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HomeMy WebLinkAboutSP October 15, 1986 CITY of ANDOVER SPECIAL CITY COUNCIL MEETING-OCTOBER 15, 1986-MINUTES A Special Meeting of the Andover City Council, requested by the SW28 Group, was called to order by Mayor windschitl at 7:40 P.M. , Wednesday, October 15, 1986 at the Andover City Hall, 1685 Cross~own Boulevard NW., Andover, MN. Councilmen Present: Elling, Lachinski, Orttel Councilmen Absent: Knight Also Present: Natalie Haas Steffen, County Commissioner; James Schrantz, City Engineer; Alan Van Norman, Conestoga- Rovers; Bob Hutchison, Anoka County; Collen Herman, County Attorney's Office; representatives of the Pollution Control Agency and the generators. Nancy Misra, PCA - stated that they are in the process of reviewing the report prepared by Conestoga-Rovers. Once they approve the report there will be a public comment period and a public meeting. Alan VanNorman, Conestoqa-Roqers - stated that the report deals with what is physically at the site. There are a large number of exploration wells inside the site, along with some gas probes to push a little of the air out of the soil to find out what's in the soil gas. There are three major soil units on the site, the first being the upper sand unit. With- in this unit is a water table aquifer. The water flows do en here to Coon Creek. Within the upper sand unit is a layer of silt. This acts as a retarding layer for contamination that leaks orf the site. Belm¡ this unit there is some contamination. The next unit down is the till unit. This is finer grain particles. Water cannot pass through it' easily. The lower sand unit gets its water from somewhere else off the site. The pressure in this unit pushes the water up. The gradient determines what the flow will be. The lower sand unit is not contaminated. It's protected by the till unit and the flow is upwards. Water flows from the south side of the site towards Coon Creek. The lower sand aquifer was not contaminated, Red Oaks is not contaminated water from the sand aquifer. They defined minor risks on site. They did not, however, define a health risk. The soil cap over the site consists of using the lime sludge and compacting it as much as possible and using that as the impermeable layer in the system. Above that layer will be a sand lateral drainage system. Above that layer is a clean layer to protect from frost penetration. There's a filter layer between the clean I fill and the sand drainage layer. On the top would be topsoil. Thisicap would prevent infiltration. There would be a grass vegetated cover on top of that. Gas vents would be installed with carbon filters on the tops for volatile gases that might be in the landfill. Mr. VanNorman explained that the ground water extraction system would consist of six perch wells installed in the up~r sand aquifer. They would each pump 10 gallons per minute and would intercept the water before it gets to Coon Creek. The wells would be screened over a very long length. The wells would be similar to a residential well. In the final design, they will determine where to put the pumps. That could be in the till area. The purpose is so that the dirty water is not dragged down into the clean water. The wells are installed in the down gradient Special City Council Meeting October 15, 1986 - Minutes Page 2 side of the aquifer. The wells would be outside of the refuse area. The penetration is only five feet into the till, which itself is about 30 feet. Councilman Lachinski asked where the water would go from the wells. Mr. VanNorman stated that there are three discharge options. Volatile organics are a problem. One way to get rid of them is with an air stripper. The air quality coming out of there is acceptable. The other option for treating the volatile organics is an activated carbon filter. The ground water moves through a pretreated system and then through a pressure carbon contactor and goes into another pressure carbon contactor. The easiest way to dispose of the water is to dump it into Coon Creek, which would require a permit. It would have to be of sufficiently good quality to allow this to discharge into the creek. There are other options to get rid of that water. The water could be allowed to go back into the upper sand aquifer by an infiltration pond. The final option is to discharge to the sanitary sewer. The Waste Control Commission doesn't want clean water in the system however. If the water is too dirty to put in the creek, then the sewer is the best place to put it. A connection could be made to a manhole in Red Oaks. Commissioner Haas Steffen asked if there is any danger because of the gases Mr. VanNorman stated that a permit would have to be issued and the PCA would monitor the process. Ms. Haas Steffen asked if there is a contin- gency plan should the system fail and if there is, would it be implemented immediately. Councilman Elling stated that the city has taken the position that we don't want to use the sanitary sewer system as we would be using up our capacity. It was noted that the carbon filter units are in place in Minnesota and they do work. If the system does fail, you might have to go back and rethink it. Councilman Orttel asked what would happen if the bottom goes out of the pit and you have a rapid release of chemicals. It was noted that there is clay under the pit and at most you would have a slow leakage rate. Councilman Elling asked if there are any provisions for the noise from the air strippers. Councilman Elling asked if there would be a fence around the landfill when it's closed. It was noted that this will probably be a part of the closure procedure. Meeting adjourned at 10:10 P.M. Respectfully submitted, ¡¿.V£ vicki Volk - Acting Secretary