4.5 GEOLOGY AND SOILS

4.5 Geology and Soils
AES 4.5-1 Crystal Geyser Bottling Plant Project January 2017 Draft Environmental Impact Report
4.5 GEOLOGY AND SOILS
4.5.1 INTRODUCTION
This section addresses the potential for the Proposed Project to impact the geology and soils in and
around the Proposed Project location. Following an overview of the environmental setting in Section
4.5.2 and the relevant regulatory setting in Section 4.5.3, project-related impacts and recommended
mitigation measures are presented in Section 4.5.4 and Section 4.5.5, respectively.
4.5.2 ENVIRONMENTAL SETTING
Regional Setting
The project site is located in the Cascade Range geomorphic province of California, which lies between
the Klamath Mountains and Sierra Modoc Plateau provinces north of the Sierra Nevada province in the
northernmost portion of California (CGS, 2002). The Cascade Range province is characterized by
volcanoes, in addition to being in a region of high seismic activity (USGS, 2014). This region is typically
underlain by lava and volcanic debris formed by thousands of small, short-lived volcanoes (NPS, 2014).
The Cascade Range first appeared in the late Eocene (36 million years ago [MYA]), with the major peaks
visible today created since the Pleistocene (1.6 MYA) (USGS, 2014).
Siskiyou County (County) is comprised of the Modoc Plateau and Klamath Mountains geomorphic
provinces in addition to the Cascade Range province (CGS, 2002). These provinces are similar to the
Cascade Range province, in that they are characterized by volcanic activity. The Modoc Plateau
province contains occasional lakes, marshes, and streams, as well as north-south faults. The Klamath
Mountains province is similar to the Sierra Nevada, with rugged topography and prominent peaks and
ridges reaching 6,000 to 8,000 feet above mean sea level (amsl).
The project site is located southwest of Mt. Shasta, which has erupted every 600 to 800 years in the past
10,000 years (USGS, 2012). The project site is located in an area predicted to have moderate mud flows
as a result of volcanic activity at Mt. Shasta and Shastina (City of Mt. Shasta, 2007).
Site Topography
Elevations at the project site range from approximately 3,640 to 3,800 feet amsl, with higher elevations to
the west towards Spring Hill and northeast towards Mt. Shasta (USGS, 2015). The central project site
was originally graded and developed during the construction of the water bottling facility (Plant) in 2000.
The elevation of the Plant was graded to be 30 feet lower than the elevation of Ski Village Drive to shield
views of the warehouse and other ancillary structures (Geosyntec, 2013). The surrounding topography is
characterized by similar terrain and elevation.
Regional Seismicity and Fault Zones
The Alquist-Priolo Act defines active faults as those that have shown seismic activity during the Holocene
period, approximately the past 11,000 years (DOC, 2016). According to the United States Geological
"
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Cedar Mountain fault system (Mount Hebron fault zone)
Cedar Mountain fault system, Cedar Mountain section (East Cedar Mountain fault)
unnamed fault
unnamed fault
Cedar Mountain fault system, Stephens Pass section (Stephens Pass fault)
Ash Creek fault
PROJECT SITE
23.64 Miles
6.73 Miles
SOURCE: USGS Earthquake Hazards Program, 7/26/2010; California Geological Survey, 2005; AES, 8/29/2016
Crystal Geyser Draft Environmental Impact Report / 216537
USGS FAULTS BY ERA <1,600,000 Quaternary <130,000 Quaternary <15,000 Latest Quaternary
LEGEND
approximately 4.6 miles west of the project site. Additional faults are located north and west of the project
site (USGS, 2016a). The Cedar Mountain fault system, approximately 23.6 miles west of the project site,
is the closest active fault to the site, last active in 1978 (Figure 4.5-1). According to the California
Geological Survey (CGS; CGS, 2015), the closest Alquist-Priolo fault is the Cedar Mountain section of the
Cedar Mountain fault system (see Figure 4.5-1).
Seismic Shaking Intensity
A common measure of earthquake intensity and effects due to ground shaking is the Modified Mercalli
Intensity (MMI) Scale. The range of MMI values and a description of intensity factors are displayed in
Table 4.5-1. The MMI values for intensity range from I to XII, with intensity descriptions ranging from an
event not felt by most people (I) to nearly total damage (XII). Between these two extreme ranges,
intensities that range from IV to XI have the potential to cause moderate to significant structural damage.
The Richter Scale is a measure of magnitude of an earthquake’s seismic energy release, with higher
numerical values for stronger earthquakes and the effects associated with each level. The relationship
between an earthquake’s magnitude (Richter) and intensity (MMI) is shown in Table 4.5-2.
According to the CGS, a probabilistic seismic hazard map is a map that shows the potential hazards of
earthquakes, which geologists and seismologists agree could occur in California. These maps are
probabilistic due to the inherent uncertainties of the size, location and the resulting ground motion effects
to a particular area of California. The seismic hazard maps are expressed in terms of the probability of
exceeding a certain ground motion (how many times the acceleration of gravity). For example, if a
location has a 10 percent probability of exceedance in 50 years map, then there is an annual probability
of 1 in 475 of being exceeded each year. Engineers use these probability measurements to design
buildings to withstand large ground motions; more than what is believed to occur during a 50-year
interval, and effectively make buildings safer (CGS, 2016a).
Ground motion probabilities are dependent upon site specific soil conditions. According to the CGS
Probabilistic Seismic Hazards Map (CGS, 2016a), there is a 10 percent probability that the peak
horizontal acceleration experienced at the site would exceed 0.205 gravity (g) from a seismic event in 50
years (CGS, 2016b; DOC, 2008). The ground-shaking probabilities have associated average peak
acceleration rates that correspond to MMI rating between VII and VIII (Table 4.5-1). Earthquakes of
these intensity values have the potential to result in damage to structures, and would be felt by all people
in the vicinity. Heavy furniture could be disturbed, and structures such as chimneys, factory stacks, and
columns could fall.
Liquefaction, Slope Instability and Surface Rupture Potential
Liquefaction is the sudden loss of soil strength caused by seismic forces acting on water-saturated,
granular soil, leading to a “quicksand” condition generating various types of ground failure. Estimating the
potential for liquefaction must account for soil types, soil density, and groundwater table depth, and the
duration and intensity of ground-shaking (USGS, 2006). Soils comprised of sand and sandy loams that
are in areas with high groundwater tables or high rainfall are subject to liquefaction. The project site is
located in an area classified as having a low liquefaction potential (USGS, 2016b).
TABLE 4.5-1 MODIFIED MERCALLI INTENSITY SCALE
Intensity Value
Intensity Description Average Peak Acceleration
I Not felt except by a very few persons under especially favorable circumstances. < 0.0015g
II Felt only by a few persons at rest, especially on upper floors of buildings. Delicately suspended objects may swing.
< 0.0015g
III Felt quite noticeably indoors, especially on upper floors of buildings, but many persons do not recognize it as an earthquake. Standing cars may rock slightly. Vibration similar to the passing of a truck. Duration estimated.
< 0.0015g
IV During the day felt indoors by many, outdoors by few. At night, some awakened. Dishes, windows, doors disturbed; walls make creaking sound. Sensation like heavy truck striking building. Standing automobiles rocked noticeably.
0.015g-0.02g
V Felt by nearly everyone, many awakened. Some dishes, windows, etc., broken; cracked plaster in a few places; unstable objects overturned. Disturbances of trees, poles, and other tall objects sometimes noticed. Pendulum clocks may stop.
0.03g-0.04g
VI Felt by all, many frightened and run outdoors. Some heavy furniture moved; a few instances of fallen plaster or damaged chimneys. Damage slight.
0.06g-0.07g
VII Everybody runs outdoors. Damage negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures; considerable in poorly built or badly designed structures; some chimneys broken. Noticed by persons driving cars.
0.10g-0.15g
VIII
Damage slight in specially designed structures; considerable in ordinary substantial buildings, with partial collapse; great in poorly built structures. Panel walls thrown out of frame structures. Fall of chimneys, factory stacks, columns, monuments, and walls. Heavy furniture overturned. Sand and mud ejected in small amounts. Changes in well water. Persons driving cars disturbed.
0.25g-0.30g
IX Damage considerable in specially designed structures; well-designed frame structures thrown out of plumb; great in substantial buildings, with partial collapse. Buildings shifted off foundations. Ground cracked conspicuously. Underground pipes broken.
0.50g-0.55g
X Some well-built wooden structures destroyed; most masonry and frame structures destroyed with foundations; ground badly cracked. Rails bent. Landslides considerable from riverbanks and steep slopes. Shifted sand and mud. Water splashed, slopped over banks.
> 0.60g
XI Few, if any, masonry structures remain standing. Bridges destroyed. Broad fissures in ground. Underground pipelines completely out of service. Earth slumps and land slips in soft ground. Rails bent greatly.
> 0.60g
XII Damage total. Waves seen on ground surface. Lines of sight and level are distorted. Objects are thrown upward into the air.
> 0.60g
Notes: g is gravity = 9.8 meters per second squared. Source: Bolt, 1988.
TABLE 4.5-2
Richter Scale Magnitude Maximum Expected Intensity (MMI) Scale
1.0 – 3.0 I
Source: USGS, 2016c.
Subsidence and Settlement
Seismic settlement is the compaction of soil materials caused by ground-shaking or the extraction of
underground fluids (water, oil, gas). Settlement can be caused by liquefaction or densification of silts and
loose sands as a result of seismic loading. Such settlement may range from a few inches to several feet,
and be controlled in part by bedrock surfaces (which prevent settlement) and old lake, slough, swamp, or
stream beds which settle readily. Static settlement can occur through increased loading of the surface or
subsurface materials, such as that imposed by foundations for structures (Das et al, 1995). Dewatering
for excavation and foundation construction can cause settlement of drying subsurface materials by
removing fine particles from the soil, by open pumping, and by consolidating compressive silts and clays,
or loose sands (Powers, 1992).
Surface Fault Rupture
Surface ground rupture along faults is generally limited to a linear zone a few meters wide. Because no
active faults have been mapped across the project site by the CGS or USGS, nor is the project site
located within an Alquist-Priolo Earthquake Special Study Zone, fault ground rupture does not represent a
hazard at the project site
Soil Resources
Soil Types
Soil types and their distribution within the project site, depicted in Figure 4.5-2, and were identified
through a review of maps provided by the Natural Resources Conservation Service (NRCS). With the
exception of urbanized areas where soils typically consist of engineered fill, the NRCS soil characteristics
describe native, undisturbed soils. Descriptions of the soil units mapped for the study area are provided
below (NRCS, 2016).
Deetz gravelly loamy sand, 0%-5% Slopes (125 / 125sc1)
This is a deep, somewhat excessively drained soil which generally occurs at elevations between 3,000
and 5,000 feet amsl. These soils comprise approximately 94 percent of the total acreage. The typical
profile of this soil is 0 to 7 inches below surface level (bsl) of gravelly loamy sand, 7 to 38 inches bsl of
stratified sand to gravelly loamy sand, and 38 to 65 inches bsl of stratified very gravelly sand to gravelly
loamy sand. This soil is characterized as having a slight hazard of erosion, a low shrink-swell potential,
and being highly corrosive to concrete. The soil unit has been assigned to hydrologic group A, which
corresponds to having a high infiltration rate when thoroughly wet. The NRCS farmland classification
identifies this soil unit as not being prime farmland. These soils have a water table at least 80 inches
below the surface.
1 Deetz gravelly loamy sand represented by 125 and 125sc are the same soil type, but due to the location are covered by different surveys done by the NRCS. Deetz 125sc is part of the Shasta-Trinity National Forest Area, Parts of Humboldt, Siskiyou, Shasta, Tehama, and Trinity Counties, California (CA707) survey, and Deetz 125 is part of the Siskiyou County, California, Central Part (CA602) survey.
!A
Figure 4.5-2 Project Site Soils
SOURCE:USDA SSURGO Soil Survey Data for Siskiyou County, updated 2013-2014; USDA aerial photograph, 7/2014; AES, 9/16/2016
Crystal Geyser Draft Environmental Impact Report / 216537
Project Site SOIL TYPES WITHIN PROJECT SITE
102 - Asta gravelly sandy loam, 15 to 50 percent slopes 125 - Deetz gravelly loamy sand, 0 to 5 percent slopes 125sc - Deetz gravelly loamy sand, 0 to 5 percent slopes
LEGEND
Asta gravelly sandy loam, 15%-50% Slopes (102)
This soil is a deep, well-drained soil associated with hydrologic group B which has a severe hazard of
erosion, a low shrink-swell potential, is moderately corrosive to concrete, and is not classified as prime
farmland. This soil comprises approximately six percent of the total acreage and generally occurs
between 3,000 and 5,000 feet amsl. Its typical profile includes 0 to 13 inches bsl of gravelly sandy loam
and 13 to 60 inches bsl of loam, silt loam, or very fine sandy loam. This soil unit has a water table at least
80 inches below the surface.
Soil Erosion
Soil erosion is the removal and transportation of soil materials from the ground surface that results in
deposition in a remote location. Common mechanisms of soil erosion include natural occurrences, such
as wind and storm water runoff, as well as human activities that may include changes to drainage
patterns and the removal of vegetation. Factors that influence the rate of soil erosion include the physical
properties of the soil, topography and slopes, rainfall and peak rainfall intensity. Erosion and potential
project-related impacts due to erosion are discussed in more detail within Section 4.8, Hydrology and
Water Quality.
Federal Earthquake Hazards Reduction Act
In 1977, the United States Congress passed the Earthquake Hazards Reduction Act to “reduce the risks
to life and property from future earthquakes in the United States through the establishment and
maintenance of an effective earthquake hazards reduction program” (NEHRP, 2016). To accomplish this,
the act established the National Earthquake Hazards Reduction Program (NEHRP). This program has
been reviewed and reauthorized periodically by Congress, with the last reauthorization occurring in 2004
(NEHRP, 2016).
NEHRP’s mission includes developing effective practices and policies for earthquake loss reduction, and
acceleration of their implementation; improving techniques for reducing earthquake vulnerabilities of
facilities and systems; improving earthquake hazards identification and risk assessment methods and
their use; and improving the understanding of earthquakes and their effects (NEHRP, 2016). The
NEHRPA assigns the Federal Emergency Management Agency (FEMA) several planning, coordinating,
and reporting responsibilities. Other NEHRP agencies include the National Institute of Standards and
Technology (NIST), National Science Foundation (NSF), and USGS.
State
Alquist-Priolo Earthquake Fault Zoning Act
The Alquist-Priolo Earthquake Fault Zoning Act was passed by the California Legislature to mitigate the
hazard of surface faulting to structures. The act’s main purpose is to prevent the construction of buildings
used for human occupancy on the surface trace of active faults. The act addresses only the hazard of
surface fault rupture and is not directed toward other earthquake hazards. Local agencies must regulate
most development in fault zones established by the State Geologist. Before a project can be permitted in
a designated Alquist-Priolo Fault Study Zone, cities and counties must require a geologic investigation to
demonstrate that proposed buildings would not be constructed across active faults (DOC, 2016).
California Seismic Hazards Mapping Act
The California Seismic Hazards Mapping Act of 1990 (Public Resources Code [PRC] Sections 2690 to
2699.6) addresses seismic hazards other than surface rupture, such as liquefaction and induced
landslides. The Seismic Hazards Mapping Act specifies that the lead agency for a project may withhold
development permits until geologic or soils investigations are conducted for specific sites and mitigation
measures are incorporated into plans to reduce hazards associated with seismicity and unstable soils
(CGS, 2008).
The State Water Resources Control Board (SWRCB) administers regulations and permitting for the
United States Environmental Protection Agency (USEPA; 55 FR 47990) for pollution generated from
stormwater under the National Pollutant Discharge Elimination System (NPDES) Permit. There are nine
Regional Water Quality Control Boards (RWQCBs) that implement the SWRCB’s jurisdiction and require
that an operator of any construction activities with ground disturbances of one acre or more obtain a
General Permit through the NPDES Stormwater Program. The project site is within the jurisdiction of the
Central Valley RWQCB (CVRWQCB). The General Permit requires that the implementations of Best
Management Practices (BMPs) be employed to reduce sedimentation into surface waters and control
erosion. The preparation of a Stormwater Pollution Prevention Plan (SWPPP) addresses control of water
pollution that includes the effects of sediments in the water during construction activities. These elements
are further explained within Section 4.8, Hydrology and Water Quality.
California Building Standards Code
The State of California provides minimum standard for building design through the California Building
Standards Code (CBC; California Code of Regulations [CCR], Title 24). Where no other building codes
apply, Chapter 18 regulates excavation, foundations, and retaining walls. The CBC also applies to
building design and construction in the state and is based on the International Building Code (IBC) used
widely throughout the country (generally adopted on a state-by-state or district-by-district basis). The
CBC has been modified for California conditions with numerous more detailed and/or more stringent
regulations.
The state earthquake protection law (California Health and Safety Code Section 19100 et seq.) requires
that structures be designed to resist stresses produced by lateral forces caused by wind and
earthquakes. Specific minimum seismic safety and structural design requirements are set forth in
Chapter 16 of the CBC. The CBC identifies seismic factors that must be considered in structural design.
Local
County of Siskiyou Land Use Element
The County of Siskiyou General Plan was adopted in 1980 and was last amended in 1997. The General
Plan serves as the overall guiding policy document for land use and development within the County by
incorporating standards of population density and building density so that circulation and public-facilities
needs can be determined. Additionally, the County General Plan promotes the protection and thoughtful
development of natural resources such as timber. The following General Plan guiding and
implementation policies associated with geologic hazards are applicable to the Proposed Project.
Policy 1 No development will be allowed in identified and potential landslide areas unless certified
by a licensed California Geologist as reasonably safe for the development proposed.
Policy 3 Proof that an area is reasonably safe from landslide, other than from a licensed California
Geologist, can be made by the County Planning Department or the Public Works
Department if an on-site field inspection indicates that the area of concern presents no
danger of landslide, i.e., obvious mapping error.
Policy 7 Specific mitigation measures will be provided that lessen soil erosion, including contour
grading, channelization, revegetation of disturbed slopes and soils, and project timing
(where feasible) to lessen the effect of seasonal factors (rainfall and wind).
Policy 8 Enforce building construction standards (Uniform Building Code2) and public works
requirements.
non-organizational in nature recreational uses, commercial/recreational uses, and public
or quasi-public uses only may be permitted, if the area is proven to be less than 30
percent slope.
The permitted uses will not create erosion or sedimentation problems.
Policy 22 No development may be allowed within the designated floodways, and any development
proven to be outside the designated floodway and within the 100-Year Flood hazard
boundary shall be in accordance with the requirements of the County’s flood plain
management ordinance.
City of Mt. Shasta General Plan Policies
Although the project site is not within the City of Mt. Shasta’s (City’s) jurisdiction, relevant local goals and
polices are listed below as they relate to adjacent and cumulative development in the City.
Policy OC-2.1 Require erosion control protection as a part of grading and development plans.
Policy OC-6.1 Allow mineral and aggregate resource lands at appropriate locations to be commercially
developed for purposes of providing construction material and industrial minerals for the
area.
2 In 2000, the Uniform Building Code was replaced by the IBC.
Policy SF-1.1 Identify areas subject to inundation.
Implementation Measure SF-1.1(a): Require that the limits of flooding resulting from a
one hundred-year storm even be shown on all permit site plans where lands may be
subject to inundation.
Policy SF-1.2 Develop a program to identify areas subject to flooding.
Implementation Measure SF-1.2(a): As studies related to flooding are prepared and
submitted for projects, the Department of Public Works shall maintain a file of such
reports and maps for public use.
Policy SF-2.1 Avoid development in areas of steep slope and high erosion potential.
Implementation Measure SF-2.1(c): Ensure that site development on steep slopes is
designed to avoid creating areas that may be subject to slippage or movement from
storm events.
Implementation Measure SF-2.1(d): Encourage the use of density transfer to avoid new
private construction in areas of steep slopes or high erosion potential.
Policy SF-7.1 Working with the County, identify routes to evacuate area residents for different types of
emergencies.
Implementation Measure SF-7.1(a): Work with the County to establish emergency
evacuation routes in the event of different categories of emergencies: severe rain or
snow storm, flood, fire, volcanic, or seismic.
4.5.4 IMPACTS
Method of Analysis
This section identifies any impacts to geology and soils that could occur from construction, operation,
and/or maintenance of the Proposed Project resulting from all modifications undertaken and proposed by
Crystal Geyser Water Company (CGWC) to operate the proposed bottling facilities. This includes all
facilities installed by CGWC as shown on Figure 3-4. The environmental setting as it existed in 2013,
when CGWC purchased the property, forms the baseline from which impacts associated with prior
construction activities are measured and evaluated, and the existing environmental setting (2016) forms
the baseline from which proposed construction activities and operation is measured. Because the
facilities previously installed by CGWC were installed within paved, graveled, or landscaped areas of the
project site, the environmental setting with respect to geology and soils has not changed between 2013
and June 2016. Impacts to and from geological resources were analyzed based on an examination of the
project site, published information regarding geological hazards of the project area, field studies, and
comparison of these factors to the significance criteria listed below. If significant impacts are likely to
occur, mitigation measures are included to increase the compatibility and safety of the Proposed Project
and to reduce impacts to less-than-significant levels. Impacts that were determined to be less than
significant in the Initial Study do not warrant further analysis and are not discussed within this
Environmental Impact Report (EIR; refer to Appendix C).
The potential for impacts associated with geology and soils resulting from off-site sewer improvements in
South Old Stage Road is addressed below. The potential for environmental impacts from the off-site
improvements described in Section 3.7 that would serve the Proposed Project, but would occur with or
without the Proposed Project, is analyzed in Section 4.12, Utilities. Environmental effects from the
planned City of Mt. Shasta State-Mandated Wastewater Treatment and Outfall Improvement Project are
discussed in Section 4.12.1, Impact 4.12-4. Environmental effects from the proposed Lassen Substation
Project are discussed in Section 4.12.3, Impact 4.12-7.
Thresholds of Significance
Criteria for determining the significance of impacts to geology and soils have been developed based on
Appendix G of the California Environmental Quality Act (CEQA) Guidelines. Impacts to geology and soils
would be considered significant if the Proposed Project would:
Expose people or structures to potential substantial adverse effects, including the risk of loss,
injury, or death involving:
o Rupture of a known earthquake fault, as delineated on the most recent Alquist-Priolo
Earthquake Fault Zoning Map issued by the State Geologist for the area or based on
other substantial evidence of a known fault;
o Strong seismic ground shaking;
o Seismic-related ground failure, including liquefaction;
o Landslides.
Result in substantial soil erosion or the loss of topsoil.
Be located in a geologic unit or soil that is unstable, or that would become unstable as a result
of the project, and potentially result in on- or off-site landslide, lateral spreading, subsidence,
liquefaction, or collapse.
Be located on expansive soil, as defined in Table 18-1-B of the Uniform Building Code (1994),
creating substantial risks to life or property.
Have soils incapable of adequately supporting the use of septic tanks or alternative wastewater
disposal systems where sewers are not available for the disposal of wastewater.
Result in the loss of availability of a known mineral resource that would be of value to the
region and the residents of the state.
Result in the loss of availability of a locally-important mineral resource recovery site delineated
on a local general plan, specific plan, or other land use plan.
Effects Found Not to be Significant
The Initial Study (Appendix C) concluded that the Proposed Project would have no impact relative to the
following two thresholds of significance:
Result in the loss of availability of a known mineral resource that would be of value to the
region and the residents of the state.
Result in the loss of availability of a locally-important mineral resource recovery site delineated
on a local general plan, specific plan, or other land use plan.
Therefore, as discussed in the Initial Study, these effects are not considered within this Environmental
Impact Report (EIR).
IMPACT 4.5-1 RESULT IN STRUCTURAL DAMAGE AND INJURY FROM SEISMIC
ACTIVITY AND RELATED GEOLOGIC HAZARDS
Significance Less than Significant
Mitigation Measures None Required
Proposed Project
The nearest mapped active fault to the project site is the Cedar Mountain fault system located
approximately 23.6 miles west of the project site. The project site is not located with an Alquist-Priolo
Earthquake Fault Zone (CGS, 2015). The closest faults are more than 130,000 years in age, and located
at least 4.6 miles from the project site. Therefore, the risk of fault rupture at the project site is considered
minor because of the infrequent nature of activity along nearby faults. Furthermore, compliance with the
CBC would require the site’s seismic-design response spectrum to be established and incorporated into
the design of all new structures. Structures and utilities would be designed to withstand seismic forces
per CBC requirements. These construction standards would minimize the seismic ground shaking effects
on developed structures.
It is anticipated that cut and fill would be balanced on site. Fill materials would be tested to ensure their
stability for use on the project site, and placement of fill would be monitored to ensure compliance with all
State and local requirements.
As mentioned previously, the project site is not located within an Alquist-Priolo Fault Zone and is
therefore not susceptible to surface rupture. Additionally, the project site does not have the potential for
liquefaction, as the soils on site are sandy with high infiltration rates. The project site is located in an area
unlikely to experience strong seismic ground shaking (CGS, 2016b; DOC, 2008). The majority of the
project site is slightly sloped (0 to 5 percent), and has a low erosion potential, which indicates a low
potential for landslides. The Asta gravelly sandy loam is more steeply sloped with a severe erosion
potential, and therefore more likely to result in landslides. However, the portion of the project site with
Asta soils is approximately 6.0 percent and in an area that is not planned for development under the
Proposed Project or under any of the wastewater disposal options (1 through 4). Therefore, the
Proposed Project would not increase the risk of landslides in the area. Potential impacts from seismic
activity are less than significant and no mitigation is required.
The project site is located adjacent to Mt. Shasta, but earthquake and ground deformation in the vicinity
of the volcano have been negligible in the last few decades (USGS, 2012). Should the volcano erupt
again, deposits of ash, lava flows, domes, and pyroclastic flows could endanger infrastructure within the
vicinity of the volcano, including the project site. Although volcanic eruptions are difficult to predict, it is
expected that if Mt. Shasta were to erupt, the eruption would be preceded by a series of earthquakes over
weeks or months, allowing for evacuation of nearby potentially impacted locations, including the project
site (USGS, 2012). Mt. Shasta’s most recent eruption was 200-300 years ago, and on average Mt.
Shasta is expected to erupt every 600-800 years (USGS, 2012). Therefore, it is not expected to erupt for
another 300 to 1,000 years. Due to the large timescale of these potential events, this is not considered a
reasonably foreseeable event. Furthermore, the City has addressed evacuation procedures in its
Emergency Plan, should any volcanic activity threaten the planning area.
Therefore, the project would have a less-than-significant impact with respect to seismic activity and
geologic hazards. No mitigation would be required.
Off-Site Sewer Improvements (Options P1 and P2)
The location of the off-site sewer improvements is approximately 1.8 miles south of the project site. This
location would be more than 4.6 miles from the nearest Quaternary fault, and more than 23.6 miles from
the nearest Alquist-Priolo fault zone. Additionally, the off-site sewer improvements are not within a
designated Alquist-Priolo fault zone. Therefore, impacts at the off-site sewer improvements location from
seismic activity and related geologic hazards would be less than significant, similar to those of the
Proposed Project. No mitigation would be required.
IMPACT 4.5-2 RESULT IN ACCELERATED RUNOFF, EROSION, AND
SEDIMENTATION
Significance After
Past construction included landscaping, water storage tanks, concrete pads, cooling towers,
transformers, juice unloading station, CO2 and nitrogen tank, vaporizers, propane tank, and equipment
installed within the existing plant building, as shown in Figure 3-4. These improvements occurred on
paved or previously disturbed areas, which required minimal grading and minimal, if any, alterations to
on-site drainage. CGWC implemented mitigation measures in accordance with the 1998 Mitigation
Agreement between Dannon and the County described in Section 3.6; thus, the following construction
best management practices were implemented during construction of the previously constructed facilities:
Develop and implement an Erosion Control Plan (ECP) in coordination with the CVRWQCB
through the Section 401 process in obtaining the stormwater management approval for the
project. At a minimum, the plan will contain the following best management practices:
o All ground-disturbing activities will be limited to the dry season (mid-May through mid-
October) to the extent possible.
o Disturbance adjacent to all drainages that ultimately drain to North Fork Cold Creek will
be limited, and vegetation left in place to the degree possible to reduce potential
sedimentation
o All stockpiled material will be placed such that potential erosion is minimized.
o Filter fabric, straw bales, and/or sediment basins will be used to reduce erosion and the
potential for in-stream sedimentation.
o Seeding and revegetation will be initiated as soon as possible (timed properly to coincide
with fall/winter precipitation) after construction completion.
Implementation of the ECP reduced the potential for accelerated runoff, erosion, and sedimentation. As a
result, impacts associated with previous constructions activities are less than significant.
Proposed Project – Future Construction Activities
Construction of the ancillary components of the Proposed Project, including the security/caretaker
residence, pH neutralization facility, and wastewater treatment infrastructure, would involve minor grading
and clearing activities within previously disturbed soils, and areas currently covered with gravel to the
south of the Plant within the central project site. Additionally, necessary pipeline installation would involve
trenching, pipeline installation, placement of backfill, and paving. Cut and fill quantities would balance on
site and the Proposed Project would not require exporting of cut material or importing of fill materials
except for potentially importing select backfill material for structure foundations. Approximately 25,600
square feet (sf), or 0.59 acres, would be graded on site. Therefore, an NPDES permit would not be
required, as the total grading of the project site would be less than one acre. The areas of soil that would
be temporarily disturbed during construction of the Proposed Project would be exposed to potential storm
events, which could generate accelerated runoff, localized erosion, and sedimentation. In addition,
construction activities could expose soil to wind erosion effects that could adversely affect both on-site
and nearby soils. This impact would be significant. The majority of soils at the project site, and all soils
that would be within the development footprint, are characterized as having only slight erosion hazards.
Upon completion of the Proposed Project, structures, gravel, or revegetated areas would eventually cover
soils exposed during construction. With the implementation of Mitigation Measure 4.5-1, which would
require construction contractors to install erosion and sediment control measures, the impact would be
reduced to less than significant.
Wastewater Treatment Option 4
In addition to the impacts described above, Wastewater Disposal Option 4 has further potential for
impacts associated with accelerated run-off and erosion, as under this option treated industrial water
would be discharged either to an on-site leach field or to an on-site irrigation system (see Section
3.5.8.3). Under Wastewater Treatment Option 4, a mainline would be installed via trenching to the two
proposed irrigation areas (see Figure 3-11), the lateral pipelines from the mainline to the sprinklers would
be installed at ground level and, therefore, would not require any ground disturbance. The irrigation
system would be used from May through October, and the leach field would be used at other times. This
seasonal use of the irrigation system would ensure that discharge via the system does not overlap with
months with high rain potential. Additionally, irrigation sprinkler use would be rotated approximately every
two hours to allow for maximum infiltration and to decrease overland flow due to oversaturation of the soil.
Furthermore, the sprinklers are sized appropriately for the vegetation existing on the project site (see
Appendix J for details). Due to the design of the irrigation system, which includes appropriately sized
sprinklers and intermittent use of sprinklers aligning with the dry season, the complete infiltration of
irrigation water would be encouraged, runoff would be minimal, and erosion due to irrigation watering
under Wastewater Treatment Option 4 would be less than significant.
Construction of the off-site sewer improvements would occur on previously disturbed and paved soils.
There would be no increase in runoff due to the off-site improvements. However, during construction,
erosion could occur as soils are displaced and result in a significant impact. Mitigation Measure S-4.5-
1 would require erosion and sediment control measures at both the project site and at the off-site
improvement area and reduce the impact to less than significant.
IMPACT 4.5-3 RESULT IN STRUCTURAL DAMAGE AND INJURY FROM
CONSTRUCTION ON EXPANSIVE SOILS
Significance Less than Significant
Proposed Project
Expansive soils have the potential to compromise the structural integrity of proposed new facilities and
roadways. Soils with high shrink-swell potentials are considered to be expansive soils. The project site
contains Deetz gravelly loamy sand, and Asta gravelly sandy loam which have low shrink-swell potentials.
Therefore, on-site soils are not considered expansive soils, and damage or injury during seismic events
due to expansive soils would not occur. Furthermore, all structures within the Proposed Project would be
designed to withstand settlement impacts resulting from unstable soil conditions and would be in
compliance with IBC requirements. Due to the low shrink-swell potential of on-site soils, the Proposed
Project would not result in structural damage or injury from construction on expansive soils. This impact
would be less than significant and no mitigation would be required.
The shrink-swell potential of the off-site sewer improvements area is low to moderate, depending on
depth (NRCS, 2016). Soils from 11 to 40 inches below ground surface (bgs) have a moderate shrink-
swell potential, while soils less than 11 inches and more than 40 inches have a low shrink-swell potential
(NRCS, 2016). The sewer pipeline that would be installed would be within the moderately expansive
cross-section of the soil. However, it is not expected that the soils would impact the improved sewer line,
as the pipeline would be encased in concrete to prevent the pipe from traffic loading. This encasement
would also protect the pipeline from expansion or compression of the soils in the 11 to 40 inch zone bgs
(see Figures 3-14 and 3-15 and refer to Appendix L). Therefore, this impact would be less than
significant and no mitigation would be required.
IMPACT 4.5-4
DISPOSAL SYSTEMS IN AREAS WHERE THE SOILS CANNOT
ADEQUATELY SUPPORT THEM
Proposed Project Options 2, 3, and 4: Less than Significant
Proposed Project
The Proposed Project would discharge all domestic wastewater into the City municipal sewer system.
Therefore, the Proposed Project would have no impact with respect to domestic water discharge to an
alternative wastewater disposal system.
As described in Section 3.5.8.3, several options for the discharge of industrial rinse and process
wastewater are being considered for the Proposed Project within this EIR, as discussed below:
Wastewater Treatment Option 1: Industrial rinse and process wastewater would be discharged
into the City’s municipal sewer system with the domestic wastewater. In this case, no alternative
wastewater disposal system would be required, and no impact would occur and no mitigation is
required.
Wastewater Treatment Option 2: Industrial rinse wastewater would be discharged into on-site
leach fields, as currently permitted by the CVRWQCB, and industrial process wastewater would
be discharged into the municipal system. As the on-site leach field is already in place and
authorized to accept industrial rinse wastewater discharge by the CVRWQCB, soils in this
location are able to support this method of wastewater disposal. This option would have a less-
than-significant impact and no mitigation is required.
Wastewater Treatment Option 3: Industrial rinse wastewater would be discharged to the
existing on-site leach field, as described under Option 2, while industrial process wastewater
would be treated on site before also being discharged into the on-site leach field. The leach field
is currently permitted to accommodate 72,000 gpd. The existing leach field would be expanded
to accept 108,000 gpd to accommodate the additional flows of the Proposed Project. As with
Option 2 above, the on-site leach field is pre-existing and authorized to accept wastewater by the
CVRWQCB. However, because the water proposed to be discharged to a leach field under
Option 3 would be from a different wastewater source and have different water quality than what
is currently permitted. The pre-existing Waste Discharge Requirement (WDR) ensured that the
soils used for the leach field were appropriate and could accept the required wastewater
discharge amount and the existing leach field operated successfully from its construction to the
closure of the Plant in 2010. A determination regarding the suitability of the soils for the proposed
expansion to the leach field will also be made during the permitting process for the proposed
change in wastewater disposal. This option would have a less-than-significant impact and no
mitigation is required.
Wastewater Treatment Option 4: Industrial rinse wastewater would be discharged to the
existing on-site leach field, as described under Option 2, while industrial process wastewater
would be treated on site and discharged into an on-site leach field, as described under Option 3,
or a proposed on-site irrigation system. As with Option 3, the existing leach field would be
expanded to accommodate the additional flows of the Proposed Project and a new or modified
WDR permit would be required. Discharging treated wastewater through the proposed irrigation
system would be supported by the soil system, as on-site Deetz soils are sandy, well-drained,
and are characterized by large depths to restrictive features and to the water table (NRCS, 2016;
Appendix H). As described under Wastewater Treatment Option 2, the WDR for the Proposed
Project will ensure that the soils used for the leach field can accept the required wastewater
discharge amount. This option would have a less-than-significant impact and no mitigation is
required.
A septic system would not be utilized in any of these options, for domestic or industrial wastewater.
Under Wastewater Treatment Options 2, 3, and 4, an alternative wastewater disposal system would be
used, and as described above, impacts would be less than significant and no mitigation is required.
Cumulative Impacts
SOILS
Significance After
Mitigation Less Than Significant
Geotechnical impacts tend to be site-specific rather than cumulative in nature. For example, seismic
events may damage or destroy a building on the project site, but the construction of a development
project on one site will not cause any adjacent parcels to become more susceptible to seismic events, nor
can a project affect local geology in such a manner as to increase risks regionally. Implementation of
future developments in combination with the Proposed Project , including growth resulting from build-out
of the City’s and County’s General Plan, would not result in increased erosion and soil hazards or expose
additional structures and people to seismic hazards. Cumulative development projects would be required
to incorporate grading/erosion plans and be developed to the latest building standards, while
incorporating recommendations from site-specific geotechnical reports prepared for these projects. The
City would ensure the implementation of mitigation measures specifically designed to avoid, reduce, or
mitigate potential impacts associated with geology and soils for all projects within City limits. Projects
outside City limits (such as the Proposed Project) would be required to similarly mitigate potential impacts
by the County. Therefore, potential cumulative impacts would be less than significant.
4.5.5 MITIGATION MEASURES
The following mitigation measures shall be implemented to reduce potential impacts associated with the
Proposed Project:
MM 4.5-1 Erosion Control Plan
Prior to earth-disturbing activities that require more than 100 cubic yards of excavation or
deposition or cover more than 10,000 sf in area, an ECP shall be prepared and submitted
to the Siskiyou County Community Development Department for review and approval for
the proposed construction activity.
The ECP shall be administered through all phases of grading and project construction.
The ECP shall incorporate BMPs to ensure that potential water quality impacts during
construction phases are minimized. The ECP shall address spill prevention and include
countermeasure plans describing measures to ensure proper collection and disposal of
all pollutants handled or produced on the site during construction, including sanitary
wastes, cement, and petroleum products. The Plan and proposed measures shall be
consistent with the County’s Land Development Manual and shall include (1)
encouraging grading in the dry season, but allowing grading during the wet season
(March to May), provided all measures listed below are implemented; (2) protecting all
finished graded slopes from erosion using such techniques as erosion control matting
and hydro-seeding; (3) protecting downstream storm drainage inlets from sedimentation;
(4) use of silt fencing and hay bales to retain sediment on the project site; (5) use of
temporary water conveyance and water diversion structures to eliminate runoff into area
waterways; (6) the requirement that it is the responsibility of the CGWC and/or Contractor
to inspect and repair all erosion control facilities within 24 hours before each forecasted
precipitation event and at the end of each work day during the rainy season; and (7) the
requirement that it is the responsibility of the CGWC and/or Contractor to inspect the
erosion and sedimentation control measures every day of a storm event, immediately
after each storm event and that all repairs shall be made immediately when the measures
are not functioning as intended. In addition, the CGWC and/or Contractor shall notify the
County of any repairs or corrections made to the erosion or sedimentation control
measures; and (8) any other suitable measures determined by the Planning Director.
The ECP shall be submitted to the Siskiyou County Planning Division for review and
approval.
The following mitigation measures shall be implemented to reduce potential impacts associated with off-
site sewer improvements:
MM S-4.5-1 Off-Site Improvements - Erosion Control Plan
Prior to earth-disturbing activities that require more than 100 cubic yards of excavation or
deposition or cover more than 10,000 sf in area, an ECP shall be prepared and submitted
to the City and County for review and approval for the proposed construction activity.
The ECP shall be administered through all phases of grading and project construction.
The ECP shall incorporate BMPs to ensure that potential water quality impacts during
construction phases are minimized. The ECP shall address spill prevention and include
countermeasure plans describing measures to ensure proper collection and disposal of
all pollutants handled or produced on the site during construction, including sanitary
wastes, cement, and petroleum products. The Plan and proposed measures shall be
consistent with the City’s and County’s Land Development Manual and shall include (1)
encouraging grading in the dry season, but allowing grading during the wet season
(March to May), provided all measures listed below are implemented; (2) protecting all
finished graded slopes from erosion using such techniques as erosion control matting
and hydro-seeding; (3) protecting downstream storm drainage inlets from sedimentation;
(4) use of silt fencing and hay bales to retain sediment on the project site; (5) use of
temporary water conveyance and water diversion structures to eliminate runoff into area
waterways; (6) the requirement that it is the responsibility of the CGWC and/or Contractor
to inspect and repair all erosion control facilities within 24 hours before each forecasted
precipitation event and at the end of each work day during the rainy season; and (7) the
requirement that it is the responsibility of the CGWC and/or Contractor to inspect the
erosion and sedimentation control measures every day of a storm event, immediately
after each storm event and that all repairs shall be made immediately when the measures
are not functioning as intended. In addition, the CGWC and/or Contractor shall notify the
City and County of any repairs or corrections made to the erosion or sedimentation
control measures; and (8) any other suitable measures determined by the County
Planning Director. The ECP shall be submitted to the City and County for review and
approval.

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4.5 GEOLOGY AND SOILS

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