Maps from the Montana Bureau of Mines & Geology (MBMG) showing Berkeley Pit-related alluvial and bedrock monitoring sites have been added to PitWatch.Org. View snapshots of the maps below, click on an image to view a larger version, or use the links at the bottom of the page to download printable .pdf versions of the maps.
The anatomy of the thousands of miles of tunnels beneath the Butte Hill is daunting to consider and little understood by many. Important details, such as the distinction between the “West Camp” and “East Camp”, can cause consternation for many a curious observer.
The West Camp lies southwest of the Berkeley Pit/East Camp drainage and includes the Travona, Emma, and Ophir mine workings. Just as in the East Camp, the groundwater in this area has been closely monitored since the suspension of pumping in 1982 to ensure that water levels do not rise high enough to significantly impact surrounding aquifers—in this case, 5,435 feet is the magic number.
Since November 1989, pumping operations have kept West Camp water below this level. In the late 1950s, the West Camp mine workings were sealed off from the rest of the shafts and drifts on the Butte Hill by a series of barriers, or bulkheads—some made of wood, some cement.
Three main cement bulkheads block the connections between the Emma in the West Camp and the Original mine in the East Camp at the 1,600-foot level, and between the Emma and Colorado mines at the 1,400- and 1,000-foot levels.
Anaconda Company crews originally installed the bulkheads for two main reasons: 1) there were no plans to continue mining in the West Camp, and 2) they wanted to increase the efficiency of continuing mining operations in the other underground mines of the East Camp and the Berkeley Pit.
The bulkheads allowed the company to eventually reduce the volume of both groundwater pumped out from underground shafts and the area underground that required fresh air to be pumped in. However, even after the bulkheads were installed, water was pumped out of the West Camp Emma shaft until 1965.
An operable unit is a subsection of a larger EPA Federal Superfund site. There are four Operable Units (OUs) in the Butte mining district.
The Butte Mine Flooding Operable Unit, which includes the Berkeley Pit, the hydraulically-connected underground mine workings associated with the historic East Camp and West Camp tunnel systems, associated bedrock, and alluvial aquifers. The area covers approximately 23 square miles.
Butte Priority Soils is a five square mile area that includes the town of Walkerville, along with the part of the Butte Hill that is north of Silver Bow Creek, west of the Berkeley Pit, and east of Big Butte. It also includes a section of land extending south from Silver Bow Creek to Timber Butte. This Operable Unit includes residential yards, mine dumps, contaminated railroad beds, and stormwater drainages on the Butte Hill and in Walkerville.
Silver Bow Creek/Streamside Tailings Operable Unit, which follows Silver Bow Creek from just below the historic Colorado Tailings deposit in Butte and 25 miles downstream to the Warm Springs Ponds. The area includes Silver Bow Creek itself, as well as the adjacent mining wastes deposited along the creek bank and nearby floodplain, and railroad embankments adjacent to the stream that contain mining wastes.
West Side Soils Operable Unit includes lands that fall outside of the Butte Priority Soils OU. There are approximately 1,500 mine waste dumps located north and west of Butte. The dumps have not been sampled. A schedule for investigating this OU and selecting a remedy has not yet been set.
There are numerous additional operable units in the greater Clark Fork River Superfund site, which stretches from Butte and 120 miles downstream to the Milltown Dam near Missoula.
Previous issues of PITWATCH have been devoted almost exclusively to the Berkeley Pit and surrounding “East Camp” underground wells and mine workings. Another area of the underground water system called West Camp also deserves our attention.
The West Camp lies southwest of the Berkeley Pit/East Camp drainage and includes the Travona, Emma, and Ophir mine workings. Like in the East Camp, the groundwater in this area has been closely monitored since 1982 to make sure the water does not rise above a certain level—in this case 5,435 feet. Since November 1989, pumping operations have kept the water below this level.
In the late 1950s, the West Camp mine workings were sealed off from the rest of the shafts and drifts on the Butte Hill by a series of barriers, or bulkheads—some made of wood, some cement. Three main cement bulkheads block the connections between the Emma and Original mines at the 1,600-foot level and the Emma and Colorado mines at the 1,400- and 1,000-foot levels.
Anaconda Company crews installed the bulkheads for two main reasons: 1) they were finished mining in the West Camp and 2) they wanted to increase the efficiency of continued operations in the other mines and the Berkeley Pit. The bulkheads allowed them to eventually reduce both the volume of groundwater pumped and the area underground that required fresh air. However, even after the bulkheads were installed, they continued to pump water out of the Emma shaft until 1965.
Over the years, leakage has occurred through the bulkheads, but according to monitoring data, it appears that the West Camp water system remains mostly independent. The groundwater levels in its shafts are several hundred feet higher than those in the other mine workings, indicating that the bulkheads still separate the two areas.
After studying the West Camp in the late 1980s, the U.S. Environmental Protection Agency (EPA) ruled that the water in the Travona shaft could rise to an elevation of 5,435 feet without threatening human health or the environment. However, if the water were to rise above this level, EPA believes it could eventually flow untreated into Silver Bow Creek, and ARCO would face daily fines starting at $5,000 and increasing to $10,000 after 10 days.
To ensure that the West Camp water stays below 5,435, groundwater is pumped from the Travona shaft into a county sewer line and on to the Metro Sewer plant. ARCO pays Butte-Silver Bow about $30,000 a month to treat this water, depending on the volume received. Treatment mainly involves reducing the water’s arsenic content.
Recently, ARCO installed a larger main pump south of the Travona near Centennial Avenue. It can handle 100 more gallons per minute than the current pump (330 compared to 230), and it should go on line sometime this fall. The Travona pump will then become the back-up, used only when needed.
The old pump is due for some downtime, as it has been working at near full capacity for more than a year to keep up with rising water. For example, in September 1997, the Travona water hit 5,432 feet—just 3 feet below the critical mark. The current level, last measured on September 30, is 5,422 feet.
When the Anaconda Company stopped pumping groundwater out of the West Camp in 1965, the water level in the Travona quickly climbed to over 5,500 feet. Water started seeping into basements in the area bounded by Iron Street in the north, Front Street in the south, Montana Street in the west, and Maryland Street in the east. Surface water seeps were also observed north of Centennial Avenue between Montana Street and Missoula Gulch. In response, what became known as “Relief Well No. 21” was installed close to the spot where today’s new main pump is located. Keeping the Travona water more than 70 feet lower than it was back in 1965 should ensure that this case of ‘high water history’ won’t repeat itself.