ANTIMONY in Drinking Water History and Remediation Efforts
1. Antimony detected in April 1995 by routine tests in the Bay City Tunnel at Alta and the Wasatch Drain Tunnel at Snowbird. Both are the major sources for Snowbird and Alta. (Peak population served in winter approx. 5000)
2. Regulated by EPA just prior to 1995 in the Phase 5 rules of 1992 (Promulgated in vol. 57, No.138, of the Federal Register 40 CFR Parts 141 and 142)
3. Antimony Limit set at 6 parts per billion. Alta averages just under twice the limit, and Service Area #3 is approximately 1.5 times the limit.
4. Antimony background:
A. Standard based on old obscure 1970s paper on Antimony in food.
B. Dr. Robert Okey (U.ofU.) research in 1996 demonstrates studies that place Antimony toxicity at levels equivalent to Copper, or over 200 times greater than the current limit.
C. 1997 Study on Rats recommends a 500 part per billion level to achieve no observed adverse effects level.
5. Service Area #3 and Alta receive EPA exemption for 5-year period beginning October 1997. Solution must be found prior to the expiration in 2002
6. We have pilot tested 16 different treatment technologies to date. Some were unsuccessful at removal, others have had various levels of success but the costs are prohibitive.
7. Methods tested that are unsuccessful:
a. Oxidation Filtration, with Chlorine (current treatment process)
b. Oxidation Filtration, with Ozone
c. Ferric Chloride, Oxidation Filtration
d. Ion Exchange conventional resin
e. Ion exchange using custom made resin for Antimony
f. Granular Activated Carbon (GAC)
g. Electro Precipitation Filtration (low energy using iron alloy electrodes)
h. Electro Coagulation Filtration (higher energy aluminum electrodes)
8. Methods tested that are successful but very expensive:
a. Conventional high pH treatment using IDI Densideg solids contact clarifier (repeatability is questionable and chemical usage very high).
b. Reverse Osmosis using sea water membranes (large waste of water) high energy costs
c. Reverse Osmosis using VSEP (vibrating membrane) process high-energy costs.
d. Reductive Iron or Aluminum Chemistry MSE inc. Mine water remediation technology (sensitive process, high chemical usage, high sludge generation).
e. Catalyzed Cementation process MSE inc. 25mg/L residual iron after process overloads current filters.
f. Activated Alumina treatment Bench studies indicated removal to 10,000 bed volumes, however pilot work only able to confirm 2,000 bed volumes. Not cost effective
g. Activated Alumina treatment with pH adjustment only increased filter run time to 2,500 bed volumes
9. Granular Ferric Hydroxide, GFH a proprietary media manufactured by Wasserchemie of Germany has had the best results so far. After 8 months and 35,000 bed volumes it hit 0.0061, then went below the limit . Stopped on 12/18/01 (1 year) 51,000 bed volumes, 225,000 gallons, 0.0057. This technology is very promising.
10. Bayoxide - Grannular ferric media, Started on 12/18/01. Projected to go up to 165,000 bed volumes. No test results yet
11. Alternative Water Sources are non-existent (i.e. water wells).
12. Blending of sources unrealistic due to lack of quantity in other sources
13. Piping from the Valley is cost prohibitive.
14. Funding for an Antimony toxicity in drinking water study?
15. Changing The EPA limit?
16. The Town of Alta has spent over $30,000 and the Service Area has spent over $95,000 during the last two years in an attempt to find a solution.
17. Cost of these treatments remains a problem. Water rates at the Service Area were recently raised 10%. Current water rates are approx. $4.00 / 1000 gallons, the least expensive Antimony removal process could significantly add to this cost.
18. Some of these processes require significant quantities of chemicals (Ferric chloride, Sulfuric acid, Sodium Hydroxide, Lime, etc.). A great deal of sludge is also generated in certain processes (up to 120 tons per year). There is concern with hauling these chemicals up the canyon in quantity and hauling the waste products down. One accident involving these materials could cause great harm to the sensitive watershed.
19. Work continues