Madison a go for H2O
Indian Creek Water Reclamation Facility
by Tara Derock Mahoney
photos by Angelina Bellebuono
It isn't often that city residents get to see exactly what $8.5 million can buy, but Madisonians who take the trouble to drive by the city's new water reclamation facility (WRF) on Indian Creek Road can do just that.
The one million gallon per day wastewater treatment plant is nearly complete and expected to come online within the next 60-90 days.
“They're pulling wires, getting energy to everything right now,” said Bill Smith, the Jordan Jones & Goulding project engineer who is overseeing the work of Southern Champion Construction for the city. “In a couple of weeks, they'll begin testing [wastewater treatment] equipment.”
When it comes online, the new, state-of-the-art “Indian Creek Water Reclamation Facility”--as it has been formally named—will draw about 250,000 gallons per day (gpd) of gravity-fed wastewater through its sequencing batch reactors (SBRs), and release re-use quality water back into Four Mile Branch, the adjacent stream. Currently, the wastewater that will come to the Indian Creek facility is treated at the city's “Southside” treatment plant off East Avenue in Madison, pushing that 660,000 gpd facility toward 80 percent capacity.
The new WRF, situated on 12 acres, will have a day-to-day capacity of one million gallons of wastewater, capable of handling nearly double that in peak periods. Although the WRF on Indian Creek Road is designed so that three additional SBRs can be built on-site, making the eventual build-out capacity of the new WRF four million gallons per day, city officials hope that they won't see that kind of build out anytime soon.
“This is about all the WRF I'd like to see right now,” said city manager David Nunn. “When the daily load on this site gets to be in the 700,000 gpd range, the city will have to start looking at expanding the plant.”
That number is development-driven, and is likely years away. For now, the new plant will relieve pressure on the Southside plant and improve treatment of wastewater in the I-20 and Hwy. 441 development corridors of Madison.
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The first spadefuls of dirt were turned at the new WRF site in October of 2006, and work has progressed at a steady pace since then, staying fairly true to the 15-18-month projected building timeline. While work on the WRF has gone smoothly, the same could not be said for the construction of the related pipeline that will bring the gravity-fed wastewater (sanitary sewer water only—stormwater is part of another city system) to the plant. That project, involving a bore under I-20, nearly doubled in cost—to more than $2 million—when the drillers hit rock under the interstate. Still, the pipeline is now complete, and the 24-inch wastewater main under the highway is sized such that it is unlikely another bore will be necessary in the lifetime of anyone reading this article. The pipeline begins at the lift station that currently pumps wastewater from the north side of I-20 to the Southside plant; it ends at the gates of the new WRF on the south side of I-20.
Because the new plant will release treated water into a relatively small creek, the quality of that released water, called the effluent, must be excellent.
“The standards for this [Indian Creek WRF] are terribly high,” said Nunn, in an interview at the site last Monday. “We accepted those limits when we asked the state EPD if we could locate here, releasing the effluent into Four-Mile [Branch].”
The water treated by the WRF is monitored by the state Environmental Protection Division for acceptable levels of dissolved oxygen, total suspended solids or TSS, biological oxygen demand or BOD, Ph levels, and other standards. Several sampling sites are incorporated into the WRF, and an on-site lab and a full-time, city-employed lab technician will also be on hand to monitor water quality.
The released water treated by the WRF will be rated by the state as “re-use quality” water, which is just a step below water of drinking quality. In fact, the new plant will not use any potable city water in its operations; a series of pumps will recycle some of the water treated at the plant for use in its cleaning and screening processes.
“We're trying to adapt some of these re-use systems, in a smaller way, for our other wastewater plants,” said Nunn. “Wastewater treatment plants are large users of water.”
Clean water is just one of the elements used to treat the wastewater at the new plant. Waste entering the plant first goes through a series of large screens that filter out the largest pieces of foreign matter.
“I tell the fourth-graders that come to the wastewater treatment plants on field trips that this is where the Barbie dolls and the army men that get flushed down the toilet are screened out,” jokes Nunn. In the new plant, the filtered waste then enters one of the sequencing batch reactors (the WRF has two, which will receive batches of water sequentially under normal operations) and the cleansing bacteria and aerators then go to work, moving through a cycle that lasts about five-and-a-half hours, according to Smith.
“This will be a 24-hour plant,” said Smith. “These SBRs will work constantly, going through about four or five cycles per day.”
In the SBRs, clean, aerated water is siphoned from the upper levels of the chambers, while sludge stays in the bottom. The clean water moves through another set of filters and an ultraviolet light system before it is re-use quality and capable of being released into the stream for readmission to the state's water system.
The new facility will have a monitoring room on premises from which city staff can oversee the production of the plant. Learning the rhythm of any given plant is part art, part science, said Nunn.
“Every plant has its own personality—every plant's sewage is different,” said Nunn. “There are so many things...that you have to balance to keep the effluent at appropriate levels. But this is the place to do it.”