Missouri River Treatment Plant - Executive Summary

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Description of water system for Helena, Montana 
The City of Helena's Water Department (HWD) goal is to ensure customer 
satisfaction by consistently delivering high quality water today and in the future. 
The HWD serves more than 25 thousand customers with 9364 service taps including 155 fire 
lines with an average of 5.2 million gallons of water per day on an annual basis. The total annual 
gallonage from all sources for 1998 is 1.866BG* with a peak day of 12.2MG*. To supply this 
amount of water, we operate two surface water treatment plants--the Missouri River Water 
Treatment Plant (MRTP) located at 2560 Canyon Ferry Road, and the Tenmile Water Treatment 
Plant west of Helena at 1115 Rimini Road. The Tenmile Water Plant is in operation year round 
while the MRTP is used only during the summer months for peak demands.  Additional water is 
obtained from the Hale system which consists of the Oro Fino and Eureka well collectors. The 
department's two treatment plants are maintained, evaluated 
and upgraded to stay abreast of 
advancements in technology, health science and governmental regulations. 
The Helena water distribution system consists of five finished water storage reservoirs (Malben, 
Winne, Hale and Upper Hale, Woolston) and pumping stations (Forrest Estates, Hale, Eureka, 
Dahlhausen, Reeders Village) linked together with 185 miles of water transmission and 
distribution pipelines. The Chessman (530MG) and Scott (195MG) reservoirs in the Tenmile 
watershed also provide additional water for the Tenmile Water Plant during low flows. These 
reservoirs are filled with spring run off water.   
Carollo Engineers of Boise, Idaho completed a Water Master Plan Update for the City of Helena 
in April 1997. The Public Works Department has copies of the Water Master Plan if customers 
would like to review it. Phase one of this update determined that the existing Missouri River 
Treatment Plant should be rehabilitated or replaced due to age of equipment, public health risks, 
and oper 
ational safety issues. Plant replacement or rehabilitation costs were significant. The least 
costly scenario was to replace the capacity of the existing plant with high quality groundwater 
supplies if available. Test drilling of these wells has started in 1998. 
The Facility and Regulated Substances 
This is a local government owned and operated facility for the production of potable water for the 
City of Helena.  The only reportable regulated substance for the RMP plan is chlorine.  One to 
two tons of chlorine are stored at this facility in ton cylinders.  No more than two ton cylinders 
are on line at a time.  The online tanks are on isolated regulators that reduce the chlorine pressure 
to a vacuum state.  Chlorine feed equipment supplies a vacuum to the tanks allowing the release 
of chlorine to the feeders.  All feed lines supply chlorine below atmospheric pressure.  Should a 
leak develop the feeders would be unable to supply enough vacuum to continue the release of 
chlorine and the f 
eed would stop at the Chlorine Pressure Reducing Valve(CPRV) attached to the 
tank.  Each tank has its own CPRV.  No flammable substances are stored in the chlorine room. 
Two operators are required for changing chlorine tanks as part of our standard operating 
procedures.  Self Contained Breathing Apparatus(SCBA) are stored in an adjacent room on wall 
mounted quick release brackets.  An emergency repair kit is available.  A chlorine detector is 
installed in the room connected to an alarm panel and autodialer.  If an alarm condition exists it 
will call personnel till acknowledged.  All alarms and autodialers are on uninterruptable power 
supplies, batteries.  
Worst-Case Scenario 
The worst case scenario would be the total loss of one ton of chlorine through catastrophic valve 
or tank failure.  There are no mitigation controls.  Response time could be so limited(less than an 
hour)that under the right conditions total loss of one ton of chlorine is possible. 
Alternate Scenario 
Valve failur 
e or leak while tank is being changed.  The least worst case scenario would by CPRV 
failure, CPRV to tank connection, or tank valve leak.  Operators would close the tank valve thus 
shutting off the chlorine so repairs can be made. 
Accidental Release Prevention 
Operators are trained in the proper way to change tank CPRV's.  Regular maintenance is kept on 
the CPRV's, lines, and feeders.  Cylinders with exceptionally difficult or tight valves are 
returned.  SCBA's are kept in a separate room.  Operators are trained in proper leak detection and 
correction needed.  Two operators are required for tank changes or repairs.  A third operator is 
notified of any leaks and told to notify emergency responders if no communications for more 
than 20 minutes.  
Five Year Accident History 
No accidents in the last five years. 
Emergency Response Program 
As written in the plant emergency response manual.  This manual is stored on  the office desk.  
These manuals are stored in plain view by office door. 
Planned Changes 
New improvements include a groundwater supply in combination with a new Missouri River 
Treatment Plant.  This includes a new clearwell, chlorine equipment, and high service pump 
station.  Storage includes a new east side reservoir.  This new construction will begin in one to 
two years from now depending on budget restraints and final approval from City and Community 
advisory groups.
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