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Coal Valley Resources Inc. – Obed Mountain Mine
2014 Sediment Trap Assessment
Environmental Protection Order No. EPO-2013/34-CR
Submitted to:
Alberta Energy Regulator
March 2015
CVRI – Obed Mountain Mine
2014 Sediment Trap Assessment
TABLE OF CONTENTS
Page
Table of Contents .................................................................................................................................................. i
List of Figures ....................................................................................................................................................... ii
List of Tables ......................................................................................................................................................... ii
List of Appendices ............................................................................................................................................... ii
1.0
INTRODUCTION...................................................................................................................................3
1.1
Background ..........................................................................................................................................3
1.2
Sediment Trap Decision Process .......................................................................................................3
2.0
SEDIMENT TRAP DESIGN AND CONSTRUCTION ...................................................................4
2.1
Sediment Trap Design.........................................................................................................................5
2.2
Site Preparation ....................................................................................................................................5
2.3
Construction .........................................................................................................................................6
2.4
Trap Tie-In ............................................................................................................................................7
3.0
OPERATIONS & MAINTENANCE....................................................................................................9
3.1
Vegetation .............................................................................................................................................9
3.2
Erosion Control ..................................................................................................................................10
3.3
Silt Curtains ........................................................................................................................................10
3.4
Sediment Removal.............................................................................................................................12
3.5
Fish Salvage ........................................................................................................................................12
4.0
MONITORING .....................................................................................................................................13
4.1
Water Quality .....................................................................................................................................13
4.2
Sediment Trap Inspections ...............................................................................................................14
4.3
Bathymetry Data ................................................................................................................................14
5.0
RECOMMENDATIONS......................................................................................................................15
5.1
Maintenance .......................................................................................................................................15
5.2
Monitoring ..........................................................................................................................................16
5.3
Future Considerations ......................................................................................................................17
6.0
CONCLUSION ......................................................................................................................................18
7.0
CLOSURE ...............................................................................................................................................19
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2014 Sediment Trap Assessment
List of Figures
Figure 1
Obed Mine Location
Figure 2
Sediment Traps ST1 and ST2A/B Locations
Figure 3
Sediment Trap 3 Location
List of Tables
Table 2.1
Sediment Trap Site Preparation
Table 2.2
Sediment Trap Construction
Table 2.3
Sediment Trap Tie-In and Flow Through
Table 3.1
Erosion Control Mix 600 PLS/m2
Table 3.2
Sediment Trap Silt Curtain Removal
Table 3.3
Fish Salvage Results
Table 4.1
Sediment Assessment
List of Appendices
Appendix 1
Sediment Trap As –Built Drawings
Appendix 2
2014 Water Quality Data
Appendix 3
2014 Sediment Trap Bathymetry Data
Appendix 4
Sediment Trap Inspection Form
Appendix 5
Photographs
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CVRI – Obed Mountain Mine
1.0
INTRODUCTION
1.1
Background
2014 Sediment Trap Assessment
On October 31, 2013 a release of water and sediment occurred at the Coal Valley Resources Inc.
(CVRI) Obed Mountain Mine (OMM) near Hinton, Alberta. Refer to Figure 1 for the location of
the OMM.
The release occurred at the Red/Green Pit on the OMM site and moved downhill to the Main
Tailings Pond (MTP). The release overtopped the MTP dam and moved downstream
approximately 27 km to the Athabasca River, picking up eroded natural materials from the
release path. Apetowun Creek was impacted as a result of the volume and velocity of water.
The heavier particles of the released sediment were contained within the headwaters of
Apetowun Creek while finer particles were carried onward to Plante Creek and into the
Athabasca River.
The Red/Green Pond contained surface runoff, groundwater, process water as well as solids
from the coal washing process. Approximately 670,000 cubic metres of water and sediment was
released from the pond.
During the operating life of the OMM, CVRI produced export quality thermal coal that was
beneficiated through a washing and drying process. No chemicals were used in the washing
and drying process; flocculants were used in the settling ponds to promote the settling of the
solid material from the water to allow for approved release of the water to the environment.
1.2
Sediment Trap Decision Process
The Environmental Protection Order, EPO 2013 CR/34, issued by Alberta Environment and
Sustainable Resource Development (ESRD) stated:
Immediately take all steps to contain the mine wastewater solids (meaning sediments, coal fines
and any suspended solids or other Substances in the mine wastewater) remaining in Apetowun
Creek and Plante Creek and prevent any of these solids from entering the Athabasca River.
In order to minimise the post incident re-entry of deposited solids into the Athabasca River
during spring freshet or a significant precipitation event, it was determined that a series of
sediment traps installed on Apetowun Creek could recover deposited sediment that had
remobilised and could eventually reach Plante Creek and the Athabasca River.
The decision process for the need and location of the sediment traps was based on information
gathered during the assessments completed by OMM staff and environmental and engineering
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2014 Sediment Trap Assessment
consultants. A biophysical assessment of the entire release pathway was completed by
Millennium EMS Solutions Ltd. (MEMS) in November 2013.
The sediment traps and related access required approval of the:
•
Solids Recovery Plan, Clause 6 EPO 2013 CR/34 - Alberta Energy Regulator (AER);
•
Water Act and Public Lands Act - Environment and Sustainable Resource Development
(ESRD);
•
Fisheries Act - Department of Fisheries and Oceans Canada (DFO); and
•
Road Use, Crossing and Access Agreements - West Fraser, Shell Canada and CNRL.
Following is the justification breakdown for each sediment trap:
•
ST1: The trap location was chosen because of the proximity to existing access (DX
Road), stream channel morphology and the surrounding level of disturbance. Also the
original Apetowun Creek channel downstream of the DX Road crossing and the DX
culvert crossing was damaged during the release. The trap was initially designed to be
built off-stream but as the DX culvert required replacement and realignment the trap
design was modified to have Apetowun Creek flow through the trap.
•
ST2A/B: Two adjacent sediment traps (ST2A and ST2B) were proposed at this location.
The traps were designed to be constructed off-stream. The location was chosen based on
the proximity to existing access (Shell lease road), stream channel morphology and the
proximity (downstream) of the major disturbance areas.
•
ST3: The two cell trap was designed to be built off-stream. This location was chosen
based on the proximity to existing access (CNRL lease road), stream channel
morphology and proximity to the confluence of Plante Creek and the Athabasca River.
Prior to construction, CVRI received approval from ESRD on the locations and designs of the
sediment traps as well as Temporary Field Authorizations (TFAs) for the access, site activities
and construction of the sediment traps. Renewals of the TFA’s have been received for the
2015 season.
2.0
SEDIMENT TRAP DESIGN AND CONSTRUCTION
All activities undertaken for the construction of the sediment traps were overseen by an
environmental monitor who ensured that all personnel on site followed proper procedures to
limit the disturbance area and if conditions changed halted the work. All instream works were
supervised by a Qualified Aquatic Environment Specialist (QAES).
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2.1
2014 Sediment Trap Assessment
Sediment Trap Design
Matrix Solutions (Matrix) was retained to design the sediment traps and to provide construction
monitoring. The as-built design drawings are provided in Appendix 1. Design considerations
for the sediment traps were as follows:
•
The traps will be constructed off-channel, where possible, to minimise impacts to the
existing creek bed and to minimise the need for future modifications to allow fish
passage.
•
Minimising disturbance for the trap will be achieved by an appropriate size and layout
design and prior to construction clearly establishing stripping/disturbance limits.
•
Once timber clearing and ground conditions are identified, the trap location and
configuration may be modified to best fit the terrain and site-specific conditions.
•
ST1 and ST2A/B have been designed to settle particles up to the 1:10 year flow. In the
case of ST2A, flows beyond the 1:10 year design flow will overtop the diversion rock
structure and flow through the original creek channel.
•
Due to the significantly larger drainage area (and therefore, peak flows), ST3 would
require an unfeasibly large trap surface area and disturbance to riparian vegetation to
settle the design particle at the 1:10 year design flow. Therefore, ST3 was designed to
settle the design particles up to the maximum June flow of 5.70 m³/sec. The inlet sill is
set so that when the creek flows are greater than 0.3 m3/sec part of the creek flow
commenced passing into the trap.
•
The traps will feature a riprap protected inlet area with boulders to promote mixing at
the upstream end of the trap and a 1.5 m high rock overflow weir at the downstream
end.
•
The typical trap excavation will be approximately 2 m to provide for 1.5 m of settlement
storage.
•
Side slopes will be typically excavated at 2H:1V to be stable. Flatter slopes or overexcavation of unstable silt material may be required depending upon site-specific
materials encountered.
•
Flatter slopes at the inlet and outlet of the trap will be created to ensure these aren’t
barriers to fish passage.
As described in Appendix 1, the trap design allows for flexibility in operation and ease of
modification to facilitate fish passage. AER, DFO and ESRD approvals will be sought for
sediment trap decommissioning.
2.2
Site Preparation
Timber and soil conservation activities were completed during the preparation of the trap sites.
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2014 Sediment Trap Assessment
Site preparation included:
•
minimising the footprint; minimising the disturbance footprint of the trap was achieved
by appropriate sizing of the trap and layout of the design prior to construction to clearly
establish stripping/disturbance limits;
•
timber clearing; clearing included the salvage of merchantable timber and the mulching
of non-merchantable timber. Merchantable timber was decked on site and was
subsequently removed by West Fraser;
•
design modifications; once the timber was cleared and ground conditions were assessed,
the trap location and configuration will be modified to best fit the terrain and the actual
creek channel location; and
•
reclamation materials; topsoil and overburden material will be salvaged and stockpiled
separately to allow for future reclamation.
Table 2.1 outlines the timing of the site preparation for each sediment trap:
Table 2.1
Sediment
Trap
2.3
Sediment Trap Site Preparation
Clearing
Soil Salvage
ST1
February 26 – March 12, 2014
March 13 -15, 2014
ST2A
February 24 – March 3, 2014
March 4 – March 6, 2014
ST2B
February 19 – February 21, 2014
February 22 – March 2, 2014
ST3
February 3 – February 7, 2014
February 8 – February 12, 2014
Construction
After site preparation the excavation of the sediment traps was completed. The rough
excavation was based on the engineered drawings and was field fit as required to conform to
existing terrain features.
The engineered drawings provided the slope angles, depths, inlet and outlet elevations, as well
as the rock armoring specifications. Limestone from the Cadomin Quarry was used at the inlet
and outlets of all the sediment traps to protect the traps from erosion as velocities would be the
highest at these locations. The limestone was also strategically placed in the bottom of the
sediment traps along with root balls and logs to create fish habitat features. Four inch minus
round rock sourced from the Obed Mountain Gravel Pit, was used to supplement the limestone
within the traps and at strategic locations at the inlet and outlets. The placement of rock armour
was supervised by the on-site QAES and Matrix engineering monitor to ensure that erosion
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2014 Sediment Trap Assessment
potential was minimised and fish passage could be maintained through the constructed
features.
The construction of the sediment traps required in-stream work which was supervised by a
QAES. The QAES sampled locations upstream and downstream of the sediment traps prior to
construction to determine baseline water quality levels. Water sampling locations surrounding
the construction site were chosen by the QAES based on ice conditions and safety protocols.
Turbidity sampling was completed during in-stream work and if the turbidity readings
increased more than 25 NTU over the background, operations were suspended in order to
maintain the CCME Guidelines.
An as-built survey was completed once the sediment traps were fully constructed for the
development of the as-built drawings (Appendix 1).
Table 2.2 outlines the construction schedule for each sediment trap:
Table 2.2
Sediment Trap
2.4
Sediment Trap Construction
Construction
ST1
March 16 – April 7, 2014
ST2A
March 7 – March 19, 2014
ST2B
March 3 – March 15, 2014
ST3
February 13 – February 24, 2014
Trap Tie-In
Once the excavation of the sediment traps was finished a survey was completed to provide the
elevations and information to allow for the sediment traps to be tied into Apetowun Creek.
Installation of the trap inlet and outlet structures was supervised by a Matrix engineering
construction monitor.
Prior to excavation work the sediment trap was isolated from Apetowun Creek by installing
cofferdams constructed with one cubic metre and regular sand bags. The tie-in work was in
close proximity of the creek requiring supervision by the QAES, environmental monitors and
construction supervisors.
The outlet and inlet structures were the last features to be completed on the sediment traps.
Once these features were completed the cofferdam at the inlet was slowly breached to allow the
filling of the sediment trap.
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2014 Sediment Trap Assessment
During these activities the QAES monitored the work and collected water turbidity readings in
order to maintain surface water quality as described in Section 2.3. The traps were filled slowly
to keep turbidity levels within water quality guidelines and to allow for any sediment and
material associated with the construction of the sediment traps to settle out in the trap. A small
3” pump was used to wash the rock used in the construction of the sediment trap to ensure that
sediment would not be mobilised into Apetowun Creek.
Each sediment trap design was based on the proposed location of the trap and the creek
morphology. The following design features relating to the natural creek flow for each trap were
implemented (also shown in Appendix 1):
•
ST1: Due to the extensive damage to the section of Apetowun Creek immediately
downstream of the DX Road crossing it was decided to abandon the damaged section of
channel. The damage sustained during the release event to the DX Road culvert
required the replacement and realignment of the culvert. The realignment of the new
culvert allowed for a flow through design for ST1.
•
ST2A: The design required a small diversion dam, built from limestone blast rock and
sand bags, to be placed in the existing channel to redirect all the flow through ST2A.
Prior to the placement of the dam the section of creek that was to be abandoned was
isolated and electrofished. The original channel is still intact allowing for future use if
reclamation of the sediment trap is determined to be the best option.
•
ST2B: The design required a similar diversion dam to the one used at ST2A. The dam
redirects all flow through ST2A and leaves a section of the existing channel intact. The
existing channel section is much smaller in length compared to ST2A and does contain
some backwater flows providing additional fish habitat. This old channel can easily be
reconnected for future use if reclamation of the sediment trap is determined to be the
best option.
ST3: Due to the significantly larger drainage area (and therefore, peak flows), ST3
would require an unfeasibly large trap surface area and disturbance to riparian
vegetation to settle the design particle at the 1:10 year design flow. ST3, therefore, was
designed to settle the design particles up to the maximum June flow of 5.70 m³/s. In
order to achieve this a few larger limestone boulders were placed in Apetowun Creek to
direct some flow towards the trap and the inlet was raised to the appropriate elevation
for the maximum June flow. The construction of the inlet and outlet structures was
supervised by the Matrix engineering monitor to ensure that the trap was functioning as
designed. The timing associated with the eventual flow through of the trap is provided
in Table 3. Apetowun Creek continues to flow throughout the entire year in the original
channel making the reclamation of ST3 a practical option in the future. Due to the
design of this trap with flow through only in high water events, a fish salvage and pump
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2014 Sediment Trap Assessment
out of this trap is required in the fall to avoid fish being trapped in the sediment trap
over the winter.
Table 2.3 outlines the timing of the tie-in and flow through for each sediment trap:
Table 2.3
Sediment
Trap
Sediment Trap Tie-In and Flow Through
Tie- In and Filling
Flow Through
ST1
April 8, 2014
April 12, 2014
ST2A
March 20, 2014
April 2, 2014
ST2B
March 16, 2014
March 17, 2014
ST3
February 25, 2014
April 2, 2014
Downstream flow was maintained during the trap tie-in and filling through controlling the
filling rate and by supervision by Project personnel.
3.0
OPERATIONS & MAINTENANCE
3.1
Vegetation
After the sediment traps were constructed, the surrounding disturbed land received
revegetation applications. Live willow staking was completed along the slopes of each trap.
Willows were cut in the surrounding region at a length of approximately 3 feet allowing for the
stake to be trimmed once planted. Planting consisted of driving the stakes into the ground to a
minimum of 6 inches but deeper if ground conditions allowed. Willow stakes were planted at
an approximate density of 4 per square metre along the littoral zone of the traps and at a
density of approximately 2 per square metre closer to the crown of the trap slope.
White spruce seedlings were planted at a density of approximately 2,500-3,000 stems per
hectare throughout the disturbance area and also included some of the areas associated with the
sediment traps and the laydown areas that were used during construction.
An ESRD approved native erosion control mix was seeded along the disturbed areas around
each sediment trap to promote re-vegetation. The erosion control seed mix was applied at a
rate of 30kg/ha. Table 3.1 lists the ESRD approved erosion control seed mix that was used
around the sediment traps:
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Table 3.1
2014 Sediment Trap Assessment
Erosion Control Mix 600 PLS/m2
Species
3.2
Percent
Composition (%)
Percent by
Weight (%)
Kg/ha
Canada wild rye
40
68
9.6
Alkali bluegrass
40
7
1.04
Northern wheatgrass
20
25
3.53
Total
100
100
14.17
Erosion Control
CVRI implemented many mitigation control materials which included jute matting, soil lynx
(soil stabiliser), silt fencing, straw bales, seeding, willow staking and tree planting. Ongoing
monitoring and maintenance of these features will be essential in maintaining trap
effectiveness.
3.3
Silt Curtains
The purpose of the traps is to capture elevated levels of suspended solids in the creek flow that
is generated by the damage to the creek and the subsequent remediation work. The
performance of the traps is enhanced with the installation of suspended silt curtains. The silt
curtains consisted of jute material that is treated with an anionic polymer that causes the
suspended solids to bind to the jute curtain.
Based on field observations and communications with various groups and agencies, concerns
were raised that ice may damage the curtains which could result in the remobilisation of the
captured sediment. It was determined that the most appropriate course of action in terms of Silt
Curtains was to remove them for the winter season. In addition to the potential for sediment
remobilisation, there were concerns that the current curtain configuration could be a barrier to
fish passage.
Following are details on the removal of the silt curtains from each sediment trap. Fish salvage
was completed prior to any work that would isolate the traps:
ST1: The six silt curtains in ST1 were removed when the pump around diversion was in place
for the DX Culvert cleanout work (August 1-3, 2014). The pump around encompassed ST1 fully
isolating it from the creek flows. During the removal it was found that the manipulation of the
curtains caused captured sediment to release from the curtains into the trap. The by-pass was
maintained until the water quality in the trap was suitable for release. The lessons learned at
ST1 were applied to the curtain removals for ST2 and ST3.
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ST2A: A pump around diversion was not required as the diversion dam was manually opened
to allow the flow to bypass the trap in the original channel. A cofferdam was installed at the
inlet to isolate the trap. As an additional layer of protection for the creek, a temporary boom
was installed at the outlet to minimise turbid water leaving the trap. The six silt curtains were
floated to the bank and pulled up on shore. The diversion dam was reinstalled and the
cofferdam was removed and flow through the trap resumed.
There was a minor non-compliance with the Fishery Protection Plan (Pisces, 2013) during the
work. During the work the turbidity levels downstream of ST2A were compared to
background turbidity levels taken at a control site upstream of the trap. As detailed in the plan
when background turbidity levels are less than 250 mg/L a maximum increase of 25 mg/L above
background is allowed. When the diversion dam was removed the flows through the original
channel disturbed deposited sediment in the channel. The ST2A monitoring indicated a minor
exceedance of the allowable turbidity limit. As per the plan, the work was suspended for
approximately ½ hour until the flows returned to background turbidity levels.
ST2B: For the removal of the six silt curtains at ST2B a 6” pump was installed for the pump
around diversion. A suitable fish screen for the pump was not available so the pump sump
area was isolated with fish nets. The sump area was electrofished prior to installing the
cofferdam and pump. Two Spoonhead sculpin were removed from the pump sump area and
were transferred to the creek. A temporary sandbag cofferdam was installed at the trap outlet.
There were no non-compliances with the water quality objectives during the course of the work
at ST2B.
ST3: For the removal of the six silt curtains at ST3 a sandbag cofferdam was installed at the
inlet to isolate the trap. In order to maintain the trap isolation and to prevent fish was entering
the trap over the winter, the cofferdam has been left in place until flows resume in the spring.
Work commenced with the upper cell. As with ST2B there wasn’t a suitable fish screen
available for the pump so a pump sump was constructed with fish net. The pump sump area
was electrofished prior to installing the pump. The 6” pump was used to pump the upper cell
to the lower cell which had a temporary boom was installed at the outlet. A 3” pump was used
to pump a portion of the water to a vegetated area away from the creek. Once the water level
was pumped down the cell was electrofished and the curtains were removed.
When the work was completed on the upper cell the 6” pump was relocated to commence
pumping the lower cell into the upper cell. The lower cell was pumped down sufficiently to
allow a boat mounted electrofisher to be used. As it worked out, the volume of water pumped
from the lower cell completely filled the upper cell.
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2014 Sediment Trap Assessment
The work on ST3 was completed without a non-compliance with the fisheries protection plan.
Table 3.2 outlines the timing of the silt curtain removal for each sediment trap:
Table 3.2
Sediment Trap
Sediment Trap Silt Curtain Removal
Silt Curtain Removal
ST1
August 2, 2014
ST2A
October 21, 2014
ST2B
October 22, 2014
ST3
October 23, 2014
The depleted curtains were disposed of in the OMM Red Pit backfill. The curtain floats were
stored at the OMM for re-use.
It is planned to reinstall the curtains prior to freshet in the spring of 2015. While there were no
indications that the curtains impeded fish passage it is planned to install the curtains in a
staggered pattern to ensure positive fish passage.
3.4
Sediment Removal
The weekly trap inspections did not identify the need to clean out the sediment traps in 2014.
Bathymetric monitoring will continue to determine when the traps need to be cleaned out. It is
anticipated that accumulated sediment will be removed from the sediment traps in 2015.
The new DX Road culvert functioned as a pre-settling cell for ST1 and filled with sediment. The
accumulated sediment required removal on August 1-3, 2014. A pump around diversion was
put in place for the cleanout work. The pump around encompassed ST1 fully isolating it from
the creek flows. Approximately 190 m3 of sediment was recovered during the cleanout and this
material was disposed of in the OMM Red Pit backfill.
3.5
Fish Salvage
ST3 is a partial flow through trap where only a proportion of the total creek flow passes
through the trap at peak flow times as mentioned above. As flows during the winter will be
below the inlet height the trap will isolate and may not retain a sufficient water depth to
overwinter a resident fish population. It was decided that, in conjunction with the curtain
removal, that a fish salvage program would be completed on ST3.
A fish salvage program was completed on the pump around diversion sump used at ST2B
when the silt curtains were removed.
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2014 Sediment Trap Assessment
Table 3.3 provides a summary of the results of the fish salvage completed at ST2B and ST3.
Table 3.3
Fish Salvage Results
Species
Number
Spoonhead sculpin
294
Rainbow trout
39
Brook trout
2
Mountain whitefish
18
Burbot
7
Total Fish Salvaged
360
The fish salvage work was completed under the direct supervision of a QAES.
4.0
MONITORING
4.1
Water Quality
Surface water quality monitoring was a major component of the OMM release remediation
work. Daily water samples were taken from various locations along Apetowun Creek, Plante
Creek and the Athabasca River. In order to continuously monitor the water quality in
Apetowun and Plante Creeks and the Athabasca River, a series of data sondes were installed in
these watercourses.
Turbidity is used to measure the effectiveness of the sediment traps. Information from the data
sondes was used in determining the effectiveness of the sediment traps. The following data
sondes were used for the trap analysis:
•
APC: located within Apetowun Creek directly upstream of ST1 (approximately 150m
upstream of the DX Road culvert inlet).
•
APC-DS: located within Apetowun Creek between ST2B and ST3.
•
PLC-US: located on Plante Creek approximately 100 m upstream of the
Apetowun/Plante confluence.
•
PLC-DS: located within Plante Creek approximately 100 m upstream of the Emerson
Road bridge.
Appendix 2 contains the water quality data from the various data sondes upstream and
downstream of the sediment traps. Two tables (Appendix 2) were generated showing the
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2014 Sediment Trap Assessment
turbidity at the APC and APC-DS datasondes. The tables illustrate the positive effects that the
traps are having on downstream water quality.
4.2
Sediment Trap Inspections
Project staff visually inspected the sediment traps on a daily basis. Scheduled weekly sediment
trap inspections were completed from the end of May to freeze-up (mid-November, 2014). The
inspections involved a visual inspection and filling out an inspection form which contained a
number of variables (date, time, precipitation in the last 24 hours, weather conditions, staff
gauge readings, water sample results, slope stability, inlet and outlet structures) and the
identification of potential problems. An example of the sediment trap inspection form can be
found in Appendix 4.
4.3
Bathymetry Data
A bathymetric survey of the sediment traps was completed on July 28 and 29, 2014. The results
of the survey were compared to the as-built surveys that were completed when the traps were
constructed. The assessment results are summarised in Table 4.1.
Table 4.1
Sediment Assessment
Design Storage
Capacity (m3) (1)
Current
Sediment
Accumulation
(m3)
ST1
360
407
113
1.51
410
ST2A
144
143
99
1.16
238
ST2B
773
715
92
0.9
0
ST3 - Cell 1
432
319
74
0.93
0
ST3 - Cell 2
368
268
73
1.05
88
Trap
% Full (2)
Maximum
Additional
Storage (m3)(4)
Average
Depth (m) (3)
(1) based on 1 m depth of sediment in bottom
(2) column 2/column 1
(3) computed based on bathymetric survey of volume/surface area
(4) surface area (reduce by 10%) times average depth greater than 0.9m
Table 4.1 shows that as of July 29, 2014 an estimated 1850 m3 of sediment has been captured by
the sediment traps. The table also shows that when compared to the 1 m storage depth (total
trap depth is 2 m) the traps are filling with accumulated sediment and that ST1 and ST2B both
require sediment removal early in 2015.
Appendix 3 contains the bathymetry data including figures for each of the sediment traps.
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5.0
RECOMMENDATIONS
5.1
Maintenance
2014 Sediment Trap Assessment
The 2015 maintenance tasks will depend on the results of the ongoing monitoring and sediment
accumulation assessments.
The 2014 bathymetry data analysis indicated that all of the traps are nearing their design
storage capacity and that ST1 and ST2B need to have the sediment removed early in 2015.
While the traps will continue to provide value their performance will degrade if the sediment is
not removed in 2015:
•
It is recommended that ST1 and ST2B be scheduled for sediment removal in Q2 2015.
The need to dredge ST2A and ST3 will depend on the decision regarding their ultimate
fate. If it is determined that the two traps will be reclaimed in 2015 there is no
requirement to remove the sediment from the traps prior to reclamation.
•
A detailed work plan for the removal of sediment from ST1 and ST2B will be developed
in March/April 2015.
It would be of value to determine if sediment deposited during the event is still mobilising:
•
It is recommended that solids samples be taken in the spring from each of the sediment
traps in order to analyse the deposited material and compare it to the natural soil
samples and solids samples that were taken in 2014. This comparison will allow for the
determination of what material is being collected by the sediment traps– released solids
or natural soils.
In 2014, silt curtains were placed in each sediment trap cell to enhance the capture of suspended
solids. The curtains were removed in the fall of 2014:
•
It is recommended that in 2015 the silt curtains be redeployed into all of the sediment
traps in the period between ice-off and spring freshet. In 2014, the curtains were
installed across the trap which caused fish passage concerns. When the curtains are
installed in 2015, the silt curtains will be placed in a staggered pattern ensuring positive
fish passage.
The 2014 inspections noted a small slope stability issue on the northern slope of ST2A. The
slump has been monitored and appears to have stabilised.
•
It is recommended that the slope be monitored in 2015 and if further movement is
documented a remedial plan be developed to stabilise the slope.
March 2015
15
CVRI – Obed Mountain Mine
2014 Sediment Trap Assessment
The sediment trap areas were seeded with native seed mixes and planted with live willow
stakes and spruce seedlings:
•
It is recommended that the sediment trap areas be included in the 2015 vegetation
assessment to determine if further seeding of the erosion control mix is required as well
as to determine the success rate of the willow and white spruce planting and to
determine if remedial revegetation is required.
The incident and the subsequent remediation work have the potential to introduce undesirable
plant species:
•
It is recommended that the vegetation assessment include a weed survey to identify any
invasive weed species. If weed species are identified an appropriate weed control plan
will be developed and implemented. Weed control options could range from manual
removal to the application of an herbicide. Qualified weed control specialists will be
used to design and implement the weed control program.
During the remedial work in 2014, erosion control materials were installed to minimise erosion.
A combination of jute matting, silt fence and straw bales were used to slow water movement to
the creek. The materials may have degraded over the winter and spring or may not provide the
coverage required:
•
It is recommended that the erosion control materials be inspected and be repaired,
replaced or extended as required.
•
It is recommended that the straw bales be either removed on spread out in situ.
It is not known at this time if the traps will be retained as permanent aquatic features or if they
will be removed:
•
5.2
It is recommended that a meeting be set up with the AER to discuss the plans for the
traps. The question is if the traps provide value as aquatic habitat and should be
retained as permanent features of if they should be taken out of service and reclaimed.
Monitoring
All of the sediment traps will be periodically inspected during the winter season to ensure there
are no major issues (debris, vandalism, wildlife concerns). In 2014, a weekly documented
inspection was completed on each sediment trap:
•
It is recommended that a series of inspections occur in the spring of 2015 (prior to and
during freshet) to ensure the traps are functioning as designed.
March 2015
16
CVRI – Obed Mountain Mine
•
2014 Sediment Trap Assessment
It is recommended that the weekly inspections commence once the ice is off of the
sediment traps and continue until freeze up. The inspections will utilise the same
inspection form as 2014 with the inspector noting any flow concerns (debris, fish
passage), slope stability issues, vegetation problems (weeds, germination rates, tree
growth), surface water quality, access road condition, sediment accumulation and
general observations.
A bathymetric survey was undertaken in July 2014 to determine sediment accumulation in the
traps:
•
5.3
It is recommended that bathymetric surveys continue in 2015 and that the data is
analysed in a timely manner.
Future Considerations
The sediment trap monitoring frequency may be reduced to bi-monthly once vegetation has
further established and erosion materials are no longer required.
The need for silt curtains past 2015 may not be necessary as the vegetation of the disturbed
areas establishes.
During 2015, monitoring of the sediment traps will continue and information will be recorded.
This information will help determine the fate of the sediment traps. The sediment traps have
already proven to be viable fish habitat with the potential for overwintering. With a larger data
set the ability to determine if these sediment traps are functioning as sustainable ecosystems can
be made but these determinations will need to factor in future maintenance issues and the land
use in the region. It would be of value to have an aquatic environment habitat specialist
undertake an assessment.
Reclamation considerations are provided below:
•
ST1: It is recommended that this sediment trap be maintained as it directly aligns with
the new DX Road culvert and full flow through the trap has been achieved. This
sediment trap is and should continue to provide excellent habitat, including
overwintering, on the upper reaches of Apetowun Creek. If the decision is made to
retain the trap as a permanent feature the access road to the sediment trap could be
reclaimed. As the heavily damaged section of channel was backfilled during the
construction of the trap the intention is that the trap will be retained as a final landscape
feature.
•
ST2A: It is recommended that the decision on the end use of this sediment trap be
further reviewed as the overwintering potential is high and the possibility of
maintaining flow through the original channel and the trap is feasible with minor
March 2015
17
CVRI – Obed Mountain Mine
2014 Sediment Trap Assessment
modifications at the inlet and outlet of the trap. The original channel is fully intact so if
it is decided to remove this trap the creek flow would be redirected in the original
channel. If the trap is reclaimed the access road would also be reclaimed.
•
ST2B: It is recommended that this sediment trap be maintained as it provides new fish
habitat opportunities including overwintering habitat. The remnant channel still
provides backwater pool habitat for fish species and with minor modifications water
levels in this backwater pool could be increased. The access road to the sediment trap
could be reclaimed.
•
ST3: It is recommended that ST3 be reclaimed. The trap requires year round
maintenance and is located remotely from the OMM. In addition, due to the design the
trap only receives flow during peak flow periods which can lead to the trap isolating
during low flow periods. Isolation of the trap could lead to fish kills in the winter due to
low oxygen levels and freezing to the bottom. When reclaiming the trap the excavation
will be backfilled, soil materials replaced and the site will be revegetated. In addition,
the access road would also be reclaimed.
The above recommendations for consideration are dependent on how the traps perform in 2015
and the requirement for such mitigation features in the future.
6.0
CONCLUSION
Overall, the sediment traps were deemed effective in 2014 by functioning as to their design and
successfully capturing remobilised suspended solids. Based on the bathymetry survey and
assessment, an estimated 1,850 m3 of solids has been captured within the sediment traps,
material that otherwise would have deposited within Apetowun Creek, Plante Creek or the
Athabasca River.
March 2015
18
CVRI – Obed Mountain Mine
7.0
2014 Sediment Trap Assessment
CLOSURE
Should you have any questions, please contact Kari McDonald at (780) 420-5866.
Yours truly,
Millennium EMS Solutions Ltd.
Prepared by:
Al Watson, C.E.T.
Senior Project Manager
Reviewed by:
Andy Etmanski
EVP Mining
March 2015
19
CVRI – Obed Mountain Mine
2014 Sediment Trap Assessment
FIGURES
March 2015
I
T56
T55
T54
³
²
748
Pinedale
Edson
16
Ri
Obed
sc
a
a
ab
Ath
T52
"
³
²
Obed
Mine
ver
T53
M cLeo
d
Rive r
T51
47
Hinton
³
²
³
²
40
"
Erit h
Entrance
er
Em
ba
rr
as
Riv
r
ve
Ri
T50
T49
Gregg
River
Mine
er
Luscar
Mine
Plant
Site
Luscar "
T47
Riv
Miette
Hotsprings
Document Path: K:\Active Client\CVRI\Final Docs\14-00001\Sed Trap Assessment\2015\Fig 1 Project Location.mxd
Coal Valley
Mines
Mercoal "
³
²
T48
" Robb
40
m
Pe
"
)
bin
a
" Cadomin
T46
Jasper
National
R24
Park
R23
Cheviot Mine
R22
R21
R20
R19
R17
R18
R16 W5M
T45
Legend
Obed Mine Permit Boundary
Other Mines
0
5
10
20 km
1:550,000
Disturbance Footprint
Area of
Detail
Edmonton
Obed Mountain Mine
Calgary
TITLE:
Lethbridge
Project Location
DRAWN:
JG
CHECKED: AW
DATE:
Mar 9/15
PROJECT:
14-00001
FIGURE:
1
I
j
k
35
53-24 W5M
APC-DS
36
53-24 W5M
Sh
el
lR
oa
d
Sediment Trap 2b
Sediment Trap 2a
26
53-24 W5M
Apet
o
wun
C
re e k
31
53-23 W5M
25
53-24 W5M
Document Path: K:\Active Client\CVRI\Final Docs\14-00001\Sed Trap Assessment\2015\Fig 2 Sediment Trap 1 and 2 AB.mxd
_
^
D/
X
23
53-24 W5M
R
30
53-23 W5M
Blowout
oa
d
j
k
APC
24
53-24 W5M
Sediment Trap 1
19
53-23 W5M
Legend
TFA Boundary
ek
e
Remediation Disturbance
Limit
Cr
Street
n
wu
eto
Ap (Geobase)
Hydrology
k
j
_
^
Data Sonde
Blowout
REF: CVRI Ltd. Mar 2009; Geogratis; Geobase; Airborne Imaging, 2014.
0
100
200
1:9,000
Obed Mountain Mine
400 m
TITLE:
Sediment Traps 1 and 2 A/B
DRAWN:
JG
CHECKED: AW
DATE:
Mar 17/15
PROJECT: 14-00001
FIGURE:
2
I
e Creek
14
54-23 W5M
j
k
13
54-23 W5M
18
54-22 W5M
17
54-22 W5M
12
54-23 W5M
7
54-22 W5M
8
54-22 W5M
PLC-US
11
54-23 W5M
Plan
te
Apeto
wun C
reek
Cree
k
Sediment Trap 3
es
cl
Ec
R
d
oa
2
54-23 W5M
1
54-23 W5M
6
54-22 W5M
5
54-22 W5M
e rs
Em
Document Path: K:\Active Client\CVRI\Final Docs\14-00001\Sed Trap Assessment\2015\Fig 3 Sediment Trap 3 to Athabasca River.mxd
35
53-23 W5M
36
53-23 W5M
C
on
k
ree
ad
Ro
31
53-22 W5M
32
53-22 W5M
j
k
26
53-23 W5M
25
53-23 W5M
30
53-22 W5M
s
Athaba
e
ca Riv
PLC-DS2
r
29
53-22 W5M
Legend
TFA Boundary
Obed Mountain Mine
Remediation Disturbance Limit
Street
Hydrology (Geobase)
j
k
Data Sonde
REF: CVRI Ltd. Mar 2009; Geogratis; Geobase; Airborne Imaging, 2014.
0
0.2
0.4
1:18,000
0.8 km
TITLE:
Sediment Trap 3 to Athabasca River
DRAWN:
JG
CHECKED: AW
DATE:
Mar 17/15
PROJECT: 14-00001
FIGURE:
3
CVRI – Obed Mountain Mine
2014 Sediment Trap Assessment
APPENDIX 1: SEDIMENT TRAP AS-BUILT DRAWINGS
March 2015
Easting (m)
467000
468000
469000
470000
471000
472000
473000
474000
475000
476000
477000
478000
479000
480000
481000
482000
484000
485000
5945000
5944000
5943000
5943000
5944000
5945000
5946000
reek
5946000
Plante C
483000
reek
5942000
5939000
5940000
5941000
5942000
5939000
5940000
5941000
Northing (m)
wun C
Apeto
ek
re
C
ge
r
Ro
ter
Cr
ee
k
467000
468000
469000
470000
471000
472000
473000
474000
475000
476000
477000
478000
479000
480000
481000
482000
483000
484000
485000
1:50000
500
Stamp
Revision
5937000
5937000
Ath
aba
sca
Riv
5938000
er
os
5938000
Go
Meters
0
500
UTM83-11
1000
Westmoreland Coal Company
Drainage Area
Road
Location Plan
Road - Light Use
Trail
Disclaimer: The information contained herein may be compiled from numerous third party materials that are subject to periodic change
without prior notification. While every effort has been made by Matrix Solutions Inc. to ensure the accuracy of the information presented at
the time of publication, Matrix Solutions Inc. assumes no liability for any errors, omissions, or inaccuracies in the third party material.
Permit to Practice
P5540
0
July 7, 2014
No.
Date
Date:
Issued Final
Description
Project:
July 2014
5821-OB-SC-14
Technical:
KC
By
Reviewer:
K. Curtis
Drawn:
D. Cooper
Z. Steele
Obed Mountain Mine Apetowun Creek Sediment Control Traps
Figure
1
Modifications to Conceptual Design to:
Accomodate actual location of creek, which differed significantly
from LiDAR used for conceptual design
Accomodate the longer replacement culvert, which is larger
diameter and countersunk to provide fish passage.
Provide fish passage through sediment trap (not included on
conceptual design)
Backfill remnant creek channel that was heavily damaged during
Oct. 31, 2013 events. This increases trap stability during a flood
event.
Major Contour (2m) - LiDAR (Date unknown)
1:500
Site Plan
Rounded Riprap (Brown)
5
Meters
0
5
10
UTM83-11
Minor Contour (0.5m) - LiDAR (Date unknown)
Angular Riprap (Grey)
Conceptual Design (December 2013) Based on LiDAR
Mixed Riprap
As-Built Survey (Foothills Survey Ltd. May 29, 2014)
Jute Matting
Coconut Matting
Access Road
Water Surface
Notes:
1. Fish passage maintained through sediment trap.
2. See site photographs 1 and 2 on Figure 8.
3.
conceptual design)
4. During a flood, the floodplain south of the sediment trap will be inundated,
mimicking natural flood conditions.
5. Refer to the inspection form for monitoring requirements.
6. Water surface in plan view estimated from survey data for illustration purposes.
Disclaimer: The information contained herein may be compiled from numerous third party materials that are subject to periodic change
without prior notification. While every effort has been made by Matrix Solutions Inc. to ensure the accuracy of the information presented at
the time of publication, Matrix Solutions Inc. assumes no liability for any errors, omissions, or inaccuracies in the third party material.
Reference: Contour lines based on 2m LiDAR provided by Coal Valley Resources Inc.
Creek survey data based on January 25, 2014 and May 29, 2014 survey by Foothills Surveys Ltd.
Stamp
Revision
Westmoreland Coal Company
Sediment Trap 1 (ST1)
As-Built Site Plan
Permit to Practice
P5540
0
July 7, 2014
No.
Date
Date:
Issued Final
Description
Project:
July 2014
5821-OB-SC-14
Technical:
KC
By
Reviewer:
K. Curtis
Drawn:
D. Cooper
Z. Steele
Obed Mountain Mine Apetowun Creek Sediment Control Traps
Figure
2
1
1272
1272
1270
1270
Sediment Trap 1
1268
1268
Floc Block
B
-
1264
1264
1262
1262
Trap Inlet
10.7 m @ 6.5%
0+010
0+020
0+030
0+050
1
1
1268
1266
1266
1
2.5
0+060
Surveyed Water Level
(May 29, 2014)
1
3
0+070
Trap Outlet
16.8 m @ 5.0%
Trap
53.8 m
0+080
0+090
0+100
0+110
0+120
Profile
0+130
0+140
0+150
1260
0+155
C
Horizontal Scale 1:500
Vertical Scale 1:125
Elevation (m)
1268
0+040
1266
Elevation (m)
1260
0+000
Elevation (m)
1266
C
1266
Surveyed Water Level
(May 29, 2014)
1
1
3
1264
3
1264
Rock Plug
Elevation (m)
1266
-
-
Surveyed
Water Level
(May 29, 2014)
Elevation (m)
Elevation (m)
A
Jute Curtains
1.3 m
1264
0+000
1264
0+010
Trap Inlet
C
1
Scale 1:100
B
Trap Outlet and Rock Plug
Scale 1:100
1270
1270
Jute Matting
Elevation (m)
1268
Jute Matting
1268
Access Road
1266
1264
1266
1
2
Surveyed Water
Level (May 29,
2014)
2
1
1264
1262
1260
0+000
1262
0+010
0+020
0+030
B
1
Notes:
1. Fish passage maintained through sediment trap.
2. See site photographs 1 and 2 on Figure 8.
3.
conceptual design)
4. During a flood, the floodplain south of the sediment trap will be inundated,
mimicking natural flood conditions.
5. Refer to the inspection form for monitoring requirements.
Disclaimer: The information contained herein may be compiled from numerous third party materials that are subject to periodic change
without prior notification. While every effort has been made by Matrix Solutions Inc. to ensure the accuracy of the information presented at
the time of publication, Matrix Solutions Inc. assumes no liability for any errors, omissions, or inaccuracies in the third party material.
1262
0+020
0+010
Elevation (m)
A
1
1262
0+000
Reference: Contour lines based on 2m LiDAR provided by Coal Valley Resources Inc.
Creek survey data based on January 25, 2014 and May 29, 2014 survey by Foothills Surveys Ltd.
0+040
0+050
1260
0+060
Sediment Trap 1
Scale 1:250
Stamp
Revision
Westmoreland Coal Company
Sediment Trap 1 (ST1)
As-Built Profile and Sections
Permit to Practice
P5540
0
July 7, 2014
No.
Date
Date:
Issued Final
Description
Project:
July 2014
5821-OB-SC-14
Technical:
KC
By
Reviewer:
K. Curtis
Drawn:
D. Cooper
Z. Steele
Obed Mountain Mine Apetowun Creek Sediment Control Traps
Figure
3
Sediment Trap 2A
Sediment Trap 2B
Modifications to Conceptual Design to:
Accomodate actual location of creek, which differed significantly
from LiDAR used for conceptual design
Provide setback from CNRL ROW PLA070982
Minimize cut and maximize sediment trap capacity based on site
conditions
Provide fish passage (not included on conceptual design)
Modifications to Conceptual Design to:
Accomodate actual location of creek, which
differed significantly from LiDAR used for
conceptual design
Provide fish passage (not included on
conceptual design)
Major Contour (2m) - LiDAR (Date unknown)
Rounded Riprap (Brown)
Minor Contour (0.5m) - LiDAR (Date unknown)
Angular Riprap (Grey)
Conceptual Design (December 2013) Based on LiDAR
Mixed Riprap
As-Built Survey (Foothills Survey Ltd. June 1, 2014)
Jute Matting
1:750
Site Plan
7.5
Meters
0
7.5
UTM83-11
15
Access Road
Water Surface
Notes:
1. Fish passage maintained through sediment trap.
2. During a flood, the diversion dams at the inlets of ST2A and ST2B will be overtopped, and flood flows
will be conveyed in the natural creek channel. During extreme flood events, when the sediment traps
and natural channel are overtopped, the floodplain surrounding the sediment trap will be inundated,
mimicking natural flood conditions. When flood waters recede, flow will again be contained in the
sedmient trap. Minor repairs may be required to the trap inlets and diversion dam.
3.
Disclaimer: The information contained herein may be compiled from numerous third party materials that are subject to periodic change
without prior notification. While every effort has been made by Matrix Solutions Inc. to ensure the accuracy of the information presented at
the time of publication, Matrix Solutions Inc. assumes no liability for any errors, omissions, or inaccuracies in the third party material.
4.
5.
6.
Stamp
Westmoreland Coal Company
Sediment Trap 2A and 2B (ST2A and ST2B)
As-Built Site Plan
See site photographs 3 and 4 on Figure 8.
Refer to the inspection form for monitoring requirements.
Water surface in plan view estimated from survey data for illustration purposes.
Reference: Contour lines based on 2m LiDAR provided by Coal Valley Resources Inc.
Creek survey data based on January 25, 2014 and June 1, 2014 surveys by Foothills Surveys Ltd.
Revision
Permit to Practice
P5540
0
July 7, 2014
No.
Date
Date:
Issued Final
Description
Project:
July 2014
5821-OB-SC-14
Technical:
KC
By
Reviewer:
K. Curtis
Drawn:
D. Cooper
Z. Steele
Obed Mountain Mine Apetowun Creek Sediment Control Traps
Figure
4
1
1228
1228
140 m of Creek Bypassed
1226
1226
B
Elevation (m)
-
-
Trap Inlet
Surveyed Water Level
(June 1, 2014)
1224
-
1224
Jute Curtain
1222
1220
C
Trap Inlet
13.1m
@ 3.5%
1222
Trap Outlet
19.9m @ 2.0%
Trap
72m
1218
0+060
0+080
0+100
1
3
0+120
Profile
1220
1218
0+1600+165
0+140
Note:
Elevation (m)
A
The profile shown (0+060 to 0+165) here includes only those aspects
of the alignment that are relevant to Sediment Trap 2A.
Horizontal Scale 1:750
Vertical Scale 1:150
B
1224
Diversion
Dam
1222
0+000
1222
0+015
0+010
A
3
1226
1226
Surveyed Water Level
(June 1, 2014)
1
3
1224
1222
0+000
0+010
Trap Inlet
1
3
1224
1224
1
Surveyed Water Level
(June 1, 2014)
4
1222
Elevation (m)
1226
Elevation (m)
1226
1226
Elevation (m)
D
1228
Access Road
1224
1226
Natural Creek
(Backwater)
Surveyed Water Level
(June 1, 2014)
1224
1
3
6.5
1
1222
1222
1222
1220
0+000
1220
0+000
1222
0+025
Scale 1:200
C
1228
1224
0+020
B
3
Diversion Dam
Scale 1:200
1
3
0+010
0+020
0+030
C
3
Sediment Trap 2A
4.
5.
Trap Outlet
Scale 1:200
Scale 1:200
Notes:
1. Fish passage maintained through sediment trap.
2. During a flood, the diversion dams at the inlets of ST2A and ST2B will be overtopped, and flood flows
will be conveyed in the natural creek channel. During extreme flood events, when the sediment traps
and natural channel are overtopped, the floodplain surrounding the sediment trap will be inundated,
mimicking natural flood conditions. When flood waters recede, flow will again be contained in the
sedmient trap. Minor repairs may be required to the trap inlets and diversion dam.
3.
Disclaimer: The information contained herein may be compiled from numerous third party materials that are subject to periodic change
without prior notification. While every effort has been made by Matrix Solutions Inc. to ensure the accuracy of the information presented at
the time of publication, Matrix Solutions Inc. assumes no liability for any errors, omissions, or inaccuracies in the third party material.
D
3
1220
0+050
0+040
1220
0+020
0+010
Stamp
Revision
Westmoreland Coal Company
Sediment Trap 2A (ST2A)
As-Built Profile and Sections
See site photographs 3 and 4 on Figure 8.
Refer to the inspection form for monitoring requirements.
Permit to Practice
P5540
0
July 7, 2014
No.
Date
Date:
Issued Final
Description
Project:
July 2014
5821-OB-SC-14
Technical:
KC
By
Reviewer:
K. Curtis
Drawn:
D. Cooper
Z. Steele
Obed Mountain Mine Apetowun Creek Sediment Control Traps
Figure
5a
Elevation (m)
1224
1228
Elevation (m)
1226
Elevation (m)
Elevation (m)
1226
Elevation (m)
1228
1
1226
1226
31 m of Creek Bypassed
E
1224
-
Jute Curtains
G
-
1222
F
-
1220
1220
Trap Outlet
13.5 m
@ 0.3%
Trap
80.6 m
1218
E
1226
1218
1224
1224
Surveyed Water Level
(June 1, 2014)
1
1222
1222
3
Diversion Dam
Trap Inlet
5.9 m @ 2.2%
1216
0+290
1226
Elevation (m)
1222
Elevation (m)
Elevation (m)
Surveyed Water Level
(June 1, 2014)
Elevation (m)
1224
0+300
0+320
0+340
1
3
0+360
Note:
Profile
1220
0+000
1216
0+390
0+380
0+010
E
3
The profile shown (0+290 to 0+390) here includes only those aspects
of the alignment that are relevant to Sediment Trap 2B.
0+020
0+030
1220
0+034
Trap Inlet and Diversion Dam
Scale 1:200
Horizontal Scale 1:750
Vertical Scale 1:150
F
1222
Jute Matting
1222
Surveyed Water Level
(June 1, 2014) 1
3
1.5
1220
1218
0+000
1224
Jute Matting
0+010
1
Natural Creek
(Backwater)
0+020
0+030
F
3
0+040
0+050
1220
Elevation (m)
Elevation (m)
1224
1218
0+055
Sediment Trap 2B
Scale 1:200
G
1222
1224
Surveyed Water Level
(June 1, 2014)
1
4
1220
4.
5.
1218
0+020
0+010
G
3
Notes:
1. Fish passage maintained through sediment trap.
2. During a flood, the diversion dams at the inlets of ST2A and ST2B will be overtopped, and flood flows
will be conveyed in the natural creek channel. During extreme flood events, when the sediment traps
and natural channel are overtopped, the floodplain surrounding the sediment trap will be inundated,
mimicking natural flood conditions. When flood waters recede, flow will again be contained in the
sedmient trap. Minor repairs may be required to the trap inlets and diversion dam.
3.
1222
1220
1218
0+000
Disclaimer: The information contained herein may be compiled from numerous third party materials that are subject to periodic change
without prior notification. While every effort has been made by Matrix Solutions Inc. to ensure the accuracy of the information presented at
the time of publication, Matrix Solutions Inc. assumes no liability for any errors, omissions, or inaccuracies in the third party material.
1
3
Elevation (m)
Elevation (m)
1224
Trap Outlet
Scale 1:200
Stamp
Revision
Westmoreland Coal Company
Sediment Trap 2B (ST2B)
As-Built Profile and Sections
See site photographs 3 and 4 on Figure 8.
Refer to the inspection form for monitoring requirements.
Permit to Practice
P5540
0
July 7, 2014
No.
Date
Date:
Issued Final
Description
Project:
July 2014
5821-OB-SC-14
Technical:
KC
By
Reviewer:
K. Curtis
Drawn:
D. Cooper
Z. Steele
Obed Mountain Mine Apetowun Creek Sediment Control Traps
Figure
5b
Natural Creek Undisturbed by
Construction
Location of Apetowun Creek Based
on Survey Data (Foothills Survey
Jan. 25, 2014)
Assumed Location of Apetowun
Creek Based on LiDAR Data
0+175
D
0+000
6
n Cr
eek
6
0
0+00
C
E0
6
+0
0
0
0+
01
5
00
Ape
6
0+0
towu
B
0
0+15
0+100
A
0+
6
0
00
0+03
0
0+030
50
0+0
0+000
0+0
30
1
0+030
6
Major Contour (2m) - LiDAR (Date unknown)
Minor Contour (0.5m) - LiDAR (Date unknown)
Access Road
Conceptual Design (December 2013) Based on LiDAR
Water Surface
1:750
Site Plan
Riprap
7.5
Meters
0
7.5
UTM83-11
15
As-Built Survey (Foothills Survey Ltd. June 2, 2014)
Notes:
1. Fish passage maintained in creek.
2. Refer to the inspection form for monitoring requirements.
3.
4.
5.
Disclaimer: The information contained herein may be compiled from numerous third party materials that are subject to periodic change
without prior notification. While every effort has been made by Matrix Solutions Inc. to ensure the accuracy of the information presented at
the time of publication, Matrix Solutions Inc. assumes no liability for any errors, omissions, or inaccuracies in the third party material.
6.
Stamp
Westmoreland Coal Company
Sediment Trap 3 (ST3)
As-Built Site Plan
conceptual design)
See site photographs 5 to 8 on Figure 9.
During a flood, the majority of flows will be conveyed by the natural channel and
floodplain with some additional conveyance provided by the sediment trap.
Water surface in plan view estimated from survey data for illustration purposes.
Reference: Contour lines based on 2m LiDAR provided by Coal Valley Resources Inc. Creek survey data
based on January 25, 2014 and June 2, 2014 surveys by Foothills Surveys Ltd.
Revision
Permit to Practice
P5540
0
July 7, 2014
No.
Date
Date:
Issued Final
Description
Project:
July 2014
5821-OB-SC-14
Technical:
KC
By
Reviewer:
K. Curtis
Drawn:
D. Cooper
Z. Steele
Obed Mountain Mine Apetowun Creek Sediment Control Traps
Figure
6
1
1030
1030
Natural Creek
240 m of Creek Bypassed
1028
1028
Jute Curtains
-
1026
C
1026
-
Elevation (m)
B
Natural Creek
-
1024
1024
1022
Cell #1
60 m
Trap Inlet
11 m @ 0.1%
1020
Sill
6.3 m @ 0%
1018
0+020
0+040
0+060
0+080
1
5
1016
0+175
0+160
Profile
C
1024
1022
0+030
0+020
1024
1
1024
1
3
3
1022
1022
1020
0+000
0+010
1020
0+030
0+020
B
5
Natural Creek and Trap Inlet
Scale 1:300
Disclaimer: The information contained herein may be compiled from numerous third party materials that are subject to periodic change
without prior notification. While every effort has been made by Matrix Solutions Inc. to ensure the accuracy of the information presented at
the time of publication, Matrix Solutions Inc. assumes no liability for any errors, omissions, or inaccuracies in the third party material.
1020
1024
Elevation (m)
3
1018
0+030
0+020
1024
0+010
0+020
1022
0+030
Sill Between Cell #1 and Cell #2
Scale 1:300
1022
1020
1022
1020
6.4 m
1018
0+000
0+010
E
5
Cell #2
Stamp
1024
Surveyed Water Level
(June 2, 2014)
Scale 1:300
Notes:
1. Fish passage maintained in creek.
2. Refer to the inspection form for monitoring requirements.
3.
4.
5.
1022
3
D
5
1024
E
1
0+010
1026
C
5
Elevation (m)
Elevation (m)
1018
0+000
1026
Cell #1
1024
1
1020
1028
Scale 1:300
Surveyed Water Level
(June 2, 2014)
1022
1028
1022
0+000
D
1024
Elevation (m)
1026
1026
Surveyed Water Level
(June 2, 2014)
Elevation (m)
0+010
A
5
0+140
Elevation (m)
1
3
Trap Inlet
1026
Elevation (m)
Surveyed Water Level
(June 2, 2014)
1022
0+000
0+120
B
1028
Elevation (m)
Elevation (m)
1024
0+100
Trap Outlet
13 m @ 3.5%
Horizontal Scale 1:1000
Vertical Scale 1:200
A
Natural Creek
1018
Cell #2
71 m
1016
0+000
1026
-
-
1022
1020
1028
E
D
Elevation (m)
Surveyed
Water Level
(June 2, 2014)
Elevation (m)
A
1018
0+015
Trap Outlet
Scale 1:300
Revision
Westmoreland Coal Company
Sediment Trap 3 (ST3)
As-Built Profile and Sections
in conceptual design)
See site photographs 5 to 8 on Figure 9.
During a flood, the majority of flows will be conveyed by the natural channel and
floodplain with some additional conveyance provided by the sediment trap.
Permit to Practice
P5540
0
July 7, 2014
No.
Date
Date:
Issued Final
Description
Project:
July 2014
5821-OB-SC-14
Technical:
KC
By
Reviewer:
K. Curtis
Drawn:
D. Cooper
Z. Steele
Obed Mountain Mine Apetowun Creek Sediment Control Traps
Figure
7
Sandbags On-Hand
Treated Jute
DX Culvert
Treated Jute
Treated Jute
Treated Jute
Jute Curtains
Jute Curtains
Photo 1: ST1. Looking upstream from Outlet with DX Culvert in background – June 2 2014. Photo courtesy of Millennium EMS
Solutions.
Photo 2: ST1. Looking downstream from Inlet – May 26 2014. Photo courtesy of Millennium EMS Solutions.
Sandbags On-Hand
Sandbags On-Hand
Treated Jute
Treated Jute
Jute Curtains
Jute Curtains
Photo 3: ST2A. Looking downstream from Inlet – May 30 2014. Photo courtesy of Millennium EMS Solutions.
Photo 4: ST2B. Inlet on right, Outlet on left – May 29 2014. Photo courtesy of Millennium EMS Solutions.
Revision
Stamp
Westmoreland Coal Company
Site Photographs
0
July 7, 2014
Issued Final
No.
Date
Description
Date:
July 2014
Project:
5821-OB-SC-14_CJ
Technical:
K. Curtis
Reviewer:
KC
By
D. Cooper
Drawn:
C. White
Obed Mountain Mine Apetowun Creek Sediment Control Traps
Figure
8
Base Flows Maintained in Apetowun Creek
Trap Inlet
Jute Curtains
Cell #1
Sandbags On-Hand
Cell #1
Photo 5: ST3, Cell #1. Looking upstream at Inlet – May 26 2014. Photo courtesy of Millennium EMS Solutions.
Photo 6: ST3, Cell #1. Looking upstream at Inlet – May 14 2014. Photo by Katy Curtis, P.Eng. of Matrix Solution Inc.
Sandbags On-Hand
Jute Curtains
Cell #2
Photo 7: ST3, Cell #2. Looking downstream at Cell #2 with sill between Cells #1 and #2 visible on left – May 26 2014 Photo courtesy
of Millennium EMS Solutions.
Photo 8: ST3, Cell #2. Looking downstream at Outlet from Cell #2 to Apetowun Creek – May 26 2014. Photo courtesy of Millennium
EMS Solutions.
Revision
Stamp
Westmoreland Coal Company
Site Photographs
0
July 7, 2014
Issued Final
No.
Date
Description
Date:
July 2014
Project:
5821-OB-SC-14_CJ
Technical:
K. Curtis
Reviewer:
KC
By
D. Cooper
Drawn:
C. White
Obed Mountain Mine Apetowun Creek Sediment Control Traps
Figure
9
CVRI – Obed Mountain Mine
2014 Sediment Trap Assessment
APPENDIX 2: 2014 WATER QUALITY DATA
March 2015
24 Hour Averaged Turbidity (NTU)
PROJECT:
Obed Mountain Mine
NOTES:
represents the average turbidity measurement of all measurements from 12 hours
previously to 12 hours beyond that point of time.
TITLE:
24 Hour Averaged Turbidity Apetuwon Creek Turbidity Sondes
..14-00001\Sed Trap Assessment\Graphs.dwg
DRAWN:
JG
CHECKED: EG
DATE:
Feb 4/15
PROJECT: 14-00001
FIGURE:
1a
24 Hour Averaged Turbidity (NTU)
PROJECT:
Obed Mountain Mine
NOTES:
represents the average turbidity measurement of all measurements from 12 hours
previously to 12 hours beyond that point of time.
TITLE:
24 Hour Averaged Turbidity Apetuwon Creek Turbidity Sondes
..14-00001\Sed Trap Assessment\Graphs.dwg
DRAWN:
JG
CHECKED: EG
DATE:
Feb 4/15
PROJECT: 14-00001
FIGURE:
1b
CVRI – Obed Mountain Mine
2014 Sediment Trap Assessment
APPENDIX 3: 2014 SEDIMENT TRAP BATHYMETRY DATA
March 2015
Sediment
Trap
ST1
ST2A
ST2B
ST3
Cell
1
1
1
1
2
Survey
Date
29-May-14
1-Jun-14
1-Jun-14
2-Jun-14
2-Jun-14
As Built Survey
July Bathymetry Data
Sediment
Accumulation
Surface Area
Water
Surface Area
Water Volume Adjusted Water
Water
Surveyed Water
Survey Date
2
3
2
3
3
(m3)
Level (m) (m )
Level (m)
Volume (m )
(m )
(m )
Volume (m )
1264.75
879.5
1414.27
29-Jul-14
1264.93
747
1128.0
1007
407
1223.38
984.37
985.23
30-Jul-14
1223.77
1019
1187.0
842.0
143
1222.00
1138.8
1435.81
29-Jul-14
1222.37
1163
1046.0
720.4
715
1024.10
741.45
726.18
29-Jul-14
1024.35
662
548.8
407.1
319
1021.60
774.95
737.24
29-Jul-14
1021.95
651
682
469.6
268
CVRI – Obed Mountain Mine
2014 Sediment Trap Assessment
APPENDIX 4: SEDIMENT TRAP INSPECTION FORM
March 2015
OBED MOUNTAIN MINE
APETOWUN SEDIMENT TRAP 1 (ST1)
INSPECTION FORM
STAFF GAUGE
#1 (m):
WATER LEVELS #2 (m):
If applicable
(mark locations on sketch)
TURBIDITY
#1 (NTU):
in creek, ____m upstream of trap inlet
#2 (NTU):
in trap, near inlet
#3 (NTU):
in trap, near outlet
#4 (NTU):
in creek, ____m downstream of trap outlet
LOCATON
PROBLEMS
YES
NO
If ‘YES’, take photographs, measure, describe below, and mark locations on
sketch provided. If practical, mark problem area in the field using stakes and/or
spray-paint to monitor incremental changes.
Displacement of rock
armouring.
Debris causing blockage.
TRAP
INLET
Piping (presence of fine silt) in
seepage flow, making water
murky.
Floc blocks (if present) are not
fully submerged or covered in
sediment, or dissolved.
Displacement of rock
armouring.
Debris causing blockage.
TRAP
OUTLET
Piping (presence of fine silt) in
seepage flow, making water
murky.
Erosion/scour in creek
downstream of outlet
Settling/ sinkholes/ cavities
ACCESS
ROAD AND
DISTURBED
AREA
ADJACENT
TO TRAP
TRAP
Rutting
Erosion from runoff
Cracks (longitudinal or
transverse)
Bare zones in re-vegetation
area
Curtains (if present) are
dislodged or sagging
Debris floating
Version 1 – April 29, 2014
Page 1 of 2
(TO BE COMPLETED AFTER INSPECTION)
INSPECTOR:
DATE:
TIME:
PRECIPITATION IN THE LAST 24HRS (mm):
WEATHER CONDITIONS:
SUMMARY:
Yes No
Overall stability issues
Fish passage issues
Sediment removal required
NOTES:
• Bring tape measure/ camera/ spray paint/ survey
stakes
• Note anything unusual or anything that has
changed since the last inspection
• Use attached sediment trap sketches to indicate
problem areas
• If floc blocs are present, ensure the blocks are
submerged in water and wipe off accumulated
sediment.
OBED MOUNTAIN MINE
APETOWUN SEDIMENT TRAP 1 (ST1)
LOCATON
PROBLEMS
YES
NO
If ‘YES’, take photographs, measure, describe below, and mark locations on sketch
provided. If practical, mark problem area in the field using stakes and/or spraypaint to monitor incremental changes.
Slope movement (slide/
slough/ bulge)
Cracks
(longitudinal or transverse)
TRAP
SIDESLOPES
Seepage (natural springs)
Erosion from runoff
Bare zones in re-vegetation
area
ST1 Sketch
Sediment Accumulation Notes: (provide estimates of water depth at inlet, middle, and outlet of trap. Note deposition pattern. Provide
recommendations for sediment removal.)
Fish Passage Notes: (ST1, ST2, and ST2B are designed and constructed to maintain fish passage through the trap. ST3 is designed and constructed to
maintain fish passage through the creek and deter fish passage through the trap. However, fish can likely access the trap during high flows.
Note any changes to fish passage, such as formation of ledges >30cm, or water depth <3cm, or isolation of fish in the trap-specifically ST3)
General notes, observations, recommendations:
Version 1 – April 29, 2014
Page 2 of 2
OBED MOUNTAIN MINE
APETOWUN SEDIMENT TRAP 2A (ST2A)
INSPECTION FORM
STAFF GAUGE
#1 (m):
WATER LEVELS #2 (m):
If applicable
(mark locations on sketch)
TURBIDITY
#1 (NTU):
in creek, ____m upstream of trap inlet
#2 (NTU):
in trap, near inlet
#3 (NTU):
in trap, near outlet
#4 (NTU):
in creek, ____m downstream of trap outlet
LOCATON
PROBLEMS
YES
NO
If ‘YES’, take photographs, measure, describe below, and mark locations on
sketch provided. If practical, mark problem area in the field using stakes and/or
spray-paint to monitor incremental changes.
Displacement of rock
armouring.
Debris causing blockage.
TRAP
INLET
Piping (presence of fine silt) in
seepage flow, making water
murky.
Floc blocks (if present) are not
fully submerged or covered in
sediment, or dissolved.
Displacement of rock
armouring.
Debris causing blockage.
TRAP
OUTLET
Piping (presence of fine silt) in
seepage flow, making water
murky.
Erosion/scour in creek
downstream of outlet
Settling/ sinkholes/ cavities
ACCESS
ROAD AND
DISTURBED
AREA
ADJACENT
TO TRAP
TRAP
Rutting
Erosion from runoff
Cracks (longitudinal or
transverse)
Bare zones in re-vegetation
area
Curtains (if present) are
dislodged or sagging
Debris floating
Version 1 – April 29, 2014
Page 1 of 2
(TO BE COMPLETED AFTER INSPECTION)
INSPECTOR:
DATE:
TIME:
PRECIPITATION IN THE LAST 24HRS (mm):
WEATHER CONDITIONS:
SUMMARY:
Yes No
Overall stability issues
Fish passage issues
Sediment removal required
NOTES:
• Bring tape measure/ camera/ spray paint/ survey
stakes
• Note anything unusual or anything that has
changed since the last inspection
• Use attached sediment trap sketches to indicate
problem areas
• If floc blocs are present, ensure the blocks are
submerged in water and wipe off accumulated
sediment.
OBED MOUNTAIN MINE
APETOWUN SEDIMENT TRAP 2A (ST2A)
LOCATON
PROBLEMS
YES
NO
If ‘YES’, take photographs, measure, describe below, and mark locations on sketch
provided. If practical, mark problem area in the field using stakes and/or spraypaint to monitor incremental changes.
Slope movement (slide/
slough/ bulge)
Cracks
(longitudinal or transverse)
TRAP
SIDESLOPES
Seepage (natural springs)
Erosion from runoff
Bare zones in re-vegetation
area
ST2A Sketch
Sediment Accumulation Notes: (provide estimates of water depth at inlet, middle, and outlet of trap. Note deposition pattern. Provide
recommendations for sediment removal.)
Fish Passage Notes: (ST1, ST2, and ST2B are designed and constructed to maintain fish passage through the trap. ST3 is designed and constructed to
maintain fish passage through the creek and deter fish passage through the trap. However, fish can likely access the trap during high flows.
Note any changes to fish passage, such as formation of ledges >30cm, or water depth <3cm, or isolation of fish in the trap-specifically ST3)
General notes, observations, recommendations:
Version 1 – April 29, 2014
Page 2 of 2
OBED MOUNTAIN MINE
APETOWUN SEDIMENT TRAP 2B (ST2B)
INSPECTION FORM
STAFF GAUGE
#1 (m):
WATER LEVELS #2 (m):
If applicable
(mark locations on sketch)
TURBIDITY
#1 (NTU):
in creek, ____m upstream of trap inlet
#2 (NTU):
in trap, near inlet
#3 (NTU):
in trap, near outlet
#4 (NTU):
in creek, ____m downstream of trap outlet
LOCATON
PROBLEMS
YES
NO
If ‘YES’, take photographs, measure, describe below, and mark locations on
sketch provided. If practical, mark problem area in the field using stakes and/or
spray-paint to monitor incremental changes.
Displacement of rock
armouring.
Debris causing blockage.
TRAP
INLET
Piping (presence of fine silt) in
seepage flow, making water
murky.
Floc blocks (if present) are not
fully submerged or covered in
sediment, or dissolved.
Displacement of rock
armouring.
Debris causing blockage.
TRAP
OUTLET
Piping (presence of fine silt) in
seepage flow, making water
murky.
Erosion/scour in creek
downstream of outlet
Settling/ sinkholes/ cavities
ACCESS
ROAD AND
DISTURBED
AREA
ADJACENT
TO TRAP
TRAP
Rutting
Erosion from runoff
Cracks (longitudinal or
transverse)
Bare zones in re-vegetation
area
Curtains (if present) are
dislodged or sagging
Debris floating
Version 1 – April 29, 2014
Page 1 of 2
(TO BE COMPLETED AFTER INSPECTION)
INSPECTOR:
DATE:
TIME:
PRECIPITATION IN THE LAST 24HRS (mm):
WEATHER CONDITIONS:
SUMMARY:
Yes No
Overall stability issues
Fish passage issues
Sediment removal required
NOTES:
• Bring tape measure/ camera/ spray paint/ survey
stakes
• Note anything unusual or anything that has
changed since the last inspection
• Use attached sediment trap sketches to indicate
problem areas
• If floc blocs are present, ensure the blocks are
submerged in water and wipe off accumulated
sediment.
OBED MOUNTAIN MINE
APETOWUN SEDIMENT TRAP 2B (ST2B)
LOCATON
PROBLEMS
YES
NO
If ‘YES’, take photographs, measure, describe below, and mark locations on sketch
provided. If practical, mark problem area in the field using stakes and/or spraypaint to monitor incremental changes.
Slope movement (slide/
slough/ bulge)
Cracks
(longitudinal or transverse)
TRAP
SIDESLOPES
Seepage (natural springs)
Erosion from runoff
Vegetation (bare areas)
ST2B Sketch
Sediment Accumulation Notes: (provide estimates of water depth at inlet, middle, and outlet of trap. Note deposition pattern. Provide
recommendations for sediment removal.)
Fish Passage Notes: (ST1, ST2, and ST2B are designed and constructed to maintain fish passage through the trap. ST3 is designed and constructed to
maintain fish passage through the creek and deter fish passage through the trap. However, fish can likely access the trap during high flows.
Note any changes to fish passage, such as formation of ledges >30cm, or water depth <3cm, or isolation of fish in the trap-specifically ST3)
General notes, observations, recommendations:
Version 1 – April 29, 2014
Page 2 of 2
OBED MOUNTAIN MINE
APETOWUN SEDIMENT TRAP 3 (ST3)
INSPECTION FORM
STAFF GAUGE
#1 (m):
WATER LEVELS #2 (m):
If applicable
(mark locations on sketch)
TURBIDITY
#1 (NTU):
in creek, ____m upstream of trap inlet
#2 (NTU):
in trap, near inlet
#3 (NTU):
in trap, near outlet
#4 (NTU):
in creek, ____m downstream of trap outlet
LOCATON
PROBLEMS
YES
NO
If ‘YES’, take photographs, measure, describe below, and mark locations on
sketch provided. If practical, mark problem area in the field using stakes and/or
spray-paint to monitor incremental changes.
Displacement of rock
armouring.
Debris causing blockage.
TRAP
INLET
Piping (presence of fine silt) in
seepage flow, making water
murky.
Floc blocks (if present) are not
fully submerged or covered in
sediment, or dissolved.
Displacement of rock
armouring.
Debris causing blockage.
TRAP
OUTLET
Piping (presence of fine silt) in
seepage flow, making water
murky.
Erosion/scour in creek
downstream of outlet
SILL FROM
UPPER TO
LOWER CEC
Displacement from rock
armoring
Debris
Settling/ sinkholes/ cavities
ACCESS
ROAD AND
DISTURBED
AREA
ADJACENT
TO TRAP
Rutting
Erosion from runoff
Cracks (longitudinal or
transverse)
Bare zones in re-vegetation
area
Version 1 – April 29, 2014
Page 1 of 2
(TO BE COMPLETED AFTER INSPECTION)
INSPECTOR:
DATE:
TIME:
PRECIPITATION IN THE LAST 24HRS (mm):
WEATHER CONDITIONS:
SUMMARY:
Yes No
Overall stability issues
Fish passage issues
Sediment removal required
NOTES:
• Bring tape measure/ camera/ spray paint/ survey
stakes
• Note anything unusual or anything that has
changed since the last inspection
• Use attached sediment trap sketches to indicate
problem areas
• If floc blocs are present, ensure the blocks are
submerged in water and wipe off accumulated
sediment.
OBED MOUNTAIN MINE
APETOWUN SEDIMENT TRAP 3 (ST3)
LOCATON
PROBLEMS
Curtains (if present) are
dislodged or sagging
TRAP
YES
NO
If ‘YES’, take photographs, measure, describe below, and mark locations on
sketch provided. If practical, mark problem area in the field using stakes
and/or spray-paint to monitor incremental changes.
upper
lower
upper
Debris floating
Slope movement (slide/
slough/ bulge)
Cracks
(longitudinal or transverse)
TRAP
SIDESLOPES
lower
upper
lower
upper
lower
upper
Seepage (natural springs)
lower
upper
Erosion from runoff
Bare zones in re-vegetation
area
lower
upper
lower
ST3 Sketch
Sediment Accumulation Notes: (provide estimates of water depth at inlet, middle, and outlet of trap. Note deposition pattern. Provide
recommendations for sediment removal.)
Fish Passage Notes: (ST1, ST2, and ST2B are designed and constructed to maintain fish passage through the trap. ST3 is designed and constructed to
maintain fish passage through the creek and deter fish passage through the trap. However, fish can likely access the trap during high flows.
Note any changes to fish passage, such as formation of ledges >30cm, or water depth <3cm, or isolation of fish in the trap-specifically ST3)
General notes, observations, recommendations:
Version 1 – April 29, 2014
Page 2 of 2
OBED MOUNTAIN MINE
APETOWUN SEDIMENT TRAPS (ST1, ST2A, ST2B, ST3)
SEDIMENT REMOVAL FORM
SEDIMENT TRAP ID:
INSPECTOR:
DATE:
PROCEDURE
1. Isolate the sediment trap:
All Traps:
Place fish block nets at the inlet and outlet of the trap. Option to use 6” or 8” pump bypass around
trap. Pump bypass does not necessarily need to convey the entire creek flow.
ST3 Option: Use sandbags at the inlet and outlet to completely block flow through the trap and pass all flows
through the natural creek.
2. Perform Fish Rescue in sediment trap: (approx. 1 day)
All Traps:
A Qualified Aquatic Environment Specialists (QAES) will perform a fish salvage in the trap.
3. Remove the sediment:
All Traps:
Use vacuum trucks to remove sediment from the trap. This should not cause elevated turbidity levels
in the trap. The sediment will be hauled to the disposal area which is currently the Red Pit at the
mine. The volume of solids and deposition patterns that are removed will be tracked below.
ST3 Option: If sandbags are used for the isolation (Step 1), then sediment removal can be accomplished with a longstick hoe and haul trucks instead of a vacuum truck. Gradually remove sand bags to restore flow to
minimize temporary elevated turbidity levels in the trap.
4. Remove the isolation and resume trap operation:
All Traps:
Once the sediment removal is completed, remove the fish block nets and pump bypass.
ST3 Option: Allow water in the sediment trap to settle until the turbidity is within acceptable limits, as determined
by the QAES. Then gradually remove the sandbags and allow flow through the sediment trap.
RECORD
Method of Removal
(vacuum/excavator/other)
Describe the sediment
accumulation (location in
trap/approx. depth). Use
sketches on reverse side.
Issues (equipment access,
plugged intake hose, etc.)
Sediment Volume Removed
(m3) and TSS value (to
calculate % water and %
sediment)
Lab particle size analysis
Page 1 of 2
Version 1 – April 29, 2014
OBED MOUNTAIN MINE
APETOWUN SEDIMENT TRAPS (ST1, ST2A, ST2B, ST3)
ST1
ST2A
ST2B
ST3
Page 2 of 2
Version 1 – April 29, 2014
CVRI – Obed Mountain Mine
2014 Sediment Trap Assessment
APPENDIX 5: PHOTOGRAPHS
March 2015
CVRI – Obed Mountain Mine
2014 Sediment Trap Assessment
ST1
Photo 1 -Soil Salvage
Photo 3 – Armouring the trap
Photo 5 – Sediment curtains installed
March 2015
Photo 2 - Excavating the trap
Photo 4 – Laying erosion control mat
Photo 6 – Completed trap
CVRI – Obed Mountain Mine
2014 Sediment Trap Assessment
ST2A
Photo 7 - Clearing
Photo 8 - Rough excavation
Photo 9 – Constructing the access road
Photo 10 – Managing the stockpiles
Photo 10 – Trap filling
March 2015
Photo 11 – Completed trap
CVRI – Obed Mountain Mine
2014 Sediment Trap Assessment
ST2B
Photo 12 – Clearing
Photo 14 – Excavating the trap
Photo 16 – Flow through
March 2015
Photo 13 – Soil salvage
Photo 15 – Nearing completion
Photo 17 – Completed trap
CVRI – Obed Mountain Mine
2014 Sediment Trap Assessment
ST3
Photo 18 – Access road
Photo 19 - Timber clearing
Photo 19 – Soil salvaged
Photo 20 – Excavating the trap
Photo 21 – Upper cell complete
Photo 22 – Lower cell complete
March 2015