The Colorado Rural Water Association responded to the City of Alamosa Salmonella outbreak that was plaguing their water system.
     A total of six staff members including Rich Hayes, Randy Thielemier, Curt Armstrong, Fred Hand, Kevin Kirkpatrick, Al Tekavec and the new Mobile Training Unit (MTU), arrived in Alamosa on Friday, March 21.
     The Colorado Department of Public Health and Environment, (CDPHE), had placed the community of 9,600 residents, under a boil order after salmonella was reported in the drinking water.   At this time, there were 163 cases of salmonella reported, with 57 laboratory-confirmed.  This number would eventually rise to over 300.  Much of this day was spent formulating a plan to disinfect the system.  In an attempt to determine the cause of the outbreak, crews from Denver Water were called in to oversee the process of disinfecting the Weber storage tank and conduct a cross connection survey.
     Once the tank was cleaned, the distribution system was disinfected with chlorine using 10% sodium hypochlorite and flushed until a chlorine residual of 25 mg/l was obtained.  During this period, residents were instructed not to use the water except to flush commodes.
       As a member of COWARN Randy & Curt Installing Chem Pump, Colorado Rural Water Association’s main role was to provide technical assistance to Alamosa staff and support.
      One of the first tasks asked of the CRWA staff was to assist the operator at the East Alamosa.  This well was currently being disinfected with chlorine and had tested negative for salmonella.
      The site was being used to fill tanker trucks that were delivering water to dispensing stations to provide potable water to the Alamosa residents.  Chlorine residual readings had been low at the dispensing stations, and CDPHE asked for our assistance.
       Randy Thielemier recalibrated the chemical feed pump to bring the chlorine residual to the desired levels. Since Alamosa was one of the remaining systems in Colorado with a disinfection waver, installation of chlorine feed systems were required before chlorine could be added to the water supply.    Monday, March 24th , Curt Armstrong, assisted Alamosa staff in locating chemical feed pumps that would meet the requirements of the chlorination process.
         Farron Hall, Alamosa’s Water Superintendent, believed the fastest and best solution was to commandeer the new ProMinent chemical feed pump located at the future water treatment plant.  This new state of the art water treatment plant is a MTU  - Command Center $10.5 million facility designed to remove arsenic and is scheduled to go on line later in the summer.
         The chemical feed pump was installed at the Weber Pump Station and began feeding sodium hypochlorite into the well filling the storage tank.  Curt spent most of his effort at the Weber site training operators to calibrate the chemical feed pump and maintain the feed 25 mg/l. March 25th, the MTU was set up at the Craft Tank and became the Command Center for the project.   The MTU was used to train field crews on how to properly run the dilutions required for measuring chlorine samples in the range of 25 mg/l.  It also served as an office to CRWA, Denver Water, and the CDPHE.  Six teams were formed from COWARN members consisting of three people each and they were assigned to work two 12-hour-flushing shifts.  The goal of all involved was to complete the disinfection process of the system and return potable water back to the residents as soon as possible.
       Randy Thielemier continued to monitor tankers filling at the East Alamosa pump station.   Both Randy and Curt were assigned to shifts at the Weber pump station overseeing the chemical feed system and maintaining the 25 mg/l chlorine residual in the distribution system.  Once the disinfection process was completed, their task was to reset the pumps and maintain 2 mg/l.  The system was again flushed until this value was achieved throughout the system. Kevin setting up micro-detect Analyzer  Kevin Kirkpatrick, CRWA’s newest staff member, was assigned to setup the micro-analyzer and began measuring arsenic concentrations in ppbs.  He then trained Alamosa staff on proper operation of the instrument.  The turn around time for arsenic sample results went from several days to a few hours.
          Al Tekavec, assisted the COWARNs effort by taking GPS/GIS coordinated and setting up a data table for the sampling sites. These sites were selected by the CDPHE to test for coliform, arsenic, salmonella, and other parameters that they deemed necessary to determine that the water was potable again.  He completed a map for the team showing locations and addresses of these sites.  Testing results could then be stored in the database.
              March 26th – 31st , crews continued around the clock flushing.  The task of disinfecting to 25 mg/l and then reducing to 2 Al Collecting data mg/l was completed in about a week.  For all involved this was an amazing accomplishment considering the 49+ miles of pipe and storage system.  Certainly this was a great effort of all involved, including the staff of the CDPHE, City of Alamosa, Denver Water, Aurora, Fort Collins Utilities, Pueblo Water, Saint Charles Mesa Water, Pueblo West, CRWA and others.  As a member of COWARN, this first official event, went very well.  We are already seeing new systems signing up to become COWARN members which will make the program even stronger.
             At the time of this writing, no “smoking gun” was found as the source of the salmonella contamination.
    Systems with disinfection wavers should learn from Alamosa as I am sure we all will in months to come.
            In closing, I thank the staff of Alamosa for providing the team with all their resources and the populace for their patience and understanding.  For the most part, the citizens of Alamosa went about their daily duties knowing that this short term problem would be corrected soon and their normal life reinstated.” 

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