Monday, November 16, 2009

Reader Comment – 11-15-09 Water Tiering

An anonymous engineer from New Zealand had a question about the potential tier ranking of a water treatment facility that he is working on the design for. He posted the question to one my blogs about HR 3258. Its an interesting question and one that will have to be asked in a lot of facility design operations. So let’s take a stab at giving some sort of answer. Disclaimers We need to start this theoretical discussion with lots of disclaimers. First off, DHS (and likely EPA will follow suit) has been very reluctant to talk about the methodology it uses to rank the security risk for chemical facilities. Without filing an actual Top Screen for the facility, your not going to get a firm answer from anyone. I’m not sure that DHS has developed an internal procedure for dealing with facilities in development. More importantly for water facilities there will be additional complicating factors. First, HR 2868 has not yet been signed into law so numbers of changes can still be made to that legislation. Next EPA will have two years to write their regulations implementing the law. As currently written the EPA is required to ‘consult with’ DHS in establishing their chemical security rules, but that leaves a lot of leeway. Finally, since our NZ Engineer specifically asked about Tier 1 and 2 rankings, I’m going to guess that he was concerned about IST complications. Since that decision, as the bill is currently written, will be made by State agencies, that will be tougher still. I would bet that states like California and New Jersey may be more likely to require IST implementation, but that is a somewhat educated guess, not a prediction. Disinfectant Decisions One of the first decisions that must be made for a water treatment facility is the determination of the disinfection technique that will be used at the facility. I am not qualified to weigh in on the actual decision, but I can offer this; do a detailed assessment of all of the alternatives and do a formal documentation of that assessment. That assessment will form an invaluable starting point for future assessments, Remember to include the costs of security and safety in the assessment. All drinking Water facilities that serve more than 3300 will come under the new federal security rules regardless of what chemicals they use for disinfection. This means that some of the security costs will be there regardless of the chemicals used. Chlorine Gas To get an idea of the tiering for a chlorine gas facility you are going to have to identify the number of people affected by a terrorist related release of chlorine gas. DHS would require you to use the total amount of chlorine on-site for making this determination. The EPA RMP would use the amount in the largest container, but I would guess that for security the EPA will go with the DHS technique. DHS does use the EPA RMP*Comp online tool to calculate the ‘distance of concern’ for a toxic chemical release. Select chlorine gas and enter the maximum on-site inventory to get that distance. Then draw a circle with that radius centered on the facility. Then determine the maximum number of people in that circle during a normal work day. DHS uses both residents and people working in the area in this calculation. The larger the number the more likely the facility is to be a Tier 1 or Tier 2 facility. Security Costs There are two types of security costs that you are going to face when you employ a toxic chemical like chlorine gas. First you need to isolate the storage from the attacker, and then you need to provide mitigation measures to deal with a successful attack. First you are going to have to have a perimeter that looks impressive and will allow for early detection of a penetration. Next, since only the largest facilities will be able to afford having a security force on site to respond to an attack, most facilities will use local law enforcement responding to an incident. That means that there needs to be additional security layers to delay an attacker until the police arrive. If you are using chlorine cylinders like our friend from New Zealand, then keep them in a secure room in a secure building. I would keep my stored cylinders in a separate secured room from the cylinders in use. The more you can isolate the cylinders, one from another, the more difficult it will be to release the total on-site inventory in a single attack. Mitigation costs can be divided into active and passive measures. Active measures work to reduce the off-site movement of the toxic cloud while passive measures alert the potentially affected population to take appropriate action. Active measures can include water deluge systems or scrubbers protecting the tank storage rooms. Passive measures would include a reverse 911 system or sirens to warn of the release and an education program to teach neighbors how to respond to the warning. In Closing… This is, of course, just a brief over view. The American Water Works Association is supposed to be developing a computerized assessment tool. They won’t release it to outsiders like me, but it will probably help in the assessment process. The Metropolitan Water District in Southern California seems to have a pretty good handle on this situation; you might want to talk to them. I hope I have been of some small measure of help.

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