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Commercial Potable Rainwater System at Brock Environmental Center

Case Study by Juliet Grable and Cameron Tull
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Commercial Potable Rainwater System at Brock Environmental Center
Photo Credit Prakash Patel Photography, courtesy of SmithGroupJJR
Plumbing Systems
Rainwater Harvesting for Potable Use
Non-chlorine UV purification system
Virginia Beach, VA
Dan Horne, Engineering Field Director, Office of Drinking Water
The Chesapeake Bay Foundation
Commercial-Retail/Office
10500
SmithGroupJJR
Hourigan Construction
Biohabitats
Living Building Challenge
11/14/2014

Abstract

The Chesapeake Bay Foundation’s Brock Environmental Center serves as an embodied ethic of environmental stewardship and a prime example of cutting-edge regenerative design in the built environment. While this fully Living Building Challenge (LBC) certified structure has no shortage of innovative features, it met state and federal Waterworks requirements to become the first commercial building permitted to collect, store, and treat harvested rainwater for potable use.

Permitting Process

In order to meet the Imperatives for LBC’s Water Petal (Net Zero Water, Ecological Water Flow), the design team knew they would need to gain the permitting necessary to harvest, store, and treat rainwater for potable use. To do this, the Brock Center became a ‘public water works’ as defined by the state of Virginia. State and Federal regulations require certain treatment methods and operation standards that would have violated compliance with the LBC’s Red List (use of chlorine) and been untenable economically (expense of a required on-site operator). Fortunately, the Foundation hired SmithGroupJJR, the water system engineer, and Biohabitats, a water systems specialist, to consult on code navigation and act as intermediaries between the design team and the approving officials. The compliance path involved a slow but continual process of proving the safety/efficacy of the design’s non-chlorine treatment process. They conceded to regulators’ concerns when it came to keeping the fire suppression system connected to municipal water, and reached a compromise on a safe yet economically viable solution to the required on-site water works operator. The Brock Center’s permit for harvesting rainwater for potable use was approved the same day that the building officially opened, November 14, 2014.

Code RequirementCompliance Path
Virginia Waterworks Requirements outline purification and operation standards for processing surface water into potable water. 2.3.10.5 Variance Process highlights steps necessary to appeal/apply for a variance to the code. CBF was granted a variance that lowered the required classification for their on-site water works operator, and allowed for certain non-Red List materials be approved and supplemented into the system
Federal Safe Drinking Water Act is the overarching guideline for potable water standards and requires certain purification/operation methods be employed. SmithGroupJJR, Biohabitats, and Paul Willey worked with regulators throughout schematic and design/build phases to meet federal standards. Municipal water would supply the building’s sprinkler system, a third party water testing agency (MSA, PC) would conduct monthly quality assurance, and the requirement for residual presence of 0.2 mg/L chlorine in potable water was appealed.

Project Description

The Brock Environmental Center, which serves as the Chesapeake Bay Foundation’s (CBF) regional epicenter for education, outreach, and restoration efforts, was registered under Living Building Challenge 2.1. At that time, the Standard broke the Water Petal into two Imperatives: Net Zero Water, which stipulates that all water used in a project must come from captured precipitation, and Ecological Water Flow, which stipulates that all wastewater and stormwater must be managed on-site. The Brock team faced both technical and regulatory challenges in meeting the Water Petal requirements.

Perhaps the most significant and difficult regulatory obstacle that the Brock team encountered was the permitting that would allow the Brock Center to harvest and treat rainwater for potable use. The team presented the proposed rainwater system to the Virginia Department of Health – Office of Drinking Water (ODW) during a preliminary engineering conference in November 2012 but were met with extreme skepticism. Paul Willey, Director of Education Operations for CBF, realized the need for a champion – someone who would work with the permitting agencies regularly – and took on the role.

The team had originally hoped to acquire the permit by the time they broke ground on the project, in August 2013. But the process took much longer. In February of 2013, Dan Horne, Engineering Field Director for ODW, sent a letter stating that the system as proposed would not be accepted because it did not treat water to federal and state potable standards. He also expressed concerns about the possibility of cross-connections among city water, rainwater collection, and the Brock Center’s potable water system.

In June 2013, SmithGroupJJR submitted the Preliminary Engineering Report for the rainwater collection, treatment and distribution system. The report described the roof material, vortex filter, and cistern design, and detailed the “treatment train,” which consisted of a turbidity pre-filter, a membrane “ultra-filter” and UV light disinfection, but no chlorine disinfection.

In October, Horne replied: 1) the system as designed did not provide the disinfection method that meets the State’s potable water standards, which rely on chlorination rather than UV disinfection and requires residual chlorine levels of at least 0.2 mg/L; 2) the filtration and disinfection equipment would have to be verified by a qualified third party; 3) the proposal would have to address how the fire suppression system (fire sprinklers) would be supplied, and how it would be designed to prevent backflow; and, 4) Virginia Department of Health – Office of Drinking Water (ODW) needed to be able to test the source water before it underwent filtration and disinfection; in particular, the agency was concerned that the rainwater might be too acidic, in which case it could potentially corrode pipes and equipment.

In February 2014, the team sent its revised design, which included chlorination as an additional and final step in the treatment process. This revised report also clarified that the fire sprinkler system would be connected to municipal water and would be totally separate from the rainwater system. At the same time, the team sent a formal appeal to ODW, requesting that the agency approve the system without chlorination, as originally designed. Throughout this period, Willey acted as “squeaky wheel,” regularly checking in with ODW on the application’s progress.

According to Virginia Department of Health, a system that collects, stores, treats, and distributes high quality and safe (potable) water is considered a waterworks. Because the Brock Center serves at least twenty-five people for at least six months out of the year, but not necessarily the same twenty-five people, the Brock Environmental Center is classified as a Transient Noncommunity Waterworks. This classification mandates that a Class IV state-certified Waterworks Operator be on-site to oversee the system and conduct the required sampling and monitoring. To remedy this, Chris Gorri, the Building Operations Manager for the Brock Center, agreed to take on the responsibility of becoming a Class IV Waterworks Operator. The training for his certification included a six day class at Virginia Tech.

The team did not know for certain whether they would ultimately receive permission for the system as it was designed. If it was not approved, they would have had to compromise with a hybrid system that relied on treated rainwater for nonpotable uses and municipal water for potable uses. It was not until November 14, 2014 (the morning of the Brock Center’s official opening) that CBF received notification that its permit had been approved.

Additional Resources:

Whole Building Design Guide Case Study of Brock Center, 2/3/17, by National Institute of Building Sciences. Trim Tab Magazine Case Study on The Chesapeake Bay Brock Environmental Center, 5/12/16, by International Living Future Institute.
Brock Environmental Center For a Living Chesapeake: Building a Sustainable Legacy for the Bay, book by Juliet Grable.  2017, EcoTone Publishing Water Petal Case Study, The Chesapeake Bay Brock Environmental Center, September 2016, by International Living Future Institute.

Motivations:

CBF has pioneered the Chesapeake Bay’s restoration efforts for close to 50 years. Throughout that ongoing journey, the foundation has also been at the forefront of ecologically sensitive design and construction practices. From their first environmental education center near Annapolis (built in 1972) to the Philip Merrill Environmental Center (2001), forever remembered as the first LEED Platinum building in the world, and now the fully Living Building certified Brock Center, CBF has certainly embodied its commitment to environmental stewardship.

As CBF President William C. Baker states: “One critical component to our ‘Save the Bay’ strategy is building smarter, with less impact on the land and the water. This approach has been a hallmark of the Chesapeake Bay Foundation’s efforts to restore the Bay to a much healthier state through a vigorous, planned, and committed process of regeneration” (Forward). It is this commitment that proved to be the strongest motivator for the CBF team.

Design / Build Process

cs_brock_03.jpg
Image courtesy SmithGroupJJR
The team first focused on estimating the Brock Center’s daily water demand and exploring ways to reduce that demand. While estimating demand for CBF’s staff was relatively straightforward, doing so for thousands of potential visitors was trickier. SmithGroupJJR worked with CBF to estimate the number of visitors and predict how much they would use the facilities inside the Brock Center.

Next, the team focused on reducing demand. Right off the top, the choice to use composting toilets cut estimated water use by over two-thirds, saving nearly 50,000 gallons per year. Other strategies included specifying low-flow fixtures for lavatories and sinks and using recycled water for non-potable applications such as irrigation. After all of these strategies were factored in, the team estimated daily water demand for the Brock Center at a modest 145 gallons. This figure represents the combined use of all lavatories, mop sinks, water coolers, kitchen sinks, and showers.

SmithGroupJJR’s engineers estimated water supply using rainfall data gathered from the Norfolk International Airport between August 1, 1948 and June 19, 2013. Unlike many regions in the country, there is no shortage of precipitation in Hampton Roads. Norfolk receives an average of 45 inches of rain per year, with little variation from month to month, and historic data shows that drought in Virginia Beach rarely lasts longer than three weeks. Consequently, the cisterns were sized to accommodate 3300 gallons (just over a three-week supply).

To comply with the State of Virginia drinking water regulations, the cisterns used in the Brock Center’s systems are made from polyethylene, meeting National Sanitation Foundation (NSF) requirements, and are located below the building in a mechanical room. Situating the tanks underneath the building enables a system that relies mostly on gravity to move water, which saves pumping energy and ensures the system can continue to operate during power outages. But it also means the cisterns are not highly visible, although tours of the building usually include a trip to the cistern and composting room. A single ‘pickle barrel’ cistern next to the main entrance ramp and adjacent to the education pavilion sends a demonstrative message to visitors that rainwater collection is one of the Brock Center’s important water strategies. The rainwater collected in this cistern provides irrigation water to new plantings in a nearby rain garden, along with teaching opportunities.

Waterworks System Specifics (Ecological water flow journey at Brock Center):

tumblr_nilm5vWIUx1rwffgyo1_5001.jpg
Photo by Dave Chance
The Brock Center’s waterworks starts with the sky. Rainwater is collected from 5,500 square feet of roof area, including the south-facing roof that includes the flush-mounted photovoltaic modules. Although the Galvalume roofing material is not certified to NSF Standard 51, which governs potable water catchment areas, the team was able to provide documentation from the Texas Water Development Board. Specifically, the agency’s Texas Manual on Rainwater Harvesting cities Galvalume as an acceptable surface from which to collect rainwater.

The 3:12 roof pitch is steep enough to ensure that dust and debris do not get trapped in the seams or pores; the slope also facilitates rinsing during the first flush of a rain event. Rainfall flows down the roof and into a continuous gutter; from there it funnels into one of two centrally located downspouts. The gutters include leaf guards to minimize debris entering the water. To comply with the Red List and ensure the quality of the water, the solder used in both the gutters and downspouts is free of lead.

A vortex filter uses centrifugal action to direct the first flush of rain to a rain garden located right next to the south deck. After the first flush, rainwater flows into two 1,650 gallon cisterns located underneath the building. A pump circulates ozone through the cisterns to prevent algae growth. From there, water flows into the building and into a dedicated closet west of the lobby. In order to meet the strict requirements of both the EPA and the State of Virginia, the collected rainwater undergoes a series of treatments that reduce turbidity and disinfect the water. The first of these is a pre-filter, which removes particles from 25 microns down to 1 micron; from there it enters a pleated cartridge charged membrane filter, which removes particles down to 0.01 microns. Next, water undergoes UV disinfection before being treated with chlorine in the final step.

After chlorination, water is pumped into a loft above the closet and into a tank that contains calcium carbonate. This mineral increases the pH of the water so that it does not leach copper from distribution pipes. From there, water flows into a 300-gallon pressure tank, which provides water to the rest of the building at 45 to 50 psi. Carbon filters which remove the chlorine are provided in all drinking water fixtures at the point of use.

Cost / Benefit

The purchase of Pleasure House Point (the 118 acre piece of waterfront property that the City of Virginia Beach and CBF jointly purchased) was a win-win-win for all parties involved (City, CBF, public). Due to a crashing housing market in 2009, the $30 million dollar property dropped to $19 million and was then negotiated down to $13 million at which point the City and CBF decided to jointly purchase it. The City of Virginia Beach would put down $4 million from their Open Space Fund, securing 108 acres into mostly a conservation easement (84 acres) and city park land (24 acres). CBF would put down $1 million for the ten acres that would become the site for the Brock Center. The remaining balance was met through a variety of grants and loans. This buyout effectively saved the Pleasure House Point property from becoming a large-scale development of some 1,100 highrise condos and townhouses, the intention of the initial property owner prior to the housing crash.

Aside from the cost of land, and “excluding sitework costs and the premium to elevate above the floodplain, Brock's construction costs were just over $400/sf (including renewables). The Living Building Financial Study, found LBC-certified, mid-rise office buildings in hot-humid climates incur a premium 26%–31%. Brock's cost premium was in this range” (Project Results).

The requirement for an onsite water works operator initially seemed untenable economically, as the expense for a highly specialized technician was high. Due to the size and projected occupancy of the building-scale water work, regulators agreed to allow a lower classification of operator to tend to daily and weekly water system checks/operation while a monthly specialist, MSA, PC, would conduct more rigorous analysis of water system safety and performance. This variance allowed the building manager, Chris Gorri, to become appropriately certified for the on-site operation requirement thus removing the economic burden of hiring an expensive technician.

Lessons Learned

Regarding Rainwater Systems: In June 2014, staff at the Brock Center started to notice a metallic taste in the water, which after testing revealed slightly elevated levels of copper. This points to an underappreciated factor when utilizing rainwater systems: that rainwater is typically ‘soft’ and has a low dissolved mineral content which means it can readily attract certain elements.

As rainwater flowed through the copper distribution pipes at the Brock Center, it was dissolving copper into the water. CBF remedied the problem by adding calcium carbonate to the cisterns to harden the water; however, this may have caused the expensive charged membrane filter to clog quickly. As an alternative solution, CBF added a treatment step after filtration. A calcium carbonate reactor tank next to the pressure tank now treats the water, raising the pH and hardness enough so that it does not attract copper from the distribution pipes.

Project teams should understand that pioneering water systems will inevitably require more time, extra expenses and requirements that may seem redundant. For instance, the Virginia Department of Health requires residual chlorine to be part of the treatment train. The State also requires an on-site state-certified waterworks operator and frequent turbidity monitoring. Finally, the system must be connected to the city’s potable water system, which translates into additional materials and increased cost. As regulators become more comfortable with alternative systems, future project teams may not be saddled with the costs associated with having to provide these redundant municipal connections.

Teams should be prepared to start early and to build in extra time for the education and permitting process, and to find a champion to keep the process moving.

Treatment systems provide many teachable moments, and teams should be prepared to embrace these opportunities. With patience and persistence, oversight officials and contractors start to become believers, and in some cases, advocates.

Regarding Wastewater Systems: As with the rainwater system, patience and persistence were required to educate permitting officials about both the greywater system and the composting toilet system. In this case, CBF’s past experience (in particular with the Merrill Center, a 32,000-square-foot building that relies exclusively on composting toilets) went a long way to instilling confidence in permitting agencies.

Again sharing similarity with the rainwater system, regulatory officials required “back-up” measures for both the leachate and greywater tanks. Both tanks include connections to the city sewer system, complexity which adds extra cost and materials.

Updates

Performance Outcomes:  Actual water use at the Brock center is approximately 50 gallons per day, much lower than the predicted usage of 145 gallons per day. A lower water demand makes for a more resilient building. Less energy is required to pump and treat water. System components (filters, for example), will last longer, since they are processing less water per day. The cisterns and leachate tank can accommodate storage for a longer period, without changing in volume.

The energy load associated with treating rainwater is lower than expected, in part because the building’s water consumption is so much lower than was predicted. In addition, most of the energy required to treat rainwater is spent circulating ozone through the cisterns in order to keep the water clean and dissuade algae growth. The team assumed the ozone circulation pump would run eighteen hours each day, but as CBF discovered, much less pumping is required to keep the water clean, especially when the cisterns are not full and when temperatures are colder.

The wastewater systems are working as well as expected. Signs in the bathrooms instruct users to add a pinch of sawdust in the toilet after each use. This simple action keeps the composters aerated, so the compost does not have to be turned as frequently. The leachate tank is emptied four times a year, and the leachate is sent to the Nansemond facility. Compost is raked several times a month. Once the system biologically establishes itself, finished compost will be harvested from each unit once a year.

Project Contacts
Owner: Chesapeake Bay Foundation 757-622-1964 Approving Official: Dan Horne, Engineering Field Director City of Virginia Beach, VA Office of Drinking Water 757-518-2679 Architect/Engineer: Susan Arneson SmithGroupJJR 313.442.8460
Builder: Hourigan Construction 757-499-3434 Author: Juliet Grable 541-778-8174
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