Attachment D - Tech Appendix D (Geotechnical Investigation) — San Marcos City Council, December 12, 2023

Appendix D
Geotechnical Investigation

UPDATE

GEOTECHNICAL INVESTIGATION

SAN MARCOS RESTAURANT ROW

SAN MARCOS, CALIFORNIA

PREPARED FOR
LENNAR

SAN DIEGO, CALIFORNIA
DECEMBER 22, 2022
PROJECT NO. G2487-32-03
Project No. G2487-32-03
December 22, 2022
Lennar
16465 Via Esprillo, Suite 150
San Diego, California 92127
Attention: Mr. David Shepherd
Subject: UPDATE GEOTECHNICAL INVESTIGATION

SAN MARCOS RESTAURANT ROW

SAN MARCOS, CALIFORNIA
Dear Mr. Shepherd:

In accordance with your request, and our Proposal No. LG-21392, dated August 16, 2021, we have performed an update geotechnical investigation on the subject property in San Marcos, California. The accompanying report presents the recent and previous subsurface information, laboratory testing, and our conclusions and recommendations pertaining to the geotechnical aspects of project development.

The results of our study indicate that the site can be developed as planned, provided the recommendations of this report are followed.

If there are any questions regarding this report, or if we may be of further service, please contact the undersigned at your convenience.

Very truly yours,

GEOCON INCORPORATED
Troy K. Reist
CEG 2408
Trevor E. Myers
RCE 63773
David B. Evans
CEG 1860
TKR:TEM:DBE:am
(e-mail) Addressee

TABLE OF CONTENTS

1. PURPOSE AND SCOPE ................................................................................................................. 1

2. PREVIOUS GEOTECHNICAL STUDY ........................................................................................ 1

3. SITE AND PROJECT DESCRIPTION ........................................................................................... 2

4. SOIL AND GEOLOGIC CONDITIONS ........................................................................................ 2

4.1 Undocumented Fill (Qudf) .................................................................................................... 2

4.2 Younger Alluvium (Qya) ....................................................................................................... 2

4.3 Older Alluvium (Qoa)............................................................................................................ 3

5. COMPRESSION STUDY ............................................................................................................... 3

6. GROUNDWATER .......................................................................................................................... 3

7. GEOLOGIC HAZARDS ................................................................................................................. 3

7.1 Ground Rupture ..................................................................................................................... 3

7.2 Seismicity .............................................................................................................................. 4

7.3 Liquefaction ........................................................................................................................... 4

7.4 Landslides .............................................................................................................................. 4

8. CONCLUSIONS AND RECOMMENDATIONS ........................................................................... 5

8.1 General ................................................................................................................................... 5

8.2 Excavation and Soil Characteristics ...................................................................................... 5

8.3 Grading Recommendations ................................................................................................... 7

8.4 Seismic Design Criteria ......................................................................................................... 8

8.5 Foundation and Concrete Slabs-On-Grade Recommendations ........................................... 10

8.6 Concrete Flatwork ............................................................................................................... 16

8.7 Preliminary Pavement Recommendations ........................................................................... 17

8.8 Conventional Retaining Walls ............................................................................................. 20

8.9 Lateral Loading .................................................................................................................... 23

8.10 Site Drainage and Moisture Protection ................................................................................ 24

8.11 Grading and Foundation Plan Review ................................................................................. 24

LIMITATIONS AND UNIFORMITY OF CONDITIONS

MAPS AND ILLUSTRATIONS
Figure 1, Vicinity Map
Figure 2, Geologic Map

APPENDIX A

FIELD INVESTIGATION
Geocon Boring Logs B-1 through B-7
Leighton Boring Logs B-1 through B-8

APPENDIX B

LABORATORY TESTING
Table B-I, Summary of Laboratory Expansion Index Test Results Table B-II, Summary of Laboratory Water-Soluble Sulfate Test Results Consolidation Curves

APPENDIX C

STORM WATER MANAGEMENT INVESTIGATION

APPENDIX D

RECOMMENDED GRADING SPECIFICATIONS

LIST OF REFERENCES
Geocon Project No. G2487-32-03 - 1 - December 22, 2022

UPDATE GEOTECHNICAL INVESTIGATION

1. PURPOSE AND SCOPE
This report presents the results of an update geotechnical investigation for a proposed residential development located at 1020-1080 West San Marcos Boulevard in San Marcos, California (see Vicinity Map, Figure 1). The purpose of this study was to evaluate the compression characteristics of the soils underlying the proposed building areas and provide updated remedial grading and foundation design recommendations based on the current California Building Code (CBC) guidelines. In addition, this report is intended to update our previous report entitled Update Geotechnical Investigation, Old California Restaurant Row, 1000-1080 West San Marcos Boulevard, San Marcos, California, dated February 6, 2020 (Project No. G2487-42-01) and to address the current plans prepared by Project Design Consultants (PDC) provided to us on December 15, 2022.

The scope of our recent study consisted of the following:
 Reviewing readily available published and unpublished geologic literature.  Reviewing the site plans prepared by PDC, which were utilized as our base map to present our subsurface information.
 Advancing seven hollow-stem auger borings to evaluate the underlying soil and geologic conditions and to collect samples for laboratory testing (see Appendix A for boring logs).  Performing laboratory tests on selected soil samples to evaluate their physical and chemical properties for engineering analysis (see Appendix B).
 Providing storm water BMP design information (See Appendix C).  Preparing this report presenting our exploratory information and our conclusions and recommendations regarding the geotechnical aspects of developing the site as presently proposed. The approximate locations of the subsurface excavations are shown on the Geologic Map, Figure 2.

2. PREVIOUS GEOTECHNICAL STUDY
A previous geotechnical study entitled Geotechnical Investigation, Old California Restaurant Row Renovation and Additional Retail Buildings and Pavement Rehabilitation, 1000-1080 San Marcos Blvd, San Marcos, California, was prepared by Leighton Consulting Incorporated, dated January 12, 2015.

The purpose of the study was to identify and evaluate the existing soil and geologic conditions in order to provide recommendations for additional restaurant/retail buildings and pavement repairs. The study consisted of advancing eight small diameter borings and performing limited laboratory testing. We have included the borings logs in Appendix A. The approximate locations of the borings are shown on Figure 2, except Boring B-5, which was missing from their map.

Geocon Project No. G2487-32-03 - 2 - December 22, 2022

3. SITE AND PROJECT DESCRIPTION
The proposed development is located at 1020-1080 West San Marcos Boulevard in San Marcos, California. The approximate 11-acre site was originally developed in 1978 with several dining establishments known as Old California Restaurant Row, which included over a dozen restaurant locations and associated asphalt concrete parking areas. It is our understanding that the proposed project consists of redeveloping the property for a 3-story, 202-unit condominium complex with associated infrastructure improvements including a 1.1-acre neighborhood park and 10,400 square feet of dining and retail space. No subterranean parking or basements are planned.

The geometric grading volume provided by PDC consists of approximately 41,140 cubic yards of cut and 225,560 cubic yards of fill, which would require approximately 184,420 cubic yards of import to achieve the desired finish grades. However, these quantities do not consider remedial grading or shrinking of the materials. Maximum cut and fill depths prior to remedial grading will be on the order of 3 and 8 feet, respectively.

The descriptions contained herein are based upon the site reconnaissance and our understanding of the project. If project details vary significantly from those outlined herein, Geocon Incorporated should be notified for review and possible revisions to this report prior to final design submittal.

4. SOIL AND GEOLOGIC CONDITIONS
The geologic units encountered on the property include undocumented fill and younger and older alluvium. Each of the units is described below in order of increasing age. Their mapped extent is shown on the Geologic Map.

4.1 Undocumented Fill (Qudf)
Undocumented fill was encountered in each of the exploratory borings and varied in thickness between 3 and 5 feet. The fill consists of damp to very moist, silty to clayey sands and clays. These fills are unsuitable for additional fill loads and will require remedial grading.

4.2 Younger Alluvium (Qya)
Younger alluvial deposits, up to 6½-feet-thick, were encountered in Boring B-4 and the previous borings advanced by Leighton (Borings B-6 through B-8) within the north central portion of the site. The younger alluvium consists of stiff, very moist to wet, dark gray, sandy clay and clayey sands. The younger alluvium is potentially compressible and will require remedial grading within areas of planned development.

Geocon Project No. G2487-32-03 - 3 - December 22, 2022

4.3 Older Alluvium (Qoa)
Older alluvial deposits were encountered in each of the exploratory borings advanced across the site.

These deposits consist of medium dense to very dense, silty to clayey, fine to coarse sands and hard, sandy to silty clays and silts with some gravels present below 17 feet. A compression study was performed on the material to evaluate the potential for leaving this unit in place as discussed in Section

5.0 below.

5. COMPRESSION STUDY
Older alluvial deposits were encountered at depths of approximately 3 to 9 feet below the existing ground surface. To evaluate the possibility of leaving this unit in-place, consolidation testing was performed on several relatively undisturbed samples of this material. Based on the laboratory test results presented in Appendix B, the older alluvium possesses adequate engineering properties to remain in- place and receive the proposed fills and/or structural loads.

6. GROUNDWATER
Groundwater was encountered in all the exploratory borings performed across the site, which varied between 8 and 24 feet below the existing ground surface. The groundwater elevations are expected to fluctuate seasonally and may affect remedial grading. In this regard, remedial grading may encounter wet soils and excavation and compaction difficulty, particularly if grading is planned during the winter months.

A non-operational/abandoned well was observed in the northwestern portion of the property (see Figure 2). The well should be properly abandoned/removed in accordance with San Diego County regulatory requirements.

7. GEOLOGIC HAZARDS

7.1 Ground Rupture
USGS (2016) shows that there are no mapped Quaternary faults crossing or trending toward the property. In addition, the site is not located within a currently established Alquist-Priolo Earthquake Fault Zone.

The nearest known active faults are the Rose Canyon Fault zone and the Newport-Inglewood Fault, located approximately 10 miles west of the site. Based on this study, it is our opinion that the risk associated with ground rupture hazard is considered low.

Geocon Project No. G2487-32-03 - 4 - December 22, 2022

7.2 Seismicity
San Diego County and Southern California region is seismically active. Considerations important in seismic design include the frequency and duration of motion and the soil conditions underlying the site.

Seismic design of structures should be performed in accordance with the CBC guidelines currently adopted by the local agency. The risk associated with strong ground shaking due to earthquakes at the site is no greater than that for the region.

7.3 Liquefaction
Liquefaction typically occurs when a site is located in a zone with seismic activity, onsite soils are cohesionless, groundwater is encountered within 50 feet of the surface, and soil densities are less than about 70 percent of the maximum dry densities. If all four criteria are met, a seismic event could result in a rapid increase in pore water pressure from the earthquake-generated ground accelerations. The potential for liquefaction at the site is considered to be low due to the relative density of the older alluvium.

7.4 Landslides
No evidence of ancient landslide deposits was encountered at the site during the geotechnical investigation.

Geocon Project No. G2487-32-03 - 5 - December 22, 2022

8. CONCLUSIONS AND RECOMMENDATIONS

8.1 General

8.1.1 No soil or geologic conditions were encountered that, in the opinion of Geocon Incorporated, would preclude the development of the property as proposed, provided the recommendations of this report are followed.

8.1.2 The site is underlain by undocumented fill, younger and older alluvium. The undocumented fill and younger alluvial deposits are unsuitable in their present condition and will require remedial grading in the form of removal and compaction where improvements are planned.

The actual extent of unsuitable soil removal will be determined in the field by the geotechnical engineer and/or engineering geologist.

8.1.3 The proposed structures can be supported by conventional continuous and isolated spread foundations supported entirely in compacted fill or competent older alluvium.

8.1.4 The existing structures, foundation systems, pavement, utility lines, etc., should be removed and exported from the site prior to grading. Undocumented fills associated with these items and with past underground improvements should also be removed and properly compacted. Geocon Incorporated should observe the underlying geologic conditions and provide testing and observation services during the backfill of the resulting excavations where necessary.

8.1.5 The existing well identified during our field reconnaissance should be destroyed in accordance with the County of San Diego Department of Environmental Health. Once the project has been approved, a licensed drilling contractor with a valid C57 license will need to be contracted to properly destroy the well.

8.2 Excavation and Soil Characteristics

8.2.1 Excavation of the surficial deposits (undocumented fill and younger alluvium) should be possible with light to moderate effort using conventional heavy-duty equipment. These deposits may be very moist to saturated during the winter or early spring depending on preceding precipitation. Overly wet soils will require drying or mixing with drier material prior to their use as compacted fill.

8.2.2 The soils encountered in the field investigation are considered to be “expansive” (expansion index [EI] of 90 or less) as defined by 2019 California Building Code (CBC) Section 1803.5.3. Table 8.2.1 presents soil classifications based on the expansion index. We Geocon Project No. G2487-32-03 - 6 - December 22, 2022
expect a majority of the soil encountered possesses a “low” to “medium” expansion potential (expansion index of 90 or less).

TABLE 8.2.1

EXPANSION CLASSIFICATION BASED ON EXPANSION INDEX
Expansion Index (EI) ASTM 4829
Expansion Classification
2019 CBC
Expansion Classification
0 – 20 Very Low Non-Expansive
21 – 50 Low
Expansive
51 – 90 Medium
91 – 130 High
Greater Than 130 Very High

8.2.3 The laboratory test results indicate that the near-surface on-site materials at the locations tested possess Not Applicable sulfate severity to concrete structures as defined by 2019 CBC Section 1904 and ACI 318-14 Chapter 19. Table 8.2.2 presents a summary of concrete requirements set forth by 2019 CBC Section 1904 and ACI 318. ACI guidelines should be followed when determining the type of concrete to be used. The presence of water-soluble sulfates is not a visually discernible characteristic; therefore, other soil samples from the site could yield different concentrations. Additionally, over time landscaping activities (i.e., addition of fertilizers and other soil nutrients) may affect the concentration.

TABLE 8.2.2

REQUIREMENTS FOR CONCRETE EXPOSED TO SULFATE-CONTAINING SOLUTIONS Exposure Class
Water-Soluble
Sulfate (SO4)
Percent
by Weight
Cement
Type (ASTM C
150)
Maximum
Water to
Cement Ratio
by Weight1
Minimum
Compressive
Strength (psi)
S0 SO4<0.10 No Type Restriction n/a 2,500
S1 0.10<SO4<0.20 II 0.50 4,000
S2 0.20<SO4<2.00 V 0.45 4,500
S3
Option 1
SO4>2.00
V+Pozzolan or Slag 0.45 4,500
Option 2 V 0.40 5,000
1 Maximum water to cement ratio limits do not apply to lightweight concrete

8.2.4 Geocon Incorporated does not practice in the field of corrosion engineering. Therefore, if improvements that could be susceptible to corrosion are planned, we recommend that further evaluation by a corrosion engineer be performed.

Geocon Project No. G2487-32-03 - 7 - December 22, 2022

8.3 Grading Recommendations

8.3.1 All grading should be performed in accordance with the attached Recommended Grading Specifications (Appendix D). Where the recommendations of this section conflict with Appendix D, the recommendations of this section take precedence. All earthwork should be observed and all fills tested for proper compaction by Geocon Incorporated.

8.3.2 Prior to commencing grading, a preconstruction conference should be held at the site with the owner or developer, grading contractor, civil engineer, and geotechnical engineer in attendance. Special soil handling and/or the grading plans can be discussed at that time.

8.3.3 Site preparation should begin with the removal of all deleterious material and vegetation. The depth of removal should be such that material exposed in cut areas or soils to be used as fill are relatively free of organic matter and construction debris. Material generated during stripping and/or site demolition should be exported from the site.

8.3.4 All existing underground improvements and building foundations within proposed structural areas should be removed and the resulting depressions properly backfilled in accordance with the procedures described herein.

8.3.5 The undocumented fill and younger alluvium across the site should be removed to expose unyielding older alluvium, moisture conditioned, and properly compacted to provide uniform foundation conditions. The actual extent of unsuitable soil removal will be determined in the field by the geotechnical engineer and/or engineering geologist.

8.3.6 After removal of unsuitable materials is performed, the site should then be brought to final subgrade elevations with structural fill compacted in layers. In general, soils native to the site are suitable for re-use as fill if free from vegetation, debris, and other deleterious material.

Layers of fill should be no thicker than will allow for adequate bonding and compaction. All fill, including backfill and scarified ground surfaces, should be compacted to at least 90 percent of maximum dry density at or above optimum moisture content, as determined in accordance with ASTM Test Procedure D1557. Fill materials below optimum moisture content will require additional moisture conditioning prior to placing additional fill.

8.3.7 Where practical, the upper 3 feet of the building pads should be comprised of soil with a “very low” to “low” expansion potential (i.e., Expansion Index of 50 or less). The more highly expansive fill soils should be placed in the deeper fill areas, if present.

Geocon Project No. G2487-32-03 - 8 - December 22, 2022

8.3.8 Prior to placing fill, the ground surface should be scarified to a depth of 12 inches, moisture conditioned, and compacted to a dry density of at least 90 percent of the laboratory maximum dry density near to slightly above optimum moisture content, as determined by ASTM Test Method D 1557. Deeper processing and/or removal may be necessary in areas where loose, wet or dry soils are encountered.

8.3.9 It is the responsibility of the contractor to ensure that all excavations and trenches are properly shored and maintained in accordance with applicable OSHA rules and regulations in order to maintain safety and maintain the stability of adjacent existing improvements.

8.3.10 Import fill should consist of granular materials with a “very low” to “low” expansion potential (EI of 50 or less) free of deleterious material or stones larger than 3 inches, and should be compacted as recommended above. Geocon Incorporated should be notified of the import soil source and should perform laboratory testing of import soil prior to its arrival at the site to determine its suitability as fill material.

8.4 Seismic Design Criteria

8.4.1 Table 8.4.1 summarizes site-specific design criteria obtained from the 2019 California Building Code (CBC; Based on the 2018 International Building Code [IBC] and ASCE 7-16), Chapter 16 Structural Design, Section 1613 Earthquake Loads. We used the computer program U.S. Seismic Design Maps, provided by the Structural Engineers Association (SEA) to calculate the seismic design parameters. The short spectral response uses a period of 0.2 second. We evaluated the Site Class based on the discussion in Section 1613.2.2 of the 2019 CBC and Table 20.3-1 of ASCE 7-16. The values presented herein are for the risk-targeted maximum considered earthquake (MCE R). Sites designated as Site Class D, E and F may require additional analyses if requested by the project structural engineer and client.

Geocon Project No. G2487-32-03 - 9 - December 22, 2022
TABLE 8.4.1
2019 CBC SEISMIC DESIGN PARAMETERS
Parameter Value 2019 CBC Reference
Site Class D Section 1613.2.2
MCER Ground Motion Spectral Response
Acceleration – Class B (short), SS

0.896g Figure 1613.2.1(1)
MCER Ground Motion Spectral Response
Acceleration – Class B (1 sec), S1

0.33g Figure 1613.2.1(2)
Site Coefficient, FA 1.141 Table 1613.2.3(1)
Site Coefficient, FV 1.97* Table 1613.2.3(2)
Site Class Modified MCER Spectral Response
Acceleration (short), SMS

1.023g Section 1613.2.3 (Eqn 16-36)
Site Class Modified MCER Spectral Response
Acceleration – (1 sec), SM1

0.651g* Section 1613.2.3 (Eqn 16-37)
5% Damped Design
Spectral Response Acceleration (short), SDS

0.682g Section 1613.2.4 (Eqn 16-38)
5% Damped Design
Spectral Response Acceleration (1 sec), SD1

0.434g* Section 1613.2.4 (Eqn 16-39)
* Using the code-based values presented in this table, in lieu of a performing a ground motion hazard analysis, requires the exceptions outlined in ASCE 7-16 Section 11.4.8 be followed by the project structural engineer. Per Section 11.4.8 of ASCE/SEI 7-16, a ground motion hazard analysis should be performed for projects for Site Class “E” sites with Ss greater than or equal to 1.0g and for Site Class “D” and “E” sites with S1 greater than 0.2g. Section 11.4.8 also provides exceptions which indicates that the ground motion hazard analysis may be waived provided the exceptions are followed.

8.4.2 Table 8.4.2 presents the mapped maximum considered geometric mean (MCE G) seismic design parameters for projects located in Seismic Design Categories of D through F in accordance with ASCE 7-16.

TABLE 8.4.2
ASCE 7-16 PEAK GROUND ACCELERATION
Parameter Value ASCE 7-16 Reference
Mapped MCEG Peak Ground Acceleration, PGA 0.387g Figure 22-7 Site Coefficient, FPGA 1.213 Table 11.8-1
Site Class Modified MCEG
Peak Ground Acceleration, PGAM

0.47g Section 11.8.3 (Eqn 11.8-1)

8.4.3 Conformance to the criteria in Tables 8.4.1 and 8.4.2 for seismic design does not constitute any kind of guarantee or assurance that significant structural damage or ground failure will not occur in the event of a large earthquake. The primary goal of seismic design is to protect life, not to avoid all damage, since such design may be economically prohibitive.

Geocon Project No. G2487-32-03 - 10 - December 22, 2022

8.4.4 The project structural engineer and architect should evaluate the appropriate Risk Category and Seismic Design Category for the planned structures. The values presented herein assume a Risk Category of II and resulting in a Seismic Design Category D. Table 8.4.3 presents a summary of the risk categories in accordance with ASCE 7-16.

TABLE 8.4.3
ASCE 7-16 RISK CATEGORIES
Risk
Category Building Use Examples
I Low risk to Human Life at Failure Barn, Storage Shelter II Nominal Risk to Human Life at Failure
(Buildings Not Designated as I, III or IV)
Residential, Commercial
and Industrial Buildings
III Substantial Risk to Human Life at Failure
Theaters, Lecture Halls, Dining Halls,
Schools, Prisons, Small Healthcare
Facilities, Infrastructure Plants, Storage
for Explosives/Toxins
IV Essential Facilities
Hazardous Material Facilities,
Hospitals, Fire and Rescue, Emergency
Shelters, Police Stations, Power
Stations, Aviation Control Facilities,
National Defense, Water Storage

8.5 Foundation and Concrete Slabs-On-Grade Recommendations

8.5.1 The foundation recommendations herein are for proposed one- to three-story residential structures. The foundation recommendations have been separated into three categories based on either the maximum and differential fill thickness or Expansion Index. The foundation category criteria are presented in Table 8.5.1.

TABLE 8.5.1

FOUNDATION CATEGORY CRITERIA
Foundation
Category
Maximum Fill
Thickness, T (Feet)
Differential Fill
Thickness, D (Feet) Expansion Index (EI)
I T<20 -- EI<50
II 20<T<50 10<D<20 50<EI<90
III T>50 D>20 90<EI<130

8.5.2 We will provide final foundation categories for each building or lot after finish pad grades have been achieved, the underlying fill-bedrock geometry is evaluated and we perform laboratory testing of the subgrade soil.

Geocon Project No. G2487-32-03 - 11 - December 22, 2022

8.5.3 Table 8.5.2 presents minimum foundation and interior concrete slab design criteria for conventional foundation systems.

TABLE 8.5.2

CONVENTIONAL FOUNDATION RECOMMENDATIONS BY CATEGORY
Foundation
Category
Minimum Footing
Embedment
Depth, D (inches)
Minimum Continuous
Footing
Reinforcement
Minimum Footing
Width (Inches)
I 12 Two No. 4 bars, one top
and one bottom
12 – Continuous, WC
24 – Isolated, WI
II 18 Four No. 4 bars, two top
and two bottom
III 24 Four No. 5 bars, two top
and two bottom

8.5.4 The foundations should be embedded in accordance with the recommendations herein and the Wall/Column Footing Dimension Detail. The embedment depths should be measured from the lowest adjacent pad grade for both interior and exterior footings. Footings should be deepened such that the bottom outside edge of the footing is at least 7 feet horizontally from the face of the slope (unless designed with a post-tensioned foundation system as discussed herein).

Wall/Column Footing Dimension Detail

8.5.5 The proposed structures can be supported on a shallow foundation system founded in the compacted fill/formational materials. Table 8.5.3 provides a summary of the foundation design recommendations.

Geocon Project No. G2487-32-03 - 12 - December 22, 2022 TABLE 8.5.3

SUMMARY OF FOUNDATION RECOMMENDATIONS
Parameter Value
Allowable Bearing Capacity 2,000 psf
Bearing Capacity Increase
500 psf per Foot of Depth
300 psf per Foot of Width
Maximum Allowable Bearing Capacity 4,000 psf
Estimated Total Static Settlement* 1 Inch
Estimated Differential Static Settlement* ½ Inch in 40 Feet

8.5.6 The bearing capacity values presented herein are for dead plus live loads and may be increased by one-third when considering transient loads due to wind or seismic forces.

8.5.7 The concrete slab-on-grades should be a designed in accordance with Table 8.5.4.

TABLE 8.5.4

CONVENTIONAL SLAB-ON-GRADE RECOMMENDATIONS BY CATEGORY
Foundation
Category
Minimum
Concrete Slab
Thickness
(inches)
Interior Slab
Reinforcement
Typical Slab
Underlayment
I 4 6 x 6 - 10/10 welded wire mesh at
slab mid-point
3 to 4 Inches of
Sand/Gravel/Base II 4 No. 3 bars at 24 inches on center, both directions
III 5 No. 3 bars at 18 inches on center,
both directions

8.5.8 Slabs that may receive moisture-sensitive floor coverings or may be used to store moisture- sensitive materials should be underlain by a vapor retarder. The vapor retarder design should be consistent with the guidelines presented in the American Concrete Institute’s (ACI) Guide for Concrete Slabs that Receive Moisture-Sensitive Flooring Materials (ACI 302.2R-06). The vapor retarder used should be specified by the project architect or developer based on the type of floor covering that will be installed and if the structure will possess a humidity controlled environment.

8.5.9 The bedding sand thickness should be determined by the project foundation engineer, architect, and/or developer. However, we should be contacted to provide recommendations if the bedding sand is thicker than 6 inches. It is common to see 3 inches and 4 inches of sand Geocon Project No. G2487-32-03 - 13 - December 22, 2022 below the concrete slab-on-grade for 5-inch and 4-inch thick slabs, respectively, in the southern California area. The foundation design engineer should provide appropriate concrete mix design criteria and curing measures to assure proper curing of the slab by reducing the potential for rapid moisture loss and subsequent cracking and/or slab curl. We suggest that the foundation design engineer present the concrete mix design and proper curing methods on the foundation plans. It is critical that the foundation contractor understands and follows the recommendations presented on the foundation plans.

8.5.10 As an alternative to the conventional foundation recommendations, consideration should be given to the use of post-tensioned concrete slab and foundation systems for the support of the proposed structures. The post-tensioned systems (foundation dimensions and embedment depths, slab thickness and steel placement) should be designed by a structural engineer experienced in post-tensioned slab design and design criteria of the Post-Tensioning Institute (PTI) DC 10.5-12 Standard Requirements for Design and Analysis of Shallow Post-Tensioned Concrete Foundations on Expansive Soils or WRI/CRSI Design of Slab-on-Ground Foundations, as required by the 2019 California Building Code (CBC Section 1808.6.2).

Although this procedure was developed for expansive soil conditions, it can also be used to reduce the potential for foundation distress due to differential fill settlement. The post- tensioned design should incorporate the geotechnical parameters presented in Table 8.5.5 for the particular Foundation Category designated. The parameters presented in Table 8.5.5 are based on the guidelines presented in the PTI DC 10.5 design manual.

TABLE 8.5.5

POST-TENSIONED FOUNDATION SYSTEM DESIGN PARAMETERS
Post-Tensioning Institute (PTI) DC10.5
Design Parameters
Foundation Category

I II III
Thornthwaite Index -20 -20 -20
Equilibrium Suction 3.9 3.9 3.9
Edge Lift Moisture Variation Distance, eM (Feet) 5.3 5.1 4.9 Edge Lift, yM (Inches) 0.61 1.10 1.58
Center Lift Moisture Variation Distance, eM
(Feet) 9.0 9.0 9.0
Center Lift, yM (Inches) 0.30 0.47 0.66

8.5.11 The foundations for the post-tensioned slabs should be embedded in accordance with the recommendations of the structural engineer. If a post-tensioned mat foundation system is planned, the slab should possess a thickened edge with a minimum width of 12 inches and extend below the clean sand or crushed rock layer.

Geocon Project No. G2487-32-03 - 14 - December 22, 2022

8.5.12 If the structural engineer proposes a post-tensioned foundation design method other than PTI, DC 10.5:
 The deflection criteria presented in Table 8.5.5 are still applicable.  Interior stiffener beams should be used for Foundation Categories II and III.  The width of the perimeter foundations should be at least 12 inches.  The perimeter footing embedment depths should be at least 12 inches, 18 inches and 24 inches for foundation categories I, II, and III, respectively. The embedment depths should be measured from the lowest adjacent pad grade.

8.5.13 Foundation systems for the lots that possess a foundation Category I and a “very low” expansion potential (expansion index of 20 or less) can be designed using the method described in Section 1808 of the 2019 CBC. If post-tensioned foundations are planned, an alternative, commonly accepted design method (other than PTI, DC 10.5) can be used.

However, the post-tensioned foundation system should be designed with a total and differential deflection of 1 inch. Geocon Incorporated should be contacted to review the plans and provide additional information, if necessary.

8.5.14 If an alternate design method is contemplated, Geocon Incorporated should be contacted to evaluate if additional expansion index testing should be performed to identify the lots that possess a “very low” expansion potential (expansion index of 20 or less).

8.5.15 Our experience indicates post-tensioned slabs may be susceptible to excessive edge lift from tensioning, regardless of the underlying soil conditions. Placing reinforcing steel at the bottom of the perimeter footings and the interior stiffener beams may mitigate this potential. The structural engineer should design the foundation system to reduce the potential of edge lift occurring for the proposed structures.

8.5.16 During the construction of the post-tension foundation system, the concrete should be placed monolithically. Under no circumstances should cold joints form between the footings/grade beams and the slab during the construction of the post-tension foundation system unless designed by the structural engineer.

8.5.17 Isolated footings outside of the slab area, if present, should have the minimum embedment depth and width recommended for conventional foundations for a particular Foundation Category. The use of isolated footings, which are located beyond the perimeter of the building and support structural elements connected to the building, are not recommended for Category III. Where this condition cannot be avoided, the isolated footings should be connected to the building foundation system with grade beams in both directions. In addition, consideration Geocon Project No. G2487-32-03 - 15 - December 22, 2022 should be given to connecting patio slabs, which exceed 5 feet in width, to the building foundation to reduce the potential for future separation to occur.

8.5.18 Interior stiffening beams should be incorporated into the design of the foundation system in accordance with the PTI design procedures.

8.5.19 Special subgrade presaturation is not deemed necessary prior to placing concrete; however, the exposed foundation and slab subgrade soil should be moisture conditioned, as necessary, to maintain a moist condition as would be expected in any such concrete placement.

8.5.20 Where buildings or other improvements are planned near the top of a slope 3:1 (horizontal:vertical) or steeper, special foundation and/or design considerations are recommended due to the tendency for lateral soil movement to occur.  For fill slopes less than 20 feet high or cut slopes regardless of height, footings should be deepened such that the bottom outside edge of the footing is at least 7 feet horizontally from the face of the slope.
 When located next to a descending 3:1 (horizontal:vertical) fill slope or steeper, the foundations should be extended to a depth where the minimum horizontal distance is equal to H/3 (where H equals the vertical distance from the top of the fill slope to the base of the fill soil) with a minimum of 7 feet but need not exceed 40 feet. The horizontal distance is measured from the outer, deepest edge of the footing to the face of the slope. A post-tensioned slab and foundation system or mat foundation system can be used to reduce the potential for distress in the structures associated with strain softening and lateral fill extension. Specific design parameters or recommendations for either of these alternatives can be provided once the building location and fill slope geometry have been determined.
 If swimming pools are planned, Geocon Incorporated should be contacted for a review of specific site conditions.
 Swimming pools located within 7 feet of the top of cut or fill slopes are not recommended. Where such a condition cannot be avoided, the portion of the swimming pool wall within 7 feet of the slope face be designed assuming that the adjacent soil provides no lateral support. This recommendation applies to fill slopes up to 30 feet in height, and cut slopes regardless of height. For swimming pools located near the top of fill slopes greater than 30 feet in height, additional recommendations may be required and Geocon Incorporated should be contacted for a review of specific site conditions.
 Although other improvements, which are relatively rigid or brittle, such as concrete flatwork or masonry walls, may experience some distress if located near the top of a slope, it is generally not economical to mitigate this potential. It may be possible, however, to incorporate design measures which would permit some lateral soil movement without causing extensive distress. Geocon Incorporated should be consulted for specific recommendations.

8.5.21 The recommendations of this report are intended to reduce the potential for cracking of slabs and foundations due to expansive soil (if present), differential settlement of fill soil with Geocon Project No. G2487-32-03 - 16 - December 22, 2022 varying thicknesses. However, even with the incorporation of the recommendations presented herein, foundations, stucco walls, and slabs-on-grade placed on such conditions may still exhibit some cracking due to soil movement and/or shrinkage. The occurrence of concrete shrinkage cracks is independent of the supporting soil characteristics. Their occurrence may be reduced by limiting the slump of the concrete, proper concrete placement and curing, and by the placement of crack control joints at periodic intervals, in particular, where re-entrant slab corners occur.

8.5.22 Concrete slabs should be provided with adequate crack-control joints, construction joints and/or expansion joints to reduce unsightly shrinkage cracking. The design of joints should consider criteria of the American Concrete Institute when establishing crack-control spacing.

Additional steel reinforcing, concrete admixtures and/or closer crack control joint spacing should be considered where concrete-exposed finished floors are planned.

8.5.23 Geocon Incorporated should be consulted to provide additional design parameters as required by the structural engineer.

8.5.24 We should observe the foundation excavations prior to the placement of reinforcing steel to check that the exposed soil conditions are similar to those expected and that they have been extended to the appropriate bearing strata. If unexpected soil conditions are encountered, foundation modifications may be required.

8.6 Concrete Flatwork

8.6.1 The following recommendations apply to exterior concrete flatwork where near surface soils are low to medium expansive (EI less than 90). Exterior slabs not subjected to vehicular traffic should be a minimum of 4 inches thick and reinforced with 6 x 6-6/6 welded wire mesh or No. 3 rebar spaced at 24 inches on center in both directions. The mesh should be placed in the middle of the slab. Proper mesh positioning is critical to future performance of the slabs. The contractor should take extra measures to provide proper mesh placement. Prior to construction of slabs, the upper 12 inches of subgrade soils should be moisture conditioned at or slightly above optimum moisture content and compacted to at least 90 percent of the laboratory maximum dry density per ASTM 1557.

8.6.2 Where highly expansive soils (EI greater than 90) are present near finish grade, the following recommendations apply. Exterior slabs should be at least 5 inches thick and reinforced with No. 3 steel bars spaced 18 inches on center each direction positioned at the slab midpoint.

Driveways should be constructed with a 6-inch deep slab edge (measured from the bottom of the slab). Slabs should be doweled to the building foundation where they abut the stem wall.

Geocon Project No. G2487-32-03 - 17 - December 22, 2022 Sidewalks should be doweled to the curbs. Prior to construction of slabs, the upper 12 inches of subgrade soils should scarified and moisture conditioned to a minimum of 3% above optimum moisture content just prior to placing the concrete. Moisture conditioning should be observed and checked by a representative of Geocon Incorporated.

8.6.3 Consideration should be given to adding concrete cut-off walls beneath exterior flatwork supported by highly expansive soils (EI greater than 90). The cut-off walls are recommended where any water (e.g. landscape) may migrate laterally beneath the flatwork and cause adverse soil movement. The cut-off walls should be located along the perimeter of the concrete slab adjacent to landscaping areas and extend at least 6-inches into the soil subgrade.

8.6.4 Concrete flatwork should be provided with crack control joints to reduce and/or control shrinkage cracking. Crack control spacing should be determined by the project structural engineer based upon the slab thickness and intended usage. Criteria of the American Concrete Institute (ACI) should be taken into consideration when establishing crack control spacing. A 4-inch-thick slab should have a maximum joint spacing of 10 feet. Subgrade soil for exterior slabs not subjected to vehicle loads should be compacted in accordance with criteria presented above prior to concrete placement. Subgrade soil should be properly compacted and the moisture content of subgrade soil should be checked prior to placing concrete.

8.6.5 The recommendations of this report are intended to reduce the potential for cracking of slabs due to expansive soil (if present), differential settlement of existing soil or soil with varying thicknesses. However, even with the incorporation of the recommendations presented herein, foundations, stucco walls, and slabs-on-grade placed on such conditions may still exhibit some cracking due to soil movement and/or shrinkage. Periotic maintenance such as slab replacement and/or grinding of elevated slab margins may be necessary due to the highly expansive soils. The occurrence of concrete shrinkage cracks is independent of the supporting soil characteristics. Their occurrence may be reduced and/or controlled by limiting the slump of the concrete, proper concrete placement and curing, and by the placement of crack control joints at periodic intervals, in particular, where re-entrant slab corners occur.

8.7 Preliminary Pavement Recommendations

8.7.1 We calculated the preliminary flexible pavement sections in general conformance with the Caltrans Method of Flexible Pavement Design (Highway Design Manual, Section 608.4) using an estimated Traffic Index (TI) of 4.5, 5.0, 6.0, and 7.0 for parking stalls, driveways, medium truck traffic areas, and heavy truck traffic areas, respectively. The project civil engineer and owner should review the pavement designations to determine appropriate locations for pavement thickness. The final pavement sections for the driveways and parking areas should be based on the R-Value of the subgrade soil encountered at final subgrade Geocon Project No. G2487-32-03 - 18 - December 22, 2022 elevation. We have assumed an R-Value of 5 and 78 for the subgrade soil and base materials, respectively, for the purposes of this preliminary analysis. Table 8.7.1 presents the preliminary flexible pavement sections.

TABLE 8.7.1

PRELIMINARY FLEXIBLE PAVEMENT SECTION
Location
Assumed
Traffic
Index
Assumed
Subgrade
R-Value
Asphalt
Concrete
(inches)
Class 2
Aggregate
Base (inches)
Parking stalls for automobiles
and light-duty vehicles 4.5 20 3 8
Driveways for automobiles
and light-duty vehicles 5.0 20 3 10
Medium truck traffic areas 6.0 20 3.5 15
Driveways for heavy truck traffic 7.0 20 4 16

8.7.2 Prior to placing base materials, the upper 12 inches of the subgrade soil should be scarified, moisture conditioned as necessary, and compacted to a dry density of at least 95 percent of the laboratory maximum dry density near to slightly above optimum moisture content as determined by ASTM D 1557. Similarly, the base material should be compacted to a dry density of at least 95 percent of the laboratory maximum dry density near to slightly above optimum moisture content. Asphalt concrete should be compacted to a density of at least 95 percent of the laboratory Hveem density in accordance with ASTM D 2726.

8.7.3 Base materials should conform to Section 26-1.02A of the Standard Specifications for The State of California Department of Transportation (Caltrans) with a ¾-inch maximum size aggregate. The asphalt concrete should conform to Section 203-6 of the Standard Specifications for Public Works Construction (Greenbook).

8.7.4 A rigid Portland cement concrete (PCC) pavement section should be placed in driveway entrance aprons and trash bin loading/storage areas. The concrete pad for trash truck areas should be large enough such that the truck wheels will be positioned on the concrete during loading. We calculated the rigid pavement section in general conformance with the procedure recommended by the American Concrete Institute report ACI 330R-08 Guide for Design and Construction of Concrete Parking Lots using the parameters presented in Table 8.7.2.

Geocon Project No. G2487-32-03 - 19 - December 22, 2022 TABLE 8.7.2

RIGID PAVEMENT DESIGN PARAMETERS
Design Parameter Design Value
Modulus of subgrade reaction, k 50 pci
Modulus of rupture for concrete, MR 500 psi
Traffic Category, TC A and C
Average daily truck traffic, ADTT 10 and 100

8.7.5 Based on the criteria presented herein, the PCC pavement sections should have a minimum thickness as presented in Table 8.7.3.

TABLE 8.7.3

RIGID PAVEMENT RECOMMENDATIONS
Location Portland Cement Concrete (inches)
Automobile Parking Areas (TC=A) 6.0
Heavy Truck and Fire Lane Areas (TC=C) 7.5

8.7.6 The PCC pavement should be placed over subgrade soil that is compacted to a dry density of at least 95 percent of the laboratory maximum dry density near to slightly above optimum moisture content. This pavement section is based on a minimum concrete compressive strength of approximately 3,000 psi (pounds per square inch).

8.7.7 A thickened edge or integral curb should be constructed on the outside of concrete slabs subjected to wheel loads. The thickened edge should be 1.2 times the slab thickness or a minimum thickness of 2 inches, whichever results in a thicker edge, and taper back to the recommended slab thickness 4 feet behind the face of the slab (e.g., a 7-inch-thick slab would have a 9-inch-thick edge). Reinforcing steel should consist of No. 3 steel bars spaced at 24 inches on center, both directions.

8.7.8 To control the location and spread of concrete shrinkage cracks, crack-control joints (weakened plane joints) should be included in the design of the concrete pavement slab.

Crack-control joints should not exceed 30 times the slab thickness with a maximum spacing of 12.5 feet and 15 feet for the 5.5- and 7-inch-thick slabs, respectively, and should be sealed with an appropriate sealant to prevent the migration of water through the control joint to the subgrade materials. The depth of the crack-control joints should be determined by the referenced ACI report.

Geocon Project No. G2487-32-03 - 20 - December 22, 2022

8.7.9 Concrete curb/gutter should be placed on soil subgrade compacted to a dry density of at least 90 percent of the laboratory maximum dry density near to slightly above optimum moisture content. Cross-gutters should be placed on subgrade soil compacted to a dry density of at least 95 percent of the laboratory maximum dry density near to slightly above optimum moisture content. Base materials should not be placed below the curb/gutter, cross-gutters, or sidewalk so water is not able to migrate from the adjacent parkways to the pavement sections. Where flatwork is located directly adjacent to the curb/gutter, consideration may be given to structurally connecting the concrete flatwork to the curbs to help reduce the potential for offsets between the curbs and the flatwork if differential settlement occurs.

8.8 Conventional Retaining Walls

8.8.1 Retaining walls should be designed using the values presented in Table 8.8.1. Soil with an expansion index (EI) of greater than 50 should not be used as backfill material behind retaining walls.

TABLE 8.8.1

RETAINING WALL DESIGN RECOMMENDATIONS
Parameter ValueP
Active Soil Pressure, A (Fluid Density, Level Backfill) 35 pcf Active Soil Pressure, A (Fluid Density, 2:1 Sloping Backfill) 50 pcf Seismic Pressure, S 16H psf
At-Rest/Restrained Walls Additional Uniform Pressure (0 to 8 Feet High) 8H psf At-Rest/Restrained Walls Additional Uniform Pressure (8+ Feet High) 12H psf Expected Expansion Index for the Subject Property EI<50 H equals the height of the retaining portion of the wall

8.8.2 The project retaining walls should be designed as shown in the Retaining Wall Loading Diagram.

Geocon Project No. G2487-32-03 - 21 - December 22, 2022 Retaining Wall Loading Diagram

8.8.3 Unrestrained walls are those that are allowed to rotate more than 0.001H (where H equals the height of the retaining portion of the wall) at the top of the wall. Where walls are restrained from movement at the top (at-rest condition), an additional uniform pressure should be applied to the wall. For retaining walls subject to vehicular loads within a horizontal distance equal to two-thirds the wall height, a surcharge equivalent to 2 feet of fill soil should be added.

8.8.4 The structural engineer should determine the Seismic Design Category for the project in accordance with Section 1613.3.5 of the 2019 CBC or Section 11.6 of ASCE 7-16. For structures assigned to Seismic Design Category of D, E, or F, retaining walls that support more than 6 feet of backfill should be designed with seismic lateral pressure in accordance with Section 1803.5.12 of the 2019 CBC. The seismic load is dependent on the retained height where H is the height of the wall, in feet, and the calculated loads result in pounds per square foot (psf) exerted at the base of the wall and zero at the top of the wall.

8.8.5 Retaining walls should be designed to ensure stability against overturning sliding, and excessive foundation pressure. Where a keyway is extended below the wall base with the intent to engage passive pressure and enhance sliding stability, it is not necessary to consider active pressure on the keyway.

Geocon Project No. G2487-32-03 - 22 - December 22, 2022

8.8.6 Drainage openings through the base of the wall (weep holes) should not be used where the seepage could be a nuisance or otherwise adversely affect the property adjacent to the base of the wall. The recommendations herein assume a properly compacted granular (EI of 90 or less) free draining backfill material with no hydrostatic forces or imposed surcharge load. The retaining wall should be properly drained as shown in the Typical Retaining Wall Drainage Detail. If conditions different than those described are expected, or if specific drainage details are desired, Geocon Incorporated should be contacted for additional recommendations.

Typical Retaining Wall Drainage Detail

8.8.7 The retaining walls may be designed using either the active and restrained (at-rest) loading condition or the active and seismic loading condition as suggested by the structural engineer.

Typically, it appears the design of the restrained condition for retaining wall loading may be adequate for the seismic design of the retaining walls. However, the active earth pressure combined with the seismic design load should be reviewed and also considered in the design of the retaining walls.

8.8.8 In general, wall foundations should be designed in accordance with Table 8.8.2. The proximity of the foundation to the top of a slope steeper than 3:1 could impact the allowable soil bearing pressure. Therefore, retaining wall foundations should be deepened such that the bottom outside edge of the footing is at least 7 feet horizontally from the face of the slope.

Geocon Project No. G2487-32-03 - 23 - December 22, 2022 TABLE 8.8.2

SUMMARY OF RETAINING WALL FOUNDATION RECOMMENDATIONS
Parameter Value
Minimum Retaining Wall Foundation Width 12 inches
Minimum Retaining Wall Foundation Depth 12 Inches
Minimum Steel Reinforcement Per Structural Engineer
Allowable Bearing Capacity 2,000 psf
Bearing Capacity Increase
500 psf per Foot of Depth
300 psf per Foot of Width
Maximum Allowable Bearing Capacity 4,000 psf
Estimated Total Static Settlement* 1 Inch
Estimated Differential Static Settlement* ½ Inch in 40 Feet

8.8.9 The recommendations presented herein are generally applicable to the design of rigid concrete or masonry retaining walls. In the event that other types of walls (such as mechanically stabilized earth [MSE] walls) are planned, Geocon Incorporated should be consulted for additional recommendations.

8.8.10 Unrestrained walls will move laterally when backfilled and loading is applied. The amount of lateral deflection is dependent on the wall height, the type of soil used for backfill, and loads acting on the wall. The retaining walls and improvements above the retaining walls should be designed to incorporate an appropriate amount of lateral deflection as determined by the structural engineer.

8.8.11 Soil contemplated for use as retaining wall backfill, including import materials, should be identified in the field prior to backfill. At that time, Geocon Incorporated should obtain samples for laboratory testing to evaluate its suitability. Modified lateral earth pressures may be necessary if the backfill soil does not meet the required expansion index or shear strength.

City or regional standard wall designs, if used, are based on a specific active lateral earth pressure and/or soil friction angle. In this regard, on-site soil to be used as backfill may or may not meet the values for standard wall designs. Geocon Incorporated should be consulted to assess the suitability of the on-site soil for use as wall backfill if standard wall designs will be used.

8.9 Lateral Loading

8.9.1 Table 8.9 should be used to help design the proposed structures and improvements to resist lateral loads for the design of footings or shear keys. The allowable passive pressure assumes Geocon Project No. G2487-32-03 - 24 - December 22, 2022 a horizontal surface extending at least 5 feet, or three times the surface generating the passive pressure, whichever is greater. The upper 12 inches of material in areas not protected by floor slabs or pavement should not be included in design for passive resistance.

TABLE 8.9

SUMMARY OF LATERAL LOAD DESIGN RECOMMENDATIONS
Parameter Value
Passive Pressure Fluid Density 300 pcf
Coefficient of Friction (Concrete and Soil) 0.35
Coefficient of Friction (Along Vapor Barrier) 0.2 to 0.25* *Per manufacturer’s recommendations.

8.9.2 The passive and frictional resistant loads can be combined for design purposes. The lateral passive pressures may be increased by one-third when considering transient loads due to wind or seismic forces.

8.10 Site Drainage and Moisture Protection

8.10.1 Adequate site drainage is critical to reduce the potential for differential soil movement, erosion, and subsurface seepage. Under no circumstances should water be allowed to pond adjacent to footings. The site should be graded and maintained such that surface drainage is directed away from structures in accordance with 2019 CBC 1804.3 or other applicable standards. In addition, surface drainage should be directed away from the top of slopes into swales or other controlled drainage devices. Roof and pavement drainage should be directed into conduits that carry runoff away from the proposed structure.

8.10.2 Underground utilities should be leak free. Utility and irrigation lines should be checked periodically for leaks, and detected leaks should be repaired promptly. Detrimental soil movement could occur if water is allowed to infiltrate the soil for prolonged periods of time.

8.11 Grading and Foundation Plan Review

8.11.1 Geocon Incorporated should review the grading and foundation plans for the project prior to final design submittal to determine if additional analysis and/or recommendations are required.

Geocon Project No. G2487-32-03 December 22, 2022

LIMITATIONS AND UNIFORMITY OF CONDITIONS

1. The firm that performed the geotechnical investigation for the project should be retained to provide testing and observation services during construction to provide continuity of geotechnical interpretation and to check that the recommendations presented for geotechnical aspects of site development are incorporated during site grading, construction of improvements, and excavation of foundations. If another geotechnical firm is selected to perform the testing and observation services during construction operations, that firm should prepare a letter indicating their intent to assume the responsibilities of project geotechnical engineer of record.

A copy of the letter should be provided to the regulatory agency for their records. In addition, that firm should provide revised recommendations concerning the geotechnical aspects of the proposed development, or a written acknowledgement of their concurrence with the recommendations presented in our report. They should also perform additional analyses deemed necessary to assume the role of Geotechnical Engineer of Record.

2. The recommendations of this report pertain only to the site investigated and are based upon the assumption that the soil conditions do not deviate from those disclosed in the investigation. If any variations or undesirable conditions are encountered during construction, or if the proposed construction will differ from that anticipated herein, Geocon Incorporated should be notified so that supplemental recommendations can be given. The evaluation or identification of the potential presence of hazardous or corrosive materials was not part of the scope of services provided by Geocon Incorporated.

3. This report is issued with the understanding that it is the responsibility of the owner, or of his representative, to ensure that the information and recommendations contained herein are brought to the attention of the architect and engineer for the project and incorporated into the plans, and that the necessary steps are taken to see that the contractor and subcontractors carry out such recommendations in the field.

4. The findings of this report are valid as of the present date. However, changes in the conditions of a property can occur with the passage of time, whether they are due to natural processes or the works of man on this or adjacent properties. In addition, changes in applicable or appropriate standards may occur, whether they result from legislation or the broadening of knowledge.

Accordingly, the findings of this report may be invalidated wholly or partially by changes outside our control. Therefore, this report is subject to review and should not be relied upon after a period of three years.

W. SAN MARCOS BLVD

SITESITE

NO SCALE
FIG. 1
THE GEOGRAPHICAL INFORMATION MADE AVAILABLE FOR DISPLAY WAS PROVIDED BY GOOGLE EARTH,SUBJECT TO A LICENSING AGREEMENT. THE INFORMATION IS FOR ILLUSTRATIVE PURPOSES ONLY; IT ISNOT INTENDED FOR CLIENT'S USE OR RELIANCE AND SHALL NOT BE REPRODUCED BY CLIENT. CLIENTSHALL INDEMNIFY, DEFEND AND HOLD HARMLESS GEOCON FROM ANY LIABILITY INCURRED AS A RESULTOF SUCH USE OR RELIANCE BY CLIENT.

VICINITY MAP
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974PHONE 858 558-6900 - FAX 858 558-6159DSK/GTYPDPROJECT NO. G2487 - 32 - 03TR / CW

SAN MARCOS RESTAURANT ROWSAN MARCOS, CALIFORNIAGEOTECHNICAL ENVIRONMENTAL MATERIALS Plotted:12/22/2022 8:53AM | By:JONATHAN WILKINS | File Location:Y:\PROJECTS\G2487-32-03 Restaurant Row\DETAILS\G2487-42-03 VicinityMap.dwgDATE 12 - 22 - 2022

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B-6 B-5
B-7 B-4
B-3
B-1
B-2
-8'
-24' -10'
-13'
-17'
-10'
-8'
Qudf
Qudf
Qudf
Qudf
B-6
B-3
B-2
B-1
B-8
B-7
-10'
-17'
-21'
-15'
B-4
5'
3' 3'
9'
9'
4'
5'
5'
4'
5'
4'
5'

EXISTING WELL

LOCATION

FUTURE PARK SITES

FUTURE PARK SITE

PROJECT BOUNDARY

EXISTING FLOODWAY

EXISTING FLOODWAY
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974 PHONE 858 558-6900 - FAX 858 558-6159

SHEET OF
PROJECT NO.

SCALE DATE
FIGURE
Plotted:12/22/2022 9:05AM | By:JONATHAN WILKINS | File Location:Y:\PROJECTS\G2487-32-03 Restaurant Row\SHEETS\G2487-32-03_GeologicMap.dwg

GEOTECHNICAL ENVIRONMENTAL MATERIALS
1" =
GEOLOGIC 1AP

SAN MARCOS RESTAURANT ROW

SAN MARCOS, CALIFORNIA
50' 12 - 22 - 2022
G2487 - 32 - 03
1 1
2 ?
B-7
10'

GEOCON LEGEND
........UNDOCUMENTED FILLQudf
........RECENT EXPLORATORY BORING BY GEOCON (Nov. 2022) ........APPROX. LOCATION OF GEOLOGIC CONTACT
(Dotted Where Buried; Queried Where Uncertain)
........APPROX. THICKNESS OF SURFICIAL DEPOSITS REQUIRING REMEDIAL GRADING (In Feet)
........YOUNGER ALLUVIUM (Dotted Where Buried)Qya
........OLDER ALLUVIUM (Dotted Where Buried)Qoa
B-8
........PREVIOUS EXPLORATORY BORING BY LEIGHTON (Nov. 2014) ........APPROX. DEPTH TO GROUNDWATER (In Feet)
-17'

APPENDIX A
Geocon Project No. G2487-32-03 December 22, 2022

APPENDIX A

FIELD INVESTIGATION
The field investigation was performed on November 7 and 11, 2022, and consisted of a site reconnaissance and the excavation of seven hollow-stem borings (B-1 through B-7). The approximate locations of the borings are shown on the Geologic Map, Figure 2, including the previous borings performed by Leighton, except Boring B-5 which was missing from their report.

The borings were performed by North County Drilling and were advanced to a maximum depth of 41 feet below existing grade using an Ingersoll Rand A-300 drill rig equipped with 6-inch hollow-stem augers. Relatively undisturbed samples were obtained by driving a California split-spoon (CAL) split- tube sampler into the "undisturbed" soil mass. The CAL sampler was equipped with 1-inch by 2⅜-inch, brass sampler rings to facilitate removal and testing. Logs of the borings depicting the soil and geologic conditions encountered and the depth at which samples were obtained are presented on Figures A-1 through A-7. Leighton’s boring logs follow Figure A-7.

The soils encountered in the excavations were visually classified and logged in general accordance with American Society for Testing and Materials (ASTM) practice for Description and Identification of Soils (Visual Manual Procedure D 2488).
2-inches asphalt concrete over 4-inches of decomposed granite (DG)UNDOCUMENTED FILL (Qudf)Medium dense, moist, reddish-brown, Clayey, fine to coarse SANDOLDER ALLUVIUM (Qoa)Medium dense, moist, reddish-brown, Clayey, fine to coarse SAND Dense, moist, reddish-brown to brown, Silty/Clayey, fine to medium SAND Hard, moist, orangish and yellowish-brown, Sandy SILT with clay-Groundwater at 17 feetVery dense, wet, orange, fine, Silty SAND-Becomes fine to coarse SANDHard, wet, dark gray, Clayey SILTTOTAL DEPTH AT 26 FEETGroundwater encountered at 17 feet 121.3
116.9
102.2
107.8

97.0 14.6

15.0 22.1

19.7 24.4
B1-1
B1-2
B1-3
B1-4B1-7B1-5
B1-6
35 91/11"
70 81/10"
50/5"
SCSC
SM
ML
SM
ML
... DISTURBED OR BAG SAMPLE
GEOCON

DEPTHINFEET
02468101214161820222426
Figure A-1,Log of Boring B 1, Page 1 of 1
DRY DENSITY(P.C.F.)
... DRIVE SAMPLE (UNDISTURBED)
IR A-300
PENETRATIONRESISTANCE(BLOWS/FT.)BORING B 1
... CHUNK SAMPLE

DATE COMPLETED
... SAMPLING UNSUCCESSFUL
SOILCLASS(USCS)GROUNDWATERT. MYERS
CONTENT (%)SAMPLENO. 11-07-2022

SAMPLE SYMBOLS
MOISTUREBY:EQUIPMENTELEV. (MSL.)536'
G2487-32-03.GPJ

MATERIAL DESCRIPTION

LITHOLOGY
... STANDARD PENETRATION TEST... WATER TABLE OR... SEEPAGENOTE:

PROJECT NO.

THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. ITIS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.

G2487-32-03
4-inches asphalt concrete over 2-inches of decomposed granite (DG)UNDOCUMENTED FILL (Qudf)Soft, very moist, reddish-brown CLAYOLDER ALLUVIUM (Qoa)Hard, moist, reddish-brown CLAY -Groundwater at 10 feet
Medium dense, wet, reddish-brown and gray, Clayey, fine to medium SAND Very dense, wet, Clayey GRAVEL
Hard, wet, orange, white and gray, Clayey SILT with fine to coarse sand 117.7
105.0
105.9
114.9
113.5

15.8 22.5

20.5 16.4

18.1 B2-1
B2-2B2-3B2-4
B2-5
B2-6
53 62
28 70
75/11"
CLCL
SC
GC
ML
... DISTURBED OR BAG SAMPLE
GEOCON

DEPTHINFEET
0246810121416182022242628Figure A-2,Log of Boring B 2, Page 1 of 2 DRY DENSITY(P.C.F.)
... DRIVE SAMPLE (UNDISTURBED)
IR A-300
PENETRATIONRESISTANCE(BLOWS/FT.)BORING B 2
... CHUNK SAMPLE

DATE COMPLETED
... SAMPLING UNSUCCESSFUL
SOILCLASS(USCS)GROUNDWATERT. MYERS
CONTENT (%)SAMPLENO. 11-07-2022

SAMPLE SYMBOLS
MOISTUREBY:EQUIPMENTELEV. (MSL.)537'
G2487-32-03.GPJ

MATERIAL DESCRIPTION

LITHOLOGY
... STANDARD PENETRATION TEST... WATER TABLE OR... SEEPAGENOTE:

PROJECT NO.

G2487-32-03
-Becomes stiff and dark grayTOTAL DEPTH AT 31 FEETGroundwater encountered at 10 feet97.7 26.4B2-7 33ML ... DISTURBED OR BAG SAMPLE
GEOCON

DEPTHINFEET
30 Figure A-2,Log of Boring B 2, Page 2 of 2
DRY DENSITY(P.C.F.)
... DRIVE SAMPLE (UNDISTURBED)
IR A-300
PENETRATIONRESISTANCE(BLOWS/FT.)BORING B 2
... CHUNK SAMPLE

DATE COMPLETED
... SAMPLING UNSUCCESSFUL
SOILCLASS(USCS)GROUNDWATERT. MYERS
CONTENT (%)SAMPLENO. 11-07-2022

SAMPLE SYMBOLS
MOISTUREBY:EQUIPMENTELEV. (MSL.)537'
G2487-32-03.GPJ

MATERIAL DESCRIPTION

LITHOLOGY
... STANDARD PENETRATION TEST... WATER TABLE OR... SEEPAGENOTE:

PROJECT NO.

G2487-32-03
4-inches asphalt concrete over 7-inches of decomposed granite (DG)UNDOCUMENTED FILL (Qudf)Soft, moist, dark gray, Sandy CLAYOLDER ALLUVIUM (Qoa)Hard, damp, dark brown, Sandy SILT with clayDense, moist, dark yellowish-brown, Silty, fine to coarse SAND -Groundwater encountered at 13 feetStiff, wet, orange, white, gray, Clayey SILT -Becomes very stiff and dark gray at 20 feet
Hard, wet, yellowish-brown, Silty CLAY
Very dense, wet, dark gray, Silty, fine to coarse SAND
109.3
109.8

95.5 91.2

93.6 16.2

29.6 28.1

29.8 29.3
B3-1
B3-2
B3-3
B3-4
B3-5
92/9"
41 23
47 50/5"
CLML
SM
ML
CL
SM
... DISTURBED OR BAG SAMPLE
GEOCON

DEPTHINFEET
0246810121416182022242628Figure A-3,Log of Boring B 3, Page 1 of 2 DRY DENSITY(P.C.F.)
... DRIVE SAMPLE (UNDISTURBED)
IR A-300
PENETRATIONRESISTANCE(BLOWS/FT.)BORING B 3
... CHUNK SAMPLE

DATE COMPLETED
... SAMPLING UNSUCCESSFUL
SOILCLASS(USCS)GROUNDWATERT. MYERS
CONTENT (%)SAMPLENO. 11-07-2022

SAMPLE SYMBOLS
MOISTUREBY:EQUIPMENTELEV. (MSL.)533'
G2487-32-03.GPJ

MATERIAL DESCRIPTION

LITHOLOGY
... STANDARD PENETRATION TEST... WATER TABLE OR... SEEPAGENOTE:

PROJECT NO.

G2487-32-03
TOTAL DEPTH AT 41 FEETGroundwater encountered at 13 feet 107.5
100.6
108.0

19.4 21.9

18.8 B3-6
B3-7
B3-8
50/5"
50/4"
50/3"
SM
... DISTURBED OR BAG SAMPLE
GEOCON

DEPTHINFEET
303234363840
Figure A-3,Log of Boring B 3, Page 2 of 2
DRY DENSITY(P.C.F.)
... DRIVE SAMPLE (UNDISTURBED)
IR A-300
PENETRATIONRESISTANCE(BLOWS/FT.)BORING B 3
... CHUNK SAMPLE

DATE COMPLETED
... SAMPLING UNSUCCESSFUL
SOILCLASS(USCS)GROUNDWATERT. MYERS
CONTENT (%)SAMPLENO. 11-07-2022

SAMPLE SYMBOLS
MOISTUREBY:EQUIPMENTELEV. (MSL.)533'
G2487-32-03.GPJ

MATERIAL DESCRIPTION

LITHOLOGY
... STANDARD PENETRATION TEST... WATER TABLE OR... SEEPAGENOTE:

PROJECT NO.

G2487-32-03
2-inches asphalt concrete over 5-inches of decomposed granite (DG)UNDOCUMENTED FILL (Qudf)Medium dense, damp, grayish-brown, Silty, fine to coarse SANDYOUNG ALLUVIUM (Qya)Stiff, very moist to wet, dark gray, Sandy CLAY OLDER ALLUVIUM (Qoa)Medium dense, wet, light brown, Silty, fine to coarse SAND-Groundwater encountered at 10 feet -Becomes dense and orange white at 15 feet
-Becomes yellowish brown and white at 20 feetVery stiff, wet, dark gray, Sandy SILTVery dense, wet, yellowish-brown, Silty, fine to coarse SAND 103.7
120.5
111.8
108.7
112.6

22.9 15.5

16.7 18.9

19.6 B4-1B4-2B4-3
B4-4
B4-5
B4-6
15 23
70 76
50/5"
SMCL
SM
MLSM
... DISTURBED OR BAG SAMPLE
GEOCON

DEPTHINFEET
0246810121416182022242628Figure A-4,Log of Boring B 4, Page 1 of 2 DRY DENSITY(P.C.F.)
... DRIVE SAMPLE (UNDISTURBED)
IR A-300
PENETRATIONRESISTANCE(BLOWS/FT.)BORING B 4
... CHUNK SAMPLE

DATE COMPLETED
... SAMPLING UNSUCCESSFUL
SOILCLASS(USCS)GROUNDWATERT. MYERS
CONTENT (%)SAMPLENO. 11-07-2022

SAMPLE SYMBOLS
MOISTUREBY:EQUIPMENTELEV. (MSL.)531'
G2487-32-03.GPJ

MATERIAL DESCRIPTION

LITHOLOGY
... STANDARD PENETRATION TEST... WATER TABLE OR... SEEPAGENOTE:

PROJECT NO.

G2487-32-03
-Becomes gray at 30 feet
TOTAL DEPTH AT 36 FEETGroundwater encountered at 10 feet 108.1
115.1

19.2 16.8
B4-7
B4-8
50/4"
50/4"
SM
... DISTURBED OR BAG SAMPLE
GEOCON

DEPTHINFEET
30323436
Figure A-4,Log of Boring B 4, Page 2 of 2
DRY DENSITY(P.C.F.)
... DRIVE SAMPLE (UNDISTURBED)
IR A-300
PENETRATIONRESISTANCE(BLOWS/FT.)BORING B 4
... CHUNK SAMPLE

DATE COMPLETED
... SAMPLING UNSUCCESSFUL
SOILCLASS(USCS)GROUNDWATERT. MYERS
CONTENT (%)SAMPLENO. 11-07-2022

SAMPLE SYMBOLS
MOISTUREBY:EQUIPMENTELEV. (MSL.)531'
G2487-32-03.GPJ

MATERIAL DESCRIPTION

LITHOLOGY
... STANDARD PENETRATION TEST... WATER TABLE OR... SEEPAGENOTE:

PROJECT NO.

G2487-32-03
3-inches of asphalt concrete over 9-inches of decomposed granite (DG)UNDOCUMENTED FILL (Qudf)Medium dense, moist, dark gray, Silty/Clayey, fine to medium SANDOLDER ALLUVIUM (Qoa)Stiff, moist, dark gray, Sandy SILT with clay -Groundwater at 8 feet-No recovery
-No recoveryGravel layer (based on chatter from drill rig)-No recoveryTOTAL DEPTH AT 21 FEETGroundwater encountered at 8 feet 115.6 15.4B5-1B5-2
B5-3
B5-4
B5-5
28 24
17 50/4"

SM-SCML
... DISTURBED OR BAG SAMPLE
GEOCON

DEPTHINFEET
02468101214161820
Figure A-5,Log of Boring B 5, Page 1 of 1
DRY DENSITY(P.C.F.)
... DRIVE SAMPLE (UNDISTURBED)
IR A-300
PENETRATIONRESISTANCE(BLOWS/FT.)BORING B 5
... CHUNK SAMPLE

DATE COMPLETED
... SAMPLING UNSUCCESSFUL
SOILCLASS(USCS)GROUNDWATERT. MYERS
CONTENT (%)SAMPLENO. 11-11-2022

SAMPLE SYMBOLS
MOISTUREBY:EQUIPMENTELEV. (MSL.)529'
G2487-32-03.GPJ

MATERIAL DESCRIPTION

LITHOLOGY
... STANDARD PENETRATION TEST... WATER TABLE OR... SEEPAGENOTE:

PROJECT NO.

G2487-32-03
3-inches asphalt concrete over 9-inches of decomposed granite (DG)UNDOCUMENTED FILL (Qudf)Medium dense, moist, dark gray Silty/Clayey, fine to medium SANDOLDER ALLUVIUM (Qoa)Very stiff, moist, dark gray, Sandy CLAY -Groundwater at 8 feet-Becomes gray-brown and orange-brown with interbedded clayey, fine tomedium sandMedium dense, wet, gray Clayey, fine to medium SAND Very dense, wet, orange and white, Silty, fine to coarse SAND -Becomes gray at 26 feet
111.2
111.2
111.0
111.9
110.2

16.5 18.1

18.4 16.4

17.2 B6-1
B6-2B6-3
B6-4
B6-5
B6-6
33 27
23 50/3"
50/3"

SM/SCCL
SC
SM
... DISTURBED OR BAG SAMPLE
GEOCON

DEPTHINFEET
0246810121416182022242628Figure A-6,Log of Boring B 6, Page 1 of 2 DRY DENSITY(P.C.F.)
... DRIVE SAMPLE (UNDISTURBED)
IR A-300
PENETRATIONRESISTANCE(BLOWS/FT.)BORING B 6
... CHUNK SAMPLE

DATE COMPLETED
... SAMPLING UNSUCCESSFUL
SOILCLASS(USCS)GROUNDWATERT. MYERS
CONTENT (%)SAMPLENO. 11-11-2022

SAMPLE SYMBOLS
MOISTUREBY:EQUIPMENTELEV. (MSL.)529'
G2487-32-03.GPJ

MATERIAL DESCRIPTION

LITHOLOGY
... STANDARD PENETRATION TEST... WATER TABLE OR... SEEPAGENOTE:

PROJECT NO.

G2487-32-03
-Becomes dark gray and silty/clayey, fine to coarse sand at 30 feet TOTAL DEPTH AT 36 FEETGroundwater encountered at 8 feet 107.7
111.1

18.5 17.8
B6-7
B6-8
50/3"
50/3"
SM
... DISTURBED OR BAG SAMPLE
GEOCON

DEPTHINFEET
30323436
Figure A-6,Log of Boring B 6, Page 2 of 2
DRY DENSITY(P.C.F.)
... DRIVE SAMPLE (UNDISTURBED)
IR A-300
PENETRATIONRESISTANCE(BLOWS/FT.)BORING B 6
... CHUNK SAMPLE

DATE COMPLETED
... SAMPLING UNSUCCESSFUL
SOILCLASS(USCS)GROUNDWATERT. MYERS
CONTENT (%)SAMPLENO. 11-11-2022

SAMPLE SYMBOLS
MOISTUREBY:EQUIPMENTELEV. (MSL.)529'
G2487-32-03.GPJ

MATERIAL DESCRIPTION

LITHOLOGY
... STANDARD PENETRATION TEST... WATER TABLE OR... SEEPAGENOTE:

PROJECT NO.

G2487-32-03
UNDOCUMENTED FILL (Qudf)Loose to medium dense, damp, orange-brown, Silty, fine to medium SAND OLDER ALLUVIUM (Qoa)Very dense, damp, reddish brown, Silty to Clayey, fine to coarse SANDVery stiff, moist, dark yellowish-brown to reddish-brown, Clayey SILT Dense, damp to moist, white, Silty, fine to medium SAND-Becomes orange at 17 feetVery stiff, moist to very moist, orange and red, fine, Silty CLAYVery dense, very moist, brown, Silty, fine to medium SAND-Groundwater at 24 feetVery dense, wet, dark gray, Clayey, fine to medium SAND 113.4
103.3

87.8 97.9
109.3

15.2 22.3

34.0 24.7

15.8 B7-1B7-2
B7-3B7-4B7-5
B7-6
B7-7
50/5"
48 52
48 50/5"
SM
SM
ML
SM
CLSM
SC
... DISTURBED OR BAG SAMPLE
GEOCON

DEPTHINFEET
0246810121416182022242628Figure A-7,Log of Boring B 7, Page 1 of 2 DRY DENSITY(P.C.F.)
... DRIVE SAMPLE (UNDISTURBED)
IR A-300
PENETRATIONRESISTANCE(BLOWS/FT.)BORING B 7
... CHUNK SAMPLE

DATE COMPLETED
... SAMPLING UNSUCCESSFUL
SOILCLASS(USCS)GROUNDWATERT. MYERS
CONTENT (%)SAMPLENO. 11-11-2022

SAMPLE SYMBOLS
MOISTUREBY:EQUIPMENTELEV. (MSL.)532'
G2487-32-03.GPJ

MATERIAL DESCRIPTION

LITHOLOGY
... STANDARD PENETRATION TEST... WATER TABLE OR... SEEPAGENOTE:

PROJECT NO.

G2487-32-03
Very dense, very moist, dark gray, Silty, fine to medium SAND Very dense, very moist, dark gray, Silty/Clayey, fine to medium SAND-No recovery TOTAL DEPTH AT 41 FEETGroundwater encountered at 24 feet 101.5 13.6B7-8
B7-9
50/3"
50/3"
50/3"
SM
SM/SC
... DISTURBED OR BAG SAMPLE
GEOCON

DEPTHINFEET
303234363840
Figure A-7,Log of Boring B 7, Page 2 of 2
DRY DENSITY(P.C.F.)
... DRIVE SAMPLE (UNDISTURBED)
IR A-300
PENETRATIONRESISTANCE(BLOWS/FT.)BORING B 7
... CHUNK SAMPLE

DATE COMPLETED
... SAMPLING UNSUCCESSFUL
SOILCLASS(USCS)GROUNDWATERT. MYERS
CONTENT (%)SAMPLENO. 11-11-2022

SAMPLE SYMBOLS
MOISTUREBY:EQUIPMENTELEV. (MSL.)532'
G2487-32-03.GPJ

MATERIAL DESCRIPTION

LITHOLOGY
... STANDARD PENETRATION TEST... WATER TABLE OR... SEEPAGENOTE:

PROJECT NO.

G2487-32-03

APPENDIX B
Geocon Project No. G2487-32-03 December 22, 2022

APPENDIX B

LABORATORY TESTING
Laboratory tests were performed in accordance with generally accepted test methods of the American Society for Testing and Materials (ASTM) or other suggested procedures. Selected soil samples were tested for their in-place dry density and moisture content, expansion potential, soluble sulfate content, and consolidation. The in-place dry density and moisture content results are indicated on the exploratory boring logs. The results of our laboratory tests are summarized on Tables B-I and B-II and the following figures.

TABLE B-I

SUMMARY OF LABORATORY EXPANSION INDEX TEST RESULTS
ASTM D 4829
Sample No.

Moisture Content
Dry Density (pcf) Expansion Index
Before Test (%) After Test (%)
B1-1 8.5 16.1 116.1 29
B4-2 11.8 24.6 103.8 54
B7-1 10.0 19.2 110.4 35

TABLE B-II

SUMMARY OF LABORATORY WATER SOLUBLE SULFATE TEST RESULTS CALIFORNIA TEST NO. 417
Sample No. Water Soluble Sulfate (%)
B1-1 0.007
B4-2 0.008
B7-1 0.012
SAMPLE NO.: Qoa
SAMPLE DEPTH (FT):

B1-2
5 GEOLOGIC UNIT:

TEST INFORMATION
121.3
PROJECT NO.: G2487-32-03

14.6%
INITIAL DRY DENSITY (PCF):

INITIAL WATER CONTENT (%):

SAMPLE SATURATED AT (KSF):

INITIAL SATURATION (%):
.5
100+
CONSOLIDATION CURVE - ASTM D 2435

RESTAURANT ROW
‐2.0

0.0 2.0

4.0 6.0

8.0 10.0

0.10 1.00 10.00
VERTICAL STRAIN (%)
APPLIED PRESSURE (KSF)

SAMPLE NO.: Qoa
SAMPLE DEPTH (FT):

B1-3
10 GEOLOGIC UNIT:

TEST INFORMATION
116.9
PROJECT NO.: G2487-32-03

15.0%
INITIAL DRY DENSITY (PCF):

INITIAL WATER CONTENT (%):

SAMPLE SATURATED AT (KSF):

INITIAL SATURATION (%):

1.0 94.9%
CONSOLIDATION CURVE - ASTM D 2435

RESTAURANT ROW
‐2.0

0.0 2.0

4.0 6.0

8.0 10.0

0.10 1.00 10.00
VERTICAL STRAIN (%)
APPLIED PRESSURE (KSF)

SAMPLE NO.: Qoa
SAMPLE DEPTH (FT):

B1-5
20 GEOLOGIC UNIT:

TEST INFORMATION
107.8
PROJECT NO.: G2487-32-03

19.7%
INITIAL DRY DENSITY (PCF):

INITIAL WATER CONTENT (%):

SAMPLE SATURATED AT (KSF):

INITIAL SATURATION (%):

1.0 97.4%
CONSOLIDATION CURVE - ASTM D 2435

REASTAURANT ROW
‐2.0

0.0 2.0

4.0 6.0

8.0 10.0

0.10 1.00 10.00
VERTICAL STRAIN (%)
APPLIED PRESSURE (KSF)

SAMPLE NO.: Qoa
SAMPLE DEPTH (FT):

B2-1
5 GEOLOGIC UNIT:

TEST INFORMATION
117.7
PROJECT NO.: G2487-32-03

15.8%
INITIAL DRY DENSITY (PCF):

INITIAL WATER CONTENT (%):

SAMPLE SATURATED AT (KSF):

INITIAL SATURATION (%):
.5
100+
CONSOLIDATION CURVE - ASTM D 2435

RESTAURAND ROW
‐2.0

0.0 2.0

4.0 6.0

8.0 10.0

0.10 1.00 10.00
VERTICAL STRAIN (%)
APPLIED PRESSURE (KSF)

SAMPLE NO.: Qoa
SAMPLE DEPTH (FT):

B2-2
10 GEOLOGIC UNIT:

TEST INFORMATION
105.0
PROJECT NO.: G2487-32-03

22.5%
INITIAL DRY DENSITY (PCF):

INITIAL WATER CONTENT (%):

SAMPLE SATURATED AT (KSF):

INITIAL SATURATION (%):

1.0 100+
CONSOLIDATION CURVE - ASTM D 2435

RESTAURAND ROW
‐2.0

0.0 2.0

4.0 6.0

8.0 10.0

0.10 1.00 10.00
VERTICAL STRAIN (%)
APPLIED PRESSURE (KSF)

SAMPLE NO.: Qoa
SAMPLE DEPTH (FT):

B2-4
15 GEOLOGIC UNIT:

TEST INFORMATION
105.9
PROJECT NO.: G2487-32-03

20.5%
INITIAL DRY DENSITY (PCF):

INITIAL WATER CONTENT (%):

SAMPLE SATURATED AT (KSF):

INITIAL SATURATION (%):

1.0 96.2%
CONSOLIDATION CURVE - ASTM D 2435

RESTAURAND ROW
‐2.0

0.0 2.0

4.0 6.0

8.0 10.0

0.10 1.00 10.00
VERTICAL STRAIN (%)
APPLIED PRESSURE (KSF)

SAMPLE NO.: Qoa
SAMPLE DEPTH (FT):

B2-6
25 GEOLOGIC UNIT:

TEST INFORMATION
113.5
PROJECT NO.: G2487-32-03

18.1%
INITIAL DRY DENSITY (PCF):

INITIAL WATER CONTENT (%):

SAMPLE SATURATED AT (KSF):

INITIAL SATURATION (%):

1.0 100+
CONSOLIDATION CURVE - ASTM D 2435

REASTAURANT ROW
‐2.0

0.0 2.0

4.0 6.0

8.0 10.0

0.10 1.00 10.00
VERTICAL STRAIN (%)
APPLIED PRESSURE (KSF)

SAMPLE NO.: Qoa
SAMPLE DEPTH (FT):

B3-1
5 GEOLOGIC UNIT:

TEST INFORMATION
109.3
PROJECT NO.: G2487-32-03

16.2%
INITIAL DRY DENSITY (PCF):

INITIAL WATER CONTENT (%):

SAMPLE SATURATED AT (KSF):

INITIAL SATURATION (%):
.5

83.3%
CONSOLIDATION CURVE - ASTM D 2435

RESTAURANT ROW
‐2.0

0.0 2.0

4.0 6.0

8.0 10.0

0.10 1.00 10.00
VERTICAL STRAIN (%)
APPLIED PRESSURE (KSF)

SAMPLE NO.: Qoa
SAMPLE DEPTH (FT):

B3-2
10 GEOLOGIC UNIT:

TEST INFORMATION
109.8
PROJECT NO.: G2487-32-03

20.6%
INITIAL DRY DENSITY (PCF):

INITIAL WATER CONTENT (%):

SAMPLE SATURATED AT (KSF):

INITIAL SATURATION (%):

1.0 100+
CONSOLIDATION CURVE - ASTM D 2435

REASTAURANT ROW
‐2.0

0.0 2.0

4.0 6.0

8.0 10.0

0.10 1.00 10.00
VERTICAL STRAIN (%)
APPLIED PRESSURE (KSF)

SAMPLE NO.: Qoa
SAMPLE DEPTH (FT):

B3-3
15 GEOLOGIC UNIT:

TEST INFORMATION

95.5 PROJECT NO.: G2487-32-03

28.1%
INITIAL DRY DENSITY (PCF):

INITIAL WATER CONTENT (%):

SAMPLE SATURATED AT (KSF):

INITIAL SATURATION (%):

1.0 100+
CONSOLIDATION CURVE - ASTM D 2435

RESTAURANT ROW
‐2.0

0.0 2.0

4.0 6.0

8.0 10.0

0.10 1.00 10.00
VERTICAL STRAIN (%)
APPLIED PRESSURE (KSF)

SAMPLE NO.: Qya
SAMPLE DEPTH (FT):

B4-1
5 GEOLOGIC UNIT:

TEST INFORMATION
103.7
PROJECT NO.: G2487-32-03

22.9%
INITIAL DRY DENSITY (PCF):

INITIAL WATER CONTENT (%):

SAMPLE SATURATED AT (KSF):

INITIAL SATURATION (%):
.5
100+
CONSOLIDATION CURVE - ASTM D 2435

RESTAURANT ROW
‐2.0

0.0 2.0

4.0 6.0

8.0 10.0

0.10 1.00 10.00
VERTICAL STRAIN (%)
APPLIED PRESSURE (KSF)

APPENDIX C

STORM WATER MANAGEMENT INVESTIGATION
FOR

SAN MARCOS RESTAURANT ROW

SAN MARCOS, CALIFORNIA
PROJECT NO. G2487-32-03
Geocon Project No. G2487-32-03 - C-1 - December 22, 2022

APPENDIX C

STORM WATER MANAGEMENT INVESTIGATION
We understand storm water management devices are being proposed in accordance with the 2016 City of San Marcos BMP Design Manual, commonly referred to as the Storm Water Standards (SWS). If not properly constructed, there is a potential for distress to improvements and properties located hydrologically down gradient or adjacent to these devices. Factors such as the amount of water to be detained, its residence time, and soil permeability have an important effect on seepage transmission and the potential adverse impacts that may occur if the storm water management features are not properly designed and constructed.

We have not performed a hydrogeological study at the site. If infiltration of storm water runoff occurs, downstream properties may be subjected to seeps, springs, slope instability, raised groundwater, movement of foundations and slabs, or other undesirable impacts as a result of water infiltration.

Hydrologic Soil Group
The United States Department of Agriculture (USDA), Natural Resources Conservation Services (NRCS), possesses general information regarding the existing soil conditions for areas within the United States. The USDA NRCS website also provides the Hydrologic Soil Group. Table C-1 presents the descriptions of the hydrologic soil groups. In addition, the USDA website also provides an estimated saturated hydraulic conductivity for the existing soil.

TABLE C-1

HYDROLOGIC SOIL GROUP DEFINITIONS
Soil Group Soil Group Definition
A
Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission.

B
Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission.

C
Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission.

D
Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high-water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission.

The property is underlain by four units identified as Placentia sandy loam (PaE, PeC and PfA), and Ramona sandy loam (RaB) . The Placentia and Ramona sandy loams are classified as Soil Groups C and D. Table C-2 presents the information from the USDA NRCS website for the subject property.

Geocon Project No. G2487-32-03 - C-2 - December 22, 2022 TABLE C-2
USDA WEB SOIL SURVEY – HYDROLOGIC SOIL GROUP
Map Unit Name Map Unit
Symbol
Approximate
Percentage
of Property
Hydrologic
Soil Group
kSAT of Most
Limiting Layer
(inches/hour)
Placentia sandy loam PeA 3 C 0.06 – 0.60
Placentia sandy loam PeC 61 C 0.06 – 0.60
Placentia sandy loam PfA 35 D 0.00 – 0.06
Ramona sandy loam RaB 1 C 0.20 – 0.57

STORM WATER MANAGEMENT CONCLUSIONS
The Geologic Map, Figure 2, depicts the existing property, proposed development, the approximate lateral limits of the geologic units, and locations of the recent and previous exploratory borings.

Soil Types
Proposed Compacted Fill – Compacted fill will be placed across the entire property during site development. Proposed remedial grading will consist of removing the upper 3 to 9 feet of soil and replacement as compacted fill. The proposed storm water BMP’s will be founded in compacted fill placed above older alluvium. The compacted fill will be comprised of on-site clays which exhibit very low infiltration rates not suitable for infiltration BMP’s. The fill will be compacted to a dry density of at least 90 percent of the laboratory maximum dry density. In our experience, compacted fill does not possess infiltration rates appropriate for infiltration BMP’s. Hazards that occur as a result of fill soil saturation include a potential for hydro-consolidation of the granular fill soils, long term fill settlement, differential fill settlement, heaving of expansive clay soil, and lateral movement associated with saturated fill relaxation. The potential for lateral water migration to adversely impact existing or proposed structures, foundations, utilities, and roadways, is high. Therefore, full infiltration should be considered infeasible.

Section D.4.2 of the 2016 Storm Water Standards (SWS) provides a discussion regarding fill materials used for infiltration. The SWS states:
 For engineered fills, infiltration rates may still be quite uncertain due to layering and heterogeneities introduced as part of construction that cannot be precisely controlled. Due to these uncertainties, full and partial infiltration should be considered geotechnically infeasible and liners and subdrains should be used in areas where infiltration BMP’s are founded in compacted fill.
 Where possible, infiltration BMPs on fill material should be designed such that their infiltrating surface extends into native soils. The underlying older alluvium below the compacted fill is expected to be approximately 5 to 10 feet below existing grade. Full and partial infiltration Geocon Project No. G2487-32-03 - C-3 - December 22, 2022 should be considered geotechnically infeasible within the compacted fill and liners and subdrains should be used. If the infiltration BMP’s extended below the compacted fill, partial infiltration may be feasible if the infiltration BMP extends below the compacted fill.  Because of the uncertainty of fill parameters as well as potential compaction of the native soils, an infiltration BMP may not be feasible. Therefore, full infiltration should be considered geotechnically infeasible. Partial infiltration may be feasible if the infiltration BMP extends below the compacted fill.

Older Alluvium – Older alluvium will underlie the compacted fill, which consists of medium dense to very dense, silty/clayey sand and hard, sandy silt and clay. The infiltration rates in the older alluvial deposits typically exhibit very poor permeability characteristics, which do not support full or partial infiltration.

Groundwater Elevations
Groundwater was encountered approximately 8 to 24 feet below existing grades. Groundwater is not anticipated to significantly impact project development as presently proposed. Proper surface drainage of irrigation and rainwater will be important to future performance of the project.

Soil or Groundwater Contamination
Based on our review of the Geotracker website, no soil or groundwater contamination is suspected.

New or Existing Utilities
Existing utilities are present within right of ways adjacent to the existing streets, generally beneath public sidewalks and roadways. We expect that all on-site utilities will be removed prior to site development.

Full infiltration near existing or proposed utilities should be avoided to prevent lateral water migration into the permeable trench backfill materials.

Existing and Planned Structures
Commercial developments currently surround the property and are in close proximity to the property boundaries. If water is allowed to infiltrate into the soil, the water could potentially migrate laterally and into other properties in the vicinity of the subject site. The water migration may negatively affect other buildings and improvements in the area.

Slopes
Infiltration BMP’s situated in close proximity to descending fill slopes are not recommended due to the potential for daylight water seepage and lateral water migration.

Geocon Project No. G2487-32-03 - C-4 - December 22, 2022 Recommendations
Due to the very low infiltration rates expected for the clayey older alluvial deposits, and close proximity to public and private improvements, foundations, and roadways, full and partial infiltration of storm water is considered geotechnically infeasible. Liners and subdrains should be incorporated into the design and construction of the planned storm water devices. The liners should be impermeable (e.g.

High-density polyethylene, HDPE, with a thickness of about 30 mil or equivalent Polyvinyl Chloride, PVC) to prevent water migration. The subdrains should be perforated within the liner area, installed at the base and above the liner, be at least 4 inches in diameter and consist of Schedule 40 PVC pipe. The subdrains outside of the liner should consist of solid pipe. Seams and penetrations of the liners should be properly waterproofed. The subdrains should be connected to a proper outlet. The devices should also be installed in accordance with the manufacturer’s recommendations.

Storm Water Standard Worksheets
The SWS requests the geotechnical engineer complete the Categorization of Infiltration Feasibility Condition (Worksheet C.4-1 or I-8) worksheet information to help evaluate the potential for infiltration on the property. The attached Form 1-8 presents the completed information for the submittal process.

The regional storm water standards also have a worksheet (Worksheet D.5-1 or Form I-9) that helps the project civil engineer estimate the factor of safety based on several factors. Table C-3 describes the suitability assessment input parameters related to the geotechnical engineering aspects for the factor of safety determination.

TABLE C-3

SUITABILITY ASSESSMENT RELATED CONSIDERATIONS

FOR INFILTRATION FACILITY SAFETY FACTORS
Consideration High
Concern – 3 Points
Medium
Concern – 2 Points
Low
Concern – 1 Point
Assessment Methods
Use of soil survey maps
or simple texture analysis
to estimate short-term
infiltration rates. Use of
well permeameter or
borehole methods without
accompanying continuous
boring log. Relatively
sparse testing with direct
infiltration methods
Use of well permeameter
or borehole methods with
accompanying continuous
boring log. Direct
measurement of
infiltration area with
localized infiltration
measurement methods
(e.g., Infiltrometer).

Moderate spatial
resolution
Direct measurement
with localized
(i.e. small-scale)
infiltration testing
methods at relatively
high resolution or use
of extensive test pit
infiltration
measurement
methods.

Predominant Soil Texture Silty and clayey soils
with significant fines Loamy soils Granular to slightly loamy soils
Site Soil Variability
Highly variable soils
indicated from site
assessment or unknown
variability
Soil boring/test pits
indicate moderately
homogenous soils
Soil boring/test pits
indicate relatively
homogenous soils
Depth to Groundwater/
Impervious Layer
<5 feet below
facility bottom
5-15 feet below
facility bottom
>15 feet below
facility bottom
Geocon Project No. G2487-32-03 - C-5 - December 22, 2022 Based on our geotechnical investigation and the information in Table C-3, Table C-4 presents the estimated factor values for the evaluation of the factor of safety. This table only provides the suitability assessment safety factor (Part A) of the worksheet. The project civil engineer should evaluate the safety factor for design (Part B) and use the combined safety factor for the design infiltration rate.

TABLE C-4
FACTOR OF SAFETY WORKSHEET DESIGN VALUES – PART A1
Suitability Assessment Factor Category Assigned
Weight (w)
Factor
Value (v)
Product
(p = w x v)
Assessment Methods 0.25 3 0.75
Predominant Soil Texture 0.25 3 0.75
Site Soil Variability 0.25 2 0.50
Depth to Groundwater/ Impervious Layer 0.25 2 0.50
Suitability Assessment Safety Factor, SA = ∑p 2.50
1 The project civil engineer should complete Worksheet D.5-1 or Form I-9 using the data on this table. Additional information is required to evaluate the design factor of safety.

February 2016

Categorization of Infiltration Feasibility Condition Form I-8

Part 1 - Full Infiltration Feasibility Screening Criteria Would infiltration of the full design volume be feasible from a physical perspective without any undesirable consequences that cannot be reasonably mitigated?
Criteria Screening Question Yes No

1 Is the estimated reliable infiltration rate below proposed facility locations greater than 0.5 inches per hour? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2 and Appendix D.

Provide basis:

Based on the results of previous infiltration testing by others, the in-situ infiltration rates in two locations and using the Porchet Method to convert percolation rate to infiltration rate, were less than 0.02 and 0.01 inches per hour (iph).

After applying a feasibility factor of safety of 2, the design infiltration rates are less than 0.01 iph. In addition, the USDA NRCS web soil survey indicates the proposed BMP’s are located in soil belonging to Hydrologic Soil Group D with anticipated rates of 0.0 to 0.06 iph, which are not conducive to infiltration.

Based on the infiltration rates, full infiltration is infeasible.

2 Can infiltration greater than 0.5 inches per hour be allowed without increasing risk of geotechnical hazards (slope stability, groundwater mounding, utilities, or other factors) that cannot be mitigated to an acceptable level? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2.

Provide basis:

If water is allowed to infiltrate into the underlying highly expansive soils, there is an increased risk for heaving and soil movement that could adversel y impact nearby structures and improvements. The potential for groundwater mounding exists. Groundwater is located between 10 to 20 feet below existing grades.

February 2016

Form I-8 Page 2 of 4
Criteria Screening Question Yes No

3 Can infiltration greater than 0.5 inches per hour be allowed without increasing risk of groundwater contamination (shallow water table, storm water pollutants or other factors) that cannot be mitigated to an acceptable level? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3.

Provide basis:

Groundwater is located approximately 10 to 20 feet from the ground surface. No contamination is suspected based on review of the Storm Water Standards Manual and Geotracker website. Per the SWS Manual, infiltration BMP’s should be located at least 10 feet from groundwater if the groundwater is considered of beneficial use.

4 Can infiltration greater than 0.5 inches per hour be allowed without causing potential water balance issues such as change of seasonality of ephemeral streams or increased discharge of contaminated groundwater to surface waters? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3.

Provide basis:

We do not expect infiltration will cause water balance issues such as seasonality of ephemeral streams or increased discharge of contaminated groundwater to surface waters. However, evaluating water balance issues is beyond the scope of the geotechnical engineer and should be evaluated by others.

Part 1
Result
*
If all answers to rows 1 - 4 are “Yes” a full infiltration design is potentially feasible. The feasibility screening category is Full Infiltration

If any answer from row 1-4 is “No”, infiltration may be possible to some extent but would not generally be feasible or desirable to achieve a “full infiltration” design.

Proceed to Part 2

No
*To be completed using gathered site information and best professional judgment considering the definition of MEP in the MS4 Permit. Additional testing and/or studies may be required by Agency/Jurisdictions to substantiate findings

February 2016

Form I-8 Page 3 of 4

Part 2 – Partial Infiltration vs. No Infiltration Feasibility Screening Criteria

Would infiltration of water in any appreciable am ount be physically feasible without any negative consequences that cannot be reasonably mitigated?
Criteria Screening Question Yes No

5 Do soil and geologic conditions allow for infiltration in any appreciable rate or volume? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2 and Appendix D.

Provide basis:

After applying a feasibility factor of safety of 2, the design infiltration rates are less than 0.01 iph. A design infiltration rate of 0.05 iph is considered necessary to consider partial infiltration. In addition, the USDA NRCS web soil survey indicates the proposed BMP’s are located in soil belonging to Hydrologic Soil Group D with anticipated rates of 0.0 to 0.06 iph, which are not conducive to infiltration.

Based on the infiltration rates, partial infiltration is considered infeasible.

6 Can Infiltration in any appreciable quantity be allowed without increasing risk of geotechnical hazards (slope stability, groundwater mounding, utilities, or other factors) that cannot be mitigated to an acceptable level? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2.

Provide basis:

If water is allowed to infiltrate into the underlying highly expansive soils, there is an increased risk for heaving and soil movement that could adversely impact nearby structures and improvements. The potential for groundwater mounding exists. Groundwater is located between 10 to 20 feet below existing grades.

February 2016

Form I-8 Page 4 of 4
Criteria Screening Question Yes No

7 Can Infiltration in any appreciable quantity be allowed without posing significant risk for groundwater related concerns (shallow water table, storm water pollutants or other factors)? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3.

Provide basis:

8 Can infiltration be allowed without violating downstream water rights? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3.

Provide basis:

We do not expect infiltration to violate downstream water right s, however, evaluating water rights is not a geotechnical issue and should be evaluated by others.

Part 2
Result*

If all answers from row 5-8 are yes then partia l infiltration design is potentially feasible.

The feasibility screening category is Partial Infiltration.

If any answer from row 5-8 is no, then infi ltration of any volume is considered to be infeasible within the drainage area. The feasibility screening category is No Infiltration.

No Infiltration

*To be completed using gathered site information and best professional judgment considering the definition of MEP in the MS4 Permit. Additional testing and/or studies may be required by Agency/Jurisdictions to substantiate findings PVT. DR. "A"
PVT. DR. "A"
BLDG. NO. 11
BLDG. NO. 10
COMMON
AREA

CITY OF SAN MARCOS

RESTAURANT ROW
United States
Department of
Agriculture
A product of the National
Cooperative Soil Survey,
a joint effort of the United
States Department of
Agriculture and other
Federal agencies, State
agencies including the
Agricultural Experiment
Stations, and local
participants
Custom Soil Resource
Report for
San Diego County
Area, California
Restaurant Row, San Marcos, CA
Natural
Resources
Conservation
Service
June 23, 2022
Preface
Soil surveys contain information that affects land use planning in survey areas.

They highlight soil limitations that affect various land uses and provide information about the properties of the soils in the survey areas. Soil surveys are designed for many different users, including farmers, ranchers, foresters, agronomists, urban planners, community officials, engineers, developers, builders, and home buyers.

Also, conservationists, teachers, students, and specialists in recreation, waste disposal, and pollution control can use the surveys to help them understand, protect, or enhance the environment.

Various land use regulations of Federal, State, and local governments may impose special restrictions on land use or land treatment. Soil surveys identify soil properties that are used in making various land use or land treatment decisions.

The information is intended to help the land users identify and reduce the effects of soil limitations on various land uses. The landowner or user is responsible for identifying and complying with existing laws and regulations.

Although soil survey information can be used for general farm, local, and wider area planning, onsite investigation is needed to supplement this information in some cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/ portal/nrcs/main/soils/health/) and certain conservation and engineering applications. For more detailed information, contact your local USDA Service Center (https://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil Scientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/? cid=nrcs142p2_053951).

Great differences in soil properties can occur within short distances. Some soils are seasonally wet or subject to flooding. Some are too unstable to be used as a foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic tank absorption fields. A high water table makes a soil poorly suited to basements or underground installations.

The National Cooperative Soil Survey is a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local agencies. The Natural Resources Conservation Service (NRCS) has leadership for the Federal part of the National Cooperative Soil Survey.

Information about soils is updated periodically. Updated information is available through the NRCS Web Soil Survey, the site for official soil survey information.

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require 2 alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer.
3 Contents
Preface.................................................................................................................... 2 How Soil Surveys Are Made..................................................................................5 Soil Map.................................................................................................................. 8 Soil Map................................................................................................................9 Legend................................................................................................................10 Map Unit Legend................................................................................................ 11 Map Unit Descriptions.........................................................................................11 San Diego County Area, California.................................................................13 PeA—Placentia sandy loam, 0 to 2 percent slopes, warm MAAT, MLRA 19...............................................................................................13 PeC—Placentia sandy loam, 2 to 9 percent slopes, warm MAAT, MLRA 19...............................................................................................14 PfA—Placentia sandy loam, thick surface, 0 to 2 percent slo pes.............. 15 RaB—Ramona sandy loam, 2 to 5 percent slopes..................................... 17 References............................................................................................................19 4 How Soil Surveys Are Made
Soil surveys are made to provide information about the soils and miscellaneous areas in a specific area. They include a description of the soils and miscellaneous areas and their location on the landscape and tables that show soil properties and limitations affecting various uses. Soil scientists observed the steepness, length, and shape of the slopes; the general pattern of drainage; the kinds of crops and native plants; and the kinds of bedrock. They observed and described many soil profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The profile extends from the surface down into the unconsolidated material in which the soil formed or from the surface down to bedrock. The unconsolidated material is devoid of roots and other living organisms and has not been changed by other biological activity.

Currently, soils are mapped according to the boundaries of major land resource areas (MLRAs). MLRAs are geographically associated land resource units that share common characteristics related to physiography, geology, climate, water resources, soils, biological resources, and land uses (USDA, 2006). Soil survey areas typically consist of parts of one or more MLRA.

The soils and miscellaneous areas in a survey area occur in an orderly pattern that is related to the geology, landforms, relief, climate, and natural vegetation of the area. Each kind of soil and miscellaneous area is associated with a particular kind of landform or with a segment of the landform. By observing the soils and miscellaneous areas in the survey area and relating their position to specific segments of the landform, a soil scientist develops a concept, or model, of how they were formed. Thus, during mapping, this model enables the soil scientist to predict with a considerable degree of accuracy the kind of soil or miscellaneous area at a specific location on the landscape.

Commonly, individual soils on the landscape merge into one another as their characteristics gradually change. To construct an accurate soil map, however, soil scientists must determine the boundaries between the soils. They can observe only a limited number of soil profiles. Nevertheless, these observations, supplemented by an understanding of the soil-vegetation-landscape relationship, are sufficient to verify predictions of the kinds of soil in an area and to determine the boundaries.

Soil scientists recorded the characteristics of the soil profiles that they studied. They noted soil color, texture, size and shape of soil aggregates, kind and amount of rock fragments, distribution of plant roots, reaction, and other features that enable them to identify soils. After describing the soils in the survey area and determining their properties, the soil scientists assigned the soils to taxonomic classes (units).

Taxonomic classes are concepts. Each taxonomic class has a set of soil characteristics with precisely defined limits. The classes are used as a basis for comparison to classify soils systematically. Soil taxonomy, the system of taxonomic classification used in the United States, is based mainly on the kind and character of soil properties and the arrangement of horizons within the profile. After the soil 5 scientists classified and named the soils in the survey area, they compared the individual soils with similar soils in the same taxonomic class in other areas so that they could confirm data and assemble additional data based on experience and research.

The objective of soil mapping is not to delineate pure map unit components; the objective is to separate the landscape into landforms or landform segments that have similar use and management requirements. Each map unit is defined by a unique combination of soil components and/or miscellaneous areas in predictable proportions. Some components may be highly contrasting to the other components of the map unit. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The delineation of such landforms and landform segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, onsite investigation is needed to define and locate the soils and miscellaneous areas.

Soil scientists make many field observations in the process of producing a soil map.

The frequency of observation is dependent upon several factors, including scale of mapping, intensity of mapping, design of map units, complexity of the landscape, and experience of the soil scientist. Observations are made to test and refine the soil-landscape model and predictions and to verify the classification of the soils at specific locations. Once the soil-landscape model is refined, a significantly smaller number of measurements of individual soil properties are made and recorded.

These measurements may include field measurements, such as those for color, depth to bedrock, and texture, and laboratory measurements, such as those for content of sand, silt, clay, salt, and other components. Properties of each soil typically vary from one point to another across the landscape.

Observations for map unit components are aggregated to develop ranges of characteristics for the components. The aggregated values are presented. Direct measurements do not exist for every property presented for every map unit component. Values for some properties are estimated from combinations of other properties.

While a soil survey is in progress, samples of some of the soils in the area generally are collected for laboratory analyses and for engineering tests. Soil scientists interpret the data from these analyses and tests as well as the field-observed characteristics and the soil properties to determine the expected behavior of the soils under different uses. Interpretations for all of the soils are field tested through observation of the soils in different uses and under different levels of management.

Some interpretations are modified to fit local conditions, and some new interpretations are developed to meet local needs. Data are assembled from other sources, such as research information, production records, and field experience of specialists. For example, data on crop yields under defined levels of management are assembled from farm records and from field or plot experiments on the same kinds of soil.

Predictions about soil behavior are based not only on soil properties but also on such variables as climate and biological activity. Soil conditions are predictable over long periods of time, but they are not predictable from year to year. For example, soil scientists can predict with a fairly high degree of accuracy that a given soil will have a high water table within certain depths in most years, but they cannot predict that a high water table will always be at a specific level in the soil on a specific date.

After soil scientists located and identified the significant natural bodies of soil in the survey area, they drew the boundaries of these bodies on aerial photographs and Custom Soil Resource Report
6 identified each as a specific map unit. Aerial photographs show trees, buildings, fields, roads, and rivers, all of which help in locating boundaries accurately.

Custom Soil Resource Report
7 Soil Map
The soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit. 8 9
Custom Soil Resource Report
Soil Map
3666120 3666170 3666220 3666270 3666320 3666370 3666420 3666470 3666520 3666120 3666170 3666220 3666270 3666320 3666370 3666420 3666470 3666520 482090 482140 482190 482240 482290 482340 482390
482090 482140 482190 482240 482290 482340 482390
33° 8' 14'' N
117° 11' 31'' W
33° 8' 14'' N
117° 11' 19'' W
33° 8' 0'' N
117° 11' 31'' W
33° 8' 0'' N
117° 11' 19'' W
N
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 11N WGS84 0 50 100 200 300
Feet
0 25 50 100 150
Meters
Map Scale: 1:2,000 if printed on A portrait (8.5" x 11") sheet.

Soil Map may not be valid at this scale.

MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Map Unit Polygons
Soil Map Unit Lines
Soil Map Unit Points
Special Point Features
Blowout
Borrow Pit
Clay Spot
Closed Depression
Gravel Pit
Gravelly Spot
Landfill
Lava Flow
Marsh or swamp
Mine or Quarry
Miscellaneous Water
Perennial Water
Rock Outcrop
Saline Spot
Sandy Spot
Severely Eroded Spot
Sinkhole
Slide or Slip
Sodic Spot
Spoil Area
Stony Spot
Very Stony Spot
Wet Spot
Other
Special Line Features
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at
1:24,000.

Warning: Soil Map may not be valid at this scale.

Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale.

Please rely on the bar scale on each map sheet for map
measurements.

Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:

Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required.

This product is generated from the USDA-NRCS certified data as of the version date(s) listed below.

Soil Survey Area: San Diego County Area, California
Survey Area Data: Version 16, Sep 13, 2021
Soil map units are labeled (as space allows) for map scales 1:50,000 or larger.

Date(s) aerial images were photographed: Jan 23, 2020—Feb 13, 2020
The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident.

Custom Soil Resource Report
10 Map Unit Legend
Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI PeA Placentia sandy loam, 0 to 2
percent slopes, warm MAAT,
MLRA 19

0.3 2.9%
PeC Placentia sandy loam, 2 to 9
percent slopes, warm MAAT,
MLRA 19

6.7 61.5%
PfA Placentia sandy loam, thick
surface, 0 to 2 percent slo
pes

3.8 34.6%
RaB Ramona sandy loam, 2 to 5
percent slopes

0.1 1.0%
Totals for Area of Interest 10.9 100.0%
Map Unit Descriptions
The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit.

A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class.

Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils.

Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it Custom Soil Resource Report
11 was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape.

The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas.

An identifying symbol precedes the map unit name in the map unit descriptions.

Each description includes general facts about the unit and gives important soil properties and qualities.

Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement.

Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series.

Some map units are made up of two or more major soils or miscellaneous areas.

These map units are complexes, associations, or undifferentiated groups.

A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps.

The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example.

An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha-Beta association, 0 to 2 percent slopes, is an example.

An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example.

Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example.

Custom Soil Resource Report
12 San Diego County Area, California
PeA—Placentia sandy loam, 0 to 2 percent slopes, warm MAAT, MLRA 19 Map Unit Setting
National map unit symbol: 2tyyl
Elevation: 200 to 2,520 feet
Mean annual precipitation: 17 to 19 inches
Mean annual air temperature: 63 to 64 degrees F
Frost-free period: 270 to 360 days
Farmland classification: Farmland of statewide importance Map Unit Composition
Placentia and similar soils: 85 percent
Minor components: 15 percent
Estimates are based on observations, descriptions, and transects of the mapunit.

Description of Placentia
Setting
Landform: Alluvial fans
Landform position (two-dimensional): Toeslope
Landform position (three-dimensional): Tread
Down-slope shape: Linear
Across-slope shape: Convex
Parent material: Alluvium derived from granitoid
Typical profile
H1 - 0 to 13 inches: sandy loam
H2 - 13 to 34 inches: sandy clay
H3 - 34 to 53 inches: sandy clay loam
H4 - 53 to 63 inches: sandy clay loam
Properties and qualities
Slope: 0 to 2 percent
Depth to restrictive feature: More than 80 inches
Drainage class: Well drained
Runoff class: Low
Capacity of the most limiting layer to transmit water (Ksat): Moderately low to moderately high (0.06 to 0.60 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Maximum salinity: Very slightly saline to moderately saline (2.0 to 8.0 mmhos/cm) Sodium adsorption ratio, maximum: 25.0
Available water supply, 0 to 60 inches: High (about 9.3 inches) Interpretive groups
Land capability classification (irrigated): 4s
Land capability classification (nonirrigated): 4s
Hydrologic Soil Group: C
Ecological site: R019XD061CA - CLAYPAN (1975)
Hydric soil rating: No
Custom Soil Resource Report
13 Minor Components
Placentia, thick surface
Percent of map unit: 7 percent
Hydric soil rating: No
Ramona
Percent of map unit: 7 percent
Hydric soil rating: No
Typic natrixeralfs, occasionally ponded
Percent of map unit: 1 percent
Landform: Depressions
Hydric soil rating: Yes
PeC—Placentia sandy loam, 2 to 9 percent slopes, warm MAAT, MLRA 19 Map Unit Setting
National map unit symbol: 2tyyn
Elevation: 150 to 2,950 feet
Mean annual precipitation: 13 to 18 inches
Mean annual air temperature: 62 to 64 degrees F
Frost-free period: 270 to 360 days
Farmland classification: Farmland of statewide importance Map Unit Composition
Placentia and similar soils: 85 percent
Minor components: 15 percent
Estimates are based on observations, descriptions, and transects of the mapunit.

Description of Placentia
Setting
Landform: Terraces, alluvial fans
Landform position (two-dimensional): Toeslope
Landform position (three-dimensional): Tread
Down-slope shape: Linear
Across-slope shape: Linear, convex
Parent material: Alluvium derived from granitoid
Typical profile
A1 - 0 to 4 inches: sandy loam
A2 - 4 to 13 inches: sandy loam
Bt1 - 13 to 21 inches: sandy clay
Bt2 - 21 to 34 inches: sandy clay
BC - 34 to 53 inches: sandy clay loam
C - 53 to 63 inches: sandy clay loam
Properties and qualities
Slope: 2 to 9 percent
Custom Soil Resource Report
14 Depth to restrictive feature: More than 80 inches
Drainage class: Well drained
Runoff class: Low
Capacity of the most limiting layer to transmit water (Ksat): Moderately low to moderately high (0.06 to 0.60 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Maximum salinity: Very slightly saline to moderately saline (2.0 to 8.0 mmhos/cm) Sodium adsorption ratio, maximum: 25.0
Available water supply, 0 to 60 inches: High (about 9.2 inches) Interpretive groups
Land capability classification (irrigated): 4e
Land capability classification (nonirrigated): 4e
Hydrologic Soil Group: C
Ecological site: R019XD061CA - CLAYPAN (1975)
Hydric soil rating: No
Minor Components
Fallbrook
Percent of map unit: 5 percent
Hydric soil rating: No
Bonsall
Percent of map unit: 5 percent
Hydric soil rating: No
Ramona
Percent of map unit: 4 percent
Hydric soil rating: No
Typic natrixeralfs, occasionally ponded
Percent of map unit: 1 percent
Landform: Depressions
Hydric soil rating: Yes
PfA—Placentia sandy loam, thick surface, 0 to 2 percent slo pes Map Unit Setting
National map unit symbol: hbfm
Elevation: 50 to 2,500 feet
Mean annual precipitation: 12 to 18 inches
Mean annual air temperature: 63 to 64 degrees F
Frost-free period: 200 to 300 days
Farmland classification: Farmland of statewide importance Map Unit Composition
Placentia and similar soils: 85 percent
Minor components: 11 percent
Custom Soil Resource Report
15 Estimates are based on observations, descriptions, and transects of the mapunit.

Description of Placentia
Setting
Landform: Alluvial fans
Landform position (two-dimensional): Toeslope
Landform position (three-dimensional): Base slope, rise Down-slope shape: Linear
Across-slope shape: Convex
Parent material: Alluvium derived from granite
Typical profile
H1 - 0 to 13 inches: sandy loam
H2 - 13 to 34 inches: clay
H3 - 34 to 63 inches: clay loam
Properties and qualities
Slope: 0 to 2 percent
Depth to restrictive feature: More than 80 inches
Drainage class: Moderately well drained
Runoff class: Very high
Capacity of the most limiting layer to transmit water (Ksat): Very low to moderately low (0.00 to 0.06 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Maximum salinity: Very slightly saline to moderately saline (2.0 to 8.0 mmhos/cm) Sodium adsorption ratio, maximum: 25.0
Available water supply, 0 to 60 inches: Low (about 5.1 inches) Interpretive groups
Land capability classification (irrigated): 3s
Land capability classification (nonirrigated): 4s
Hydrologic Soil Group: D
Ecological site: R019XD061CA - CLAYPAN (1975)
Hydric soil rating: No
Minor Components
Ramona
Percent of map unit: 5 percent
Hydric soil rating: No
Bonsall
Percent of map unit: 5 percent
Hydric soil rating: No
Unnamed, ponded
Percent of map unit: 1 percent
Landform: Depressions
Hydric soil rating: Yes
Custom Soil Resource Report
16 RaB—Ramona sandy loam, 2 to 5 percent slopes
Map Unit Setting
National map unit symbol: hbfr
Elevation: 250 to 3,500 feet
Mean annual precipitation: 10 to 20 inches
Mean annual air temperature: 63 degrees F
Frost-free period: 230 to 320 days
Farmland classification: Prime farmland if irrigated
Map Unit Composition
Ramona and similar soils: 85 percent
Minor components: 15 percent
Estimates are based on observations, descriptions, and transects of the mapunit.

Description of Ramona
Setting
Landform: Alluvial fans
Landform position (two-dimensional): Toeslope
Landform position (three-dimensional): Base slope, rise Down-slope shape: Linear
Across-slope shape: Convex
Parent material: Alluvium derived from granite
Typical profile
H1 - 0 to 17 inches: sandy loam
H2 - 17 to 60 inches: sandy clay loam
H3 - 60 to 74 inches: fine sandy loam
Properties and qualities
Slope: 2 to 5 percent
Depth to restrictive feature: More than 80 inches
Drainage class: Well drained
Runoff class: Medium
Capacity of the most limiting layer to transmit water (Ksat): Moderately high (0.20 to 0.57 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Available water supply, 0 to 60 inches: Moderate (about 8.5 inches) Interpretive groups
Land capability classification (irrigated): 2e
Land capability classification (nonirrigated): 4e
Hydrologic Soil Group: C
Ecological site: R019XG911CA - Loamy Fan
Hydric soil rating: No
Custom Soil Resource Report
17 Minor Components
Greenfield
Percent of map unit: 10 percent
Hydric soil rating: No
Plecentia
Percent of map unit: 5 percent
Hydric soil rating: No
Custom Soil Resource Report
18 References
American Association of State Highway and Transportation Officials (AASHTO). 2004. Standard specifications for transportation materials and methods of sampling and testing. 24th edition.

American Society for Testing and Materials (ASTM). 2005. Standard classification of soils for engineering purposes. ASTM Standard D2487-00.

Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of wetlands and deep-water habitats of the United States. U.S. Fish and Wildlife Service FWS/OBS-79/31.

Federal Register. July 13, 1994. Changes in hydric soils of the United States.

Federal Register. September 18, 2002. Hydric soils of the United States.

Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric soils in the United States.

National Research Council. 1995. Wetlands: Characteristics and boundaries.

Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service.

U.S. Department of Agriculture Handbook 18. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/national/soils/?cid=nrcs142p2_054262
Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for making and interpreting soil surveys. 2nd edition. Natural Resources Conservation Service, U.S. Department of Agriculture Handbook 436. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053577 Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of Agriculture, Natural Resources Conservation Service. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580 Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and Delaware Department of Natural Resources and Environmental Control, Wetlands Section.

United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of Engineers wetlands delineation manual. Waterways Experiment Station Technical Report Y-87-1.

United States Department of Agriculture, Natural Resources Conservation Service.

National forestry manual. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/ home/?cid=nrcs142p2_053374
United States Department of Agriculture, Natural Resources Conservation Service.

National range and pasture handbook. http://www.nrcs.usda.gov/wps/portal/nrcs/ detail/national/landuse/rangepasture/?cid=stelprdb1043084 19 United States Department of Agriculture, Natural Resources Conservation Service.

National soil survey handbook, title 430-VI. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/soils/scientists/?cid=nrcs142p2_054242
United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/? cid=nrcs142p2_053624
United States Department of Agriculture, Soil Conservation Service. 1961. Land capability classification. U.S. Department of Agriculture Handbook 210. http:// www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf Custom Soil Resource Report
20 APPENDIX D

APPENDIX D

RECOMMENDED GRADING SPECIFICATIONS
FOR

SAN MARCOS RESTAURANT ROW

SAN MARCOS, CALIFORNIA
PROJECT NO. G2487-32-03
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RECOMMENDED GRADING SPECIFICATIONS

1. GENERAL

1.1 These Recommended G rading Specifications shall be used in conjunction with the Geotechnical Report for the project prepared by Geocon. The recommendations contained in the text of the Geotechnical Report are a part of the earthwork and grading specifications and shall supersede the provisions contained hereinafter in the case of conflict.

1.2 Prior to the commencement of grading, a geotechnical consultant (Consultant) shall be employed for the purpose of observing earthwork procedures and testing the fills for substantial conformance with the recommendations of the Geotechnical Report and these specifications. The Consultant should provide adequate testing and observation services so that they may assess whether, in their opinion, the work was performed in substa ntial conformance with these specifications. It shall be the responsibility of the Contractor to assist the Consultant and keep them apprised of work schedules and changes so that personnel may be scheduled accordingly.

1.3 It shall be the so le responsibility of the Contractor to provide adequate equipment and methods to accomplish the work in accordance with applicable grading codes or agency ordinances, these specifications and the approved grading plans. If, in the opinion of the Consultant, unsatisfactory conditions such as questionable soil materials, poor moisture condition, inadequate compaction, and/or adverse weather result in a quality of work not in conformance with these specifications, the Consultant will be empowered to reject the work and recommend to the Owner that grading be stopped until the unacceptable conditions are corrected.

2. DEFINITIONS

2.1 Owner shall refer to the owner of the property or the entity on whose behalf the grading work is being p erformed and who has contracted with the Contractor to have grading performed.

2.2 Contractor shall refer to the Contractor performing the site grading work.

2.3 Civil Engineer or Engineer of Work shall refer to the California l icensed Civil Engineer or consulting firm responsible for preparation of the grading plans, surveying and verifying as-graded topography.

2.4 Consultant shall refer to the soil engineering and engineering geology consulting firm retained to provide geotechnical services for the project.

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2.5 Soil Engineer shall refer to a California licensed Civil Engineer retained by the Owner, who is experienced in the practice of geotechnical engineering. The Soil Engineer shall be responsible for having qualified representatives on-site to observe and test the Contractor's work for conformance with these specifications.

2.6 Engineering Geologist shall refer to a California licensed Engineering Geologist retained by the Owner to p rovide geologic observations and recommendations during the site grading.

2.7 Geotechnical Report shall refer to a soil report (including all addenda) which may include a geologic reconnaissance or geologic investigation that was prepared spe cifically for the development of the project for which these Recommended Grading Specifications are intended to apply.

3. MATERIALS

3.1 Materials for compacted fill shall consist of any soil excavated from the cut areas or imported to the site that, in the opinion of the Consultant, is suitable for use in construction of fills. In general, fill materials can be classified as soil fills, soil-rock fills or rock fills, as defined below.

3.1.1 Soil fills are defined as fills containi ng no rocks or hard lumps greater than 12 inches in maximum dimension and containing at least 40 percent by weight of material smaller than ¾ inch in size.

3.1.2 Soil-rock fills are defined as fills containing no rocks or hard lumps larger than 4 feet in maximum dimension and containing a sufficient matrix of soil fill to allow for proper compaction of soil fill around the rock fragments or hard lumps as specified in Paragraph 6.2. Oversize rock is defined as material greater than 12 inches.

3.1.3 Rock fills are defined as fills containing no rocks or hard lumps larger than 3 feet in maximum dimension and containing little or no fines. Fines are defined as material smaller than ¾ inch in maximum dimension. The quantity of fines shall be less than approximately 20 percent of the rock fill quantity.

3.2 Material of a perishable, spongy, or otherwise unsuitable nature as determined by the Consultant shall not be used in fills.

3.3 Materials used for fill, either imported or on -site, shall not contain hazardous materials as defined by the California Code of Regulations, Title 22, Division 4, Chapter 30, Articles 9 GI rev. 07/2015
and 10; 40CFR; and any other applicable local, state or federal laws. The Consultant shall not be responsible for the identi fication or analysis of the potential presence of hazardous materials. However, if observations, odors or soil discoloration cause Consultant to suspect the presence of hazardous materials, the Consultant may request from the Owner the termination of gradi ng operations within the affected area. Prior to resuming grading operations, the Owner shall provide a written report to the Consultant indicating that the suspected materials are not hazardous as defined by applicable laws and regulations.

3.4 The outer 15 feet of soil-rock fill slopes, measured horizontally, should be composed of properly compacted soil fill materials approved by the Consultant. Rock fill may extend to the slope face, provided that the slope is not steeper than 2:1 (horizontal:vertical) and a soil layer no thicker than 12 inches is track-walked onto the face for landscaping purposes. This procedure may be utilized provided it is acceptable to the governing agency, Owner and Consultant.

3.5 Samples of soil mater ials to be used for fill should be tested in the laboratory by the Consultant to determine the maximum density, optimum moisture content, and, where appropriate, shear strength, expansion, and gradation characteristics of the soil.

3.6 During grading, soil or groundwater conditions other than those identified in the Geotechnical Report may be encountered by the Contractor. The Consultant shall be notified immediately to evaluate the significance of the unanticipated condition.

4. CLEARING AND PREPARING AREAS TO BE FILLED

4.1 Areas to be excavated and filled shall be cleared and grubbed. Clearing shall consist of complete removal above the ground surface of trees, stumps, brush, vegetation, man -made structures, and sim ilar debris. Grubbing shall consist of removal of stumps, roots, buried logs and other unsuitable material and shall be per formed in areas to be graded. Roots and other projections exceeding 1½ inches in diameter shall be removed to a depth of 3 feet below the surface of the ground. Borrow areas shall be grubbed to the extent necessary to provide suitable fill materials.

4.2 Asphalt pavement material removed during clearing operations should be properly disposed at an approved off-site facility or in an acceptable area of the project evaluated by Geocon and the property owner . Concrete fragments that are free of reinforcing steel may be placed in fills, provided they are placed in accordance with Section 6.2 or 6.3 of this document.

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4.3 After clearing and grubbing of organic matter and other unsuitable material, loose or porous soils shall be removed to the depth recom mended in the Geotechnical Report. The depth of removal and compaction should be observed and approved by a repr esentative of the Consultant. The exposed surface shall then be plowed or scarified to a minimum depth of 6 inches and until the surface is free from uneven features that would tend to prevent uniform compaction by the equipment to be used.

4.4 Where the slope ratio of the original ground is steeper than 5:1 (horizontal:vertical), or where recommended by the Consultant, the original ground should be benched in accordance with the following illustration.

TYPICAL BENCHING DETAIL

Remove All
Unsuitable Material
As Recommended By
Consultant
Finish Grade Original Ground
Finish Slope Surface
Slope To Be Such That
Sloughing Or Sliding
Does Not Occur Varies
“B”
See Note 1
No Scale
See Note 2
1 2

DETAIL NOTES: (1) Key width "B" should be a minimum of 10 feet, or sufficiently wide to permit complete coverage with the compaction equipment used. The base of the key should be graded horizontal, or inclined slightly into the natural slope. (2) The outside of the key should be below the topsoil or unsuitable surficial material and at least 2 feet into dense forma tional material. Where hard rock is exposed in the bottom of the key, the depth and configuration of the key may be modified as approved by the Consultant.

4.5 After areas to receive fill have been cleared and scarified, the surface should be moisture conditioned to achieve the proper moisture content, and compacted as recommended in Section 6 of these specifications.

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5. COMPACTION EQUIPMENT

5.1 Compaction of soil or soil-rock fill shall be accomplished by sheepsfoot or segmented-steel wheeled rollers, vibratory rollers, multiple -wheel pneumatic-tired rollers, or other types of acceptable com paction equipment. Equipment shall be of such a design that it will be capable of compacting the soil or soil-rock fill to the specified relative compaction at the specified moisture content.

5.2 Compaction of rock fills shall be performed in accordance with Section 6.3.

6. PLACING, SPREADING AND COMPACTION OF FILL MATERIAL

6.1 Soil fill, as defined in Paragraph 3.1.1, shall be placed by the Contractor in accordance with the following recommendations:

6.1.1 Soil fill shall be placed by the Contractor in layers that, when compacted, should generally not exceed 8 inches. Each layer shall be spread evenly and shall be thoroughly mixed during spreading to obtain uniformity of material and moisture in each layer. The entire fill shall be constructed as a unit in nearly level lifts. Rock materials greater than 12 inches in maximum dimension shall be placed in accordance with Section 6.2 or 6.3 of these specifications.

6.1.2 In general, the soil fill shall be compacted at a m oisture content at or above the optimum moisture content as determined by ASTM D 1557.

6.1.3 When the moisture content of soil fill is below that specified by the Consultant, water shall be added by the Contractor until the moisture content is in the rang e specified.

6.1.4 When the moisture content of the soil fill is above the range specified by the Consultant or too wet to achieve proper compaction, the soil fill shall be aerated by the Contractor by blading/mixing, or other satisfactory methods until th e moisture content is within the range specified.

6.1.5 After each layer has been placed, mixed, and spread evenly, it shall be thoroughly compacted by the Contractor to a relative compaction of at least 90 percent.

Relative compaction is defined as the ra tio (expressed in percent) of the in -place dry density of the compacted fill to the maximum laboratory dry density as determined in accordance with ASTM D 1557. Compaction shall be continuous over the entire area, and compaction equipment shall make sufficient passes so that the specified minimum relative compaction has been achieved throughout the entire fill.

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6.1.6 Where practical, soils having an Expansion Index greater than 50 should be placed at least 3 feet below finish pad grade and should be compact ed at a moisture content generally 2 to 4 percent greater than the optimum moisture content for the material.

6.1.7 Properly compacted soil fill shall extend to the design surface of fill slopes. To achieve proper compaction, it is recommended that fill sl opes be over -built by at least 3 feet and then cut to the design grade. This procedure is considered preferable to track-walking of slopes, as described in the following paragraph.

6.1.8 As an alternative to over -building of slopes, slope faces may be back -rolled with a heavy-duty loaded sheepsfoot or vibratory roller at maximum 4 -foot fill height intervals. Upon completion, slopes should then be track -walked with a D -8 dozer or similar equipment, such that a dozer track covers all slope surfaces at least twice.

6.2 Soil-rock fill, as defined in Paragraph 3.1.2, shall be placed by the Contractor in accordance with the following recommendations:

6.2.1 Rocks larger than 12 inches but less than 4 feet in maximum dimension may be incorporated into the compacted soil fill, but shall be limited to the area measured 15 feet minimum horizontally from the slope face and 5 feet below finish grade or 3 feet below the deepest utility, whichever is deeper.

6.2.2 Rocks or rock fragments up to 4 feet in maximu m dimension may either be individually placed or placed in windrows. Under certain conditions, rocks or rock fragments up to 10 feet in maximum dimension may be placed using similar methods. The acceptability of placing rock materials greater than 4 feet i n maximum dimension shall be evaluated during grading as specific cases arise and shall be approved by the Consultant prior to placement.

6.2.3 For individual placement, sufficient space shall be provided between rocks to allow for passage of compaction equipment.

6.2.4 For windrow placement, the rocks should be placed in trenches excavated in properly compacted soil fill. Trenches should be approximately 5 feet wide and 4 feet deep in maximum dimension. The voids around and beneath rocks should be filled with approved granular soil having a Sand Equivalent of 30 or greater and should be compacted by flooding. Windrows may also be placed utilizing an "open-face" method in lieu of the trench procedure, however, this method should first be approved by the Consultant.

GI rev. 07/2015

6.2.5 Windrows should generally be parallel to each other and may be placed either parallel to or perpendicular to the face of the slope depending on the site geometry.

The minimum horizontal spacing for windrows shall be 12 feet center -to-center with a 5 -foot stagger or offset from lower courses to next overlying course. The minimum vertical spacing between windrow courses shall be 2 feet from the top of a lower windrow to the bottom of the next higher windrow.

6.2.6 Rock placement, fill placement and flooding of approved granular soil in the windrows should be continuously observed by the Consultant.

6.3 Rock fills, as defined in Section 3.1.3, shall be placed by the Contractor in accordance with the following recommendations:

6.3.1 The base of the rock fill shall be placed on a sloping surface (minimum slope of 2 percent). The surface shall slope toward suitable subdrainage outlet facilities. The rock fills shall be provided with subdrains during construction so that a hydrostatic pressure buildup does not develop. The subdrains shall be permanently connected to controlled drainage facilities to control post-construction infiltration of water.

6.3.2 Rock fills shall be placed in lifts not exceeding 3 feet. Placement shall be by rock trucks traversing previously placed lifts and dumping at the edge of the currently placed lift. Spreading of the rock fill shall be by dozer to facilitate seating of the rock. The rock fill shall be watered heavily during placement. Watering shall consist of water trucks traversing in front of the current rock lift face and spraying water continuously during rock placement. Compaction equipment with compactive energy comparable to or greater than that of a 20 -ton steel vibratory roller or other compaction eq uipment providing suitable energy to achieve the required compaction or deflection as recommended in Paragraph 6.3.3 shall be utilized. The number of passes to be made should be determined as described in Paragraph 6.3.3. Once a rock fill lift has been cov ered with soil fill, no additional rock fill lifts will be permitted over the soil fill.

6.3.3 Plate bearing tests, in accordance with ASTM D 1196, may be performed in both the compacted soil fill and in the rock fill to aid in determining the required minimum number of passes of the compaction equipment. If performed, a minimum of three plate bearing tests should be performed in the properly compacted soil fill (minimum relative compaction of 90 percent). Plate bearing tests shall then be performed on area s of rock fill having two passes, four passes and six passes of the compaction equipment, respectively. The number of passes required for the rock fill shall be determined by comparing the results of the plate bearing tests for the soil fill and the rock fill and by evaluating the deflection GI rev. 07/2015
variation with number of passes. The required number of passes of the compaction equipment will be performed as necessary until the plate bearing deflections are equal to or less than that determined for the properly compacted soil fill. In no case will the required number of passes be less than two.

6.3.4 A representative of the Consultant should be present during rock fill operations to observe that the minimum number of “passes” have been obtained, that water is being properly applied and that specified procedures are being followed. The actual number of plate bearing tests will be determined by the Consultant during grading.

6.3.5 Test pits shall be excavated by the Contractor so that the Consultant can state that, in their opinion, sufficient water is present and that voids between large rocks are properly filled with smaller rock material. In -place density testing will not be required in the rock fills.

6.3.6 To reduce the potential for “piping” of fines into the rock fill from overlying soil fill material, a 2 -foot layer of graded filter material shall be placed above the uppermost lift of rock fill. The need to place graded filter material below the rock should be determined by the Consultant prior to commencing gr ading. The gradation of the graded filter material will be determined at the time the rock fill is being excavated. Materials typical of the rock fill should be submitted to the Consultant in a timely manner, to allow design of the graded filter prior to t he commencement of rock fill placement.

6.3.7 Rock fill placement should be continuously observed during placement by the Consultant.

7. SUBDRAINS

7.1 The geologic units on the site may have permeability characteristics and/or fr acture systems that could be susceptible under certain conditions to seepage. The use of canyon subdrains may be necessary to mitigate the potential for adverse impacts associated with seepage conditions. Canyon subdrains with lengths in excess of 500 feet or extensions of existing offsite subdrains should use 8-inch-diameter pipes. Canyon subdrains less than 500 feet in length should use 6-inch-diameter pipes.

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TYPICAL CANYON DRAIN DETAIL

7.2 Slope drains within stability fill keyways should use 4-inch-diameter (or lager) pipes.

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TYPICAL STABILITY FILL DETAIL

7.3 The actual subdrain locations will be evaluated in the field during the remedial grading operations. Additional drains may be necessary depending on the conditio ns observed and the requirements of the local regulatory agencies. Appropriate subdrain outlets should be evaluated prior to finalizing 40-scale grading plans.

7.4 Rock fill or soil-rock fill areas may require subdrains along their down-slope perimeters to mitigate the potential for buildup of water from construction or landscape irrigation. The subdrains should be at least 6-inch-diameter pipes encapsulated in gravel and filter fabric .

Rock fill drains should be constructed using the same requirements as canyon subdrains.

GI rev. 07/2015

7.5 Prior to outletting, the final 20 -foot segment of a subdrain that will not be extended during future development should consist of non -perforated drainpipe. At the non -perforated/ perforated interface, a see page cutoff wall should be constructed on the downslope side of the pipe.

TYPICAL CUT OFF WALL DETAIL

7.6 Subdrains that discharge into a natural drainage course or open space area should be provided with a permanent headwall structure.

GI rev. 07/2015

TYPICAL HEADWALL DETAIL

7.7 The final grading plans should show the location of the proposed subdrains. After completion of remedial excavations and subdrain installation, the project civil engineer should survey the drain locations and prep are an “as -built” map showing the drain locations. The final outlet and connection locations should be determined during grading operations. Subdrains that will be extended on adjacent projects after grading can be placed on formational material and a vertical riser should be placed at the end of the subdrain. The grading contractor should consider videoing the subdrains shortly after burial to check proper installation and functionality. The contractor is responsible for the performance of the drains.

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8. OBSERVATION AND TESTING

8.1 The Consultant shall be the Owner’s representative to observe and perform tests during clearing, grubbing, filling, and compaction operations. In general, no more than 2 feet in vertical elevation of soil or soil-rock fill should be placed without at least one field density test being performed within that interval. In addition, a minimum of one field density test should be performed for every 2,000 cubic yards of soil or soil-rock fill placed and compacted.

8.2 The Consultant should perform a sufficient distribution of field density tests of the compacted soil or soil-rock fill to provide a basis for expressing an opinion whether the fill material is compacted as specified. Density tests sh all be performed in the compacted materials below any disturbed surface. When these tests indicate that the density of any layer of fill or portion thereof is below that specified, the particular layer or areas represented by the test shall be reworked until the specified density has been achieved.

8.3 During placement of rock fill, the Consultant should observe that the minimum number of passes have been obtained per the criteria discussed in Section 6.3.3. The Consultant should request the e xcavation of observation pits and may perform plate bearing tests on the placed rock fills. The observation pits will be excavated to provide a basis for expressing an opinion as to whether the rock fill is properly seated and sufficient moisture has been applied to the material. When observations indicate that a layer of rock fill or any portion thereof is below that specified, the affected layer or area shall be reworked until the rock fill has been adequately seated and sufficient moisture applied.

8.4 A settlement monitoring program designed by the Consultant may be conducted in areas of rock fill placement. The specific design of the monitoring program shall be as recommended in the Conclusions and Recommendations section of the project Geotechnical Report or in the final report of testing and observation services performed during grading.

8.5 We should observe the placement of subdrains, to check that the drainage devices have been placed and constructed in substantial conformance with project specifications.

8.6 Testing procedures shall conform to the following Standards as appropriate:

8.6.1 Soil and Soil-Rock Fills:

8.6.1.1 Field Density Test, ASTM D 1556, Density of Soil In -Place By the Sand-Cone Method.

GI rev. 07/2015

8.6.1.2 Field Density Test, Nuclear Method, ASTM D 6938, Density of Soil and Soil-Aggregate In-Place by Nuclear Methods (Shallow Depth).

8.6.1.3 Laboratory Compaction Test, ASTM D 1557, Moisture-Density Relations of Soils and Soil -Aggregate Mixtures Using 10 -Pound Hammer and 18-Inch Drop.

8.6.1.4. Expansion Index Test, ASTM D 4829, Expansion Index Test.

9. PROTECTION OF WORK

9.1 During construction, the Contractor shall properly grade all excavated surfaces to provide positive drainag e and prevent ponding of water. Drainage of surface water shall be controlled to avoid damage to adjoining properties or to finished work on the site. The Contractor shall take remedial measures to prevent erosion of freshly graded areas until such time as permanent drainage and erosion control features have been installed. Areas subjected to erosion or sedimentation shall be properly prepared in accordance with the Specifications prior to placing additional fill or structures.

9.2 After compl etion of grading as observed and tested by the Consultant, no further excavation or filling shall be conducted except in conjunction with the services of the Consultant.

10. CERTIFICATIONS AND FINAL REPORTS

10.1 Upon completion of the work, Contractor shall furnish Owner a certification by the Civil Engineer stating that the lots and/or building pads are graded to within 0.1 foot vertically of elevations shown on the grading plan and that all tops and toes of slopes are within 0.5 foot horizontally of the positions shown on the grading plans. After installation of a section of subdrain, the project Civil Engineer should survey its location and prepare an as-built plan of the subdrain location. The project Civil Engineer should verify the proper outlet for the subdrains and the Contractor should ensure that the drain system is free of obstructions.

10.2 The Owner is responsible for furnishing a final as -graded soil and geologic report satisfactory to the appropriate govern ing or accepting agencies. The as -graded report should be prepared and signed by a California licensed Civil Engineer experienced in geotechnical engineering and by a California Certified Engineering Geologist, indicating that the geotechnical aspects of t he grading were performed in substantial conformance with the Specifications or approved changes to the Specifications.

Geocon Project No. G2487-32-03 December 22, 2022

LIST OF REFERENCES

1. 2019 California Building Code, California Code of Regulations, Title 24, Part 2, based on the 2018 International Building Code, prepared by California Building Standards Commission, dated July 2019.

2. ACI 330-08, Guide for the Design and Construction of Concrete Parking Lots, prepared by the American Concrete Institute, dated June 2008.

3. American Concrete Institute, ACI 318-11, Building Code Requirements for Structural Concrete and Commentary, dated August, 2011.

4. American Society of Civil Engineers (ASCE), ASCE 7-16, Minimum Design Loads and Associated Criteria for Buildings and Other Structures, 2017.

5. Anderson, J. G., T. K. Rockwell, and D. C. Agnew, Past and Possible Future Earthquakes of Significance to the San Diego Region: Earthquake Spectra, v. 5, no. 2, p. 299-333, 1989.

6. California Department of Conservation, Division of Mines and Geology, Probabilistic Seismic Hazard Assessment for the State of California, Open File Report 96-08, 1996.

7. California Geological Survey, Seismic Shaking Hazards in California, Based on the USGS/CGS Probabilistic Seismic Hazards Assessment (PSHA) Model, 2002 (revised April 2003). 10% probability of being exceeded in 50 years.
http://redirect.conservation.ca.gov/cgs/rghm/pshamap/pshamain.html

8. Geocon Incorporated, Update Geotechnical Investigation, Old California Restaurant Row, 1000-1080 West San Marcos Boulevard, Sand Marcos, California, dated February 6, 2020 (Project No. G2487-42-01).

9. http://www.water.ca.gov.

10. http://websoilsurvey.nrcs.usda.gov.

11. http://earthquake.usgs.gov/designmaps/us/application.php.

12. Kennedy, M. P. and S. S. Tan, Geologic Map of the Oceanside 30’x60’ Quadrangle, California, USGS Regional Map Series, Scale 1:100,000, 2005.

13. Unpublished reports and maps on file with Geocon Incorporated.

14. USGS computer program, Seismic Hazard Curves and Uniform Hazard Response Spectra.

San Marcos City CouncilDecember 12, 2023

San Marcos City Council
December 12, 2023