March 29, 2007
The EPA has released a 12-page fact sheet covering the myriad aspects of the Milltown Reservoir Superfund site cleanup. Check it out here (PDF).
March 29, 2007
This monthly update comes courtesy of Peter Nielsen of the Missoula Valley Water Quality District.
The photo above shows the reservoir sediments from the bluff above the dam on the south side of the river. Major construction activity at the site includes construction of flood control berms along the Clark Fork and Blackfoot Rivers, which will be completed by the end of April to protect contaminated sediments from erosion during spring runoff. In this photo, the first loads of rock riprap for the flood berms are being delivered to the site by the trucks in the foreground. At the top left of the photo is the bypass channel excavation test pit, and at the top right is the sediment stockpile area which contains 40,000 cubic yards of contaminated sediments removed so far. This material is protected by a flood berm, and is planned to be shipped to the BP waste repository near the former Anaconda Smelter this fall.
This photo show exposed reservoir sediments about one mile upstream of the dam along the Clark Fork, near the old railroad bridge crossing. These sediments will be subject to scouring during spring runoff this year. Sediment, copper and arsenic concentrations will be monitored daily when turbidity levels are elevated, and if excessive scouring causes water quality standards to be exceeded, the reservoir water level will be increased to reduce sediment scour. As river flows increase, the reservoir level will also rise, helping to limit sediment scour.
This photo shows placement of rock riprap for the clerk Fork River flood berm. The upstream face of the Milltown Dam is in the background. Turbine units are being removed from the penstocks, in the powerhouse, which are large pipes that bring the flow of water from the reservoir through the powerhouse. This will allow more water to be channeled through the powerhouse this spring, reducing the water level rise in the reservoir during spring runoff.
This photo shows the discharge pipe from the dewatering pumps for the bypass channel test pit. The pumps have been turned off this week, and discharge to the river has stopped for the time being. Discharge may resume again when bypass channel construction resumes later this year. The pumps had discharged about 400 gallons per minute of contaminated water from the shallow aquifer under the reservoir, to dewater the excavation for the bypass channel test pit.
Monitoring results from groundwater monitoring wells in the reservoir area have shown a significant drop in arsenic, iron and manganese in the polluted aquifer since the project began in June, 2006. December, 2006 results show arsenic levels in monitoring wells near the reservoir in the arsenic plume have dropped by at least 50% as compared to the June results. Iron and manganese levels have dropped even more significantly. Arsenic levels in one of the most contaminated wells dropped from 339 parts per billion to 18 ppb in December. Another well went from 217 ppb to 41 ppb in December. While these results are promising, many wells remain within the range of variability over the last ten years of monitoring and it is too early to pronounce a long-term trend for restoration of drinking water quality. Wells on the west side of the reservoir have not shown improvement, and some have shown some decrease in water quality although quality remains similar to previous monitoring and below drinking water standards. Restoration of drinking water quality in the 325 acre arsenic plume area is one of the primary objectives of the Milltown project, and these initial results are very promising. The short-term improvements in water quality are likely the result of lower water level in the reservoir, reducing the water pressure through contaminated sediments into the aquifer below. Also contributing to the improvement may be the pumping of contaminated water from the bypass channel test pit and removal of some of the most contaminated sediments from the pit where they were in contact with ground water. As water levels rise with spring runoff this year, arsenic levels in the aquifer may increase again.
March 29, 2007
In March’s commentary for Montana Public Radio, CFRTAC volunteer Pat Munday looks at the language we use to describe Superfund issues. “In the Superfund process,” he writes, “the naming of things is tremendously important. Some might argue that naming is an arbitrary matter. Take cats, for instance. What’s the difference if I name my cat Gumbie, Rumpelteazer, or Gus? Well, as T.S. Eliot taught us, “The Naming of Cats is a difficult matter…” After all, like Adam in Genesis, we construct our world through the act of naming.
I think it was Joseph Kinsey Howard who first referred to the ACM as Montana’s Cheshire Cat: long after the cat was gone, it’s malevolent grin lingered in the Montana Power Company, the Plum Creek Timber Company, and of course ARCO and now British Petroleum-ARCO.
The Cheshire Cat’s grin marks the little town of Opportunity between Anaconda and the Clark Fork River; Opportunity residents are especially sensitive to the act of naming. For many years an area near their town was a toxic waste dump for the Anaconda Company. After the Company merged with ARCO and ARCO began Superfund clean up, this area became the toxic waste repository for other Operable Units—including Silver Bow Creek and Milltown Dam. Unfortunately for Opportunity residents, the ACM’s big cat box was named after their town. Opportunity residents now ask that this waste repository be renamed the British Petroleum Ponds. The county’s chief executive Rebecca Guay says, “We’re just asking that whoever owns the ponds take ownership of them.” As Opportunity resident George Niland explains, “When people type in ‘Opportunity’ on Google we’d rather have them go to Opportunity, Montana, than the Opportunity Ponds.”
Read the rest here (PDF).
March 29, 2007
The Montana Department of Transportation is looking at building a temporary bridge while it replaces the Highway 200 bridge, according to a Missoulian article. The bridge is a critical link in the Bonner-Milltown area and local residents have called for a temporary bridge to minimize disruption to the community. And even the Missoulian editorial page chimed in likewise.
March 29, 2007
A report from the US Army Corps of Engineers looks at the impacts bridge mitigation along the Blackfoot River will have on bull trout runs. The report (PDF, 3.7 Mb) finds that while dam removal will prove a great benefit to bull trout, the fish could encounter difficult passage near the I-90 piers. But the report also states that “fortunately, the current modeling results indicate areas of lower velocity near the shoreline of both banks, particularly the left bank. If the modeling results are reasonably accurate, these low velocity areas should represent challenging but sufficient conditions for upstream passage.”
The five Blackfoot River bridges were built to stand in still water and thus need to be upgraded or replaced before the dam can be removed in 2008.
March 29, 2007
The Missoulian reports that water quality monitoring in Milltown shows a dramatic drop in arsenic levels in some monitoring wells. One well that tested last summer at 339 parts per billion (ppb) arsenic had dropped to just under 18 ppb. The federal standard for groundwater arsenic is 10 ppb. Reclaiming the Milltown aquifer is the primary goal of the Milltown cleanup.
The precipitous decline is likely attributable, in part, to the draw down of the reservoir and the consequent removal of the hydraulic head believed to cause leaching of arsenic into the aquifer.
“The drop in arsenic levels in our monitoring wells was something we expected to see,” said the EPA’s Russ Forba in the Missoulian article. “When the river levels come up this spring, we may see arsenic levels in the wells increase some.”
March 29, 2007
Water quality in the Clark Fork River below Milltown dam was generally good throughout the month, although turbidity in the Clark Fork below the dam exceeded the trigger value of 12 NTU on two occasions, resulting in daily sampling of metals and arsenic. Turbidity in the Clark Fork above the dam (at Turah) was also elevated during this period. All dissolved arsenic and metal concentrations below the dam were well below warning limits and applicable standards.
Dewatering for the bypass channel continued during February, pumping about 1 cfs of discharge water into the Blackfoot River, just above the dam. Although high in arsenic, the volume of this discharge is small compared to flow in the river, and this discharge is not detectable at the monitoring station below the dam.
Drawdown in the reservoir level varied from a minimum of 10.3 feet to a maximum of 11.9 feet, depending on flow in the river. The average drawdown was about 10.8 feet.
Turbidity below the dam was measured three times per day during most of the month. Monitoring occurred weekly for suspended sediment, dissolved and total recoverable arsenic, cadmium, copper, iron, lead and zinc during the first half of the month, and daily over the second half of the month, triggered by turbidity levels. Upstream sites on the Blackfoot River and on the Clark Fork at Turah were monitored on the same schedule during this period.