Case Study as part of a Web-based
Technical and Regulatory Guidance
Central City/Clear Creek Superfund
Site
National Tunnel Discharge
Gilpin County, Colorado
1. Site Information
1.1 Contacts
Michael Sieczkowski
Telephone: 913-438-5554, ext. 122
JRW Bioremediation, LLC
E-mail: [email protected]
1.2 Name, Location, and Description
Added
to the National Priorities List in 1983, the Clear Creek/Central City Superfund
Site consists of several mine waste piles, draining adits, and impacted groundwater
bodies scattered over roughly 400 square miles. Historic mining resulted
in a watershed contaminated with heavy metals, significantly impacting aquatic
life and potentially threatening human health.
https://www.epa.gov/region8/superfund/co/ccclearcreek/
2. Remedial
Action and Technologies
To ensure protection of human health and to reestablish a viable brown trout
population, several remedial actions have been performed. Waste piles have
been subject to actions including stabilization, capping, off-site disposal,
and diversion of run-on water. In many cases, acid mine drainages have been
collected and piped to reduce the potential for human contact. In a joint
project with the Colorado School of Mines, EPA, CDPHE, and Penn State are
testing various passive systems for treating the water from the National
Tunnel and mine-influenced water from a central Pennsylvania Stream. These
systems are known as “sulfate-reducing bioreactors.” Within enclosed containers
or tanks, mine water is run through carbon substrates to compare multiple
carbon substrates including chitin complex, wood mulch, corn stover, and
ethanol that enhance bacterial reactions that treat the water and reduce
metal concentrations. The pilot testing will continue through 2009.
Following the pilot test, a full-size passive system will be designed and constructed for the National Tunnel water. As these solutions require the installation of engineered wetlands or water treatment systems, institutional controls will be required for the property or properties selected for the final installation(s). These solutions also treat water discharged from the adit and will require continued operation until the flow is eliminated.
3. Performance
Barrel test operated at 6 gpd to achieve a residence time of 1.5 days (Table
3-1).
Table 3-1. Cleanup concentrations
(Modified from http://www.jrwbioremediation.com/pdf/BlackHawkDataHandout-1.pdf)
Contaminant |
Influent (mg/L) |
Cleanup Goal (mg/L) |
Ethanol |
Wood + Hay |
Corn Stover + wood |
Chitin Complex |
Acid | 5.0–6.0 | 6.5–8.5 | 6.11 | 6.71 | 6.58 | 6.98 |
Aluminum | 0.1–1 | 0.1 | ||||
Iron | 37.5 | < 1.0 | 50.0 | 20.6 | 0.26 | 0.001 |
Manganese | 20.3 | < 1.0 | 50.7 | 10.9 | 12.4 | 2.0 |
Copper | 0.02 | < 0.01 | <0.0009 | 0.003 | 0.003 | 0.002 |
Zinc | 6.51 | < 0.1 | 0.033 | 0.006 | <0.0006 | 0.009 |
4. Costs
The capital and operating costs are variable and will be compared to a bench-scale
test conducted by Penn State University. The cost of treatment during the
Pennsylvania Bench Scale study was estimated to be $0.002 per gallon treated.
5.
Regulatory Challenges
None
6. Stakeholder Challenges
Placement of the barrels in an area not readily viewable by the public was
requested, so the system was constructed in Clear Creek under a vehicle bridge.
7.
Other Challenges and Lessons Learned
It is difficult to design and operate a barrel study pilot test in extreme
winter conditions that will approximate full-scale conditions.
8. References
No information available.