Elmer Avenue Green Street Project Explored
July 8, 2010 § 18 Comments
A few weeks ago, L.A. Creek Freak had the pleasure of attending the grand opening of the Elmer Avenue green street project in Sun Valley. My earlier post mainly described the opening festivities, with little project information. Today’s article fills in more of the details.
First credit where credit due: This great collaborative multi-benefit project has many parents. They include: the Los Angeles and San Gabriel Rivers Watershed Council (their project website is www.lasgrwc.org/elmer ) the city of Los Angeles (multiple Department of Public Works’ Bureaus: Sanitation, Street Lighting, and Street Services, and the Department of Water and Power), TreePeople, U.S. Department of the Interior Bureau of Reclamation, California Department of Water Resources, California Water Resources Control Board, L.A. County Department of Public Works, Upper Los Angeles River Area Watermaster, Water Replenishment Distict of Southern California, Metropolitan Water District, city of Long Beach Stormwater Management Division, city of Santa Monica Environmental Programs Division, Pomona College, University of California Riverside, and Urban Semillas.
Big kudos also to Los Angeles City Councilmember Tony Cardenas and Public Works Commissioner Paula Daniels for their high-level actions in making the project happen.
The Elmer Avenue Neighborhood Retrofit Project is located in Sun Valley, in the northeast San Fernando Valley. For a map showing the project location, see Creek Freak’s earlier post. It’s one block, about 600-feet long - 1/10th of a mile – with 24 detached homes. It’s a mainly Latino, working-class neighborhood, not poor, but not well-off.
One of the things that I found impressive about Elmer is that its public infrastructure is “off the grid” in a couple of ways. Creek Freak will mostly focus on the water aspects of that (below), but the street also has solar streetlights that are not attached to the electrical grid. These are actually the first such lights in the city of Los Angeles.
Of course, they’re long-lasting energy-efficient LED lights.
The solar panels at the top of the lamppost are clear to see. Also, about a third of the way down the pole is a box, which contains the battery. There are no wires that connect this pole to the rest of the city’s electrical grid.
The water on the street is also off of the city’s “water grid” – ie: the system of storm drains connecting to creeks, washes, rivers and the ocean. Historically this street suffered from problems with the water grid: drainage problems - the street used to flood during the rainy season.
Now, all the rainwater that falls on this street (and on some adjacent streets) is captured. Nearly all of that water is infiltrated – soaked into the ground to recharge groundwater aquifers. The rest of the water is re-used.
The main device that captures stormwater is a large underground infiltration gallery – buried below the street. I like to think of it as an underground box that’s missing the floor. In this case, here’s what the infiltration device looked like before it was buried:
These are now buried – note the street level manhole cover. Runoff water flows into grated stormdrain openings at the north end of the street. The upstream openings are actually on Stagg Street – just around the corner from Elmer. Excess water flows in, settles out some trash and other solids, then makes its way down those two black pipes. The pipes are perforated, so the water leaks out into the ground.
The soils in the northern San Fernando Valley are relatively good for infiltration (they’re basically the relatively unstable San Gabriel Mountains being washed into the alluvial plains), so, with the capacity of the two long perforated pipes and the area they leak into (plus the other street features), there’s enough volume to contain nearly any storm that could come along.
All this capacity is a good thing, because there’s not really any outlets at the end of the pipes. Most projects like this might connect to a stormdrain for overflow volumes, but there’s no stormdrain in this area, so the infiltration is just off the grid.
In a deluge of biblical proportions, the underground and surface features could feasibly fill, and then stormwater would flow on the streets as it had before the project. Los Angeles City Bureau of Sanitation, Watershed Protection Division engineer Wing Tam assured me that the soil percolation is so good at the site, and the system volume so great, that this overflow should never take place.
Soaking the surface water into the ground mimics what a healthy natural watershed does. Instead of quickly sending polluted waters flooding into our rivers and creeks, projects like this send some of that water into our underground acquifers. That increases local water supply; we can pump that water up later, instead of importing so much water from faraway places – at great cost, including energy costs which contribute to global warming. It also helps us to make it easier to restore our creeks to health, because downstream from these sorts of projects, the creeks are a little less polluted and a little less flood prone.
Longtime Creek Freak readers know that I am much less into the underground gizmos, than I am into the surface manifestations that reveal rainwater processes to the casual observer. The underground devices are more expensive to install and maintain than surface interventions. For healthy Los Angeles watersheds, we’re going to need some buried devices, which do great things for water quality and definitely do offer multiple benefits.
The drawback is that these underground fixes can also put our water (and problems it too often carries) out of sight and out of mind. Water on the surface - like y’know creeks - is also more likely to provide broader spectrum of multiple benefits – improved water quality, increased water supply, decreased flood risk - plus urban greening, habitat, and an increased human awareness of and connection with natural processes going on around us. These above ground projects also increase in effectiveness over time, as plants grow and ecosystems become more complex. The gizmos tend to work perfectly on day one, then gradually get worse, and require maintenance efforts.
(A parenthetical note regarding comparative volumes: The volume of the underground infiltration galleries is about 750,000 gallons – 2.3 acre-feet. The volume of surface infiltration in the project [described below] is about 115,ooo gallons… so the underground stuff is the workhorse in this project – contributing 87% of the capacity. Hiding a lot of volume underground allows for greater concentration and centralization.)
The good news is that this project has the best of both worlds – plenty of great underground multi-benefit capacity, and also lots to see and follow on the surface, too.
The features are both in the public realm - sidewalks, parkways – and in the private realm – front yards, driveways, walkways, even rain barrel cisterns. First, let’s take a look at the public area improvements.
Prior to this project, the street had no sidewalks or curbs. Now it has both. Not ordinary ones, though. Between the curving sidewalk and curb (in the parkway), there’s a depressed area – technically called a bioswale – but basically a man-made mini-creekbed.
At the upstream end of each swale is an inlet for rainwater to flow in from the gutter.
At the downstream end is a similar-looking outlet where excess rainwater can overflow back out into the street.
Water from the street drains into the swale, where it soaks into the ground, and naturally waters the plants there. Here’s what the dry swale looks like:
and here’s a shot of the same swale full of rainwater, from a rainstrom earlier this year:
Elmer Avenue residents were engaged in the various aspects of the project; indeed, one reason the street was chosen was due to interest they showed during the selection process. The residents could choose various improvements to made on their property. Most participated; a few didn’t. Depending on what was needed and desired, different residents adopted different individualized features.
Improvements on private front yard property included installation of new waterwise native plant gardens.
Here’s a before shot of one home:
And here’s what it looks like after the retrofit was done with it:
Here’s a Where’s Waldo type game: in the after images above, you can spot rain barrels? They’re terracotta brick -colored like the photo on the left.
The barrels are filled by rain running from the roof into the downspout. Once the rain barrel fills up, overflow water runs into the depressed rock-lined swale. Rain water saved in the barrels, can later be used to water the yard, conserving water and money. Rainwater is also very high-quality, with less salts than our local tap water (which isn’t too bad.) Plants love it.
Some of the walkways and driveways were also converted to paver systems, which also allow for water to soak into the ground. In the photo above, the curved brick pathway (along the driveway) is made of permeable pavers. Water percolates into the cracks between the bricks and sinks down into a gravel bed below them.
Here’s a closer shot of a permeable driveway, being doused during the opening reception last month:
The Elmer Avenue Neighborhood Retrofit Demonstration project is an excellent project. It truly showcases many ways that we can make neighborhoods more sustainable, more healthy, more aware and how to look great while doing all that. I expect that this green street will just get better and better over time, too.
If you’re in the area, I suggest that you drop by and check it out. Especially when rain is forecasted!