View Full Version : Need help with Gross Alpha
12-31-2009, 12:06 PM
I'm in the process of buying a house with well water, and water testing showed all is good EXCEPT it failed for gross alpha :( :
Gross Alpha (initial) 16.56 pCi/L (limit is 5 pCi/L)
Gross Alpha (final) 15.84 pCi/L (limit is 15 pCi/L)
My research so far suggests there is a good chance this is caused by excessive levels of both radium AND uranium:
Combined radium 226 & 228= 6.0 pCi/L (mcl is 5 pCi/L)
Uranium= 37ug/L (mcl is 30 ug/L)
At first, I thought I was just lucky finding a house on a former nuclear test site! I have come to learn this is common in my area, something to do with the local geology. There is an old, out of service water softener in place, so these test results are for raw water. My hope is to replace the old system with a new cationic system (looks like an old Fleck setup), to control the radium. Does anyone have a crystal ball that can predict if this will help get my gross alpha numbers into the "passing" range? Are there any particular resins that are recommended for these contaminants?
Some people have suggested if this doesn't do the job, I may need to install a second anionic softener for the uranium, but I am getting mixed signals on this (concerns about metal pipe corrosion running "demineralized" water). I would rather install a POU reverse osmosis system (to control the uranium) for our drinking water, but not sure if my township will accept this.
If anyone has any experience to share, it would be most appreciated. All this radiological stuff has me very nervous.
12-31-2009, 02:25 PM
Not my area of expertise (if there is one!)...but keep in mind if it is from radon, that is a gas, and I doubt a softener will do much of anything with it. the techniques I've heard use a mechanical means to agitate the water (flow it say in a spray) to promote expelling the radon. Then, you'd need another storage tank and pump to supply the house. If there are actual mineral particles, you might filter them out, but then the filter media would become radioactive! not something you'd want to handle as it concentrates the material.
Hopefully, someone who has successfully dealt with this knows how to resolve your problem.
01-01-2010, 02:10 PM
My understanding of the gross alpha test results suggests radon is not a big factor here. As it was explained by someone much smarter than me, radon has a short half life (3.8 days). The two tests are done 48 hours apart; if radon was a big factor, there should be a bigger difference between the initial and final test results. I hope this is right, because I'd rather not have to deal with an aerator if I don't have to.
I've done more info surfing since my first post, and have found a few places claiming success removing both radium and uranium by blending 90% cationic resin (for the radium) and 10% anionic resin (for the uranium) in what sounds like a conventional water softener.
I'm trying to find out how one does this; was hoping to find this as a "pre-mix", but not sure if that's an option. I've been finding bits and pieces of relevant info, but it's been burning up alot of good vacation time!
Anyway, thanks for the response. I'll keep adding what I find, in case anyone is having a similar problem.
01-01-2010, 08:05 PM
I think I would be looking at another house
Uranium and Radon both? Here is a well you will never ever feel comfortable with, especially if you have children. No matter how you treat this it will always be in the back of your mind.
01-01-2010, 09:45 PM
Some anion resins are regenerated with sodium and some anion uses chlorides. So they are put in a softener and regenerated with sodium chloride.
For what you want to remove, there may be pretreatment requirements for the anion resin that would have to be met or the equipment wouldn't work or work for long.
01-02-2010, 04:54 PM
Well Peter, it's obvious you've never met my kids ;)
But seriously, we did consider walking away from this house until we started doing our homework. Turns out "gross alpha" is alot more common than I had realized. When we bought our current house 15 years ago, GA wasn't part of the testing requirements. Now that it is, I suspect there will alot of people looking for ways to remediate. Luckily, ion exchange seems to be a very effective means of remediation.
Gary, thanks for responding. Could you share what pretreatments you would suggest for the anionic resin? What do you think of the 90/10% mix of cationic/anionic resins? I picked this up from a technical book hit (way over my head), but it sounded right for my situation. Don't know how well tech book translates into real world use.
I've visited your site and have been working on calculating my system capacity needs. I can't do it all just yet, since I'm not in the house yet. Quick general question for you: what's the down side (if any) of having "too much" capacity? I have a family of 5, but my kids are older; in a year we'll be four, a few years later three, etc.
01-02-2010, 06:11 PM
Pretreatment depends on what anion resin you use.
A too large softener runs the risk of channelization of the resin bed, meaning you get hardness through the softener and the only cure is a regeneration; which ruins your salt and water efficiencies. You don't have to be in the house for me to size a softener for you.
01-18-2010, 10:13 AM
One last question (well, maybe two...) on this mixed bed approach. Any concerns (at this 90/10% blend) about alkalinity changing? I've seen a few sites mentioning this being an issue when doing a two tank approach (one cation one anion), not so good for the copper pipes.
Here's a stretch question. It looks like the anionic resins have a very strong affiinty for uranium. Does anyone offer an anionic POU cartridge? This could leave the softener as a conventional setup (in my case, to soften water and remove radium), and put the uranium treatment where it's needed, at the kitchen sink.
I'm running out of questions, I promise. Until I install the softener, of course...
01-18-2010, 01:02 PM
Using anion resins depends on what and how much of it is in the water, how much water is going to be used, the peak demand flow rate and then what pretreatment is called for based on the anion resin being used. Usually anion resins 'float' on top of cation resins (they are lighter) so they see whatever is in the water first and do not mix with the heavier cation resin. Usually you talk X cuft of anion on top of X cuft of cation; they don't mix so there is no percentage used.
What you are thinking of doing is called top dressing a softener. In some cases you can do that and others not. Your situation probably is one you can't do that with but I have no experience in gross alpha. Top dressing usually doesn't work very well for very long.
Any media can be put in a replaceable cartridge filter but not many dealers will have a source of the fillable cartridge so they would order the completed cartridge from a supplier. I wouldn't suggest that because there is no good way other than a gallon meter to know when to change the media or buy a new cartridge.
01-18-2010, 02:46 PM
Clack WS1 Smart Memory Metered Uranium Removal System
12x48" Mineral tank, 2.0 cubic feet of A-300E resin, 1.05"o/d riser tube, Clack WS1 electronic, turbine metered control valve with 3/4" or 1" inlet/outlet PVC or brass connectors, 18x33" brine tank with grid and 2310 float assembly safety overflow grid plate, brine well and brine tank to valve tubing funnel. Floor space required is 30 x 18 x 62". Includes bypass valve and resin funnel.
It ain't cheap at around $ 2,100.00