2009-09-25_PERMIT FILE - M2009076 ‎(41)‎

• Permit No: M2009076
• IBM Index Class Name: PERMIT FILE
• Doc Date: 9/25/2009
• Doc Name: Big Five Tunnel Discharge
• From: Venture Resources
• To: DRMS
• Media Type: D
• Archive: No

• and capping, runon controls, runoff controls, institutional controls, and/or retaining structures as
applicable for selected priority mine waste piles. The OU 3 ROD utilized an interim waiver of
applicable or relevant and appropriate requirements (ARARs) to defer a decision on treatment of the
Big Five Tunnel, Quartz Hill Tunnel, National Tunnel, and Gregory Incline. The OU 4 RI,
Feasibility Study (FS), and ROD have since evaluated and addressed the National and Quartz Hill
Tunnels and Gregory Incline through a combination of active and passive treatment systems. The
Big Five Tunnel requires a final decision.
The OU 3 ROD stated that: "The interim waiver of applicable or relevant and appropriate.
requirements (ARARs) was invoked for the Big Five discharge. The Big Five discharge is currently
designated as a priority discharge under Section 304 (t} of the Clean Water Act because it was
originally believed that the discharge was impairing the attainment of the water quality standards
for Clear Creek".
As specified under the Statutory Determinations portion at the end of the OU 3 ROD, the selected
alternative detailed under the OU 3 ROD was not intended to be the final remedy of the SITE.
Because the action presented under the OU 3 ROD was an interim action, the statutorypreference for
remedies that reduce toxicity, mobility, or volume as a principal element would be addressed by the
final response action for the SITE. Review of the SITE and of the interim remedy would be ongoing
as the EPA and CDPBE continue to develop final remedial alternatives for the SITE.
Treatment of the Big Five discharge after it is conveyed to the existing ARGO Water Treatment
Facility will remove it as a priority discharge under Section 3040) and meet the ARARs. Inclusion
of the Big Five Tunnel discharge in the individual control strategy and discharge control mechanism
for treatment of the ARGO Tunnel discharge will meet regulatory requirements. The interim waiver
will no longer be necessary and will be withdrawn. Therefore, addressing the Big Five discharge as
an element of the final response action at the SITE with respect to eliminating the toxicity of this
discharge to human health and the environment, as discussed in this ESD, is appropriate.
BASIS FOR THIS ESD DOCUMENT
The circumstances that have prompted and that support the significant differences between the
remedy that is proposed in this ESD and the selected remedy presented in the OU 3 ROD are
described below.
As previously mentioned, the OU 3 ROD invoked an interim waiver of applicable or relevant and
appropriate requirements for the Big Five Tunnel discharge. The Big Five Tunnel discharge is still
designated a priority discharge under Section 304(1) of the Clean Water Act. This designation was
made because the Big Five was originally identified as a discharge which was impairing the
attainment of water quality standards for Clear Creek. The OU 3 ROD suggested that this
designation of the Big Five would need to be reevaluated. The waiver was invoked "to allow time
for this reevaluation, and allow time for the development of a wasteload allocation for the Argo
Tunnel Individual Control Strategy which may include other nearby point sources such as the Big
a Five Tunnel."
Data collected since the OU 3 ROD was signed continue to demonstrate significant metals load
4