roller test with the front end loader. He identified a soft spot on the south side of the bridge. ERRS removed soils at this location and hauled in 8-16 inch dredge rock for backfill. Tom observed the backfilling operations and concluded the soft spot was adequately taken care of. ERRS completed welding the abutment and bridge slab metal plates (from underneath) on September 9th. On September 10, Doug Jateico, bridge supplier, brought the guardrail bolts and ERRS installed the guardrails.
7. Borrow pit for armoring rock
ERRS closed borrow operations due to snow.
8. Weather
Weather has been steadily cooling with an occasional inch or two of snow each day. Morning temperatures are in mid-teens with typical warming to between 40-50 degrees by mid-afternoon.
Reporting Period September 9-14, 2013
1. Swale Construction: ERRS completed hauling and stockpiling rock for drainage swale construction on Saturday afternoon (Sept 14). Approximately 35-40 rock loads were loaded with an excavator and hauled down from a rock field located approximately 1/2 mile above the Level C portal. The rock is to be used for construction of the run-on control swale for the waste rock pile and the drainage swale to replace the treatment pond drainage pipe to the first pond.
2. Penn Mine Waste Rock Pile: ERRS brought the grade up outside of the northwest side of waste rock pile in order to prepare for construction of the run-on control swale which will run above the pile, extend down the west side of the pile, and then wrap around the northeast end of the pile. In order to get grade, ERRS pulled back some of the northwest end of the waste rock pile.
ERRS began shaping the waste rock pile which will include consolidation of the east knob into the waste rock pile and reduction of the face slope by extending the toe of the pile out several feet on a bench constructed in front of the existing pile toe.
3. EPA Water Treatment Ponds: ERRS continued to operate the water treatment system during working hours when DRMS was working in the mine. The treatment system received a significant surge of mine water on September 11 when DRMS removed a blockage from the previous day collapse. During this reporting period, 200 gallons of 25% NaOH solution (sodium hydroxide) was used and another tote and 2 drums (410 gallons) were brought for continuing operations. Approximately 100 gallons each of floc and polymer have been used.
ERRS cleaned out the treatment pond on October 12.
4. Repairing of Forest Service Road 260: With the exception of widening the road at the first culvert crossing, ERRS has completed restoration of the forest service road (Peru Creek Road) from Montezuma Road to the Penn Mine.
5. DRMS Work inside Penn Mine: DRMS’s contractor, Harrison Western, has completed spiraling installation work and has begun steel set installation along a 25 foot run of unconsolidated rock. DRMS has installed 3 steel sets at approximately 3-foot intervals. A minor collapse around one of the steel sets occurred on Sept. 10th.
6. Bridge Installation at Peru Crossing: ERRS began stockpiling rip rap material and road base in anticipation of installation of the bridge the first week of October.
7. Weather: The Site has received constant rain events during the reporting period. Soils are becoming saturated along the dirt roads at the Site and require constant maintenance. The surface of waste rock pile is becoming saturated.
Reporting Period August 4 - 18
Road Improvement
- ERRS has improved Peru Creek Road.
Monitoring
- START developed documents to support the collection of pH and XRF measurements. EPA's Environmental Response Team deployed a Viper monitoring network to collect pH measurements in the settling zone. The locations associated with this monitoring effort are described in the attached Site sketch.
- START assessed the quality of the soil in the drainage below the waste piles using XRF technology. EPA's OSC determined that the levels of contamination do not warrant the disturbance to the vegetation that will be caused by their removal. Topsoil will be applied to the area and the drainage will be re-vegetated.
Site Preparation
- ERRS prepared the area around the level F portal for underground activities by diverting the portal's effluent around the waste pile, preparing a pad for the underground team and a staging area for water treatment, and creating a water treatment pit and three settling ponds. These Site preparation activities are described in the following table and the attached Site sketch. A 20' conex box to support water treatment was delivered to the Site on August 16.
| Activity |
Task ID |
Task |
| Site Preparation |
Pad |
Created level pad to support underground activities. |
| Portal |
Diverted effluent from the level F portal into a settling pond. |
| Muck |
Collected muck in a shallow pit which drains towards the waste pile. |
| Treatment |
Created segmented pond to precipitate metals using sodium hydroxide, polymers and flocculant. |
| Staging |
Created a pad and access to support treatment of mine effluent. |
| Diversion |
Diverted water from the settling pit around the waste pile. |
| Settling |
Channeled water through three settling ponds. |
2.1.3 Enforcement Activities, Identity of Potentially Responsible Parties (PRPs)
See the Enforcement Addendum found in the Action Memorandum.
2.1.4 Progress Metrics
To date, approximately 3.0 of 3.8 miles (or ~80%) of Peru Creek Road have been improved. This work has utilized 80 tons of 2" rock and 2,400 tons of road base.
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