Final
Treatability Study Field Report
Treatability Study to Stabilize Intertidal
Tailings Deposits
Salt Chuck Mine Superfund Site
Remedial Investigation
Tongass National Forest, Alaska
Prepared for
U.S. Environmental Protection Agency
Region 10
^e0 sr-%
2 S \
January 8, 2014
Prepared by
CH2IVIHILLฎ
AES10
Architect and Engineering Services Contract
Contract No. 68-S7-04-01
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Contents
Section Page
Acronyms and Abbreviations vii
1. Introduction 1-1
2. Background 2-1
2.1 Purpose and Scope 2-1
2.2 Treatability Study Problem Definition, Goal, and Objectives 2-1
2.2.1 Problem Definition 2-1
2.2.2 Goal 2-1
2.2.3 Objectives 2-1
2.3 Treatability Study Area 2-2
2.3.1 Chemicals of Potential Concern 2-2
2.3.2 Project Area Overview 2-2
2.4 Erosion Processes Observed 2-4
2.5 Monitoring Streambank Migration using Aerial Photographs 2-7
2.6 Datum Used in the Treatability Study 2-7
2.6.1 Vertical Datum 2-7
2.6.2 Horizontal Datum 2-7
3. Implementation and Monitoring of Vegetation Plots for Tailings Deposit Stabilization 3-1
3.1 Vegetation Testing for Tailings Deposit Stabilization 3-1
3.1.1 Objectives and Performance Criteria for Potential Stabilization Measures at the West
Tailings Deposit 3-1
3.1.2 Vegetation Transplanting 3-1
3.1.3 Seeding 3-7
3.2 2013 Observations of Implementation and Initial Vegetation Monitoring 3-9
3.2.1 Deviations from Treatability Study Work Plan 3-14
3.2.2 Photograph Monitoring 3-15
3.2.3 Sampling and Analysis of Sediment/Tailings 3-15
3.2.4 Preliminary Vegetation Observations 3-18
4. Streambank Stabilization 4-1
4.1 Objectives for Streambank Stabilization Measures 4-1
4.2 Implementation of Streambank Stabilization Work 4-1
4.2.1 2013 Implementation Observations 4-2
4.2.2 Deviations from Treatability Study Work Plan 4-6
4.2.3 Photograph Points 4-6
4.2.4 Rock Quantities 4-6
4.2.5 Schedule/Tides 4-7
5. Erosion Monitoring 5-1
6. Objectives for Future Monitoring 6-1
6.1 Vegetation Monitoring 6-1
6.2 Streambank Stabilization and Erosion Monitoring 6-2
7. References 7-1
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CONTENTS, CONTINUED
Page
Appendices
A Photographs of Vegetation Plots - May 2013 and August 2013
B Vegetation Monitoring Data - May 2013 and August 2013
C Sediment Sample Data - May 2013
D Treatability Study Construction Drawings
E Photographs of Streambank Stabilization - August 2013
F Erosion Monitoring Baseline Information - May 2013
Tables
2-1 Summary of Observed Erosion Types, Locations, and Processes 2-4
3-1 Vegetation Transplanting Treatment Plots/Subplots and Species/Plant Material Types Established
in May 2013 3-7
3-2 Vegetation Transplanting Treatment Plots/Subplots and Species/Plant Material Types Established in
August 2013 3-7
3-3 Seed Treatment Plots and Seed Species Established in 2013 3-8
3-4 Summary Information for Vegetation Plots Established in 2013 3-10
3-5 Intertidal Plant Communities and Associated Approximate Elevations 3-11
3-6 Vegetation Coverage in Seed Plots 3-14
3-7 Summary of Results from Sediment Samples Collected from Vegetation Plots and Onsite Vegetation
Reference Area 3-15
3-8 Summary of Copper Concentration from Sediment Samples Collected from Vegetation Plots and
Onsite Vegetation Reference Area 3-16
3-9 Summary of Soil Texture from Sediment Samples Collected from Vegetation Plots and Onsite
Vegetation Reference Area 3-17
3-10 Copper and Total Organic Carbon Results for Tailings Samples Collected in the Study Area and the
Browns Bay Reference Area, 2011 and 2012 3-21
4-1 Estimated Rock Types, Quantities, and Sources 4-6
4-2 Gradation of Quarry Rock Used for Streambank Stabilization 4-7
IV
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CONTENTS, CONTINUED
Figures
1-1 Site Location Map 1-2
1-2 Vicinity Map 1-3
1-3 Overview of the Project Site and Intertidal Area 1-5
2-1 Comparison of Wetted Channel (Unnamed Stream A) in 1979 and 2006 Aerial Photographs 2-9
2-2 Comparison of 1979 and 2006 Wetted Channel (Unnamed Stream A) - Superimposed 2-11
3-1 2013 Treatability Study Area and Features As-Built 3-3
3-2 2013 Treatability Study Area and Features As-Built with Aerial Photography 3-5
3-3 Average Growth (square inches) of Sea Asparagus Plugs Transplanted in Vegetation Plot 4-SA on the
West Tailings Deposit in Late May 2013 and Measured in Late August 2013 3-13
3-4 2011 and 2012 Intertidal Sediment/Tailings Sample Locations at Salt Chuck 3-19
4-1 Construction Window during Neap Tide August 28 to September 1, 2013 4-7
5-1 Erosion Pin Monitoring Network 5-3
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V
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Acronyms and Abbreviations
EE/CA Engineering Evaluation/Cost Analysis
EPA U.S. Environmental Protection Agency
GPS global positioning system
mg/kg milligrams per kilogram
MLLW mean lower low water
NAD83 North American Datum 1983
NAVD88 North American Vertical Datum 1988
ppm parts per million
PVC polyvinyl chloride
R&M R&M Engineering-Ketchikan
Rl Remedial Investigation
TOC total organic carbon
TS Field Report Treatability Study Field Report
TS Work Plan Work Plan, Treatability Study to Stabilize Intertidal Tailings Deposits (CH2M HILL, 2013a)
USFS U.S. Forest Service
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VII
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1. Introduction
This Treatability Study Field Report (TS Field Report) documents the field activities and findings from the 2013
field effort to investigate approaches to stabilize intertidal tailings deposits at the Salt Chuck Mine Superfund Site,
Prince of Wales Island, Alaska (referred to in this report as the "Salt Chuck Mine Site" or the "Site"; see Figures 1-1
through 1-3). The activities performed were described in the Work Plan, Treatability Study to Stabilize Intertidal
Tailings Deposits (CH2M HILL, 2013a), hereinafter referred to as the "TS Work Plan." Subsequent efforts to
monitor and evaluate the performance of the stabilization measures that were implemented in 2013 (including
comparisons to earlier year's data) will be described in a first-year monitoring report.
The field effort outlined in the TS Work Plan was implemented in May and August 2013. The general approach to
the Treatability Study included activities to:
Test potential measures to stabilize eroding streambanks and tailings deposits in the intertidal area at the Salt
Chuck Mine Site.
Excavate tailings from the high flow path of Unnamed Stream A at two primary eroding locations.
Transplant and seed intertidal vegetation in test plots, with various treatment options, to evaluate whether
vegetation can establish and survive on areas of the broad exposed West Tailings Deposit.
Establish a simple erosion monitoring network to gain an understanding of the relative erosion at locations
onsite where different erosional processes were observed at streambanks and on the intertidal tailings
deposits.
Field work was implemented and/or monitored during the summer of 2013:
May 29 to 30, 2013 - Performed transplanting and seeding in the West Tailings Deposit in the intertidal area.
Collected sediment samples in the vegetation plots in the West Tailings Deposit and onsite vegetation
reference area southwest of the West Tailings Deposit as part of the remedial investigation. Established the
erosion monitoring networks in Unnamed Stream A and the West Tailings Deposit area, and collected baseline
erosion monitoring data.
August 26 to 30, 2013 - Implemented streambank stabilization of Unnamed Stream A, and monitored the first
few months of the growing season of the vegetation plots that were planted in the West Tailings Deposit that
occurred in late May 2013.
This TS Field Report includes the following sections:
Section 2, Background, summarizes the project purpose and scope, and describes the project area, goal and
objectives, and general approach of the Treatability Study.
Section 3, Implementation and Monitoring of Vegetation Plots for Tailings Deposit Stabilization, summarizes
implementation and monitoring of vegetation plots for the Treatability Study.
Section 4, Streambank Stabilization, summarizes the implementation and monitoring of the measures to
stabilize eroding streambank tailings along Unnamed Stream A for the Treatability Study.
Section 5, Erosion Monitoring, summarizes the activities to monitor erosion onsite at streambanks and on the
intertidal tailings deposits.
Section 6, Objectives for Future Monitoring, outlines the objectives for the future monitoring effort.
Section 7, References, provides the references cited in the TS Field Report.
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Figure 1-1
Site Location Map
Salt Chuck Mine Superfund Site, Alaska
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1 INTRODUCTION
Former
Salt Chuck
Unnamed Stream A
Mill Site
j"- Tailings Spit
West Tailings Deposit
Rock
Jetty
Piles with Whaling
On-site vegetation
reference area and
donor site for
transplanting
Unnamed Stream A
(with eroding
stream banks)
Figure 1-3, Overview of the Project Site and Intertidal Area
Note: Photograph courtesy of National Oceanic and Atmospheric Administration Fisheries, 2007.
The following appendices are also provided with this TS Field Report:
Appendix A includes photographs of vegetation plots taken in May 2013 and August 2013.
Appendix B includes vegetation monitoring data collected in May 2013 and August 2013.
Appendix C includes sediment sample data collected in May 2013 from the West Tailings Deposit and the
onsite vegetation reference area.
Appendix D includes Treatability Study construction drawings and as-built drawings.
Appendix E includes photographs of streambank stabilization of Unnamed Stream A taken in August 2013.
Appendix F includes erosion monitoring information for Unnamed Stream A and tailings deposits collected in
May 2013.
Work was conducted in accordance with the TS Work Plan and the Quality Assurance Project Plan (QAPP)
(CH2M HILL, 2013b), unless noted as a deviation in subsequent sections.
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1-5
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2. Background
This chapter summarizes the project purpose and scope, and describes the project definition, goal and objectives,
project area, and general approach of the Treatability Study.
2.1 Purpose and Scope
The purpose of this TS Field Report is to document the field activities that were implemented in 2013 and to
investigate approaches to stabilize intertidal tailings deposits at the Salt Chuck Mine Superfund Site, Prince of
Wales Island, Alaska (see Figure 1-1). The activities performed were described in the TS Work Plan. The
Treatability Study was based on Guidance for Conducting Treatability Studies under CERCLA (U.S. Environmental
Protection Agency [EPA], 1992). The Treatability Study was developed based on input from EPA, agency
stakeholders that attended project meetings in Anchorage on February 12 to 13, 2013, and a site meeting on
May 8, 2013, subject matter experts, and available site data.
The final remedy for the Salt Chuck Mine Site will be identified during the Feasibility Study phase; the findings
from the Treatability Study will aid in developing the Feasibility Study.
2.2 Treatability Study Problem Definition, Goal, and Objectives
2.2.1 Problem Definition
The problem definition that formed the basis of this Treatability Study was that persistent ongoing erosion and
transport of tailings deposits in the intertidal area at the Salt Chuck Mine Site have resulted in and are increasing
the potential for ecological exposure and risk in Salt Chuck.
The Salt Chuck Mine has been in existence for nearly 90 years. Due to environmental and other factors, the
containment and stability of the intertidal tailings have been eroded and transported over time, particularly as the
man-made piles with whaling and the rock jetty barriers have deteriorated. Aerial photographs over time
demonstrate the degradation of the piles/whaling and the rock jetty, and changes in the channel alignment and
morphology of Unnamed Stream A. This change in channel alignment/morphology and subsequent reduction in
stability of the piles with whaling and rock jetty, whether due to cyclical rainfall/tidal patterns or climatic changes,
have caused increased erosion, transport, and deposition of contaminated tailings into sediments adjacent to the
former Salt Chuck mill. Early analytical data indicate there is, at least, an increased ecological risk potential in
sediments in Salt Chuck caused by this recent increase in erosion and changes in channel alignment/morphology
(CH2M HILL, 2012 and 2013c).
2.2.2 Goal
The goal of the Treatability Study was to test, on a small scale, remedial alternatives that would be designed to
minimize or mitigate the potential to spread contamination offsite and to minimize or mitigate exposure on the
site itself.
2.2.3 Objectives
The specific objectives of the Treatability Study were:
1. Test erosion control measures using channel realignment of Unnamed Stream A.
2. Test the feasibility of excavating streambank tailings deposits in the intertidal area at specific locations
demonstrated by modeling to be the most unstable and erodible along Unnamed Stream A.
3. Test the ability to stabilize and potentially cover tailings to prevent/reduce exposure and to potentially
improve aesthetics by using revegetation techniques in the West Tailings Deposit area.
4. Identify key eroding locations along Unnamed Stream A and the intertidal tailings deposits, and understand
processes that can be addressed in the Feasibility Study.
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2-1
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2, BACKGROUND
5. Develop targeted stabilizing measures at key eroding locations for Unnamed Stream A that were
implemented in summer 2013 to reduce erosion and transport of tailings to sediments adjacent to the former
Salt Chuck mill.
6. Aid in developing the Feasibility Study.
7. Minimize disturbance of sediment during construction.
8. Monitor the performance of the stabilizing measures.
9. Make sure that the Treatability Study actions are not inconsistent with the final remedy.
2.3 Treatability Study Area
The Salt Chuck Mine Superfund Site includes the upland, intertidal, and subtidal areas near the former Salt Chuck
mine and mill. The Treatability Study focused on the intertidal area.
2.3.1 Chemicals of Potential Concern
Previous site investigations at the Salt Chuck Mine Site that document the release of contaminants to site media
are presented in the following documents:
Final Report, Removal Preliminary Assessment, Salt Chuck Mine, Ketchikan Ranger District, Tongass National
Forest, Region 10-Alaska (Bureau of Land Management, 1998)
Draft Report Engineering Evaluation/Cost Analysis (EE/CA), Salt Chuck Mine Tongass National Forest, Alaska
(URS, 2007)
Final Completion Report Non-Time Critical Removal Action Salt Chuck Mine Mill Prince of Wales Island, Alaska
(North Wind, 2012)
Preliminary Findings for Pre-Remedial Investigation, 2011 Field Sampling Activities Technical Memorandum
(CH2M HILL, 2012)
Salt Chuck Mine - Preliminary Findings for Remedial Investigation, 2012 Field Sampling Activities Technical
Memorandum (CH2M HILL, 2013c)
Based on these past site investigations, the general types of site-related contaminants identified include:
Metals at upland and intertidal, and subtidal areas
Polynuclear aromatic hydrocarbons at both upland and nearshore intertidal areas near the former mill site
Petroleum hydrocarbons at both upland and nearshore intertidal areas near the former mill site
2.3.2 Project Area Overview
Landmarks and features within the project area are shown on Figure 1-3 and include the following:
Unnamed Stream A is the primary stream that flows through the intertidal area. Mine tailings have been
historically placed in this stream and its floodplain. Over the years, the stream has formed a channel through
and around the tailings deposits, which form the streambank and continue to erode. This stream has been
referred to as Unnamed Stream or Unnamed Creek in previous project documents. In this TS Field Report, the
stream is referred to as Unnamed Stream A to distinguish it from a smaller stream on the eastern side of the
site.
The Tailings Spit is the highest point in the intertidal area near the former mill site and is formed by a mound
of tailings. The West Tailings Deposit is a large, gradually sloping area that extends southward from the
Tailings Spit and is composed of tailings.
The Piles with Whaling are piles with horizontal boards attached (called whaling). They are located along the
northern alignment of the West Tailings Deposit and Tailings Spit, and along the western side of the East
Tailing Deposit. The piles with whaling are presumed to have been constructed (at least initially) to prevent
the tailings from migrating into the deeper waters of Salt Chuck.
2-2
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2 BACKGROUND
The Rock Jetty was constructed in the early 1900s. This feature is approximately 230 feet long by 15 feet wide
and was constructed using uniform 4- to 8-inch quarry spalls. This feature is presumed to have been
constructed to prevent the tailings from migrating into the access channel that was used to barge materials to
and from the former mill site.
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2, BACKGROUND
2.4 Erosion Processes Observed
Erosion types arid processes that were observed in May 2013 to mobilize tailings onsite are summarized in Table 2-1. Each of these erosion processes may
involve different types of stabilizing measures.
TABLE 2-1
Summary of Observed Erosion Types, Locations, and Processes
Treatability Study - Salt Chuck Mine Superfund Site
Observed
Erosion Type
and Location
Interpreted Erosion Process
Photograph
1. Erosion of a. Slumping of approximately the
steep slopes lower one-third of steep banks
or banks caused by release of pore water
within tailings from saturated tailings while
pond surface water is below this point
(typically during lower tides).
b. Fluvial erosion of slumped
material at the toe of the bank
by Unnamed Stream A may be a
rate-limiting process for
slumping.
c. Rill and rainsplash erosion on
upper portion of steep banks,
above zone of slumping.
2-4
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2 BACKGROUND
TABLE 2-1
Summary of Observed Erosion Types, Locations, and Processes
Treatability Study - Salt Chuck Mine Superfund Site
Observed
Erosion Type
and Location
2. Fluvial erosion
of low vertical
strearnbariks
3. Erosion of
floodplain
surface within
former
tailings pond
(relatively low
flat surface on
inside bend of
large
meander
upstream of
tailings spit)
interpreted Erosion Process
Undercutting of vertical banks
along Unnamed Stream A
causing slumping in areas
distinct from the set of
processes listed under (1)
above.
Surface erosion by overbank
flow on portion of the floodplain
that is overtopped during high
tide and/or high flow events of
Unnamed Stream A.
Rill formation and channel
network development enhanced
by ebb tides and direct rainfall
on floodplain surface.
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2, BACKGROUND
TABLE 2-1
Summary of Observed Erosion Types, Locations, and Processes
Treatability Study - Salt Chuck Mine Superfund Site
Observed
Erosion Type
and Location
interpreted Erosion Process
Photograph
4. Surface
erosion of the
tailings
deposits
a. Rainsplash and sheet flow
caused by direct rainfall on
tailings surface during low tide.
Interaction of these two
processes enhances their
effectiveness at transporting
sediment, because particles
splashed into shallow sheet flow
are delivered more efficiently to
channel and bay.
b. Rill and gully erosion on the
tailings deposit surface. Ebb
tides and direct rainfall on
tailings deposits are creating rilll
networks that concentrate flow
and cause erosion. Gully
formation occurs where sloping
rills intersect a buried silt and/or
clay stratigraphic layer in the
tailings deposit. Gullies advance
headward and widen near the
channel of Unnamed Stream A.
c. Wave and tidal action on the
tailings deposit. Breaking waves
on the tailings deposit surface
may dislodge tailings/sediment
particles. Advancing and
retreating tides focused within
the rill network likely transport
dislodged particles.
d. Wind action during low-tide and
high-wind conditions transports
sand-sized tailings/sediment
over the tailings deposit surface
and exposed and unvegetated
portions of the tailings spit.
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2, BACKGROUND
2.5 Monitoring Streambank Migration using Aerial Photographs
Aerial photographs from 1979 and 2006 were used to digitize the channel of Unnamed Stream A to compare
alignments and channel migration over time (Figure 2-1). The 1979 aerial photograph was generously provided by
Michael Wilcox at the U.S. Forest Service (USFS), Tongass National Forest.
On Figure 2-2, the digitized channels of Unnamed Stream A are shown superimposed on each other. This shows
that within nearly 30 years, the channel has migrated by eroding into the banks of the tailings deposits
throughout the length of the channel.
Further comparison could be made with digital aerial photographs that become available to EPA in the future
following implementation of the Treatability Study.
2.6 Datum Used in the Treatability Study
2.6.1 Vertical Datum
The vertical datum for elevations presented in this TS Field Report is the North American Vertical Datum 1988
(NAVD88), unless otherwise noted. This vertical datum was used in the topographic survey that was originally
conducted in February 2013 by R&M Engineering-Ketchikan (R&M) and issued on July 1, 2013 (R&M, 2013a). R&M
updated the base map and topographic contour map in October 2013 following construction of the Treatability
Study (R&M, 2013b; see Appendix D2 and Appendix D3, respectively).
This vertical datum is different from what is used in tide tables published by the National Oceanic and
Atmospheric Administration, which is based on a vertical datum of mean lower low water (MLLW).
While surveying the topography on February 15, 2013, R&M surveyed the incoming tide elevations and noted the
time in order to correlate the surveyed elevations between NAVD88 and MLLW.
R&M established the following conversion between the vertical datums:
Converting from NAVD88 to MLLW is: MLLW = NAVD88 + 3.84 feet.
Converting from MLLW to NAVD88 is: NAVD88 = MLLW - 3.84 feet
2.6.2 Horizontal Datum
The horizontal datum of the topographic survey is Alaska State Plane, Zone 1 US Survey Feet, North American
Datum (NAD83) (2011), as was originally issued on July 1, 2013, by R&M and updated by R&M in October 2013
following construction of the Treatability Study (R&M, 2013a, 2013b; see Appendices D2 and D3).
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Wetted Channel
Digitized From 1979 Aerial Photography
Digitized From 2006 Aerial Photography
KHEIDEMAN 12/13/2013 11:17:36 AM
Notes:
(1) Aerial photography courtesy US Census
Bureau; approximate date 2006. NAD83,
UTM Zone 8N, Meters. Pixel size 1 meter.
^ (2) 1979 aerial photograph scanned from
original 9"x9" contact print provided by Figure 2-1
USPS, Tongass National Forest (Michael Wilcox) Comparjson of Wetted Channel
(Unnamed Stream A)
100 200 Feet in 1979 and 2006 Aerial Photographs
I ] Salt Chuck Mine Superfund Site, Alaska
&ER*
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Wetted Channel
Digitized From 1979 Aerial Photography
Digitized From 2006 Aerial Photography
Notes:
(1) Aerial photography courtesy US Census
Bureau; approximate date 2006. NAD83,
UTM Zone 8N, Meters. Pixel size 1 meter.
(2) 1979 aerial photograph scanned from
original 9"x9" contact print provided by
USFS, Tongass National Forest (Michael Wilcox)
o
L
100
1
200 Feet
Figure 2-2
Comparison of 1979 and 2006
Wetted Channel
(Unnamed Stream A)
- Superimposed
Salt Chuck Mine Superfund Site, Alaska
SER*
KHEIDEMAN 12/13/2013 11:'
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3. Implementation and Monitoring of Vegetation
Plots for Tailings Deposit Stabilization
This chapter summarizes implementation and monitoring of vegetation plots in the West Tailings Deposit area for
the Treatability Study.
3.1 Vegetation Testing for Tailings Deposit Stabilization
CH2M HILL staff conducted the vegetation transplanting and seeding on the West Tailings Deposit area as
described in the TS Work Plan (CH2M HILL, 2013a) on May 29 and 30, 2013. Vegetation plots are shown in
Figures 3-1 and 3-2.
Initial monitoring of the vegetation plots occurred from August 26 through 30, 2013; Appendix A contains
photographs of the vegetation plots. Limited additional vegetation transplanting also occurred during the week of
August 26, 2013.
3.1.1 Objectives and Performance Criteria for Potential Stabilization Measures at
the West Tailings Deposit
The objectives for potential stabilization measures at the West Tailings Deposit are as follows:
1. Identify key eroding along Unnamed Stream A and the intertidal tailings deposits, and understand processes
that can be addressed in the Treatability Study.
2. Develop targeted stabilizing measures at key eroding locations on the West Tailings Deposit.
3. Implement initial techniques to stabilize sediment on the West Tailings Deposit.
4. Develop and implement a strategy to monitor performance of stabilization measures on the West Tailings
Deposit.
5. Evaluate performance of stabilization techniques on the West Tailings Deposit.
6. Report results of techniques and recommendations for adaptive management on the West Tailings Deposit.
Initial performance criteria for the transplanted vegetation were hypothesized in the TS Work Plan as follows:
At least 25 percent of the transplanted plants will survive.
Percent areal cover of transplanted plants will increase at least 10 percent per year.
3.1.2 Vegetation Transplanting
Intertidal vegetation was transplanted using an experimental design to evaluate plant material types for each of
three main planting species. This design resulted in a total of 240 plants being transplanted, as shown in
Tables 3-1 and 3-2, and Figures 3-1 and 3-2. Vegetation was transplanted as plugs, sprigs, and live cuttings from
the onsite vegetation reference area, shown on Figures 1-3, 3-1, and 3-2.
3.1.2.1 Planting Species and Plant Material Types
Three main species and several plant material types were transplanted:
Beach wildrye (Leymus mollis)
Sprig (Plot number: 1-WR)
Plug (Plot number 2-WR)
Bering hairgrass (Deschampsia beringensis)
Plug (Plot number 3-BH)
Sea asparagus (Salicornia virginica)
Plug (Plot number: 4-SA)
Live cutting fragments (Plot numbers: 5-SA and 10-SA)
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3. IMPLEMENTATION AND MONITORING OF VEGETATION PLOTS FOR TAILINGS DEPOSIT STABILIZATION
3.1.2.2 Planting Season
Vegetation was primarily transplanted early in the growing season (May 29 and 30, 2013), when the plant
materials were vigorous and actively growing and could establish during the summer. Sea asparagus live cuttings
(Plot number 10-SA in Figure 3-1) were also planted on August 31, 2013. The reason for this was because during
transplanting in late May 2013, the sea asparagus sprouts were smaller (approximate 2 to 3 inches long) than
desired for transplanting live cutting fragments. Therefore, this additional sea asparagus live cutting plot was
planted in late August 2013 to evaluate the effect of transplanting longer (5- to 6-inch-long) sea asparagus cutting
fragments late in the growing season. Many of these cuttings exhibited fine root development as part of the late
summer growth pattern. For more details, see Section 3.1.5, Deviations in Treatability Study Work Plan.
3.1.2.3 Plot Size, Plant Spacing, and Density
Intertidal wetland transplants (plugs, sprigs, and live cutting fragments) were installed in six vegetation transplant
plots that are 25 feet wide by 10 feet long. The plots were divided into five subplots (one subplot for each
treatment) that are each 5 feet-wide by 10 feet-long to achieve a 2.5-foot plant spacing, with 8 plants per subplot
(2 plants x 4 plants). As a result, the 6 plots, with 5 subplots per plot, and 8 plants per subplot equals 240 total
transplants.
3.1.2.4 Vegetation Transplanting Treatments
Several experimental treatments were tested, which included combinations of rock, organic matter (various
seaweeds found onsite), and fertilizer packets.
In the TS Work Plan, it was hypothesized that rock could protect the transplanted plants and the sediment
substrate from erosion (as evidenced by the sea asparagus and alkaligrass [Puccinellia nutkaensis] that has
naturally colonized in association with rocks onsite, particularly near the rock jetty). It was predicted that the rock
would also provide structural diversity and roughness for catching organic matter (such as seaweed, leaf litter,
driftwood, seeds, and plant propagules) and sediment delivered during tidal action. The rock could also serve as a
substrate where marine organisms could attach (such as rock weed [Fucus species] and barnacles), particularly at
the lower tidal elevations onsite. The rock could also encourage future natural establishment of plants. Local
quarry rock was used that was approximately 3 to 6 inches in diameter.
A slow release fertilizer contained in individual packets (similar to a tea bag) was used. The coating on the
fertilizer is specially formulated for slow release over 1 to 2 years. The packets are manufactured by Reforestation
Technologies International, Salinas, California, and were supplied by Landscape Alaska in Juneau, Alaska. The
packets are formulated with nitrogen, phosphorus, and potassium at a percentage analysis rate of 22-10-7.
Four experimental treatments were applied to the transplanted vegetation and one treatment was used as a
control:
Control - No treatment was applied.
Rock - A single layer of quarry rock was loosely placed around the transplanted plants. This treatment was
used to test the benefits of rock.
Rock with Seaweed - A layer of native local seaweed was collected and placed on the ground surface and
pinned down with rock. This was hypothesized to serve as a natural mulch and erosion control blanket that
would decompose. This treatment was used to test the combined benefits of organic matter and rock.
Fertilizer - One packet of slow release fertilizer was installed several inches below the soil surface at the side
of the planting hole in contact with the plant roots. This treatment will be used to test the benefit of improved
sediment fertility.
Rock with Fertilizer - One packet of slow release fertilizer and a single layer of quarry rock was installed as
describe above. This treatment will be used to test the combined benefits of improved sediment fertility and
rock.
3-2
ES102513044044SEA
-------
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NOTES:
1. SURVEY OF AS-BUILT TOPOGRAPHY, PLANIMETRICS AND CONTROL POINTS WAS UPDATED BY RAM
ENGINEERING IN OCTOBER 2013.
2. HORIZONTAL DATUM IS ALASKA STATE PLANE, ZOfE 1 US SURVEY FEET, NAD 83 (2011). THIS WAS
DERIVED FROM MULTIPLE GPS OBSERVATION SOLUTIONS OBTAINED FROM THE NGS "OPUS" UTILITY.
SC 1" A 3 1/2" ALUMINUM TABLET SET IN AN EXISTING CONCRETE FOOTER AS SHOWN.
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-------
-------
3 IMPLEMENTATION AND MONITORING OF VEGETATION PLOTS FOR TAILINGS DEPOSIT STABILIZATION
TABLE 3-1
Vegetation Transplanting Treatment Plots/Subplots and Species/Plant Material Types Established in May 2013
Treatability Study - Salt Chuck Mine Superfund Site
Vegetation Transplanting Treatment Subplots3
Subplot 1 Subplot 3 Subplot 5
Species/Plant Control (X) Subplot 2 Rock with Subplot 4 Rock with Total Number of
Material Type (No Treatment) Rock (R) Seaweed (RS) Fertilizer (F) Fertilizer (RF) Transplants
Beach Wildrye (WR)
Sprig (1-WR) 8
Plug (2-WR) 8
Bering Hairgrass (BH)
Plug (3-BH) 8 8 8 8 8 40
Sea Asparagus (SA)
Plug (4-SA) 8 8 8 8 8 40
Cutting (5-SA) 8 8 8 8 8 40
Total Number of 40 40 40 40 40 200
Transplants
a Plot size is 25 feet by 10 feet. Subplot size is 5 feet by 10 feet, with plants spaced approximately 2.5 feet on center.
X=Control, R=Rock, RS=Rockwith Seaweed, F=Fertilizer, RF=Rockwith Fertilizer.
TABLE 3-2
Vegetation Transplanting Treatment Plots/Subplots and Species/Plant Material Types Established in August 2013
Treatability Study - Salt Chuck Mine Superfund Site
Vegetation Transplanting Treatment Plots3
Plot
Species/Plant
Material Type
Subplot 1
Control (X)
(No Treatment)
Subplot 2
Rock (R)
Subplot 3
Rock with
Seaweed (RS)
Subplot 4
Fertilizer (F)
Subplot 5
Rock with
Fertilizer (RF)
Total Number of
Transplants
Sea Asparagus (SA)
Cutting (10-SA)
8
8
8
8
8
40
Total Number of
Transplants
8
8
8
8
8
40
a Plot size is 25 feet by 10 feet. Subplot size 5 feet by 10 feet, with plants spaced approximately 2.5 feet on center.
X=Control, R=Rock, RS=Rockwith Seaweed, F=Fertilizer, RF=Rockwith Fertilizer.
3.1.3 Seeding
Seeding on the West Tailings Deposit was also tested using an experimental design to evaluate three main native
species (alkaligrass, Bering hairgrass, and tufted hairgrass) that are available as commercial seed. This design
included a total of nine seed treatment subplots, as shown in Table 3-3 and Figures 3-1 and 3-2.
ES102513044044SEA
3-7
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3. IMPLEMENTATION AND MONITORING OF VEGETATION PLOTS FOR TAILINGS DEPOSIT STABILIZATION
TABLE 3-3
Seed Treatment Plots and Seed Species Established in 2013
Treatability Study - Salt Chuck Mine Superfund Site
Seed Treatment Subplots3
Seed Species
Plot ID
Subplot 1
Control (X)
(No Treatment)
(pounds of seed)
Subplot 2
Rock(R)
(pounds of seed)
Subplot 3
Rock with
Seaweed (RS)
(pounds of seed)
Total Pounds of
Seed Applied
(rounded)
Date of Seed
Sowing
Tufted Hairgrass
6-TH
0.33
0.33
0.33
1.0
May 30, 2013
Bering Hairgrass
7-BH
0.33
0.33
0.33
1.0
May 30, 2013
Alkaligrass
8-AG
0.50
0.50
0.50
1.5
May 30, 2013
Alkaligrass
9-AG
0.5b
-
-
0.5
May 30, 2013
Lyngbye's Sedge
11-LS
0.3b
-
-
0.3
August 31, 2013
Total Pounds of
Seed Applied
(rounded)
2.0
1.2
1.2
4.3
a Plot size is 30 feet by 10 feet. Subplot size is 10 feet by 10 feet.
b Plot and subplot size is 5 feet by 5 feet (the plot consists of only one subplot).
X=Control, R=Rock, RS=Rock with Seaweed.
Availability of alkaligrass seed made it possible to add one additional subplot to test alkaligrass at a lower
elevation within its range of occurrence onsite. One hypothesis for future management was whether alkaligrass
seed could be used in combination with vegetation transplants and/or rock to increase roughness and the extent
of revegetation onsite.
Availability of natural seed production from the onsite vegetation reference area in August 2013 also made it
possible to add an additional subplot to test seeding with Lyngbye's sedge (Carex lyngbyei).
3.1.3.1 Species for Seeding
Two hairgrass species were tested (Bering hairgrass and tufted hairgrass), because both have potential for
establishment and occur onsite. Bering hairgrass is more tolerant of moist and salty conditions than tufted
hairgrass.
Alkaligrass is a sod-forming grass that is currently somewhat widespread onsite but is fairly sparse. It shows
decent natural colonization in the spaces between rocks in the rock jetty. According to Wright (2011), alkaligrass is
used on revegetation projects where the site is sometimes flooded by extremely high tides or storm surges. This
species does best on silty or gravelly coastal soils and is most often found in southcentral and southeast Alaska.
Alkaligrass is a common grass found in the nooks and crannies of rocks and boulders in the tidal zone.
Seed was obtained from Alaska Mill and Feed (Anchorage) in the following quantities:
Alkaligrass: 2 pounds, $4.49 per pound
Bering hairgrass (var. Norcoast): 1 pound, $14.25 per pound
Tufted hairgrass (var. Nortran): 1 pound, $13.41 per pound
Steve Rook at Alaska Mill and Feed (telephone number 907-222-2047) recommended a seeding rate of
approximately 1 pound per 1,000 square feet. However, a heavier rate was applied in the test plot of
approximately 1 pound per 300 square feet. Preparation of the seedbed involved raking with a stiff wire rake,
sowing the seed by hand, and rolling the soil with a 5-gallon bucket and tamping by foot.
In late August 2013, a small plot of Lyngbye's sedge was also planted to test the potential for it to establish in the
tailings; seeds were collected at that time from onsite plants.
3-8
ES102513044044SEA
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3 IMPLEMENTATION AND MONITORING OF VEGETATION PLOTS FOR TAILINGS DEPOSIT STABILIZATION
3.1.3.2 Seeding Season
Seeding occurred on May 30, 2013, to allow establishment during the summer growing season. Seeding of
Lyngbye's sedge occurred on August 31, 2013.
3.1.3.3 Plot Size
Seed was sowed in 10-foot by 10-foot square plots.
Seeding was tested in plots that are 30 feet wide by 10 feet long (excluding the additional subplots that were
added in the field for alkaligrass and Lyngbye's sedge). The plots were divided into three subplots (one subplot for
each treatment), each 10 feet wide by 10 feet long.
The seed plots were placed to avoid conflict with temporary access needed by construction equipment for
excavation on the tip of the tailings spit in late August. Optimal placement of the plots would have been directly
within the access route due to the desirable elevation for hairgrass. Therefore, the plots were shifted directly
downslope from the access route.
Because of the small additional amount of alkaligrass seed available when seeding was conducted in late May
2013, it was determined in the field to establish another smaller (approximately 5 foot by 5 foot) subplot to test
seeding of alkaligrass at a slightly lower elevation than Plot 7-BH, but within the observed range of alkaligrass
occurrence onsite. Seed only was tested without treatments.
Because Lyngbye's sedge seed was available from the onsite vegetation reference area in late August 2013, it was
determined in the field to establish one additional smaller (approximately 5 foot by 5 foot) subplot to test seeding
of Lyngbye's sedge on the West Tailings Deposit due to its prevalence in other intertidal areas of the Site. Seed
only was tested without treatments.
3.1.3.4 Vegetation Seeding Treatments
Several experimental treatments were tested, which included combinations of rock and organic matter
(seaweed). Two experimental treatments were applied to the seed plots and one treatment was used as a control
in the following subplots (excluding the additional subplots that were added in the field for alkaligrass and
Lyngbye's sedge):
Control - No treatment will be applied.
Rock - Due to the effort in transporting rock, rock placement was limited to placing two rows of quarry rock in
each subplot. Some additional rocks were scattered in each rock subplot. This treatment was used to test the
benefits of rock in providing protection to possibly improve seed establishment.
Rock with Seaweed - A layer of native local seaweed was collected onsite and placed on the seeded ground
surface and pinned down with rock (also in two rows). This was hypothesized to serve as a natural mulch and
erosion control that would eventually decompose. This treatment was used to test the combined benefits of
organic matter and rock.
Information about all the vegetation plots established during the 2013 Treatability Study is summarized in
Table 3-4.
Appendix B4 includes a table of coordinates (latitude/longitude) for each of the vegetation plots shown on
Figure 3-1 on the intertidal tailings area, as well as for the general location of the onsite vegetation reference
area.
3.2 2013 Observations of Implementation and Initial
Vegetation Monitoring
During planting, it was observed that the vegetation zones deviated slightly from those presented in Table 3-6 of
the TS Work Plan (CH2M HILL, 2013a). The dominant intertidal plant communities with refined elevation ranges
are summarized in Table 3-5.
ES102513044044SEA
3-9
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3. IMPLEMENTATION AND MONITORING OF VEGETATION PLOTS FOR TAILINGS DEPOSIT STABILIZATION
TABLE 3-4
Summary Information for Vegetation Plots Established in 2013
Treatability Study - Salt Chuck Mine Superfund Site
Plot ID
Dominant
Species
Plant
Material
Type
Planting
Date
Approximate
Elevation
(feet NAVD88)
Approximate
Elevation
(feet MLLW)
Sediment Sample
ID
1-WR
Beach Wildrye
Sprig
May 2013
13
17
SCSS-184
2-WR
Beach Wildrye
Plug
May 2013
12.5-13
16.5-17
SCSS-183
SCSS-9183
(Duplicate)
3-BH
Bering Hairgrass
Plug
May 2013
11.5
15.5
SCSS-181
4-SA
Sea Asparagus
Plug
May 2013
10.5-11
14.5-15
SCSS-185
5-SA
Sea Asparagus
Cutting
May 2013
10-10.5
14-14.5
SCSS-186
6-TH
Tufted Hairgrass
Seed
May 2013
11.5
15.5
SCSS-182
7-BH
Bering Hairgrass
Seed
May 2013
11-11.5
15-15.5
-
8-AG
Alkaligrass
Seed
May 2013
11
15
-
9-AG
Alkaligrass
Seed
May 2013
10.5
14.5
-
10-SA
Sea Asparagus
Cutting
August 2013
10
14
-
11-LS
Lyngbye's Sedge
Seed
August 2013
11.5
15.5
-
Onsite Vegetation
Reference Area
Beach Wildrye
-
-
>12
>16
SCSS-187
Onsite Vegetation
Reference Area
Bering Hairgrass
-
-
11-12
15-16
SCSS-188
Onsite Vegetation
Reference Area
Sea Asparagus
-
-
7.5-12
11.5-16
SCSS-189
Note: Onsite Vegetation Reference Area = Southwestern portion of site (see Figures 1-3, 3-1, and 3-2).
NAVD88 = North American Vertical Datum 1988
MLLW = mean lower low water
3-10
ES102513044044SEA
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3 IMPLEMENTATION AND MONITORING OF VEGETATION PLOTS FOR TAILINGS DEPOSIT STABILIZATION
TABLE 3-5
Intertidal Plant Communities and Associated Approximate Elevations
Treatability Study - Salt Chuck Mine Superfund Site
Vegetation Type
Species
Approximate Elevation
Range
(feet NAVD88)
Approximate Elevation
Range
(feet MLLW)
Upland alder and conifer forest
Alnus rubra, Tsuga
heterophylla
>14
>18
Beach wildrye
Leymus mollis
>12
>16
Bering hairgrass
Deschampsia beringensis
11-12
15-16
Sea asparagus Salicornia virginica
Alkaligrass Puccinellia nutkaensis
7.5-12 11.5-16
Lyngbye's sedge Carex lyngbyei
Seaside arrowgrass Triglochin maritime
Mud flat Fucus sp <8 <12
NAVD88 = North American Vertical Datum 1988
MLLW = mean lower low water
Photographs 3-1 through 3-5 discuss the observations made in late August 2013 after the first growing season
(2013) for the transplanted vegetation.
The beach wildrye plugs arid sprigs (in plots 1-WR and 2-
WR) did not appear healthy when observed in late
August 2013 after the first growing season. Few of the
sprigs had green leaves. Approximately half of the plugs
still exhibited some green leaves, but vigor was low.
Despite being watered during planting in late May 2013,
these plants were planted into dry tailings.
Uncharacteristically dry hot weather conditions in
summer 2013 continued and were challenging for plants
that did not receive regular precipitation during a
normal summer in Southeast Alaska.
Photograph 3-1A. Beach wildrye plugs in late August
2013 after the first growing season.
Photograph 3-1B. Beach wildrye sprigs in late August
2013 after the first growing season.
ES102513044044SEA
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3. IMPLEMENTATION AND MONITORING OF VEGETATION PLOTS FOR TAILINGS DEPOSIT STABILIZATION
Photograph 3-2. When observed in late August 2013,
the Bering hairgrass plugs were alive and thriving.
However, the plants did not appear to be as robust as
when they were originally planted. It is possible that
these plants may be showing some signs of salt toxicity
due to being placed at a slightly lower than optimal
elevation relative to the site. Bering hairgrass occurs
onsite in a narrow elevation band located typically
within less than 1 vertical foot downslope from beach
wildrye.
A positive feature is that multiple other plants are
included with the Bering hairgrass plugs that may
survive better at this location, such as sea asparagus,
goose tongue, arrowgrass (Triglochin maritima), and
alkaligrass.
The Bering hairgrass also showed signs of strong wave
action, as also exhibited by the sediment ripples visible
in the photo.
Photograph 3-3. The sea asparagus cuttings planted in
May 2013 all died. Cuttings in late May were too short
and not sufficiently developed for successful
transplanting. However, the May 2013 transplanted
plugs looked healthy and vigorous (shown in
photograph). Plugs in the control subplot showed
evidence of scour from wave action (bottom two rows in
photograph). Plugs in the other subplots did not show as
much scour except for the ones most exposed to the
waves (far right side of the photograph). Plugs that
received fertilizer appeared green and healthy. Rocks
that were placed around the plugs appeared to constrict
the spread of the elongating shoots.
Sea asparagus propagates vigorously from vegetative
shoots that are in contact with the soil/sediment. The
rocks may reduce contact of the shoots with the
soil/sediment, despite the protection that the rocks
provide.
Photograph 3-4. Alkaligrass seed showed germination
and growth. Results were better in the two subplots that
included rock, as compared to the control. No
germination of either hairgrass species was observed in
the seed subplots. Total failure of the hairgrass to
germinate may likely be the result of a chemical
intolerance (salt or metals). However, other variables
include the hot and dry summer, poor soil fertility, low
organic matter, and/or wave erosion.
3-12
ES102513044044SEA
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3 IMPLEMENTATION AND MONITORING OF VEGETATION PLOTS FOR TAILINGS DEPOSIT STABILIZATION
Photograph 3-5. Vegetation in the reference area onsite
was generally healthy and robust (beach wildrye in the
upper left, Bering hairgrass in the middle, and sea
asparagus on the right and between the hairgrass
bunches).
Growth data (measured by length and width of shoot spread) were collected for the sea asparagus plugs because
this species showed the most visible development. Figure 3-3 shows the increase in average growth (square
inches) per treatment (sample size=8 per each treatment) after 3 months of growth following transplanting (late
May 2013 to late August 2013).
May 2013
Aug 2013
0.0
IX 2R 3RS 4F
Vegetation Treatment
5RF
Figure 3-3, Average Growth (square inches) of Sea Asparagus Plugs Transplanted in Vegetation Plot 4-SA
on the West Tailings Deposit in Late May 2013 and Measured in Late August 2013
Note: lX=Coritrol, 2R=Rock, 3RS=Rock with Seaweed, 4F=Fertiiizer, 5RF=Rock with Fertilizer.
Vegetation coverage data from seed subplots were collected in August 2013 (measured by length and width of
germinated seed patches), as summarized in Table 3-6. No germinated seedlings from either the Bering hairgrass
or the tufted hairgrass were observed. Live germinated seedlings from alkaligrass in plot 8-AG were observed, and
coverage was greater in the rock and rock-seaweed plots than in the control (Table 3-6). Live germinated
seedlings from alkaligrass were also observed in plot 9-AG, which visually resembled those in plot 8-AG, but
coverage was not measured because it was a deviation from the TS Work Plan and did not have the subplot
replication of the other seed plots.
ES102513044044SEA
3-13
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3. IMPLEMENTATION AND MONITORING OF VEGETATION PLOTS FOR TAILINGS DEPOSIT STABILIZATION
TABLE 3-6
Vegetation Coverage in Seed Plots
Treatability Study - Salt Chuck Mine Superfund Site
Average Percent Vegetation Coverage3
Seed Species
Plot ID
Subplot 1
Control (X)
(No Treatment)
Subplot 2
Rock(R)
Subplot 3
Rock with Seaweed
(RS)
Tufted Hairgrass
6-TH-Seed
0
0
0
Bering Hairgrass
7-BH-Seed
0
0
0
Alkaligrass
8-AG-Seed
24.8
27.1
56.4
a Percent vegetation coverage is based on the average of two samples taken in each subplot to estimate the vegetation coverage within a
one-half-square-meter sampling frame placed randomly twice in each subplot.
X=Control, R=Rock, RS=Rockwith Seaweed.
Raw data for vegetation monitoring are included in Appendix B.
The weather in summer 2013 was hotter and drier than is typical for Southeast Alaska. This may have affected the
transplants and seeds.
Transplanted plugs typically included multiple species that were rooted in the soil/sediment. This provided several
benefits:
1. Helped test suitability for transplanting species other than the target dominant species in a particular
elevation zone.
2. Increased diversity by "inoculating" the tailings deposits with a variety of transplanted species.
3.2.1 Deviations from Treatability Study Work Plan
To test several conditions that were observed during the planting in late May 2013, limited additional
transplanting was conducted on August 30, 2013 (in combination with the site visit to implement the streambank
stabilization work). In late May 2013, the sea asparagus sprouts were only 2 to 3 inches long, which was not as
long as was desired for transplanting live cutting fragments. Therefore, an additional test plot (Plot number 10-SA)
was planted in late August 2013 to evaluate the effect of transplanting 5- to 6-inch-long sea asparagus cutting
fragments late in the growing season, many of which exhibited fine root development as part of the late summer
growth pattern (see Photograph 3-6).
A small seed plot was also planted in late August 2013 to test the potential for Lyngbye's sedge to germinate and
establish in the tailings using seed that was collected from plants onsite immediately prior to planting on
August 31, 2013.
Also, as part of the streambank stabilization work in late August 2013, beach wildrye sprigs were transplanted on
the relocated tailings that were grubbed as part of the streambank stabilization work. The location of these
plantings is shown on Figure 3-1 as the hatched area on the tailings spit (the figure notes this area as the
"approximate limits of relocated tailings covered with jute matting and planted with beach wildrye"). Therefore,
transplanting beach wildrye sprigs on the relocated tailings in August 2013 also serves to evaluate the effect of
transplanting sprigs late in the growing season during wet and cool weather (after a hot dry summer had passed).
3-14
ES102513044044SEA
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3 IMPLEMENTATION AND MONITORING OF VEGETATION PLOTS FOR TAILINGS DEPOSIT STABILIZATION
Photograph 3-6. Sea asparagus live cuttings with fine
roots that were obtained in late August 2013 and tested in
an additional vegetation plot (Plot number 10-SA on
Figure 3-1).
3.2.2 Photograph Monitoring
During the implementation of the Treatability Study in summer 2013, photograph points were established to
document and monitor the establishment of the vegetation.
Appendix A includes photographs of each vegetation plot in May 2013 and August 2013
3.2.3 Sampling and Analysis of Sediment/Tailings
In late May 2013, ten grab samples were collected to characterize the sediments in the vegetation plots and in the
onsite vegetation reference area (see Figures 1-3, 3-1, and 3-2). Of these, seven samples (including one field
duplicate) were collected from vegetation plots on the intertidal tailings deposits, and three samples were
collected from the existing onsite vegetation reference area. Locations of the sediment samples are shown on
Figure 3-1. Samples were collected in accordance with the QAPP (CH2M HILL, 2013b).
The agronomic analyses summarized in Table 3-7 show that the sediment samples collected from vegetation plots
in the West Tailings Deposit area are particularly low in organic matter, nitrogen, phosphorus, potassium, calcium,
zinc, and manganese. Organic matter and nutrient levels were considerably higher for the sediment samples in
the vegetation reference area, where vegetation appears vigorous and healthy. It is interesting that relatively high
levels of magnesium, sodium, sulfur, iron, copper (albeit slightly lower in the reference area than on the intertidal
tailings deposits), and boron were reported across all samples, suggesting that these elements may not be
primary factors that limit plant growth on the intertidal tailings deposits.
TABLE 3-7
Summary of Results from Sediment Samples Collected from Vegetation Plots and Onsite Vegetation Reference Area
Treatability Study - Salt Chuck Mine Superfund Site
Sample
ID
Organic
Matter
(%)
Nitrogen
N03-N
(ppm)
Phos-
phorus
NaHC
03-P
(ppm)
Potas-
sium
K
(ppm)
Mag-
nesium
Mg
(ppm)
Cal-
cium
Ca
(ppm)
Sodium
Na
(ppm)
Sul-
phur
S04-S
(ppm)
Zinc
Zn
(ppm)
Man-
ganese
Mn
(ppm)
Iron
Fe
(ppm)
Copper
Cu
(ppm)
Boron
B
(ppm)
PH
Vegetation Plots
3-BH -
Bering
hairgrass
plug
SS181
0.4
VL
3
VL
8
L
81
L
279
M
633
VL
1313
VH
122
VH
0.5
VL
1
VL
13
M
216
VH
2.3
H
7.7
6-TH -
T ufted
hairgrass
SS182
0.3
VL
5
VL
9
M
69
L
268
M
1515
L
1191
VH
118
VH
0.3
VL
1
VL
13
M
283
VH
2.1
H
8.1
2-WR -
SS183
0.4
5
6
62
201
717
1016
85
0.3
1
25
293
1.9
8.1
Beach VL VL L L M VL VH VH VL VL H VH H
wildrye plug
ES102513044044SEA
3-15
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3. IMPLEMENTATION AND MONITORING OF VEGETATION PLOTS FOR TAILINGS DEPOSIT STABILIZATION
TABLE 3-7
Summary of Results from Sediment Samples Collected from Vegetation Plots and Onsite Vegetation Reference Area
Treatability Study - Salt Chuck Mine Superfund Site
Sample
ID
Organic
Matter
{%)
Nitrogen
N03-N
(PPm)
Phos-
phorus
NaHC
03-P
(PPm)
Potas-
sium
K
(PPm)
Mag-
nesium
Mg
(PPm)
Cal-
cium
Ca
(PPm)
Sodium
Na
(PPm)
Sul-
phur
S04-S
(PPm)
Zinc
Zn
(PPm)
Man-
ganese
Mn
(PPm)
Iron
Fe
(PPm)
Copper
Cu
(PPm)
Boron
B
(PPm)
PH
2-WR
Beach
wildrye plug
S9183
(dup)
0.4
VL
51
H
7
L
63
L
228
M
697
L
1151
VH
97
VH
0.4
VL
1
VL
22
M
277
VH
1.7
M
8.0
1-WR
Beach
wildrye sprig
SS184
0.3
VL
79
VH
4
VL
76
L
266
M
208
VL
1381
VH
119
VH
0.4
VL
1
VL
8
L
210
VH
1.3
M
7.5
4-SA-Sea
asparagus
plug
SS185
0.4
VL
8
VL
2
VL
94
VL
299
M
2054
L
1429VH
135
VH
0.5
1
VL
2
VL
244
VH
3.3
VH
8.1
5-SA-Sea
asparagus
cutting
SS186
0.3
VL
7
VL
3
VL
83
VL
278
M
2157
L
1310
H
125
VH
0.5
VL
1
VL
9
L
282
VH
3.5
VH
8.3
Onsite Vegetation
Reference Area
Beach
wildrye
SS187
14.8
H
22
M
22
H
410
L
1877
H
1362
VL
9614
VH
479
VH
2.8
M
5
M
60
VH
126
VH
20.3
VH
7.0
Bering
hairgrass
SS188
6.6
H
9
VL
19
M
294
VL
1223
M
848
VL
7632
VH
385
VH
1.1
L
15
M
99
VH
60.5
VH
10.6
VH
6.4
Sea
asparagus
SS189
3.0
M
12
L
13
M
260
M
905
H
690
VL
3092
VH
280
VH
0.7
VL
2
L
15
M
191
VH
9.5
VH
7.1
Note: The depth of sampling was 0 to 0.5 feet.
VH = very high, H = high, M = medium, L = low, VL = very low.
dup = duplicate
ppm = parts per million
The copper concentrations from samples on the West Tailings Deposit are approximately one order of magnitude
greater than concentrations from samples in the onsite vegetation reference area. Copper concentrations in
sediment samples collected from the vegetation plots and the vegetation reference area are summarized in
Table 3-8. Copper concentrations from samples in the vegetation plots on the West Tailings Deposit showed a
range from 1,230 to 4,260 milligrams per kilogram (mg/kg), and an average of 2,506 mg/kg. Copper
concentrations from samples in the vegetation reference area showed a range from 168 to 495 mg/kg, and an
average of 278 mg/kg.
TABLE 3-8
Summary of Copper Concentration from Sediment Samples Collected from Vegetation
Plots and Onsite Vegetation Reference Area
Treatability Study - Salt Chuck Mine Superfund Site
Sample
ID
Copper
Cu
(mg/kg)
Vegetation Plots
3-BH - Bering hairgrass plug
SS181
1230
6-THTufted hairgrass seed
SS182
3010
2-WR - Beach wildrye plug
SS183
3900
2-WR - Beach wildrye plug
S9183 (duplicate)
4260
3-16 ES102513044044SEA
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3 IMPLEMENTATION AND MONITORING OF VEGETATION PLOTS FOR TAILINGS DEPOSIT STABILIZATION
TABLE 3-8
Summary of Copper Concentration from Sediment Samples Collected from Vegetation
Plots and Onsite Vegetation Reference Area
Treatability Study - Salt Chuck Mine Superfund Site
Sample
ID
Copper
Cu
(mg/kg)
1-WR - Beach wildrye sprig
SSI 84
1570
4-SA - Sea asparagus plug
SS185
2000
5-SA - Sea asparagus cutting
SS186
1570
Onsite
Vegetation
Reference Area
Beach wildrye
SS187
172
Bering hairgrass
SS188
168
Sea asparagus
SS189
495
Note: The depth of sampling was 0 to 0.5 feet,
mg/kg = milligrams per kilogram
In addition, the texture analyses summarized in Table 3-9 show all the samples have high percentages of sand, but
many of the samples include silt and clay, which results in a loamy texture. The samples collected nearest the
upper elevations of the Tailings Spit have the highest percentage of sand; however, beach wildrye is able to
establish in those sandy sediments that are above regular tidal inundation.
See Appendix C for more detail on the agronomic sample results. Results of the chemical analyses from EPA's
analytical lab are also included in Appendix C.
Results from samples collected from the West Tailings Deposit in 2013 are similar to results from previous years.
In 2011, CH2M HILL conducted a pre-Remedial Investigation (Rl) onsite. In 2012, CH2M HILL conducted Phase 1
Rl field sampling activities onsite. Samples of the intertidal sediment/tailings were collected and analyzed
(CH2M HILL, 2012; 2013c).
TABLE 3-9
Summary of Soil Texture from Sediment Samples Collected from Vegetation Plots and Onsite
Vegetation Reference Area
Treatability Study - Salt Chuck Mine Superfund Site
Sample ID
% Sand
% Silt
% Clay
Soil Texture
Vegetation Plot
3-BH - Bering hairgrass plug
SS181
74
20
6
Loamy sand
Not in a veg plot
SS182
86
8
6
Sand
2-WR - Beach wildrye plug
SS183
86
6
8
Sand
2-WR - Beach wildrye plug
S9183
(duplicate)
90
4
6
Sand
1-WR - Beach wildrye sprig
SSI 84
92
2
6
Sand
4-SA - Sea asparagus plug
SS185
48
40
12
Loam
ES102513044044SEA 3-17
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3. IMPLEMENTATION AND MONITORING OF VEGETATION PLOTS FOR TAILINGS DEPOSIT STABILIZATION
TABLE 3-9
Summary of Soil Texture from Sediment Samples Collected from Vegetation Plots and Onsite
Vegetation Reference Area
Treatability Study - Salt Chuck Mine Superfund Site
Sample ID
% Sand
% Silt
% Clay
Soil Texture
5-SA - Sea asparagus cutting
SS186
52
38
10
Loam
Onsite Vegetation Reference
Area
Beach wildrye
SS187
78
14
8
Loamy sand
Bering hairgrass area
SS188
74
16
10
Loamy sand
Sea asparagus
SS189
48
40
12
Loam
Figure 3-4 shows the locations where intertidal sediment/tailings were previously sampled by CH2M HILL in
August 2011 and July 2012, respectively (CH2M HILL 2012; 2013c). The 2011 and 2012 analyses of sediment
samples for copper and total organic carbon (TOC) are particularly relevant to the Treatability Study. The results
from the sediment/tailings samples were generally high in copper and low in TOC. Table 3-10 summarizes these
results. Copper concentrations and TOC are generally inversely proportional for the sediment/tailings samples
collected from the study area. Copper from the samples collected from the study area in 2011 and 2012 showed a
range from 111 to 3,870 mg/kg. In addition, TOC in these samples ranged from 379 to 7,060 mg/kg.
Samples were also collected in 2012 by CH2M HILL in Browns Bay to represent background sediment conditions at
the reference area. Browns Bay is located approximately 2 miles from the former Salt Chuck mill site (see
Figure 1-2), and is considered an area unimpacted by mining activities. Table 3-10 also summarizes concentrations
of copper and TOC in sediment from the reference area at Browns Bay. Copper concentrations ranged from
12.2 to 20.7 mg/kg, and an average of 16.2 mg/kg. These copper concentrations are an order of magnitude lower
than copper concentrations from samples collected in 2013 in the vegetation reference area onsite, and two
orders of magnitude lower than the copper concentrations from sediment/tailings samples collected in 2013 on
the West Tailings Deposit. In addition, TOC results from samples collected in 2012 from Browns Bay showed a
range from 10,400 to 31,800 mg/kg.
3.2.4 Preliminary Vegetation Observations
Despite the passage of over 70 years since mill operations ceased in 1941, natural colonization of vegetation on
the tailings deposits has been limited. Colonization has been challenging due to the generally unfavorable
characteristics of the tailings deposits that are uncharacteristic of intertidal sediments:
Coarse mineral substrate
Low organic matter
Low fertility
Possible phytotoxic concentrations of copper and/or other metals
Uniform exposed surface lacking topographic variation, microsites, and roughness elements such as rock or
logs
Erodible sediments exposed to wind and waves.
As of result of the lack of established vegetation on the intertidal tailings deposits, gradual and episodic erosion
and transport of tailings has been observed. In addition, wave and wind energy further erodes tailings and
dislodge establishing seedlings.
3-18
ES102513044044SEA
-------
2011 Selected Intertidal Sediment/Tailings
Sample Locations
2012 Selected Intertidal Sediment/Tailings
Sample Locations
Notes:
(1) Aerial photography courtesy US Census
Bureau; approximate date 2006. NAD83,
UTM Zone 8N, Meters. Pixel size 1 meter.
(2) GPS coordinates adjusted based on best
available data for the site
o
L
50
100 Feet
_J
Figure 3-4
2011 and 2012 Selected
Intertidal Sediment/Tailings
Sample Locations at Salt Chuck
Salt Chuck Mine Superfund Site, Alaska
SER*
-------
-------
3 IMPLEMENTATION AND MONITORING OF VEGETATION PLOTS FOR TAILINGS DEPOSIT STABILIZATION
TABLE 3-10
Copper and Total Organic Carbon Results for Tailings Samples Collected in the Study Area and the Browns Bay Reference
Area, 2011 and 2012
Treatability Study - Salt Chuck Mine Superfund Site
Location ID
Sample
Type
Sample ID
Date
Top Depth
(feet)
Bottom Depth
(feet)
Copper
(mg/kg)
TOC
(mg/kg)
Salt Chuck Study Area
SCSD-101
N
SCSD-101-0-0.5-08282011
28-Aug-ll
0
0.5
641
7060
SCSD-102
N
SCSD-102-0-0.5-08282011
28-Aug-ll
0
0.5
895
2970
SCSD-104
N
SCSD-104-0-0.5-08282011
28-Aug-ll
0
0.5
882
825
SCSD-105
N
SCSD-105-0-0.5-08282011
28-Aug-ll
0
0.5
1910
534
SCSD-105
N
SCSD-105-2-3-08292011
29-Aug-ll
2
3
980
379
SCSD-301
N
SCSD-301-07292012
29-J u 1-12
0
0.5
2530
1130
SCSD-302
N
SCSD-302-07302012
30-Jul-12
0
0.5
2650 J
590
SCSD-303
N
SCSD-303-07302012
30-Jul-12
0
0.5
2550 J
280
SCSD-304
N
SCSD-304-07292012
29-J u 1-12
0
0.5
1100
720
SCSD-307
N
SCSD-307-07302012
30-Jul-12
0
0.5
1250
455
SCSD-401
N
SCSD-401-07302012
30-Jul-12
0
0.5
3110 J
630
SCSD-401
FD
SCSD-701-07302012FD
30-Jul-12
0
0.5
3870 J
551
SCSD-402
N
SCSD-402-07302012
30-Jul-12
0
0.5
1430 J
859
SCSD-901
N
SCSD-901-07292012
29-J u 1-12
0
0.5
3210 J
-
SCSD-901-1-1.5
N
SCSD-901-1-1.5-07292012
29-J u 1-12
1
1.5
111 J
-
SCSD-902
N
SCSD-902-08012012
01-Aug-12
0
0.5
1190
-
Browns Bay Reference Area
SCSD-333
N
SCSD-333-08022012
02-Aug-12
0
0.5
13.3
19000
SCSD-334
N
SCSD-334-08022012
02-Aug-12
0
0.5
20.7
31800
SCSD-335
N
SCSD-335-08022012
02-Aug-12
0
0.5
20.5
13000
SCSD-336
N
SCSD-336-08022012
02-Aug-12
0
0.5
12.2
10400
SCSD-337
N
SCSD-337-08022012
02-Aug-12
0
0.5
14.1
23300
J = The analyte was positively identified; the quantitation is an estimation.
FD = Field duplicate sample
N = Normal sample
TOC = total organic carbon
However, some individual plants have become established in areas of the tailings deposits. This has occurred in
locations that are generally protected from wind, waves, and scourplaces where organic matter, fine sediment,
and nutrients may accumulate.
When Salt Chuck mine was in operation, tailings were deposited in the intertidal area near the mill. After mill
operations ceased, the tailings were exposed to the natural forces (tides, waves, wind, and stream flow), which
reshaped the tailings into their current condition.
ES102513044044SEA
3-21
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3. IMPLEMENTATION AND MONITORING OF VEGETATION PLOTS FOR TAILINGS DEPOSIT STABILIZATION
Slow colonization by vegetation is characteristic of substantially disturbed sites that require the re-formation and
development of soil processes. Substrate conditions are critical to plant and animal colonization and growth
(Zedler, 2001).
3-22
ES102513044044SEA
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4. Streambank Stabilization
This chapter summarizes implementation and monitoring of the measures to stabilize eroding streambank tailings
along Unnamed Stream A for the Treatability Study.
4.1 Objectives for Streambank Stabilization Measures
The objectives for streambank stabilization measures are to:
1. Identify key eroding streambank locations for Unnamed Stream A and understand processes that can be
addressed in the Treatability Study.
2. Develop targeted stabilizing measures at key eroding streambank locations for Unnamed Stream A.
3. Implement initial measures to stabilize eroding streambanks for Unnamed Stream A.
4. Develop and implement a strategy to monitor performance of streambank stabilization measures.
5. Evaluate performance of streambank stabilization measures for Unnamed Stream A.
6. Report results of streambank stabilization measures and recommendations for adaptive management.
4.2 Implementation of Streambank Stabilization Work
The Treatability Study focused on excavation of the tailings at two primary streambank erosion points along
Unnamed Stream A. These two locations are shown in Figure 3-1 and in Photographs 4-1 and 4-2 below.
Work was conducted from August 26 to 30, 2013. Preparatory work included:
Loading 115 bulk bags with 0.75 to 1 cubic yard of rock each at the quarry and hauling the material to the site.
Placing several loads at each of two locations to create a temporary access ramp for construction equipment.
Equipment used included:
Two Excavators: John Deere 120 and 130. Most streambank excavation work was completed with the JD 130.
Off-road fork lift: Gehl RS 8-44.
Flatbed trailer to transport bulk bags.
During work at both locations, tailings were excavated from the path of the high-flow channel of Unnamed
Stream A, and moved and placed nearby at a higher elevation in the intertidal area (at approximately the 12-foot
elevation or higher).
Prior to excavation of tailings at the west excavation area (see Figures 3-1 and 3-2), existing vegetation within the
limits of work was stripped and stockpiled to the side, and was replaced on top of the tailings after work was
completed. The purpose was to use existing vegetation to recolonize the relocated tailings after excavation was
complete.
During work at both excavation areas, the contractor isolated the work area from flowing water through use of
sand bags and silt fencing to control erosion and sedimentation.
The channel straightening of Unnamed Stream A was limited to removing the western section of the tailings spit,
including five piles and horizontal whaling boards. The rest of the piles were avoided to preserve historical features.
Relocating the stream at this location shortened the channel length by approximately 50 feet.
Construction drawings issued to implement the streambank stabilization in August 2013 are included in
Appendix D. Following implementation of the streambank stabilization in August 2013, R&M prepared the As-Built
Drawings, which are included in Appendix D (Appendix D2 includes the basemap, and Appendix D3 includes the
contour map; R&M 2013a, 2013b). Post-construction Photographs 4-1 and 4-2 from August 2013 are shown
below.
ES102513044044SEA
4-1
-------
4, STREAMBANK STABILIZATION
Photograph 4-1. Completed excavation, rock armoring,
and relocated channel at Tailings Spit.
Photograph 4-2. Completed excavation and rock armoring
at the west excavation area (see Figures 3-1 and 3-2).
4.2.1 2013 Implementation Observations
Photographs 4-3 through 4-10 depict and discuss the observations made during the field effort (photographs have
been provided where available).
Photograph 4-3. A layer of fatty clay can be observed
under much of the tailings deposits. This clay was a
byproduct of the mill process. Digging and exposing this
clay tended to release fine sediment and cause
turbidity. Weight on the tailings by equipment and/or
weight during placement of rock caused pumping of
silts out of the tailings, which cleared within 15 to 30
minutes after cessation of work or new weight being
placed on the slope.
4-2
ES102513044044SEA
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4 STREAMBANK STABILIZATION
I --Jl
Photograph 4-4. Five pilings on the Tailings Spit were
relatively easy to remove using the excavator bucket
and thumb.
Photograph 4-5. The combination of bulk bags and mud
mats allowed for temporary access of construction
equipment without needing to construct an access road
out of rock. The mud mats provided a barrier between
the tailings and the forklift wheels to allow the forklift
to haul bulk bags onto the tailings without requiring
decontamination of tailings from the forklift. Care was
taken to prepare the soil for mud mats such that they
could be laid flat and in contact with the soil. The
bamboo sticks in the mud mats tended to break
wherever the mud mats were spanning rocks,
depressions, or soft soils.
Photograph 4-6. Use of bulk bags allowed for very
controlled placement of rock by the experienced
operator.
ES102513044044SEA
4-3
-------
4, STREAMBANK STABILIZATION
Photograph 4-7. Two temporary ramps were
constructed using quarry rock for access of construction
equipment down the otherwise steep embankment.
These ramps were removed upon completion of the
work.
Photograph 4-8. Placing the grubbed vegetation and
topsoil back on the excavated tailings deposits and
covering with jute matting and/or driftwood provided
seed and rooted plants that could colonize the
relocated tailings.
Photograph 4-9A. Planting beach wildrye sprigs on the
relocated tailings in August 2013.
Sprigs of beach wildrye were planted on the relocated
tailings on the tailings spit prior to being covered with
jute matting.
4-4
ES102513044044SEA
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4 STREAMBANK STABILIZATION
Photograph 4-9B. Placement of jute matting on the
relocated tailings, which was subsequently staked in
place in August 2013,
Photograph 4-10. In the west excavation area, the
grubbed plant parts (such as sedges) were distributed
over the graded area, followed by sprinkling several
cubic yards of rock to test the concept of increasing
roughness in combination with the vegetation.
No adult salmonids were observed in Unnamed Stream A during the weeklong construction period (August 26
to 31, 2013).
No cultural resources were encountered during the excavation work in August 2013. According to USFS (2013),
the Treatability Study work crew did the best they could and retained as many features as possible, as evidenced
by the retaining of more pilings that originally planned and the retention of the dredge buckets.
Work during the neap tide with midday low tides provided a good construction window and long work hours.
Equipment was safely stored onsite, sufficiently above high tides on the tailings deposit to avoid the need for
decontamination at the end of each day. Construction equipment was decontaminated upon completion of the
work onsite.
ES102513044044SEA
4-5
-------
4. STREAMBANK STABILIZATION
4.2.2 Deviations from Treatability Study Work Plan
Photographs 4-11 arid 4-12 depict and discuss where deviations from the TS Work Plan occurred.
Photograph 4-11. Upon removal of the piles, whaling
boards, and tailings behind the whaling boards on
the western tip of the tailings deposit, areas of fatty
clay were observed at the western tip of the tailings
spit. The fatty clay was covered with rock to reduce
erosion and transport of the clay.
Photograph 4-12. To reduce the potential for erosion
and sediment transport, crushed rock with a
gradation of approximately 3-inch minus was placed
in a head-cutting gully near erosion monitoring
points R6A through R6E (Figures 3-1 and 3-2).
4.2.3 Photograph Points
During the implementation of the Treatability Study in August 2013, photograph points were established to
document and monitor the performance of the streambank stabilization.
Appendix E includes photographs of the streambank stabilization in August 2013.
4.2.4 Rock Quantities
Approximate quantities and sources are summarized in Table 4-1. The gradation of the quarry rock used for
streambank stabilization is provided in Table 4-2.
TABLE 4-1
Estimated Rock Types, Quantities, and Sources
Treatability Study - Salt Chuck Mine Superfund Site
Location for Use
Rock Type
Quantity of Bulk Bags
(0.75 to 1 cubic yard each)
Rock Source
Place rock armoring in the Tailings Spit excavation area
3- to 6-inch quarry rock
81
USFS quarry 2
Place rock armoring in the west excavation area
3- to 6-inch quarry rock
33
USFS quarry 2
Total
114
USFS = U.S. Forest Service
4-6
ES102513044044SEA
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4 STREAMBANK STABILIZATION
TABLE 4-2
Gradation of Quarry Rock Used for Streambank Stabilization
Treatability Study - Salt Chuck Mine Superfund Site
Maximum Dimension
Percent Passing
(inches)
100
18
70-100
8
0-50
5
0-10
3
4.2.5 Schedule/Tides
Construction work occurred during the neap tide at the end of August 2013, during which the high tides did not
exceed 9 feet NAVD88, as shown in Figure 4-1. A neap tide occurs when the difference between high and low tide
is the least. Constructing during a neap tide period extended the work hours and allowed the contractor to leave
the equipment on higher ground onsite without having to remove equipment from the intertidal area.
20
15
m 10
D
>
Z
r 5
;
$ 0
-5
-10
8/24/13 8/26/13 8/28/13 8/30/13 9/1/13 9/3/13 9/5/13
Figure 4-1. Construction Window during Neap Tide August 28 to September 1, 2013
Note: Tides in feet NAVD88.
During this construction period, base flows in Unnamed Stream A were unaffected by high tides until roughly
2 hours before and 2 hours after the predicted high tides. During this period, in-channel could not occur
(approximate site elevations 6 feet NAVD88 or 10 feet MLLW).
Predicted Tides for Kasaan Bay, Surrogate for Project Site
A A a /\ ft
fl A A A
-Hill
All A / \
MjW
- - V
\l v VT
vV
Jx 11 y y
ES102513044044SEA
4-7
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5. Erosion Monitoring
This chapter summarizes the activities to monitor erosion of the tailings deposits.
During the reconnaissance site visit in early May 2013, a simple monitoring network was established to measure
baseline erosion as of May 2013. The basis of the monitoring network was the installation of vertical stakes, made
of polyvinyl chloride (PVC) or acrylic (as opposed to steel rebar, which contains metals and could affect samples
collected nearby and which would corrode in marine environment and present a potential public safety concern).
The vertical erosion stakes, or pins, are each about 1 meter long, and were pounded into the surface so that only
about 10 centimeters were exposed. The actual amount of exposed pin above the ground surface was measured
for each stake, to serve as a benchmark for the ground surface elevation at the time of installation. The heights of
the pins will be measured during a future site visit to monitor the amount of ground surface lowering at each of
the points.
Stakes were installed in a way meant to quantify the observed erosion processes (see Photograph 5-1 and
Figure 5-1). Erosion processes were previously described in Table 2-1. Thus, some stakes were installed on steep
slopes in the tailings pond (erosion category 1), others meant to monitor rill erosion in the rill network (erosion
category 4), and still others on the floodplain surface (erosion category 3). For measuring bank retreat (erosion
category 2), the distance between pins installed near eroding banks and the bank edge was measured.
Several of the monitoring pins were damaged during implementation of the streambank excavation and
placement of rock in late August 2013.
A discussion of the observed erosion processes, the erosion pin monitoring network, a list of the pins, their spatial
coordinates, and initial exposed pin heights are provided along with more details in Appendix F.
Photograph 5-1. Installation of an erosion
monitoring pin (white PVC) in a rill network on the
floodplain upstream of the Tailings Spit in early
May 2013.
'
?.KL
hBSsHB
ES102513044044SEA
5-1
-------
-------
Notes:
(1) Aerial photography courtesy US Census
Bureau; approximate date 2006. NAD83,
UTM Zone 8N, Meters. Pixel size 1 meter.
(2) GPS coordinates adjusted based on best
available data for the site
Erosion Point
Bank
ฎ Floodplain
Plain
Major Elevation Contour (feet NAVD88)
Minor Elevation Contour (feet NAVD88)
Approximate Shoreline(Mean High Tide)
Rock Jetty
Barge
Piling Structure
Lake
Ellen
Salt Chuck
Browns
Bay
Figure 5-1
Erosion Pin Monitoring Network
Salt Chuck Mine Superfund Site, Alaska
Gosti
Island
*>EPA
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6. Objectives for Future Monitoring
This chapter summarizes the objectives for future monitoring of the treatability study stabilization measures that
were implemented in 2013.
6.1 Vegetation Monitoring
Objectives for future vegetation monitoring related to the Treatability Study are listed below.
Assess the establishment and development of:
Vegetation plugs and sprigs that were transplanted in May 2013 (plot numbers 1-WR, 2-WR, 3-BH, and 4-SA).
Bering hairgrass seed that was planted in May 2013 and had subsequently germinated (plot numbers 8-AG
and 9-AG).
Sea asparagus live cuttings that were transplanted in August 2013 (plot number 10-SA).
Lyngbye's sedge seed that was planted in August 2013 and had subsequently germinated (plot number 11-LS).
Existing established vegetation in the onsite reference area.
Beach wildrye sprigs that were planted in August 2013 on the relocated tailings on the Tailings Spit. Also,
observe any other plant species that may have re-established on the relocated tailings as a result of the
construction method that involved segregation and replacement of topsoil, which included live plant
materials (such as, Bering hairgrass, and beach wildrye).
Plant species that may have re-established within the construction limits of the West Excavation Area as a
result of the construction method that involved segregation and replacement of topsoil, which included live
plant materials (such as Lyngbye's sedge, Bering hairgrass, and beach wildrye).
Vegetation within the route used for construction equipment to access the West Excavation Area. This route
was protected using mud mats to minimize disturbance to intertidal vegetation.
Other specific activities to be conducted during vegetative monitoring are to:
Take photographs from the same vantage points as were taken in May and August 2013, including the
established vegetation in the onsite reference area.
Carefully dig (to minimize disturbance) around roots of several transplanted plugs, sprigs, live cuttings, and
germinated seedlings to evaluate and photograph the elongation of roots into tailings beyond the
transplanted or germinated root mass (such as plot numbers 1-WR, 2-WR, 3-BH, 4-SA, 8-AG, 9-AG, 10-SA, and
11-LS). Note which plants specimens in each plot/subplot were disturbed. Carefully replant specimens and
minimize root damage/disturbance. Note several test transplants were made outside of the vegetation plots
to refine the initial planting methods; these could be used for destructive sampling without damaging the test
plots.
Identify whether any of the elongated aboveground shoots from sea asparagus plugs in plot number 4-SA
show evidence of vegetative attachment/rooting into the tailings.
Record observations of noticeable effects of wave, wind, and tidal erosion on the vegetation plots and subplot
treatments, as well as observed beneficial effects of treatments (such as rock, or rock and seaweed) in
mitigating these processes, especially in comparison to the initial placement and orientation of the vegetation
treatments.
Measure aboveground plant size (length and width of shoots) of sea asparagus plugs in plot number 4-SA as
was done in May and August 2013, and compare the growth results to the 2013 measurements.
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6 OBJECTIVES FOR FUTURE MONITORING
Measure aboveground plant size (length and width) of Bering hairgrass plugs in plot number 3-BH as was
done in May 2013, and compare the growth results to the 2013 measurements.
Measure baseline plant size (length and width of new shoots) for future monitoring if the transplanted live
cuttings of sea asparagus in plot number 10-SA have survived.
Quantify subplot coverage of germinated seed of alkaligrass in plot number 8-AG as was done in August 2013,
and compare results to the 2013 measurements.
Quantify plot coverage of germinated seed of alkaligrass in plot number 9-AG.
Quantify plot coverage of germinated seed of Lyngbye's sedge in plot number 11-LS.
Make recommendations and initial conclusions about the observed performance of using vegetation to aid in
stabilizing intertidal tailings.
6.2 Streambank Stabilization and Erosion Monitoring
Objectives for future streambank stabilization and erosion monitoring related to the Treatability Study are listed
below.
Assess the stability of:
The relocated section of stream, the rock-stabilized streambank, and the relocated and stabilized tailings at
the western tip of the Tailings Spit that were constructed in 2013.
The rock-stabilized streambank, scattered rock on the floodplain, and the relocated and stabilized tailings at
the West Excavation Area that were constructed in August 2013.
Crushed quarry rock that was placed in the one head-cutting gully in August 2013 (near erosion pins R6A
through R6D).
Other specific activities to be conducted during streambank stabilization and erosion monitoring are to:
Take photographs of each stabilization measure from the same vantage points as were taken in August 2013.
Record observations of noticeable effects of wave, wind, tidal, and fluvial erosion onsite in response to the
stabilization measures and/or as a result of another year of exposure to these processes.
Measure the height of each erosion monitoring pin above ground surface to estimate the relative amount of
ground surface lowering since 2013 due to erosion processes at each monitoring point.
Digitize and compare the alignment of Unnamed Stream A on digital aerial photographs that become available
to EPA in the future, following implementation of the Treatability Study (i.e., after August 2013).
Make recommendations and initial conclusions about the observed performance of using rock to aid in
stabilizing intertidal tailings onsite.
Comment on whether effects could be observed in the future after construction equipment was used in the
intertidal area to implement the Treatability Study.
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7. References
Bureau of Land Management. 1998. Final Report, Removal Preliminary Assessment, Salt Chuck Mine, Ketchikan
Ranger District, Tongass National Forest, Region 10 - Alaska. Prepared by U.S. Bureau of Land Management,
Juneau Field Office, Interagency Agreement No. 961A-10-012. April 1998.
CH2M HILL. 2012. Salt Chuck Mine - Preliminary Findings for Pre-Remedial Investigation, 2011 Field Sampling
Activities Technical Memorandum. Prepared for U.S. Environmental Protection Agency, Region 10. May 7,
2012.
CH2M HILL. 2013a. Work Plan, Treatability Study to Stabilize Intertidal Tailings Deposits, Salt Chuck Mine Remedial
Investigation, Tongass National Forest, Alaska. Prepared for U.S. Environmental Protection Agency, Region 10.
May 23, 2013.
CH2M HILL. 2013b. Quality Assurance Project Plan, Salt Chuck Mine Remedial Investigation, Tongass National
Forest. Prepared for U.S. Environmental Protection Agency, Region 10. May 14, 2013.
CH2M HILL. 2013c. Salt Chuck Mine - Preliminary Findings for Remedial Investigation, 2012 Field Sampling
Activities Technical Memorandum. Prepared for U.S. Environmental Protection Agency, Region 10. February
27, 2013.
National Oceanic and Atmospheric Administration. 2007. Alaska Shore Zone Coastal Mapping and Imagery.
Available at http://alaskafisheries.noaa.gov/shorezone/.
North Wind. 2012. Final Completion Report Non-Time Critical Removal Action Salt Chuck Mine Mill Prince of
Wales Island, Alaska. Prepared for U.S. Forest Service. April.
R&M Engineering-Ketchikan, Inc. (R&M). 2013a. Salt Chuck Intertidal Topographic Survey. Prepared for CH2M HILL
by R&M Engineering-Ketchikan, Inc., Ketchikan, AK. July 1, 2013.
R&M Engineering-Ketchikan, Inc. (R&M). 2013b. Salt Chuck Intertidal Tailings Topographic Survey, As-Built
Drawings. Prepared for CH2M HILL by R&M Engineering-Ketchikan, Inc., Ketchikan, AK. October 2013.
U.S. Environmental Protection Agency (EPA). 1992. Guidance for Conducting Treatability Studies under CERCLA.
EPA/540/R-92/071a.
URS. 2007. Draft Report Engineering Evaluation/Cost Analysis (EE/CA) Salt Chuck Mine, Tongass National Forest,
Alaska. Prepared by URS Group, Inc. Prepared for U.S. Department of Agriculture Forest Service, Alaska
Region. March.
U.S. Forest Service (USFS). 2013. R201310055415 Work Plan Treatability Study to Stabilize Intertidal Tailings
Deposits at the Salt Chuck Mine Site (CRG-00019) Draft Report. Prepared by Tim Marshall, U.S. Department of
Agriculture, Forest Service, Tongass National Forest. November 2013.
Wright, Stoney J., and Philip K. Czapla. 2011. Alaska Coastal Revegetation & Erosion Control Guide. State of Alaska
Plant Materials Center. August 2011. Available at http://plants.alaska.gov/reveg/.
Wright, Stoney J. 2011. "Beach wildrye planting guide for Alaska." Appendix A in Wright, Stoney J., and Philip K.
Czapla. 2011. Alaska Coastal Revegetation & Erosion Control Guide. State of Alaska Plant Materials Center.
August 2011. Available at http://plants.alaska.gov/reveg/.
Zedler, J.B. 2001. Handbook for Restoring Tidal Wetlands. CRC Press. 439p.
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