Written Comments on Aquifer Protection Permit for Sierrita Mine
Submitted by Nancy Freeman
P. O. Box 934
Green Valley, AZ 85622
520/207-6506

Note: Sorry--all attachments are not available on-line---yet...

Following are my comments on the serious deficiency of the proposed Aquifer Protection Permit for Sierrita Mine.

1) The Expanding Sulfate Plume
2) Effect Methods for Cleaning and Containment of the Sulfate Plume
3) Monitoring for Toxic Chemicals, Volatile Organic Chemicals and Radioactive Chemicals

My biggest concern is that many of the levels set as the Maximum Contaminant Level for toxic regulated chemicals have already been exceeded at the Points of Compliance, particularly for the Radioactive Chemicals. This is a clear indicator that something has to be done immediately.

It will cost money now, but it will save money in the future. It’s the simple folk wisdom: “A stitch in time saves nine.”

It is simply inconceivable and unacceptable that the Department of Environmental Quality has allowed this continued destruction of a natural resource, especially water in a desert state and in a sole source aquifer.

Something has to be done NOW!
The residents of Green Valley—and Arizona— will accept nothing less.

THE EXPANDING SULFATE PLUME

The plume has been growing, is growing, and will continue to grow.

1) Community Water is no longer pumping 2 acre feet per year out of the plume.
The daily pumpage was so low, any cone of depression will be mitigated in a short time.
2) Phelps Dodge has geared up its operation from 50 to 100 percent. Since the flotation method that puts slurry into the pond is their major form of extraction, the contaminants will be doubled too.
3) The attenuation capacity of the Calcium Carbonate in the aquifer is less since it has become supersaturated with contaminants.
4) Recharge from the tailings impoundment:

Water Budget study from Mines Task Force study published in 1983
“…. Information in the files of the Arizona Department of Water Resources indicates that the volume equivalent to about 25 to 30 percent of mine pumpage, on the average, is returned to the groundwater from the tailings ponds in the Sahaurita-Continental area.” [Page 43]

5) The attenuation capacity of the aquifer in the area of the plume is lessening so that the toxic elements of the plume are also increasing.
6) The POC wells for sulfate must be at the monitoring wells between the berm and Green Valley, MH 11, 12 and 13. That’s what they were put there for!

Attached are two maps of the sulfate content in groundwater. I realize that both of these maps are quite dated—I don’t know why ADEQ has not asked for more current ones. The more complete analysis on Attachment A (1982) shows that the impact of the plume is not in simple concentric rings as shown on Attachment B. Although the levels have increase at the monitor wells at the dam berm some 300 to 400 mg/ltr and some 250 at monitor well MH-12, the greatest change has been the size and the northern movement of the plume. The maps also indicate that The Experanza Well Field and Community Well #7 are more likely being impacted by the Twin Buttes operations.

Attachment A: Sulfate Content in Water from Wells in Vicinity of the Duval Sierrita Pond (Fall 1982)
Attachment B: Sulfate Concentrations, 1993 (Errol L. Montgomery & Assoc. Inc.)

EFFECTIVE METHODS FOR CLEANING AND CONTAINMENT OF SULFATE PLUME

We need effective methods for the plume’s containment that are not heavy water users. The drawdown on the aquifer is now 2 to 3 feet per year. Almost half of the usage is from Phelps Dodge mining operations. It is insane to use high water volumes to attempt to control pollution in a sole source aquifer—especially, when the Interceptor Wells are not working effectively.

It is simply not logical to start putting money into cleaning up the plume when its existence has been known and measured since 1980 (Mines’ Task Force). It is partially ADEQ’s responsibility that Phelps Dodge Sierrita has had to keep throwing money into monitor wells and reports, rather than doing something about the problem.

Two effective ways of cleaning and containing the plume that do not use copious amounts of water:

1) Clean and capture filtration systems.
2) Trenches that catch and then treat the seepage.

MONITORING FOR TOXIC CHEMICALS AND RADIOACTIVE CHEMICALS

1) There are regular spills of Sulfuric Acid at the plant. The officials claim that they move the contaminated soil. Where do they move it to? What is the impact on Groundwater? I have attempted with no success to have ADEQ and EPA look at the figures to determine if they were what were causing the spikes in the sulfate data at all the Community Water Company Wells.

I noticed these spikes and wondered what caused them. They did not appear to be testing errors because
a) They did not necessarily occur on the same test date.
b) There was a gradual increase, a spike, then a decrease.
The sudden increases, then lowering of the levels, are not indicative of a traditional sulfate plume.

The problem in analyzing the data was finding the time that the sulfuric acid would flow from the leach area to the wells. I finally found the magic number!
It takes 39 months. Of six correlations available, four in a row were 39 months, then 24 months, then 21 months. It could be expected that with time the spills make a drain to make the trip faster.

See Attachment C: Community Water Well #8 Data
See Attachment D: Hazardous Material Incident Logbook
See Attachment E: Date correlation of Sulfuric Acid Spills & Spikes in Sulfates in Community Water Well 8

2) The use of toxic chemicals in the Flotation Process. These chemicals are hydrocarbons with complex configurations, but some are as simple as kerosene. It is claimed that the volatile organics used in the Flotation Process do not go into the slurry that goes into the tailings impoundment because they are filtered out before the slurry goes to the impoundment. This is not a sound analysis.

a) Filtration is not a treatment technology for volatile organics. Treatment is pushing air the solution which releases the volatile chemicals into the air.
b) The amine compounds break down into nitrates, so the presence of nitrates in the groundwater is an indicator of travel of these compounds which can be very mobile in an oxygen solution (H2O). The tailings slurry water has a Nitrate level of 18.6 mg/ltr. On site monitor well BW-2 has a level of 97.5, while monitor wells at the berm, MH-14 and MH-16, show levels of 12.8 and13.2, respectively.

See Attachment F: Tailings Slurry Water
See Attachment G: Monitor well data for BW-2, MH 14 and MH-16

c) From the sparse data that I have on VOC’s there is an indication that there are regulated VOC’s over the “Maximum Contaminant Level” at monitor wells. See Attachment H.

Chemicals Used in Flotation Process

1) Alky Aryl Oxime
2) Petroleum Distillate
3) Sulfosuccinate surfactant
4) Alkyl xanthate salt
5) Nalco 7873—no chemical formula given
6) Alcohol/hydrocarbon


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