A couple months back I stayed at the Plumpjack-owned Carneros Inn in Napa County. A more bucolic location you could not imagine, but beyond its tasty fare and sylvan setting, the Carneros has a deep commitment to sustainability. I got the tour from facilities manager Dan Philbin when I was there, and we recently spoke about the Inn's wastewater treatment facility, an on-site exemplar of water catchment and reuse. Here's what he had to say about making the most of the resources you have.
What degree of water recuperation do you have at the Carneros Inn? Do you capture as much as you use? More?
Our actual capture of domestic water is probably around 95 percent. The five percent loss would come from domestic water used to water plants, wash windows, and other domestic uses where the water does not drain to the sanitary sewer system. Due to I and I (inflow and infiltration) which is very low and rain water captured by the outdoor shower pans (also very little) we operate closer to 100% recovery. For the most part we get two uses out of every gallon of water.
How does the water recycling system work?
The wastewater treatment plant is a Zenon Membrane Bio-Reactor (MBR). All of the sanitary sewer lines on the property gravity drain to two holding or equalization tanks on the bottom part of the property. From there the waster is pumped into our WWTP by grinder pumps. There are screens that it flows through to remove any large solids that might compromise the membranes. From there the waste passes into an anoxic tank that is devoid of oxygen. From here it is re-circulated into the membrane tank. This tank has blowers that provide it with air to maintain a high dissolved oxygen ratio. The bacteria that live in this tank are aerobic and need the oxygen to survive. This also helps eliminate odor. Inside the membrane tanks two trains of membrane cassettes are suspended. The Zenon membranes consist of thousands of strands of porous hollow core fibers that are 6 feet tall. They are connected to headers top/bottom. These headers are connected to permeate pumps which produce a small vacuum (12 psi). These membranes separate the MBRs from conventional WWTPs. The pores in the fibers have a diameter smaller than viruses and bacteria so it presents a physical barrier. The pores are also smaller than suspended solids. This produces very high quality water (CA Title 22). From there the water is chlorinated and delivered to the hilltop pond (or transferred to the lower pond) for storage.
Did you look to other places for your inspiration on this system? Other hospitality locations? Other places in Napa that work to recycle their resources?
I wasn’t involved in the early stages of specifying the system. On-site treatment was a necessity for the development of the project as there was no opportunity to tie into municipal water or sewer. The City of American Canyon has had the similar MBR technology for their water and wastewater for several years longer than the inn. When our system was built this technology was mostly used in larger scale municipal plants. MBR technology is also frequently used on cruise ships due to the compact footprint.
To what degree do you see environmental protection as your responsibility? Any chance California Lt. Governor and Plumpjack founder Gavin Newsom and his take on staying green has an effect on that?
We take stewardship of the environment very seriously. We also use best practices and ensure that we create as little impact as possible. This is one of the core philosophies of Plumpjack as a whole.
Any other green features in the construction or energy use that are as unique as the water capture system?
All of the climate control in the guest cottages and the homes on property is done via water source heat pumps. There is a 300-foot deep bore under each cottage (four beneath each home). Inside the bore is a looped 1-inch diameter pipe. The loop is filled with water that is re-circulated. The heat pump uses the earth as a heat sink to provide warm or cool air to the unit. This system eliminates the noisy (and energy hungry) condensing units found around most properties. The result is a much quieter property with reduced energy consumption. Also, the hot water for the cottages all comes from a central plant and re-circulated underground to each unit. This is more efficient than 86 remote water heaters.
One of my favorite design elements, and one that I imagine speaks to your water recycling program, are these funny little yellow fire hydrants with purple tops. What do they do?
The yellow fire hydrants with the lavender caps are charged with recycled water processed by our waste water treatment plant. The fire department requested that the caps be colored to signify that it is not potable water. Lavender piping is used to denote recycled water piping so we painted the caps lavender. We are not connected to municipal water or sewer so we have an on-site diesel fire pump that provides all the fire protection water.