Fish Habitat and Flood Protection Improvements for the Hatzic Lake/Dewdney Area

Year 2009
Proponent Dewdney Area Improvement District
Project type Habitat
FSWP funding source DFO Fraser Basin Initiative
Grant amount $40,000
Total project value $124,000
ID number 09-D7-H

Location: Fraser Valley

Project Summary

Overview

The existing pump station is believed to cause significant juvenile fish mortalities (Associated Engineering 1992, Thomson 1999, Golder 2003). In addition, adult salmon migration to the lake in the summer is impeded by the Dewdney Dike. Frequent flooding within the Hatzic / Dewdney area occurs as a result of the inadequate pump capacity and significant sediment loading within the lake.

This project will undertake the following preliminary engineering design studies:
¥ Fish Access Improvements at Dewdney Dike - This would include designing a new “fish friendly” pump station which will reduce the fish mortality caused by the existing pump station. A preliminary design of a fishway through the Dewdney dike to improve adult salmon access to the lake would be completed.
¥ Flood Risk Reduction - Increase the pump station capacity to reduce flood frequency and severity.  This can be achieved by design of a new primary pump station.  The existing station would be used only as a supplementary pump. (Figures 1 and 2)
¥ Fish Access to Hatzic Slough Đ A scoping study will be conducted to assess the impact of heavy sedimentation at the north end of the lake on fish access to Hatzic and Chilqua Sloughs (Figure 3).


Objectives
1. To address the long standing issue of fish mortality caused by the antiquated pump station at Hatzic Lake by designing a new “fish friendly” primary pump facility.
2. To improve fish access to Hatzic Lake in the summer by incorporating a fishway into the design of a new pump station.
3. To assess the potential impact of heavy sedimentation at the north end of the lake on fish access to Hatzic and Chilqua Sloughs in a scoping study.


Methods

DAID will be the Project Managers for this project. Golder Associates Ltd (Golder) will be the subcontractors to DAID and assemble the project team to carry out the engineering design.  Golder will engage Associated Engineering Ltd. to assist with structural, mechanical and electrical design. 

The proposed methodology to address each of the above objectives is summarized below:

New Primary Pump Station - A review of past pump station design studies for Hatzic Lake and the FVRWC Hammersley Pump study will be conducted to finalize the pump design. A detailed land survey will be completed of the proposed pump station location.  A geotechnical investigation of the ground conditions at the site will be undertaken to provide input into the foundation design.  A multi-disciplinary engineering design team (hydrotechnical, geotechnical, electrical, mechanical and structural) will produce preliminary design drawings and a construction cost estimate for the pump station. Minimizing fish mortality will be one of the primary design criteria.

Fishway - Proposed fishway design options developed for the Dewdney Dike will be reviewed, (including retro-fitting a suitable fishway design into the existing flood box through Dewdney Dike).  Based on the review, design recommendations and options will be discussed with regulatory authorities, stakeholders and the engineering team to produce preliminary design drawings and a cost estimate. 

Fish Access to Hatzic Slough Đ A scoping study on the potential impact of sedimentation in the north end of the lake on fish access to Hatzic and Chilqua Sloughs will be conducted.  This will consist of determining the cross-sectional areas of the channel and water flows during the summer and fall period and assessing if channel improvements are required to improve fish passage. A preliminary sediment management program will be developed to address fish access and flood risk issues.


See also:

http://www.daid.ca/project.html

Final Results

Please see ‘resources’ box to the right of this page for the final report and http://www.daid.ca/project.html for more information.


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