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The original item was published from 12/7/2016 2:59:59 PM to 12/7/2016 3:02:10 PM.

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Water and Sewer Division

Posted on: December 7, 2016

[ARCHIVED] Latest Update for Hexavalent Chromium (Chromium-6)

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     The Water Department continues to sample and gather relevant information on Chromium-6 as it relates to our drinking water supply.  On November 15th, we resampled all our well sources along with our finished water as it enters into our distribution system and received results back last Friday, December 2nd.  The finished water going into the system was at 2.1ppb, which is lower than our previous results of between 3.4 – 4.1 ppb.

     On Monday, December 5th, we started the installation of monitoring wells to help us determine the source and direction of this material and how it is entering into two of our main wells. As of Tuesday, December 6th, the two ground water table wells, set at 20 feet in depth, were installed and the casing for the deep well, set at 89 feet, was set in place. Work will continue on the second deepest well, set between 72-75 feet and we are looking for completion by the end of this week.

     After development of these wells are complete, we will start to compile sample results to help us better understand the migration of Chromium-6 and how our wells are influenced. In the interim, as we await results, we have spent time researching information and speaking to personnel involved in hexavalent chromium treatment and abatement in Southern California. Southern California is basically the leader in research and treatment of hexavalent chromium, mainly because of the large scale contamination problems in Hinkley, California, which was made into the movie Erin Brockovich. Secondly, in that area of the country, hexavalent chromium is naturally occurring in the rock formations supplying ground water sources. Typical natural levels in many areas are between 20-30ppb. California has the only state standard for hexavalent chromium in the country, which is currently set at 10ppb. All water suppliers in the State must comply with this standard by the year 2020. Due to this, much work is being done on treatment methodology and aquifer abatement in the southern part of the State. Work related to this in the Northeast part of the country has been mainly limited to landfill and superfund site remediation.

     We greatly appreciate the opportunity to speak with utility personnel from various water companies in Southern California actively involved in evaluating and installing treatment technologies, along with Pacific Gas and Electric field operations people on their abatement efforts in the Hinkley, California plume mitigation and the technologies currently being used and new innovations being evaluated. Their extensive field experience and knowledge has helped us immensely in better understanding the characteristics of hexavalent chromium in relationship to water supplies.

     Listed below are our latest results from November 15th. We also sampled our finished water a second time with the two highest level wells off, to eliminate any other outside source. In a period of three hours, we were able to drop our finished water level from 2.1 to 0.38ppb. Also, a common question asked by our residents pertains to which wells serve their area of town. In response, all the wells are mixed together in a centralized treatment process and pumped out uniformly. Here are the current Chromium-6 testing results, including Finished Water;

  • Finished Water – 2.1ppb
  • Finished Water -  0.38ppb *(Home Wells 6-3 & 6-4 Turned Off)                                              
  • Home Farm 6-1 – 0.12ppb
  • Home Farm 6-2 –  < 0.02ppb                                            
  • Home Farm 6-3 – 6.1ppb  
  • Home Farm 6-4 – 10.0ppb
  • Sewell #4 – < 0.02ppb                                                                                                                                     
  • Lambert’s 3-3 – 0.05ppb
  • Lambert’s 3-2 – 0.03ppb

 Questions may be directed to the Water Department at 508-841-8506.

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