Soo River Hydro Intake Sediment Management

Transcription

1 Intake Sediment Management GENERATE 2014 Operators Workshop 15 October 2014 by Stuart Croft Vice President

2 A brief background Soo River Project: 14 MW run-of-river development 15 km north of Whistler on the Soo River Develops m of head; design flow of 15 m 3 /s Consists of a inflatable diversion weir and intake, 960 m long tunnel, 240 m long 2 m DIA buried penstock, 2 x 7 MW Francis units, powerhouse, and tailrace Commissioned in May 1994

3 Diversion & Intake Design Setting Diversion situated on a low gradient reach of a coastal river draining 250 km 2 glaciated basin High flow period: May thru October Bedload predominantly silt and sand, some pebbles Floating and submerged woody debris is common Soo River Hydro headworks, Autumn 2012 (photo: Brian Rode)

4 Diversion & Intake Design

5 Diversion & Intake Design

6 Sediment Removal Challenge How to remove ~ 3,000 m 3 /yr silt during fisheries window with minimal disruption to operations & environment? Annual build-up of silt High Flow (and High sand clogging intake, Production) period eroding runners Fisheries Window 15 July to 15 September 15 April to 15 October Autumn storm events

7 Dewater & Excavate? Process Complete plant shutdown Lower headpond Fish recovery Excavate & haul away Soo River Hydro headpond excavation, 2006 Problems Loss of high value production Difficult to dewater fully Handling & disposal of saturated materials Operating equipment on saturated sediments

8 Dredging? Process Systematically suction silt and sand from the intake channel Discharge to impoundment pond, Allow sediments to settle overnight Water exfiltrates through base of pond, or Clarified water is decanted by pumping from surface of pond Over flow is filtered, returned to River Sand pile is allowed to dry, then loaded and trucked from site Excerpt from Cascade Environmental Resources Group Ltd., Environmental Monitoring Report for 2013 Soo River Intake Sediment Removal Considerations Turbidity from excavation is contained Minimal site impact, footprint, equipment requirements Generation operations are not affected

9 Dredging Equipment & Layout Construct settling pond / decant works Assemble purpose-built floating dredge platform, including Toyo DL H.P., 10 electric slurry pump with agitator and cutter head Pump hoisting winch Electric capstan to move platform along cable anchored to shore 6 discharge line On-board electric panel Dredge area systematically removing silt and sand from the intake channel Approximate dredging flow ~ 600 US gpm with a maximum of 20% solids.

10 Dredging Equipment & Layout 4 slurry line from DT-20 discharging to settling basin Floating top draw arrangement for pump to sand filter; note sediment wedge accumulated in opposite corner

11 Dredging Equipment & Layout Sand filters treating decant water drawn from top of water column at settling basin (at left), with discharge back to Soo River mainstem (to right) Dredge in action

12 Final Thoughts Intake sediment removal has become part of Soo River Hydro annual operations Innovative, small-scale dredging has allowed Soo River Hydro to address a serious maintenance issue with relatively little impact on vital late summer energy deliveries FOR MORE INFO... Please contact Stuart Croft Summit Power stu.croft@summitpower.ca or Nels Powell SOR Site Operations Manager nels.jensentech@gmail.com