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A paleontological sensitivity analysis of the El Segundo Power Redevelopment Project (ESPR) has b... more A paleontological sensitivity analysis of the El Segundo Power Redevelopment Project (ESPR) has been preformed using available published scientific literature and unpublished archival records and data. This has included the corridor areas of potential disturbance along specified, water, aqueous ammonia, and reclaimed pipeline routes as well as the designated power plant site. In addition, a limited field survey was conducted on November 3 rd , 2000, on the majority of the project right-of-way (ROW) and staging areas. Paleontological Assessment Rating (low, medium, and high) have been assigned to portions of the project areas underlain by unconsolidated and consolidated alluvial units of Pleistocene (Qal) and Holocene geologic ages. Paleontological resource sensitivity likewise varies according to geologic rock unit. Fossil vertebrate resources are considered rare in respect to the identified geological formations and geologic periods. From a regional perspective, scanty occurrences of paleontological resources from the Quaternary alluvium unit (Qal) record evidence of Pleistocene age fossil vertebrates in this part of the Los Angeles Basin-Santa Monica Bay region of southern California. Background research and prior paleontological project reports provided the scientific data necessary for prediction of the location of probable paleontological resources within the project area.
Portions of this report are confidential and are not appropriate for public distribution. Copies ... more Portions of this report are confidential and are not appropriate for public distribution. Copies of this report that include all confidential material have been provided to the California
Soceity of Mining, Mettalurgy, and Exploration (SME) Hydromettalurgy 2008, Proceedings of the Sixth International Symphosium, 2008
Boston Mine is located in the Northern Mines Region of California and is part of the Red Dog Mini... more Boston Mine is located in the Northern Mines Region of California and is part of the Red Dog Mining District, located in Nevada County, to the east of Sacramento. Hydraulic Mines are located throughout the Northern Mines and Mother Lode Mining Region. Elemental mercury was widely used at placer mines to recover fine gold in ground sluices and sluice tunnels.
Estimated annual loss of mercury to the environment during historical gold mining ranges from 10 to 30 percent, resulting in potential releases of hundreds of pounds per site. Much of this elemental mercury remains within ground, sluices, sluice tunnels, and stream sediment within the Mother Lode region. Typical features encountered at abandoned
hydraulic mines include pits surrounded by high walls, ground sluices, pit lakes, drain tunnel inlets and drain tunnels.
Free elemental mercury has been found in ground sluice, sluice tunnel, and stream sediments. Environmental impacts include mercury in surface water above water quality standards, bioaccumulation of mercury in the food chain, and direct exposure of recreational site visitors to free liquid mercury.
Regional sampling identified the drain tunnel outlet at the Boston Mine as a site of significant bioaccumulation in comparison to other placer mines that were sampled. Site specific investigations identified up to 45 grams of mercury per kilogram of sediment at the site. In addition, mercury in water from the drain tunnel outlet exceeded water quality
standards.
Characterization efforts included bulk sampling of sluice tunnel sediment to determine gold and mercury content, and a treatability study to determine if washed sediment would require special handling due to residual mercury content. Lead was identified as an additional chemical of concern as a result of the treatability study.
Evaluation of removal alternatives identified removal of sluice tunnel sediments, gravity separation of elemental mercury, stabilization of washed sediment (if necessary), sealing of the sluice tunnel floor with concrete, and surface water diversion as the recommended removal action to address this site.
The removal action resulted in recovery of 1,162 grams of elemental mercury, 264 grams of amalgam, lead, and gold from site sediment. Washed sediment was suitable for burial on site without additional stabilization; heavy mineral concentrates were stabilized with cement prior to burial on site.
The recovered mercury was recycled. Post removal monitoring is ongoing. This project highlights one way to manage mercury at abandoned hydraulic gold mines through use of existing, well understood technologies.
The Helen, Research, and Chicago mercury (Hg) deposits are among the youngest Hg deposits in the ... more The Helen, Research, and Chicago mercury (Hg) deposits are among the youngest Hg deposits in the Coast Range Hg mineral belt and are located in the southwestern part of the Clear Lake volcanic field in Lake County, California. The mine workings and tailings are located in the headwaters of Dry Creek. The Helen Hg mine is the largest mine in the watershed having produced about 7,600 flasks of Hg. The Chicago and Research Hg mines produced only a small amount of Hg, less than 30 flasks. Waste rock and tailings have eroded from the mines, and mine drainage from the Helen and Research mines contributes Hg-enriched mine wastes to the headwaters of Dry Creek and contaminate the creek further downstream. The mines are located on federal land managed by the U.S. Bureau of Land Management (USBLM). The USBLM requested that the U.S. Geological Survey (USGS) measure and characterize Hg and geochemical constituents in tailings, sediment, water, and biota at the Helen, Research, and Chicago mines...
This is a series of 10 regional geologic maps designed for printing on a 38 inch x 48 inch plotte... more This is a series of 10 regional geologic maps designed for printing on a 38 inch x 48 inch plotter. The maps accompany my guidebook series for the Mother Lode Gold Belt:
I Mariposa to Jackson
II Jackson to Grass Valley
III Grass Valley to Walker Basin
Mother Lode by David Lawler
This field guide series follows, with modifications, California Division of Mines and Geology Bul... more This field guide series follows, with modifications, California Division of Mines and Geology Bulletin 141 which was published in 1949. Incorporated for that portion of the trip from Mariposa to Placerville is information provided by Landefeld and Snow in Yosemite and the
Mother Lode Gold Belt, American Association of Petroleum Geologists Book GB68, 1990. In our guidebook, sections that are adapted from the 1949 field guide are noted by the reference "Bowen and Crippen, 1949". Those sections that are adapted from the 1990 guide are noted by
the reference "Landefield and Snow, 1990".
This field guide follows, with modifications, California Division of Mines and Geology Bulletin 1... more This field guide follows, with modifications, California Division of Mines and Geology Bulletin 141 which was published in 1949. Photographs from that publication are noted in this guidebook by the annotation “1949, CDMG”. Incorporated for that portion of the trip from Mariposa to Placerville is information provided by Landefeld and Snow in Yosemite and the Mother Lode Gold Belt, American Association of Petroleum Geologists Book GB68, 1990. In our guidebook, sections that
are adapted from the 1949 field guide are noted by the reference "Bowen and Crippen, 1949". Those sections that are adapted from the 1990 guide are noted by the reference "Landefield and Snow, 1990". In 1997, the March/April, May/June, July/August, September/October, and
November /December issues of California Geology (“CG”) contained a condensed and updated series of articles on the Mother Lode with new colored maps, and several photographs. These are noted in this guide as “1997, CGS”. Points of interest described in the text with the notation
(#00) correspond to points on the road and geologic maps of this guide with a triangular orange symbol. Several images are also duplicated from DNG CD 98-001 “California Gold Mines: A Sesquicentennial Photograph Collection”. These are noted in the photos of this guide as “1998, CGS.”
A paleontological sensitivity analysis of the El Segundo Power Redevelopment Project (ESPR) has b... more A paleontological sensitivity analysis of the El Segundo Power Redevelopment Project (ESPR) has been preformed using available published scientific literature and unpublished archival records and data. This has included the corridor areas of potential disturbance along specified, water, aqueous ammonia, and reclaimed pipeline routes as well as the designated power plant site. In addition, a limited field survey was conducted on November 3 rd , 2000, on the majority of the project right-of-way (ROW) and staging areas. Paleontological Assessment Rating (low, medium, and high) have been assigned to portions of the project areas underlain by unconsolidated and consolidated alluvial units of Pleistocene (Qal) and Holocene geologic ages. Paleontological resource sensitivity likewise varies according to geologic rock unit. Fossil vertebrate resources are considered rare in respect to the identified geological formations and geologic periods. From a regional perspective, scanty occurrences of paleontological resources from the Quaternary alluvium unit (Qal) record evidence of Pleistocene age fossil vertebrates in this part of the Los Angeles Basin-Santa Monica Bay region of southern California. Background research and prior paleontological project reports provided the scientific data necessary for prediction of the location of probable paleontological resources within the project area.
Portions of this report are confidential and are not appropriate for public distribution. Copies ... more Portions of this report are confidential and are not appropriate for public distribution. Copies of this report that include all confidential material have been provided to the California
Soceity of Mining, Mettalurgy, and Exploration (SME) Hydromettalurgy 2008, Proceedings of the Sixth International Symphosium, 2008
Boston Mine is located in the Northern Mines Region of California and is part of the Red Dog Mini... more Boston Mine is located in the Northern Mines Region of California and is part of the Red Dog Mining District, located in Nevada County, to the east of Sacramento. Hydraulic Mines are located throughout the Northern Mines and Mother Lode Mining Region. Elemental mercury was widely used at placer mines to recover fine gold in ground sluices and sluice tunnels.
Estimated annual loss of mercury to the environment during historical gold mining ranges from 10 to 30 percent, resulting in potential releases of hundreds of pounds per site. Much of this elemental mercury remains within ground, sluices, sluice tunnels, and stream sediment within the Mother Lode region. Typical features encountered at abandoned
hydraulic mines include pits surrounded by high walls, ground sluices, pit lakes, drain tunnel inlets and drain tunnels.
Free elemental mercury has been found in ground sluice, sluice tunnel, and stream sediments. Environmental impacts include mercury in surface water above water quality standards, bioaccumulation of mercury in the food chain, and direct exposure of recreational site visitors to free liquid mercury.
Regional sampling identified the drain tunnel outlet at the Boston Mine as a site of significant bioaccumulation in comparison to other placer mines that were sampled. Site specific investigations identified up to 45 grams of mercury per kilogram of sediment at the site. In addition, mercury in water from the drain tunnel outlet exceeded water quality
standards.
Characterization efforts included bulk sampling of sluice tunnel sediment to determine gold and mercury content, and a treatability study to determine if washed sediment would require special handling due to residual mercury content. Lead was identified as an additional chemical of concern as a result of the treatability study.
Evaluation of removal alternatives identified removal of sluice tunnel sediments, gravity separation of elemental mercury, stabilization of washed sediment (if necessary), sealing of the sluice tunnel floor with concrete, and surface water diversion as the recommended removal action to address this site.
The removal action resulted in recovery of 1,162 grams of elemental mercury, 264 grams of amalgam, lead, and gold from site sediment. Washed sediment was suitable for burial on site without additional stabilization; heavy mineral concentrates were stabilized with cement prior to burial on site.
The recovered mercury was recycled. Post removal monitoring is ongoing. This project highlights one way to manage mercury at abandoned hydraulic gold mines through use of existing, well understood technologies.
The Helen, Research, and Chicago mercury (Hg) deposits are among the youngest Hg deposits in the ... more The Helen, Research, and Chicago mercury (Hg) deposits are among the youngest Hg deposits in the Coast Range Hg mineral belt and are located in the southwestern part of the Clear Lake volcanic field in Lake County, California. The mine workings and tailings are located in the headwaters of Dry Creek. The Helen Hg mine is the largest mine in the watershed having produced about 7,600 flasks of Hg. The Chicago and Research Hg mines produced only a small amount of Hg, less than 30 flasks. Waste rock and tailings have eroded from the mines, and mine drainage from the Helen and Research mines contributes Hg-enriched mine wastes to the headwaters of Dry Creek and contaminate the creek further downstream. The mines are located on federal land managed by the U.S. Bureau of Land Management (USBLM). The USBLM requested that the U.S. Geological Survey (USGS) measure and characterize Hg and geochemical constituents in tailings, sediment, water, and biota at the Helen, Research, and Chicago mines...
This is a series of 10 regional geologic maps designed for printing on a 38 inch x 48 inch plotte... more This is a series of 10 regional geologic maps designed for printing on a 38 inch x 48 inch plotter. The maps accompany my guidebook series for the Mother Lode Gold Belt:
I Mariposa to Jackson
II Jackson to Grass Valley
III Grass Valley to Walker Basin
This field guide series follows, with modifications, California Division of Mines and Geology Bul... more This field guide series follows, with modifications, California Division of Mines and Geology Bulletin 141 which was published in 1949. Incorporated for that portion of the trip from Mariposa to Placerville is information provided by Landefeld and Snow in Yosemite and the
Mother Lode Gold Belt, American Association of Petroleum Geologists Book GB68, 1990. In our guidebook, sections that are adapted from the 1949 field guide are noted by the reference "Bowen and Crippen, 1949". Those sections that are adapted from the 1990 guide are noted by
the reference "Landefield and Snow, 1990".
This field guide follows, with modifications, California Division of Mines and Geology Bulletin 1... more This field guide follows, with modifications, California Division of Mines and Geology Bulletin 141 which was published in 1949. Photographs from that publication are noted in this guidebook by the annotation “1949, CDMG”. Incorporated for that portion of the trip from Mariposa to Placerville is information provided by Landefeld and Snow in Yosemite and the Mother Lode Gold Belt, American Association of Petroleum Geologists Book GB68, 1990. In our guidebook, sections that
are adapted from the 1949 field guide are noted by the reference "Bowen and Crippen, 1949". Those sections that are adapted from the 1990 guide are noted by the reference "Landefield and Snow, 1990". In 1997, the March/April, May/June, July/August, September/October, and
November /December issues of California Geology (“CG”) contained a condensed and updated series of articles on the Mother Lode with new colored maps, and several photographs. These are noted in this guide as “1997, CGS”. Points of interest described in the text with the notation
(#00) correspond to points on the road and geologic maps of this guide with a triangular orange symbol. Several images are also duplicated from DNG CD 98-001 “California Gold Mines: A Sesquicentennial Photograph Collection”. These are noted in the photos of this guide as “1998, CGS.”