The Center is predicted to be truly net-zero water, possibly the first in the US to receive a commercial permit for drinking treated rainwater in accordance with federal requirements. Water demand calculations were performed for the building based on building occupancies, scheduled uses and design fixture flow rates in order to determine the daily water supply for the building. The design of this building includes several water-saving plumbing devices such as composting toilets, low-flow lavatories, low-flow kitchen sinks and a low-flow shower. All landscaping is native to the region and does not require permanent irrigation. Given the plentiful and consistent availability of rain, the challenge in achieving Net-zero water was primarily getting the regulatory approvals to allow treated rain to meet both potable and non-potable water demand. At the onset of design, the team met with regional representatives from the State Department of Health and the Virginia Office of Drinking Water (ODW). The design team’s challenge was to design a waterworks that met all NSF standards and state-regulations, but were appropriately scaled for a very small project, and can be maintained by an in-house staff operator on a daily basis. Two standing seam metal roofs capture rainwater, filling two 1650-gallon cisterns, enough to withstand 23 days of drought. Rainwater is filtered (four log filters) and disinfected (ozone and UV, chlorine was subsequently added and CBF is appealing this requirement), and supplies all water uses within the Center.
Composting toilets reduce water demand while also treating waste on-site. Solid compost is used on-site, while leachate is stored and sent to a local struvite reactor and converted into commercially available fertilizer. Greywater from sinks and showers is piped to a greywater rain-garden (raised above sea-level) that treats the water, allowing it to infiltrate. Excess roof runoff is diverted to raingardens that naturally filter and infiltrate runoff, managing all stormwater on site. All hardscape is composed of permeable pavers and gravel, with adjacent raingardens and bioswales to treat runoff, allowing for infiltration. The design includes a City-owned parking area north of the site that features low-impact design strategies, which has become a model for future City projects.
Photo: Courtesy of Dave Chance
