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Site Report: AK Juneau Rock Dump (a.k.a. Gastineau Mine)

Site Name: AK Juneau Rock Dump (a.k.a. Gastineau Mine)
Address: Head of Thane Road, Juneau, AK 99801
File Number: 1513.38.009
Hazard ID: 402
Status: Active
Staff: Danielle Duncan, 9074655207
Latitude: 58.287588
Longitude: -134.390259
Horizontal Datum:WGS84

We make every effort to ensure the data presented here is accurate based on the best available information currently on file with DEC. It is therefore subject to change as new information becomes available. We recommend contacting the assigned project staff prior to making decisions based on this information.


From 1901 to 1951 AK Juneau Gold Mining Company operated a gold mine at the site. During its operation, 55 million tons of ore were processed. Waste ore from the mill was transported to the shore of the Gastineau Channel and dumped on the intertidal mud flat, covering an area of 60 to 70 acres with a maximum depth of 30 feet below ground surface (bgs) (a.k.a rock dump). From historical documents, it appears as though no processing (cyanide or mercury) was done. The metals data reflects that. From 1959 to the early 1990s, the north portion of the site has been used for oil storage/transfer activities; the middle, and largest portion of the site, has been used for dumping trash/junk cars and off-road vehicle use; and the southern portion has been used as a sewage treatment plant by the City of Juneau. Sampling events in 1989 and 1990 indicate soil and groundwater contamination above ADEC cleanup levels. The site, now used as an industrial complex has been subdivided into multiple parcels with multiple owners and is mostly paved. Surface water, air transport, and leeching of sediments into the intertidal zone are all exposure risk pathways. January 1990 data documented the following metals in exceedance of ADEC cleanup levels (ranges given in mg/kg): As: 9.1-29 Cd: 3.8-16 Cr: 47-78 Pb, Se, and Hg were present at concentrations below ADEC cleanup levels.

Action Information

Action Date Action Description DEC Staff
6/15/1987 Report or Workplan Review - Other In 1987, Golder associates collected surface soil sample and groundwater samples. Five monitoring wells installed and sampled contained arsenic up to 0.017 mg/L, cadmium up to 0.0021 mg/L, and lead up to 0.20 mg/L. Ten Soil samples collected contained arsenic up to 26.9 mg/kg, chromium up to 51.2 mg/kg, and lead up to 158 mg/kg. This investigation suggests that there are localized "hot spots" of metals over ADEC cleanup levels, but there is not a significant amount of contamination throughout the entire Juneau Rock Dump area. Grant Lidren
6/1/1990 Site Characterization Report Approved ADEC received Site Inspection Report for Alaska Juneau Dump, dated June 1990, submitted by ecology and environment. Six surface composite soil samples collected from tailings in the inter-tidal zone and deposits near windblown samplers contained arsenic up to 28.8 mg/kg, cadmium up to 15.9 mg/kg, and chromium up to 78.4 mg/kg. The conclusions of this report state, “Results…indicate the tailings at the AJ Dump contain heavy metals that may be released to the surrounding environment through surface water or as airborne particulates. Although the concentrations of heavy metals detected in the tailings do not indicate the need for emergency actions, the tailings should be evaluated with regard to their potential effects on humans through ingestion and inhalation. It should be noted that particulate releases from the site during severe wind-storms may be in violation of ambient air standards specified in 18 AAC 50.20 and 50.110.” Grant Lidren
2/26/2008 Exposure Tracking Model Ranking Initial ranking with ETM completed. Bill Janes
1/27/2010 Update or Other Action Site transfered from Bill Janes to Grant Lidren Susan Carberry
3/12/2010 Exposure Tracking Model Ranking Initial ranking with ETM completed for source area id: 71381 name: Mine Tailings Grant Lidren
7/1/2010 Update or Other Action File transferred to Anchorage 1/27/2010 Susan Carberry
8/23/2010 Update or Other Action After file review on this date, further evaluation of exposure pathways appears warranted. Heavy metals could potentially be leeching into the Gastineau channel. Grant Lidren
11/9/2010 Update or Other Action File transferred back to Juneau. Linda Nuechterlein
9/11/2013 Update or Other Action Staff changed from Erik Norberg to Denise Elston. Kristin Thompson
10/11/2013 Site Visit DEC staffs, Bill Janes, Sally Schlichting, and Denise Elston inspected the site because a 1990 investigation found that tailing in the inter-tidal zone and deposits near windblown samplers contained arsenic up to 28.8 mg/kg, cadmium up to 15.9 mg/kg, and chromium up to 78.4 mg/kg. There are two distinct areas at this site currently. We are dealing with a more developed and commercialized parcel than it was in 1990 but also an inter-tidal mud flat that poses a ecological and human health exposure risk. DEC will engage with CBJ on possible site characterization efforts. Denise Elston
11/12/2014 Update or Other Action Rec'd letter from Region 10 EPA stating that the Thane Mine Dump EPA Site Identification # AKD981767320 previously considered the thane Mine Dump Site "excluded" as an eligible response site under CERCLA Section 101(41)(C)(i). However, EPA has determined that no further federal action will be taken and therefor considers this site an eligible response site under the statute. Signed by D. Zhen, acting manager of the Assessment and Brownfields Unit. Danielle Duncan
10/7/2015 Exposure Tracking Model Ranking A new updated ranking with ETM has been completed for source area 71381 Mine Tailings. Danielle Duncan
9/21/2016 Update or Other Action Recently received a call from a consultant who may be preparing to do some work on site to further development. I shared what information we have and reminded them that a work plan must be reviewed by ADEC if that work would be involving contaminated sediments. Danielle Duncan
12/15/2016 Update or Other Action Sent a letter today regarding the paving and/or asphalting and building construction on 2 lots on site. Danielle Duncan
1/23/2017 Update or Other Action According to the letter dated Dec. 15, 2016, the ADEC requires the analysis of RCRA-8 metals on any soil proposed to be moved off-site as part of the development project. This is in addition to a completed soil transport approval form. Danielle Duncan
6/1/2018 Exposure Tracking Model Ranking A new updated ranking with ETM has been completed for source area 71381 Mine Tailings. Danielle Duncan

Contaminant Information

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