Chapter 3.2 2 Geology, Seismicity, and Soils

Pebble Beach Company’s DMF/PDP Draft Environmental Impact Report

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Chapter 3.2 1

Geology, Seismicity, and Soils 2

Introduction 3

This chapter provides a discussion of the geologic, seismic, and soil conditions 4 that currently exist within the project area. The potential impacts of the Proposed 5 Project related to existing geologic, seismic, and soil conditions are also 6 evaluated in this chapter, and mitigation is proposed where applicable. The 7 environmental setting used as the basis for evaluating the impacts of the 8 Proposed Project is at the end of this chapter. The regulatory setting is in 9 Appendix C. 10

The description of existing conditions and subsequent impact analysis presented 11 in this chapter are based on a review of maps and information published by the 12 U.S. Geological Survey (USGS), the California Geological Survey (CGS) 13 (formerly the California Division of Mines and Geology), the County of 14 Monterey, the Natural Resources Conservation Service (NRCS), and on-site-15 specific geologic and geotechnical reports prepared for the various development 16 sites that are part of the Proposed Project. 17

18

Monterey County Chapter 3.2 Geology, Seismicity, and Soils


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Summary of Project Impacts 1

IMPACT TOPIC GC EC SBI SBE SBR PBL SUB CY RD HWY

A. Seismic Hazards

1. Potential hazards to structures and human safety due to seismic shaking

Applies to project as a whole

2. Potential hazards to structures and human safety due to liquefaction — — — — — — — — —

B. Landslides and Slope Stability

1. Potential hazards to structures and human safety due to landslides / slope instability

— — — — — —

C. Erosion

1. Erosion from grading/excavation Applies to project as a whole

D. Soils Constraints

1. Potential damage to structures due to expansive soils Applies to project as a whole

2. Potential excavation wall failure and drainage problems from construction of underground parking

— — — — — — — —

3. Potential uneven settlement in areas of unconsolidated fill — — — — — —

E. Hazardous Materials

1. Potential exposure to materials at Corporation Yard fill area — — — — — — — — —

= Significant Unavoidable Impact

= Significant Impact that can be Mitigated to Less-than-Significant

= Less than Significant Impact

— = No Impact or Not Applicable to the development site

GC – Golf Course; EC – Equestrian Center; SBI – Inn at Spanish Bay; SBE – Spanish Bay Employee Housing; SBR – Spanish Bay Driving Range; PBL – The Lodge at Pebble Beach; SUB – Residential Subdivisions; CY – Corporation Yard Employee Housing; RD – Roadway Improvements; HWY – Highway 1/Highway 68/17-Mile Drive Improvement

2

Relevant Project Characteristics 3

The Proposed Project includes new development at 13 sites including a new 18-4 hole golf course, a new driving range, new visitor-accommodating structures at 5 the Inn at Spanish Bay and the Lodge at Pebble Beach, reconstruction of the 6 existing Equestrian Center at the Sawmill site; construction of 60 employee 7 housing units near Spanish Bay and in the Corporation Yard, internal road 8 improvements, and improvements to the Highway 1/68 interchange. The project 9 would also create 33 residential lots within 5 subdivisions on which single-family 10 homes would be constructed in the future. 11



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The project will involve excavation of approximately 512,000 cubic yards, most 1 of which will be at the Proposed Golf Course location. Other areas of major 2 excavation (>20,000 cubic yards) include the underground parking lot sites at the 3 Inn at Spanish Bay and The Lodge at Pebble Beach, as well as at the New 4 Equestrian Center and Corporation Yard Employee Housing sites. Table 2.0-6 in 5 Chapter 2, “Project Description” identifies the cut and fill amounts by location. 6

Grading will be conducted at nearly all project locations. Areas of major grading 7 include the Proposed Golf Course, the New Equestrian Center, and Spanish Bay 8 Driving Range. 9

New structures will be built at the Proposed Golf Course, the New Equestrian 10 Center, the Spanish Bay Driving Range, the Spanish Bay Employee Housing, the 11 Inn at Spanish Bay, the Lodge at Pebble Beach, and the Corporation Yard. Future 12 residential structures would be built at the 5 subdivision locations. 13

Impacts and Mitigation Measures 14

Criteria for Determining Significance 15

In accordance with CEQA, State CEQA Guidelines, Monterey County plans and 16 policies, and agency and professional standards, a project impact would be 17 considered significant if the project would: 18

A. Seismic Hazards 19

Expose people or structures to potential substantial adverse effects resulting 20 from the rupture of a known earthquake fault, seismic ground shaking, 21 landslides, or seismic-related ground-failure, including liquefaction, and that 22 cannot be mitigated through the use of standard engineering design 23 techniques. 24

B. Landslides and Slope Stability 25

Be located on a geologic unit or soil that is unstable or that would become 26 unstable as a result of the project and potentially result in an onsite or offsite 27 landslide or slope failure. 28

Be located on an existing slope with a gradient greater than 30% 29

C. Erosion 30

Result in substantial soil erosion or the loss of topsoil and subsequent 31 sedimentation into local drainage facilities and water bodies. 32



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D. Soil Constraints 1

Be located on an expansive soil, as defined by the California Building Code 2 (1997) or be subject or to other soil constraints that might result in 3 deformation of foundations or damage to structures, creating substantial risks 4 to life or property. 5

E. Hazardous Materials 6

Create a significant hazard to the public or the environment through the 7 release of hazardous materials into the environment 8

Impacts and Mitigation Measures 9

A. Seismic Hazards 10

Impact GSS-A1. Placement of new structures could result in potential 11 structural damage and associated human safety hazards resulting from 12 ground shaking caused by earthquakes on nearby active and potentially 13 active faults. This is a significant impact that can be mitigated to a less-14 than-significant level for all new structures proposed by the project. 15

Recent regional and site-specific seismic hazard assessments on the Monterey 16 Peninsula indicate that the proposed development sites will likely experience 17 strong to severe ground shaking from an earthquake during the next 50 years 18 (Haro, Kasunich and Associates 2001a through e, 2002a and b; Monterey County 19 2002 Nielsen and Associates 2002a through i). Ground shaking could cause 20 damage to project-related structures and expose people using or inhabiting these 21 structures to adverse effects, such as injury or death. This is considered a 22 potentially significant impact but would be reduced to less-than-significant with 23 implementation of the following mitigation measure. 24

Mitigation Measure GSS-A1. Design all proposed structures in 25 accordance with the requirements of the California Building Code, 26 current edition, and recommendations contained in site-specific 27 geologic and geotechnical reports. To reduce the potential for structural 28 damage from ground shaking to acceptable levels, the applicant will 29 assure that all proposed structures are designed in accordance with the 30 most current and appropriate California Building Code standards and 31 with any additional recommendations made by the engineer of record 32 during the final stages of project design. 33

Impact GSS-A2. Placement of new structures at the New Equestrian Center 34 could result in potential structural damage and associated human safety 35 hazards from liquefaction caused by earthquakes on nearby, active and 36 potentially active faults. This is a significant impact that can be mitigated to 37 a less-than-significant level. 38



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The site-specific geologic investigation report prepared by Nielsen and 1 Associates (2002c) indicates that there is a moderate to high potential for 2 liquefaction to occur in the fill material present at the New Equestrian Center 3 development site. Liquefaction and associated ground failures could cause 4 damage to project-related structures and expose people using or inhabiting these 5 structures to adverse effects, such as injury or death. This is considered a 6 potentially significant impact but would be reduced to less-than-significant with 7 implementation of the following mitigation measure. 8

Mitigation Measure GSS-A2: Conduct further geotechnical 9 investigations at the New Equestrian Center and design all proposed 10 structures in accordance with the requirements of the California 11 Building Code, current edition, and recommendations contained in 12 site-specific geologic and geotechnical reports. The applicant will 13 conduct additional geotechnical evaluations of the unengineered fill 14 materials underlying Proposed Project structures and use the information 15 collected during these investigations as a basis for final grading, site 16 preparation, and foundation design. All proposed foundations will be 17 designed in accordance with the most current and appropriate California 18 Building Code standards, and with any additional recommendations 19 made by the engineer of record during the final stages of project design, 20 to minimize the potential for structural damage from liquefaction and 21 related ground failures. 22

B. Landslides and Slope Stability 23

Impact GSS-B1. Placement of buildings and grading on steep and/or 24 unstable slopes could result in potential structural damage and associated 25 human safety hazards from mass movements (landslides and debris flow). 26 This is a significant impact that can be mitigated to a less-than-significant 27 level. 28

Two lots in the proposed subdivision areas (Lot 1 in Area F-3 and Lot 5 in Area 29 PQR contain areas of slopes greater than 30%. There are also steep slopes at or 30 near the proposed locations of several of the golf cottages at the Proposed Golf 31 Course and in the area proposed for several of the Corporate Yard Employee 32 Housing buildings. The steep slopes at the Proposed Golf Course appear to be 33 associated with a small ravine and the excavated Spyglass pit. The slopes at the 34 Corporate Yard location are manufactured slopes from quarrying activity. While 35 the New Equestrian Center location also contains slopes greater than 30 percent, 36 based on the applicant’s plans, it appears that buildings will not be placed in the 37 areas of such steep slopes. There are also steep side slopes at the Highway 1/68 38 location, but these are not identified as a construction constraint in the 39 geotechnical report (Parikh 2001). 40

The DMF CIP prohibits development on slopes exceeding 30 percent unless 41 waived by the Director of Planning when: 42



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there is no alternative which would allow development to occur on slopes of 1 less than 30%; or 2

the proposed development better achieves the resource protection objectives 3 and policies of the Del Monte forest Land Use Plan and development 4 standards of the CIP. 5

The slopes at the two residential lots can be avoided through proper site design 6 and/or dedication of conservation easements, while allowing for residential 7 development on portions of the lots with less steep slopes. 8

Given the multiple environmental and physical constraints at the Proposed Golf 9 Course location, movement of the golf cottages from their proposed location to 10 another portion of the development area is not considered feasible without likely 11 resulting in additional environmental impact. An earlier (1996) geotechnical 12 investigation identified some slope stability concerns in the vicinity of the 13 proposed cottage locations due to steep, potentially unstable, man-made fill 14 slopes and incised dune slopes but noted that grading of the slopes could 15 eliminate potential instability (Haro, Kasunich, and Associates 1996a). From the 16 current (2002) grading plans and the geologic and geotechnical reports, it appears 17 that there is a small ravine near five of the proposed golf cottages that will be 18 filled and graded to accommodate construction of the cottages. The recent (2001) 19 geotechnical/geologic feasibility assessment did not identify the existing steep 20 slopes as a hazard that would preclude development of the cottages, although 21 certain recommendations were made relevant to cottage construction such as 22 control of surface and subsurface drainage, removal of unconsolidated fill and 23 use of engineered fill (Haro, Kasunich and Associates, 2001d). The recent 24 geologic investigation (2002) also recommended removal of any unengineered 25 fill and use of engineered compacted fill to properly support structures and 26 development of an engineered drainage and erosion control plan (Nielsen and 27 Associates 2002d). 28

Given that the slopes at the Corporate Yard location are manufactured slopes and 29 the available development area outside of the Corporate Yard itself is limited, it 30 is not considered feasible to move the Corporate Yard employee housing to 31 another location without resulting in additional environmental impact. The 32 geotechnical/geologic feasibility assessment identified slope instability within 33 old landfill slopes at the Corporate Yard as a concern that could be mitigated 34 through removal of unconsolidated fill, use of engineered fill proper grading; 35 and use of appropriate engineered foundations designed to accommodate soil 36 conditions (Haro, Kasunich, and Associates 2001g). 37

The proposed development activities would also involve a substantial amount of 38 land grading, which could destabilize existing slopes and create unstable 39 manufactured (cut-and-fill slopes) slopes. In particular, the applicant’s plans call 40 for creating slopes greater than 30% at the Proposed Golf Course and at the New 41 Equestrian Center. Resulting slope failures (e.g. landslides and debris flows) 42 could cause damage to existing and proposed structures and expose people to 43 resultant risk. 44

Potential construction and placement of structures on steep slopes and 45 manufacture of steep slopes are considered significant impacts that can be 46



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mitigated to a less-than-significant level with implementation of the following 1 mitigation measures. 2

Mitigation Measure GSS-B1-1. Revise tentative maps to exclude all 3 portions of residential lots in Area F-3 and Area PQR with slopes 4 greater than 30% from residential subdivision and dedicate 5 conservation easements for these areas. The tentative maps shall be 6 revised to exclude these steep slope areas from residential subdivision. 7 These areas shall be incorporated into the adjacent proposed preservation 8 and conservation areas. Residential development plans will be reviewed 9 for compliance by Monterey County planning staff. 10

Mitigation Measure GSS-B1-2. Implement recommended design 11 criteria of the Geotechnical Engineer of Record at the Proposed Golf 12 Course and Corporation Yard Employee Housing sites where 13 structures are proposed in areas of steep slopes or slope instability. 14 The applicant shall implement the recommended design criteria of the 15 geotechnical engineer of record during the final design and construction 16 of the proposed developments. All design criteria shall be in 17 conformance with the standards of the California Building Code and all 18 other applicable, county and local building code standards. 19

The following specific recommendations in the existing geotechnical 20 reports for the golf cottages and the Corporation Yard employee housing 21 shall also apply: 22

Golf Cottages - grading to ensure adequate removal of unsuitable fill 23 materials, proper placement of engineered fills beneath proposed 24 building sites, uniform bearing support for foundations and adequate 25 surface and subsurface drainage during and after construction (Haro, 26 Kasunich, and Associates, 2001d; Nielsen and Associates 2002d). 27

Corporation Yard - grading to endure adequate removal of unsuitable 28 fill materials and proper placement of engineered fills beneath 29 proposed building sites, uniform bearing support for the proposed 30 structures and adequate surface and subsurface site drainage during 31 and after construction (Haro, Kasunich, and Associates, 2001g). 32

These criteria may be refined and or new ones added during final stages 33 of project design and construction. 34

Mitigation Measure GSS-B1-3. Implement recommended design 35 criteria of the Geotechnical Engineer of Record at the Proposed Golf 36 Course and New Equestrian Center where steep slopes would be 37 manufactured. The applicant shall implement the recommended design 38 criteria of the geotechnical engineer of record during the final design and 39 construction of the proposed developments. All design criteria shall be in 40 conformance with the standards of the California Building Code and all 41 other applicable, county and local building code standards. 42



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The following specific recommendations in the existing geotechnical 1 reports for the Proposed Golf Course and the New Equestrian Center 2 shall also apply: 3

Golf Cottages - permanent fill slope gradients be no steeper than 2:1 4 (h:v) and permanent cut slopes should be no steeper than 1 to 1.5:1 5 (h:v) in terrace deposits and bedrock materials and 2.5:1 (h:v) in 6 sand dune deposits (provided seepage or groundwater is not observed 7 in the cuts) (Haro, Kasunich, and Associates, 1996a). 8

Corporation Yard - permanent fill slope gradients be no steeper than 9 2:1 (h:v); permanent cut slopes that expose dune sand or terrace 10 deposit should have a maximum slope gradient of 2:1 (h:v); pan 11 permanent cut slopes that expose granite or sandstone bedrock 12 should have a maximum slope gradient of 1.5:1 (h:v) provided 13 seepage or groundwater is not observed in the cuts. (Haro, Kasunich, 14 and Associates, 1996b). 15

If seepage or groundwater is observed within cut or fill slopes, additional 16 measures from the geotechnical engineer of record will be necessary. 17 Slopes with the recommended gradients may require periodic 18 maintenance to remove minor soils sloughing and erosion. These criteria 19 may be refined and or new ones added during final stages of project 20 design and construction. 21

C. Erosion 22

Impact GSS-C1. Grading and excavation could result in substantial soil 23 erosion, loss of topsoil, and sedimentation. This is a significant impact that 24 can be mitigated to a less-than-significant level. 25

According to Cook (1978), the hazard of water and wind erosion at the proposed 26 development sites ranges from moderate to very high. Construction of the 27 proposed developments would involve land clearing, land grading, and other 28 ground-disturbing activities that could temporarily increase soil erosion rates 29 during and shortly after project construction. Areas of substantial excavation (> 30 20,000 cubic yards) include the Proposed Golf Course, The Inn at Spanish Bay, 31 the Corporation Yard Employee, The Lodge at Pebble Beach, and the New 32 Equestrian Center. Areas of major grading (> 5 acres) include the Proposed Golf 33 Course, the New Equestrian Center, the Spanish Bay Driving Range, and the 34 Corporation Yard Employee housing. Construction-related erosion could result in 35 the loss of a substantial amount of nonrenewable topsoil and could adversely 36 affect water quality in nearby surface waters. This is considered to be a 37 potentially significant impact but would be reduced to less-than-significant with 38 implementation of the following mitigation measures. 39

Mitigation Measure GSS-C1-1. Prepare and Implement an Erosion 40 and Sediment Control Plan. The applicant, or a qualified consultant 41 acting on behalf of the applicant, will prepare and implement an erosion 42 and sediment control plan(s) for the proposed development activities. 43



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The plan will be prepared in accordance with the requirements of the 1 local erosion and sediment control ordinances. The plan will contain 2 details and specifications for a variety of standard and site-specific BMPs 3 that will be implemented to control wind and water erosion, stormwater 4 runoff, sediment, and other construction-related pollutants during project 5 construction. The erosion and sediment control plan will remain in effect 6 until all areas disturbed during construction have been permanently 7 stabilized. Many of the erosion and sediment control BMPs that will be 8 used during project construction are described in the BMP plan (Questa 9 2003). Additional measures may be prescribed during the final stages of 10 project design and construction. The Erosion and Sediment Control Plan 11 for each portion of the Proposed Project shall be submitted to Monterey 12 County Planning and Building Inspection Department for review and 13 approval prior to issuance of any grading permit for that portion of the 14 Proposed Project. This measure can be combined with requirements of 15 Mitigation Measure HWQ-C6 (see Chapter 3.4, “Hydrology and Water 16 Quality”) to prepare a SWPPP in compliance with NPDES general 17 construction permit requirements. 18

Mitigation Measure GSS-C1-2. Wet season grading additional 19 erosion control measures. The Erosion and Sediment Control Plan shall 20 also include additional erosion control measures, as required by the 21 Monterey County Erosion Control Ordinance (Section 16.12.090), such 22 as use of mulching, construction of sediment catch basins and cessation 23 of operations when soils are saturated and other measures as needed to 24 control erosion. 25

D. Soil Constraints 26

Impact GSS-D1. Construction in areas of expansive soils could result in 27 substantial damage to overlying building foundations and roadways. This is 28 considered a significant impact that can be mitigated to a less-than-29 significant level. 30

All of the proposed development sites contain at least one soil map unit that 31 contains expansive soil at some depth. If these expansive soil materials are 32 exposed at finished grade, they could cause substantial damage to overlying 33 building foundations and roadways. This is considered a potentially significant 34 impact but would be reduced to less-than-significant with implementation of the 35 following mitigation measure. 36

Mitigation Measure GSS-D1. Design all proposed structures in 37 accordance with the requirements of the California Building Code, 38 current edition and recommendations contained in site-specific 39 geologic and geotechnical reports. To minimize the potential for 40 damage from expansive soils, the applicant will assure that all proposed 41 structures are designed in accordance with the most current and 42 appropriate California Building Code standards and with any additional 43



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recommendations made by the engineer of record during the final stages 1 of project design. 2

Impact GSS-D2. Construction of underground structures in the presence of 3 shallow groundwater and weak surrounding deposits could result in 4 inadequate drainage and structural failure during construction or 5 operation. This is a significant impact that can be mitigated to a less-than-6 significant level. 7

The underground parking structures at the Lodge at Pebble Beach and the Inn at 8 Spanish Bay would be excavated into areas with shallow groundwater. Thus 9 excavation will likely result in significant seepage. Deep subdrains may not be 10 able to disperse subsurface flow via gravity. The terrace deposits and buried 11 alluvium at the Lodge underground parking structure location and the highly 12 fractured granodiorite at the Inn underground parking structure location are 13 potentially unstable. This is considered a significant impact but would be reduced 14 to less-than-significant with implementation of the following mitigation measure. 15

Mitigation Measure GSS-D2. Dewater excavations and shore 16 temporary cuts during construction of the underground parking 17 structures at the Inn and Lodge. Develop and implement an 18 engineered drainage plan to handle surface and subsurface runoff. 19 Implement all other relevant recommendations of the geotechnical 20 engineer of record. To minimize the potential for instability during 21 construction, the applicant shall require dewatering and shoring as 22 necessary to handle drainage and potential excavation wall stability. An 23 engineered drainage plan shall be developed to handle surface and 24 subsurface runoff for the underground parking structures; pumping 25 and/or design of subterranean retaining walls for undrained conditions 26 will be required. All other relevant recommendation of the geotechnical 27 and geologic reports for the underground parking structures shall be 28 implemented. (Haro, Kasunich, and Associates 2002a, 2001e; Nielsen 29 and Associates 2002b; 2002i). 30

Impact GSS-D3. Construction in areas of unconsolidated fill could result in 31 settlement and substantial damage to overlying building foundations. This is 32 a significant impact that can be mitigated to a less-than-significant level. 33

The New Equestrian Center, the Corporate Yard Employee Housing, the golf 34 cottage site at the Proposed Golf Course location, and the Spanish Bay Employee 35 Housing area contain areas of unconsolidated fill. Placement of structures in 36 these areas could result in uneven settlement that could cause substantial damage 37 to overlying building foundations. This is considered a potentially significant 38 impact but would be reduced to less-than-significant with implementation of the 39 following mitigation measure. 40

Mitigation Measure GSS-D3. Design all proposed structures in 41 accordance with the requirements of the California Building Code, 42 current edition and implement recommendations of project 43 geotechnical and geologic reports. All structures within areas of 44



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unconsolidated fill shall be built in accordance with the UBC and all 1 relevant recommendations in the geotechnical and geologic reports 2 relevant to unconsolidated fill shall be incorporated into design and 3 construction, including the following: 4

Corporate Yard - complete removal of the existing landfill materials 5 and reclamation of the dump site with imported engineering fill 6 placed in accordance with report recommendations and 7 subexcavation and redensification of unengineeered fill to provide 8 support for foundations placed outside of the limits of the landfill 9 (Haro Kasunich and Associates 2001f). 10

New Equestrian Center - use of conventional spread footing 11 foundations systems provided the footings penetrate loose soil and 12 are embedded into firm native soil or underlain by engineered fill; 13 removal of fill where feasible; use of pier and grade beam foundation 14 penetrating the fill where removal of fill is not feasible (Haro 15 Kasunich and Associates 2001g) 16

Golf Cottages – removal of unengineered fill beneath any of the 17 proposed cottages and replacement with engineered, compacted fill 18 to properly support structures (Nielsen and Associates 2002d). 19

Spanish Bay Employee Housing - removal of fill materials from 20 affected building sites and recompaction as engineered fill if they are 21 used for support of footings, concrete slabs-on-grade, pavements or 22 exterior improvements; complete removal of organically-23 contaminated materials due to buried marine animals and 24 replacement with clean import or native soil (Haro, Kasunich and 25 Associates 2002b). 26

E. Hazardous Materials 27

Impact GSS-E1. Potential hazardous materials and methane off-gassing 28 related to materials in the fill at the Corporation Yard may result in worker 29 and/or resident exposure to hazardous materials or hazardous conditions. 30 This is a significant impact that can be mitigated to a less-than-significant 31 level. 32

While the Phase 1 conducted by D & M Consulting Engineers (DMCE) (DMCE 33 1999) did not identify any evidence of hazardous material being dumped in the 34 area, the area is identified as an unsupervised dumping ground. Thus, there is a 35 potential for hazardous material to have been placed in the fill, perhaps without 36 the knowledge of operating personnel. In addition, DMCE identified a potential 37 for methane off-gassing from the fill. Workers and/or future residents could be 38 exposed to hazardous material, if present in the fill area. Methane off-gassing 39 could also result in an a hazardous condition for workers and/or future residents. 40 This is a potentially significant impact that can be reduced to less-than-41 significant with implementation of the following mitigation measures. 42



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Mitigation Measure GSS-E1-1. Conduct Phase II investigation 1 consisting of subsurface soil borings, collect samples for analysis of 2 hazardous constituents that may be present in the fill, submit results 3 to Monterey County Health Department (MCHD) and Department 4 of Toxic Substances Control (DTSC); initiate remedial action if 5 warranted to protect workers during construction or future 6 residents in accordance with applicable local, state, and federal 7 regulations. In order to prevent potential worker and/or resident 8 exposure to potential hazardous materials that may have been placed in 9 the Corporation Yard fill area, the applicant shall conduct a subsurface 10 soil investigation, including analytical testing of subsurface soil samples 11 from within the fill for the presence of hazardous constituents. The 12 sampling results shall be provided to Monterey County Department of 13 Environmental Health and the California Department of Toxic 14 Substances Control. If warranted based on the results, the applicant shall 15 remediate the site as necessary to prevent significant exposure of workers 16 and/or future residents to hazardous constituents, if found. Remedial 17 action, if warranted, shall be conducted in compliance with all applicable 18 local, state, and federal regulations regarding hazardous material and 19 hazardous waste. Remedial action, if warranted, shall be completed prior 20 to construction of the employee housing area. 21

Mitigation Measure GSS-E1-2. Assess potential for methane off-22 gassing at the Corporation Yard fill area; submit results to MCDH; 23 incorporate into construction plans and final design methane 24 controls and/or venting as necessary to avoid hazardous conditions. 25 In order to prevent hazardous conditions (e.g., explosion, asphyxiation), 26 the applicant shall assess the potential for methane off-gassing (including 27 collection of soil gas samples) to result in unsafe conditions for workers 28 during construction and/or future residents. The assessment shall be 29 provided to Monterey County Department of Environmental Health. If 30 warranted based on the assessment, the applicant shall incorporate 31 methane control measures (such as geomembranes) and/or venting in 32 design plans for employee housing as necessary to avert hazardous 33 conditions. Monitoring of methane shall be conducted post-construction, 34 if determined necessary by the County to confirm the effectiveness of 35 any implemented control measures. Design changes shall be included in 36 final engineering plans submitted to County prior to issuance of grading 37 permit. 38

Environmental Setting 39

Geology 40

The Proposed Project area is located in the Coast Ranges geomorphic province of 41 California, near the northern terminus of the Santa Lucia Range. The most recent 42 and large-scale geologic map of the Monterey Peninsula (Clark et al. 1997) 43 indicates that there are 9 surficial geologic units located within the project area 44



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and vicinity. The general characteristics of these units, and the development sites 1 affected by each, are described in Table 3.2-1. 2

Seismicity 3

Area Faults 4

The California State Geology and Mining Board (the Board) has established 5 policies and criteria for the classification of known faults in California based on 6 the presence or absence of a detectable fault trace and the recency of fault 7 displacement (Hart and Bryant 1997). Detectable fault traces that show evidence 8 of displacement during the last 10,000 to 11,000 years (i.e., Holocene faults) are 9 defined as active and are considered to have the greatest potential for surface 10 rupture. Detectable fault traces that show evidence of displacement between 11 10,000 and 1.6 million years ago (i.e., Quaternary faults) are defined as 12 potentially active, and are considered to have less potential for surface rupture. 13 The Board has not established an official category for faults that show no 14 evidence of displacement during the last 1.6 million years (i.e., pre-Quaternary 15 faults). Although such faults are not deemed “inactive,” they are considered to 16 have a relatively low potential for surface rupture. 17

The Del Monte Forest is located within a highly seismically active region of 18 California. The fault activity map of California (Jennings 1994) and recent 19 geologic investigations conducted by Nielsen and Associates (2002a-i) indicate 20 that the project area is located in the vicinity of several active and potentially 21 active faults/fault zones. The names of these faults/fault zones, the recency of 22 their activity, and their approximate distance from the project area are listed 23 below. 24

Active Faults 25

San Andreas Fault: located ~28 miles from the Del Monte Forest 26

Argent Fault: located ~31 miles from the Del Monte Forest 27

Palo Colorado-San Gregorio Fault: located ~ 4 miles from the Del Monte 28 Forest 29

Calaveras/Paicines/Hayward Fault: located ~35 miles from the Del Monte 30 Forest 31

Monterey Bay Fault: located ~4 miles from the Del Monte Forest 32

Sylvan Thrust Fault: located ~ 0.5 mile from the Del Monte Forest 33

Hatton Canyon Fault: located ~1000 feet from the Del Monte Forest 34

Table 3.2-1 Geologic Units Within Project Development Areas

Geologic Unit Geologic Period Description Development Areas

Artificial fill Holocene Artificial fill in the project area consists of a heterogeneous mixture of artificially deposited material ranging from well-compacted sand and silt to poorly compacted sediment high in organic matter content.

Residential Subdivisions

Dune sand deposits Holocene Dune sand deposits in the project area consist of unconsolidated, well-sorted, medium- to coarse-grained sand as much as 80 ft thick.

Proposed Golf Course Spanish Bay Resort

Undivided alluvial deposits Holocene The undivided alluvial deposits that occur within the project area consist of unconsolidated, heterogeneous, moderately-sorted silt and sand with discontinuous lenses of clay and silty clay. The thickness of these deposits is highly variable but may be as much as 100 feet.

New Equestrian Center Residential Subdivisions

Young dune deposits Pleistocene The young dune deposits that occur within the project area consist of weakly-consolidated, well-sorted, fine- to medium-grained sand. The thickness of these dune deposits ranges from 6.5 to 80 feet.

Spanish Bay Resort Spanish Bay Driving Range Spanish Bay Employee Housing

Older dune deposits Pleistocene The older dune deposits that occur within the project area consist of weakly- to moderately-consolidated, moderately well-sorted silt and sand. The thickness of these dune deposits ranges from 6.5 to 80 feet.

Proposed Golf Course New Equestrian Center

Coastal terrace deposits Pleistocene The coastal terrace deposits that occur within the project area consist of semiconsolidated, moderately well-sorted marine sand containing thin, discontinuous gravel-rich layers. The terrace deposits are locally overlain by poorly-sorted fluvial and colluvial silt, sand, and gravel. The thickness of coastal terrace deposits in the project area is variable, but is generally less than 20 feet.

Proposed Golf Course New Equestrian Center Lodge at Pebble Beach Residential Subdivisions

Lower unit of the Monterey Formation

Miocene The lower unit of the Monterey Formation consists of thin-bedded, yellowish-brown, semi-siliceous mudstone that is as much as 100 feet thick.

Residential Subdivisions Highway 1/68

Unnamed sandstone Miocene The unnamed sandstone units in the project area typically consist of dark-yellowish-orange, very thick bedded, coarse- to fine-grained, angular to subangular, poorly to well-sorted arkosic sandstone, with common very thick cobble-boulder conglomerate beds in the lower part and rare siltstone beds in the upper part (Clark et al. 1997).


Porphyritic granodiorite of Monterey of Ross (1976)

Cretaceous The porphyritic granodiorite of Monterey of Ross (1976) is light gray to moderate pink and medium-grained.




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Potentially Active Faults 1

Reliz (King City) Fault: located ~10 miles from the Del Monte Forest 2

Cypress Point Fault: located beneath the extreme southwestern part of the 3 Del Monte Forest 4

Zayante-Vergeles Fault: located ~25 miles from the Del Monte Forest 5

Navy Fault: located ~3 miles from the Del Monte Forest 6

Seaside Fault: located ~4 miles from the Del Monte Forest 7

Ord Terrace Fault: located ~5 miles from the Del Monte Forest 8

Chupines Fault: located ~5 miles from the Del Monte Forest 9

Tularcitos Fault: located ~8 miles from the Del Monte Forest 10

Sur-Nacimiento Fault: located ~5 miles from the Del Monte Forest 11

The Cypress Point fault trends northwest across the tip of the Monterey Peninsula 12 from Pescadero Point to Fan Shell Beach and is concealed beneath Quarternary 13 sediments. Terrace deposits do not appear to be displaced by the Cypress Point 14 faults, suggesting that fault movement occurred before the Quartenary period 15 (EIP 1995). 16

Seismic Hazards 17

Seismic hazards present in Monterey County include ground rupture along faults, 18 ground shaking, and liquefaction (Monterey County 2002). Each of these hazards 19 and their potential to affect the proposed development sites are discussed below. 20 Slope stability and landslides are discussed separately below. 21

Surface Fault Rupture 22

Surface fault rupture is a seismic hazard that can damage structures constructed 23 above active faults. Surface fault rupture can occur rapidly during an earthquake 24 or slowly over many years via a process known as fault creep. None of the 25 proposed development sites are located above or in the immediate vicinity of the 26 active or potentially active faults identified by Jennings (1994) and Nielsen and 27 Associates (2002). The Cypress Point fault is the closest of the active or 28 potentially active faults in the vicinity of the Proposed Project. This fault is a 29 northwest-trending oblique-slip fault located approximately 2,000 to 2,500 feet 30 southwest of the proposed facilities at The Lodge at Pebble Beach and the 31 Proposed Golf Course. According to the geologic investigations conducted by 32 Nielsen and Associates (2002a-i) the Cypress Point fault is probably capable of 33 generating earthquakes in the 4–5 Magnitude range. Accordingly, the surface 34 fault rupture hazard at the proposed development sites is very low. 35



3.2-15

February 2004

Seismic Ground Shaking 1

Seismic ground shaking can cause varying degrees of damage to buildings, 2 ranging from cosmetic to severe structural damage. In 1996, California Division 3 of Mines and Geology (CDMG) released a probabilistic seismic hazard 4 assessment for the state of California to aid in the assessment of seismic ground 5 shaking hazards in California (Peterson et al. 1996). The report contains a 6 probabilistic seismic hazard map that depicts the peak horizontal ground 7 acceleration values exceeded in a given region of California at a 10% probability 8 in 50 years (i.e., a 0.2% probability in one year). 9

The peak horizontal ground acceleration values depicted on the map represent 10 probabilistic estimates of the ground-shaking intensity likely to occur in different 11 regions of California as a result of characteristic earthquake events on active and 12 potentially active faults in California, and can be used to assess the relative 13 seismic ground-shaking hazard for a given region. The probabilistic peak 14 horizontal ground acceleration values for the project area (i.e., the Monterey 15 peninsula) range from strong (0.3g) to severe (0.6g) (where g is equal to the 16 acceleration due to gravity), suggesting that the development sites will likely 17 experience strong to severe ground shaking from an earthquake in the next 18 50 years. The ground acceleration values and general ground-shaking hazard 19 reported by Peterson et al. (1996) are consistent with those reported by Monterey 20 County (2002), Haro, Kasunich and Associates (2001a-e), Haro, Kasunich and 21 Associates (2002a and b), Nielsen and Associates (2002a through i), and Parikh 22 Consultants (2001). 23

All development sites could be potentially affected by seismic ground shaking. 24

Liquefaction and Related Ground Failures 25

Liquefaction is a process by which soils and sediments lose shear strength and 26 fail during episodes of intense ground shaking. Liquefaction and related ground 27 failures, such as lateral spreading, may damage pipelines and/or result in the loss 28 of foundation-bearing capacity for buildings, which can cause structures to settle, 29 tip, or rise through liquefied soils and sediments. 30

The susceptibility of a given soil or sediment to liquefaction is primarily a 31 function of local groundwater conditions and inherent soil/sediment properties 32 such as texture and bulk density. Poorly consolidated, well graded, and water-33 saturated fine sands and silts located within 50 feet of the surface are typically 34 considered to be the most susceptible to liquefaction. The liquefaction potential 35 map of Monterey County (Monterey County 2002) indicates that a high potential 36 for liquefaction exists only in areas underlain by dune sand deposits and 37 undivided alluvial deposits (described above). The Proposed Golf Course, the 38 New Equestrian Center, the Spanish Bay Resort, and Residential Subdivision 39 development sites are underlain by these types of deposits (Clark et al. 1997). 40 However, the only appreciable liquefaction hazard noted in the site-specific 41 geologic and geotechnical reports prepared for the proposed development sites 42



3.2-16

February 2004

was associated with unengineered fill encountered during subsurface 1 investigations at the New Equestrian Center (Nielsen and Associates 2002c). 2

Slope Stability and Landslides 3

The stability of existing (natural and manufactured) slopes in the proposed 4 development sites has been evaluated by several geologic and geotechnical 5 engineering firms. No slope stability hazards were identified at the New 6 Equestrian Center, Spanish Bay Resort, Lodge at Pebble Beach, Residential 7 Area F-2 and I-2, and the Highway 1/68 interchange (Haro, Kasunich and 8 Associates 2001a,b,c, and e, 2002a,b; Nielsen and Associates 2002a-i; Parikh 9 Consultants 2001; Terratech Inc. 1991). However, the potential for 10 landsliding/slope instability to occur was identified at the Proposed Golf Course, 11 proposed Residential Subdivisions F-3, K, and PQR, and the Corporate Yard 12 Employee Housing due to the steep slope gradients that occur in these areas 13 (Foxx, Nielsen & Associates 1990a,b; M. Jacobs & Associates 1990, 1991a,b; 14 Terratech Inc. 1991; Haro, Kasunich, and Associates 2001d, 2001f). 15

Topography in the proposed development sites is predominantly level to strongly 16 sloping (0 to 16% slopes). However, some of the proposed development sites 17 include steep slopes where gradients exceed 30%. These sites include the 18 Proposed Golf Course, the New Equestrian Center, two lots in the proposed 19 Residential Subdivisions (Lot 1 at Area F-3 and Lot 5 at Area PQR), the 20 Corporate Yard Employee Housing, and the Highway 1/68 interchange (PBC 21 2002, Parikh Consultants 2001). 22

Soils 23

Soils on the Monterey Peninsula were mapped by the U.S. Department of 24 Agriculture Soil Conservation Service during their survey of Monterey County 25 (Cook 1978). There are approximately 9 soil map units located in the proposed 26 development sites. Soil map unit characteristics and which sites contain different 27 soil units are summarized in Table 3.2-2. Some of the typical characteristics, 28 hazards, and constraints associated with the dominant soil series that comprise 29 the majority of these map units are summarized in Table 3.2-3. 30

Geotechnical Constraints and Concerns 31

Geotechnical constraints and concerns identified in the geotechnical reports 32 prepared for the Proposed Project are summarized in Tables 3.2-4 and 3.2-5. 33

Table 3.2-2. Soil Units Description for Soils found within Project Development Areas

Soil Unit Description Project Development Areas

Baywood Sand 2 to 15% Slopes

This map unit is dominated by soils of the Baywood series, which typically consists of very deep, somewhat excessively drained, coarse-textured soils formed from wind-blown (eolian) sand deposits on dunes.

Spanish Bay Resort Spanish Bay Driving Range Spanish Bay Employee Housing

Dune Land This map unit consists of gently sloping to steep areas of loose, excessively drained,

wind-deposited sand on hummocks, mounds, and hills. Proposed Golf Course Spanish Bay Resort

Narlon Loamy Fine Sand 2 to 9% Slopes

This map unit is dominated by soils of the Narlon series, which typically consists of deep, somewhat poorly drained, coarse- and fine-textured soils formed from soft marine sediments on uplands.

Proposed Golf Course New Equestrian Center Lodge at Pebble Beach Residential Subdivisions Highway 1/68

Narlon Loamy Fine Sand 15 to 30% Slopes

This map unit is dominated by soils of the Narlon series, which typically consist of deep, somewhat poorly drained, coarse- and fine-textured soils formed from soft marine sediments on uplands.


Pits and Dumps

This map unit consists of areas from which native soil and underlying material have been removed and areas of uneven accumulation of waste material. These areas include rock quarries, sand and gravel pits, and excavations for refuse disposal.

New Equestrian Center Corporation Yard Employee Housing

Santa Lucia Shaly Clay Loam 15 to 30% Slopes

This map unit is dominated by soils of the Santa Lucia series, which typically consist of shallow to moderately deep, well drained, moderately fine-textured soils formed from weathered shale.

Highway 1/68

Santa Lucia Shaly Clay Loam 30 to 50% Slopes

This map unit is dominated by soils of the Santa Lucia series, which typically consist of shallow to moderately deep, well drained, moderately fine-textured soils formed from weathered shale.

Highway 1/68

Sheridan Coarse Sandy Loam 15 to 30% Slopes

This map unit is dominated by soils of the Sheridan series, which typically consist of moderately deep to deep, well drained, moderately coarse-textured soils that formed from weathered granitic and schistose bedrock on hills and mountains.

Proposed Golf Course Lodge at Pebble Beach Residential Subdivisions

Tangair Fine Sand 2 to 9% Slopes

This map unit is dominated by soils of the Tangair series, which typically consist of very deep, somewhat poorly drained, coarse-textured soils formed from sand deposits on wind-modified terraces.

Proposed Golf Course Spanish Bay Resort Spanish Bay Driving Range, Spanish Bay Employee Housing

Table 3.2-3. Characteristics of Soil Map Units Located in the Project Area and Vicinity

Soil Map Unit Parent Material Texture

Depth to Bedrock (inches)

Shrink-Swell

Potential Runoff Rate

Water Erosion Hazard

Wind Erosion Hazard2

Development Sites with Soil

Unit

BbC Baywood sand, 2 to 15% slopes

eolian sand deposits

sand >60 low slow-medium

slight-moderate

high SBI, SBE, SBR

Df Dune Land eolian sand deposits

sand >60 low v. slow-slow

high-v. high high GC, SBR

NcC Narlon loamy fine sand,

2 to 9% slopes

soft marine sediments

loamy fine sand, clay

53 low-high slow-medium

moderate high GC, EC, PBL, SUB, HWY

NcE Narlon loamy fine sand,

15 to 30% slopes

soft marine sediments

loamy fine sand, clay

53 low-high medium moderate high SUB

Pm Pits and Dumps N/A variable variable variable variable high variable EC, CY SfE Santa Lucia shaly clay,

15 to 30% slopes weathered shale shaly clay loam 24 low medium moderate low HWY

SfF Santa Lucia shaly clay 30 to 50% slopes

weathered shale shaly clay loam <20 low rapid high low HWY

SoE Sheridan coarse sandy loam, 15 to 30%

slopes

weathered schistose and

granitic bedrock

coarse sandy loam

39 low rapid moderate high GC, PBL, SUB

TaC Tangair fine sand, 2 to 9% slopes

sand fine sand, sandy loam

>60 low slow slight high GC, SBI, SBE, SBR

1Properties listed are for the dominant soil map unit component(s) only. 2Wind erosion hazard estimated from Wind Erodibility Group (WEG) ratings (U.S. Department of Agriculture Natural Resources Conservation Service 2001) as determined by J&S as follows: WEGs 1 through 3 = high; WEGs 4 through 6 = moderate; WEGs 7 and 8 = low. N/A Not Applicable GC – Golf Course; EC – Equestrian Center; SBI – Inn at Spanish Bay; SBE – Spanish Bay Employee Housing; SBR – Spanish Bay Driving Range; PBL – The Lodge at Pebble Beach; SUB – Residential Subdivisions; CY – Corporation Yard Employee Housing; HWY – Highway 1/Highway 68/17-Mile Drive Improvement Source: (Cook 1978)

Table 3.2-4. Summary of Geologic, Seismic, and Soil Constraints At Proposed Development Sites

Constraint Gol

f Cou

rse

Eque

stria

n C

ente

r

Span

ish

Bay

R

esor

t

Span

ish

Bay

Em

ploy

ee

Hou

sing

Span

ish

Bay

D

rivin

g R

ange

Pebb

le B

each

Lo

dge

Res

iden

tial

Subd

ivis

ions

Cor

pora

te Y

ard

Empl

oyee

H

ousi

ng

Hw

y 1/

68

Impr

ovem

ents

Strong Seismic Ground Shaking X X X X X X X X X

High Liquefaction Potential X X X

Moderate Water Erosion Hazard X X X X

High Water Erosion Hazard X X X X X

High Wind Erosion Hazard X X X X X X X X X

Expansive Soils X X X X X X X X X

Unconsolidated Fill X X X X

Existing Steep Slopes (>30%) X X F-3, PQR X X

Slope Stability Hazards X F-3, PQR X

No major constraints with implementation of standard engineering methods; recommendations of Geotechnical Engineer of Record; and CIP, zoning, and UBC standards.

X X X X X X X X X

Summary based on sources listed in Table 3.2-5

Table 3.2-5. Summary of Hazards and Concerns mentioned in Geotechnical and Geologic Reports Project Development Area Hazards and Concerns Mentioned

Proposed Golf Course No adverse geotechnical or geologic hazards that would preclude the development of the Proposed Golf Course and associated structures.

Site-specific concerns include:

Golf Course: providing secure and uniform support for the proposed structure foundations, redensifing or removing existing fill from building and parking lot areas, providing adequate surface and subsurface site drainage and the potential for strong seismic shaking

Golf Cottages: strong seismic shaking, extensive grading to ensure adequate removal of unsuitable fill materials, proper placement of engineered fills beneath proposed building sites, uniform bearing support for foundations and adequate surface and subsurface drainage during and after construction.

Golf Clubhouse: strong seismic shaking, high groundwater, adequate surface and subsurface site drainage during and after construction, presence of high groundwater, uniform bearing support for foundations, and stability of temporary cut slopes

Golf Course Restrooms: Proposed buildings may be constructed on conventional spread footings embedded into redensified, on-site native soil. Other concerns include the shallow perched groundwater table that occurs during the winter rain season; a thin layer of clay found about a foot below ground surface; and the wet, loose condition of the near-surface, foundation-zone soils.

New Equestrian Center No adverse geotechnical or geologic hazards that would preclude the development of the New Equestrian Center.

Concerns: uniform support for the proposed structure foundations, adequate surface site drainage, erosion potential, the potential for strong seismic shaking, mitigation of loose fill below proposed structures.; presence of gullying and shallow groundwater.

Spanish Bay Resort No adverse geotechnical or geologic hazards that would preclude the development of the Spanish Bay Resort

Concerns: strong seismic shaking, provision for adequate surface and subsurface site drainage during and after construction, firm and uniform bearing support for foundations, weak zone of granitic rock at proposed underground structure and stability of temporary cut slopes; and high groundwater conditions

Spanish Bay Driving Range

No adverse geotechnical or geologic hazards that would preclude the development of the Spanish Bay Driving Range.

Concerns: strong seismic shaking, controlled grading to ensure proper placement of engineered fills beneath the proposed building site and pavement sections, surface and subsurface site drainage during and after construction, and secure uniform bearing support for foundations.

Spanish Bay Employee Housing

No adverse geotechnical or geologic hazards that would preclude the development of the Spanish Bay Employee Housing

Concerns: strong seismic shaking, extensive grading to ensure adequate removal of unsuitable fill materials and proper placement of engineered fills beneath proposed building sites, surface and subsurface site drainage during and after construction, high groundwater; and secure, uniform bearing support for foundations.

Project Development Area Hazards and Concerns Mentioned

The Lodge at Pebble Beach

No adverse geotechnical or geologic hazards that would preclude the development of any project components at The Lodge at Pebble Beach.

Concerns for all sites include strong seismic shaking, firm and uniform bearing support for foundations, and provision for adequate surface and subsurface site drainage during and after construction. Site specific concerns include:

Underground Parking Structure: loose saturates subsurface zone and stability of temporary cut slopes, potential for significant groundwater;

Fairway One structure: potential for local weak subsurface zones and stability of temporary cut slopes, potential for significant groundwater.

Residential Subdivisions Note: No geotechnical or geologic reports submitted by applicant for subdivisions. Information based on prior EIR (EIP 1995) and site slope maps (PBC 2002).

No identified geo-seismic hazards or constraints that would preclude the development overall of the proposed residential subdivisions, with potential exception of landslide potential on portions of several lots (noted below).

Concerns for all sites: strong seismic shaking, stability of temporary cut slopes; expansive/weak soils, erosion potential.

Specific concern for Areas F-3, K, and PQR: potential for landsliding on areas with steep slopes.

Corporation Yard Employee Housing

No adverse hazards that would preclude the development of the Corporation Yard Employee Housing.

Concerns: strong seismic shaking, slope instability within the old landfill slopes, settlement of the existing landfill materials, extensive grading to endure adequate removal of unsuitable fill materials and proper placement of engineered fills beneath proposed building sites, uniform bearing support for the proposed structures and adequate surface and subsurface site drainage during and after construction.

Highway 1/68 No adverse geotechnical hazards identified that would preclude construction of the proposed roadway improvements

Source: Foxx, Nielsen and Associates 1990a, b; Haro, Kasunich and Associates 2001a–g, 2002a, b; M. Jacobs & Associates 1990, 1991a, b; Mark Thomas & Co. Inc. 2001; Nielsen and Associates 2002a–i; Terratech Inc. 1991; Parikh Consultants, 2001(for Highway 1/68); EIP 1995 (for residential areas).



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February 2004

Hazardous Materials 1

According to the Initial Study (see Appendix A), none of the proposed uses or 2 locations will result in creation of risks associated with hazardous material use, 3 creation of a health hazard, or interference with an emergency response plan 4 (Monterey County 2002b). Thus, operational and upset impacts related to 5 hazardous materials are not analyzed further in this DEIR. 6

The Corporation Yard has had past and current use of fuel underground storage 7 tanks. In addition, the Employee Housing site is the site of a former landfill. To 8 assess potential hazardous materials related to the existing and prior use of the 9 site, D & M Consulting Engineers completed a Phase 1 Environmental Site 10 Assessment for various Pebble Beach Company-owned properties including the 11 Corporation Yard in July 1999 (DMCE 1999). DMCE conducted an additional 12 site reconnaissance and environmental document review for the Corporation 13 Yard in 2002 (DMCE 2002). 14

Conclusions regarding the Corporation Yard in the Phase 1 report are as follows: 15

Underground Storage Tanks. Double-walled gasoline, diesel, and waste oil 16 USTs have been operated at the corporate yard since 1986. The MCHD 17 issued a 1998 upgrade compliance certificate for the UST systems, and leaks 18 have not been detected. Overfill protection or sump sensors were not 19 installed until 1997. The annular space sensors for all three USTs failed 20 function tests in October 1997; the monitoring system was later upgraded, 21 Two sumps are located in the corporation yard, one in the fueling area. Two 22 hydraulic hoists are operated at the yard, with underground piping leading to 23 an aboveground hydraulic oil tanks. DMCE did identify the tanks as a 24 recognized environmental condition, but did not identify any indications of 25 leaks from any of these systems and did not recommend further analytic 26 testing. DMCE did note that the operation of such systems should be 27 monitored closely (DMCE 1999). 28

Landfill. DMCE identified that a portion of the Del Monte quarry was used 29 as an unsupervised dumping ground for many years. During a prior 30 subsurface geotechnical investigation, debris encountered in the fill material 31 included wood chunks, decayed wood fragments, metal plastic, concrete, 32 asphalt and masonry; all inert debris. Based on the prior subsurface 33 investigation, a fill area was identified on the site, measuring up to 60 feet 34 thick. The fill material has a strong "fuel-type odor", but this was attributed 35 to decaying organic matter. DMCE identified that methane off-gassing may 36 also be occurring in this area. DMCE did not evidence that hazardous 37 materials were dumped in this area. DMCE identifies that there is an absence 38 of beneficial uses of ground water in this bedrock bowl. DMCE did not 39 identify the landfill as a recognized environmental condition and did not 40 recommend further analytical testing (DMCE 1999). 41

The 2002 site reconnaissance and records review did not identify any evidence of 42 stains, fuels or potentially hazardous materials at the area proposed for the 43 employee housing and did not identify any spills, contaminant, or leak files for 44 the Corporation Yard site on files at the MCHD (DMCE 2002). 45

46

Chapter 3.2 2 Geology, Seismicity, and Soils

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