Sustaining a City, Sustaining Hope: Water and the Santa Monica City Hall East

One of the ways to sustain hope during a time of crisis is to lead by example. This is an especially valuable method for raising expectations and optimism when it comes to a precious resource like water.

Editor’s Note: We’re excited to share this story from guest author Heidi Creighton, AIA, LEED Fellow, WELL Faculty, Fitwel Ambassador, and Associate Principal of Sustainability at Buro Happold. We are grateful for Buro Happold‘s sponsorship of our annual Living Future Conference, as well as next week’s Equity + Affordable Housing Summit.

The Santa Monica City Hall East building in Santa Monica, California, has been designed to meet the most exacting criteria for sustainability, resiliency and long-term cost-effectiveness. An inspiring model aimed at efficient operations, a healthy and productive workplace, and positive contributions to one of America’s most successful communities, this new municipal operations center supports the city’s commitment to sustainability with the pursuit of full Living Building Challenge certification – adhering to the most exacting standards for carbon neutrality, zero waste, and water self-sufficiency.

The Water Petal presented among the most daunting goals given the drought-prone location of the project. In an era of global climate crisis, the design team’s approach included a few key precepts such as: realigning how water is used onsite, that water be respected as a precious resource, and that the building’s water needs can be fully met on site. Early steps included a detailed analysis of water use patterns, considering climate change projections, as well as understanding the carrying capacity of the City Hall East building site and its surroundings. The project solutions respect the natural ecosystem and hydrology of the site, with effective systems for capturing, purifying and reusing water.

In 2014, the City’s team began the design of the new, 50,000-square-foot City Hall East with a team including prime contractor Hathaway Dinwiddie Construction Co., the architect Frederick Fisher & Partners, and engineer and Living Building consultant Buro Happold. The City of Santa Monica’s team included project manager Amber Richane, construction manager Tim Purcell, and Chief Sustainability Officer Shannon Parry. These leaders were directed by the City Council to lead their staff in exploring the feasibility of meeting the Living Building Challenge. If successful, the new City Hall East building would be the largest and first-ever municipal project to meet the LBC. It will also be the 4^th full Living Building Challenge building that Buro Happold has completed.

Codes, Legality and Land Use

The next three years of design offer a valuable case study in achieving net zero water for the green building community. Many of the ideas the project team developed raised issues of code conformance, legality, and land use regulations. As the International Living Future Institute (ILFI) asserts, “Reaching the ideal for water use means challenging outdated attitudes and technology with decentralized site- or district-level solutions that are appropriately scaled, elegant, and efficient.”

In practice, this statement sets up a massive challenge for any project team to achieve. In this case, the City Hall East design team ultimately worked to overcome overwhelming obstacles presented by building, health and water codes to permit this project to meet the spirit and the letter of the Water Petal. More than 30 meetings with agencies ranging from city, county, state and even federal jurisdictions created layers of challenges that almost prevented Santa Monica from achieving its net zero water goal. Obscure code references and conservative interpretations required the design to constantly evolve. The design team developed creative solutions to meet schedule and budget requirements, while limiting risk associated with nontraditional code compliance processes.

Ultimately, the City’s leaders persevered, and they received a permit that includes California’s largest installation of composting toilets and the first building in California to treat rainwater for potable use on site including drinking water.

Merging Three Water Strategies

Three separate water strategies collectively allow all the building’s needs to be met by minimizing use and through water harvested on site, while ultimately “creating a positive impact on the human and natural systems that interact with them,” as the International Living Future Institute eloquently states.

First, the projected water and sewer demand for the building was cut by half with the introduction of a foam-based composting system for all the lavatories.  The system units are located in the basement of the structure and require periodic maintenance. Second, for potable water uses, rainwater from the roof is captured in a 40,000-gallon cistern located beneath the building; in drought conditions, the rainwater system is supplemented by groundwater pumped from a well drilled on site. All rainwater and groundwater is treated with a combination of cartridge filters and granulated active-carbon filters, also located on site. Lastly, for nonpotable water uses, a system captures greywater and condensate from the cooling system’s air-handling units, which is treated via a moving bed-membrane bioreactor and is used for onsite irrigation.

Metrics and Water Budget

To get to a net zero energy and water building, the project team led by Joseph Coriaty FAIA, and Mariam Mojdehi,  AIA, from Frederick Fisher & Partners, along with Buro Happold’s David Herd  and  Julian Parsley, P.E., worked with the City of Santa Monica’s project team to detail a very specific understanding, during design, of how the building would be used. For a project with such high sustainability aspirations, it is especially important to understand occupant behavior, occupancy schedules, and plug loads. The team responded with a passive approach to the design that makes the most of all available natural resources.

One design goal was to make this an efficiently used building, with more opportunities for the City of Santa Monica to benefit from each square foot. In terms of energy use, plug loads are high due in part to significant printing needs of Santa Monica’s busy permit center as well as the computing power required by staff members active with geographic information systems (GIS) mapping of utilities and other information across the city. Based on surveys of staff, it was certain that many occupants would commute by bicycle, driving up water demand for shower use.

In Southern California, design teams should assume drought conditions for nine months out of the year. This means that creativity is essential in sustaining an effective water approach. Water budgets – see charts 1 and 2 below – provide critical inputs on opportunities and challenges early in the design process: area charts show project demands, while the bar charts show opportunities for collection and reuse. The water budget revealed that irrigation would be a large portion of the demand – highest in warm months when there is little rainfall. On top of the seasonal watering demands, the restroom water use (even with low and ultra-low flow fixtures) also looked high. To get to net zero, a foam-based composting toilet system – which uses only 3 tablespoons of water per flush – emerged as an essential strategy.

The project team’s projections showed that rainwater capture for potable needs offered a clear and significant opportunity, but this type of system had not yet been permitted in California. The analysis also illustrated a surplus of greywater in the winter months. Site stormwater couldn’t be recycled for drinking water, and it tends to fall on this region in months when irrigation demands are low. This led to a strategy of infiltrating as much as possible on site and sending excess water to two adjacent buildings for use in their irrigation. These solutions have allowed the project to meet the intent of this imperative which is ‘to meet all water demands within the carrying capacity of the site using scale-appropriate strategies that respect natural hydrologic flows.’

Building Water Systems

Our water budget and design ultimately incorporated the use of composting toilets, with greywater captured for urban agriculture irrigation demands. The rainwater-to-potable approach meets some of the irrigation and potable water demands for the City Hall East, enough to exclude any topping up from an adjacent well. That meant that on a net basis, the building would use more water on site than it would collect, but that potable water needs of adjacent buildings in Santa Monica’s historic municipal complex are offset with the stormwater export.

As an overview of the rainwater-to-potable solution, rainwater is collected from the roof and from PV canopies that shade parking spaces on site. Every surface used for rainwater capture and treatment for potable use has been tested for the NSF protocol P151 or had demonstrated prior use on other approved projects. The Bullitt Center in Seattle had undergone NSF testing for their PV array, and they shared that analysis with the Santa Monica team to satisfy the authorities having jurisdiction (AHJs). The TPO roof system had to be tested as there are a minimal number of roofing systems tested to NSF P151.

From these surfaces, rainwater is directed to a 40,000-gallon cistern in the basement through a system of roof drains and components all suitable for potable water use — anything the water touches must comply with California’s Division of Drinking Water (DDW) rules for components meeting potable water standards — and the rainwater is then treated and distributed back for potable use. In drought conditions, well water is available from ground sources about 50-60 feet underground for addition to the cistern.

Water Use Reductions and Efficiencies

For further water use reductions and efficiencies, the Santa Monica City Hall East utilizes a greywater system collecting everything from the showers, lavatories, and condensate. The greywater sources are treated and then used to irrigate everything on the south of the site and the courtyard, with the exception of anything within 100’ of the well.

The composting toilets save about 270,000 gallons of water per year and they also produce nutrient-rich organic materials, called biosolids. All sanitary wastewater is treated on the building site, and biosolids are exported offsite for composting. Leachate — the liquid that passes through the matter and extracts soluble or suspended solids — is pumped out and drains by gravity to the street sewer, along with miscellaneous sanitary wastewater. The leachate is handled offsite at the Hyperion Wastewater Treatment Plant, where it will be treated through anaerobic and aerobic biodigestion to create a sustainable source of heating and power for the wastewater treatment plant.

Composting and Sustaining

Among the most positive outcomes for the Santa Monica City Hall East project was working with the Los Angeles County Department of Public Health for a successful pilot of the team’s approach to composting toilets. The new building allows for potential challenges in the system – for example, the system is designed with a connection for conventional toilets if they are needed in the future. Yet the county officials are very optimistic and supportive of the pilot, and they provided ample guidance and articulated concerns to reflect the greater community and environmental needs. For example, they provided critical input about the leachate, which had to be routed to the sanitary sewer. Following the county’s input and assent, Santa Monica’s Building & Safety Division reviewed and approved the systems.

The team invested in various studies to ensure the safety and integrity of our approaches. These included an application for alternative means and methods, an engineering report demonstrating safety and performance as compared to a conventional system, and reviews by an industrial hygienist. The latter was very helpful in securing approvals. The AHJs also visited other similar facilities around the country to better understand the water system impacts and operations, and ultimately they created rigorous, comprehensive approval processes that offer a valuable model for other localities around the United States. A lengthy 12-month permitting process for the Santa Monica City Hall East was the result of design changes required by the AHJs. Their input led to additional, creative engineering solutions including raising the discharge stack height, a dedicated odor-control system, ultraviolet lights, and fan systems on emergency power. We also incorporated CO2 sensors and alarms, special safety equipment, and a cleanroom vestibule at the composting room entrance.

In 2018, California Governor Jerry Brown signed a bill to develop statewide regulations for on-site water reuse – a step that enables local governments like Santa Monica to take the lead in increasing water reuse for a more sustainable future. Pilot projects like these are essential for sustaining hope in places and times when a global climate crisis is exacerbating concerns about water resources and they pave the way for others to take similar actions.