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Oakwood Watershed Venice Garden

23:07 Aug 8 2014 Brooks Avenue, Venice, Santa Monica, Los Angeles, California, 90291, United States of America

Oakwood Watershed Venice Garden Oakwood Watershed Venice Garden Oakwood Watershed Venice Garden Oakwood Watershed Venice Garden Oakwood Watershed Venice Garden Oakwood Watershed Venice Garden
Description
Abstract

Working locally can transform a street, a neighborhood and even a whole city. Architect Isabelle Duvivier was inspired to push the limits by creating Los Angeles County’s “greenest home” when she transformed a dilapidated 100-year old home. The house resides in a long established low income neighborhood on Brooks Ave. in Venice, California. Her solution was holistic. Every part of the house from building materials to energy and water-use were examined for maximum efficiency. What resulted was a LEED Platinum house and a 2012 Outstanding Home Award from the United States Green Building Council (USGBC). Experimental opportunities such as greywater applications, 95% native plants, collection cisterns for irrigation, net-zero energy and material reuse were investigated and used. One hundred percent of storm water was collected on site including runoff from an adjacent property. One of the project’s greatest achievements was controlling how and where water was distributed and reused. The gardens were designed to create a haven for local wildlife, a spot for orchards, farming, and a distribution center to provide produce to neighbors. The heat island effect was reduced through landscaping and minimizing the hardscape. The house and garden acts as a laboratory for ‘sustainable’ gardening. Duvivier even boosts educational signage about green building throughout the property. Looking into the future, Duvivier is designing a sustainable neighborhood plan by reimaging the streets and alleyways as part of a broader green infrastructure network that will include permeable paving, street trees, and play areas.

Sustainable Goals

Isabelle Duvivier, a local Venice California architect wanted to make a big difference in environmental practices in her community when she purchased a dilapidated house on Brooks Ave. in Venice in a low income neighborhood. She went about renovating her 100-year old house from top to bottom, inside and out with experimental and scientific fervor. Duvivier’s goal was to reduce the impact of the house and garden on the environment through intelligent design choices related to water, energy, and material use. Duvivier built a LEED Platinum dwelling and created the greenest house in Los Angeles County and was recently honored by the United States Green Building Council (USGBC) with a 2012 Outstanding Home Award, which recognizes innovative multi- and single-family projects that have demonstrated leadership in the residential green building marketplace.

Every part of the Brooks residence, a 1700 square foot remodel and addition to a 1912 Craftsman Cottage, was examined and designed to be as green and energy efficient as possible using most of the current technologies and experimental opportunities available. She included the natural environment by creating a habitat for birds, bees, butterflies and education opportunities for friends, clients, and neighbors.

The Brooks house became a personal learning laboratory and a means to experiment with new technologies.

Adaptive Reuse in a Historical Neighborhood
Rather than tear down the 100-year old house in which generations have lived, Duvivier remodeled and modernized her craftsman house, keeping the integrity of the bungalow streetscape. Integration into this high density, low-income neighborhood was important. The sailing form of the new second story harmoniously blends with the existing house while respecting the architectural history and scale of this traditional beach neighborhood. A vegetable garden was created in the south-facing front yard to encourage casual discussion around the sharing of food. Giving food to neighbors became a common practice. Whenever possible, she hired local workers to decrease commutes and infuse revenue and jobs into the local economy.

An overall site plan was developed early-on, zoning the garden into different types of habitats, water requirements, roof runoff opportunities, and indoor water availability. . The entire site is designed to either allow water to permeate into the ground naturally or to be collected for reuse later. The goal was to increase the efficiency of stormwater/greywater reuse, introduce elements of beauty into water delivery systems and provide habitat diversity without the need for imported water. The principals of Low Impact Development (LID) were used even though at the time of the permitting of this project, these City of LA requirements were not yet in place.

Off-site water sources
Water sources include seasonal off-site runoff from an adjacent neighbor and the rear alley that drains four immediately adjacent, impermeable, high-density housing projects. Another water source includes all project seasonal roof run-off. And the last water source is the frequently flowing greywater from the ultra-low flow interior bathroom fixtures.

Infiltration devices installed on site
Due to the site topography and the compacted soils, in the past, rainfall would be directed toward the house and due to the elevation change would end up collecting under the house. To eliminate this problem, the site was modestly re-graded to direct water away from the house. It should be noted that though the site was re-graded, no soil left the site in order to reduce the waste impacts. Instead a small hill was created, specifically a landscape feature later coined Sage Hill. A gravel filled trench drain and several Eco-Rain boxes were installed along the west and front property lines to direct water away from the house towards the front of the property where it could be infiltrated. In the rear east side of the property a swale was created and planted with trees. In the front east side the concrete from the original driveway was cut out and vegetated with fruit trees and perennial herbs. Those measures were taking to infiltrate site and off-site surface run-off.
In order to infiltrate run-off from a portion of the building, a 850 G. rain garden was also installed in the rear yard to collect run-off from 34% of the roof area. This rain garden is landscaped with California native plants, which enjoy seasonal drenching. There is also a lovely water wheel sculpture and fountain that slows the water down and makes an artful statement before the water disappears into the garden. Trex decking and DG were used to allow for infiltration on outdoor walking and entertaining surfaces.

Water Collections – Cisterns, First Flush Diverter
Two cisterns were installed that together collect 800 gallons of rainwater. These two cisterns collect the 66% of the roof run-off that the rain garden doesn’t infiltrate. One cistern waters the fruit orchard using a manually operated gravity-feed drip irrigation system. The other cistern services as a seasonal fish habitat and a flower garden. Both cisterns and their accessories (first-flush diverter, rain chains, and downspouts) are artful and positioned for functionality and visibility.

A first-flush diverter was created that would be prominently displayed and oversized. This device is placed on the downspout to divert the first several gallons of rainwater away from the collection container, to overflow into the adjacent vegetation. The initial water is dirty from roof pollution, bird droppings, and other loose matter. The design works in such a way that heavier material will drop straight down into the diverter instead of the cistern. The standard ones available are uninteresting and often made of vinyl. A beautiful custom-built devise was created that is integrated into the downspout and cistern collection area. It is highly visible so as to be used as an educational example showing how it works to all who visit the site.

The second cistern collects less water, only 300 G, than the other but it is a living laboratory for the little people who live in the house. While it is used to water a small flower garden in the front west corner of the property, it provides learning opportunities and requires much on-going experimentation. It is an open-air cistern that provides habitat for fish, plants and insects.

Making Water Visible – Rain Chains and Waterwheel
One of the goals of this project was to make water visible by creating and displaying artfully made beautiful water accessories, such as custom-made ornamental rain chains, a water wheel in addition to the cisterns. It was seen as an important part of the site design to promote dialogue and understanding about hydrology and watershed management.

Greywater
A greywater recycling system is connected to most fixtures in the house except the kitchen sink, dishwasher, and toilets. This water gets pumped in a 1’ pipe to the riparian trees, water loving plants, as well as the banana crescent. The water flows into a Hydotech Aqua2use tank that instantly pumps the water into the garden. Water is never stored in the tank. It flows out directly into the garden. There is an overflow to the sewer in case of a malfunction, as well as a valve that can turn the whole greywater system off.

As previously stated, the site is organized by location of water sources, both rain water and greywater. It is a not a good green building practice to introduce water close to the house. Irrigation and moisture near the base of a house will encourage mold, rotten wood and termites as well as has the potential to undermine the foundation. Deciding where to use greywater requires careful consideration. Not only do you want the plants to be away from the house, but you need to choose plants that like the appropriate water regiment.

There are approximately seven native riparian trees that are regularly irrigated by the greywater system. Each tree is surrounded by a 1’ deep by 3’ mulch field and has an adjustable valve to adjust water levels. These tree species include: Populus fremontii (Cottonwoods), Alnus rhombifolia (White Alder), Platanus racemosa (California Sycamore), Salix lasiolepis (Arroyo Willow) plus five non-native varieties of banana located in the banana crescent at the end of the greywater line.

Habitat
Plant communities found on the property are native chaparral, riparian shrubs/trees, fruit orchard, berry patch, banana crescent, and vegetable garden. The backyard is a formalized version of the natural world where native plants are aesthetically pleasing and serve a function: conserving water and providing sustenance for native organisms. One cistern collects rainwater used to irrigate a fruit orchard and the other is an open-air cistern with a habitat for fish that subsequently irrigates the cut-flower garden. There is a vegetable garden in the front yard that encourages discussions with neighbors about growing organic food while building community spirit and sharing food. At the top of the driveway, next to the garage, concrete was removed to build a tree house [more like a lifeguard tower.] Next to the tree house a fig tree was planted with berry vines under it, so one day the tree house might actually have a tree in and/or near it. In the backyard is a vegetated swale/dry creek that fills seasonally with over 850 gallons of rainwater. Ninety-one percent of the plants on the entire property are native plants that are drought tolerant and thus rarely need to be watered. These plants also provide a critical habitat for native fauna and insects that exotic plants do not.

There are approximately 106 species of butterflies in Los Angeles. Eighty-five of those species require native plants to survive, based on centuries of co-existence and species interactions. The same is true for birds and insects. To attract these native organisms, a wide variety of native species were planted. These include five types of Salvia and Ceanothus; three varieties of Ribes, several types of Dudleyas, Heucheras, Mimulus, and shrubs and trees such as Lyonothamnus floribundus. Prunus ilcifolia, Carpenteria californica, and wild flowers. Special species were planted include: Comarostaphylis diversilolia, Aristolochia california.

Non-natives planted for food and source food for the bees are housed in an on-site top-bar beehive. These plants include apple, plum, peach, and citrus fruit trees, borage, rosemary, many perennial herbs, and vegetables.
Team collaboration between many subcontractors was essential to the creation of an efficient water distribution system inside and outside of the home. The plumber, in tandem with the greywater engineer, contractor, and landscaper, developed an intelligent greywater distribution and overflow system, which was fine-tuned to accommodate overall landscape and specific plant requirements and flow rates.
The sheet metal subcontractor and artist collaborated with the cistern company, landscaper, and drip irrigation professional to develop a water delivery system for many different water sources. Through collaboration, the team managed to tap the expertise of each individual, resulting in a better project and educating all the team members as the work progressed.
The Building
To improve energy performance, this passive solar house has lots of natural lighting, carefully placed windows, solar tubes, and skylights, as well as natural ventilation so there is no need for air conditioning. Combined with high-efficiency appliances and Energy Star lighting (95% LED lights), the result is a home that is 53% more efficient than Title 24, the State of California’s Energy Requirements. There is a 4 kW solar array that produces a power surplus ten months of the year.

One of the most important aspects of the green design is called QII or Quality Insulation Installation, which is a technique to properly insulate a home thereby improving overall energy performance. This technique was used on this house, and is a requirement of all LEED certified building, as well as Energy Star Homes. It is a very effective way to reduce leakage by avoiding the loss of air space within the fiber or smashing insulation around pipes and electrical conduit. As a result the insulative quality of the insulation is increased. It is easy to do by a trained professional and needs to be verified by a accredited third party green building expert known as a HERZ rater.

Materials for Interior of House
Materials were used in an ultra efficient manner to reduce the need for source material and reduce waste. The stair treads, doorjambs, and bookshelves are made from laminated 100-year-old 2x4s reclaimed wood from the few walls that were removed. The existing Douglas fir floors were restored. In order to reduce material sent off to a landfill, the old cellulose insulation was composted on site and no soil was removed from the property. In the backyard, re-grading the site to divert water away from the house created the sage hill. High recycled-content products were selected including the exterior siding, bathroom tiles, concrete countertops, insulation, and the foundation. In total, 76 percent of construction waste was reused instead of going to the landfill.

Observations
After two years, we observed the following:
Overall
• No rainwater has left the site since the BMP’s were implemented. Additionally, runoff from the neighbor’s property and some runoff from the alley and sidewalk are also absorbed.
• Grading has successfully eliminated water from collecting at the base of the house or under the house.
• Native vegetation has attracted a wide diversity of bird and butterfly species and created great habitat for the bee population on site.

Rain garden
• The vegetated swale/rain garden has absorbed 100% of all its share of the runoff.
• Storm events that produce more than 1 ½ inches of precipitation or multiple events over the course of a couple of days create a small pond that persists for one to two days before being absorbed into the soil.
Cisterns
• While the two cisterns often overflow (into the infiltration trench drain) after the third consecutive storm event, the large rainwater cistern is empty by mid-summer when used bi-weekly to irrigate the fruit trees. The site could have used bigger cisterns, but due to space constraints, a larger above grade one was not possible. To install an underground cistern it would have been necessary to install a pump, which due to maintenance and longevity was less desirable. The current gravity-fed irrigation system works great.

Greywater
• There is much more irrigation water available due to the greywater system than was first expected and planted for. Sycamore, willows, cottonwoods, and alders were planted at about 3-4 feet tall and after two years, they have grown to 18 to 23 feet tall due to the constant irrigation from the greywater.
• Additional riparian plants and the banana crescent, were added to the system to use up some of the abundance water.
• Several of the finest filters from the greywater tank were removed to allow passage of more course material.

Next Steps
With the house and garden now complete, Duvivier is looking beyond this site toward the entire neighborhood. With a group of neighbors, Duvivier is looking to grow green infrastructure into the surrounding neighborhood, alleys, and street networks. She has drawn-up preliminary plans to start a conversation about this with the neighbors and policy makers. This predominantly multi-family, low-income, mixed-race neighborhood is extremely park poor. There are many neighborhood children who have neither front nor backyards and consequently, a lot of activities, such as soccer, basketball, and bike riding take place in the alleys. Most apartment buildings have no views, little landscaping and are completely impermeable creating a river of water in the alleys during rain events. And to make matters much worse, this neighborhood is under the Santa Monica Airport’s flight path, dumping pollutants from the planes onto the community.

Duvivier’s long-term plan is to obtain funding to create a network of green alleys that will be designed for permeability, capturing storm water, landscaping, trees, and play spaces for the community. Along Brooks Avenue the plan calls for creating a street tree network to absorb air pollutants and provide shade; paving changes to increase permeability and slow traffic; and widening sidewalks to accommodate this pedestrian-oriented neighborhood. In the alleyways the plan includes improvements such as landscaping, tree planting, permeable paving, as well as creating places for basketball-playing, cycling and other outdoor kid-friendly activities.

LEED Platinum - Leadership in the Built Environment

The Leadership in Energy and Environmental Design rating (LEED), consists of a suite of rating systems for the design, construction, and operation of high performance green buildings, homes, and neighborhoods. The Brooks Residence received the highest rating, which is a Platinum LEED. A total of 109 points ranks this home within the top 10 LEED rated homes in California and the top 25 LEED rated homes in the US. Both on the inside and the outside of the Brooks Residence, the architect, Isabelle Duvivier demonstrates leadership by expanding the conversation on green building techniques and water reuse.
Additional Data
Permeable ground - How large is your OFG area? (in sq. ft.): 3000
Water saved - How much have you reduced your water bill? (percent reduction): 50%
Runoff prevented - How much runoff is captured, e.g., roof, driveway? (in square feet): 1000
Share your plant list: To attract these native organisms, a wide variety of native species were planted. These include five types of Salvia and Ceanothus; three varieties of Ribes, several types of Dudleyas, Heucheras, Mimulus, and shrubs and trees such as Lyonothamnus floribundus. Prunus ilcifolia, Carpenteria californica, and wild flowers. Special species were planted include: Comarostaphylis diversilolia, Aristolochia california. There are approximately seven native riparian trees that are regularly irrigated by the greywater system. Each tree is surrounded by a 1’ deep by 3’ mulch field and has an adjustable valve to adjust water levels. These tree species include: Populus fremontii (Cottonwoods), Alnus rhombifolia (White Alder), Platanus racemosa (California Sycamore), Salix lasiolepis (Arroyo Willow) plus five non-native varieties of banana located in the banana crescent at the end of the greywater line.

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