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 RACER  Site,  Lansing,  Michigan  1,4-­‐Dioxane  in  Groundwater    For  nearly  three  years,  RACER  has  been  performing  comprehensive  environmental  studies  at  Plants  2,  3  and  6  at  the  former  General  Motors  facility  in  the  City  of  Lansing  and  Charter  Township  of  Lansing,  Michigan  (the  Site).  Under  the  oversight  of  the  Michigan  Department  of  Environmental  Quality  

(MDEQ),  the  studies  have  consisted  of  extensive  sampling  across  the  three  plants  and  collection  of  soil  and  groundwater  samples  for  laboratory  testing.    As  RACER  was  nearing  completion  of  the  investigation  in  mid-­‐2013,  a  substance  called  1,4-­‐dioxane  was  detected  in  groundwater  samples  collected  from  a  depth  of  about  65  feet  on  a  portion  of  former  Plants  2  and  3.  

1,4-­‐dioxane  is  primarily  used  as  an  additive  to  stabilize  industrial  solvents  for  storage  and  dissolves  

easily  in  water.  When  a  solvent  containing  1,4-­‐dioxane  is  accidentally  released  into  the  environment,  1,4-­‐dioxane  dissolves  in  groundwater  and  can  move  with  the  groundwater  to  form  long  plumes.  In  an  environmental  investigation,  a  plume  refers  to  an  area  of  groundwater  containing  chemicals  moving  with  groundwater.  The  size,  direction  and  speed  a  plume  travels  depend  on  groundwater  flow  

patterns.  The  investigation  work  completed  at  the  Site  has  established  the  size  of  the  1,4-­‐dioxane  plume  and  how  it  is  moving.  The  location  of  the  1,4-­‐dioxane  plume  is  shown  on  the  figure  on  the  back  of  this  page.        

The  key  conclusions  about  the  1,4-­‐dioxane  plume  at  the  Site  are  summarized  below:      

• The  1,4-­‐dioxane  plume  does  not  extend  to  the  municipal  water  supply  wells  and,  for  a  variety  of  geological  reasons,  is  not  likely  to  affect  those  municipal  drinking  water  supply  wells  in  the  

future.  Sampling  of  municipal  wells  to  date  has  not  detected  the  presence  of  1,4-­‐dioxane.      • The  plume  is  located  65  to  80  feet  below  the  ground  in  groundwater  located  above  the  

deeper  bedrock  drinking  water  aquifer.    • The  plume  is  more  than  30  years  old  and  is  generally  moving  slowly  to  the  south  at  an  

average  rate  of  50  feet  per  year.  • Groundwater  monitoring  will  continue  at  the  Site  to  verify  that  these  conditions  do  not  

change.    

RACER  has  worked  closely  with  the  MDEQ,  West  Side  Water,  the  Lansing  Board  of  Water  &  Light,  City  of  Lansing,  and  Charter  Township  of  Lansing  officials  to  develop  a  proposed  remediation  plan  to  

address  contamination  at  the  Site,  including  the  1,4-­‐dioxane  plume.  After  the  proposed  plan  is  reviewed  by  MDEQ,  it  will  be  available  for  public  review  and  comment.  RACER  will  implement  a  remedial  plan  when  approved  by  MDEQ.  

 

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RACER Trust Public Informational Meeting

Lansing and Lansing Townsip July 8, 2014

2012 Site Activities, Plants 2, 3, and 6:

As part of the Resource Conservation and Recovery Act (RCRA) Facility Investigation (RFI) Phase 2 completed between April and December 2012, the following activities were completed:

• Installation of: o 6 bedrock monitoring wells, o 15 shallow monitoring wells, and o 11 light non-aqueous phase liquid (LNAPL) monitoring wells.

• Completion of: o 81 Laser Induced Fluorescence (LIF) borings, o 52 vertical aquifer profile (VAP) and/or Hydraulic Profiling Tool (HPT) borings, and o 310 shallow soil borings.

• Installation of 4 soil gas monitoring points. • Collection of:

o 1,257 soil samples and o 221 groundwater samples (excluding routine groundwater monitoring samples).

2013 Site Activities, Plants 2, 3, and 6:

The RFI Phase 2 investigation culminated in the submittal of the RFI Phase 2 Summary Report to the MDEQ in February 2013. Based on the results of the RFI Phase 2, additional work was completed at the Site including the lower 1,4-dioxane investigation, additional investigation for metals, and investigation of various utility corridors. As part of the investigation the following activities were completed:

• Installation of 3 bedrock monitoring wells, 24 deep overburden monitoring wells and 5 shallow/perched monitoring wells.

• Completion of 41 deep VAP soil borings. • Completion of 15 shallow soil borings. • Collection of 43 groundwater samples. • Collection of 93 soil samples • Sampling of one Lansing Township municipal water supply well and one Board of Water and Light

municipal water supply well. • Quarterly groundwater sampling from monitoring wells

2014 Site Activities, Plants 2, 3 & 6:

The following has been completed to date in 2014:

• Submittal of an RFI Phase 2 Supplemental Activities Summary Report to MDEQ. • Submittal of a Preliminary Groundwater Geochemical and Plume Stability Assessment Report to MDEQ. • Submittal of a Revised Interim Groundwater Monitoring Plan to MDEQ. • Completion of a groundwater hydraulic study on the lower 1,4-dioxane plume to verify groundwater flow

and the potential effects of municipal pumping on groundwater trends at the Site. • Sampling of three additional Lansing Township municipal water supply wells and two Board of Water and

Light municipal water supply wells for 1,4-dioxane. • Submittal of a Draft Corrective Measures Study (CMS) to MDEQ.

Corrective Measures Study (CMS), Plants 2, 3, and 6:

After assessing the information from the site investigation and considering various alternatives, the proposed final corrective measures for the Site include:

• Land Use Restrictions: Limit future use of the properties to commercial and/or industrial land use only. • Groundwater Use Restrictions: Prohibit the use of groundwater for drinking, irrigation, or other

purposes on-site. • Monitored Plume Stability: Implement a long term groundwater monitoring program. Groundwater

plumes to be monitored over time to verify they are stable or shrinking. • Clean Cover/Caps: Utilize clean covers and caps to prevent potential exposure to impacted soils on-site. • Targeted Excavations: Excavations will be completed at several areas of the Site to eliminate soil and

groundwater impacts located near the property boundaries. • 1,4-Dioxane in Deep Groundwater: Installation of a groundwater treatment system to address the deep

1,4-dioxane located beneath Plants 2 & 3.

Further Evaluations/Interim Measures:

• Investigation to further define the source area for the lower 1,4-dioxane plume. The data collected will be used to aid in the design of the treatment system.

• Hydraulic testing of the lower aquifer. Data will be used to assist in the design of a groundwater treatment system.

• Groundwater monitoring will continue on a routine schedule to monitor the effectiveness of corrective measures.