Tag: Los Angeles

Looking for some good news about climate change?

Posted on by nancysteele

In a month of some truly depressing news about the environment and climate change, a bright spot appeared. But first, here are two illustrations of the trouble we are in.

In early April, we read that the Arctic may be completely free of summer-time sea ice within a decade, as this graphic cleverly illustrates:

Arctic Sea Ice

The reason for the Artic Sea Ice Death Spiral is apparent when you look at the continuing upwards march of atmospheric carbon dioxide levels, as reported in early May by Andrew Revkin.

Keeling Curve, Mauna Loa

Truly depressing news, eh? Is anybody listening? Are we all doomed? It’s time for some good news, something that gives a little bit of hope.

Apparently, young people don’t drive as much, anymore; the bloom is off American’s love affair with cars and this can only be a good thing. Researchers believe this is a stable, long-term reduction in miles driven that started in 2005, before the beginning of the Great Recession.  People age 16 – 34 have reduced average miles driven by 23% from the 2005 peak.  Even higher income young people are driving less, evidence that this is a behavioral choice unrelated to the cost of gas.

We can only hope for more good news as the world changes.

The Los Angeles River in one word

Posted on by nancysteele

We asked people to describe “The LA River Today” in one word. Here’s what they said:

When we asked people to complete the sentence “I want the LA River to be–” with one word, we heard some inspiring wishes.

What two words would YOU use to describe the Los Angeles River?

How to create a clean water alley, Part 4

Posted on by nancysteele

Flooded Paseo North Entry BeforeAs we mentioned in an earlier post, the reason we are converting the Paseo into green infrastructure is because it receives water from about 20 upstream acres of land and the soils and geology are ideally suited to infiltration to groundwater. During larger storms, water picks up speed as it flows into the alleyway. Thus, we needed to design something to slow the water down before it hits the bio-swale.

The Forebay reduces the erosive force of water entering the bio-swale. It also allows sediment and litter carried with the water to settle out. The forebay elements include a river rock cobble bed, a weir, and a river rock cobble apron for the weir.

The river rock cobble bed at the forebay entry creates an obstacle course of sorts for the water entering the bio-swale; water slows down as it moves over and around the river rock cobble. Slow moving water is less likely to erode soil and has more time to soak into the soil – exactly what we want to happen in the bio-swale.

Concrete pour for weir
Concrete pour for weir

A weir is a low dam built across a water course to regulate the flow of water.  The weir is constructed of concrete and separates the river rock cobble bed from the bio-swale; it regulates the amount of water entering the bio-swale through the channel at the bottom of the weir and its low walls.  When there is a small volume of water, it will flow through the 12 inch wide channel at the bottom of the weir. When larger volumes of water enter the river rock cobble bed, water will continue to flow through the channel but the low wall of the weir will hold back water until it is at a height that it is allowed to spill over the walls. Eventually all the water moves through or over the weir.

The cobble apron on the down-side of the weir protects the bio-swale from the erosive force of water moving through the channel or spilling over the weir. When water flowing through or over the weir hits the cobble apron, its velocity or energy is dissipated or spread out over the cobble so the water entering the bio-swale is moving at a slower, gentler rate that is less likely to cause erosion.

Before the river rock cobble bed and cobble apron could be constructed, we needed to complete construction of the concrete entry and weir. The construction crew refined the grade elevation points for the entry, forebay, and weir. The concrete pour for the entry and weir went smoothly. We have a few more steps to get through before you can see the finished forebay, however, so hold on for more.

Concrete pour for entry
Concrete pour for entry

to be continued

How to create a clean water alley, Part 3

Posted on by nancysteele

Now that the infiltration trench and bio-swale have been constructed, it is time to lay the sidewalk, which goes on top of the infiltration trench. How’s that, you say? Putting a sidewalk on top of the place where water is supposed to soak in? For the Paseo, we installed pervious concrete but even if we had used regular cement, it still would have worked as the system is designed to receive water from the bio-swale underground.

The Pervious Concrete Pathway winds its way from one end of the Paseo to the other, providing a pleasant and safe path. Pervious concrete has ‘voids’ or gaps that are created when the fines are removed from mix thereby allowing water to flow through the concrete. Water falling on or over the pervious concrete will flows through these spaces to the infiltration trench below it. To begin construction of the Pervious Concrete Pathway, a course of gravel was spread out over the infiltration trench and areas of the exposed impervious liner.

DSCN2844

Unlike Portland cement concrete, pervious concrete sets up quickly. Many hands were needed to pour, spread, smooth, and score the concrete. The choreography of material and work was impressive that day and kudos to Rudy and his crew at J&M Contractors for a pathway many will enjoy.

To aide in the curing process and protect from errant soil or debris, the completed pathway was covered with plastic sheeting. Below you see the completed pervious pathway along with one of the landscape boulders.

Next up is construction of the Forebay, an important element of the design to protect the bio-swale from erosion and clogged soil.

To be continued

How to create a clean water alley, Part 2

Posted on by nancysteele

In Part 1, we showed the initial steps in constructing the infiltration and bio-swale. Part 2 illustrates the complex choreography of marrying the infiltration trench and the bio-swale.

The majority of water entering the Paseo will be directed to the bio-swale, which will filter and allow water to infiltrate the soil and migrate to the infiltration trench.  To maintain the function of the infiltration trench, we need to prevent soil from the bio-swale from filling in the voids and gaps. A geotextile – a tightly woven material – both helps prevent soil from moving into the infiltration trench and allow water to move into the trench.

The crew placed a layer of geotextile on top of the base layer of gravel and marked it to indicate where the edges of the infiltration trench and the bio-swale met.  One side will have soil and the other will have gravel.

The challenge when backfilling the trench with gravel and the swale with soil is to maintain the vertical edge of the geotextile. To achieve the vertical profile of the geotextile, the crew placed plywood on edge to create a vertical guide. On one side of the plywood, a course of bio-retention soil was placed, then the geotextile that lay in place on the trench was “flipped over” the plywood guide to ‘cover’ the bio-soil layer and a course of gravel was spread out, then the geotextile was ‘flipped over’ the course of gravel and a layer of bio-soil spread out.

This sequence continued until the heights of the bio-soil and the gravel met the desired elevation points. The crew started in the center of the Paseo and worked out toward either ends of the Paseo. Kudos to the Paseo’s Field Superintendent Jose Esquivel, American Landscape, who masterfully choreographed the complicated logistics required for the delivery of gravel and soil and the work of spreading the materials.

To be continued next week.

Loving the Los Angeles River

Posted on by nancysteele

This summer, a few hardy souls “owned” the LA River by kayaking a 1.5 mile stretch in the Sepulveda Basin. Tickets were available for about six minutes on an early July morning for the trips in August and September. I had the good fortune to go in early September and two of the Council’s staff, Kristy and Derek, paddled on the last weekend, courtesy of the Conservation Corps’ Paddle the LA River program.

Derek has been working for the Council this summer, so I was especially glad he was able to go on one of the last trips this year. Here is his account:

“It was a busy day on the Sepulveda Dam Recreation area. Parking lots were full, soccer fields bellowed with the cheers of family and teammates, and cyclists raced around the numerous bike paths. The atmosphere was the perfect setting as I and a handful of others were about to embark on the last kayak tour of the LA River for the year. With Ranger Tim and his contagious energy, we set off to our launch point under the Balboa Blvd Bridge.  As we climbed into our vessels, aided by members of the LA Conservation Corps, a rush of exhilaration set over the group. We were on the LA River, a privilege few citizens have experienced.

George, leader of Paddle the River, guided the first segment of the trip upstream in order to make sure everyone was comfortable in their kayak or canoe. I, as representative of the Council for Watershed Health, explained the importance of watershed wide approach to improving our rivers.  After this, we soaked in the sights, sounds, and allure of the river for the next 1.5 miles. The banks were lined with willows, castor bean, sycamore, and cattails. A gentle breeze swayed the vegetation as the sun began to break through the clouds. I was on the lookout for birds when I spotted a snowy egret resting a branch. It barely noticed me and posed, but only for a moment as I managed to snap a few shots before it flew off. It was only until I saw a shopping cart poking out of the water that I had a realization: I was in Los Angeles, in an urban setting with the 101 freeway nearby, and I completely forgot. It was amazing how quickly the river can consume your thoughts, even though it is far from revitalized.

As we finished our trip in the shallow waters close to the dam, we all looked back at the river as if to ingrain the river expedition into our memories. Our experience was unforgettable, and left us wondering how long we would remain as the privileged few who have paddled the LA River.”

Sustainable Los Angeles?

Posted on by nancysteele

The vision of the Los Angeles & San Gabriel Rivers Watershed Council says that by 2025 “the Los Angeles region has become a model of sustainable urban watershed management.” This vision is the conclusion of a long list of criteria of sustainability that were adopted in 1996 and reaffirmed in 2008 by the Board of Directors of the Watershed Council. You can read the complete vision statement on the Watershed Council’s website. It is a very ambitious vision.

Let’s set aside for a moment the deadline of 2025. Does sustainability even make sense for an urban region like Los Angeles? Are the criteria for sustainability achievable? And there is that deadline. I’m sure in 1996 it seemed comfortably far away, but the future is rushing towards us. No one knows what the world will be like in 2025, but we can imagine. I’ve read plenty of dystopias, thank you, and I would prefer to work towards utopia, even if I believe it to be unrealistic. I grew up watching Star Trek, afterall.

This blog, then, is a place to explore the idea of sustainability in an urban city – who, what, where, when, and especially how.