REV DATE DESCRIPTION DESIGNED DRAWN CHK'D APP'D FIGURE … · 2012-05-10 · Knight Piésold Ltd....
Transcript of REV DATE DESCRIPTION DESIGNED DRAWN CHK'D APP'D FIGURE … · 2012-05-10 · Knight Piésold Ltd....
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CLARY LAKE
PATSY LAKE
LAKE 901
LAKE 493
PROJECT LOCATION
REV
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XREF FILE(S): HYDRO_TRIM; Topo1m_22_C6 IMAGE FILE(S): TROUT
REV DATE DESCRIPTION DRAWNDESIGNED CHK'D APP'D
AVANTI KITSAULT MINE LTD.
KITSAULT PROJECT
LAKE 493 DIVERSION TO LAKE 901
PROJECT LOCATION
VA101-343/9 VA11-00935
0FIGURE 1
0 05JUL'11 ISSUED WITH LETTER AS PP VM SRM
0 m100200 200 400 600 800 1000
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6 144 300 N
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6 144 500 N
476 900
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PIPE INLET
STRUCTURE
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(W.L. 746)
LAKE 493
(W.L. 756)
6 144 100 N
476 800
E
OVERLAND HDPE
PIPELINE ROUTE
CULVERT
CULVERT
EXISTING ACCESS
ROAD, TYP.
PIPE OUTLET
INTO LAKE 901
EXISTING ROAD
CULVERT
0 05JUL'11 ISSUED WITH LETTER AS NSD VM SRM
m1020 20 40 60 80 1000
SCALE A
NOTES:
1. COORDINATE GRID IS UTM NAD83, ZONE 10 m.
2. PLAN BASED ON INFORMATION PROVIDED BY McELHANNEY, DATED DEC., 2009.
3. CONTOUR INTERVAL IS 1 METRES.
4. DIMENSIONS AND ELEVATIONS ARE IN METRES, UNLESS NOTED OTHERWISE.
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REV DATE DESCRIPTION DRAWNDESIGNED CHK'D APP'D
AVANTI KITSAULT MINE LTD.
KITSAULT PROJECT
LAKE 493 DIVERSION TO LAKE 901 OPTIONS
OVERLAND PIPELINE
VA101-343/9 VA11-00935
0FIGURE 2
A1-8 of 13
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6 144 200 N
6 144 300 N
6 144 400 N
6 144 500 N
476 900
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477 000
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477 100
E
477 200
E
477 300
E
477 400
E
477 500
E
477 600
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N
PIPE INLET
STRUCTURE
6 144 100 N
476 800
E
BURIED
PIPELINE
CULVERT,
TYP.
LAKE 901
(W.L. 746)
LAKE 493
(W.L. 756)
EXISTING ACCESS
ROAD, TYP.
PIPE OUTLET
INTO LAKE 901
EXISTING ROAD
CULVERT
0 05JUL'11 ISSUED WITH LETTER AS NSD VM SRM
m1020 20 40 60 80 1000
SCALE A
NOTES:
1. COORDINATE GRID IS UTM NAD83, ZONE 10 m.
2. PLAN BASED ON INFORMATION PROVIDED BY McELHANNEY, DATED DEC., 2009.
3. CONTOUR INTERVAL IS 1 METRES.
4. DIMENSIONS AND ELEVATIONS ARE IN METRES, UNLESS NOTED OTHERWISE.
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REV DATE DESCRIPTION DRAWNDESIGNED CHK'D APP'D
AVANTI KITSAULT MINE LTD.
KITSAULT PROJECT
LAKE 493 DIVERSION TO LAKE 901 OPTIONS
BURIED PIPELINE
VA101-343/9 VA11-00935
0FIGURE 3
A1-9 of 13
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6 144 200 N
6 144 300 N
6 144 400 N
6 144 500 N
476 900
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477 000
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477 100
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477 200
E
477 300
E
477 400
E
477 500
E
477 600
E
N
LWD
TIE-IN EXISTING
STREAM AND POOL
RIFFLE/RUN/POOL
DEFLECTION LOG
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POOL DETAIL
ROCK WEIR
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CLUSTERS
RIFFLE/RUN/POOL
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RUN/RIFFLE/POOL
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RIFFLE/RUN/POOL
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CHANNEL INLET
STRUCTURE
TIE IN EXISTING POOL
FIG
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DEFLECTION LOG
6 144 100 N
476 800
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DEFLECTION LOG
BOULDER
CLUSTERS
FIG
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RIFFLE/RUN/POOL
FIG
2
A
BOULDER CLUSTERS
CONCRETE WEIR
LAKE 901
(W.L. 746)
LAKE 493
(W.L. 756)
BOULDER
CLUSTERS
EXISTING ROAD
CULVERT
OVERLAND HDPE
PIPELINE ROUTE
EXISTING ACCESS
ROAD, TYP.
LAKE 493 OUTLET
STRUCTURE
POOL DETAIL
FIG
2
C
0 05JUL'11 ISSUED WITH LETTER AS NSD VM SRM
m1020 20 40 60 80 1000
SCALE A
NOTES:
1. COORDINATE GRID IS UTM NAD83, ZONE 10 m.
2. PLAN BASED ON INFORMATION PROVIDED BY McELHANNEY, DATED DEC., 2009.
3. CONTOUR INTERVAL IS 1 METRES.
4. DIMENSIONS AND ELEVATIONS ARE IN METRES, UNLESS NOTED OTHERWISE.
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REV DATE DESCRIPTION DRAWNDESIGNED CHK'D APP'D
AVANTI KITSAULT MINE LTD.
KITSAULT PROJECT
LAKE 493 DIVERSION TO LAKE 901 OPTIONS
OPEN CHANNEL
VA101-343/9 VA11-00935
0FIGURE 5
A1-11 of 13
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101-343/13-1 Rev 0 March 30, 2012
APPENDIX A2
FISH HABITAT COMPENSATION OF LAKE 901 OUTLET CHANNEL AND TRIBUTARY 886
(Pages A2-1 to A2-11)
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Suite 1400 - 750 West Pender Street Vancouver, BC Canada V6C 2T8 File No.:VA101-343/9-A.01 Cont. No.:VA11-01068 Tel: 604.685.0543 Fax: 604.685.0147 www.knightpiesold.com
August 10, 2011 Mr. Craig Nelsen President & CEO Avanti Kitsault Mine Ltd 880 - 580 Hornby Street Vancouver, BC V6C 3B6 Dear Craig, Re: Kitsault Mine Project – Fish Habitat Compensation of Lake 901 Outlet Channel and
Tributary 886 Introduction Knight Piésold Ltd. (KPL) was retained by Avanti Kitsault Mine Ltd to outline the potential habitat enhancement opportunities within the Lake 901 outlet channel and Tributary 886. The locations of these channels are shown on Figure 1. This letter continues the discussions previously presented in the KPL letters “Kitsault Mine Project – Diversion Options between Lake 493 and Lake 901” (Knight Piésold, 2011a) and “Habitat Compensation Channel” (Knight Piésold, 2011b). This letter discusses the spawning habitat requirements for rainbow trout and the opportunities for incorporating these features within the Lake 901 outlet channel and Tributary 886. Habitat Enhancement Rainbow trout typically spawn in main river channels and their tributaries, and within the inlet and outlet channels of lakes. The preferred spawning location is within well-aerated gravels free of fine sediments at the head of riffles or at the tails of pools (Hunter, 1991). These locations deliver fresh oxygen and wash away waste products from the redds as water constantly flows through the substrate. The following physical habitat features are required in order to create suitable rainbow trout spawning areas: Ideal substrate size is 12 to 38 mm; however, rainbow trout will tolerate gravel as small as 2.5 mm
and as large as 76 mm. Preferred spawning depths range between 0.15 to 0.61 m. Preferred spawning velocities range between 0.2 to 1.0 m/s. During egg development, water depths and velocities may vary as long as the submergence of redds
is maintained. Other features, which are important for rainbow trout rearing habitat, include: Suitable cover provided from overhanging riparian vegetation, in-stream wood and boulders, and
bank structures (e.g. undercut banks). Deep pools and cobble substrate with interstitial spaces for overwintering habitat. Lake 901 Outlet Channel An existing channel profile, cross sections and photographs of the Lake 901 outlet channel are shown on Figure 2 and 3 as provided by Brad Horne of AMEC Earth and Environment Ltd (AMEC). The outlet channel is approximately 318 m long from the outlet of Lake 901 to the culvert crossing located at the existing road downstream. The average channel slope is 3% with predominant step-pool morphology.
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The photographs show that habitat complexity is already present within the stream with riparian vegetation, small riffles and large woody debris (LWD) distributed throughout the system. The proposed habitat enhancement of the Lake 901 outlet channel outlined below aims to complement the existing habitat in the channel and is focused on providing additional spawning and rearing habitat for young-of-the-year (YOY) rainbow trout. The upper section of the Lake 901 outlet channel is too narrow and confined by bedrock to allow for channel alignment manipulation (an example of a bedrock outcrop is shown on Photo 4, Figure 2). Therefore, in order to provide spawning habitat through this reach, rock riffles with spawning platforms will be introduced. Rock riffles with “V” shaped crests act as small in-stream weirs that promote backwatering upstream of the riffle and a section of faster velocities over the elongated rock weir, therefore creating a pool-riffle-run sequence. The pools created upstream of the rock riffles provide deeper, slower moving water suitable for rearing habitat. Localized excavation may be incorporated to create pools with suitable depths for YOY overwintering habitat. The extended tail of the rock riffle creates a run section providing faster velocities, and when stocked with appropriately sized gravels, creates a spawning platform. The proposed placement and details for the rock riffles with spawning platforms are shown on Figure 4 and Figure 5 respectively. Typically, these structures are placed approximately 6 to 7 channel widths apart; however, it is recommended for this system that the rock riffles are placed in a manner that compliments the existing topography and habitat already present within the outlet channel (approximately 3.5 channel widths on average). Through the lower reach of the Lake 901 outlet channel there is more flexibility to incorporate spawning and rearing habitat features. Where possible, rock riffles with spawning platforms, in-stream and off-stream alcove ponds, LWD, boulder clusters and deflector logs will be incorporated. These features will be used to provide spawning habitat, low velocity zones and areas of refuge and cover. Figure 4 shows the potential locations of these features, while Figure 5 shows typical details. Any existing or created pools with a depth greater than 2 m will have LWD incorporated and a double layer of cobble substrate to provide interstitial spaces for overwintering rainbow trout. Depending on the sediment transport potential of the stream, possibility exists for spawning gravels to migrate downstream. To minimize this effect, gravel-retaining structures (e.g. log deflectors, or boulder clusters) will be placed along the channel that will promote sediment accumulation. Additional spawning gravel will also be stockpiled in the upper reaches of the outlet channel, as well as downstream of the bedrock section, as shown on Figure 4. These stockpiles will be placed along the stream banks and will keep contributing new gravel at higher flow events (e.g. 2-10 year flood events), providing for a self-maintained system. They will also serve as reserves for additional spawning sediments when more replenishment is required after floods with even higher return periods. The confluence of Lake 493 and Lake 901 outlet channels is located a small distance downstream of a hanging culvert crossing that is currently impassable for fish to move back upstream. By replacing the culvert with a single span bridge and improving the access, Lake 493 and Lake 901 will be reconnected, therefore providing access to Lake 901 for the fish from Lake 493. The culvert replacement will increase the stream length available to rainbow trout and therefore increase the amount of available habitat. Flows expected in the Lake 901 outlet channel prior to, during the construction and operation phases, and post-operations of the Kitsault Mine Project were estimated in KPL letter “Kitsault Mine Project – Surface Water Hydrology Flow Changes” (Knight Piésold, 2011c). The monthly mean annual hydrographs for the Lake 901 outlet channel are summarized in Table 1 and shown on Figure 6. The outflows of Lake 901
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are estimated assuming that Lake 901 inflow losses are mitigated by diverting flows from the neighboring Lake 493. Tributary 886 Tributary 886 is an inlet channel to Lake 901 as shown on Figure 1. It was considered for spawning habitat enhancement opportunities since the Kitsault Mine Project will not affect its drainage area. Investigation of Tributary 886 revealed that the lower section of the stream is a small, very low gradient channel that does not appear to receive sufficient flows or velocities to provide adequate spawning habitat. The lowermost section of the tributary is influenced by lake fluctuations, followed by a small narrow channel and then a wider channel flowing through a “bog” type plateau (personal comm. with Brad Horne, AMEC). The combined length of these sections is about 150 m. The upstream sections of this tributary incised in a V-shaped bedrock channel may be impassable for fish and offer very limited options for habitat improvement. To increase the flows within Tributary 886, diversion options from Lake 493 were explored; however, these options where deemed unfeasible primarily due to inadequate elevation differences and inability to divert water without pumping. The low gradient of Tributary 886 makes it unsuitable for creating spawning platforms, while the low flows do not provide adequate depths for creating rearing habitat. Habitat enhancement within Tributary 886 is not considered viable at this time; however, additional fieldwork is necessary to fully investigate this option. Recommendations Before a detailed design of the habitat enhancement of the Lake 901 outlet channel is undertaken, the following recommendations are made regarding detailed site investigation and field data collection: Perform detailed topographic survey (0.5 m contours) to enable optimizing the design of the channel
enhancement options. Collect at least one year of continuous stage record at the outlet of Lake 901 (station installed in May
2011), as well as 10 unique stage-discharge measurements in order to develop a rating curve and determine the in-situ outflows for the lake.
Perform site investigations during the rainbow trout spawning season in late May to mid-June to establish the current utilization of the Lake 901 inlet and outlet channels. Collect information on substrate size, water depth and water velocity in those areas that have the highest utilization by spawners.
Undertake additional design and modelling work to confirm that the habitat enhancement works will meet the velocity and depth requirements for spawning rainbow trout.
References Hunter, C. J. Better Trout Habitat: A guide to stream restoration and management. Washington: Island
Press, 1991. Knight Piésold (2011a). Kitsault Mine Project – Diversion Options between Lake 493 and Lake 901. Ref
no.VA11-00935, July 2011. Knight Piésold (2011b). Fish Habitat Compensation Channel. Ref no. VA11-00966. July 2011. Knight Piésold (2011c). Kitsault Mine Project – Surface Water Hydrology Flow Changes. Ref no.VA11-
00964, July 2011.
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XREF FILE(S): HYDRO_TRIM; Topo1m_22_C6 IMAGE FILE(S): TROUT
REV DATE DESCRIPTION DRAWNDESIGNED CHK'D APP'D
AVANTI KITSAULT MINE LTD.
KITSAULT PROJECT
LAKE 901 OUTLET CHANNEL AND TRIBUTARY 886
PROJECT LOCATION
VA101-343/9 VA11-01068
0FIGURE 1
0 08JUL'11 ISSUED WITH LETTER AS NSD VM SRM
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SCALE A
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LAKE 493
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PHOTO #6
LAKE 901 OUTLET LOOKING U/S
PHOTO #5
SECTION 5 LOOKING U/S
PHOTO #3
SECTION 3 LOOKING U/S
PHOTO #1
SECTION 1 LOOKING D/S
PHOTO #7
CULVERT LOOKING U/S
PHOTO #2
SECTION 2 LOOKING U/S
PHOTO #4
SECTION 4 LOOKING U/S
0 08JUL'11 ISSUED WITH LETTER AS NSD VM SRM
15 25 50 75 m7.5 0
SCALE A
NOTES:
1. COORDINATE GRID IS UTM NAD83, ZONE 10 m.
2. PLAN BASED ON INFORMATION PROVIDED BY McELHANNEY, DATED DEC., 2009.
3. CONTOUR INTERVAL IS 1 METRES.
4. DIMENSIONS AND ELEVATIONS ARE IN METRES, UNLESS NOTED OTHERWISE.
5. PHOTOGRAPHS #1-6 PROVIDED BY BRAD HORNE, AMEC EARTH AND
ENVIRONMENTAL INC.
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REV DATE DESCRIPTION DRAWNDESIGNED CHK'D APP'D
AVANTI KITSAULT MINE LTD.
KITSAULT PROJECT
LAKE 901 OUTLET CHANNEL
PLAN
VA101-343/9 VA11-01068
0FIGURE 2
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APPROX. CREEK INVERT
PROFILE ALONG LAKE 901 OUTLET CHANNEL
LAKE 901 OUTLET CHANNEL
SCALE A
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STATION (m)
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STATION (m)
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FIG
SECTION1
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SCALE B
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SCALE B
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0 08JUL'11 ISSUED WITH LETTER AS NSD VM SRM
m0510 10 20 30 40 50
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NOTES:
1. PROFILE BASED ON INFORMATION PROVIDED BY McELHANNEY,
DATED DEC., 2009.
2. DIMENSIONS AND ELEVATIONS ARE IN METRES, UNLESS NOTED
OTHERWISE.
3. SECTION GEOMETRY WAS SURVEYED IN JULY 2010 AND PROVIDED
BY BRAD HORNE, AMEC EARTH AND ENVIRONMENTAL INC.
4. SECTION ELEVATIONS ARE APPROXIMATE.
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REV DATE DESCRIPTION DRAWNDESIGNED CHK'D APP'D
AVANTI KITSAULT MINE LTD.
KITSAULT PROJECT
LAKE 901 OUTLET CHANNEL
PROFILE AND SECTIONS
VA101-343/9 VA11-01068
0FIGURE 3
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SCALE B
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LAKE 901
LAKE 493
ROCK RIFFLE /
SPAWNING PLATFORM
DEFLECTION LOG
FIG
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CLUSTERS
FIG
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DEFLECTION LOG
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ROCK RIFFLE /
SPAWNING PLATFORM
FIG
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ROCK RIFFLE /
SPAWNING PLATFORM
FIG
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ROCK RIFFLE /
SPAWNING PLATFORM
FIG
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ROCK RIFFLE /
SPAWNING PLATFORM
FIG
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ROCK RIFFLE /
SPAWNING PLATFORM
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A
ROCK RIFFLE /
SPAWNING PLATFORM
FIG
5
A
BOULDER
CLUSTERS
FIG
5
C
BOULDER
CLUSTERS
FIG
5
C
BOULDER
CLUSTERS
FIG
5
C
DEFLECTION LOG
FIG
5
D
DEFLECTION LOG
FIG
5
D
LWD / BOULDER
COMPLEX
FIG
5
B
OFF CHANNEL ALCOVE POND
FIG
5
E
OFF CHANNEL ALCOVE POND
FIG
5
E
0 08JUL'11 ISSUED WITH LETTER AS NSD VM SRM
15 25 50 75 m7.5 0
SCALE A
NOTES:
1. COORDINATE GRID IS UTM NAD83, ZONE 10 m.
2. PLAN BASED ON INFORMATION PROVIDED BY McELHANNEY, DATED DEC., 2009.
3. CONTOUR INTERVAL IS 1 METRES.
4. DIMENSIONS AND ELEVATIONS ARE IN METRES, UNLESS NOTED OTHERWISE.
REV
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REV DATE DESCRIPTION DRAWNDESIGNED CHK'D APP'D
AVANTI KITSAULT MINE LTD.
KITSAULT PROJECT
LAKE 901 OUTLET CHANNEL
HABITAT ENHANCEMENT PLAN
VA101-343/9 VA11-01068
0FIGURE 4
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FLOW
FLOW
LOG(S)
PINS
BACKWATER AREA
(VELOCITY REFUGE) COBBLES OR BOULDERS
FOR GRAVEL RETENTION
ANCHOR BOULDERS
ANCHOR PINS AND
CABLES (REBAR)
FLOW
FLOW
GRAVEL
DEPOSITION
BASE EMBEDDED
IN BANK
ARMOUR OPPOSING
BANK BOULDERS)
4
-
4
-
FIG
TYPICAL DETAILA
4
ROCK RIFFLE / SPAWNING PLATFORM
NTS
FIG
TYPICAL DETAILD
4
DEFLECTION LOG
NTS
FIG
TYPICAL SECTION4
-
DEFLECTION LOG
NTS
FIG
TYPICAL SECTION2
-
LWD/BOULDER COMPLEX
NTS
BOULDER
CLUSTER
3
-
3
-
FLOW
BACKWATER AREA
(VELOCITY REFUGE)
BOULDERS
FIG
TYPICAL SECTION3
-
BOULDER CLUSTERS
NTS
FIG
TYPICAL DETAILC
4
BOULDER CLUSTERS
NTS
FLOW
FLOW
BACKWATER AREA
(VELOCITY REFUGE)
BACKWATER AREA
(VELOCITY REFUGE)
2
-
2
-
FIG
TYPICAL DETAILB
4
LWD/BOULDER COMPLEX
NTS
FLO
W
COBBLES
LWD PLACEMENT DESIGNED TO COVER 20%
OF POOL SURFACE AREA
BOULDERS FOR ANCHORING LWD
COBBLES
F
L
O
W
WEIR BOULDER GROUP
COBBLES
COBBLES AND
GRAVEL
SP
AW
NIN
G G
RA
VE
L L
AY
ER
SPAWNING
GRAVEL
COBBLES
FLOW
FLOW
MIX GRAVEL
BOULDERS ALONG PERIMETER
OF SPAWNING GRAVELS
WEIR BOULDER GROUP
(KEYED IN APPROPRIATELY)
1
-
1
-
LWL
FIG
TYPICAL SECTION5
-
OFF CHANNEL ALCOVE POND
NTS
5
-
5
-
FIG
TYPICAL DETAILE
4
OFF CHANNEL ALCOVE POND
NTS
LWD PLACEMENT DESIGNED TO COVER 20%
OF POOL SURFACE AREA
BOULDERS FOR ANCHORING LWD
COBBLES
MAIN
CHANNEL
MAIN
CHANNEL
FIG
TYPICAL SECTION1
-
ROCK RIFFLE / SPAWNING PLATFORM
NTS
6
-
6
-
FIG
TYPICAL CROSS-SECTION6
-
RIFFLE CREST
NTS
"V" SHAPED CREST
1
2
1
2
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REV DATE DESCRIPTION DRAWNDESIGNED CHK'D APP'D
AVANTI KITSAULT MINE LTD
KITSAULT PROJECT
LAKE 901 OUTLET CHANNEL
HABITAT ENHANCEMENT DETAILS
VA101-343/9 VA11-01068
0FIGURE 5
NOTES:
1. LWD (LARGE WOODY DEBRIS) SHOULD RETAIN ROOTWADS AND LIMBS IF
POSSIBLE.
2. CABLING OF LWD MAY NOT BE REQUIRED IF THE STEMS CAN BE PINNED UNDER
BOULDER COMPLEXES.
3. ALL ON-SITE SWD (SMALL WOODY DEBRIS) IS TO BE INCORPORATED INTO THE
POOL OR CHANNEL MARGINS WHERE APPLICABLE. OVERSIZED OR UNDERSIZED
BOULDERS MAY ALSO BE INCORPORATED INTO THE CHANNEL DESIGN.
0 08JUL'11 ISSUED WITH LETTER AS NSD VM SRM A2-10 of 11
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M:\1\01\00343\09\A\Data\Task 600 (Kitsault River Fish Comp)\Lake 901 Outlet Channel Habitat Enhancement\[Outlet Channel Flows.xls]901 Out hydrograph Print 10/08/2011 10:55 AM
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
January February March April May June July August September October November December
Dis
char
ge (m
3 /s)
Month
Baseline and Construction Phase 1 & 2
Construction Phase 3
Operations
Closure and Post-closure
NOTES:1. OUTFLOW VALUES FOR EACH PHASE OF THE MINE LIFE WERE BASED ON THE KP WATERSHED MODEL.2. OUTFLOWS ARE ESTIMATED ASSUMING THAT LAKE 901 INFLOW LOSSES ARE MITIGATED BY DIVERTING
FLOWS FROM NEIGHBOURING LAKE 493.
0 08JUL'11 ISSUED WITH LETTER AS VM SRMDATE DESCRIPTION PREP'D CHK'D APP'DREV
LAKE 901 OUTLET CHANNELMONTHLY HYDROGRAPH
FIGURE 6
AVANTI KITSAULT MINE LTD.
KITSAULT PROJECT
REV0
P/A NO. VA101-343/09
REF. NO.VA11-01068
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101-343/13-1 Rev 0 March 30, 2012
APPENDIX A3
KITSUALT MINE PROJECT – KITSAULT RIVER SIDE CHANNELS
(Pages A3-1 to A3-11)
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Suite 1400 - 750 West Pender Street Vancouver, BC Canada V6C 2T8 File No.:VA101-343/9-A.01 Cont. No.:VA11-00936 Tel: 604.685.0543 Fax: 604.685.0147 www.knightpiesold.com
July 5, 2011 Mr. Craig Nelsen President & CEO Avanti Kitsault Mine Ltd 880 - 580 Hornby Street Vancouver, BC V6C 3B6 Dear Craig, Re: Kitsault Mine Project – Kitsault River Side Channels Knight Piésold Ltd. (KPL) was tasked to further investigate the development of side channel options recommended by LGL Limited in 2007 (LGL, 2007). This letter presents the summary of considerations for fish compensation options for the Kitsault Mine on the Kitsault River. It discusses side channel enhancement opportunities for wild chum salmon stocks on the Kitsault River. Introduction Fisheries inventory data and chum salmon escapement trends illustrate that fall chum salmon stocks in the streams of Statistical Area 3 (including the Kitsault River) have remained depressed for many years. Marc Gaboury and Robert Bocking of LGL Limited undertook a preliminary site investigation on the Lower Kitsault River during the chum salmon spawning season of August 2006. To improve productivity, they proposed habitat enhancement and restoration of side channels to advance stable spawning habitat on the Kitsault River. In their report (LGL, 2007), they identified four possible locations for side channel improvement (Figure 1). Two of the proposed side channels, Channels 1 and 4, are located on the right river bank and are accessible by an existing road. Channels 2 and 3 are located on the left river bank and have no road access. A recent site reconnaissance visit (June 13-14, 2011) was undertaken by Marc Gaboury (LGL Limited), Brad Horne (AMEC), Shawn Ducharme (Nisga’ Fisheries), Craig Nistor (KPL), Sam Mottram (KPL) and Violeta Martin (KPL). The flow conditions on the Kitasult River were reasonably low with the spring freshet conditions already passed. Channels 2 and 3 were investigated from the air, while Channels 1 and 4 were investigated on foot. Channels 1, 2 and 3 were flowing at the time of the visit, while Channel 4 was dry, and based on vegetation it appeared that flows through this channel are infrequent and may have not occurred in several years. It was concluded that side channel restoration is viable for Channels 1 and 4, and not for Channels 2 and 3 due to the lack of road access (Figure 2). Road access to the side channels is necessary both during the construction phase and later for periodic inspections and maintenance. Side Channel Enhancement Proposed side channels 1 and 4 have potential to provide habitat diversity to accommodate the requirements of several fish species and life stages (Figures 3 and 4). The primary focus of restoration works at these two locations is spawning habitat improvement for chum salmon. However, it is also possible to incorporate restoration works on existing ponds and improve rearing and overwintering habitat for juvenile coho salmon as well. Based on the observations during the site reconnaissance visit in June 2011, it appeared that the flows and velocities in Channel 1 might be too low (Photos 1 and 2), while
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flows were non-existent in Channel 4 (Photo 3). Flows in these channels can be increased by excavating deeper channels and promoting additional ground water inflow, while chum salmon spawning habitat can be improved by placing adequate gravel substrate. The existing rearing habitat for juvenile coho salmon (Photo 4) can be enhanced by providing good connectivity to side channels 1 and 4, culvert replacement where necessary and placement of large woody debris (LWD) for cover. The Lower Kitsault River is geomorphologically very active with braided sections and gravel bars shifting the thalweg position on an annual basis. For this reason, surface intake structures are not recommended. The bedload and suspended sediment load in the river are very high, and maintenance and operation of surface intakes and side channels fed by these intakes would require ongoing attention. Surface intake structures must be inspected and maintained regularly to remove accumulated debris (Slaney and Zaldokas, 1997). The ongoing maintenance is a challenging task in remote areas if stewardship groups or local contractors cannot be employed. This appears to be the case for the Lower Kitsault River, primarily due to the remoteness of this area and lack of connection by land transportation routes. Side channels located on the river floodplain, fed by groundwater and protected by berms from the river mainstem represent a much more practical option for the Lower Kitsault River. To ensure adequate flows in a groundwater fed channel, the invert of these channels needs to be excavated below the elevation of the river mainstem (typically 0.9 to 1.2 m below the lowest water table in the summer and approximately 1.5 m below the bed of the main river channel). Low longitudinal berms are constructed from the excavated material, which run parallel to the side channel, between the side channel and the river mainstem. The top berms that are located at the upstream end of side channels and run along the river mainstem have the highest exposure to direct flooding by the Kitsault River. The top berms are recommended to be protected by riprap and constructed to a higher elevation than the longitudinal berms. The top berms should be constructed of well graded material to prevent scour or clogging by fines, with construction materials sized to promote the passage of inflows from the river into the side channels through the berms. The side channel protection berms are designed for overtopping by moderate flood events (e.g. a flood with a 30 year return period or higher). This safe-fail philosophy for berm design is an approach that reduces floodplain impacts and flood protection costs, while minimizing the impacts on the river regime (Slaney and Zaldokas, 1997). Minor maintenance and repairs are usually required only after major flood events. The total channel lengths considered for restoration works are 1200 m and 750 m for side channel 1 and 4, respectively. The cross-section of a groundwater fed channel is typically trapezoidal with bank slopes of 1.5 horizontal to 1 vertical. The bottom width (typically 2 m to 5 m) and low channel slope (up to 1%) are selected such that a water depth of 0.25 m to 0.5 m (up to about 1 m) is achieved. In areas where spawning is expected, the banks should be protected by 0.2 m to 0.5 m sized riprap to prevent bank erosion. The gravel substrate for spawning should contain grain sizes between 1 and 10 cm with less than 10% fines (< 6 mm diameter). The area of spawning gravel patches should be at least 2.5 m2 in size. Existing off-channel ponds can be excavated deeper as necessary and connected to side channels to provide rearing and overwintering habitat for juveniles.
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Attachments: Figure 1 Rev 0 Map 1 – Lower Kitsault River (from LGL 2007 report) Figure 2 Rev 0 Kitsault River – Channel Morphology Overview Figure 3 Rev 0 Kitsault River – Side Channel 1 Figure 4 Rev 0 Kitsault River – Side Channel 4 Figure 5 Rev 0 Side Channel and Berm Details Photo 1 Existing Side Channel 1 – upstream section Photo 2 Existing Side Channel 1 – middle section Photo 3 Side Channel 4 - not active Photo 4 Existing pond near Side Channel 4 for coho salmon rearing habitat Copy To: Shane Uren (Greenwood Environmental Inc.) and Brad Horne (AMEC Earth &
Environmental Limited) /vm
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