21st Street Green and Complete Street
Award
Description
As the City of Paso Robles built out its infrastructure in the late 1800s, conveyance of water from Mountain Springs Creek was modified from a natural open channel to a buried storm drain pipe under 21st Street. Historic runoff from the Mountain Springs Creek watershed, along with subsequent development of the urban areas over the course of several decades, resulted in frequent flooding, poor pavement, and inadequate facilities for bicycles and pedestrian traffic.
To improve flooding issues, pedestrian and cyclist safety, and aesthetic beauty, the City of Paso Robles decided to turn 21st Street, between Vine Street and Riverside Avenue, into the first Green AND Complete Street in the County of San Luis Obispo.
Project Goals
- Reduce the frequency and severity of street flooding
- Increase stormwater infiltration
- Improve water basin recharge while enhancing stormwater runoff reaching the Salinas River and increasing sediment removal
- Improve pedestrian safety
- Reduce traffic speeds by incorporating traffic calming devices
- Add Class II bike lanes
- Increase shade and aesthetic appeal by planting trees and drought tolerant plants
- Promote infill and redevelopment
To reach project goals, drainage improvements combined bioretention for treatment of initial stormwater runoff with open-channel flow for larger rain events. These improvements reduce the frequency and severity of street flooding, increase groundwater recharge, improve the quality of stormwater runoff, and remove sediment from stormwater draining from the street.
Placement of pervious concrete pavers in pedestrian areas allows stormwater to seep into the ground. Bioretention areas were placed at the edges of the street for treatment of first stormwater flush. Drought-tolerant plantings prevent erosion and treat storm runoff biologically.
Trenches containing perforated piping amid clean rock were also installed. This retains large quantities of usable stormwater as it infiltrates into the soil. Other features include an artistic bike rack, curb bulb-outs, and flashing LED crosswalks. In addition, the City recycled old concrete removed from the project and used it in gabion walls.
Branch
