Tacoma Public Utilities and its water-related operations are part of an effort to promote sustainability and environmental quality as a catalyst for economic growth.
Clean-water plants and clean-water professionals contribute strongly to environmental quality. But it’s not often they are front and center in a community’s effort to market itself, promote sustainability and encourage economic growth.
The Tacoma (Wash.) Environmental Services Department, which encompasses wastewater, surface water and solid waste management, is part of just such an effort. A partnership involving the city’s utilities, the Port of Tacoma, the University of Washington Tacoma and its Center for Urban Waters, Washington State University, and the Economic Development Board for Tacoma-Pierce County are working together to establish Tacoma as a laboratory for sustainability and environmental research, and as a hub for businesses involved in clean-water technology.
The utilities are involved in a range of initiatives to save energy, recover resources and improve water quality in the Puget Sound. The city is also part of Water Partners of Tacoma, which presents an annual Wellspring Conference focused on water quality, sustainability and clean-water technology (see sidebar).
Representatives of the various entities shared their thoughts on Tacoma’s ventures in an interview with Treatment Plant Operator. Participants were:
- Michael P. Slevin III, P.E., director of the city’s Environmental Services Department
- Jody Bratton, P.E., assistant manager of operations and maintenance with the Environmental Services Department
- Geoffrey M. Smyth, P.E., manager of Environmental Services Department’s Science and Engineering Division
- Dan Thompson, manager of the Environmental Services Department’s Business Operations Division
- Joel Baker, professor and Port of Tacoma Chair in Environmental Science at UW Tacoma, and science director of the Center for Urban Waters
- Bruce Kendall, president and CEO of the Economic Development Board
TPO: What’s the reasoning behind this focus on sustainability and clean water technology?
Kendall: From the Economic Development Board’s perspective, we see clean-water technology as an emerging field that has a huge economic upside. We believe Tacoma has world-class assets that we can leverage to recruit investments and research, and the jobs that go with them, and then market the science and technology that’s developed here to the rest of the world, while doing good things for ourselves and the environment.
Slevin: My focus as environmental services director, and one of our city council’s focuses, is to provide a sustainable, healthy environment for our citizens, and protecting the water quality in the Pacific Northwest is really critical to that. Toward that end, our wastewater treatment plants are outstanding in meeting their NPDES requirements. They have more than 15 years of perfect compliance. Just three years ago we completed a plant facility upgrade costing more than $85 million. We’ve been involved in Superfund clean ups in and around the Puget Sound. We also have a strong focus on marine water quality on our Surface Water [stormwater] side.
TPO: How does Tacoma promote its clean-water attributes?
Kendall: We do this in three ways. First, we use the assets we have in our regular recruitment efforts. A staff member is focused on two of our cluster areas — clean water and aerospace — and works to recruit companies into this market. Second, we market our area to the world through media placements. Even for those not in the clean-water space, it’s worthwhile to know of the innovations occurring in our marketplace. Third, we do internal and external marketing to individuals. We’ve done that so far through the Wellspring Conference. It’s an opportunity to shine a light on the assets we have and invite visitors to share, network and accelerate innovation. The goal is to have this become a place where people from around the world want to be, need to be, if they are working on solutions related to water contamination.
TPO: What is the role of the university, research and education in Tacoma’s quest?
Baker: About 20 years ago, the city and its utilities, along with the Port of Tacoma, were involved in cleaning up and restoring the Thea Foss Waterway, which essentially is the front yard of the city. Around the same time, the University of Washington created its branch campus in Tacoma. Part of the strategy was to say we’re not only cleaning up this area, we’re going to revitalize it. So the Center for Urban Waters was created as partnership between the city, the university and the Puget Sound Partnership, which is the state agency responsible for restoring Puget Sound. Those three organizations sit in the same building on the waterfront and are designed to be catalysts for innovation.
TPO: On the wastewater treatment side, what is being done to advance sustainability?
Slevin: We have three major initiatives. The first is energy efficiency. We’re working with government and local industries to identify projects identified in a high-performance efficiency audit, and we’ve seen significant electrical energy savings in the treatment plants — around 9 percent in the past year, and that is increasing. Second, we’re looking at using biogas. One of our goals is to increase gas production by possibly taking commercial food waste from our solid waste utility directly into our plant. The greater volume of gas would then be scrubbed and used to fuel our garbage trucks. The third initiative is TAGRO, which is Tacoma’s biosolids product. We are constantly trying to grow that brand. It’s a great brand, and Tacomans love it.
TPO: What specific progress has been made on energy savings?
Smyth: About five years ago, consultants identified a laundry list of projects we could undertake to reduce energy consumption at our treatment plants. One thing we did was upgrade the oxygen generation system for our high-purity oxygen secondary treatment process. Our operations and maintenance personnel came up with a plan to alter that process so that less energy would be used in the generation of oxygen. In addition, in 2013 we used less energy during our wet-weather events, lowering our peak usage, and reduced demand charges from our utility.
Bratton: We tried going to one compressor instead of two to provide air for the generators that produce the high-purity oxygen. We tried it, and it worked — we reduced our power usage while still maintaining a happy bug supply to treat the wastewater. So now we produce enough high-purity oxygen using one compressor instead of two. That reduces our peak demand, resulting in monthly savings from our power supply company.
TPO: What else has been accomplished on the energy front?
Bratton: We have an energy team consisting of engineering, operations and maintenance personnel that meets twice a month. We have a register of energy-saving projects at the plant that we’re looking to implement. We’ve looked at putting variable-frequency drives on our pumps and on our aeration blowers. We’re looking at turning off lights and the heat in areas of our buildings that are mostly unoccupied.
Smyth: This past year we shaved $88,000 off our electric bill. On top of that, at the end of the year, we received from Bonneville Power Administration and the city’s power company a second-year energy savings incentive check for about $48,500. That’s compounded savings, and we’re pretty proud of that.
TPO: Where do you stand on the biogas initiative?
Slevin: Last summer the wastewater and solid waste utilities partnered on this project. The solid waste utility had been doing a pilot project with 60 restaurants and other food-related businesses to collect their pre-consumer food waste. They put a pulping machine and a storage tank at the landfill, and we hooked up a system at the wastewater plant to pump that food waste directly into our digester. The trials were successful. The next step is to analyze the data and look at the next phase — whether we want to expand the commercial food waste program and how we would go about doing that. The aim would be to capture the increased amount of gas and feed that to compressed natural gas vehicles for the fleet of trucks used by our utilities. At present we use biogas instead of natural gas for heating the treatment plant buildings and for providing heat for the treatment process. It would actually be more economical to purchase natural gas and either sell our biogas on the open market or offset the purchase of diesel fuel for our vehicle fleet. We are starting to look at using heat exchangers and heat pump technology to capture energy from our effluent to heat the plant. If we take in more food waste and increase gas production, ultimately we’re going to have more solids and more TAGRO on the back end. We’ve been working across multiple divisions in our organization — science and engineering, plant operations, solid waste — to figure out the best way to do these things.
TPO: What innovations are in store for the TAGRO program?
Slevin: Here again we’re combining efforts with our solid waste group. They collect yard waste that is composted and sold by a private party. We may want to recapture some of that stream and sell it as a Tacoma compost. TAGRO would manage it.
Thompson: We’re also trying to put together a commercial topsoil mix to add to the product line.
TPO: So far, what innovations have come from the partnership with the university?
Baker: We’re trying to create new rain garden designs for stormwater control that would use the TAGRO product. That research is being done at the University of Washington in cooperation with the city. We’re also working with the drinking water utility, which is building a $200 million water filtration plant that will generate residuals as part of the flocculation process. We think that material, which at present is a waste that has a fairly high disposal cost, can be engineered into a material that can be used in rain gardens to help remove nutrients from stormwater. That work is underway in my lab right now.
TPO: What is the city doing on the stormwater front to limit contamination of Puget Sound from runoff?
Slevin: There are three pieces of the puzzle. One is illicit discharge reduction. We have inspectors, and we offer classes to help people be better stewards of the environment and not pollute the stormwater to start with. The second piece is maintenance, which includes cleaning stormwater pipes and sweeping streets to keep fines and contaminants from entering the system. We’ve found that extensive maintenance of stormwater systems to remove legacy pollutants gives by far the biggest bang for the buck in surface water quality. We had cleaned catch basins, but we had never actually gone through and scrubbed the pipes. We went up the drainages, steam-cleaned the pipes and tested before and after, and we saw an increase in water quality, reductions in PAHs and reductions in metals that were astronomical. The third phase is treatment, which is the most expensive but for some areas is the only solution. We work our way up the cost chain from training, education and inspection, to additional maintenance, and finally civil engineering solutions.
TPO: What kinds of treatment have been deployed for stormwater?
Smyth: Our NPDES permit requires us to enforce treament for development and redevelopment projects. We have more than 25 rain gardens in various locations. We have the largest canister system in the state, with more than 250 canister filters in an area of 51 acres. We’re looking at putting in more canister systems in the downtown area. We also have a lot of silvicells. In addition, we’re working on partnerships with private developers on low-impact development, including complete streets that have water-quality elements built in and reduce runoff output. We are also a leader in the world for green roads, which include pervious pavement instead of concrete. We have four certified Greenroads, the most of any city in the world.