One of the few upsides to California’s drought is that it has helped reduce pollution at some urban beaches, because less precipitation has meant less runoff from city streets and other paved surfaces. This in turn means less pollution draining into streams and bays.
Urban runoff is the number one source of pollution in places like Santa Monica Bay in Southern California. But the city is not relying on drought to help stop the problem. Instead it has taken the lead in implementing solutions, like “green streets” and runoff recycling to catch urban runoff before it hits the bay.
Meeting water quality standards is one of the drivers for the city’s actions, but in some cases, the harnessed runoff is also being used to supplement nonpotable water sources, which means Santa Monica has to rely less on imported water to meet its needs.
To learn more about the city’s efforts, Water Deeply spoke to Neal Shapiro, the city’s Watershed Management Program coordinator.
Water Deeply: Santa Monica has developed an ordinance for reducing runoff leaving properties, including requirements for new construction to have an Urban Runoff Mitigation Plan. How does it work?
Neal Shapiro: I do inspections for all construction projects required to do stormwater mitigation. Generally an infiltration pit or drywell is the most common structure people chose to implement. Most of our projects, 95 percent, are single-family homes and they have enough space in the yard to put in a subsurface chamber that is filled with rocks or a plastic matrix that takes up space and will hold rainwater coming off roof and driving surfaces, directing water into an underground drywell, and then water infiltrates into the ground. We want to get the water back in the ground. Or it could be directed into a storage tank, cistern or rain barrel, and then the property owner could use it for nonpotable exterior or interior purposes.
We have rebates if people want to retrofit their property if they are not doing construction, the city offers rebates up to $1,000.
Water Deeply: Have more homeowners opted to try to catch water for storage and reuse during the drought, instead of just slowing it until it can infiltrate underground?
Shapiro: People still mostly do infiltration because it is simpler and cheaper. Otherwise it gets more complicated and expensive. But there are people that want to do that, because they have extra money and they are more strongly motivated to do a more sustainable strategy.
Rain barrels are simple and inexpensive but you have to have more hands-on management during winter because you have to drain the rain barrels before the next storm if they aren’t empty. There are automated systems that are starting to be used that can do that based on weather gauges.
Water Deeply: What’s the impact on the city from reducing runoff?
Shapiro: It helps the city because that rainwater isn’t discharged as stormwater and carrying potential pollutants. The goal is to keep the water onsite and let it infiltrate in the ground where it normally would have gone before we paved over the area with roads and rooftops.
Water Deeply: For the runoff that does make it to the streets, you also have a first-of-its-kind facility to treat that – how does it work?
Shapiro: SMURRF is the Santa Monica Urban Runoff Recycling Facility. It collects dry water runoff; it’s not a stormwater facility. It was built to prevent dry weather runoff during the summer months from getting to the beach where people could get sick playing in that water. We divert all our dry weather runoff and most of it goes to the SMURRF and it includes runoff from the City of Los Angeles, so it’s a joint project between our two cities. We treat that and we reuse it for landscape irrigation, and in a few cases for indoor flushing.
Water Deeply: What role do “green streets” play?
Shapiro: We have three green streets. Our first one includes a lot of different strategies. It has a pervious concrete parking lane on each side that helps the water percolate in the ground. It also has curb cuts so the water comes out of the gutter and goes into the depressed parkways – that landscaped area between the curb and the sidewalk – so water goes in there and then can infiltrate into the ground. Then we also have underground storage chambers under the parking lane and water goes through catch basins and goes into plastic concave chambers where the water is stored and then infiltrates into the ground.
There are different strategies you can use, it doesn’t always have to use permeable surfaces. You can just have the water go into depressed large parkways and have it infiltrate there. It depends on each site and what you have available.
Water Deeply: With limited resources, how do you decide where to put green streets?
Shapiro: Ideally you want to put them where you get the most bacterial exceedances at the beach.
We are putting a 1.6-million gallon cistern at the Santa Monica pier, so that can actually capture stormwater and then we wouldn’t need green streets there.
Right now we are doing a capital improvement project for alleys. Many alleys are resurfaced so when we do that we are putting in a pervious concrete swell down the center of much of the alley so we can get infiltration there. Every year we do about 10 to 12 alleys.
When we do have major projects to redo streets we’ll be incorporating these strategies.
Water Deeply: What other exciting projects is the city doing?
Shapiro: We have a new library, and it has our first cistern that uses the water for indoor flushing.
We also started building a new project at one of our parks, Los Amigos Park, that will take stormwater out of a stormwater pipe under the city street and will put it in a cistern under an athletic field and that water will be used for irrigation and flushing of the park bathroom.
The City of Los Angeles installed an almost 2.7-million gallon cistern underneath one of their parks and will put in a treatment system and the water will be used for irrigation of the park by the city, irrigation of their golf course and we are going to take some of that water and pump it to our Marine Park, which is on the border with Los Angeles and we’ll use it for irrigation. The water they collect includes runoff from parts of our city.
These are some really exciting projects we have to help reduce our use of potable water and make us more sustainable and help us be more self reliant on local water resources.
Water Deeply: Where does Santa Monica’s water come from?
Shapiro: Over 70 percent comes from local aquifers, many in Los Angeles. The balance of supply comes from Metropolitan Water District of Southern California, which comes from the Colorado River and Northern California. So our goal is to eliminate that imported water we are using so we are 100 percent self-reliant, the goal is by 2020.
We’re making headway toward reducing the use of imported water through additional groundwater pumping, and the use of rainwater and stormwater. We also have a program to reduce demand – we have rebates for people to remove their turf, replace spray irrigation with drip irrigation and use climate appropriate plants.
Our Sustainable Water Master Plan is getting underway and that is going to install three 1-million-plus gallon cisterns to collect stormwater and another million-gallon cistern to collect wastewater. We’re going to tap into our sanitary sewer system and mine that wastewater, treat it and then use it for nonpotable purposes. That will be a unique project for us. All of our wastewater is sent to Los Angeles for treatment now and we’re actually going to start using it for beneficial purposes.
The important thing is we hope to be self-reliant by 2020, living on the water that’s available to us locally and not having to use imported water because taking water from distant watersheds is obviously not sustainable. Hopefully we can meet that goal, and hopefully everyone else in the region can work toward that strategy.