MacKenzie Parking Lot Stormwater Infiltration Project

Stormwater and urban runoff from impervious (hard) surfaces are major sources of creek and ocean water quality pollution. Runoff from parking lots often contains pollutants including hydrocarbons, fine sediments, polycyclic aromatic hydrocarbons (PAHs), metals, nutrients, and other pollutants that are toxic to aquatic organisms and potentially harmful to human health.

By retrofitting existing infrastructure using Low Impact Development (LID) designs, stormwater is allowed to soak into the soil, mimicking pre-development conditions. By installing LID projects throughout the City, the amount of pollutants being carried directly into our storm drains, creeks, estuaries, and ocean will be reduced, improving water quality.

Project Description

Permeable pavers were installed in the MacKenzie Park Parking lot at State Street and Las Positas Road, in order to allow stormwater and urban runoff to infiltrate into the ground. The design demonstrates a retrofit that complies with the City’s Storm Water Management Program (SWMP) requirement to detain and treat the volume of water generated from a one inch, 24 hour storm event. Project construction took place from August through October, 2011.

Design

The project includes the following design elements:

• Permeable pavers installed in the area of the parking stalls.
• Pavers were outlined with a six inch wide concrete ribbon border at grade.
• Pavers were installed to replace a portion of the decomposed granite path from the parking lot leading to the MacKenzie Adult Building.
• Additional car and motorcycle spaces were added to the northern end of the parking lot.
• Two low, gently sloping speed bumps were installed in the driving lanes in order to strategically direct the stormwater to the pavers for maximum treatment benefit.
• Two planters were constructed in the middle of each of the two main parking rows and two trees were added to these planters. 
• A tree was planted in the existing vacant planter in the northwest corner of the lot.
• All existing trees in the park remained.
• The design added six parking spaces to the lower parking lot for a new total of 75 spaces.

For more information about the project, please contact Tim Burgess.

To learn more about permeable pavers, view this presentation given to City staff on September 20, 2011 by David Quinn of the Interlocking Concrete Pavement Institute.

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