|
A Napa Valley luxury resort turns to an onsite system to treat wastewater and reuse it for irrigation and fire protection.
By Dan Rafter
As executive director of the Napa Valley Conference & Visitor’s Bureau, Beth Carmichael knows just how important it is for businesses in this part of California to waste as little water as possible.
Napa Valley is home to both famous wines and opulent resorts. But it’s also a region of the country where water is extremely scarce, a natural resource as valuable as any.
This scarcity of fresh water is why Carmichael is so pleased with the efforts of The Carneros Inn, a luxury resort located among 27 acres of grapevines, farmlands, and apple orchards in Napa Valley’s Carneros wine-growing region. But unlike the tourists that flock to the inn, it’s not the flat-panel televisions, wood-burning fireplaces, or limestone countertops in the suites’ bathrooms that most impress Carmichael.
No, Carmichael is more interested in the resort’s onsite membrane bioreactor wastewater treatment plant. The plant recycles its treated wastewater, even sending a portion of it to a neighboring business, all to help ease the strain on the region’s notoriously limited water supply.
And while that may not be as sexy as the resort’s onsite spa or gourmet dining options, the water treatment plant is far more important to the health of Napa Valley.
“This water treatment plant is so unique,” Carmichael says. “This year, we’ve had some international visitors come to the plant. They were interested in changing out some of their own campsites into luxury facilities, into something like The Carneros Inn. They were excited by the depth that particular resort has gone to in supporting the sustainability of the community.”
The inn uses its treated wastewater to irrigate the plants and shrubs surrounding it. It also stores some treated wastewater for fire protection and funnels additional water to a neighboring vineyard.
To Carmichael, such steps have made The Carneros Inn a welcome Napa Valley neighbor since its opening in November 2003.
“We believe that the inn is a great example of a development that has really made a conscious effort to support the good stewardship of the land while creating a sustainable tourism development that services our guests here in the valley,” Carmichael says.
“Water is always an issue here in Napa Valley,” she adds. “We are an agrarian destination. People have a tendency to forget that the high-end product we produce comes from farming. Farming is a key aspect of our culture here. And we have to conserve our water to keep this agrarian society going.”
A Growing Resort
It didn’t take The Carneros Inn long to expand after its 2003 opening. Last year, the resort, buoyed by a steady stream of guests, entered into its phase-two expansion, adding a new restaurant, meeting rooms, and a fitness center. The expansion also included 17 fractional cottages, also known as time-share units.
 |
Photo: The PlumpJack Group |
| Treated wastewater irrigates plants and shrubs like these on The Carneros Inn property. |
With this expansion also came the need to add to the resort’s already impressive onsite wastewater treatment plant. The resort’s original membrane bioreactor plant was designed to treat a maximum of 40,000 gallons of water per day (gpd). From its opening, the onsite plant actually treated an average of about 20,000 gallons daily, says Dan Philbin, the resort’s director of facilities.
With the plant’s expansion—which engineers and construction crews have already completed—it can now treat a peak flow of 80,000 gpd. Philbin estimates that the plant has treated 25,000 to 30,000 gpd since the resort’s expansion.
None of this came as a surprise to anyone. Resort officials always planned that The Carneros Inn, due to its ideal location and upscale amenities, would one day expand. Philbin and his peers also knew that their onsite wastewater treatment plant would do the same.
“When we originally designed the plant, we designed it as a scalable plant,” Philbin says. “We always knew that additional membrane capacity could be added to it.”
The expansion also means that the onsite plant will continue its short history of recycling wastewater. By doing this, the plant conserves overall water in the region; Inn officials do not have to use fresh water to irrigate the approximately 8 acres of landscaping surrounding the resort. They can, instead, rely on treated wastewater for this function.
The treated wastewater is stored in two large reservoirs during the winter months and is then reused for irrigation when summer arrives. To further conserve the water, the inn hydrates its surrounding plants and trees mainly with drip irrigation. This uses far less water than does more traditional spray irrigation.
 |
Photo: The PlumpJack Group |
| The inn’s efficient heating system includes
galvanized sheet metal roofs. |
The inn’s recycled water also stocks the fire hydrants and fire sprinkler systems at the resort’s common areas. In the future, excess recycled water from The Carneros Inn’s storage ponds will be sent to the neighboring Perez & Sons Vineyard for drip irrigation of about 6.5 acres of vineyard there. However, this has not yet happened because the vineyard currently lies fallow, as its owners seek to replenish the quality of its soil, which has been used heavily, before growing new grapevines.
“Using the recycled water is truly an important part of our water treatment plans,” Philbin says. “We have a cap on groundwater extraction here. It’s critical, then, that we reuse our water as much as we possibly can. Getting two uses out of it, then, is very important.”
By using its treated wastewater for recycling, The Carneros Inn is able to boast lush landscaping, something that boosts the inn’s popularity and, of course, its profits.
“We do not have nearly enough domestic water to properly irrigate our land and all the landscaping that surrounds the inn,” Philbin says. “We need to make use of the recycled wastewater just to continue to offer the landscaping we have. We have acres of lawns here. Using recycled wastewater allows us to have these features. That’s what sets us apart.”
The wastewater treatment plant that makes all this possible has a number of interesting features. The plant’s phase-one system consists of a self-cleaning fine screen at its headworks, a micro-filtration membrane bioreactor, a chlorine contact pipeline, a permeate pump station, and standby auxiliary power that operates the recycled water system during power interruptions.
The plant’s first phase also boasts an equalization/emergency storage facility; chlorine residual sampling station; recycled water seasonal storage pond; recycled water pump station; and spray, drip, and subsurface irrigation systems.
The facility’s phase-two additions include new equalization/emergency storage and pumping facilities, two additional membrane filter modules, upsized permeate pumps, an additional phase-two recycled water seasonal storage pond, storage pond transfer pumping facilities, and recycled water facilities for the inn’s phase-two expansion landscape irrigation and fire-protection systems.
The facility is a membrane bioreactor plant, says Frank Chua, senior project manager with HydroScience Engineers, the company—with offices in Sacramento, Stockton, and Napa, CA—that designed The Carneros Inn wastewater plant. This type of plant is an especially efficient variety, Chua says.
The plant relies on membranes to filter the wastewater it treats. After the water goes through the oxidation process, filters handle its secondary treatment. These filters eliminate the need for clarifiers while still producing high-quality water, Chua says.
The plant then transfers the treated wastewater to one of two onsite seasonal storage ponds, where the water remains throughout the winter. Once the weather breaks, inn staffers can use the water to irrigate the landscaping surrounding the resort.
Conserving a Prized Resource
Chua says he’s happy to work on projects like the treatment plant at The Carneros Inn. The onsite plant shows that even high-traffic businesses such as resorts can conserve water, he says.
 |
Photo: The PlumpJack Group |
| The inn’s recent expansion required the treatment system to upgrade from handling
30,000 gallons of water per day to up to a possible limit of 80,000 gallons per day. |
“It’s a very good use of the water,” Chua says. “It’s especially important here in California, with water recycling being a major topic these days. I’m just happy to be part of a project where the client has really taken a proactive approach in doing the due diligence, where the client has committed to taking care of the environment and reusing as much of the water as it can.”
This attention to the environment is not a major surprise. Keith Rogal, founder and chief executive officer of The Carneros Inn, is an ardent environmentalist and has taken several steps—not just with the resort’s wastewater treatment plant—to ensure that the inn does not have a negative impact on its surroundings.
Rogal, for instance, made sure that construction crews relocated rather than simply cut down several old oak trees on the property when it became impossible to build around them in their former locations. In addition to its water conservation system, The Carneros Inn features a ground-source heat-pump system rather than traditional air conditioning to heat and cool the resort’s individual cottages and buildings, according to information provided by the resort.
A ground-source heat pump is far more efficient than are traditional air-conditioning systems, relying on the temperature deep under the ground to heat and cool. In the summer, the cool temperatures from the ground act like a heat sink, absorbing heat from inside the buildings. During the winter months, the earth acts as a heat source providing a baseline heat of 65 degrees that radiators can use.
Rogal’s attention to the environment is even present in the style of roofs at the inn. According to the inn’s publicity department, the resort’s roofs are made of galvanized sheet metal, which reflects the heat and reduces cooling loads. Unlike composite shingles, the material can be recycled later.
Balancing the Water Surplus
When plans for the treatment plant’s expansion first came up, resort officials and engineers at HydroScience faced a challenge: What would they do with the additional water that was going to be generated onsite?
How would the resort dispose of this surplus water?
The solution? Create a water balance, with the goal of reusing as much of the water as possible onsite. The plan called for engineers to develop an onsite storage system where the treated wastewater would remain during the winter months. Resort officials could then tap into this seasonal supply in the warmer months for irrigation and rely on some of it permanently for fire protection.
In the future, when the neighboring vineyard resumes growing its grapevines, the inn will send treated wastewater to its fields, too. The inn’s two onsite storage ponds each hold about 8.6 acre-feet of water, says Chua. The first seasonal storage pond, which was built for the first phase of the wastewater treatment plant, is an earth-lined pond. The second pond, though, built for the phase-two expansion, is lined with a high-density polyethylene liner.
The plant has another unusual feature. It is housed within a 5,000-square-foot barn on the resort’s grounds. The same barn also houses the resort’s hot-water generators and maintenance shop. No one driving by, though, would confuse the barn with a typical storage shed or municipal plant. This barn was designed to fit in with the overall architecture throughout the resort.
“You’d never be able to tell that building is a water treatment plant,” Chua says. “You drive up and you think it’s part of the spa facilities. Then you go inside and see that it’s a water treatment plant. It’s located right next to all these high-dollar homes. It’s designed to fit right in. Every time I drive up there, I’m amazed.”
The plant is also extremely quiet. This is by design. The people inside those high-priced homes certainly don’t want to hear the grinding and sloshing of a wastewater treatment plant.
The barn that houses it isn’t the only reason for the treatment plant’s silence. The plant features two equalization basins that collect the raw sewage as it enters the facility. Plant crews can then pump water as needed into either of the basins—which, combined, can store 40,000 gallons of water—without resorting to short cycling and the noise that often generates.
“We can control the grinder pumps that way,” Philbin says. “We can keep the plant running at a low level throughout the day, 24 hours a day, rather than going through all that short cycling. The equalization basins are very helpful that way.”
So far, the relationship between the community and the inn has been a positive one, Philbin says. Napa Valley residents appreciate the fact that The Carneros Inn respects its environment.
Philbin says the resort’s wastewater treatment plant, and the reaction to it by neighbors, is a prime example of this.
“The fact that we have not gotten any complaints about this facility is a testament to the lack of noise and odor that it produces,” Philbin says. “We have had no complaints, none whatsoever. For the most part, people driving along the highway don’t even realize that it’s a wastewater treatment plant. It’s such an architecturally pleasing building. It is not a nuisance in any way.”
Dan Rafter is a technical writer based in Illinois.
OW - July/August 2007 |
