A complicated way of doing a simple thing
A “Rube Goldberg” machine is an impossibly complicated device that does a simple task. Rube himself was an engineer, who celebrated the spirit of invention with his cartoons. There was always some implausible step that guaranteed failure in the real world.
While this machine is indeed complex--it sometimes works. And it was conceived with the best intentions--to safeguard the environment and the public water supply.
In 1990s, as the University expanded to the west, there arose a need for centralized heating and cooling for the new buildings. Because this would be more efficient if combined with electrical generation, plans for a new power plant were laid.
Although this expansion had long been planned, suddenly the power plant was put on fast track. Built by MG&E on the west side of the UW Campus, it is now known as the Cogen facility, because it combines power production with heating and cooling.
The University and MG&E built the power plant together. All of us use the groundwater reservoir for drinking and cooling and industry. The Madison Metropolitan Sewerage district processes the wastewater and sends it out of the watershed, mostly into Badfish Creek. Madison's Water Utililty has an interest in keeping groundwater pure and plentiful. So many stakeholders are involved--that’s partly why this project grew to Rube Goldberg proportions.
Saving the groundwater
- A system to inject treated sewage water into the ground
- Settling ponds
Because the project was on fast track, they couldn’t dilly-dally with unproven solutions like rain gardens, which take a lot of coordination with the public. There wasn’t time to seriously consider treated water from the sewage plant. The amount of land needed for large settling basins wasn‘t available.
That left the alternative of a mechanical system to inject stormwater into the subsoil. Now they had to find a location. The groundwater is a big reservoir--so it didn’t matter where the stormwater was injected--they just had to find a large supply of storm water and some unused land--with sandy soil--where the water could be injected.
The recharge area is the brown triangle at the center.)
When the golf course was built, they drained marshy soil by building a stormwater pipe leading towards Lake Wingra. Any dirty storm water dumping into Odana Pond now had a direct route to Lake Wingra. The load of phosphorus and sediment to the lake now increased.
But the MG&E plan called for taking water from Odana Pond and injecting it into the sand. Stormwater would would now flow through the ground, filtered all the way--dirty storm water converted to crystalline spring water.* This could help clean up Lake Wingra.
The Friends group had a number of experts in water resources on the board and among their advisers. Their approval helped in getting the whole plan to inject water approved. Now construction of the Cogen plant could proceed.
So a second key permit was written by DNR for discharging stormwater into the ground. This permit states that certain levels of contaminants like salt in the test wells around the site cannot be exceeded.
But MG&E was going to be pumping a lot of water, and they weren’t positive how much water the soil would accept. They were worried that even washed gravel would still have some residual rock dust that would clog up pores in the soil. So they decided instead to use plastic pellets, like the ones used in shipping boxes. The manufacturer did tests, to make sure the plastic pellets wouldn’t be squashed by the weight of the soil.
The water coming to Odana Pond--like most storm water--is dirty.
Main tributary to Odana Pond emerges from under Beltline. 4/1/11.
Pumping into the ground is limited by two things…
- The amount of water the soil will accept.
For whatever reason, the project is having trouble pumping enough water into the ground. You can see the decline in the graph of daily volume below.
Pumping cannot occur if the Pond falls below a certain level--to protect pond life.
The first permit requires they eventually reach 80.4 mgy, but they are only pumping about 60 mgy now. And that’s with pumping all the time. Those last three words are important…
Salt contamination in the groundwater
Early this winter, Jim Lorman was burning the night oil, checking some data from Lake Wingra. He’s on the faculty at Edgewood College, and a founding member of the Friends of Lake Wingra.
But more disturbing, he noticed that salt levels (measured as chloride) at two test wells, at some distance from the injection site, had exceeded the DNR's Enforcement Standard of 250 milligrams per liter (mg/l). In fact, one well had exceeded the Preventative Action Limit from the very beginning, in May of 2006.
- The Enforcement Standard (ES). This is the level not to be exceeded. More.
Once groundwater is contaminated, it means all the springs and streams are saltier to begin with, making aquatic life more vulnerable to the “flush” of road salt that comes at first thaw.
For three years, the groundwater near the injection field had reached contaminated levels in the spring, and neither MG&E, nor the permit guardians at DNR, had said anything to Jim. Nitrates and arsenic were also briefly spiking above PAL levels, though less consistently.
Fixing the problem
DNR has the power to require MG&E to meet their permit obligations, but they can’t dictate exactly how MG&E meets the obligations. Early in 2011, MG&E sent a draft plan (dated Jan. 21) to DNR, for how they would deal with the problem of contamination of groundwater:
- Monitor salt levels of water in the intake pipe.
- Stop pumping whenever the salt levels reach the protective action limit of 125 mg/l.
- But, pump for a minimum of an hour each day (regardless of salt levels, and even if over the PAL). This pumping of an hour every day, when pond water is salty, is presumably to help keep the pores in the soil open.
- Once in the groundwater, the salt will be there for decades. There’s no way to remove it.
- The PAL is the level at which you take preventative action, not the OK level to pump--especially when you are pumping extremely large volumes.
- Pumping for an hour a day, no mater how contaminated, is simply a violation of regulations
- The plan does nothing to solve the root cause of the problem, which is spreading too much road salt.
Everyone agrees--the Friends, MG&E, and DNR--that overuse of salt on the West Side is the root cause of the problem. West Towne photo, 3/14/11.
Onwards… towards 80 million gallons a year
And--looming in the background--is the question of pumping enough water to meet the second permit--the 80.4 mgy. To reach that, MG&E will have to revisit all alternative methods to get water into the ground, including a large rain garden program in the neighborhood.
A waste of energy and water
The Odana project's basic goal is water conservation. It's a deal to prevent harmful effects to the lower Yahara River by swapping water. But the project does nothing to replace the 76 mgy*** lost from the basin as vapor. The project accepts the idea that there will be less water overall in the Yahara. It just tries to prevent very low flows by "borrowing" water from the ground during droughts. That's OK.
There are three tools available to fix the problem--to use singly or in combination:
- Create programs to reduce use of salt in the Odana basin.
- Create new infiltration areas or projects (including rain gardens) that infiltrate water from neighborhoods with less salt.
- Pump water at the Odana project only when salt levels in the pond are below the PAL.
MG&E, and the people at DNR who negotiated the "swap agreement" deserve a lot of credit. They were exploring new ways to allow development in Madison, and at the same time protect the environment. The Odana facility looked good on paper, but in the real world, it's not performing as hoped. The time has come for hard choices. Some of the remedial actions may still allow the Odana facility to continue operating.
They are going to have to build more infiltration--to reach their required goals. It's time to get back to the rain garden idea.
*** mgy=million gallons per year. This figure of 76 mgy is for the Cogen plant. The Charter Street heating plant sends a staggering 137 mgy out of the basin, and the Walnut Street plant sends 75.5 mgy out of basin. These two older plants are covered by the license, but the Odana mitigation figures compensate just for Cogen, because the water used by the older plants was "grandfathered" into the agreement.
Request for Building Commission action on Cogeneration
Study of harmful effects of salt on key aquatic species.
Risk study of salt in Australia
This powerpoint presentation by Steve Gaffield, May 11, 2011, presents data and photos about the Odana Project.