| Action Date |
Action |
Description |
DEC Staff |
| 8/26/1993 |
Site Added to Database |
Elevated levels of lead, zinc, arsenic and mercury are present at the site. |
Former Staff |
| 11/10/1994 |
Site Ranked Using the AHRM |
Initial ranking. |
Former Staff |
| 11/1/1999 |
Site Ranked Using the AHRM |
Re-ranked. Changed Air Exposure index from 0.2 to 1.0; Release Information Value from 0.2 to 1.0; and Quantity Value to 2.1. The unknown quantity value is based on the elevated arsenic levels at the cyanide tailings area. Volume or areal extent unknown. |
Bill Janes |
| 11/12/1999 |
Site Ranked Using the AHRM |
Re-ranked. Changed the Value for Environmental/Recreation Area from 0 to 3 based on the fact that the entire complex is probably about a mile long. At one end is the Sandy Beach recreation area, a City park. Sandy Beach is comprised of old Treadwell mine tailings. At the other end is the cyanide mill tailings area. Obvious stress to vegetation because no vegetation is growing there. |
Former Staff |
| 1/18/2001 |
Update or Other Action |
CERCLIS ID # AKD981767387. History: state-lead Discovery 3/1/87, PA 6/23/89, SI 6/30/91. Site Reassessment federal lead 6/30/99 thru 9/18/00. |
Bruce Wanstall |
| 2/15/2002 |
Update or Other Action |
Project tickler update - Reviewed SI data. Conferred with Stephanie regarding potential health risks. Sent email to Carnahan recommending that we move on further investigation and probable cleanup. |
Bill Janes |
| 12/15/2003 |
Site Ranked Using the AHRM |
GW values changed to minimals. GW not used in the area. |
Bill Janes |
| 6/6/2005 |
GIS Position Updated |
GIS data transferred from Garmin GPS 76 calibrated for NAD 27. Accuracy estimate is high. Glory Hole adit lat long coordinates projected on Topozone map 1:50K and saved to electronic file at \\Jn-svrfile\groups\SPAR\Spar-Contaminated Sites\38 Case Files (Contaminated Sites)\1538 Douglas\1538.38.001 Treadwell Mine Complex |
Bruce Wanstall |
| 1/3/2006 |
Meeting or Teleconference Held |
Janes and Wanstall met with a permitee representative and CBJ Planning Commission to discuss interim control measures at the lower cyanide tailings area to allow a closely supervised increase in recreational activity in 2006 and design of Site Characterization Plan to support development of permanent remedial alternatives. |
Bruce Wanstall |
| 4/20/2006 |
Meeting or Teleconference Held |
ADEC met with the landowner AJT Mining Properties representative David Stone and legal representation Steve Sorensen of Simpson Tillinghast & Sorensen to coordinate a Site Characterization and Corrective Action Plan for the lower cyanide waste rock site at the Mexican Mine in the Treadwell Mine Complex. The cost recovery process and site closure with property restrictions were explained by ADEC. |
Bruce Wanstall |
| 6/20/2006 |
Update or Other Action |
Discussion was held by telephone with Smith Bayliss LeResche about the mine tailings pile site conditions, the sampling plan and the condition of a stream that passes near the upper tailings pile. |
Bruce Wanstall |
| 6/28/2006 |
Update or Other Action |
Treadwell MIne Cyanide Tailings Site Investigation Plan recieved; site visit and plan review scheduled in July 2006. |
Bruce Wanstall |
| 7/10/2006 |
Proposed Plan |
Site Investigation and Tailings Stabilization Workplan approved with comments and requests. |
Bruce Wanstall |
| 10/5/2006 |
Site Characterization Report Approved |
Investigation and laboratory Report reviewed and approved. |
Bruce Wanstall |
| 12/13/2006 |
Update or Other Action |
ADEC sent a letter reminding the responsible party of their agreement to install a cap and re-vegetate the Mexican MIne contaminated site portion of the Treadwell Mine Complex. Site characterization of the lower tailings pile in 2006 by the AJT Mining Properties’ environmental consultant established that mercury in the waste rock exceeded the 18 AAC 75.341 Soil Cleanup Level Table B1 soil screening level for the migration to groundwater pathway. Statute and regulatory authority to cost recover expenses incurred by the ADEC was also stated. |
Bruce Wanstall |
| 1/5/2007 |
Update or Other Action |
AJT Mining Properties has declined to accept responsibility for $1171.40 in costs ADEC incurred preparing for and meeting with the City and Borough of Juneau Planning Commission to assist in the permitting process for development of the former Mexican Mine cyanide waste rock site on Douglas Island. The CBJ permit was approved contingent upon AJT Mining Properties coordinating with ADEC to conduct a site investigation and develop a plan for remediation of the contaminated property. AJT accepted responsibility for ADEC project management costs beginning with a meeting held at the ADEC on April 20, 2006 to discuss the project. On 1/5/2007, a check for $547.58 was received by DOL for ADEC costs to date. |
Bruce Wanstall |
| 9/27/2007 |
Exposure Tracking Model Ranking |
Although a formal determination for site control has not been made concerning its use, surface water and ground water on the property are not used, are unlikely to become used, and do not contribute to a source of drinking water in the area. Surface water drainage has been diverted away from the upper tailings pile to control leaching from the iron sulfide mineral known as pyrite (FeS2). The lower tailings pile is near tidewater at Gastineau Channel. Neither water body presents an unacceptable exposure risk via the ingestion pathway. |
Bruce Wanstall |
| 10/17/2007 |
Meeting or Teleconference Held |
DEC and Nortech held a meeting at the lower tailings cap site; that area was almost entirely vegetated. The upper tailings pile will need some repairs to the cap that was installed by the State (DNR) in the 1990s. In general, it appears the site controls are effective in controlling the dermal exposure route. Tentative approval of the vegetated cover site remedy was verbally given along with a request that a binding long term maintenance and inspection agreement be submitted by landowner AJT Mining Properties Inc. |
Bruce Wanstall |
| 12/5/2007 |
Document, Report, or Work plan Review - other |
Review the Treadwell Mine Cyanide Tailings Stabilization Cap Report dated 11/15/07; the summary document is attached. DEC approval letter for the site remedy long term maintenance plan was sent to AJT Mining Properties; the document is attached to the database record. |
Bruce Wanstall |
| 12/7/2007 |
Long Term Monitoring Established |
ADEC has determined that the soil cap and surface drainage long term maintenance plan on the upper and lower tailings sites provides an effective site control remedy. Site remedy control ensures that residual soil contamination does not pose an unacceptable risk to human health and the environment.
Should any areas within the lower tailings stabilization cap or the upper tailings area show damage to the vegetation within the tailings area or damage to the stabilization caps, the date of inspection, date of damage and actions taken to repair and prevent further damage shall be logged and made available to the ADEC. ADEC requests notification of plans to repair, modify, or expand the cap areas. Stormwater drainage ditches and culverts shall be maintained in such a manner that does not cause erosion within the tailings areas. |
Bruce Wanstall |
| 1/10/2008 |
Institutional Control Record Established |
Institutional controls limit, prohibit or protect against activities that interfere with improvements designed to encapsulate or control residual contamintion per 18 AAC 75.990(54).
There is residual soil contamination remaining at depth beneath the soil cover at the upper and lower tailings piles on the Treadwell Mine Complex. ADEC determined it does not pose an unacceptable risk to human health or the environment, subject to the following conditions: Any proposal to excavate the residual contaminated material shall be reported to ADEC and a work plan describing how the soil will be managed and/or disposed must be submitted for review and approval prior to excavation. Any proposal to transport soil and/or groundwater off site requires ADEC approval in accordance with 18 AAC 75.325(i). |
Bruce Wanstall |
| 1/11/2008 |
Conditional Closure Approved |
The Treadwell Mine Complex shall be managed in accordance with the approved inspection and maintenance plan (prepared by Nortech and dated November 2007). Site inspections of the soil cap areas shall be conducted two times per year to ensure that site conditions remain stable. In the event the tailings pile areas are damaged or disturbed, ADEC shall be notified and a corrective action plan submitted for review and approval.
This determination is in accordance with 18 AAC 75.380(d)(2) and does not preclude ADEC from requiring additional assessment and/or cleanup action if future information indicates that this site may pose an unacceptable risk to human health or the environment.
Site Closure (without conditions) can be achieved when soil sampling confirms that all soil meets the most stringent 18 AAC 75.341 Migration to Groundwater, Over 40 Inch cleanup levels and ground water meets 18 AAC 75.345 Table C levels.
|
Bruce Wanstall |
| 12/1/2008 |
Site Visit |
ADEC traveled to the site with Jason Ginter (Nortech) and inspected the upper and lower tailings sites. Observations determined that maintenance of the ADEC-approved site control remedy is necessary in 2009 before resumption of Alaska Canopy Adventures business activity on the property. While the lower tailings cap appears intact and requires only minor drainage maintenance along the southern edge and spot repair along the beach, the upper tailings pile requires more extensive water management and surface cap repairs. The main access road passes alongside the upper tailings area and the former vegetation on the cap has been severely damaged. Surface water flowing onto the bare material is washing out channels in the tailings. Controls must be installed to divert surface water from entering the tailings pile. |
Bruce Wanstall |
| 1/5/2009 |
Update or Other Action |
ADEC requests that a lined roadside drainage be installed between the road and the upper tailings pile with abutments that will prohibit any vehicles from entering the stabilization cap clearing. Top soil will be placed over the upper tailings pile and seeded to restore vegetation. If a vehicle pullout is needed for traffic then another location will have to be cleared for that purpose. |
Bruce Wanstall |
| 5/13/2009 |
Site Visit |
ADEC accompanied the landowner to inspect repairs to the cap and improved water management system installed in spring 2009 at the upper cyanide tailings pile. The 2008 annual inspection found damage to the cap from vehicular activity related to the popular zip line recreational business that operates seasonally at the site. The repairs are acceptable to ADEC standard and the zip line managers have made protection of the upper and lower tailings caps a priority in the operations plan. |
Bruce Wanstall |
| 10/24/2011 |
Site Visit |
ADEC traveled to the site with Jason Ginter (Nortech) and the landowner to inspected both the upper and lower tailing site caps. The lower site appeared to be intact with intermittent vegetation growing over top of the one-foot cap. No odor was noticed and surface water draining off the southwest hillside was diverted into an open drainage channel flowing away from the tailing cap. The upper tailing cap appeared intact with intermittent vegetation. The main access road along side of the upper tailings area had a culvert installed to divert uphill surface water flow away from the tailing cap. In spring 2012 another inspection will be conducted by ADEC. |
Erik Norberg |
| 5/16/2013 |
Long Term Monitoring Complete |
Administrative action added during a quality control check. |
Kristin Thompson |
| 12/16/2013 |
Institutional Control Compliance Review |
IC review conducted. Set the reminder system to contact the RP in spring so that the gravel pads covering the tailings piles can be inspected. |
Evonne Reese |
| 5/15/2014 |
Site Visit |
DEC staff traveled to this site with a Nortech representative and the landowner to inspected both the upper and lower tailing site caps. The lower site cap was intact with intermittent vegetation growing over the top of the one-foot cap. No odor was present at either location. The upper tailings cap was also intact with intermittent vegetation. The abutments that prohibit vehicle traffic remain in place and seem to be effective. A culvert that diverts uphill surface water flow away from the tailings caps also seems to be effective since there was no sign of erosion on the cap’s surface. During the fall of 2014, after the tourist season, another inspection will be conducted by ADEC. A letter was issued to the landowner that includes the details of this inspection. |
Evonne Reese |
| 7/16/2014 |
Document, Report, or Work plan Review - other |
Reviewed the Sediment and Surface Water Sampling Report for Treadwell Tailings – Mexican Mine dated June 30, 2015 issued by NORTECH. This sampling event was voluntary and requested by AJT Mining Properties. Samples include sediment from the upper/lower tailings piles and surface water from the creek near the tailings piles. Samples were analyzed for metals (arsenic, barium, cadmium, total chromium, lead, mercury, selenium, and silver), cyanide, and pH. The water sample results indicated that surface water has not been impacted by contamination emanating from the tailings. The sediment sample results showed concentrations of arsenic, chromium, mercury, selenium, cyanide that exceeded cleanup levels and were consistent with historic mining and cyanide leach processing of heavy metal ore. The tailings piles will be inspected during the fall of 2014. |
Evonne Reese |
| 9/23/2014 |
Institutional Control Update |
A site inspection was performed on this date by by Evonne Reese and Sally Schlichting. A letter regarding the findings will follow in the near future. |
Evonne Reese |
| 11/12/2014 |
Institutional Control Update |
Fall site inspection letter issued and mailed to the responsible party. |
Evonne Reese |
| 5/11/2015 |
Institutional Control Update |
A spring 2015 site inspection has been planned for late May 2015. |
Evonne Reese |
| 5/20/2015 |
Update or Other Action |
Staff name changed from IC Unit to Danielle Duncan. |
Evonne Reese |
| 5/26/2015 |
Site Visit |
ADEC staff traveled to the site with J. Ginter (Nortech) and C. Johnson (AJT Properties) to inspect the caps on the upper and lower cyanide process tailings areas. The upper tailings cap is intact with thicker vegetation than observed during the fall 2014 inspection. The alders have grown nearly a foot tall and have no signs of stress (yellowed leaves, stunting etc.) at this time. There is a shot-rock utility road running through the upper tailings pile and it appears to be in good condition. The log abutment that prohibits vehicle traffic remains in place and effective. The lower tailings cap remains intact with little vegetation growing on the surface which may be a result of having used larger sized shot rock as armoring for the shot-rock utility road used occasionally by Alaska Canopy Adventures. The channel side of the tailings pile is contained with a sloped armor rock wall 4’ high and 225’ long and is in good condition. Overall, the cap appears to be providing a protective barrier between the tailings and the surface. Suggestions for maintenance of the institutional controls currently in place-
1. Please add copper to the list of potential COCs
2. The culvert input at the upper tailings cap is partially crushed at its opening. Please provide some protection for it so that is does not close and require replacement.
3. Please consider lining the bottom of the streambed at the lower tailings cap where water may travel at high velocity down slope carrying contaminated sediments. |
Danielle Duncan |
| 7/2/2015 |
Update or Other Action |
On June 23, 2015, NORTECH mobilized to the site to improve erosion and sediment control measures. Straw waddles were placed in areas to capture sediments and allow surface water drainage. A geotextile fabric was placed at the outfall of a drain pipe from further uphill. The fabric was weighted down with soils from nearby (crush and run used for the road/parking area). A section of straw wattle was placed in a U shape, surrounding the outflow. An additional two sections of straw wattles were placed further downstream of the drainage area as well. The wattles were secured in place with wooden stakes. |
Danielle Duncan |
| 9/29/2015 |
Exposure Tracking Model Ranking |
A new updated ranking with ETM has been completed for source area 71384 cyanide waste rock tailings pile. |
Danielle Duncan |
| 5/17/2016 |
Update or Other Action |
Sent a letter today requesting scheduling of the annual site inspection. |
Danielle Duncan |
| 7/5/2016 |
Site Visit |
Site visit with the RP and Nortech to inspect the tailings caps. The upper tailings cap is intact and was similar in appearance to previous site visits. The log abutment that prohibits vehicle traffic remains in place and effective. The culvert input at the upper tailings cap is in place. The lower tailings cap remains intact and as observed in the past site inspections, there is sparse vegetation growing on the surface. Suggestions for maintenance of the institutional controls currently in place-
1. The streambed at the lower tailings cap is receiving high amounts of runoff. ADEC requests that you install replacement straw wattle or another storm water protection best management practice (BMP) to reduce sedimentation into the stream.
2. According to ADEC records, the lower tailings cap covers 40,000 square feet and is 15 inches thick. The top 6 inches is crushed rock and the bottom 9 inches is larger shot rock. Please measure the depth of the current cap on the lower tailings pile and add material as necessary to ensure that a 15 inch cap covers the entire area. This will ensure that the institutional control of capping is preventing people and wildlife from contacting the tailings. Additionally, fortifying the cap should limit sediment migration to the intertidal area.
|
Danielle Duncan |
| 9/26/2016 |
Update or Other Action |
Rec'd a letter in response to my follow-up letter on the state of the tailings caps and erosion control measures. Drafted and sent a letter generally concurring with Nortech and look forward to reviewing information regarding additional erosion controls and determination of the current depth of the tailings cap. I instructed that no additional capping material be added prior to the ADEC's review of available information. |
Danielle Duncan |
| 6/4/2018 |
Update or Other Action |
Sent a request for an update letter. |
Danielle Duncan |
| 6/21/2018 |
Update or Other Action |
The responsible party is working with Nortech on a response to my request for update letter. |
Danielle Duncan |
| 7/23/2018 |
Meeting or Teleconference Held |
Met with J. Ginter of Nortech to discuss my request for update letter and upcoming site visit. There are currently 2 options due to the appearance of the cap as eroded: the options are add an additional 15 inches to re-cap it or sample the surface and analyze for metals to determine whether or not the cap remains effective. |
Danielle Duncan |
| 7/26/2018 |
Site Visit |
Site visit to inspect the tailings caps with Avista and Nortech. |
Danielle Duncan |
| 1/17/2019 |
Site Characterization Workplan Approved |
Approved the Tailings Cap Assessment plan this date. The plan outlines activities to investigate the thickness of the lower tailings cap, sample the fines on the surface of the cap, and install three concrete survey stands. |
Danielle Duncan |
| 5/16/2019 |
Site Visit |
Site visit with J. Barsis and Nortech to inspect the upper and lower tailings cap. Survey work has begun on the lower tailings cap and the cap (15 in) is uneven - some spots have 15 in. and others don't. Permanent survey monuments will be installed and additional cap material will be added and in the future, the depth of the cap will be evident from the monuments. there is no longer vehicular traffic on top of the lower cap. The upper cap area is still vegetated - run-off controls are still in place. The intertidal zone below the lower cap has abundant red staining and fine, yellow material exists underneath the surface sediment. This may require investigation in the future. |
Danielle Duncan |
| 8/14/2019 |
Update or Other Action |
Provided comments on the Tailings Cap Assessment report - expect to review a final version soon. |
Danielle Duncan |
| 9/6/2019 |
Institutional Control Update |
According to the Lower Tailings Cap Assessment Report Mexican Mine – Treadwell Mine Complex, the cap was evaluated for thickness and the thickness ranged from 7 to 14 inches thick. As a result, more material will be added to ensure that at least a 15-inch cap is present. |
Danielle Duncan |
| 1/17/2020 |
Update or Other Action |
The Alaska Department of Environmental Conservation (ADEC) Juneau Office has reviewed and approved the 2019 Mexican Mine Mill Tailings Cap Maintenance dated January 9, 2020 and prepared by NORTECH, Inc. on behalf of AJT Mining Properties Inc. (AJT). The report was received in our office on January 9, 2020 via electronic mail. All site activities conformed to the 2017 ADEC Field Sampling Guidance and the work plan approved by the ADEC, therefore, the report is approved in accordance with 18 AAC 75.335(d). The approved cleanup levels for this site remain as noted in the 2008 Conditional Closure letter. If more information becomes available in the future, and you would like to propose another cleanup level, ADEC will evaluate the request. |
Amy Rodman |
| 2/11/2020 |
Institutional Control Compliance Review |
I paid a personal visit to this property and took photos of the cap improvements with the addition of gravel to bring the overall cap thickness to 15 inches. Photos of this site visit are included in the Documents section of this database record. |
Evonne Reese |
| 8/12/2020 |
Institutional Control Update |
Review the need for the IC requirement site inspection frequency of twice yearly since the property is no longer being used for zipline operations. |
Evonne Reese |
| 5/3/2024 |
Institutional Control Update |
The inspection cycle for this property can be changed to less frequent since the property is no longer being used for a zipline business which means there currently is not as much foot and tourist transport vehicle traffic on the containment cap. I am proposing inspecting every two years. If this is approved I will update the IC details with this information. |
Evonne Reese |
| 5/23/2024 |
Document, Report, or Work plan Review - other |
In May 2024 a cap inspection and erosion and sediment controls maintenance of the upper and lower tailings caps were performed by Nortech staff. The inspections included walking the cap surface(s) and perimeter(s) and visually monitoring for indications of erosion and assessing the progress of re-vegetation. The upper cap surface is entirely covered with alder trees 20-30’ in height with exception of the utility road. No erosion or scouring was observed around the perimeter. The lower tailing cap was relatively unchanged since 2019 when the D1 gravel was placed to bring the cap up to 15 inches overlying the tailings. The lower tailings cap is effectively being revegetated from the perimeters inward. The desired 15” minimum cap depth is in place throughout the lower tailings cap area, with rock cap depths generally ranging from 15 to 19” thick. Additional cover fill is not necessary at this time.
|
Evonne Reese |
| 5/23/2024 |
Institutional Control Compliance Review |
IC compliance review conducted along with the review of the site inspection. Since this site is not being used by the tourist zipline company anymore, the foot traffic is limited and vehicle traffic is rare so the inspection frequency can be reduced to every other year. |
Evonne Reese |
