obed mountain mine - water release solids recovery...

6111 91 Street

Edmonton, AB T6E 6V6

tel: 780.496.9048

fax: 780.496.9049

Suite 325, 1925 18 Avenue NE

Calgary, AB T2E 7T8

tel: 403.592.6180

fax: 403.283.2647

#106, 10920 84 Avenue

Grande Prairie, AB T8X 6H2

tel: 780.357.5500

fax: 780.357.5501

toll free: 888.722.2563

www.mems.ca

Obed Mountain Mine - Water Release

Solids Recovery Project Sediment Trap Maintenance

A Report on the

Removal of the Silt Curtains in

Sediment Traps ST2A, ST2B and ST3

and

Fish Salvage in Sediment Trap ST3

October 2014

Project Number – 14-00001-01

Coal Valley Resources Inc.

Obed Mine Release

10/30/2014

Page No. Project No. 14-00001-01

File # 14-00001-01

October 31, 2014

Mr. Ross Van Bostelen


Obed Mountain Mine

Dear Ross:

RE: Water Act – Sediment Trap Maintenance

Report on Activities in October

INTRODUCTION

In February 2014, activity approved by the Revised Solids Recovery Plan (MEMS 2013) was

commenced to stabilize damage that occurred to Apetowun Creek during the October 31, 2013 Obed

Mountain Mine (OMM) release event.

As part of the remediation works there were four sediment traps constructed on Apetowun Creek.

The purpose of the traps is to capture elevated levels of suspended solids in the creek flow that was

caused by the damage to the creek and the subsequent remediation work. The performance of the

traps was enhanced by the installation of suspended silt curtains. The silt curtains consisted of jute

material that is treated with an anionic polymer which attracts the suspended solids which binds to

the jute.

There were concerns that leaving the curtains in place during the winter will cause ice damage to the

curtains that could remobilize the captured sediment.

The curtains in Sediment Trap 1 (ST1) were previously removed when the pump around diversion

was in place for the DX Culvert cleanout work. 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 lessons learned at ST1 were applied

to the curtain removals for ST2 and ST3.

ST3 is a partial flow through trap where only a proportion of the total creek flow passes through the

trap. The trap has been constructed with an inlet sill height designed to pass flows in excess of 0.3

m3/sec into the trap. As flows during the winter will be below the inlet height the trap will isolate and


Obed Mine Release

10/30/2014

Project No. 14-00001-01

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.

The silt curtains were removed from ST2A, ST2B and ST3. As mentioned the curtains were previously

removed from ST1. The used curtains were disposed off in the Obed Mine Red Pit backfill. The

curtain floats were stored at the Obed Mine for re-use.

THE WORK

Safety:

The Obed Mine retained the Prime Contractor designation for the project and therefore was

responsible for the safety program that was used during the work. Roger Tanguay (OMM Safety

Officer) prepared the Hazard Assessment and the Emergency Response Plan for the work. The field

supervisor for the project was Mike O’Rourke who handled all of the safety items in the field. Mr.

O’Rourke prepared the daily pre-work safety meetings and ensured all personnel were signed off on

the day’s activities.

The work was completed without any incidents or near misses.

Personnel:

Field Supervisor – Mike O’Rourke (MEMS)

Project Coordination – Kevin Peters (MEMS)

Project Manager – Al Watson (MEMS)

Qualified Aquatic Environment Specialists (QAES) – Scott Holroyd, Angie Bourzetos, Jay

Machney (Pisces)

Labour – two men from Backwoods Contracting

Equipment:

Six inch diesel pump c/w hoses

Three inch gas powered pump c/w hoses

Backpack electrofisher

Zodiac c/w electrofisher

Hand tools.

All of the work was supervised by a QAES who undertook the monitoring of the water quality in

Apetowun throughout the project work. The Fisheries Protection Plan (Pisces 2013) was followed

throughout the work duration.


Obed Mine Release

10/30/2014

Project No. 14-00001-01

ST2A

The initial plan was to install a pump around diversion to isolate the pond. Due to problems in

getting the 6” pump close enough to the pond the decision was made to manually open the diversion

dam and to manually install the cofferdam at the inlet to isolate the trap. The creek flow bypassed the

trap in the original channel. As an additional layer of protection for the creek a silt curtain was

installed at the outlet to minimize turbid water leaving the trap. The sediment curtains were floated

to the bank and pulled up on shore.

Photo 1 – Isolating the trap Photo 2 – Silt curtain at the trap outlet

Photo 3 – Removing the curtains Photo 4 – Curtains removed from ST2A

The diversion dam was reinstalled and the cofferdam was removed and flow through the trap

resumed.

There was a minor non-compliance with the fisheries protection plan during the work. When the

diversion dam was removed the flows through the original channel disturbed deposited sediment in

the channel. The work was suspended for approximately ½ hour until the flows cleared.


Obed Mine Release

10/30/2014

Project No. 14-00001-01

ST2B

For the curtain removal for ST2B the 6” pump was installed for the pump around diversion. A

suitable fish screen for the pump was not available so the pump area was isolated with fish nets. The

sump area was electrofished prior to installing the cofferdam and pump. Two Sculpin were removed

from the pump sump area and were transferred to the creek. A temporary sandbag coffer dam was

installed at the trap outlet.

Photo 5 – Isolated pump area Photo 6 – Electrofishing the isolated area

Photo 7 – Constructing the pump sump Photo 8 – Installing the lower coffer dam

There were no non-compliances with the water quality objectives during the course of the work at

ST2B.


Obed Mine Release

10/30/2014

Project No. 14-00001-01

Photo 9 – Downstream splash pad Photo 10 – Diversion pump

Photo 11 – Pulling the curtains Photo 12 – ST2B without curtains

ST3

A sandbag coffer dam was installed at the inlet to isolate the trap. In order to maintain the trap

isolation over the winter the cofferdam will be 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 6” pump was used to pump the upper

cell to the lower cell which had a silt curtain installed at the outlet. The 3” pump was used to pump a

portion of the water to a vegetated area away from the creek. The 3” discharge was monitored to

ensure that there were no effects on the creek. Once the water level was pumped down the cell was

electrofished with the backpack unit 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. As the boat electrofisher unit had arrived the lower cell was

pumped down sufficiently to allow the boat mounted electrofisher to be used. As it worked out the

volume of water pumped from the lower cell completely filled the upper cell.


Obed Mine Release

10/30/2014

Project No. 14-00001-01

Photo 13 – Cofferdam installed Photo 14 – Pump sump in the upper cell

Photo 15 – Silt curtain at the outlet Photo 16 – Electrofishing the upper cell

Photo 17 – Yes… duct tape! Photo 18 – Fish in the trap


Obed Mine Release

10/30/2014

Project No. 14-00001-01

Photo 19 – Netting the upper cell Photo 20 – Pumping to the upper cell

Photo 21 – Electrofishing the lower cell Photo 22 – Processing the salvaged fish

Photo 23 – Upper cell without curtains Photo 24 – Lower cell without curtains

The work on ST3 was completed without any non-compliance with the fisheries protection plan. Ms.

Paulette Penton (Aquatic Habitat Biologist – ESRD) joined us for the work on ST3. Ms. Penton was

pleased with the results of the work, offered some suggestions on improving the methods used and

assisted with the processing of the salvaged fish.


Obed Mine Release

10/30/2014

Project No. 14-00001-01

Fish Salvage:

The following table provides a summary of the results of the fish salvage completed at ST2B and ST3.

Table 1 – Fish Salvage Results

Species Number

Spoonhead Sculpin 294

Rainbow Trout 39

Brook Trout 2

Mountain Whitefish 18

Burbot 7

Total Fish Salvaged 360

All salvaged fish were processed for species, length and weight and then released into Apetowun

Creek. Of interest is that there were no Sculpin salvaged from the ST3 lower cell. Pisces

Environmental will be producing a report providing details on the fish salvage operations.

Sediment Accumulation:

As the upper cell of ST3 was pumped out to for the fish salvage we were able to do an informal

sediment accumulation assessment. It was noted that the downstream end of the cell had

approximately 20 cm of sediment accumulation. The upper section had an average accumulation of

40 cm. While the cells do not require dredging, at this time, it is an indication that the traps are

performing as designed removing suspended solids from the water flowing through the trap. The

following photos illustrate the sediment accumulation.

Photos 25 and 26 – Sediment accumulation


Obed Mine Release

10/30/2014

Project No. 14-00001-01

Water Quality:

The following table provides a summary of the water quality monitoring that was completed during

the work.

Table B-1. TSS results and construction log for Sediment Trap 2A Jute Curtain Removal, October 21, 2014.

Calculated TSS (mg/L)

Exceed

(Y/N) Construction Log, QC/QA and other comments

Time Control (+5 m)

Compliance

Point 1

(-7 m)

Compliance

Point 2

(-14 m)

Compliance

Point 3

(-21 m)

12:15 31.6 21.72 24.27 27.72 N Started opening the natural channel dam wall.

13:15 23.86 84.95 79.87 64.20 Y Flow routed through natural channel. Initial scouring creating

turbidity.

13:45 26.25 30.83 45.83 44.10 N Turbidity returned to compliance. Jute curtains removed.

14:15 25.69 29.05 26.20 39.22 N Flow rerouted through the sediment trap. Activities complete.

Table B-2. TSS results and construction log for Sediment Trap 2B Jute Curtain Removal, October 22, 2014.


Exceed

(Y/N) Construction Log, QC/QA and other comments

Time Control (+5 m)

Compliance

Point 1

(-7 m)

Compliance

Point 2

(-14 m)

Compliance

Point 3

(-21 m)

9:00 26.66 31.23 26.40 29.20 N Flow pump around started and sandbagging of the sediment trap outlet completed.

10:00 27.72 14.1 40.09 30.62 N Removed jute curtains. Activities complete by 9:30.

Table B-3. TSS results and construction log for Sediment Trap 3 Jute Curtain Removal, October 22, 2014.


Exceed (Y/N)

Construction Log, QC/QA and other comments Time

Control

(+5 m)

Compliance

Point 1 (-7 m)

Compliance

Point 2 (-14 m)

Compliance

Point 3 (-21 m)

14:10 11.75 12.46 9.87 10.12 N Started pumping from the upstream cell into the downstream cell.

15:10 7.53 5.14 6.66 5.39 N

Increase in turbidity within the downstream cell from the pumps

discharge. Improving discharge pad and installing a silt curtain at

the downstream end of the downstream cell No significant changes

in turbidity within the creek.

1700 8.04 12.2 10.63 10.23 N Installed second pump to pump water into a vegetated upland area. Started upstream cell FC&R.

Table B-4. TSS results and construction log for Sediment Trap 3 Jute Curtain Removal, October 23, 2014.


Exceed (Y/N)

Construction Log, QC/QA and other comments Time

Control

(+5 m)

Compliance Point 1

(-2 m)

Compliance Point 2

(-4 m)

Compliance Point 3

(-6 m)

9:15 28.89 25.33 30.27 20.96 N Ice present on water surface. Resumed pumping from the upstream

cell into downstream cell and continued upstream cell FC&R.

10:15 7.89 8.75 10.07 8.80 N Continued pumping and upstream cell FC&R.

11:15 10.63 8.39 8.70 10.38 N

Upstream cell FC&R complete. Pumping from the downstream cell

to the upstream cell. No water entering the creek from the sediment

trap.

15:30 8.75 9.92 9.56 9.31 N Starting the downstream cell FC&R. No water entering the creek.

Summary:

The work was completed with one minor water quality non-compliance with the fisheries protection

plan which was mitigated by suspending operations for a half hour. A total of 360 fish were salvaged

and released in Apetowun Creek. All of the silt curtains were removed, the floats were salvaged for

reuse and the curtains were disposed of in the Red Pit Backfill.


Obed Mine Release

10/30/2014

Project No. 14-00001-01

CLOSURE

We thank you for the opportunity to be of assistance to the Coal Valley Resources Obed Mine.

Should you have any questions, please contact either of the undersigned at (780) 391-2501.

Yours truly,

Millennium EMS Solutions Ltd.

Prepared by:

Al Watson, C.E.T.

Senior Project Manager

obed mountain mine - water release solids recovery...

Documents