Beans, Beans, the Magical Fruit: AGP Stinks Up Aberdeen with Hydrogen Sulfide

Must every dollar of South Dakota’s corporate welfare dollars go to stinking up the state? Our dogged subsidization of CAFOs has obvious odorous impacts; now it turns out Aberdeen’s new soybean processor AGP is turning its state subsidy into dangerous and illegal levels of fart gas.

The Aberdeen City Council held a special meeting Wednesday to address excessive levels of hydrogen sulfide in the city sewer system on the east side of town.

Midstates Printing, which is downstream from the sewer discharge point from AGP on the east edge of Aberdeen, reported strong odors on several mornings starting in July 2019, after AGP began operating. City water reclamation officials quickly found that AGP was discharging water with biochemical oxygen demand (BOD) exceeding the limits set by its agreement with the city under the Federal Clean Water Act. The daily maximum BOD under the agreement is 275 mg/L; AGP’s average BOD from July 2019 through December 2019 averaged 504 mg/L.

AGP says it doesn’t know which of the chemicals it dumps into our sewer is causing the problem, but the result is hydrogen sulfide gas that businesses (and AGP is in an area, so at least we’re not stinking up a residential neighborhood… although there is a daycare near Manhole #4, about a third of a mile south) downstream—or downpipe—can smell emanating from the wastewater system. Aberdeen wastewater reclamation level chief Peggi Badten said monitors placed in manholes downpipe from AGP last month confirmed that the wastewater contains dangerously high levels of hydrogen sulfide—and she pointed out that the monitors were placed at the top of the manhole, and hydrogen sulfide is a heavy gas, so the readings would have come back hotter deeper in the pipes.

Badten said hydrogen sulfide can be lethal and explosive; city engineer Robin Bobzien explained that hydrogen sulfide can turn into acid that will erode the concrete and metal in the sewer system. As the map below shows, that sewer line runs south to Highway 12, then west to the mall and Sanford hospital

City attorney Ron Wager asked the utility officials whether they were sure the source of this pollution is AGP. Bobzien said no such odors were reported in the area before AGP began production; the amount of wastewater AGP is now generating exceeds the load of all the other users on that line combined.

The city issued AGP a compliance order on February 18 requiring that, in 30 days, the company notify the city of its plans to fix the problem and, in 60 days, submit construction plans for facilities to remove the excess BOD. The city also required AGP to lower the temperature of its wastewater by the end of February, since higher temperatures increase the growth of the BOD. Wastewater enters the sewer at the AGP plant at temperatures of 90°F to 100°F.

Wager showed video taken Tuesday comparing concrete quality in a manhole a quarter mile west of the AGP line with the concrete in a manhole on the AGP line. The manholes are the same age, but the manhole downline from AGP shows white residue and soft spots that indicate damage from hydrogen sulfide. Watch at 19:30 in the meeting video:

Bobzien reported similar symptoms of hydrogen sulfide corrosion on the sewer system at other access points downline.

Wager said AGP’s cooperation so far suggests that hard administrative responses are not required yet, although he noted that the city has the power to issue a cease-and-desist order that would shut down the polluting activities entirely.

Kelly Jorgensen, AGP director of environmental compliance, apparently came up from AGP HQ in Omaha to lead a four-man company delegation to address the council. Jorgensen said the higher BOD discharge is as much a surprise and mystery to the company as to the city. He said the wastewater contains suspended solids, oil, and ammonia from the processed soybeans. AGP has looked at its machinery, operations, and the soybeans themselves. They can’t find any clear difference between the machinery and operations in Aberdeen and their other factories; they mentioned that this is their first plant using South Dakota soybeans.

Hmmm… so could South Dakota soybeans be more magical than those of other states?

Jorgenson says AGP and its consultants are looking at various options to lower the hydrogen sulfide levels, but they are concerned that some mitigation options only move the generation of hydrogen sulfide further downpipe. They recommend adding an oxidizer like hydrogen peroxide to prevent the system from going anaerobic and generating the stinky gas. AGP could also try adding sodium nitrate, but the proper dosing to resolve the problem is unknown. Jorgensen said the current plans are short-term fixes; AGP is still trying to figure out what sustainable long-term changes it can make to its operations.

Jorgenson suggested the city powerwash the sewer lines to remove some of the microbes that produce hydrogen sulfide. AGP offered to help, but the city said it would send its crew in to perform that work. Jorgensen assured the council that AGP is keenly interested in increasing transparency and cooperation in both directions and working to resolve the problem. He said that if users downpipe are noticing odors, the city should check their plumbing, as properly flooded pea traps should not allow gases to enter from the wastewater system. Bobzien noted that Midstates checked its traps right away when it noticed the odors and found no plumbing problems.

Councilman Rob Ronayne asked AGP if they are acknowledging that they are the cause of the hydrogen sulfide levels. “We are the contributor,” Jorgensen said, although he also noted that Aberdeen’s flat, lift-station-dependent wastewater system is more susceptible to microbe and hydrogen sulfide build-up than gravity-flow systems.

Anarcho-capitalist Mayor Travis Schaunaman repeatedly thanked AGP’s officials “for having made the trip up here today and representing the company” and acknowledged the “massive inconvenience of putting that many miles on the road” and said that AGP had “done a great job of qualming everybody’s concerns.” Evidently wanting more “qualming”, other council members asked for weekly updates and in-person reports from AGP officials every other week.