October 6, 2008
On Oct. 1, I attended a public meeting on the Mallard Lake Landfill at the Hanover Park Village Hall. I was expecting less. I expected maybe one EPA officer addressing a small crowd of concerned homeowners, fielding some questions, and then sending everyone home. Instead we had two EPA officers – Steve Faryan and Mike Joyce, plus two or three guys working for the EPA (Steve Ryan and Thomas Kruger among them -- consultants? Kruger looked familiar, but I can’t imagine where I had encountered the man before), Carol Fuller from the Ill. EPA (her name should be recognizable from a lot of IL/EP documents); and in the audience, someone from the DuPage County Health Dept., the Mayor of Hanover Park (Rod Craig), at least one trustee for sure (Wes Eby), and possibly up to two other trustees. So, besides the purpose of assuring homeowners that methane gas would not kill them, the function of this meeting was a political one, to be seen and be seen taking an active role in dealing with the methane leak issue. In all, there were maybe 25 people at the meeting.
We have hundreds of pages of material on the landfill and the leak the EPA has given us, but the story boils down pretty much to this: If you are going to build homes around a landfill, you should have a protective liner – no more than a thick sheet – under the shallow soil you are building on. Carol Fuller said before 1993 (or maybe she said 1991), there was no regulation requiring landfills to have that liner, so Mallard Lake was initially built without any liner. Later, when homes were going to be developed by the south end of the landfill, a liner was finally laid down that would protect those homes. There have been no methane leaks found near the south end of the landfill, thanks to the liner.
Under the landfill is a vacuum chamber that creates a negative pressure. Methane gas is drawn towards a negative pressure, which keeps the methane from spreading – normally. Without the liner, the gas is also to touch the water table when it rises. Methane does not mix with water, so the gas just rests on top of the water table. But, in times of drought, the water table lowers back down, creating a low-pressure opening that the methane gas fills. Later, when the water table goes back up to normal levels, it pushes the methane gas against the soil above it and, because the methane still will not mix with the water (except under great pressure), the methane spreads out over the surface of the water table. Now, it can be virtually anywhere. And while that may sound like a good reason to move to a new neighborhood, the truth is that this diffusion of the gas is a good thing. As long as Volatile Organic Compounds (VOC), like methane gas, found in quantities below health-based screening levels, it does not pose much of a danger. The other thing to be concerned about is how high into the soil the methane gas has seeped. If the gas reaches the shallow soil near the surface, it can poison plants and seep into basements.
Up to this point, while all this sounds very dangerous, there was not much of a problem. Methane gas leaked slowly from the landfill, as it typically does from landfills, and the water table acted as a natural remedy to gas accumulation, diffusing the gas over a wide area. All that changed in October 2007 when BFI, the company maintaining the landfill – powering the vacuum pump under the landfill – suffered a power outage. It was like unlocking all the doors in a prison; lots of methane escaped.
The landfill is dotted with probes that monitor the soil for methane leakage. Soon after the power outage, one probe detected methane in the shallow soil. It was now a situation that required the federal and Illinois EPAs to be called in. Through November, the EPA tested homes in the area. Sub-slab ports were installed under six homes and 224 homes have been monitored with a combination of above-ground detectors and sink-bar tests. The sink bar is a three-foot long metal pipe with sensors at the bottom end that is slammed into all the way into the ground.
No methane was found in people’s homes or detected by the shallow soil tests. However, deeper wells drilled in the residential areas by the north end of the landfill and the portion of the Hawk Hollow Forest Preserve on the east side of Schick Road have turned up methane in the permeable, silty sand that is found 35 to 40 feet down. The clay layer above the sand layer has so far blocked the methane from rising higher. The only living things in danger at that depth are the roots of very old trees. One resident at the meeting complained about the prize tree on his property dying, and of him knowing one other tree that had died since October of last year.
Every time a well led to methane, another well was drilled a block further out to determine how far from the first spot the methane was concentrated. They called this “perimeter monitoring” and it is currently their top priority. As the search widened, it was determined that no gas had leaked as far as the west side of Schick Road, but gas was detected as far north as the vicinity of Greenbrook Elementary School, to which forest preserve land almost touches. No methane was found in the school.
Evidence was found recently of a methane gas fire underground. An underground fire was, the experts there admitted, an uncommon event. The recovery wells in that area were shut down and will not be re-opened until the waste-mass cools. Fuller said the underground temperature at a landfill site needs to stay below 131 degrees Fahrenheit.
The next step is to recover the leaked methane. There are currently five recovery wells, with another seven proposed. One main well, where the most methane has been detected, will have a pipe running gas straight back to the landfill. Since this method requires the most construction, most wells are using mobile compressors – basically 4-cylinder Ford engines running on propane – to pull gas up into the mobile units for later removal back to the landfill. Three will be in Hawk Hollow, three will be in residential areas, and one near the intersection of County Farm Rd. and Schick Rd. Landfill regulations say the clean-up will not be over until it can be proven that no landfill gas is going offsite. Right now, there are six wells where gas readings have gone up. No one has figured out why, though there are some normal explanations for it, such as barometric pressure fluctuations. The EPA wants to run deeper tests to see if any methane is somehow beneath the sand layer.
Steps will be taken to make sure this incident never happens again. BFI has been ordered to have back-up generators to maintain power to the vacuum chamber. This, more contingencies, is the EPA’s second priority. There is no required number of recovery wells the site must have per acreage to return all the lost methane, but however many necessary to prove no methane leak remains will have to be maintained, possibly for up to a year. This will be part of EPA’s “phase two” operation, about four months from now, when they will determine how many wells will be needed for the remainder of the investigation. Wells will then be monitored monthly (one persistent homeowner insisted the wells should be checked in random order, but everyone else agreed that would be a meaningless precaution, as methane gas travels too slowly for activity in one well to push gas towards another.
BFI is upgrading its gas collection system and re-sealing the surface of the landfill and may be made to report annually to the public, or maintain a public web site with updated monitoring data.
EPA has a superfund and has spent $300,000 of it already to oversee the clean-up. At some point, EPA will be in cost recovery mode, though that is a medium- to long-term issue. At that time, they will be looking at the DuPage Forest Preserve’s $100,000 landfill emergency budget.
The Forest Preserve District is checking groundwater separately. BFI has already tested their groundwater. In addition, Nicor Gas has done some of its own soil testing for its customers. This is sort of a “checks and balances” system that keeps everyone honest (one homeowner asked if EPA would hire a third party to monitor them).
A landfill produces methane gas on a bell curve. Mallard Lake has already peaked and is producing less methane now, but still has many years to go until it stops. The BFI permit has a court-ordered 100-year closure period (30 years is typical, though Blackwell’s is 100 years too). BFI can develop the landfill property if they wish as long (as per the rumored ski slope once proposed for the hill), as they have no gas leakage. Their ability to develop the property would be limited by their being completely surrounded by forest preserve land, which cannot be developed.
In the meanwhile, the EPA is willing to write “comfort letters” for homeowners looking to sell their property, assuring potential buyers that the neighborhood is environmentally safe. They are checking private wells one a time, as some owners have complained of gas contamination. However, air in the pressure tanks is a common problem that could appear to be gas contamination in the well, which is why the EPA has to come in and examine the equipment.
By 7:30, the questions were becoming repetitive, but for one and a half hours there was a lot of interesting information. After 8, everyone was invited out into the parking lot to observe a mobile compressor running, to allay fears that they would be too noisy. I did not think they were too loud, but then again, they won’t be on my property.
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