Dollarton Highway Dollarton Highway Realignment ProjectRealignment Project

District of North VancouverDistrict of North Vancouver

May 12, 2006

Project Area

Maplewood MudflatsMaplewood Mudflats

Maplewood Mud Flats

Conservation Area

New Dollarton ROW

Environmentally Sensitive AreaEnvironmentally Sensitive Area

Protect a rare & vital Burrard Inlet ecosystem

Groundwater dependencies.

Water Quality.

Maplewood Mudflats Conservation Area.

Wildlife habitat & migration corridors.

Scope of the ProjectScope of the Project

New Roads Constructed.

Dollarton Highway Realignment – 1.1 km major arterial, 4 lane divided

Riverside Drive East – 0.3 km major collector, 4 lane undivided.

Other roads – 0.9 km local commercial/industrial, 2 lane undivided.

Carried out in 5 phases starting in 1999 and completed in 2003

Total cost of project approx $8 Million

Project Catchment Area – 40.6 Ha.Project Catchment Area – 40.6 Ha.

Technical RequirementsTechnical Requirements

Drainage Design

Must service the entire drainage area.

Safe disposal of storm water.

Groundwater recharge

Minimize post-development flow impacts.

Provide overflows to storm sewer for large storms

Storm Sewer SystemStorm Sewer System

Existing Site ConditionsExisting Site Conditions

Native soils - well graded sandy gravel / gravelly sand

High water table (anywhere from 1.0m to 5m below surface

Measured hydraulic conductivity 1x10-3 to 4x10-3 m/s (medium permeability)

Flat terrain – road grades from 0.5% to 3.7%

Design ConsiderationsDesign Considerations

Used dispersal drains for 49 of the 69 catch basins installed.

Incorporate groundwater recharge into the design .

Use gasketed joints for storm sewers to avoid groundwater table draw down.

Include trench dams to prevent groundwater from following trench lines to the outfall.

Typical Road Cross SectionTypical Road Cross Section

Infiltrating CB system

Catch Basin Dispersal DrainsCatch Basin Dispersal Drains

Infiltrating CB system

Dispersal Drain Plan ViewDispersal Drain Plan View

Dispersal Drain Detail

Dispersal Drain SectionDispersal Drain Section

Dispersal Drain Detail

Marine OutfallMarine Outfall

Adapted O&G Chamber design based on previous research & experience.

Design low flow bypass in sewer main to divert water into chamber when most needed.

Better treatment (TSS removal) and less frequent maintenance, virtually no re-suspension of entrained sediment.

Marine OutfallMarine Outfall

Oil & Grit Interceptor

Marine OutfallMarine Outfall

Riparian planting plan for rip rap slope between elevations 2.5 and the top of the slope

Ecopockets planted @ 1 plant per 1.5 m2 or as directed by the environmental monitor

Riparian planting stock

•Red osier dogwood

•Black Hawthorn

•Pacific WIllow

Low flow diversion weir

Oil & Grit Interceptor

Treated water outfall

Dollarton Highway west of Dollarton Highway west of Riverside DriveRiverside Drive

Dollarton Highway east of Riverside Dollarton Highway east of Riverside DriveDrive

What Have We learnedWhat Have We learned