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6. Minimize impervious surfaces Watershed quality decreases rapidly when the total impervious area exceeds 10%. Yet typical single-family housing projects have 25-50% impervious surfaces. Asphalt and concrete for parking lots and driveways can be formulated to be porous. Crushed rock and mulch add a striking element to the design while allowing water infltration. Pervious pavers which can include low growing groundcovers or gravel also facilitate water infltration into the soil. ^ Keep impervious surfaces to a minimum: Use porous surfaces, including permeable paving, and maximize landscaped area to encourage infltration. ^ Avoid contiguous impervious surfaces. Do not directly connect impervious areas to the stormdrain. ^ Decrease parking lot sizes by narrowing the aisles between rows and increasing the ratio of compact to full size spaces. For more information contact the Center for Watershed Protection at www.cwp.org: ^ Remove all unnecessary impervious paving. Go to www.StopWaste.Org or check with your local hauler for more information on where to recycle asphalt & concrete. L ~i 5 Q O F C I a Appropriately planting more trees decreases runoff and protects water quality. Trees also absorb air pollutants, thus protecting air quality. Dollar for dollar, larger trees deliver 8 times the benefts of smaller trees. "In the City of Berkeley's Parks, Recreation and Waterfront Department we do not use any pesticides. As an Arborist, I mainly deal with tree issues, and with most insect problems I face, the insect is gone in a week or so. It's like having a cold. It passes. " - Jerry Koch, Arborist, Parks Recreation & Waterfront Department, City of Berkeley p@TVlO11S COACT@f@ Pervious concrete is a high cement content mix manufactured with a low water-cement ratio and without fne aggregate that: ^ Meets NPDES regulations ^ Provides for groundwater recharge ^ Has the same structural integrity as conventional concrete When compared to a conventional asphalt parking lot requiring stormwater system tie-in and frst flush pollution measures, pervious concrete parking lots are by far the lower initial cost solution. SOURCE. I'EliVl(JUS CONCI>l_ /V=. CONCRETE PROMOTION COUNCIL OF NORTHERN CALIFORNIA, WWW.CPC NC.ORG. b i... ti ~ ~ ww~~~... •~i,~ ~ ~ 47 7. Plant and protect trees Trees can intercept significant amounts of rainfall each year and thus help control stormwater runoff. The Center for Urban Forest Research estimates that the the continuous tree canopy in Oakland intercepts 4 inches of rain over one acre in a typical year -about 108,000 gallons.Their root growth also increases the ability of soil to take in rainfall. ^ Select trees that match the microclimate and soil characteristics. ^ Select California natives or other low water use species. ^ Specify large stature trees in as many appropriate places as possible. ^ Plant in groves and hydrozones. ^ Provide adequate soil volume, amended as per a soil analysis. ^ Inspect tree health regularly. ^ Maintain and prune appropriately. ^ Design the landscape to protect 80% or more of existing, mature, healthy trees and include penalties for destruction of protected trees in the construction contrail. Increasing porous surfaces decreases runoff, protects the biology of the San Francisco watershed and contributes to the restoration of our local streams, creeks and wetlands.