Highlights

General Comments

Comments on the 
Draft Feasibility
Study (FS)

Comments on the 
Draft Remedial
Investigation (RI)

References

Complete Report
for easy printing

About Donna Boreck

Donna Boreck's 
Resume (PDF)

Technical Assistance
Grant (TAG)

General comments on Body of Remedial Investigation

PAGE	COMMENTS
2-5, 3-26	PCB migration --Storm events. It was estimated that more than 60% of the PCBs transported over the DePere dam occur during 20% of the year when discharge is at its greatest (Fitzgerald and Steuer, 1996). On page 3-26, the results of three storms were summarized with flows over 25,000 cfs recorded. The RI also noted seiche events (Bay "tides") that can affect the river up to 7 miles upstream from the mouth. These events and other input reported in the RI/FS cast doubt on the notion that the Fox River/Green Bay environment is a viable location for natural recovery.  The cohesive nature of the fine-grained PCB sediments and armouring may not be enough to keep the sediments in-place during these or even lesser events. Effective capping in the river may also be difficult to implement and maintain.
3-40 Rework	PCB migration--Non-storm events. It was noted by Velleux and Endicott (1994) that although the TSS load decreased in Zone 1, the overall PCB load in the river increased by up to 50%. In Sec. 5.5.2.1, …"Approximately 70-75% of the detected PCBs are particulate phase while the remaining 25-30% are in the dissolved phase". The finer grained cohesive sediments may take more sheer stress to get them into suspension, especially in a lake environment. But, once they are resuspended, they may travel a long way before being redeposited. Flocculation was given as a means of dropping PCBs out of the water column. But, because of how flocs form and act, the density of the floc may be close to water and settling velocity would be low. The flocs may be fragile, depending on how they are formed. The flocs may break apart easily.  Storm events can cause significant movement of PCB contaminated sediment. But after the event, the movement of PCBs in the water column may continue for a long period of time.  Given natural recovery, we may be diluting our problem, but we are sending the contamination over a widespread area. At present levels of contamination in Green Bay and the Lower Fox River, we cannot guarantee that the levels of contamination transferring to the surrounding areas are at levels that are protective of human and ecologic health.
3-42,43	Sediment consolidation. From the RI…"the upper-most layer of sediment was found to have consolidated in 7 to 14 days, … Moderate to strong winds are the most important factor for bay sediment resuspension and occur, on average, every seven days on the Great Lakes". With natural recovery--this may help dilution, but it does not say much for burial of the contaminated sediment.  As above, Green Bay may not be an appropriate environment to implement natural recovery based on the dynamics of the Bay and the level of PCB contamination in the Bay.
Figure 3-3	Lack of information on currents in Green Bay. The information on Green Bay currents provided in the RI is limited to readings taken over a short period of time. The number of actual measurements also seems to be sparse. Before any decision is made on remediating Green Bay (and that includes natural recovery of the contaminants), it is recommended that more work be done to verify actual conditions.  To assume that the sediment will settle and be buried by clean sediment discounts other factors of nature that, at times, may dominate over sedimentation. As noted above, to allow for unnecessary spread of contaminants to surrounding areas can also be considered inappropriate.
4-3	Land Use. From the RI-- "Open agricultural land and forests/woodlands comprise between 65% and 94% of land use outside of Brown County". The section continued to discuss that the area is sparsely developed. Land use can change significantly in < 100 years -- sometimes in < 10 years. PCBs are projected to be around > 100 years. Although development is presently sparse along the shores of the Bay, the land use and development around the Bay could increase significantly. What is now a low population area could have a much larger population in 50 years.  Decisions on remediation along the River and Bay need to take into account a possible increase in human development over the next 40-50 years minimum.
4-3	Bioturbation. One of the significant wildlife invertebrates listed are oligochaetes that inhabit the Lower Fox River and Green Bay . Specific species of worms were not identified in the RI/FS. A publication reporting research on oligochaetes occurrences in Lake Michigan/Green Bay (circa sampling in 1977) noted that the most abundant species at that time were Tubificids which made up > 80% of the total oligochaetes population in the Bay at depths < 40 m. From other research on oligochaetes, the burrowing depth for identified species of tubificids in Green Bay was between 3-6 cm. If the population increases, the worms reportedly compensate by burrowing deeper. Many of these species are attracted by the eutrophic conditions and higher TOC present in Green Bay, specifically Zones 2 and 3.  Assuming the worms identified in 1977 still predominate in Green Bay, bioturbation depth may be from 3 to 6 cm, possibly more depending on the density of the worm population in the area.  The PCB content of the sediment is from <100 to >1000 ppb. The TEL for benthic fauna has been set at 31.6 ppb (HH&ERA Table 7-11). The level of contamination is high enough to continue to adversely affect the benthic community for an unknown number of years. Natural recovery will be difficult -- bioturbation can continue to bring buried contaminated sediments to the surface.
7-2	The 1 ppm target level. The Risk Assessment conducted by ThermoRetec (2001) identified total PCB concentrations in sediments above 250 m/kg as a potential concern for at least 50% of all potential receptors. Yet, a 1000 m/kg target concentration has been pinpointed as appropriate. Because of potential effects on all communities, it is requested that the 1 ppm recovery target be lowered to be more protective of health.
7-5	Gradual mixing/accumulating over PCB sediments. In the RI, "…more recent sediment loading is gradually mixing with and accumulating over PCB impacted deposits". First, from the results of the time trend analysis, the analysis completed as part of this effort are not suitable for predicting future trends. Second, the decrease in PCB content is reported for the upper 4 cm. Areas in the river reportedly have been eroded to 11-18 cm depth.  The 'gradual mixing/accumulating over PCB sediments' comment is not justified given the technical findings presented in the RI/FS.
7-11	1 ppm target for recovery in Green Bay. "Considering only sediments with PCB concentrations greater than 1000 mg/kg reduces the mass and volume estimates…" As noted above, at 250 mg/kg, there is a potential concern for over 50% of potential receptors. The 1ppm level will leave approximately 70% of the projected contamination in place. The 1 ppm target for recovery in Green Bay is not based on health.
7-16	Green Bay as source of PCB contamination. The overall PCB flux through the Lower Fox River and Green Bay system includes estimate losses of 270 lbs per year into Lake Michigan and volatilization of PCBs from Green Bay surface waters at from 287 pounds to 1100 pounds.  Green Bay is now an independent source of PCB to the surrounding area. It is requested that the regulators reconsider taking action (over and above natural recovery) to remove PCBs from the Green Bay.

Submitted 14 January 2002 
To Clean Water Action Council N E Wisconsin

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