by Mark von Wodtke, FASLA

Imagine entering Claremont from the freeways (210 or the 10) or by the highways (Base Line, Foothill or Arrow) and experiencing beautiful tree-lined streets with parkways that define our community. As we can see on Indian Hill Boulevard, street trees provide wonderful gateways that celebrate each season of the year.

Imagine living near freeways or highways but not being exposed to excessive emissions and particles that compromise health. An urban forest is an extension of our lungs that assimilates emissions and filters particulates. Trees can also diminish the dull roar from traffic on freeways and highways by muffling sound, providing habitat for birds, and voice for the wind.

Imagine capturing polluted water that runs off pavement fulfilling the requirements of recently approved water pollution regulations (MS4) in cost-effective ways. By pruning some pavement, we can create bio-swales that retain rainwater and digest contaminants before they get into storm drains and run off into riparian areas, lakes, beaches and the ocean. We can use some of the runoff we capture to irrigate street trees and parks, and provide ground-filtered water to feed the wells that Claremont depends upon.

Imagine living in an oasis where the tree canopy reduces the heat island effect for the whole community and not just the Village where our community’s founders have had the vision to plant and nurture the urban forest we benefit from today. This green infrastructure assimilates carbon dioxide and releases oxygen. Recycling green waste can include producing biochar which, when used to amend soil, sequesters carbon for thousands of years. Biochar enhances soil ecology for a healthier landscape. It can also filter water in bio-swales, which clean up pollution that runs off pavements.

All of this is possible if we adopt a storm drainage concept inspired by “keylining.” Developed in Australia to make dry land more productive and reduce flooding, keylining uses vegetation-filled drainage ways to capture runoff and support the growth of trees.

Keylines can be laid out in Claremont to capture water that runs off the alluvial cone that our community is built upon. These keylines would help Claremont adapt to drought and more intense rain storms that are likely to occur with a changing climate.   

The first keyline, where bio-swales percolate water, could be along Base Line Road. This could support many street trees that could mitigate sound and emissions from the 210 Freeway.  It would also clean up water before it goes into the detention basin that was built next to Base Line Road, just north of the 210 Freeway. Water from this basin, which flows down the storm drain in Indian Hill Boulevard, could fill retention basins that could be built in city parks and Rancho Santa Ana Botanic Garden to provide water for irrigation. It may be possible to add reclaimed water to this system to provide more consistent water for irrigation.

The second keyline could be along Foothill Boulevard, the historic Route 66 that has evolved into a local highway and collector street. Pruning some of the pavement to create bio-swales would provide space to capture runoff and plant more trees that could enhance this gateway to the community. This could be tied into the water treatment facility proposed for the Claremont Colleges.

The third keyline could be along Arrow Highway. Here again, bio-swales can capture runoff in planter areas that support more trees to enhance this gateway.

And a fourth keyline could be along San Jose Street, which could capture more runoff and have more  trees to buffer the 10 freeway. Even more sewage water could be reclaimed there.  Growing vines on the sound walls would reduce the reverberation of noise from the freeway.

We have the opportunity to begin doing this by leveraging money the city has received from Caltrans to renovate Foothill Boulevard. This provides Claremont with matching funds for grants from the Flood Control District, Air Quality Management Control District and other funding sources. Let’s build a team of professionals to successfully implement the keyline concept. 

With careful design, bio-swales can include bike paths on permeable pavement to create a safe bicycle-enhance network (BEN) along highways. The team of professionals hired to develop a Master Plan for Foothill Boulevard, needs community support for including keylining with bio-swales to sustain more street trees. 

We also need our city to accept the recommendations of the Tree Action Group of Sustainable Claremont and hire an urban forester with a budget to develop and implement an urban forest plan that uses keylines.

Keylining our green infrastructure throughout Claremont could become a model for human ecosystems applying regenerative design for sustainable development, following principles identified by the visionary John T. Lyle.

The bottom line is that we could improve our quality of life by making Claremont an even nicer place to live if we use imagination to get beyond complacency with the current status quo.   Claremont could manage its water resources—improve its potable water supply, conserve storm water and salvage reclaimed water from sewage—to become less dependent on imported water,  and at the same time do more to live up to its reputation as the beautiful City of Trees.