Assessment RFP 06-17 (released July 2017) SRD Requested: - - - PowerPoint PPT Presentation
Oyster River / Glenmore Dike Assessment RFP 06-17 (released July 2017) SRD Requested: - Condition Assessment - Geotechnical Assessment (incl. Seismic) - Conceptual Upgrades & Cost Est. We proposed to provide the above, plus : -
Condition Assessment - Findings
Unauthorized Recreational Users (ATV / Dirtbikers) have caused minor damage via erosion of accessways Debris Blocking Drainage Channels Vegetation Overgrowth has caused
Reduced Access to Some Areas
Geotechnical Assessment via Drilling
Seismic Stability Assessment
Hydrologic Assessment via Statistical
Hydrotechnical Assessment via 2-D
Ex. Glenmore Dike Hydrology & Floodplain Mapping were Completed in early-1980’s
WSC Flow Data for Oyster River @ Woodhus Creek
Pre-1980 Flow Data Post-1980 Flow Data
Hydrology – Design Flow Rate Determination
Statistical Analysis of ~40 years river flow data
Q200 = 493 m3/s
Climate Change Impact
Precipitation Increase to 2090 = 15%
Design Flow Rate = 567 m3/s (200-Year Return
Period Flow, plus Climate Change)
Estimated Future Precipitation Change Due to Climate Change for the Strathcona Regional District (Data from PCIC’s Plan2Adapt Online Tool)
2-D Hydraulic Modelling using HEC-RAS software
(see videos)
Hydraulic Modelling Findings
Matches Observations from December 2014 “Emergency Dike Repair” & Validates Need for Repair
Priority 1: Maintenance & Repairs
Vegetation Clearing & Replacement of ex. Culvert (incl. new Flap-Gate Chamber) Est. Cost = $138k (plus $7,000 annual maintenance)
Priority 2: Upgrade & Raise Dike at North End
Upgrade the “emergency repair” section to proper dike standard (approx. 90 meters of dike length to
be re-built)
Est. Cost = $303k
Priority 3: Dike Re-build for Long-Term Seismic Stability
In order to completely upgrade the dike to be seismically stable, approximately 510 meters (in addition
to the 90 meters from Priority 2) would be re-built.
Est. Cost = $3.775M
Many dike assessments are done piecemeal. However- concurrent, multi-disciplinary assessments
(Condition, Geotech, Hydraulics) led to efficiency in upgrade recommendations based on the sum of all findings, for example:
Culvert replacement, requiring local dike re-construction; Area around culvert was identified as seismically unstable; Extend extents of dike re-construction around culvert to improve seismic stability; Hydraulic assessment determined dike crest could actually be lowered at this location, leading to savings
compared to re-build to existing height.
Budget
Budget cap was determined by grant funding. SRD scope in their RFP included condition & geotechnical
assessment.
We felt there was sufficient funding to complete additional hydraulic / hydrologic assessment, and all works
were completed on-time and within budget.