Malburg Generating Station
Application for Certification8.15 Geologic Hazards
8.15GEOLOGIC HAZARDS
The following discusses potential geologic hazards that may occur at the MGS. The section is reported as follows:
Section 8.15.1 describes the local and regional geologic environment surrounding the MGS.
Section 8.15.2 evaluates the Project’s impact to the nearby geologic resources.
Section 8.15.3 describes the City’s plan for when the Project permanently closes.
Section 8.15.4 presents the cumulative impact from other nearby projects.
Section 8.15.5 describes any needed mitigation measures for the Project.
Section 8.15.6 describes all applicable LORS.
Section 8.15.7 lists the agency contacts used to address geologic hazard issues.
Section 8.15.8 discusses any permits required.
Section 8.15.9 lists the references related to geologic hazard issues.
8.15.1Affected Environment
8.15.1.1Regional Setting
The site is located approximately ¾-mile from the Los Angeles River in the central Los Angeles Basin. The Los Angeles Basin is located in the northeast corner of the Peninsular Ranges geomorphic province. It is in the area of transition between the Transverse Ranges geomorphic province and the Peninsular Ranges geomorphic province. The Los Angeles Basin is an active structural depression that still receives sediments from surrounding hills. This portion of the Basin is bounded by the Santa Monica Mountains to the northwest, the Whittier Fault to the northeast, the San Joaquin Hills to the southeast, and the Newport-Englewood fault zone to the southwest. Stratigraphically, the Los Angeles Basin is underlain by 100 to 200 feet of unconsolidated alluvium and an estimated 30,000 feet of sedimentary rocks (Dibblee, 1989). The sedimentary rocks that underlie the alluvium in the project area are the marine and non-marine units within the Fernando formation. The nonmarine rocks consist of sandstone and conglomerate beds. The marine rocks consist of claystone (Dibblee, 1989). Structurally the area is a downwarped basin with some subsurface folding evident.
Sand and gravel resources are present beneath much of the urbanized area along the Los Angeles River. There are oil and gas resources present in the area as well.
The site, as well as much of southern California, is within a highly active seismic region. The numerous active and potentially active faults considered capable of generating earthquakes have caused and will continue to cause seismic shaking at the site. Over 30 faults are present within a 62-mile (100-kilometer) radius of the site (Figure 8.15-1) (Blake, 2000 and CDMG, 1998). Specific faults and estimated peak ground accelerations are presented in Table 8.15-1.
8.15.1.2Local Setting
Subsurface investigations included in Appendix C, Geotechnical Investigation, reveal that the site is underlain by approximately 4 feet of fill overlying quaternary alluvium. Surface material at the site has been disturbed by grading and other earth moving activities that accompanied the construction and subsequent removal of three 48-foot to 78-foot diameter fuel storage tanks. The fill is composed of brown silty sand and gravel. The fill material contains pieces of asphaltic concrete. Alluvium is present beneath the fill and consists of poorly graded sand and silty sand. The alluvium is dense to very dense. Groundwater was encountered at 40 to 45 feet below ground surface.
Soil samples were collected from 6 feet to 31 feet below ground surface and analyzed for total petroleum hydrocarbons (TPH) range C6-C10 (gasoline), C10-C22 (kerosene and diesel), and C22-C44 (oil and heavy oil). The samples were also analyzed for volatile organic compounds by EPA Method 8260B including benzene, toluene, ethylbenzene, xylene, and the fuel oxygenates ethyl tertiary butyl ether (ETBE), di-isopropyl ether (DIPE), methyl tertiary butyl ether (MTBE), tertiary amyl methyl ether (TAME), and tertiary butyl alcohol (TBA). Except for TPH as oil at 67 milligrams per kilogram (mg/kg), these substances were not detected.
Based on the composition, distribution, and location of the sand and gravel beneath the site, these are not considered to be significant or economically viable resources. In addition, there are no known recreational geologic resources associated with the site. Since there are no known recreational resources within two miles of the site, no map is provided.
There are numerous oil and gas resources in the Los Angeles Basin. Based on review of the Munger Map Book of California’s Oil and Gas Fields, there are no oil or gas fields within two miles the project area. The closest oil and gas field is at Boyle Heights, approximately 2.5 miles to the north (Dibblee, 1989 and Munger, 1993).
Although located in a seismically active area, the site is not located on the trace of an active fault. The site will be subject to ground shaking but is not expected to be affected by a fault rupture. The Alquist-Priolo Earthquake Fault Zoning Act specifies that after a review of seismic records and geological studies, an area (termed an "Earthquake Fault Zone" area) is to be delineated to identify surrounding faults that are deemed "sufficiently active" or "well defined" so as to constitute a surface rupture hazard. This legislation was passed to prohibit the location of most structures for human occupancy across the traces of active faults and thus to mitigate the hazard of earthquake-induced ground rupture. Cities and counties affected by these Earthquake Fault Zones must regulate certain existing and future development projects within the zones through their permitting and building code enforcement (CDMG, 1999). The power plant site and pipeline routes are not within an area identified as an Earthquake Fault Zone.
Soil liquefaction is a phenomenon in which saturated, cohesionless soils (sand) temporarily lose their strength and liquefy when subjected to dynamic forces such as intense and prolonged ground shaking. Liquefaction typically occurs when the water table is shallow (generally less than 40 feet below ground surface) and the soils are predominantly granular and unconsolidated. The potential for liquefaction increases as the groundwater approaches the surface. Although this portion of the Los Angeles Basin has been identified as a site where geologic conditions are present for liquefaction to occur, a site-specific liquefaction analysis of the subsurface profile at the power plant site determined that the liquefaction potential was low.
Expansive soils are clay rich soils that have the ability to shrink and swell with wetting and drying. The shrink-swell capacity of expansive soils can result in differential movement beneath foundations. The power plant site and the pipeline routes are primarily underlain by sandy, granular soils with low expansion potential.
Landslides involve the downslope movement of masses of soil and rock material under gravity. Landslides can be caused by ground shaking, such as earthquakes, or by heavy precipitation. Generally, landslides occur on the sideslopes of hills or mountains composed of sedimentary materials. The power plant site and pipeline routes are located on flat land that is not prone to landslides. Significant mass wasting is also not evident at the site. This is primarily due to the flat topography.
Portions of the Los Angeles Basin have been susceptible to ground subsidence. Subsidence is the vertical displacement of the ground surface. Human-induced subsidence of land in the southwest portion of the Los Angeles (geological) Basin was first observed in the Wilmington oil field south of the project area in 1937. The removal of oil and gas in this and neighboring oil fields allowed the rock and mineral grains in the oil reservoirs to pack together more closely, reducing bed thickness and causing subsidence of the ground surface. There are no indications that subsidence will affect the project area.
8.15.1.2.1Recent Events Affecting Existing Site Conditions
The proposed site for the MGS is an existing operating electrical generating site, which contains five diesel-fueled generators, two natural gas-fired CTG units (previously identified as the Johnson & Heinze Diesel Plant and H. Gonzales Generating Station, respectively), and the Vernon Substation 69 kV Switchyard.
Diesel fuel is brought to the site by tanker truck. Previously, diesel fuel was stored on site in a 1,000-barrel diesel fuel storage tank. A subsurface diesel fuel release occurred in July 2001. The source of the release is believed to be a pipe running from the old diesel fuel storage tank.
The City engaged the services of Kleinfelder, Inc. of 620 West Sixteenth Street, Unit F, Long Beach, California 90313, (562) 432-1696, (“Kleinfelder”) whose principal contact is the Senior Hydrogeologist, Herbert A. Vogler, III, RG. Kleinfelder is performing the “Diesel Release Remediation” services.
8.15.1.2.2Diesel Release Remediation
Kleinfelder is removing the free-phase product and shallow impacted soil, to obtain site closure from the relevant oversight agencies, which include Cal-OSHA, SCAQMD and the City of Vernon Environmental Health Department.
Kleinfelder has procured the necessary permits for site activities, which include the grading and excavation permits from the City, notification to Cal-OSHA for excavation and demolition notification to SCAQMD.
The old diesel fuel tank has been removed from the site, as part of the remediation process conducted by Kleinfelder.
The remediation services have included the collection of asbestos and lead paint samples and a survey of the pump house building, appurtenant to the release area, for lead paint using a XRF instrument. The pump house building has been removed as part of the remediation process.
Kleinfelder is performing a one-day Cone Penetrometer Survey (CPT) using a ROST system and providing a relative site elevation control for survey points. Data is being evaluated, the groundwater collection trench system is being installed, and the appropriate reports detailing this activity are being prepared.
Material concrete debris from footings, foundations and surrounding concrete surfaces and asphalt surface material, were removed, transported and recycled.
All sewer connections associated with the pump house were cut and capped.
Kleinfelder undertook the installation of a Groundwater Treatment Compound, which included providing the necessary electrical power and connections to the site for a fully functional treatment system. A pump skid, two 2,000-pound liquid phase carbon adsorbers, and three 5,000-gallon Baker tanks (for surge tank, oil storage, and untreated water storage) were installed at the site. In addition, a parallel plate oil and water separator was installed along with the necessary piping for effluent discharge to the sanitary sewer.
A groundwater recovery trench was built to a depth of 40 feet below grade, with five 40-foot vertical risers and five Grunfos down-hole pumps.
The overburden soil and diesel-impacted soil was excavated (approximately 5,800 cubic yards) and segregated based on field screening. Dust control during excavation operations was also undertaken.
Approximately 3,200 tons of diesel-impacted soil is being loaded (with dust control procedures in place) into trucks for offsite transportation to a licensed treatment facility. The trucks are being processed through a decontamination station, as needed, prior to departure.
The site shall be restored by placing and compacting one-foot of coarse-grained soil in the base of the source removal area. A lateral injection pipe and vertical riser pipe shall be installed. An additional five feet of coarse-grained soil shall be placed over the lateral injection piping, with 400 square feet of geofabric placed over the coarse-grained soil. The remaining excavation shall be backfilled to a minimum 90% density with overburden soil and approximately 1,000 tons of clean imported soil. The area shall be graded to a uniform grade for positive drainage, with compaction certification testing.
Kleinfelder shall provide the City with weekly operation and maintenance of the groundwater remediation system. Field data and necessary samples for laboratory testing shall be collected. One carbon changeout (4,000 pounds) shall be provided and disposed of after use at the conclusion of the project.
Kleinfelder shall continue to provide the City with monthly status reports, as well as prepare a final closure report.
8.15.2Environmental Consequences
8.15.2.1Evaluation Methods and Significance Criteria
Significance criteria were developed based on CEQA guidelines and evaluated using professional judgment.
8.15.2.2Construction Phase Impacts
There will be no significant construction phase impacts to geologic resources because no significant or unique resources were identified in the project area. Geologic hazards are not expected to have significant impacts on the construction phase of the project. This is because expansive soils are not present, land subsidence is not expected to occur in that part of the Los Angeles Basin, and the topography and soil present are not susceptible to landslides. Impacts during construction from seismic shaking will be accommodated by conforming to the seismic standards specified in the Uniform and California Building Codes.
8.15.2.3Operation Phase Impacts
The Project will be subject to seismic shaking from earthquakes on nearby and distant faults. The use of standard engineering practices for building within any seismically active area requires that the project design and construction practices adhere to appropriate earthquake safety codes. The seismic standards specified by the 1997 Uniform Building Code and California Building Code will be incorporated. With implementation of the appropriate design and construction practices, no significant seismic (e.g., ground shaking and or liquefaction) impacts are expected from the Project.
8.15.3Abandonment/Closure Impacts
There are no significant abandonment or closure impacts.
8.15.4Cumulative Impacts
There are no anticipated cumulative impacts.
8.15.5Mitigation Measures
Geologic impacts associated with the construction and operation of the power plant are limited to seismic shaking. Seismic conditions relating to ground shaking will be addressed through conformance with seismic design criteria as specified in the following recommended mitigation measure:
G–1Power plant structures and equipment, as well as project pipelines, will be designed by qualified individuals in accordance with Uniform and California Building Code, Seismic Zone 4 requirements. In addition, the major structures and equipment will be designed to withstand the strong ground motion resulting from earthquakes.
8.15.6LORS
The Project will comply with all applicable LORS. This section contains an identification of the anticipated LORS (listed in Table 8.15-2) that will affect the Project. Also included is a summary of how the Project will comply with each of the LORS.
8.15.6.1Federal
The Uniform Building Code specifies acceptable design criteria for structures and excavations with respect to seismic design and load bearing capacity.
8.15.6.2State
The California Building Code (1998) specifies acceptable design criteria for structures and excavations with respect to seismic design and load bearing capacity.
The Alquist-Priolo Earthquake Fault Zoning Act identifies areas subject to surface rupture from active faults.
8.15.6.3Local
A building permit is required by the City. A building permit will be obtained prior to the start of construction.
8.15.7Agencies and Agency Contacts
Agencies and contacts relevant to MGS project geological resource and hazard issues are provided in Table 8.15-3.
8.15.8Required Permits and Permitting Schedule
The application for the building permit will be submitted 60 days prior to construction.
8.15.9References
Blake, Thomas F., 2000. EQFAULT A Computer Program for the Estimation of Peak Horizontal Acceleration from 3-D Fault Sources, April 2000.
CDMG, 1999. Fault Rupture Hazard Zones in California, California Department of Mines and Geology Special Publication 42.
CDMG, 1998. Seismic Hazard Evaluation of the South Gate 7.5 minute Quadrangle, Los Angeles County, California, Open File Report 98-25.
Dibblee Jr, T. F. 1989. Geologic Map of the Los Angeles Quadrangle, Dibblee Foundation Map DF-22.
Munger, A. H., 1993. Munger Map Book of California – Alaska Oil and Gas Fields, June 1993.
Table 8.15-1
Principal Faults within 60 Miles of the Site
(mi) / (km)
Newport-Inglewood (L.A. Basin) / 8.0 / 12.9 / 6.9 / 0.375
Elysian Park Thrust / 3.1 / 5.0 / 6.7 / 0.430
Compton Thrust / 3.7 / 6.0 / 6.8 / 0.397
Raymond / 8.0 / 12.9 / 6.5 / 0.285
Hollywood / 8.0 / 12.9 / 6.4 / 0.270
Whittier / 6.0 / 9.7 / 6.8 / 0.224
Verdugo / 9.0 / 14.5 / 6.7 / 0.242
Santa Monica / 12.7 / 20.5 / 6.6 / 0.210
Palos Verdes / 14.7 / 23.6 / 7.1 / 0.221
Sierra Madre / 16.6 / 26.7 / 7.0 / 0.199
Clamshell-Sawpit / 18.1 / 29.2 / 6.5 / 0.127
Malibu Coast / 18.1 / 29.2 / 6.7 / 0.146
San Jose / 19.6 / 31.6 / 6.5 / 0.114
Northridge (E. Oak Ridge) / 21.2 / 34.1 / 6.9 / 0.138
Sierra Madre (San Fernando) / 21.6 / 34.8 / 6.7 / 0.116
San Gabriel / 22.4 / 36.0 / 7.0 / 0.131
Chino-Central Ave. (Elsinore) / 25.4 / 40.9 / 6.7 / 0.094
Anacapa-Dume / 28.0 / 45.0 / 7.3 / 0.128
Santa Susana / 28.6 / 46.0 / 6.6 / 0.074
Cucamonga / 29.3 / 47.2 / 7.0 / 0.097
Newport-Inglewood (Offshore) / 33.2 / 53.5 / 6.9 / 0.074
Holser / 33.4 / 53.8 / 6.5 / 0.055
Elsinore-Glen Ivy / 34.9 / 56.2 / 6.8 / 0.064
Table 8.15-1 (Continued)
Principal Faults within 60 Miles of the Site
(mi) / (km)
San Andreas – 1857 Rupture / 37.1 / 59.7 / 7.8 / 0.137
San Andreas – Mojave / 37.1 / 59.7 / 7.1 / 0.077
Oak Ridge (Onshore) / 38.6 / 62.1 / 6.9 / 0.062
Semi – Santa Rosa / 39.3 / 63.3 / 6.7 / 0.053
San Jacinto-San Bernardino / 44.2 / 71.1 / 6.7 / 0.044
San Cayetano / 44.4 / 71.4 / 6.8 / 0.047
San Andreas – Southern / 45.0 / 72.5 / 7.4 / 0.078
San Andreas – San Bernardino / 45.0 / 72.5 / 7.3 / 0.072
Cleghore / 48.4 / 77.9 / 6.5 / 0.032
San Andreas – Carrizo / 51.2 / 82.4 / 7.2 / 0.056
Coronado Bank / 53.3 / 85.7 / 7.4 / 0.063
Elsinore-Temecula / 55.7 / 89.7 / 6.8 / 0.035
Santa Ynez (East) / 55.8 / 89.8 / 7.0 / 0.042
San Jacinto-San Jacinto Valley / 56.4 / 90.7 / 6.9 / 0.038
Oak Ridge (Blind Thrust Offshore) / 58.2 / 93.7 / 6.9 / 0.035
Ventura – Pitas Point / 58.2 / 93.7 / 6.8 / 0.032
North Frontal Fault Zone (West) / 58.8 / 94.7 / 7.0 / 0.037
Source: Blake, 2000