Temporary Diversion Method 3 of 3

Temporary Diversion Methods

final paper in a three-part series.

Contingency and Completion

Contingency Planning:

Our NCS design and project team, suppliers and client team work closely together to develop an Emergency Action Plan (EAP). Many of these TDM projects are dynamic in nature and can be influenced by several external natural elements such as spring run off or rain upstream causing significant increased water volume and flow with lots or little notice depending on where the wet weather or event is along the waterway being diverted. With this potential increased runoff from surrounding areas into waterways, plans are made in advance of any imminent runoff and the potential for flow to exceed the designed diversion capacity, the project team of Client representative, suppliers and the NCS projects managers / engineering design team collaborate to determine the backup / redundancy plans and the deployment requirements, all this is then incorporated these into the ERP with safe work practices. Training and clearly defined roll assignments is a critical element in ERP preparedness along with designating project specific individuals who will be on site throughout the construction project with proper training and authority to immediately adjust and react to changing conditions, installing backup equipment / personnel, move equipment or materials with the intent of contributing to additional flow and volume. All of this is included into the site-specific project plan and is clearly laid out in the EAP. Both the project plan and the EAP plan are written out, documented and are supported by detailed site-specific drawings identifying the location of where green tagged equipment is (either planned and backup) and where support materials are stored when required.

Demobilization

To maintain effective operating conditions, temporary diversions must be inspected regularly including the start and end of every day. Flow barriers should be inspected for any excess water in dry areas, diversion channels itself should be inspected for any signs of erosion, and lining repairs or maintenance should be completed if any signs of failure. Until construction is complete, water should not be allowed to flow back into natural stream. The project is not complete until the TDM system is removed and remediation of the surrounding natural area is complete.

Reintroducing Water to stream

The TDM should be removed after redirecting the flow through the natural channel. If using Diversion channel, lining material should be removed, and the channel should then be backfilled and stabilized. Prior to releasing water back into the diverted area consider controlling initial sediment release be washing rock, natural materials (logs and vegetation) and stream bed with a low pressure / light stream of water spray applied to wash sediment into the creek bed, then to prevent further sediment from entering waterway, water can be released under a controlled flow. Kinetic energy barriers, original rock and riprap sized accordingly in the initial diversion plan are used to protect the points of tie-in to the natural channel. Using the initial grid plan and pictures maintained from pre-construction inspection, the creek or river is returned to the original natural state.                 Visit: www.ncsfluidsystems.ca