Steep Slope Rock Swale Construction to Control Debris Flows
Teck Greenhills Swale Remediation
Location:
Teck Greenhills Coal Mine, Elkford, BC
Client:
Teck Metals
Objective:
To construct an armoured swale in an existing eroded steep gully subject to coal slurry debris flows.
Background:
An existing steep gulley was located near the coal breaker at the Greenhills Mine. Since the coal breaker is located on a side hill there is limited working room around the breaker. During times of heavy rainfall or snowmelt mud and coal slurry would build up on the roadways and working area around the breaker. This material would normally be piled for removal but at times was either allowed to flow down the gulley or was pushed down the gulley effectively acting as a debris flow and resulting in erosion and debris build up.
In spring 2010 Terra Erosion Control Ltd. (TEC) partnered with Apex Geoscience Ltd. (Apex) was commissioned by Teck Metals to review the site and provide a solution.
Eroded Gulley, Spring 2010, prior to treatment
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Eroded Gulley and Breaker, Spring 2010,
prior to treatment
Roadway Above Gulley, Spring 2010,
prior to treatment
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Rock Swale Construction:
The design objective for the eroded gulley was to both control mud and slurry input to the swale and provide adequate erosion protection in the event emergency or accidental mud and slurry discharge to the swale. The primary intent of the swale is to only handle storm and snowmelt runoff. Under normal operating conditions slurry and mud are intended to be loaded and trucked away from the coal breaker area.
The implemented project consists of the following:
- Excavation of a round bottom swale approximately 103 m long, 7.0 to 18.6 m wide by at least 2.0 m deep.
- Placement of a geotextile filter in swale.
- Placement of D50~600mm (600mm average rock size by mass), rock in the swale 0.9 m deep in 2:1 sections and 1.2 m deep in 1.5:1 sections.
- Construction of a rock run out ditch at the bottom of the swale.
- Construction of a rock roadway ditch inlet at the bottom of the swale.
- Construction of a concrete block inlet control and equipment safety barrier at the top of the swale.
Due to the steep slope, the majority of the excavation and rock placement work was done with a Kaiser S2 spyder hoe provided by Nu Creek Developments Ltd. A Teck Metals contractor was used to remove excavated material from the top and bottom of the swale and to supply rock to the top and bottom of the swale.
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Start of Swale Excavation, Fall 2010
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Swale Excavation Nearly Complete, Fall 2010
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Placement of Geotextile, Fall 2010
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Placement of Geotextile, Fall 2010
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Placement of Rock, Fall 2010
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Placement of Rock, Fall 2010
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Placement of Concrete Block
Inlet Control Structure, Fall 2010
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Completed Concrete Block
Inlet Control Structure, Fall 2010
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Completed Swale, Fall 2010
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Completed Swale, Fall 2010
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Completed Swale, Fall 2010
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Completed Swale, Fall 2010
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In Service Swale, Summer 2011
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In Service Swale, Summer 2011
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In Service Swale, Summer 2011
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As-Built Plan View of Rock Swale
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As-Built Plan Detail of Concrete Block Inlet Control Structure
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As-Built Typical Rock Swale Section
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As-Built Profile Detail of Concrete Block Inlet Control Structure
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As-Built Section Detail of Concrete Block Inlet Control Structure
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Copyright © 2010
Terra Erosion Control Ltd.
Steep Slope Rock Swale Construction to Control Debris Flows
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