Art Willdens Final BF 2005 Presentation2

Transcription

History & Technical Issues of
El Paso County’s
Mill Sites Brownfields Corridor
Portland Mill Circa 1906
Presentation To:
Brownfields 2005
Intensive Use
of
Mine Scarred Lands
November 3rd, 2005
Art Willden, P.E.
Presentation Agenda

History of the Cripple Creek Mining District
El Paso County Mill Sites Corridor
Mill Site Legacy
The Portland Mill Site Example
Use of GIS as Historic Research Tool
Challenges
The Cripple Creek Mining District
Established in 1890
Still Operational Today
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4th Largest Gold Producing Camp in the world
By 1899 Produced $59 Million
By End or Gold
Rush Produced
$432 Million
Ore Transported
to Colorado
Springs by the
Colorado Springs
& Cripple Creek
District Railway
El Paso County Mill Sites Corridor
Golden Cycle Mill
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Operated from 1895 to 1907 When It Burned;
Rebuilt and Operated Till 1949
Used Cyanidation & Amalgamation Techniques;
9 Treated ≈ 13.5 Million Tons of Ore.
Colorado-Philadelphia Reduction Works:
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Operated from 1896 to 1912
9 Concurrent Chlorination & Cyanidation Techniques Used
The Standard Mill:
¾ Operated from 1901 to 1911
9 Concurrent Chlorination & Cyanidation Techniques Used
Mill Sites Corridor (Cont.)
The Portland Mill:
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Operated as Mill: 1902 to
1918:
9 Chlorination: 1902 to 1907;
9 Concurrent Chlorination &
Cyanidation: 1907 to 1918;
and,
9 Generated ≈ 1.5 million Tons
of Tailings.
¾ Operated by U.S. Government
from 1918 to 1921:
9 Researched Potash Recovery
For Explosives.
Mill Site Legacy
Likely effluents from various stages of operations at the Mills
Operational Step
Likely Effluent(s) Likely Destination
ore delivery crushing and
blending
Ore escapes
Near rail stations and
crushing facility and
blending areas
Roasting fumes
SO2, Te, Te2O3, As2O3, mineral
flue
Te sublimate, Arsenic and
flue-dust into tailings pond
Chlorination
No permanent effluents
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Table concentration
No permanent effluents
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Cyanidation
Sands and possibly solids like
K4Fe(CN)6
Tailings pond
Melting
Slags (non hazardous)
Tailings pond
Assays
Pb-fumes; also some Phbearing slags
Pb and PbOx disperse in the
atmosphere; slags go to
disposal
Power plant
Coal combustion slags (nonhazardous)
Near plant or tailings pond
Legacy Characteristics

Crushing, grinding, blending, roasting, chlorine-gasleaching, and cyanidation were the primary techniques
utilized for the recovery of gold from Cripple Creek,
Colorado ores.
Structures of the minerals were broken by roasting,
making gold available to chloride and cyanide
solubilization.
Both sulfide precipitation and reduction by zinc metal
(the Merrill-Crowe method) were used in the recovery
of gold.
In the lifetime of the mills, millions of tons of tailings,
consisting mainly of silica and alumina-rich sands, were
generated.
Legacy Characteristics
(continued)

The ores used and methods employed had the potential
to generate products such as tellurium, arsenic,
potentially some lead as well as zinc, sulfate ion and
chlorides.
In the 50 to 80 years that have elapsed since the start
and closure of the mills, the tailings have been
disturbed numerous times which will have allowed the
leaching-away by weathering and natural waters, of a
significant percentages of their soluble constituents
such as zinc, lead, arsenic and cyanide-containing
compounds.
Example - The Portland Mill Site:
Currently Occupied by the Penrose Equestrian Center
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A Multi Use Facility:
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Programs For Low Income &
Handicapped Children;
Numerous Equestrian Events;
Motor Sport Events;
Trade Shows; and,
Concerts.
Parks & Open Space
Boarding
Barn
Penrose
Stadium
Indoor
Arena
Show Stalls
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Trail Connection to National
Forest & Pikes Peak;
9 Urban Wildlife Habitat; and,
9 Urban Wetlands.
Penrose
Site Boundary
Historic Background
Site History & Equestrian Center Background:
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1934 to 1939 - Leased By Mill Tailings Recovery Corp;
1938 to 1957 - Portion of Property is a Dump;
1953 to 1977 - Portion of Property is a Shooting Range;
1974 to 1994 - Penrose Facility Developed;
1995 - Listed On CERCLIS;
1995 to 1997 - PA & FSI Performed;
1997 - Results of “FSI” Concluded:
9 Conditions Don’t Merit Inclusion
on the “National Priority List”
9 Concentrations Don’t Merit
Removal “CERCLIS”.
Data Management Issues:
Sources of Historic Use Information Included:
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Historic USGS Portfolios & Topographic Maps;
Portland Facility Blueprints and Surveys;
Sanborn Fire Insurance Maps;
Site Photography;
Aerial Photography;
Planimetric Data;
Geologic Hazards;
Flood Plain Data;
Utilities;
County Assessor Data;
Challenge - How Do You Tie This Data Together?
Challenges Example
The Portland Mill Site:
Currently Occupied by the Penrose Equestrian Center
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A Multi Use Facility:
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Programs For Low Income &
Handicapped Children;
Numerous Equestrian Events;
Motor Sport Events;
Trade Shows; and,
Concerts.
Boarding
Barn
Penrose
Stadium
Indoor
Arena
Show Stalls
Parks & Open Space
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Trail Connection to National
Forest & Pikes Peak;
9 Urban Wildlife Habitat; and,
9 Urban Wetlands.
Penrose
Site Boundary
The Data Management Solution
Geographic Information Systems (GIS)
Former
Former
Mill Bldgs
Mill Buildings
Landfill
Tailings
Shooting
Range
Regulatory Challenges
Obtaining No Further Response Action Planned
(NFRAP) Designation:
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Age of Site Resulted in Relatively Low Observable
Concentrations
Bioavailability of Arsenic in Tailings Is Low
Portland Mill Site NFRAP’d
Resolution of the Applicability of the RCRA Mining
Waste Exclusion (Bevill Amendment) To Milling
Tailings