What was the purpose of the Water & Resource Recovery Center upgrade?The main reason for the upgrade was plant age. The majority of the plant was built in the 1960's and 1970's. There was a relatively minor upgrade in the 1990's with no capacity increase. Much of the equipment was operating well beyond its normal design life and major treatment processes were at the end of the intended life. Additionally, there were some capacity issues.
What was the cost of the upgrade?
Approximately $64 million.
What is the impact to my water bill?
Sewer rates in the City of Dubuque have traditionally been some of the lowest in the state, as compared to other larger Iowa cities. Dubuque’s average household rate in 2018 is $39.25 per month. Although Dubuque has one of the newest wastewater treatment facilities in the state, the average monthly rate for the other 11 cities in Iowa with populations over 50,000 is $37.13, just five percent below Dubuque’s rate. Davenport, Des Moines, and Ankeny have higher rates with Ankeny’s rate at $67.52 per month, 72 percent higher than Dubuque’s rate.
What benefits did the upgrade provide?
The benefits include reduced operating costs, replacing outdated equipment and improving reliability, environmental awareness, and enhancing Dubuque’s "Green City” image. The project also qualified for low-interest financing which will establish a road-map for 20 years and beyond.
How does the upgraded facility differ from the original facility?The original facility involved incineration of bio-solids (sludge), and disposal, by landfill, of the remaining ash. The upgraded plant uses anaerobic digestion to break down the accumulated bio-solids. Anaerobic digestion uses bacteria, in the absence of oxygen, to break down bio-solids. The digested solids are applied to farm fields as a soil conditioner. During the digestion process, methane is produced and collected. The methane is used to heat the digesters, and generate electricity for plant operations. The past disinfection process (before final discharge) used chlorine, which is a danger to workers and the environment. The disinfection system is ultraviolet disinfection, which uses UV rays to inactivate remaining microbes.
What are some of the benefits of using anaerobic digestion?
The anaerobic digestion process allows us to produce methane, clean it up, and use as a fuel (has same properties as Natural Gas). The methane used in co-generation, powering microturbines, which generates electricity, and produces heat, is used to heat the digesters to the required temperature.
How does anaerobic digestion compare in terms of operating costs?
Upfront costs for anaerobic digestion are more expensive, but yearly operating and maintenance costs are lower (generating our own electricity and much of our own heat). Also, bio-solids can be used instead of discarded as waste.
What is the expected life of the upgraded plant?
The upgraded plant is expected to operate for 35 - 40+ years. These improvements will lead to a more stable rate structure for decades to come.
How was this $64 million upgrade funded?
The project was initially funded with the state revolving fund. The federal government gives money to the state, which is loaned to municipalities at low interest. Money is repaid to the fund, then used on other projects. The user's fee - pay for what you use. Rates for homeowners are very competitive with other cities in Iowa (rates are near the bottom). Rates will rise more towards the middle, but as other communities embark on projects, their rates will rise as well.