2014-10-20_REPORT - M1990041

• Permit No: M1990041
• IBM Index Class Name: Report
• Doc Date: 10/20/2014
• Doc Name: U.S. EPA Region VIII Remedial Action Completion Report.
• From: CDPHE
• To: DRMS
• Email Name: MAC
• Media Type: D
• Archive: No

addressed by constructing run-on channels to prevent clean water from coming into contact with
the mine waste, and by detaining on-site storm water in a limestone-lined pond to provide
neutralization of any acidic water generated by contact with the tailings. Finally, the plans
specified select boulder placement and willow plantings along the bank of North Clear Creek,
with additional tree and shrub planting and revegetation of the stream embankment above the
ordinary high water mark to stabilize the stream bank and an earthen embankment between
North Clear Creek and the tailing ponds. Following remedial design, construction was not
immediately implemented pending development of an enforcement approach for the remaining
portions of the Superfund remedy. The Golden Gilpin Mill Site was further complicated because
of ongoing discussions between the agencies and the owner of the Site regarding potential
purchase or lease of the Bates Hunter Mine Water Treatment Plant for OU 4 water treatment.
The project was advertised for bid in March 2008. Left Hand Excavating (LHE) of Frederick,
Colorado, was the low bidder, with a bid of$135,118.15. The low bid was approximately
$70,000 below the engineer's estimate of probable construction costs. CDPHE issued a Notice
to Proceed on May 7, 2008 with LHE beginning work in early June. Construction began with
LHE preparing the site for the major tasks and beginning construction of storm water controls
and initial grading work. Final project work included completion of grading and drainage
activities, and stream bank restoration work.
The project did not experience any contractual issues or design changes during construction and
construction was substantially completed by the beginning of August. However, final
revegetation of the site was delayed until early September to avoid applying seed during the
hottest part of the summer.
IV. CHRONOLOGY OF EVENTS
9/30/91 Operable Unit 3 ROD signed
05/03/04 Remedial Design Contract approved
2006 Golden Gilpin Remedial Action restructured under OU4
01/22/08 Bid Documents let
02/28/08 Remedial Action Contractor selected
06/05/08 On-site mobilization
07/29/08 Pre-final Inspection
09/19/08 Final Inspection
09/22/08 Final demobilization
V. PERFORMANCE STANDARDS AND CONSTRUCTION QUALITY CONTROL
The Operable Unit 3 Record of Decision describes a number of objectives for clean-up activities.
These objectives can be summarized as follows:
Minimize human uptake of metals through ingestion or inhalation.
Minimize release of metals to the environment