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additional water table elevation data points. Figure 6, Groundwater Conditions, illustrates <br /> well locations and the elevation of the surface of the water table across the Site. <br /> Groundwater Monitoring: Groundwater monitoring is currently conducted at the Site on an <br /> annual basis. Annual monitoring for diesel range organics (DRO) of the potable well that <br /> supplies the quality maintenance building (QM Lab) is conducted as a condition of the <br /> current permit. The monitoring results are submitted to the City on an annual basis At the <br /> time the monitoring requirement was established, the potable well that supplies the quality <br /> maintenance building (QM Lab) was the only on-site well available to be tested. Since that <br /> time, the Elk River Landfill installed monitoring wells associated with the groundwater study <br /> they conducted during environmental review of their proposed landfill expansion. Tiller is <br /> proposing to replace annual monitoring of the QM well with annual monitoring of one of <br /> the Elk River Landfill monitoring wells. Well 319 OWA is located a few hundred feet from <br /> the QM well. The QM well that has been monitored in the past is a production well, with <br /> the screen set well below the water table. Well 319 OWA has been completed so that the <br /> screen intersects the water table in unconfined conditions and therefore is a preferable <br /> monitoring well for detection of DRO. <br /> Elimination of Industrial Wastewater Discharges: The asphalt plant is currently equipped <br /> with a baghouse to reduce air emissions as opposed to a wet scrubber system. This <br /> eliminates the production of industrial wastewater associated with the asphalt plant. <br /> Equipment Maintenance: Limited equipment maintenance is performed on-site and follows <br /> company spill prevention policies. A service truck comes to the Site to perform routine <br /> maintenance. All used lubricating oil is collected by facility personnel and hauled off-site to <br /> a central collection point (waste oil is not classified as hazardous waste). The service truck <br /> carries a spill containment kit. <br /> Storage Tanks: All fuel and used oil storage tanks over 1,100 gallons(or 500 gallons if within <br /> 500 feet of a surface water) located on site are above ground tanks and have secondary <br /> containment designed in accordance with MN Rules, Chapters 7001 and 7151. Secondary <br /> containment consists of an impermeable concrete enclosure with a concrete base. The <br /> portion of the containment area with the used oil and fuel tanks also has an impermeable <br /> membrane on top of the concrete. In the event of a tank failure the secondary containment <br /> prevents the release of petroleum products to the environment. <br /> The tanks are registered with the Minnesota Pollution Control Agency (MPCA). They are <br /> labeled, equipped with corrosion and overfill protection, and are visually monitored for <br /> leaks and inspected on a weekly basis. At least one person is always present during <br /> unloading and loading of a tank. Due to the high viscosity of asphalt cement (AC),the MPCA <br /> does not require registration of AC tanks. AC tanks are also exempt from certain other <br /> above ground storage tanks requirements; however,secondary containment of the AC tanks <br /> is required and provided at the Site. <br /> Topping off., Company policy does not allow topping off of any tank during transfer <br /> operations. All transport piping is above ground and tanks are equipped with audible <br /> electronic alarms to prevent over filling. Warning signs and chock blocks are used to <br /> prevent premature vehicle departure. <br /> Page 16 <br />