Application of Porous Pavement May 12, 2006 Richard Boase, P.Geo., CCEP North Vancouver District A Water Balance Perspective

Why Change at All Why is this an issue? How do we implement effective change? How do we monitor results of decisions made?

Single Family Rainwater Mgt. DNV encompasses 16,237 Ha. (63 mi. 2 ) 64.5% Wilderness Area 19.5% Residential 8.3% Urban Parks 3.3% Conservation 2.1% Industrial

Single Family Rainwater Mgt. Population approximately 80,000 27,319 dwelling units (incl. M/F) 70% detached single family 11% increase in dwelling units

Single Family Rainwater Mgt. Science tells us that watershed health begins to deteriorate as a watershed moves beyond 10% total impervious surface area.

Aging SFD stock >50 years Lower land value Different appreciation for space Total lot area = 1901 sq. m. 19% Hard Surface 53% Tree Canopy 15% Landscaping 13% Building Footprint

New SFD stock < 10 years Higher land value Different appreciation for space Total lot area = 1972 sq. m. 24% Building Footprint 25% Hard Surface 23% Tree Canopy By Covenant 28% Landscaping

59% increase88% increase

Single Family Rainwater Mgt. How do we implement change?

Single Family Rainwater Mgt Rain Data (mm) Over 80% of rain = small frequent showers < than 50 mm We need a new approach

Single Family Rainwater Mgt. Site Watershed Health WBM Building size Hard surface Landscaping

Single Family Rainwater Mgt. Yes we can make a difference if we have; Policies Bylaws Standards for “greener” designs

Pervious Paving We needed something to give us a nudge Who would ever have thought it would come from a simple Council discussion over a routine lane paving project!

Pervious Paving Open Graded Asphalt Hot mix asphalt with inter-connecting voids Developed as a highway safety feature to reduce hydroplaning, skidding and tire noise

Pervious Paving Could we adapt an existing use of open graded asphalt? Used as a tennis court surface Well draining More use year round

Pervious Paving Project Area 550 m 2

Pervious Paving Geotechnical Assessment First Variable permeability rates ( mm/hr) High fines content (18 – 45 %) Organic content under existing lane surface

Pervious Paving Geotechnical Assessment First Flat topography No ability to raise grade Concern about capillary action & fines

Pervious Paving No alternative but to excavate and install a suitable sub base layer 300 mm thick base course 25 mm gravels with < 5% fines (75µm) 75 mm layer open graded asphalt

The End