Inside Seven
Current Issue: September 2014
Part of the Department's water conservation efforts involve the use of drought-resistant plantings, such as this accent tree called Chorisia speciosa (Silk tree).

by  Judy Gish
Issue Date: 08/2008

From recycling to mulch, Caltrans landscapes hold on to their water.

The last time that Southern California faced serious water shortages, in 1991, the California Department of Transportation (Caltrans) got the memo and began taking steps to reduce usage.

This time around, Caltrans is way ahead of the game, having already put into practice many water conservation measures with even more in development, said Senior Landscape Engineer Ed Siribohdi. Among the measures are:

Using drought-tolerant/native plant materials as much as possible and particularly in new planting; using recycled materials to create mulch, which helps to retain water; directing irrigation to individual plants wherever geography allows, as opposed to spraying an entire hillside or large area; and putting sprinklers on an automatic clock and fitting them with rain sensors to stop water flow when rain is detected (although they are frequently damaged or removed by vandals, Siribohdi said).

Very important to the program is the use of recycled wastewater for irrigation. District 7 currently has 62 recycled water sites and is working on a pilot project to convert two existing water meters to recycled water meters off the San Diego Freeway (I-405) in Sherman Oaks.

Two other pilot projects involve an irrigation controller conversion at the Golden State Freeway (I-5)/Pasadena Freeway (SR-110) that will allow maintenance workers to operate and monitor water usage from the maintenance yard and a project to combine innovative irrigation techniques, hardscape or permeable surface off U.S. 101 in the Hollywood area.

Siribohdi has experienced the entire era of water conservation, having started working at Caltrans in the Design Division in 1991, where he remained until 1999. Currently with Maintenance Design, Siribohdi said he is more or less of a liaison between Design, Maintenance and Construction. It is a pivotal job, as District 7 maintains more than 9,000 acres of landscape areas.

Another direction Caltrans is exploring is the use of “hardscape,” Siribohdi said, citing an example at the San Bernardino Freeway (I-10)/San Gabriel River Freeway (I-605) Interchange. There are many advantages to designing freeway-adjacent areas that are aesthetically pleasing but contain little or no vegetation, including reduced water use and maintenance requirements.

It seems like it could be an ideal solution for this semi-arid region but Siribohdi said it probably wouldn’t appeal to a lot of people who want and expect a lush landscape. Also, despite the fact that it saves maintenance costs, the initial capital outlay is steep: $50 per sq. ft. vs. $2 per sq. ft. for plantings.

In any case, freeway vegetation is here to stay: “Freeways are the landscape of the city,” Siribohdi said. “Freeway landscape is like a big park, an oasis here where there is so little green space.”

Even so, with water conditions worsening, that oasis is getting harder and harder to sustain. Right now conservation measures are recommended but not mandated. Next year could be a different story, he said, “when it will be critical that we do better.” The reason: northern California is cutting back on the water it sends us and the Colorado River is steadily losing water, Siribohdi said, predicting that “We’ll be squeezing out every last drop.”.

Glass mulch, shown here off U.S. 101 near the 4-level interchange, is made of recycled material. It is being used in hard-to-maintain areas.  Senior Landscape Architect Ed Siribohdi helps to ensure that Caltrans saves every drop of water possible. This hardscape is off Route 134 near Forest Lawn. It provides aesthetic interest while requiring no irrigation and little maintenance. Weed mats, made of recycled tires, can be placed under guardrails to control unwanted vegetation, saving not only maintenance costs but also water.