A11_QA-Attachment1-WilliamsBrosPA2005.pdf

REMOVAL PRELIMINARY ASSESSMENT

FOR THE WILLIAMS BROTHERS MINE,

BASS LAKE RD, SIERRA NATIONAL FOREST

Sierra National Forest 1600 Tollhouse Road

Clovis, CA 93611

July 13, 2004

Prepared by:

Jerome V. DeGraff On-Scene Coordinator

REMOVAL PRELIMINARY ASSESSMENT

FOR THE WILLIAMS BROTHERS MINE,

BASS LAKE RD, SIERRA NATIONAL FOREST

July 13, 2004

Prepared by:

Jerome V. DeGraff

On-Scene Coordinator

1.0 LOCATION

The site is the main adit of a gold mine and the adjacent ore processing area. It is commonly known as the Williams Brothers mine. This mine has also been referred to as the Gibbs Mine and Sally- Anne Project. In recent time, it was operated by AT&E Enterprises and USA Mining. Site elevation is approximately 4360 feet ASL (above sea level). It is located within the Sierra Nevada about three-quarters of a mile south, southeast of Brown Peak within the South Fork of the Merced River drainage.

It is represented on the El Portal 7.5-minute topographic quadrangle.

The site is located approximately 30 miles northeast of Mariposa, California (Fig. 1). It is found in the southwest 1/4 of Section 32, Township 3 South, Range 30 East. This location is wholly within Mariposa County (Fig. 2). Williams Brothers mine is at approximately 37.627 degrees North latitude and 119.795 degrees West longitude.

The site is reached by taking California State Highway 140 to the access road junction near El Portal, California. While the straight line distance from the road junction is 2.5 miles, the winding dirt road with 48 switchback turns leading from Highway 140 over the ridge to the site is several miles longer. The mine is wholly on National Forest System land and is administered by the Bass Lake Ranger District, Sierra National Forest.

2.0 SOURCE AND NATURE OF RELEASE

2.1 SITE HISTORY

The Williams Brothers mine is part of the Hite Cove gold mining district (Clark, 1970). This mine was initially developed in the 1860s around the same time as the nearby Hite cove mine (Bowen, 1957). At this time, the Williams Brothers mine was known as the Gibbs mine. Development consisted of driving three drift adits. Bowen (1957) notes that driving of these workings was partly completed in 1875. Until it was acquired by the Williams Brothers in the late 1940s, little or no work occurred for several decades due to site inaccessibility.

In 1949, the Williams Brothers used horses to move a 5-ton Gibson mill to the site. It was used for testing ore from the mine works and processing high-grade ore left on-site from previous operations.

From 1950 to December 1952, a 9-mile long road was constructed from California Highway 140 to the Williams Brothers mine. This enabled a 5-stamp mill to be completed in 1953 and processing of ore from the old waste rock dumps. It is reported that this waste rock yielded gold at $10 per ton (Bowen, 1957). The mill had a capacity of 1 ton per hour. Processing involved crushing and screening of the ore coupled with mercury amalgamation and concentrating. The resulting sulfide concentrates were shipped elsewhere for smelting.

The mining workings of the Williams Brothers mine consist of the three original adits. From uppermost to lowermost, these were 150, 75, and 200 feet long, respectively, at the time of Bowen’s field visit in September 1954. Bowen (1957) states that at the time of a field visit, these adits were being cleaned out. Also, some raising and stoping was being done above the lower adit. It was understood that considerable stoping took place within the upper adits during previous mining. Unpublished information provided in a 1993 plan of operations for the Williams Brothers mine indicates that mining and milling continued until 1964.

The mine was idle from 1964 to 1982. Limited production from the existing mine workings continued intermittently from 1982 to April 24, 1996. The primary underground work was in the lowermost adit.

In 1996, the Mine Safety and Health Administration (MSHA) received notification that surface/underground operations were suspended. Except for some processing of existing waste rock and stockpiled ore by USA Mining, no further mining activity has occurred to present at the Williams Brothers mine.

2.2 SOURCE CHARACTERIZATION

As early as September 1998, there was a concern about acidic character of water issuing from the lowest of the three main adits at the Williams Brothers Mine. A field inspection on compliance with the plan authorizing operations by AT&E Enterprises provided an opportunity to sample this discharge.

Laboratory analysis of the water found the pH to be 3.12 and confirmed the acidic nature of the water.

On June 10, 2004, a Multiline pH meter was used to sample the mine water being discharged from the lowermost adit. The device was calibrated with standards the previous day. Water was collected in a plastic cup from the discharging stream near the mine opening, near where it approaches the mill building and a point midway between these two points. This represents a horizontal distance of no more than 100 feet. Table 1 displays the results which are consistent with the 1998 water sample analyzed by BSK analytical laboratories (Appendix A). Concern for acid drainage was documented in Forest Service reports dated September 8, 2003 and June 15, 2004 (Appendix B and C).

Table 1. Meter readings for acidic drainage from lowermost adit at Williams Bros. Mine

Testing Location pH Reading Temperature (degrees C) Flowing water near adit opening 3.37 17.2 Flowing water halfway to mill building 3.44 25.8 Flowing water near mill building 3.65 28.0

Casual observation of this mine discharge between 1998 and 2004 finds little significant difference in the flow rate (Fig. 3a, 3b, and 3c). However, no observations have been made during the winter. From observations made by individuals present at the site as late as October, it appears the discharge does not cease seasonally which is consistent with the source being groundwater intercepted within the mine works. A meadow and spring are located a short distance upslope from the mine adit location.

During the time USA Mining was designated by the Mariposa County Court as the receiver for this mine, USA Mining carried out a number of actions. One was the re-processing of tailings generated from milling done by AT&E Enterprises (Mike Garoogian). This involved tailings being placed on black plastic. Little else is known with certainty about how this re-processing was carried out. The visible appearance indicates that weathering of sulfide materials is occurring. Two “ponds” of the re-processed tailings were sampled from the area immediately south of the mill building (Fig. 4). One sample of solid material was taken from the low point of each pond and sent to BSK Analytical Laboratories in Fresno, CA to be analyzed for heavy metals and cyanide. At the time of sampling in June 2004, the ponds were dry. Table 2 shows the results for several of the heavy metals and cyanide

(Appendix D). Clearly, arsenic is a concern because it exceeds the total threshold limit concentration that designates the material as being hazardous under the State of California definitions (Title 22).

Table 2. Laboratory results for solid material taken from re-processed tailings.

Chemical of Concern

Total Threshold Limit Concentration (TTLC) in mg/kg

Sample WBM-061004-1 (mg/kg)

Sample WBM-061004-2 (mg/kg)

Arsenic (As) 500 1300 1000 Cyanide (CN) ----- ND ND Lead (Pb) 1000 410 430 Mercury (Hg) 20 ND ND

AT&E Enterprises constructed an assay building near the lowermost adit. A number of chemicals were used and stored within this building. A September 8, 2003 report (Appendix C) notes a USFS letter on Sept. 11, 1998 was sent to USA Mining acting as the receiver for this mine during bankruptcy proceedings. It specifically states (Item 4), “…If any toxic materials are found, these need to be removed or treated or properly stored.” USA Mining in its Plan of Operation Status Report dated Sept. 15, 1998 stated that, “All toxic substances will be removed and/or neutralized.” (Under Physical Inspection of the Property, item j, page 6 of 9). Based on their Plan of Operation Status Report (6/17/2003), this remains undone five years later. In this document, they state that, “Any chemicals or lab materials will be removed to the upstairs facility in the Mill Building, where secure control can be maintained.” These chemicals include glass containers of both hydrochloric and nitric acid (Fig. 5). It also includes other chemicals and residues from chemical treatment that are stored in various containers within a building that has undergone vandalism and is left largely untended for most of the year (Fig. 6).

An initial inventory of the chemicals and hazardous materials present in the assay building was complied during a site inspection on June 10, 2004 (Appendix C).

A possible, but unevaluated, hazard from explosives may also exist at the Williams Brothers Mine. Three explosives storage structures are present near the mill site of the williams Brothers Mine.

They are currently locked and it is unknown if there are explosives inside. The condition of any explosives in these structures may be problematic because they have been there for six years or more. In a telephone conversation with Dan Geiger (USA Mining), Karen Nooney (Asst. Lands and Minerals Officer – Bass Lake RD) was told that a box of “weeping” dynamite was present seeveral hundred feet into the lowermost adit. To date, this information is unconfirmed. AT&E Enterprises was conducting underground mining operations in this adit in the late 1990s. Therefore, the presence of explosives left behind in this adit is entirely plausible.

In summary, the Williams Bros. Mine Site has several sources of hazardous materials. First, acidic mine drainage flows from the lowermost adit and into the natural stream system with no treatment. The pH of this water is about 3.0 and discharge takes place through at least 6 months of each year. The volume of discharge remains unmeasured at this time. Second, re-processed tailings are present at the mill site. Initial characterization shows elevated concentrations of arsenic in the tailings material. The concentrations are twice the level necessary for the material to be declared a hazardous material. Third, hazardous chemicals are present in containers within an untended storage facility at the Williams Brothers Mine. Fourth, a potential hazard from old explosives may be present from materials stored in the explosives storage bunker. There also may be explosive material in deteriorated condition within the lowermost adit of the mine.

2.3 RELEASE PATHWAYS

The nature of the release from the Williams Brothers Mine Site is through three pathways. The first pathway is surface water. The acidic water draining from the lowermost mine adit exits the site through engineered water conveyance to the natural channel leading to the South Fork of the Merced River. This pathway is also a means of release from the arsenic-contaminated tailings during period of snowmelt and intense rainfall. Movement of particles as runoff sediment would follow the same means of entering the natural channel as the acidic mine drainage.

The second release pathway is via soil contact. People or animals coming to the site could be exposed to the elevated levels of arsenic by coming in contact with this tailings material or the chemicals present with in the assay building.

The third pathway is via air. If explosives are present in the mine adit or storage structures, a detonation would release energy causing harm through the air pathway to people or animals in the area at the time.

3.0 MAGNITUDE OF THE THREAT

Evaluating the magnitude of the threat from arsenic present in the Williams Brothers Mine Site requires developing exposure scenarios for human and ecological risk assessment. The contaminant of concern is arsenic. This heavy metal is addressed for assessing risk at mine sites in a study conducted for risk management criteria at mining sites (Ford, 1996). Previous work at mining sites which were scientifically rigorous and in accordance with the Environmental Protection Agency (EPA) risk assessment guidance are the basis for risk management criteria developed by Ford (1996) for human and ecological exposure.

Due to its location, the likely individual to be exposed to the Williams Brothers Mine Site are people hunting or hiking, and Forest Service employees conducting surveys and field studies in the area. The human risk management criteria developed for the scenario of a surveyor exposed through either ingestion or inhalation of the contaminated soil most closely approximates the individuals who are likely to come in contact with the Williams Brothers Mine Site.

The risk management criteria represent the concentration at or below which people should not experience adverse health effects during their lifetimes. Risk management criteria can be used as target cleanup levels in the absence of other established levels. Table 3 gives the human risk management criteria for the contaminants of concern at Williams Brothers Mine Site under these scenarios.

Table 3. Human risk management criteria for arsenic (Ford, 1996)

Metal/Scenario Surveyor Arsenic 100 mg/kg*

*mg/kg is milligrams per kilogram (generally equivalent to parts per million, ppm)

Arsenic has a human health risk management criteria for our exposure scenario of 100 mg/kg compared to a concentration ranging from 1,000 to 1,300 mg/kg. At the Williams Brothers Mine Site, the concentrations of arsenic present exceed the higher human risk management criteria) by about 10 times based on sample analysis done to date. Therefore, it is concluded that a risk to human health exists from arsenic via the soil contact pathway at the Williams Brothers Mine Site.

Clearly, exposure to chemicals in the assay building such as hydrochloric and nitric acids and detonation of unstable explosives on the site also pose a human health risk under this scenario, too.

While the maximum contaminant level for pH in water is 6.5 to 8.5, the mine drainage water with a pH around 3.0 is not a human health risk as it is unlikely to be used as drinking water.

Assessing ecological risk involves consideration of data for the metals of concern, soil-plant uptake factors, representative wildlife receptors, body weights, and soil and plant ingestion rates for each receptor (Ford, 1996). Wildlife risk management criteria are calculated from the toxicity reference values representing daily doses of the metals for each wildlife receptor that will not result in adverse chronic toxic effect. Consequently, as long as wildlife species are not exposed to soils/sediments with concentrations of metals exceeding the risk management criteria, they are not expected to experience adverse toxic effects.

In the vicinity of the Williams Brothers Mine Site, a number of wildlife species are present.

Large mammals likely to be found in this area include: mule deer, black bear, mountain lion, and coyote. Smaller mammals expected to be in the area include: California ground squirrel, gray squirrel, spotted skunk, black-tailed rabbit, jackrabbit, dusky-footed wood rats, and deer mouse. Mountain quail are also likely to be present.

From the list of wildlife present in the vicinity of the Williams Brothers Mine Site, the receptor species which have risk management criteria developed for them can be identified from the work done by Ford (1996). These receptor species are: deer mouse, rabbit, and mule deer. Table 4 provides the risk management criteria for arsenic and mercury for these receptor species.

Table 4. Risk management criteria for arsenic for receptor wildlife species (Ford, 1996)

Metal/Species Deer Mouse Rabbit Mule Deer Arsenic 230 mg/kg* 438 mg/kg 200 mg/kg

*mg/kg is milligrams per kilogram (generally equivalent to parts per million, ppm)

The risk management criteria in Table 4 indicate that all three receptor species have risk management criteria which are exceeded by the concentration of arsenic present at the Williams Brothers Mine Site. The significantly higher concentrations measured from samples at this site clearly indicate a likelihood for wildlife to experience adverse toxic effects. The acidic mine water also would pose a risk to ecological receptors.

The Williams Brothers Mine Site poses a significant risk to humans and wildlife that are exposed to this soil medium. This threat involves exposures to humans and wildlife receptor species which exceed the conservatively developed risk management criteria by an order of magnitude or more.

Additionally, the acidic water draining from the mine enters the natural drainage system and is expected to exceed State mandate water quality goals. Stored chemicals in the assay building and, possibly, explosives present an obvious danger to unaware individuals at the site.

4.0 NECESSITY FOR REMOVAL ACTION

Circumstances under which a removal action is appropriate are defined in 40 CFR 300.415. A removal action is appropriate if it is determined, based on the following factors, that there is a threat to public health or welfare or the environment:

• Actual or potential exposure to nearby human populations, animals, or the food chain from hazardous substances or pollutants or contaminants;

• Actual or potential contamination of drinking water supplies or sensitive ecosystems;

• Hazardous substances or pollutants or contaminants in drums, barrels, tanks, or other bulk storage containers that may pose a threat of release;

• High levels of hazardous substances or pollutants or contaminants in soils largely at or near the surface that may migrate;

• Weather conditions that may cause hazardous substances or pollutants or contaminants to migrate or be released;

• Threat of fire or explosion;

• The availability of other appropriates Federal or State response mechanisms to respond to the release; and

• Other situations or factors that may pose threats to public health or welfare or the environment.

At the Williams Brothers Mine Site, the level of arsenic present poses a potential exposure to human populations likely to be at this site and poses a potential exposure to animals. The arsenic represents a "high level of hazardous ...contaminants in soils largely at or near the surface which may migrate." Finally, weather conditions at the site include intense summer thunderstorms and significant snowmelt runoff seasonally. These are conditions which may cause the tailings material with its elevated levels of arsenic to migrate or be released annually.

The acidic mine drainage from the Williams Brothers Mine certainly exceeds the maximum contaminant level for pH. This discharge from the site appears consistent with an “Actual or potential contamination of drinking water supplies or sensitive ecosystems.”

The Williams Brothers Mine Site has chemicals including acids present in the assay building. It is also possible that explosives remain in the stored structures. Some of these explosives may have deteriorated over time. These conditions would both represent a “Hazardous substances or pollutants or contaminants in drums, barrels, tanks, or other bulk storage containers that may pose a threat of release” and “Threat of fire or explosion.”

The combination of arsenic concentration, acidic water, and site location do not appear to meet the criteria for an emergency or time-critical removal action. The potential exposure of humans and animals to the contaminants present are consistent with a non-time critical removal action (40 CFR Part 300 et seq). However, the stored chemicals in the assay building and, possibly, stored explosives do appear to require a time-critical removal action.

5.0 NON-FEDERAL PARTY RESPONSE

The Williams Brothers Mine Site is wholly on National Forest System lands and mineral activities have taken place under claims filed with the Bureau of Land Management. The operators of the Williams Brothers Mine apparently created the adits before the turn of the century and are no longer viable as Potentially Responsible Parties (PRPs). Any surviving Williams brothers are likely very elderly. The more recent operators, AT&E Enterprises and USA Mining, would seem to be PRPs.

However, AT&E Enterprises lost control of the Site through a bankruptcy proceeding which makes their viability questionable. USA Mining, the successful creditor, received the claims from the Sheriff’s sale ordered by the court following the conclusion of the bankruptcy proceedings. However, USA Mining has not carried out directed actions to address some of these issues during the previous 5 years. Also, many of their assets are not currently available because the head of the company is under Federal indictment for pension fraud.

6.0 CONCLUSIONS

A removal action is necessary at the Williams Brothers Mine Site within the South Fork of the Merced River drainage. The necessity arises from the potential exposure of human and animal populations to elevated levels of arsenic in tailings and acidic waters draining from the mine adit. The level of contamination does not warrant an emergency or time-critical removal action. The situation is consistent with the criteria for a non-time critical removal action. It is also due to the presence of chemicals stored in containers on site including possible explosives. This situation is consistent with the criteria for a time-critical removal action.

JEROME V. DeGRAFF On-Scene Coordinator (OSC) Williams Brothers Mine

REFERENCES

Bowen, O.E., Jr., 1957. Mariposa County, lode mines: California Journal of Mines and Geology, Vol.

53, p. 72-187.

Clark, W. B., 1979. Gold Districts of California: Bulletin 193, California Division of Mines &

Geology, p. 64.

Ford, K.L., 1996. Risk Management Criteria for Metals at BLM Mining Sites: USDI Bureau of Land Management Technical Note 390 rev., 26 pgs.

Figure 1. Location map for the Williams Brothers mine on the Sierra National Forest showing relation to communities and features in this part of Mariposa County. The Williams Brothers mine location is noted by a red star symbol.

Figure 2. Part of the El Portal 7.5-minute topographic map showing the site of the Williams Brothers mine site and surrounding area. Note the multiple switchback road leading from California Highway 140, to the north, south to Canty Meadow and the site.

Figure 3a. Acid mine drainage from the lowermost adit of the Williams Brother mine as seen on April 25, 2001.

Figure 3b. View of the acid mine drainage visible from the lowermost adit of the Williams Brothers mine on June 25, 2003.

Figure 3c. View of the portal for the lowermost mine adit as seen from the mill building on June 10, Figure 4. Tailings adjacent to the mill building which were re-processed by USA Mining. One sample of solids from the interior of each “pond” was collected and sent for laboratory analysis.

Figure 5. Typical 2.5-liter glass container of acid present in the unsecured assay building.

Figure 6. Interior of main chemical storage area in assay building.