At the Feb. 20 meeting of the Osceola City Council, the council approved 4-0 entering an agreement with Petrotek Corporation for a Deep Injection Well Feasibility Study. Councilwoman Sonya Hicks was absent.
The study is being conducted as part of the city’s ongoing efforts toward a recirculation project that would recirculate effluent from the wastewater treatment plant back into the West Lake watershed, to provide some additional water.
Study
Osceola City Administrator Ty Wheeler explained to council the proposal from Petrotek will be split up into two tasks - Task A is an eight-week study with a cost of $38,000 and Task B is an additional four-weeks for $24,000. The costs are eligible for the state’s planning and design loan that the council has already taken action. The first part will look at the geology and history of the area, while the second part will cost out the wells and provide recommendations.
Mark Seip with Veenstra & Kimm spoke to the council about Petrotek, explaining that all they do is wells, and will bring in well drillers, who they will supervise throughout the drilling process.
Siep spoke of how Petrotek will examine for “fatal flaws” during drilling, which in simple terms, is where the material injected into the ground finds another way to come back up, requiring more work to plug additional holes. An example given was a well that was drilled about 5,000 feet down in Colorado to inject toxic material, only to find it could come back up in other abandoned wells. All of those wells had to then be found and plugged, which added more time and cost. Seip didn’t perceive this to be a problem here, as the well will likely be at least a mile down, and under the Jordan Aquifer.
After Petrotek is done with their study, a permit will be required by the Iowa DNR to drill the well, though Seip speculates that DNR will refer the project to the EPA Region 7.
Well sizes, costs
There are two different sizes of wells that Petrotek prefers to do - a 10-inch or an 8-inch. Along with a price difference, there are lifespans to both, with the larger one having 50-60 years before needing to be relined. The wells consist of steel pipes with a mortar lining, and a bigger well may have room for two pipes. The chloride waste will be discharged down a 27/8-inch tubing, where it goes into the earth into a confined area. According to Seip, Petrotek advised that it is better to constantly feed the well as opposed to turning it off and on. Details such as horsepower and pressure needed are to be determined. The injection well will be at the new wastewater treatment plant, possibly in its own building.
To drill a well a mile down, the estimated cost is between $2-4 million. The depth of the well will also affect the horsepower needed for pumping.
Project recap
The effluent recirculation has been proposed to be used on a periodic basis to help bring water levels back up in West Lake, Osceola’s only water source. Last fall, it was estimated that four months of recirculation would see an estimated 43 to 69 million gallons provided, with eight months at 178-276 million gallons, or about 600-800,000 gallons per day. Data has also suggested that the water that would be recirculated into West Lake would be even better than the current water, as the effluent would be void of nutrients. The last quoted project cost was about $16.5-million, and it would take about two years from start to finish. An injection well would be a separate project cost.
Some additional work will have to be done with the recirculation project, including running a pipeline from the wastewater treatment plant to a secondary outfall at a southern finger of West Lake, south of Ivy Street, as well as some modifications done at the treatment plan to include additional filters to treat the effluent. To treat the effluent, the proposal is that it will go through tertiary treatment steps before going back into West Lake. Part of that treatment would include a reverse osmosis system and the waste stream, or reject, would have a high concentration of chloride waste. What is rejected would be cleaned again to concentrate it more before going into the well.