The purpose of this report is to document recent activity and results from the Karst Conduit Program, at Lemon Lane Landfill and to provide information on the next steps. The first enclosure for your reference is a map of the landfill area that includes the locations of all the recent borings. Viacom is continuing to pursue the location of PCB carrying conduits at Lemon Lane Landfill. These efforts are continuing on two parallel paths.

A. Phreatic Investigation

One path is to find the phreatic conduit or conduits that carry the PCBs from the site to the spring. Viacom believes that these conduits are most likely to be found at an elevation of 795 to 800 amsi, but also possibly up to 815 amsi. This is because the wells that penetrate between 795 and 800 feet amsi have water level fluctuations that very closely match the Illinois Central (IC) Spring flows. This zone also appears to be so honeycombed with solutional openings that every well that penetrates this zone encounters at least a small solutional feature. This zone has been shown to be very well interconnected, at least hydraulically. This is proven by the aforementioned water level responses during storms and instantaneous response in distant observation wells during low flow pump tests performed in 1999.

To investigate this zone, Viacom has concentrated on two techniques. First, Viacom has conducted geophysics. Electrical resistivity imaging has been used in an attempt to locate shallow conduits. However, Viacom believes that this technique loses too much sensitivity with depth and may not be appropriate for locating conduits in the phreatic zone. Viacom believes a cross-,hole seismic survey is a more appropriate geophysical technique for this lower zone.

In November 2000, Viacom had Gecoh Exploration performed a single line of resistivity along the southeastern edge of the landfill. The data was taken so that the focus would be on the 785 to 815 horizon. The data is shown in the attached Gecoh report dated 12/3/00. This data was taken to show where areas of high resistivity versus low resistivity were for the placement of boreholes that could be used to perform cross-hole seismic surveys of this lower zone. The cross-hole seismic boreholes would preferably be located in areas of generally higher resistivity. This is because holes in fracture zones may be difficult to keep open and may be much noisier than boreholes in more solid rock.

Based on the resistivity survey Viacom drilled two boreholes. First MW-1 5 on the extreme southeast portion of the landfill was drilled. This location was selected for several reasons:

1. It was close enough to existing well NN-12 (in Valhalla Cemetery) so that a crosshole survey could be done between them.

2. It was over a deep resistivity low that may be a small conduit.

3. It was not in the relatively low resistivity area associated with the Griffin Sinkhole. Thus a borehole in this location along with a companion hole on the northern fringe of the Griffin Sinkhole area would allow a cross hole seismic look across the sinkhole

The boring log for well MW-1 5 is attached. A mud filled conduit was found at an elevation of 803 to 807. A companion borehole 100 feet north of this location was then drilled so that the cross-hole seismic survey could be attempted. This became MW-16 and its boring log is attached. A cross-hole seismic survey was then performed in February 2001 between these holes. The result of the survey is shown in the attached Gecoh report dated 2/24/01. As can be seen, several potential conduits were identified within the 100 feet interval of the survey. These possible conduits seem to correlate with resistivity lows. However, the opinion of Rene Rodriquez, who conducted and interpreted the seismic survey, was that those potential conduits were no larger than anything that had been previously identified or drilled.

Because there are a number of targets identified in the cross hole work, and because the lower zone is so well interconnected, it was decided to see if more water level data, as another technique, could be used as a guide to which portion of the eastern edge of the landfill to focus our efforts. The presupposition that potentiometric troughs indicate the approximate location of main conduits* in karst terranes is discussed in the literature. The best empirical evidence for this was put forth by Quinlan and Ray (1981) in their map "Groundwater Basins in the Mammoth Cave Region, Kentucky". Quinlan outlined 28 spring basins by tracing and showed that major flow, routes coincided with potentiometric lows.

Because this zone is so well interconnected, Viacom believes that the water level in wells that tap this zone will be indicative of the general direction of the conduit flow and may more specifically indicate the conduit locations. To this end, Viacom very carefully resurveyed the location/elevation of many of the wells around the site that penetrate this zone and measured the water levels under low flow conditions over the last couple of months. This data is shown in Table 1. There appears to be a clear direction of flow to the east with the 4 series wells (41 and 4 1 S) being the low spot. To further evaluate the east side of the landfill, a series of wells, spaced at a maximum of 100 feet, which is what we think is the maximum effective range for cross hole work, were placed along the eastern edge of the landfill. The new wells installed were designated MW-17, 18 and 19. Boring logs for these wells are attached.

Since installation of the new boreholes, water level data for the east side boreholes and wells have been taken on two dates. The data is shown in Table 2. Note that there appears to be two lows. One low is associated with the previously identified MW-4 area, and another low centered at MW-16.

Samples for PCB analysis have been taken from each of the new boreholes during drilling. The results of these samples are shown on the boring logs at the interval sampled. Of the 5 new boreholes drilled on the east side, MW-1 8, 19 and 16 have PCB levels in the lower zone that are higher than typical low flow values for the IC Spring. Any conduit carrying PCBs from the site would have to have higher concentration levels than those at the spring, since the spring samples would be diluted with water from the rest of the basin. Based on our knowledge about the total basin and the portion of it related to Lemon Lane Landfill, Viacom estimates this dilution ratio to be at least 4 to 10 times. For example, concentrations in a PCB contaminated water conduit at the site should be 4 to 10 times higher than the PCBs in IC Spring water samples.

Viacom will next perform pump tests on the lower zone wells that have PCBs higher than the typical low flow values at IC Spring. It is believed that a pump test will draw sufficient water from the lower zone such that if the well is near a contaminated conduit, the PCB content in the pumped water will remain at, or increase relative to, the initial concentration throughout the pump test. If a borehole shows continued high levels of PCBs during a pump test, then a cross hole seismic survey will be conducted around that location. Additional boreholes may be located on those seismic targets.

The sampling station at IC Spring has been set up again to monitor PCB levels. Samples will be taken during the initial round of short low flow pump tests, although these tests are most likely not long enough in duration to impact either the flow or PCB levels at the spring. Storm data will also be collected and used to establish a new baseline for the post remedy condition at the spring.

After the installation of one or two more boreholes in the proper area, Viacom intends to perform an extended term pump test under low flow and high flow conditions while monitoring IC Spring.

B. Epikarst Investigation

The second path has been to examine zones in the rock above the water table where high PCB concentrations were found in the fill and throughout the natural soil column. The "epikarst" zone extends from the bottom of the natural soil to about 30 feet below the top of rock. Wells drilled in the epikarst in the last few months include PZ-E, F and G. Boring logs for these locations are attached. PCB results for samples from the boreholes are indicated on the boring logs.

The PZ-E location was drilled because it appeared very much like LF-6 on the resistivity images and was located in a direction that one of the fractures at LF-6 appeared to travel. The boring log for PZ-E is very much like the original LF-6, and PCB levels are high. The PZ-F location was drilled because it was in an area where a large amount of PCBs were found during the removal action. There was a significant resistivity anomaly at the location at a lower depth than at LF-6 and PZ-E, and to the west of this location few resistivity anomalies were found. PZ-G was drilled because it was in an area where a large amount of PCBs were found at the top of rock. There is a significant resistivity anomaly there and it is coincident with a narrow bedrock low that extends northsouth along the western edge of the site. PZ-F and G were largely dry holes with little to no active water found.

Certain areas of epikarst at the site have been shown to contain highly contaminated reservoirs of water. The southeast corner of the landfill has been shown to have highly contaminated water and conduits in elevations 840 to 847 and 850 to 852 (LF-6 and PZ-E). The western portion of the landfill had highly contaminated water at the soil bedrock interface, found during excavation, along a deep trough in bedrock at elevation 843 to 846, which appears to orient north-south at PZ-C and D.

To determine the amount of water that collects at these locations during both low flow and storms, instruments have been placed in wells at these locations. These instruments will continuously monitor water level, temperature and in some cases conductivity. Initial data from the first storm monitored is shown in Figures 1, 2 and 3.

Additionally, a series of pump tests will be conducted at these locations. The goal of the pump test is to measure the recovery rates of these zones near the wells to determine the aquifer yield under low and high flow conditions.

The first pump tests were conducted in March 2001. The pump test at the LF-6 location showed a very low yield. This indicates that either the initial well was improperly placed or constructed, the response itself was very small, or that the conduit is configured such that the outflow opening size is greater than the inflow opening size. Temperature and conductivity were also logged during this event. Based on the lack of any appreciable response with these parameters, Viacom believes the well was either improperly placed/constructed or that a very small response occurred during this storm at the LF-6 location. The placement of the well and its condition were evaluated. It was determined that the pea gravel was not clogged with clay and that the well screen is most likely open. It was also determined that the existing well was not in the center of the previously excavated pit and that the bottom five feet of the well screen was placed in clay that lined the bottom of the conduit. A new, larger diameter well was placed in the buried pit. The well construction and location of the new well is shown in Figure 4.

The pump test performed at PZ-C showed that the buried gravel gallery contained about 1,261 gallons of water and that recovery is extremely slow. The PCB content of the water was relatively low at 2.9 ppb. No connection was found between PZ-C and D during the test. These galleries, although only 25 feet apart, are separated by a clay layer. Attached is a preliminary test report for the PZ-C low flow pump test.

A new pump test at LF-6 is being planned that will determine the amount of water at this ,location during a storm. This pump test will consist of a recovery system with a float-operated pump. If more water reaches the well during a storm, then the recovery system will pump more water during the storm period. The pumped water will be stored and the level of the storage tank monitored continuously. This will provide a record of the well output over time.

If LF-6, another epikarst location, shows an appreciable storm response and high PCBs, the location will be dye tested during a storm to determine the dye arrival time versus the PCB pulse arrival at IC Spring.