2017-01-09_REVISION - M1973007SG (4)

Home Browse Search

eme ' Continental Materials Corporation Transit Mix Concrete Co. 440 S. LaSalle St. Suite 3100 Chicago IL 60605 from 8 to 11 feet at a distance of 340 feet,which is a representative distance from the proposed Wash Fines Pond to the remediation wells in use by Schlage and managed by their consultants Geosyntec. To verify their calculations BBA compared the calculated values of water level mounding to actual water level measurements in various monitoring wells adjacent to the existing Wash Fines Pond.The existing Wash Fines Pond was constructed in approximately 2010 and water level trends from that time to present are not apparent but the data does suggest that ground water levels have increased 7 to 8 feet over the lifetime of the existing pond.This suggests that water level mounding in the proposed pond will be less than the calculated volumes. See Appendix A: Ground Water Memorandum Prepared By Bishop- Brogden Associates, Inc. for more discussion regarding water mounding level changes. Contaminant Plume from Schlage Gound Water Issues As a consultant for Schlage, Geosyntec, is managing a remediation plan to reduce the PCE contamination in the area from Schlage production activities. As part of this program Geosyntec is extracting, monitoring,treating, and re-injecting water into the ground water system.The proposed Wash Fines Pond lies on the northwestern boundary of the ground water contamination plume. BBA has concluded that the proposed Wash Fines Pond will increase the ground water gradient in this area, putting more ground water into the plume,thus accelerating the travel time of the contaminates to the extraction wells.This is not expected to have any negative impacts on the remediation program. Schlage and Geosyntec monitor water levels and water chemistry in various monitoring wells and will continue to do so. Schlage an TMCC will continue to work together to share information to monitor the effects of the added ground water from the proposed Wash Fines Pond on the remediation plan. Details of the contaminant plume and BBA's findings are included in Appendix A: Ground Water Memorandum Prepared By Bishop-Brogden Associates, Inc. Summary BBA has stated their opinions in Appendix A:Ground Water Memorandum Prepared By Bishop-Brogden Associates, Inc.They are summarized as follows.The proposed Wash Fines Pond will cause some ground water mounding in the area beneath the proposed location in a range of 7 to 16 feet,with the expectation that actual values are closer to the lower end of the range.This will in turn affect the Schlage PCE contaminate Plume, but only in a way to accelerate water flow toward the treatment facility.This is not expected to have a negative impact on the remediation plan Ground water mounding in this area should be temporary due to the 5-10 year life cycle of the proposed pond. TMCC will put in the construction contract that only the amount of borrow material needed to complete the construction of the necessary embankment will be excavated from the proposed pond footprint and that it should be kept as shallow as possible inside the entire footprint.TMCC will also continue to share information with Geosyntec and vice versa in an effort to properly monitor any water mounding and its effects.