HomeMy WebLinkAboutCT 2023-0005; JUNIPER COAST HOMES; GEOTECHNICAL CHANGE OF CONSULTANT OF RECORD AND ADDENDUM GEOTECHNICAL RECOMMENDATIONS; 2025-12-04
9272 Jeronimo Road, Suite 104, Irvine CA 92618 (949) 297-3856
LGC Valley, Inc.
Geotechnical Consulting
December 4, 2025 (revised February 17, 2026) Project No. 254003-01
Ms Aylene Chu
Toll Brothers
350 Commerce, Suite 200
Irvine, California 92602
Subject: Geotechnical Change of Consultant of Record and Addendum Geotechnical
Recommendations, Juniper Coast Homes, Lot 2 in Block "Q" of Palisades No. 2,
270 Juniper Avenue, Carlsbad, California
Introduction
In accordance with the request, LGC Valley, Inc. (LGC) has prepared this letter to provide a geotechnical
change of consultant of record and addendum foundation design recommendation based on the latest adopted
building code (i.e. 2022 California Building Code) for the proposed single-family residential development
located at 270 Juniper Avenue, Carlsbad, California. The prior geotechnical reports by GeoTek, dated
October 26, 2023, April 4, 2025, and August 4, 2025 (GeoTek, 2023, 2025a, and 2025b) provided the
geotechnical recommendations for the project and are included in this report as Appendix B.
Geotechnical Change of Consultant of Record
LGC has reviewed information with respect to the subject site and accepts responsibility as geotechnical
engineer of record for the proposed residential development located at 270 Juniper Avenue, City of Carlsbad,
California. LGC has reviewed, accepts, and concurs with the information presented in the referenced Preliminary
Geotechnical Report, dated October 26, 2023, the Response to Third-Party Review Comments Report, dated
March 24, 2025, revised April 4, 2025; and the Updated Onsite Infiltration Recommendations Report, dated June
7, 2025, revised August 4, 2025 prepared by GeoTek, Inc. (GeoTek, 2023, 2025a, and 2025b) that are included
in Appendix B with respect to the subject site. Based on our review of the project documents, the findings,
conclusions and recommendations contained within the referenced geotechnical report remain applicable for the
subject site, unless modified herein.
Conclusions
Geotechnical recommendations present in the project geotechnical reports (GeoTek, 2023, 2025a, and 2025b)
remain applicable and should be followed during the design and construction of the project, unless modified
herein. Based on the results of our geotechnical review, it is our opinion that the proposed site development
is feasible from a geotechnical standpoint, provided the recommendations included in the refenced report and
those included herein are incorporated into the project plans and specifications, and followed during site
grading and construction.
Project No. 254003-01 Page 2 February 17, 2026
Addendum Geotechnical Recommendations
The following geotechnical recommendations should be incorporated into the design and construction of the
proposed single family residential structures for the project.
Based on our review of the project geotechnical report (GeoTek, Inc., 2023), the expansion potential testing of
the on-site soils indicated the finish grade soils on the building pads will likely be in the very low range;
however, very low to low expansive soils (EI 0-50) may be present on the site.
Remedial Grading
Based on our professional experience with sites in the general vicinity of downtown Carlsbad, we antipate the
remedial removals of the potentially compressible near surface soils will range from approximately 3 to 5 feet
in depth (and that shrinkage of these soils may be on the order of 10 to 15 percent shrinkage). However,
deeper removals may be required based on geotechnical observation and testing of the on-site Quaternary-aged
Old Paralic Deposits/Terrace Deposits during site grading. These deeper removals may include backfilling of
the root ball excavations of the on-site orchard tress and other existing trees. The soils can be reused as
compacted fill provided the soil is free of organics and other deleterious material and moisture-conditioned to
a near optimum moisture content prior to compaction.
In additional, our professional experience indicates that shallow sewage seepage pit(s) may be present on the
site due to the site usage since the 1930’s. If encountered, the pit(s) should be removed or backfilled with a 2-
sack sand cement slurry.
Post-Tension Foundation Design Recommendations
We have reviewed the prior project preliminary post-tension foundation recommendations letter dated June 20,
2025 (GeoTek, 2025). The previous recommendations remain applicable for very low expansive soils. However,
if low expansive soils (i.e. Expansion Index of 21-50) are encountered onsite at finish pad grade, the following
additional design parameters should be used.
Bearing Capacity
Shallow foundations may be designed for a maximum allowable bearing capacity of 2,000 lb/ft2
(gross), for continuous footings a minimum of 12 inches wide and 12 inches deep and spread footings
24 inches wide and 18 inches deep, into certified compacted fill. A factor of safety greater than 3 was
used in evaluating the above bearing capacity value. This value may be increased by 300 psf for each
additional foot in depth and 200 psf for each additional foot of width to a maximum value of 3,000 psf.
Bearing values indicated above are for total dead loads and frequently applied live loads. The above
vertical bearing may be increased by one-third for short durations of loading which will include the
effect of wind or seismic forces.
Lateral forces on footings may be resisted by passive earth resistance and friction at the bottom of the
footing. Foundations may be designed for a coefficient of friction of 0.35, and a passive earth pressure
of 200 lb/ft2/ft to a maximum value of 3,000 psf. The passive earth pressure incorporates a factor of
Project No. 254003-01 Page 3 February 17, 2026
safety of approximately 1.5. The above passive pressure may be increased by one-third for short
durations of loading which will include the effect of wind or seismic forces. Lateral passive resistance is
based on the assumption that backfill next to the foundations is properly compacted.
All footing excavations should be cut square and level as much as possible, and should be free of
sloughed materials including sand, rocks and gravel, and trash debris. Subgrade soils should be pre-
moistened for the very low to low expansion potential. These allowable bearing pressures are applicable
for level (ground slope equal to or flatter than 5H:1V) conditions only.
Post-Tension Foundations
Based on the site geotechnical conditions and provided the remedial recommendations provided herein
are implemented, the site may be considered suitable for the support of the anticipated structures using
a post-tensioned slab-on-grade foundation system for very low to low expansion potential (0-50
Expansion Index). The following section summaries our recommendations for the foundation system.
The post-tension parameters provided in the following table are based on the expansion potential only,
and do not incorporate any increase for static and seismically induced differential settlements. Finish
grade laboratory testing should be performed to confirm the finish grade expansion potential.
Project No. 254003-01 Page 4 February 17, 2026
Preliminary Geotechnical Parameters for Post-Tensioned Foundation Design
Parameter Value
Expansion Classification (Assumed to be confirmed at
the completion of grading):
Low Expansion
Thornthwaite Moisture Index (From Figure 3.3): -20
Constant Soil Suction (From Figure 3.4): PF 3.6
Center Lift:
Edge moisture variation distance (from Figure
3.6), em:
Center lift, ym:
Low
9.0 feet
0.30 inches
Edge Lift:
Edge moisture variation distance (from Figure
3.6), em:
Edge lift, ym:
Low
5.2 feet
0.61 inches
Soluble Sulfate Content for Design of Concrete Mix in
Contact with Site Soils in Accordance with American
Concrete Institute standard 318, Section 4.3:
Negligible Exposure
(Based on preliminary testing – needs to be
confirmed at the completion of grading)
Corrosivity of Earth Materials to Ferrous Metals: Moderately Corrosive
Modulus of Subgrade Reaction, k (assuming
presaturation as indicated below): 100 pci
Additional Recommendations:
1. Presaturate slab subgrade to at least 1.2 times optimum moisture, to minimum depths of 12 inches
below ground surface, respectively for low expansion potentials.
2. Install an underslab moisture/vapor barrier. The underslab moisture retarder (i.e. an equivalent
capillary break method) should consist of a 15-mil thick polyolefin (or equivalent) in conformance
with ASTM E 1745 Class A material underlain by a minimum 1-inch of sand, as needed. The sand
layer requirements above the vapor barrier are the purview of the foundation engineer/structural
engineer, and should be provided in accordance with ACI Publication 302 “Guide for Concrete Floor
and Slab Construction”. These recommendations must be confirmed (and/or altered) by the
foundation engineer, based upon the performance expectations of the foundation. Ultimately, the
design of the moisture retarder system and recommendations for concrete placement and curing are
the purview of the foundation engineer, in consideration of the project requirements provided by the
architect and developer.
3. Minimum perimeter foundation embedment below finish grade for moisture cut off should be 12
inches.
4. Minimum slab thickness should be 5 inches.
* The above sand and Visqueen recommendations are traditionally included with geotechnical foundation
recommendations although they are generally not a major factor influencing the geotechnical performance of the
foundation. The sand and Visqueen requirements are the purview of the foundation engineer/corrosion engineer
(in accordance with ACI Publication 302 “Guide for Concrete Floor and Slab Construction”) and the homebuilder
to ensure that the concrete cures more evenly than it would otherwise, is protected from corrosive environments,
and moisture penetration of through the floor is acceptable to future homeowners. Therefore, the above
recommendations may be superseded by the requirements of the previously mentioned parties.
Project No. 254003-01 Page 5 February 17, 2026
Foundation Settlement
Based on our current understanding of the project, the results of our site investigation and the
recommended remedial grading with shallow foundations embedded into compacted fills, we estimate
the post-construction static settlement of the site to be 1-inch with a differential settlement of
approximately 0.5-inches in 40 feet.
Corrosivity to Concrete and Metal
The National Association of Corrosion Engineers (NACE) defines corrosion as “a deterioration of a substance
or its properties because of a reaction with its environment.” From a geotechnical viewpoint, the
“environment” is the prevailing foundation soils and the “substances” are the reinforced concrete foundations
or various buried metallic elements such as rebar, piles, pipes, etc., which are in direct contact with or within
close vicinity of the foundation soil.
In general, soil environments that are detrimental to concrete have high concentrations of soluble sulfates
and/or pH values of less than 5.5. ACI 318R-14 Table 19.3.1.1, provides specific guidelines for the concrete
mix design when the soluble sulfate content of the soils exceeds 0.1 percent by weight or 1,000 ppm. The
minimum amount of chloride ions in the soil environment that are corrosive to steel, either in the form of
reinforcement protected by concrete cover, or plain steel substructures such as steel pipes or piles, is 500 ppm
per California Test 532.
Based on our understanding of the soils within the subject area, the onsite soils are considered as having a
negligible/S0 sulfate exposure condition in accordance with ACI 318R-14 Table 19.3.1.1. As a preliminary
recommendation due to results of sulfate content testing, concrete in contact with onsite soils should be
designed in accordance with ACI 318R-14 Table 19.3.1.1 for the negligible/S0 category. It is also our opinion
that onsite soils should be considered moderately corrosive to buried metals. The client and/or other members
of the design team should consider this potential as they determine necessary. LGC is not a corrosion
consultant and does not provide recommendations related to corrosion. Finish grade laboratory testing should
be performed to confirm the finish grade corrosion potential of the site soils.
Limitations
Our services were performed using the degree of care and skill ordinarily exercised, under similar
circumstances, by reputable engineers and geologists practicing in this or similar localities. No other
warranty, expressed or implied, is made as to the conclusions and professional advice included in this report.
The samples taken and submitted for laboratory testing, the observations made, and the in-situ field testing
performed are believed representative of the entire project; however, soil and geologic conditions revealed
by excavation may be different than our preliminary findings. If this occurs, the changed conditions must be
evaluated by the project soils engineer and geologist and design(s) adjusted as required or alternate design(s)
recommended.
This report is issued with the understanding that it is the responsibility of the owner, or of his/her
representative, to ensure that the information and recommendations contained herein are brought to the
attention of the architect and/or project engineer and incorporated into the plans, and the necessary steps are
taken to see that the contractor and/or subcontractor properly implements the recommendations in the field.
Project No. 254003-01 Page 6 February 17, 2026
The contractor and/or subcontractor should notify the owner if they consider any of the recommendations
presented herein to be unsafe.
The findings of this report are valid as of the present date. However, changes in the conditions of a property
can and do occur with the passage of time, whether they be 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.
Closure
If you have any questions regarding our letter, please contact this office. We appreciate this opportunity to be
of service.
Respectfully submitted,
LGC VALLEY, INC.
Randall K. Wagner, CEG 1612 Basil Hattar, GE 2734
Senior Project Geologist Principal Engineer
Attachments: Appendix A - References
Appendix B - Preliminary Geotechnical Report by GeoTek Inc., dated October 26, 2023;
Response to Third-Party Review Comments Report by GeoTek Inc., dated March 24, 2025,
revised April 4, 2025; and Updated Onsite Infiltration Recommendations Report by GeoTek
Inc., dated June 7, 2025, revised August 4, 2025
Distribution: (1) Addressee (via e-mail)
I.JJ1K~
Project No. 254003-01 Page A-1 February 17, 2026
Appendix A
References
American Concrete Institute (ACI), 2019, Building Code Requirements for Structural Concrete (ACI 318-19)
and Commentary, an ACI Standard, reported by ACI Committee 318.
American Society of Civil Engineers (ASCE), 2017, Minimum Design Loads for Buildings and Other
Structures, ASCE/SEI 7-16.
California Building Standards Commission, 2022 California Building Code, California Code of Regulations
Title 24, Volumes 1 and 2, dated July 2022.
Pasco, Laret, Suiter, and Associates, Inc. (PLSA Engineering), 2025a, Improvement Plans for Juniper Coast
Homes, 270 Juniper Avenue, Project No. CT 2023-0005, Drawing No. 551-3, 4 Sheets, dated October
17, 2025.
PLSA Engineering, 2025b, Grading Plans for Juniper Coast Homes, 270 Juniper Avenue, Project No. CT
2023-0005, Drawing No. 551-3A, 10 Sheets, dated December 5, 2025.
GeoTek, Inc., 2023, Preliminary Geotechnical, Proposed Residential Development, 270 Juniper Avenue
Carlsbad, California 92008, Project No. 3944-SD, dated October 26, 2023.
GeoTek, Inc., 2025a, Response to Third-Party Review Comments, Proposed Residential Development, 270
Juniper Avenue, Carlsbad, California 92008, Project No. 3944-SD, dated March 24, 2025, revised April 4,
2025.
GeoTek, Inc., 2025b, Updated Onsite Infiltration Recommendations, Proposed Residential Development, 270
Juniper Avenue, Carlsbad, California 92008, Project No. 3944-SD, dated June 7, 2025, revised August 4,
2025.
Gouvis Engineering Consulting Group Inc., 2025, Post-Tension Foundation Plans, Juniper Coast Homes, 270
Juniper Avenue, Carlsbad, CA, Project No. 66646, dated May 23, 2025.
Kirk Moeller Architects, Inc, 2025, Juniper Coat Homes Building Plans, 235 Sheets, File No. A0.1, dated
February 13, 2025, Delta 2 Revision dated May 23, 2025.
Post-Tensioning Institute, 2006, Design of Post Tensioned Slabs-on-Ground, Third Addition, Addendum 1 dated
May 2007, and Addendum 2 dated May 2008, with Errata February 4, 2010.
Project No. 254003-01 Page B-1 February 17, 2026
Appendix B
Preliminary Geotechnical Report by GeoTek Inc., dated October 26, 2023
Response to Third-Party Review Comments Report by GeoTek Inc., dated March 24,
2025, revised April 4, 2025
Updated Onsite Infiltration Recommendations Report by GeoTek Inc., dated June 7,
2025, revised August 4, 2025
PRELIMINARY GEOTECHNICAL
PROPOSED RESIDENTIAL DEVELOPMENT
270 JUNIPER AVENUE
CARLSBAD, CALIFORNIA, 92008
PREPARED FOR
RINCON HOMES
5315 AVENIDA ENCINAS, SUITE 200
CARLSBAD, CALIFORNIA 92008
PREPARED BY
GEOTEK, INC.
1384 POINSETTIA AVENUE, SUITE A
VISTA, CALIFORNIA 92081
PROJECT NO. 3944-SD OCTOBER 26, 2023
Project No. 254003-01 B - 1 February 17, 2026
GEOTEK
GEOTEK
GEOTECHNICAL | ENVIRONMENTAL | MATERIALS
October 26, 2023
Project No. 3944-SD
Rincon Homes
5315 Avenida Encinas, Suite 200
Carlsbad, California 92008
Attention: Mr. Tom St. Claire
Subject: Preliminary Geotechnical
Proposed Residential Development
270 Juniper Avenue
Carlsbad, California 92008
Dear Mr. St. Claire:
GeoTek, Inc. (GeoTek) is pleased to provide herein the results of this preliminary
geotechnical evaluation for the subject project. This report presents the results of
GeoTek’s evaluation and provides preliminary geotechnical recommendations for
earthwork, foundation design, infiltration rates and construction. Based upon review,
site development appears feasible from a geotechnical viewpoint provided that the
recommendations included herein are incorporated into the design and construction phases
of site development. The opportunity to be of service is sincerely appreciated. If you should
have any questions, please do not hesitate to contact GeoTek.
Respectfully submitted,
GeoTek, Inc.
Christopher D. Livesey
CEG 2733, Exp. 05/31/25
Vice President
Edward R. Cunningham
RCE 81687, Exp. 03/31/24
Project Engineer
Distribution: (1) Addressee
Project No. 254003-01 B - 2 February 17, 2026
GeoTek, Inc.
1384 Poinsettia Avenue, Suite A Vista, CA 92081-8505
(760) 599-0509 Office (760) 599-0S93 Fa www.geotekusa.com
RINCON HOMES Project No. 3944-SD
Preliminary Geotechnical October 26, 2023
270 Juniper Avenue, Carlsbad, California 92008 Page i
TABLE OF CONTENTS
1. PURPOSE AND SCOPE OF SERVICES .................................................................................................... 1
2. SITE DESCRIPTION AND PROPOSED DEVELOPMENT .................................................................... 1
2.1 Site Description ................................................................................................................................ 1
2.2 Proposed Development ..................................................................................................................... 1
3. FIELD EXPLORATION AND LABORATORY TESTING ...................................................................... 2
3.1 Field Exploration ............................................................................................................................... 2
3.2 Laboratory Testing ............................................................................................................................ 3
4. GEOLOGIC AND SOILS CONDITIONS ................................................................................................... 4
4.1 Regional Setting ................................................................................................................................ 4
4.2 EARTH MATERIALS ......................................................................................................................... 4
Artificial Fill (Not Mapped) ................................................................................................................ 4
Old Paralic Deposits (Map Symbol Qop) ............................................................................................ 4
4.3 SURFACE WATER AND GROUNDWATER ........................................................................................ 5
Surface Water .................................................................................................................................. 5
Groundwater .................................................................................................................................... 5
4.4 EARTHQUAKE HAZARDS ................................................................................................................ 5
Surface Fault Rupture ....................................................................................................................... 5
Liquefaction/Seismic Settlement......................................................................................................... 5
Other Seismic Hazards ..................................................................................................................... 6
5. CONCLUSIONS AND RECOMMENDATIONS ........................................................................................ 6
5.1 General ............................................................................................................................................ 6
5.2 EARTHWORK CONSIDERATIONS ................................................................................................... 6
General ............................................................................................................................................ 6
Site Clearing and Preparation ............................................................................................................ 7
Remedial Grading ............................................................................................................................. 7
Engineered Fill .................................................................................................................................. 7
Excavation Characteristics ................................................................................................................. 8
Trench Excavations and Backfill ........................................................................................................ 8
5.3 DESIGN RECOMMENDATIONS ....................................................................................................... 8
Foundation Design Criteria ................................................................................................................ 8
Under Slab Moisture Membrane ..................................................................................................... 10
Miscellaneous Foundation Recommendations ................................................................................... 11
Foundation Setbacks ....................................................................................................................... 11
Seismic Design Parameters ............................................................................................................. 12
Soil Sulfate Content ........................................................................................................................ 12
General Concrete Flatwork .............................................................................................................. 12
Retaining Wall Design and Construction .......................................................................................... 13
5.3.9 Wall Backfill and Drainage ............................................................................................................. 14
5.4 POST CONSTRUCTION CONSIDERATIONS ................................................................................... 15
Landscape Maintenance and Planting .............................................................................................. 15
Drainage ........................................................................................................................................ 15
5.5 PLAN REVIEW AND CONSTRUCTION OBSERVATIONS ................................................................. 15
6. LIMITATIONS ............................................................................................................................................. 16
7. SELECTED REFERENCES ....................................................................................................................... 18
Project No. 254003-01 B - 3 February 17, 2026
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GEOTEK
RINCON HOMES Project No. 3944-SD
Preliminary Geotechnical October 26, 2023
270 Juniper Avenue, Carlsbad, California 92008 Page ii
TABLE OF CONTENTS
ENCLOSURES
Figure 1 – Site Location Map
Figure 2 – Geotechnical Map
Appendix A – Logs of Exploration
Appendix B – Results of Laboratory Testing
Appendix C – Percolation Data Sheets & Porchet Calculations
– City of Carlsbad BMP Design Manual: Appendix D Forms
Appendix D – General Earthwork Grading Guidelines
Project No. 254003-01 B - 4 February 17, 2026
GEOTEK
RINCON HOMES Project No. 3944-SD
Preliminary Geotechnical October 26, 2023
Juniper Avenue, Carlsbad, California 92008 Page 1
1. PURPOSE AND SCOPE OF SERVICES
The purpose of this study was to evaluate the geotechnical conditions of the project site. Services
provided for this study included the following:
Research and review of available geologic and geotechnical data, and general information
pertinent to the site.
Excavation of two exploratory borings and collection of soil samples for subsequent
laboratory testing.
Excavation of two additional borings to a depth of about two feet below grade and
performing a percolation test in each boring,
Laboratory analysis of soil samples collected during the field investigation.
Compilation of this geotechnical report which presents GeoTek’s findings of pertinent
site geotechnical conditions and geotechnical recommendations for site development.
2. SITE DESCRIPTION AND PROPOSED DEVELOPMENT
2.1 Site Description
The subject project site is located at Assessor Parcel Number 204-240-22-00, Carlsbad,
California 92008 (see Figure 1). The site can be conveniently located by the address of 270
Juniper Avenue, Carlsbad, California, 92008. The property is currently improved with a single
story residential structure, a two-story detached garage, concrete driveway, and various
landscape/hardscape. The site is largely undeveloped with a change in grade of approximately 3
feet across the site based on the attached Topographic Survey Map (PLSA Engineering, dated
August 9, 2023). The property is bounded to the north, east, and west by residential property,
and to the south by Juniper Avenue.
2.2 Proposed Development
Based upon review of the “Plan View – Preliminary Grading Plan” by PLSA Engineering and
conversations with you, current site improvements will be demolished to prepare the site for
proposed improvements. The conceptual improvements consist of seven multi-story single family
Project No. 254003-01 B - 5 February 17, 2026GEOTEK
RINCON HOMES Project No. 3944-SD
Preliminary Geotechnical October 26, 2023
Juniper Avenue, Carlsbad, California 92008 Page 2
residential dwellings. The construction is anticipated to consist of a concrete slab on grade, with
perimeter and interior and isolated spread footings, utilizing wood frame construction.
Associated improvements are anticipated to consist of utilities, concrete flatwork/hardscape, and
landscape. Finished pad elevations on the site will range from 51.8 feet to 54.9 feet based upon
the grading plans. After review of the Topographic Survey Map (PLSA Engineering, dated August
9, 2023) and the Preliminary Grading Plans (PLSA Engineering, Sheet 3) it is anticipated that
minimal cuts and fills of less than five feet in height will be required for the site development.
3. FIELD EXPLORATION AND LABORATORY TESTING
3.1 Field Exploration
GeoTek’s field study was conducted on September 4, 2023, and consisted of the excavation of
two exploratory borings advanced with a manual auger. Borings reached practical refusal at 6
feet below existing ground surface. At periodic depths, the boring was qualitatively evaluated
with a soil probe. A representative bulk soil sample was obtained and transported to GeoTek’s
laboratory for engineering analysis. The explorations were logged by an Engineering Geologist
from GeoTek. The approximate locations of exploration locations are presented on the
Geotechnical Map, Figure 2. A description of material encountered in the borings is included in
Logs of Exploration, Appendix A.
Percolation Testing
In addition to the geotechnical exploratory borings, two percolation test borings (Borings P-1 &
P-2) were excavated at the approximate locations presented on the Geotechnical Map, Figure 2,
to depths of about two feet. A ground water table was not encountered within the depths of
the borings performed. After review of “Geotechnical Investigation and Infiltration Testing”
dated July 14, 2021 (Log No. 21469) prepared by Hetherington Engineering, Inc. for the
neighboring site to the northwest, a groundwater table was also not encountered within the
depths of the borings performed, approximately 13.5 feet below grade. Infiltration/percolation
testing was conducted in these borings in general accordance with the requirements of the City
of Carlsbad on August 25, 2023.
The percolation tests consisted of drilling a four-inch diameter test hole to the desired depth and
installing approximately two inches of gravel in the bottom of the hole. A two-inch diameter
perforated PVC pipe, wrapped in a filter sock, was placed in the excavations. Water was then
placed in the borings to presoak the holes and percolation testing was performed following the
Project No. 254003-01 B - 6 February 17, 2026GEOTEK
RINCON HOMES Project No. 3944-SD
Preliminary Geotechnical October 26, 2023
Juniper Avenue, Carlsbad, California 92008 Page 3
pre-soak period. The percolation tests were then performed, which consisted of adding water
to each test hole and measuring the water drop over a 30-minute period. The water drop was
recorded for twelve test intervals. Water was added to the test holes after each test interval.
The field percolation rates were then converted to an infiltration rate using the Porchet Method.
The infiltration rate for each of the borings is presented in the following table.
Boring No. Infiltration Rate (inches per hour) Depth of Boring (inches)
Boring P-1 2.34 24
Boring P-2 2.31 24
The results of the infiltration rates ranged from 2.31 to 2.34 inches per hour at the test locations.
The provided infiltration rates should be utilized for the design of the proposed water disposal
systems. The proposed storm water disposal should be designed in strict conformance with the
manufacturer’s recommendations utilizing an appropriate infiltration rate.
Copies of the infiltration data sheets and completed Approved Infiltration Rate Assessment
Methods forms per the City of Carlsbad BMP Design Manual are presented in Appendix C. No
factors of safety were applied to the rates provided above. Over the lifetime of the infiltration
areas, the infiltration rates may be affected by sediment build up and biological activities, as well
as local variations in near surface soil conditions. A suitable factor of safety should be applied to
the field rate in designing the infiltration system.
It should be noted that the infiltration rates provided above were performed in relatively
undisturbed on-site soils. Infiltration rates will vary and are mostly dependent on the underlying
consistency of the site soils and relative density. Infiltration rates may be impacted by weight of
equipment travelling over the soils, placement of engineered fill and other various factors.
GeoTek assumes no responsibility or liability for the ultimate design or performance of the storm
water facility.
3.2 Laboratory Testing
Laboratory testing was performed on a bulk soil sample collected during the field explorations.
The purpose of the laboratory testing was to evaluate their physical properties for use in
engineering design and analysis. Results of the laboratory testing program, along with a brief
description and relevant information regarding testing procedures, are included in Appendix B.
Project No. 254003-01 B - 7 February 17, 2026GEOTEK
RINCON HOMES Project No. 3944-SD
Preliminary Geotechnical October 26, 2023
Juniper Avenue, Carlsbad, California 92008 Page 4
4. GEOLOGIC AND SOILS CONDITIONS
4.1 Regional Setting
The subject property is located in the Peninsular Ranges geomorphic province. The Peninsular
Ranges province is one of the largest geomorphic units in western North America. Basically, it
extends roughly 975 miles from the north and northeasterly adjacent the Transverse Ranges
geomorphic province to the peninsula of Baja California. This province varies in width from about
30 to 100 miles. It is bounded on the west by the Pacific Ocean, on the south by the Gulf of
California and on the east by the Colorado Desert Province.
The Peninsular Ranges are essentially a series of northwest-southeast oriented fault blocks.
Several major fault zones are found in this province. The Elsinore Fault zone and the San Jacinto
Fault zones trend northwest-southeast and are found in the near the middle of the province. The
San Andreas Fault zone borders the northeasterly margin of the province. The Newport-
Inglewood-Rose Canyon Fault zone meanders the southwest margin of the province. No faults
are shown in the immediate site vicinity on the map reviewed for the area.
4.2 EARTH MATERIALS
Based on a review of published geologic maps and site specific field evaluation, the subject site is
underlain by Old Paralic deposits.
Artificial Fill (Not Mapped)
Although not directly encountered in the explorations existing artificial fill may be encountered
in areas not directly explored or in limited areas. If encountered the artificial fill should be
assumed to be very loose to loose, variable in consistency, and placed in an uncontrolled or
compacted manner that does not comply with current grading ordinances.
Old Paralic Deposits (Map Symbol Qop)
Quaternary-age Old Paralic deposits (Paralics) were encountered in all explorations and was
observed to consist of dark reddish-brown, silty fine sands, moist, very loose at the surface to
dense with depth. Approximately up to the upper three feet are considered to be weathered as
evident by very loose and yielding to the soil probe to a depth of 2.5 feet. Firm and unyielding
Paralics were encountered at a depth of 3 feet and practical refusal was encountered at a depth
of 6 feet.
Based on the laboratory test results, the near surface soils have a “very low” expansion index
(ASTM D 4829). Based on the laboratory test results from “Geotechnical Investigation and
Infiltration Testing” dated July 14, 2021 (Log No. 21469) prepared by Hetherington Engineering,
Project No. 254003-01 B - 8 February 17, 2026
4.2.1
4.2.1
GEOTEK
RINCON HOMES Project No. 3944-SD
Preliminary Geotechnical October 26, 2023
Juniper Avenue, Carlsbad, California 92008 Page 5
Inc. for the neighboring site to the northwest, the near surface soils have a soluble sulfate content
of less than 0.1 percent (ASTM D 4327).
4.3 SURFACE WATER AND GROUNDWATER
Surface Water
Surface water was not observed during the recent site exploration. If encountered during
earthwork construction, surface water on this site will likely be the result of precipitation.
Provisions for surface drainage will need to be accounted for by the project civil engineer.
Groundwater
A static groundwater table was not encountered during exploration of the subject site. After
review of “Geotechnical Investigation and Infiltration Testing” dated July 14, 2021 (Log No.
21469) prepared by Hetherington Engineering, Inc. for the neighboring site to the northwest, a
groundwater table was also not encountered within the depths of the borings performed,
approximately 13.5 feet below grade. The Pacific Ocean and the Aqua Hedionda are located
approximately 1,100 feet to the west and 1,800 feet to south (respectively). Based on
groundwater levels reported in the vicinity of the site (California Department of Water
Resources, Well No. MW-7, located approximately 2,200 feet east of the site), groundwater was
encountered as shallow as 18.4 feet in historic measurements (05/28/2020)
(http://geotracker.waterboards.ca.gov/). Based on the anticipated depth of removals,
groundwater is not anticipated to be a factor in site development. Localized perched
groundwater may be present but is also not anticipated to be a factor in site development.
4.4 EARTHQUAKE HAZARDS
Surface Fault Rupture
The geologic structure of the entire southern California area is dominated mainly by northwest-
trending faults associated with the San Andreas system. The site is in a seismically active region.
No active or potentially active fault is known to exist at this site nor is the site situated within an
“Alquist-Priolo” Earthquake Fault Zone or a Special Studies Zone (Bryant and Hart, 2007). No
faults transecting the site were identified on the readily available geologic maps reviewed. The
nearest known active fault is the Newport Inglewood-Rose Canyon fault located approximately
1.5 miles to the west of the site.
Liquefaction/Seismic Settlement
Liquefaction describes a phenomenon in which cyclic stresses, produced by earthquake-induced
ground motion, create excess pore pressures in relatively cohesionless soils. These soils may
thereby acquire a high degree of mobility, which can lead to lateral movement, sliding,
consolidation and settlement of loose sediments, sand boils and other damaging deformations.
Project No. 254003-01 B - 9 February 17, 2026
4.3.1
4.3.2
4.4.1
4.4.2
GEOTEK
RINCON HOMES Project No. 3944-SD
Preliminary Geotechnical October 26, 2023
Juniper Avenue, Carlsbad, California 92008 Page 6
This phenomenon occurs only below the water table, but, after liquefaction has developed, the
effects can propagate upward into overlying non-saturated soil as excess pore water dissipates.
The factors known to influence liquefaction potential include soil type and grain size, relative
density, groundwater level, confining pressures, and both intensity and duration of ground
shaking. In general, materials that are susceptible to liquefaction are loose, saturated granular
soils having low fines content under low confining pressures.
The liquefaction potential and seismic settlement potential on this site is considered negligible
provided remedial grading recommendations presented herein are completed and due to the
apparent dense nature of underlying shallow Paralic formational material.
Other Seismic Hazards
The potential for landslides and rockfall is considered negligible due to the absence of over
steepened slopes. The potential for secondary seismic hazards such as seiche and tsunami is low,
due to site elevation and published Tsunami inundation maps.
5. CONCLUSIONS AND RECOMMENDATIONS
5.1 General
Development of the site appears feasible from a geotechnical viewpoint provided that the
following recommendations are incorporated in the design and construction phases of the
development. The following sections present general recommendations for currently anticipated
site development plans. If plans change GeoTek should be notified to review the new plans and
determine if supplemental recommendations are prudent.
5.2 EARTHWORK CONSIDERATIONS
General
Earthwork and grading should be performed in accordance with the applicable grading ordinances
of the City of Carlsbad, the 2022 (or current) California Building Code (CBC), and
recommendations contained in this report. Grading Guidelines included in Appendix D outline
general procedures and do not anticipate all site-specific situations. In the event of conflict, the
recommendations presented in the text of this report should supersede those contained in
Appendix D.
Project No. 254003-01 B - 10 February 17, 2026
4.4.3
5.2.1
GEOTEK
RINCON HOMES Project No. 3944-SD
Preliminary Geotechnical October 26, 2023
Juniper Avenue, Carlsbad, California 92008 Page 7
Site Clearing and Preparation
Site preparation should start with removal of all existing improvements and vegetation in conflict
with proposed improvements. These materials should be disposed of properly off site. Any
existing underground improvements, utilities and trench backfill should also be removed or be
further evaluated as part of site development operations.
Remedial Grading
Prior to placement of fill materials and in all structural areas the upper variable, potentially
compressible materials should be removed. Removals should include all undocumented fill soils
and weathered, loose Paralics down to competent, relatively undisturbed, dense, firm and
unyielding Paralics. The lateral extent of removals should be performed five feet beyond the
outside edge of all settlement sensitive structures/foundations or equivalent to that vertically
removed, whichever is greater. The bottom of the removals should be observed by a GeoTek
representative prior to processing the bottom for receiving placement of compacted fills.
Depending on actual field conditions encountered during grading, locally deeper and/or shallower
areas of removal may be necessary.
Where removals are needed adjacent to existing property lines, on-property lines or within a
distance equal to the depth of excavation of offsite structures or foundations, a temporary slope
no steeper than 1:1 (horizontal:vertical) away from the top of the foundation and into the
remedial excavation should be performed.
The resultant voids from remedial grading/over-excavation should be filled with materials placed
in general accordance with the recommendations provided in Section 5.2.4 Engineered Fill of this
report. Prior to placement of engineered fill, the bottom of all removals should be scarified to a
minimum depth of six inches, brought to optimum moisture content, and then compacted to at
least 90% of the soil’s maximum dry density as determined by ASTM D1557 test procedures.
Where engineered fills are placed against temporary excavation slopes, the fill should be benched
into the slope as the fill is brough up to design grades with care. If unstable conditions adjacent
to excavations persists, our office should be contacted for supplemental remedial grading
recommendations.
Engineered Fill
Onsite materials are generally considered suitable for reuse as engineered fill provided, they are
free from vegetation, roots, debris, and rock/concrete or hard lumps greater than six inches in
maximum dimension. The earthwork contractor should have the proposed excavated materials
to be used as engineered fill at this project approved by the soils engineer prior to placement.
Project No. 254003-01 B - 11 February 17, 2026
5.2.2
5.2.3
5.2.4
GEOTEK
RINCON HOMES Project No. 3944-SD
Preliminary Geotechnical October 26, 2023
Juniper Avenue, Carlsbad, California 92008 Page 8
Engineered fill materials should be moisture conditioned to or above optimum moisture content
and compacted in horizontal lifts not exceeding 8 inch in loose thickness to a minimum relative
compaction of 90% as determined by ASTM D1557 test procedures. If fill is being placed on
slopes steeper than 5:1 (h:v), the fill should be properly benched into the existing slopes.
Excavation Characteristics
Excavations in the onsite materials can generally be accomplished with heavy-duty earthmoving
or excavating equipment in good operating condition.
Trench Excavations and Backfill
Temporary excavations within the onsite materials should be stable at 1:1 inclination for short
durations during construction, and where cuts do not exceed 10 feet in height. Temporary cuts
to a maximum height of 4 feet can be excavated vertically.
Trench excavations should conform to Cal-OSHA regulations. The contractor should have a
competent person, per OSHA requirements, on site during construction to observe conditions
and to make the appropriate recommendations.
Utility trench backfill should be compacted to at least 90% relative compaction of the maximum
dry density as determined by ASTM D1557 test procedures. Under-slab trenches should also be
compacted to project specifications.
Onsite materials may not be suitable for use as bedding material but should be suitable as backfill
provided particles larger than 6 inches are removed.
Compaction should be achieved with a mechanical compaction device. Ponding or jetting of
trench backfill is not recommended. If backfill soils have dried out, they should be thoroughly
moisture conditioned prior to placement in trenches.
5.3 DESIGN RECOMMENDATIONS
Foundation Design Criteria
Preliminary foundation design criteria, in general conformance with the 2022 CBC, are presented
herein. These are typical design criteria and are not intended to supersede the design by the
structural engineer. Once actual structural loads and grading concepts are known, supplemental
recommendations may be warranted which may require additional test borings and laboratory
testing.
Project No. 254003-01 B - 12 February 17, 2026
5.2,5
5.2.6
5.3.1
GEOTEK
RINCON HOMES Project No. 3944-SD
Preliminary Geotechnical October 26, 2023
Juniper Avenue, Carlsbad, California 92008 Page 9
Based on visual classification of materials encountered onsite and as verified by laboratory testing,
site soils are anticipated to exhibit a “very low” (Expansion Index (EI) ≤ 20) expansion index per
ASTM D4829. Additional laboratory testing should be performed upon completion of site grading
to verify the expansion potential and plasticity index of the subgrade soils. The preliminary
recommendations are presented below. The structure may be supported on continuous and
spread foundations founded in compacted fill or paralic deposits.
*Code minimums per Table 1809.7 of the 2022 CBC should be complied with.
It should be noted that the above recommendations are based on soil support characteristics
only. The structural engineer should design the slab and beam reinforcement based on actual
loading conditions.
The following recommendations should be implemented into the design:
Preliminarily, an allowable bearing capacity of 2,000 pounds per square foot (psf) may
be considered for design of continuous and perimeter footings that meet the depth
and width requirements in the table above. This value may be increased by 300 psf
for each additional 12 inches in depth and 200 psf for each additional 12 inches in
width to a maximum value of 3,000 psf. Additionally, an increase of one-third may be
applied when considering short-term live loads (e.g., seismic and wind loads).
DESIGN PARAMETERS FOR CONVENTIONALL REINFORCED SHALLOW
FOUNDATIONS
Type of Building 2-Story Wood Framed and Stucco Sided
Expansion Index “Very Low” Expansion Potential
(EI ≤ 20)
Foundation Embedment Depth or
Minimum Perimeter Beam Depth (inches
below lowest adjacent finished grade)
18 - Inches
Minimum Foundation Width for
continuous / perimeter footings* 15 - Inches
Minimum Foundation Width for isolated
/ column footings* 24 – Inches (Square)
Minimum Slab Thickness (actual) 4 inches
Minimum Slab Reinforcing
No. 3 rebar 12” on-center, each way, or
No. 4 bars 18” on-center, each way,
placed in the middle one-third of the slab thickness
Minimum Footing Reinforcement Four No. 4 reinforcing bars,
two top and two bottom
Pre-saturation of Subgrade Soil (percent
of optimum moisture content) Minimum 100% to a depth of 12 inches
Project No. 254003-01 B - 13 February 17, 2026GEOTEK
RINCON HOMES Project No. 3944-SD
Preliminary Geotechnical October 26, 2023
Juniper Avenue, Carlsbad, California 92008 Page 10
Based on experience in the area, structural foundations may be designed in
accordance with 2022 CBC, and to withstand a total settlement of 1 inch and
maximum differential settlement of one-half of the total settlement over a horizontal
distance of 40 feet. Seismically induced settlement is considered to be minimal.
The passive earth pressure may preliminarily be computed as an equivalent fluid having
a density of 200 psf per foot of depth, to a maximum earth pressure of 3,000 psf for
footings founded on engineered fill. A coefficient of friction between soil and
concrete of 0.35 may be used with dead load forces. When combining passive
pressure and frictional resistance, the passive pressure component should be reduced
by one-third.
Grade beams should be utilized across large entrances. The base of the grade beam
should be at the same elevation as the bottom of the adjoining footings.
Under Slab Moisture Membrane
A moisture and vapor retarding system should be placed below slabs-on-grade where moisture
migration through the slab is undesirable. Guidelines for these are provided in the 2022 California
Green Building Standards Code (CALGreen) Section 4.505.2 and the 2022 CBC Section 1907.1
It should be realized that the effectiveness of the vapor retarding membrane can be adversely
impacted as a result of construction related punctures (e.g., stake penetrations, tears, punctures
from walking on the vapor retarder placed atop the underlying aggregate layer, etc.). These
occurrences should be limited as much as possible during construction. Thicker membranes are
generally more resistant to accidental puncture that thinner ones. Products specifically designed
for use as moisture/vapor retarders may also be more puncture resistant. Although the CBC
specifies a 6-mil vapor retarder membrane, it is GeoTek’s opinion that a minimum 10 mil
membrane with joints properly overlapped and sealed should be considered, unless otherwise
specified by the slab design professional.
Moisture and vapor retarding systems are intended to provide a certain level of resistance to
vapor and moisture transmission through the concrete, but do not eliminate it. The acceptable
level of moisture transmission through the slab is to a large extent based on the type of flooring
used and environmental conditions. Ultimately, the vapor retarding system should be comprised
of suitable elements to limit migration of water and reduce transmission of water vapor through
the slab to acceptable levels. The selected elements should have suitable properties (i.e.,
thickness, composition, strength, and permeability) to achieve the desired performance level.
Project No. 254003-01 B - 14 February 17, 2026
5.3.2
GEOTEK
RINCON HOMES Project No. 3944-SD
Preliminary Geotechnical October 26, 2023
Juniper Avenue, Carlsbad, California 92008 Page 11
Moisture retarders can reduce, but not eliminate, moisture vapor rise from the underlying soils
up through the slab. Moisture retarder systems should be designed and constructed in accordance
with applicable American Concrete Institute, Portland Cement Association, Post-Tensioning
Concrete Institute, ASTM and California Building Code requirements and guidelines.
GeoTek does not practice in the field of moisture vapor transmission evaluation/migration since
that practice is not a geotechnical discipline. Therefore, we recommend that a qualified person,
such as the flooring contractor, structural engineer, architect, and/or other experts specializing
in moisture control within the building be consulted to evaluate the general and specific moisture
and vapor transmission paths and associated potential impact on the proposed construction. That
person (or persons) should provide recommendations relative to the slab moisture and vapor
retarder systems and for migration of potential adverse impact of moisture vapor transmission
on various components of the structures, as deemed appropriate. In addition, the
recommendations in this report and GeoTek’s services in general are not intended to address
mold prevention; since GeoTek, along with geotechnical consultants in general, do not practice
in the area of mold prevention. If specific recommendations addressing potential mold issues are
desired, then a professional mold prevention consultant should be contacted.
Miscellaneous Foundation Recommendations
To reduce moisture penetration beneath the slab on grade areas, utility trenches
should be backfilled with engineered fill, lean concrete or concrete slurry where they
intercept the perimeter footing or thickened slab edge.
Spoils from the footing excavations should not be placed in the slab-on-grade areas
unless properly moisture-conditioned, compacted and tested. The excavations should
be free of loose/sloughed materials and be neatly trimmed at the time of concrete
placement.
Foundation Setbacks
Where applicable, the following setbacks should apply to all foundations. Any improvements not
conforming to these setbacks may be subject to lateral movements and/or differential
settlements:
The bottom of all footings for structures near retaining walls should be deepened
so as to extend below a 1:1 projection upward from the bottom inside edge of the
wall stem.
Project No. 254003-01 B - 15 February 17, 2026
5.3.3
5.3.4
GEOTEK
RINCON HOMES Project No. 3944-SD
Preliminary Geotechnical October 26, 2023
Juniper Avenue, Carlsbad, California 92008 Page 12
The bottom of any existing foundations for structures should be deepened so as to
extend below a 1:1 projection upward from the bottom of the nearest excavation.
Seismic Design Parameters
The site is located at approximately 33.151211 degrees north latitude and -117.344942 degrees
west longitude. Site spectral accelerations (Ss and S1), for 0.2 and 1.0 second periods for a risk
targeted two (2) percent probability of exceedance in 50 years (MCER) were determined using
the web interface provided by ASCE/SEI-7 (https://asce7hazardtool.online) to access the USGS
Seismic Design Parameters. Due to the presence of relatively shallow formational material, a Site
Class “C” is considered appropriate for this site. The results, based on ASCE 7-22 and the 2022
CBC, are presented in the following table.
SITE SEISMIC PARAMETERS
Mapped 0.2 sec Period Spectral Acceleration, Ss 1.092g
Mapped 1.0 sec Period Spectral Acceleration, S1 0.394g
Maximum Considered Earthquake (MCER) Spectral
Response Acceleration for 0.2 Second, SMS 1.311g
Maximum Considered Earthquake (MCER) Spectral
Response Acceleration for 1.0 Second, SM1 0.591g
5% Damped Design Spectral Response
Acceleration Parameter at 0.2 Second, SDS 0.874g
5% Damped Design Spectral Response
Acceleration Parameter at 1 second, SD1 0.394g
Site Modified Peak Ground Acceleration (PGAM) 0.579g
Seismic Design Category D
Soil Sulfate Content
Based on the laboratory test results from “Geotechnical Investigation and Infiltration Testing”
dated July 14, 2021 (Log No. 21469) prepared by Hetherington Engineering, Inc. for the
neighboring site to the northwest, the near surface soils have a soluble sulfate content of less
than 0.1 percent by weight, which is considered “S0” as per Table 19.3.1.1 of ACI 318-14. Based
upon the test results provided by Hetherington Engineering, Inc., no special recommendations
for concrete are required for this project due to soil sulfate exposure.
General Concrete Flatwork
It is recommended that control joints be placed in two directions spaced the numeric equivalent
of roughly 24 times the thickness of the slab in inches (e.g., a 4-inch slab would have control joints
at 96 inch [8 feet] centers). These joints are a widely accepted means to control cracks and
should be reviewed by the project structural engineer.
Project No. 254003-01 B - 16 February 17, 2026
5,3.5
5.3.6
5.3.7
GEOTEK
RINCON HOMES Project No. 3944-SD
Preliminary Geotechnical October 26, 2023
Juniper Avenue, Carlsbad, California 92008 Page 13
Presaturation of flatwork subgrade should be verified to be a minimum 100% to a depth of 12
inches.
Retaining Wall Design and Construction
Recommendations presented herein may apply to typical masonry or concrete vertical retaining
walls to a maximum height of 6 feet. Additional review and recommendations should be
requested for higher walls.
Retaining wall foundations embedded a minimum of 12 inches into engineered fill materials should
be designed using an allowable bearing capacity of 2,000 psf. This value may be increased by 300
psf for each additional 12 inches in depth and 200 psf for each additional 12 inches in width to a
maximum value of 3,000 psf.
Retaining wall foundations embedded a minimum of 12 inches into competent formational
bedrock materials (Very Old Paralic Deposits) may be designed using an allowable bearing
capacity of 3,500 psf. This value may be increased by 500 psf for each additional 12 inches in
depth and 200 psf for each additional 12 inches in width to a maximum value of 4,500 psf.
An increase of one-third may be applied when considering short-term live loads (e.g., seismic or
wind loads). The passive earth pressure may be computed as an equivalent fluid having a density
of 250 psf per foot of depth, to a maximum earth pressure of 2,000 psf. A coefficient of friction
between soil/bedrock and concrete of 0.35 may be used with dead load forces. When combining
passive pressure and frictional resistance, the passive pressure component should be reduced by
one-third.
An equivalent fluid pressure approach may be used to compute the horizontal active pressure
against the wall. The appropriate fluid unit weights are given in the table below for specific slope
gradients of imported retained materials.
Surface Slope of
Retained Materials
(H:V)
Equivalent Fluid
Pressure (PCF)
Select Backfill*
Level 40
2:1 55
*Select backfill should consist of imported sand other approved
materials with an SE>30 and an EI<20.
Project No. 254003-01 B - 17 February 17, 2026
5.3.8
GEOTEK
RINCON HOMES Project No. 3944-SD
Preliminary Geotechnical October 26, 2023
Juniper Avenue, Carlsbad, California 92008 Page 14
The above equivalent fluid weights do not include other superimposed loading conditions such
as expansive soil, vehicular traffic, structures, seismic conditions, or adverse geologic conditions.
5.3.9 Wall Backfill and Drainage
Wall backfill should include a minimum one (1) foot wide section of ¾ to 1-inch clean crushed
rock (or approved equivalent). The rock should be wrapped in Mirafi 140N or an approved
equivalent and placed immediately along the back of wall and extend up from the back-drain to
within approximately 12 inches of finish grade. The upper 12 inches should consist of compacted
onsite materials. Alternatively, a manufactured wall drainage product (example: Mira Drain 6000)
may be used for wall drainage. Any such product should be installed in conformance with the
manufacturer’s recommendations. If the walls are designed using the “select” backfill design
parameters, then the “select” materials shall be placed within the active zone as defined by a 1:1
(H:V) projection from the back of the retaining wall footing up to the retained surface behind the
wall. Presence of other materials might necessitate revision to the parameters provided and
modification of wall designs.
The backfill materials should be placed in lifts no greater than eight (8) inches in thickness and
compacted at 90% relative compaction in accordance with ASTM Test Method D 1557. Proper
surface drainage needs to be provided and maintained. Water should not be allowed to pond
behind retaining walls. Waterproofing of site walls should be performed where moisture
migration through the wall is undesirable.
Retaining walls should be provided with an adequate pipe and gravel back drain system to reduce
the potential for hydrostatic pressures to develop. A 4-inch diameter perforated collector pipe
(Schedule 40 PVC, or approved equivalent) in a minimum of one cubic foot per lineal foot of 3/8
to one-inch clean crushed rock or equivalent, wrapped in filter fabric should be placed near the
bottom of the backfill and be directed (via a solid outlet pipe) to an appropriate disposal area.
Maximum horizontal spacing between drain outlets should be 100 feet.
As an alternative to the drain, rock and fabric, a pre-manufactured wall drainage product
(example: Mira Drain 6000 or approved equivalent) may be used behind the retaining wall. The
wall drainage product should extend from the base of the wall to within two (2) feet of the
ground surface. The subdrain should be placed in direct contact with the wall drainage product.
Drain outlets should be maintained over the life of the project and should not be obstructed or
plugged by adjacent improvements.
Project No. 254003-01 B - 18 February 17, 2026GEOTEK
RINCON HOMES Project No. 3944-SD
Preliminary Geotechnical October 26, 2023
Juniper Avenue, Carlsbad, California 92008 Page 15
5.4 POST CONSTRUCTION CONSIDERATIONS
Landscape Maintenance and Planting
Water has been shown to weaken the inherent strength of soil, and slope stability is significantly
reduced by overly wet conditions. Positive surface drainage away from graded slopes should be
maintained and only the amount of irrigation necessary to sustain plant life should be provided
for planted slopes. Controlling surface drainage and runoff and maintaining a suitable vegetation
cover can minimize erosion. Plants selected for landscaping should be lightweight, deep-rooted
types that require little water and are capable of surviving the prevailing climate.
Overwatering should be avoided. The soils should be maintained in a solid to semi-solid state as
defined by the materials Atterberg Limits. Care should be taken when adding soil amendments
to avoid excessive watering. Leaching as a method of soil preparation prior to planting is not
recommended. An abatement program to control ground-burrowing rodents should be
implemented and maintained. This is critical as burrowing rodents can decreased the long-term
performance of slopes.
It is common for planting to be placed adjacent to structures in planter or lawn areas. This will
result in the introduction of water into the ground adjacent to the foundation. This type of
landscaping should be avoided. If used, then extreme care should be exercised with regard to the
irrigation and drainage in these areas. Waterproofing of the foundation and/or subdrains may be
warranted and advisable. We could discuss these issues, if desired, when plans are made available.
Drainage
The need to maintain proper surface drainage and subsurface systems cannot be overly emphasized.
Positive site drainage should be maintained at all times. Drainage should not flow uncontrolled down
any descending slope. Water should be directed away from foundations and not allowed to pond
or seep into the ground adjacent to the footings. Site drainage should conform to Section 1804.4
of the 2022 CBC. Roof gutters and downspouts should discharge onto paved surfaces sloping away
from the structure or into a closed pipe system which outfalls to the street gutter pan or directly
to the storm drain system. Pad drainage should be directed toward approved areas and not be
blocked by other improvements.
5.5 PLAN REVIEW AND CONSTRUCTION OBSERVATIONS
GeoTek recommends that site grading, specifications, retaining wall plans, and foundation plans
be reviewed by this office prior to construction to check for conformance with the
recommendations of this report. Additional recommendations may be necessary based on these
reviews. It is also recommended that GeoTek representatives be present during site grading and
Project No. 254003-01 B - 19 February 17, 2026
5.4.1
5.4 . .2
GEOTEK
RINCON HOMES Project No. 3944-SD
Preliminary Geotechnical October 26, 2023
Juniper Avenue, Carlsbad, California 92008 Page 16
foundation construction to check for proper implementation of the geotechnical
recommendations. The owner/developer should have GeoTek’s representative perform at least
the following duties:
Observe site clearing and grubbing operations for proper removal of unsuitable materials.
Observe and test bottom of removals prior to fill placement.
Evaluate the suitability of on-site and import materials for fill placement and collect soil
samples for laboratory testing when necessary.
Observe the fill for uniformity during placement including utility trenches.
Observe and test the fill for field density and relative compaction.
Observe and probe foundation excavations to confirm suitability of bearing materials.
If requested, a construction observation and compaction report can be provided by GeoTek,
which can comply with the requirements of the governmental agencies having jurisdiction over
the project. GeoTek recommends that these agencies be notified prior to commencement of
construction so that necessary grading permits can be obtained.
6. LIMITATIONS
The scope of this evaluation is limited to the area explored that is shown on the Geotechnical
Map (Figure 2). This evaluation does not and should in no way be construed to encompass any
areas beyond the specific area of proposed construction as indicated to us by the client. The
scope is based on GeoTek’s understanding of the project and the client’s needs, and geotechnical
engineering standards normally used on similar projects in this region.
The materials observed on the project site appear to be representative of the area; however, soil
and bedrock materials vary in character between excavations and natural outcrops, or conditions
exposed during site construction. Site conditions may vary due to seasonal changes or other
factors. GeoTek, Inc. assumes no responsibility or liability for work, testing or recommendations
performed or provided by others.
Since GeoTek’s recommendations are based on the site conditions observed and encountered,
and laboratory testing, GeoTek’s conclusions and recommendations are professional opinions
that are limited to the extent of the available data. Observations during construction are
important to allow for any change in recommendations found to be warranted. These opinions
Project No. 254003-01 B - 20 February 17, 2026GEOTEK
RINCON HOMES Project No. 3944-SD
Preliminary Geotechnical October 26, 2023
Juniper Avenue, Carlsbad, California 92008 Page 17
have been derived in accordance with current standards of practice and no warranty is expressed
or implied. Standards of practice are subject to change with time.
Project No. 254003-01 B - 21 February 17, 2026GEOTEK
RINCON HOMES Project No. 3944-SD
Preliminary Geotechnical October 26, 2023
Juniper Avenue, Carlsbad, California 92008 Page 18
7. SELECTED REFERENCES
American Society of Civil Engineers (ASCE), 2022, “Minimum Design Loads for Buildings and
Other Structures,” ASCE/SEI 7-16.
____, 2021, ASCE-7 Hazard Tool, https://asce7hazardtool.online.
ASTM International (ASTM), “ASTM Volumes 4.08 and 4.09 Soil and Rock.”
Bryant, W.A., and Hart, E.W., 2007, "Fault Rupture Hazard Zones in California, Alquist-Priolo
Earthquake Fault Zoning Act with Index to Earthquake Fault Zones Maps," California
Geological Survey: Special Publication 42.
California Code of Regulations, Title 24, 2022 “California Building Code,” 2 volumes.
California Geological Survey (CGS, formerly referred to as the California Division of Mines and
Geology), 1977, “Geologic Map of California.”
____, 1998, “Maps of Known Active Fault Near-Source Zones in California and Adjacent
Portions of Nevada,” International Conference of Building Officials.
City of Carlsbad, City of Carlsbad BMP Design Manual, Appendix D, dated September 1, 2021.
Hetherington Engineering, Inc., Geotechnical Investigation and Infiltration Testing, 3570 & 3590
Garfield Street, Carlsbad, California, Project No. 9325.1, Dated July 14, 2021.
PLSA Engineering, Topographic Survey Map – 270 Juniper Ave., dated August 9, 2023
____, City of Carlsbad Tentative Tract Map, Sheet 3, Plan View – Preliminary Grading Plan.
Tan, S.S., and Kennedy, M.P., 1996, “Geologic Maps of the Northwestern Part of San Diego
County, California,” California Division of Mines and Geology, OFR-96-02, map scale
1:24,000.
Terzaghi, K. and Peck, R., 1967, “Soil Mechanics in Engineering Practice”, second edition.
Project No. 254003-01 B - 22 February 17, 2026GEOTEK
Rincon Homes
270 Juniper Avenue
Carlsbad, California
APN: 204-240-22-00
Project No. 3944-SD
Figure 1
Site Location
Map
Site Location
Modified from USGS San
Luis Rey 2018 7.5-minute
Topographic Map Sheet
Project No. 254003-01 B - 23 February 17, 2026
1 0 .. 5 0
11000 500 0
1 0 . .5
'
SCALE 1 :24 000
KILOMETERS
METERS
0
MIILES
1 2
1000 2000
1
1000 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 110000 s:::::E;;::::is:======::::i;;;;;;;;;;;;;;;;;;;;;~E====:::::::1;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;i:::::::::::==:::::::~;;;;;;;;;;;;;;;;;;;~E====::::::i;;~;;;;;;;;;;;;;;;;;;3'.:::::::::===::SE;;;;;;;;;;;;;;;;;;;;31
FEET
GEOTEK
Rincon Homes
270 Juniper Avenue
Carlsbad, California
APN: 204-240-22-00
Project No. 3944-SD
Figure 2
Geotechnical
Map
LEGEND
(Locations are Approximate)
Manual Auger
Boring Location
Percolation Test
Location
P-1
HA-1
Old Paralic DepositsQop6-7
HA-1
HA-2
P-1
P-2
Qop6-7
Qop6-7
Approximate Limits of Study
Project No. 254003-01 B - 24 February 17, 2026
-• • •
&.I, ....................
PLAN VIEW -PRELIMINARY GRADING PLAN
CONSTRUCTION NOTES
{DOISIN;--,~l'tl.i'J!lll:lrKfal/N -@~-11Er.-1111U'lRSOISOW
GEOTEK
APPENDIX A
LOGS OF EXPLORATION
Project No. 254003-01 B - 25 February 17, 2026
GEOTEK
RINCON HOMES Project No. 3944-SD
Preliminary Geotechnical October 26, 2023
Juniper Avenue, Carlsbad, California 92008 Page A-1
A - FIELD TESTING AND SAMPLING PROCEDURES
Loose Bulk Samples (Large)
These samples are normally large bags of earth materials over 20 pounds in weight collected
from the field by means of hand digging or exploratory cuttings.
B – BORING/TRENCH LOG LEGEND
The following abbreviations and symbols often appear in the classification and description of soil
and rock on the logs of borings/trenches:
SOILS
USCS Unified Soil Classification System
f-c Fine to coarse
f-m Fine to medium
GEOLOGIC
B: Attitudes Bedding: strike/dip
J: Attitudes Joint: strike/dip
C: Contact line
……….. Dashed line denotes USCS material change
Solid Line denotes unit / formational change
Thick solid line denotes end of boring/trench
(Additional denotations and symbols are provided on the log of borings/trenches)
Project No. 254003-01 B - 26 February 17, 2026
GEOTEK
GeoTek, Inc.
LOG OF EXPLORATORY BORING
SM
BB-1 EI, SR
#
---Small Bulk ---No Recovery ---Water Table
RV = R-Value Test
SR = Sulfate/Resisitivity Test SH = Shear Test CO = Consolidation test MD = Maximum Density
30
LE
G
E
N
D
Sample type: ---Ring ---SPT ---Large Bulk
Lab testing:AL = Atterberg Limits EI = Expansion Index SA = Sieve Analysis
25
20
15
Backfilled with adjacent soil
HOLE TERMINATED AT 6 FEET
10 No groundwater encountered
5
Practical Refusal
Old Paralic Deposits (Qop)
Silty Fine SAND, reddish brown, moist, loose, yields to soil probe 2 feet, weathered
Noticeable resistance in auger advancement, firm and unyielding to soil probe
Dr
y
D
e
n
s
i
t
y
(p
c
f
)
Ot
h
e
r
s
MATERIAL DESCRIPTION AND COMMENTS
Surface: Grass over 2 inches of topsoil over
SAMPLES
US
C
S
S
y
m
b
o
l
BORING NO.: HA-1
Laboratory Testing
De
p
t
h
(
f
t
)
Sa
m
p
l
e
T
y
p
e
Blo
w
s
/
6
i
n
Sa
m
p
l
e
Nu
m
b
e
r
Wa
t
e
r
C
o
n
t
e
n
t
(%
)
LOCATION:Carlsbad, CA ELEVATION:43 feet MSL DATE:9/4/2023
PROJECT NO.:3944-SD HAMMER:RIG TYPE:Manual Auger
PROJECT NAME:270 Juniper DRILL METHOD:Boring OPERATOR:CDL
CLIENT:Rincon Homes DRILLER:GeoTek, Inc.LOGGED BY:CDL
Project No. 254003-01 B - 27 February 17, 2026
-
/ ------
~/\
-------------------------------------------------• I 12] ~ □ ¥-
GeoTek, Inc.
LOG OF EXPLORATORY BORING
SM
#
---Small Bulk ---No Recovery ---Water Table
AL = Atterberg Limits EI = Expansion Index SA = Sieve Analysis RV = R-Value Test
SR = Sulfate/Resisitivity Test SH = Shear Test CO = Consolidation test MD = Maximum Density
30
LE
G
E
N
D
Sample type: ---Ring ---SPT ---Large Bulk
Lab testing:
25
20
15
HOLE TERMINATED AT 6 FEET
10 No groundwater encountered
Backfilled with adjacent soil
Firm and unyielding to the soil probe
5
Practical Refusal
Old Paralic Deposits (Qop)
Silty Fine SAND, reddish brown, moist, loose, yields to soil probe 2 feet, weathered
Noticeable resistance in auger advancement, firm and unyielding to soil probe
Dr
y
D
e
n
s
i
t
y
(p
c
f
)
Ot
h
e
r
s
MATERIAL DESCRIPTION AND COMMENTS
Surface: Grass over 2 inches of topsoil over
SAMPLES
US
C
S
S
y
m
b
o
l
BORING NO.: HA-2
Laboratory Testing
De
p
t
h
(
f
t
)
Sa
m
p
l
e
T
y
p
e
Blo
w
s
/
6
i
n
Sa
m
p
l
e
Nu
m
b
e
r
Wa
t
e
r
C
o
n
t
e
n
t
(%
)
LOCATION:Carlsbad, CA ELEVATION:43 feet MSL DATE:9/4/2023
PROJECT NO.:3944-SD HAMMER:RIG TYPE:Manual Auger
PROJECT NAME:270 Juniper DRILL METHOD:Boring OPERATOR:CDL
CLIENT:Rincon Homes DRILLER:GeoTek, Inc.LOGGED BY:CDL
Project No. 254003-01 B - 28 February 17, 2026
-----------
-------------------------------------------------• I 12] ~ □ ¥-
APPENDIX B
RESULTS OF LABORATORY TESTING
Project No. 254003-01 B - 29 February 17, 2026
GEOTEK
RINCON HOMES Project No. 3944-SD
Preliminary Geotechnical October 26, 2023
Juniper Avenue, Carlsbad, California 92008 Page B-1
SUMMARY OF LABORATORY TESTING
Identification and Classification
Soils were identified visually in general accordance with the standard practice for description and
identification of soils (ASTM D2488). The soil identifications and classifications are shown on the logs of
exploratory trenches in Appendix A.
Expansion Index Test
Expansion Index testing was performed on one sample collected during the subsurface exploration. The
expansion index was determined in general accordance with test method ASTM Test Procedure D 4829.
The test results are presented in Appendix B.
Maximum Density
Laboratory testing was performed on one sample collected during the subsurface exploration for
compaction characteristics. The laboratory maximum dry density and optimum moisture content for the
soil was determined in general accordance with ASTM Test Method D 1557 procedures. The test results
are graphically presented in Appendix B.
Project No. 254003-01 B - 30 February 17, 2026
GEOTEK
MOISTURE/DENSITY RELATIONSHIP
Client:Rincon Homes Job No.:3944-SD
Project:270 Juniper Avenue Lab No.:0
Location:Carlsbad, CA
Material Type:Reddish Brown Silty Sand
Material Supplier:-
Material Source:-
Sample Location:HA-1 BB-1
-
Sampled By:CDL Date Sampled:9/4/2023
Received By:CDL Date Received:9/4/2023
Tested By:CDL Date Tested:9/5/2023
Reviewed By:-Date Reviewed:-
Test Procedure:ASTM D1557 Method:A
Oversized Material (%):0.0 Correction Required: yes x no
MOISTURE CONTENT (%):5.493827 7.95957 9.311224 11.2987 5.493827 7.95957 9.3112245 11.2987
DRY DENSITY (pcf):126.0142 128.7778 130.2136 124.5157
CORRECTED DRY DENSITY (pcf):#DIV/0! #DIV/0! #DIV/0! #DIV/0!
ZERO AIR VOIDS DRY DENSITY (pcf):
MOISTURE DENSITY RELATIONSHIP VALUES
Maximum Dry Density, pcf 134.0 @ Optimum Moisture, %8.5
Corrected Maximum Dry Density, pcf @ Optimum Moisture, %
MATERIAL DESCRIPTION
Grain Size Distribution:Atterberg Limits:
% Gravel (retained on No. 4)Liquid Limit, %
% Sand (Passing No. 4, Retained on No. 200)Plastic Limit, %
% Silt and Clay (Passing No. 200)Plasticity Index, %
Classification:
Unified Soils Classification:
AASHTO Soils Classification:
119
121
123
125
127
129
131
133
135
137
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
DR
Y
D
E
N
S
I
T
Y
,
P
C
F
MOISTURE CONTENT, %
MOISTURE/DENSITY RELATIONSHIP CURVE DRY DENSITY (pcf):
CORRECTED DRY DENSITY (pcf):
ZERO AIR VOIDS DRY DENSITY (pcf)
S.G. 2.7
S.G. 2.8
Poly. (DRY DENSITY (pcf):)
OVERSIZE CORRECTED
ZERO AIR VOIDS
Poly. (S.G. 2.7)
Poly. (S.G. 2.8)
Project No. 254003-01 B - 31 February 17, 2026
GEOTEK
□
•
\ \
\ I\ ~
\ \
I\
I\ \ X
\ I\ ~...-"" I\ "'
1/ ... 'r\. \ \
I\
I/ ' I\ \
' / ' \ \
/ \ I\ I\
i,..-V \
I'\
Ring #: Ring Dia. :Ring Ht.:1"
Weight of compacted sample & ring (gm)
Weight of ring (gm)
Net weight of sample (gm)
Moisture Content, %
Specific Gravity, assumed
Unit Wt. of Water @ 20°C, (pcf)
% Saturation
EXPANSION INDEX =0
820.8 13.4
62.4
50.8 FINAL MOISTURE
Final Weight of wet
sample & tare % Moisture
2.70 9/12/2023 4:30 0.0154 Final
7.8 9/11/2023 3:45 0.0154 Random
1 min/Wet
SATURATION DETERMINATION 9/11/2023 2:46 0.0154 5 min/Wet
Dry Density, lb / ft3 (D/1.F)119.1 9/11/2023 2:41 0.0154
Wet Density, lb / ft3 (C*0.3016)128.4 9/11/2023 2:40 0.0154 10 min/Dry
425.8 9/11/2023 2:30 0.0154 Initial
DENSITY DETERMINATION
796.9 READINGS
371.1 DATE TIME READING
Sample Description:Reddish Brown Silty Sand
1 4.01"
Project Number:3944-SD Date Tested:9/11/2023
Project Location:270 Juniper Sample Source:HA-1, BB-1
EXPANSION INDEX TEST
(ASTM D4829)
Client:Rincon Homes Tested/ Checked By:CDL Lab No
Project No. 254003-01 B - 32 February 17, 2026
GEOTEK
--I
APPENDIX C
PERCOLATION DATA SHEETS & PORCHET CALCULATIONS
CITY OF CARLSBAD BMP DESIGN MANUAL: APPENDIX D FORMS
Project No. 254003-01 B - 33 February 17, 2026
GEOTEK
Job No.: 3944-SD .
Date: 8/25/23 .
After Test: 24" .
Reading
No.Time
Time
Interval
(Min)
Total
Depth of
Hole
(Inches)
Initial
Water
Level
(Inches)
Final
Water
Level
(Inches)
∆ In Water
Level
(Inches)
Comments
1 12:18 30 24 0 17 0
2 12:50 30 24 4.5 21.5 17
3 13:25 30 24 3.5 21 17.5
4 14:05 30 24 4 22 18
5 14:40 30 24 3.75 21.5 17.75
6 15:15 30 24 2 22 20
7 15:45 30 24 1 21 20
8 16:20 30 24 1.5 20 18.5
9 16:55 30 24 1.25 22.5 21.25
10 17:25 30 24 2.75 21 18.25
11 17:55 30 24 1.5 20 18.5
12 18:35 30 24 2 19 17
PERCOLATION DATA SHEET
Project: 270 Juniper ,
Test Hole No.: P-1 Tested By: EM ,
Depth of Hole As Drilled: 24" Before Test: __24"______________________
Project No. 254003-01 B - 34 February 17, 2026
Equation -It =
Havg = (HO+HF)/2 =
It = Inches per Hour
Time Interval, Δt = 30
Client:
Project:
Project No:3945-SD
Date:8/25/2023
Boring No.P-1
Infiltration Rate (Porchet Method)
Rincon Homes
270 Juniper
Final Depth to Water, DF =19.00
Test Hole Radius, r =2.00
Initial Depth to Water, DO =2
2.34
Total Test Hole Depth, DT = 24
ΔH (60r)
Δt (r+2Havg)
HO = DT - DO = 22.00
HF = DT - DF = 5.00
ΔH = ΔD = HO- HF = 17.00
13.50
Project No. 254003-01 B - 35 February 17, 2026
GEOTEK
Job No.: 3944-SD .
Date: 8/25/23 .
After Test: 24" .
Reading
No.Time
Time
Interval
(Min)
Total
Depth of
Hole
(Inches)
Initial
Water
Level
(Inches)
Final
Water
Level
(Inches)
∆ In Water
Level
(Inches)
Comments
1 12:18 30 24 1 23 0
2 12:50 30 24 6.5 18.5 12
3 13:25 30 24 7 20 13
4 14:05 30 24 4.5 21 16.5
5 14:40 30 24 4 19.5 15.5
6 15:15 30 24 3 19 16
7 15:45 30 24 3 19 16
8 16:20 30 24 3 17.5 14.5
9 16:55 30 24 2.5 18.5 16
10 17:25 30 24 4.75 17 12.25
11 17:55 30 24 2.5 18 15.5
12 18:35 30 24 4.5 19.5 15
PERCOLATION DATA SHEET
Project: 270 Juniper ,
Test Hole No.: P-2 Tested By: EM ,
Depth of Hole As Drilled: 24" Before Test: __24"______________________
Project No. 254003-01 B - 36 February 17, 2026
Equation -It =
Havg = (HO+HF)/2 =
It = Inches per Hour
Time Interval, Δt = 30
Client:
Project:
Project No:
Date:
Boring No.
Infiltration Rate (Porchet Method)
270 Juniper
Rincon Homes
3945-SD
8/25/2023
P-2
Final Depth to Water, DF =19.50
Test Hole Radius, r =2.00
Initial Depth to Water, DO =4.5
2.31
Total Test Hole Depth, DT = 24
ΔH (60r)
Δt (r+2Havg)
HO = DT - DO = 19.50
HF = DT - DF = 4.50
ΔH = ΔD = HO- HF = 15.00
12.00
Project No. 254003-01 B - 37 February 17, 2026
GEOTEK
Appendix D: Geotechnical Engineer Analysis
D-1 Sept. 2021
Appendix D Geotechnical Engineer
Analysis
Analysis of Infiltration Restrictions
This section is only applicable if the analysis of infiltration restrictions is performed by a
licensed engineer practicing in geotechnical engineering. The SWQMP Preparer and
Geotechnical Engineer must work collaboratively to identify any infiltration restrictions identified in
Table D.1-1 below. Upon completion of this section, the Geotechnical Engineer must characterize
each DMA as Restricted or Unrestricted for infiltration and provide adequate support/discussion in
the geotechnical report. A DMA is considered restricted when one or more restrictions exist which
cannot be reasonably resolved through site design changes.
Table D.1-1: Considerations for Geotechnical Analysis of Infiltration Restrictions
Restriction Element
Is Element
Applicable?
(Yes/No)
Mandatory
Considerations
BMP is within 100’ of Contaminated Soils
BMP is within 100’ of Industrial Activities Lacking Source Control
BMP is within 100’ of Well/Groundwater Basin
BMP is within 50’ of Septic Tanks/Leach Fields
BMP is within 10’ of Structures/Tanks/Walls
BMP is within 10’ of Sewer Utilities
BMP is within 10’ of Groundwater Table
BMP is within Hydric Soils
BMP is within Highly Liquefiable Soils and has Connectivity to Structures
BMP is within 1.5 Times the Height of Adjacent Steep Slopes (≥25%)
County Staff has Assigned “Restricted” Infiltration Category
Optional
Considerations
BMP is within Predominantly Type D Soil
BMP is within 10’ of Property Line
BMP is within Fill Depths of ≥5’ (Existing or Proposed)
BMP is within 10’ of Underground Utilities
BMP is within 250’ of Ephemeral Stream
Other (Provide detailed geotechnical support)
Result
Based on examination of the best available information,
I have not identified any restrictions above.
Unrestricted
Based on examination of the best available information,
I have identified one or more restrictions above.
Restricted
Table D.1-1 is divided into Mandatory Considerations and Optional Considerations. Mandatory
Project No. 254003-01 B - 38 February 17, 2026
D.1
Appendix D: Geotechnical Engineer Analysis
D-2 Sept. 2021
Considerations include elements that may pose a significant risk to human health and safety and must
always be evaluated. Optional Considerations include elements that are not necessarily associated with
human health and safety, so analysis is not mandated through this guidance document. All elements
presented in this table are subject to the discretion of the Geotechnical Engineer if adequate
supporting information is provided.
Applicants must evaluate infiltration restrictions through use of the best available data. A list of
resources available for evaluation is provided in Section B.2
Determination of Design Infiltration Rates
This section is only applicable if the determination of design infiltration rates is performed
by a licensed engineer practicing in geotechnical engineering. The guidance in this section
identifies methods for identifying observed infiltration rates, corrected infiltration rates, safety factors,
and design infiltration rates for use in structural BMP design. Upon completion of this section, the
Geotechnical Engineer must recommend a design infiltration rate for each DMA and provide
adequate support/discussion in the geotechnical report.
Table D.2-1: Elements for Determination of Design Infiltration Rates
Item Value Unit
Initial Infiltration Rate
Identify per Section D.2.1 in/hr
Corrected Infiltration Rate
Identify per Section D.2.2 in/hr
Safety Factor
Identify per Section D.2.3 unitless
Design Infiltration Rate
Corrected Infiltration Rate ÷ Safety Factor in/hr
Project No. 254003-01 B - 39 February 17, 2026
D.2
Appendix K: Forms and Checklists
K-3 Sept. 2021
Factor of Safety and Design Infiltration Rate
Worksheet Form K-9
Factor Category Factor Description Assigned
Weight (w)
Factor
Value (v)
Product (p)
p = w x v
A Suitability
Assessment
Soil assessment methods 0.25
Predominant soil texture 0.25
Site soil variability 0.25
Depth to groundwater / impervious
layer 0.25
Suitability Assessment Safety Factor, SA = p
B Design
Level of pretreatment/ expected
sediment loads 0.5
Redundancy/resiliency 0.25
Compaction during construction 0.25
Design Safety Factor, SB = p
Combined Safety Factor, Stotal= SA x SB
Observed Infiltration Rate, inch/hr, Kobserved
(corrected for test-specific bias)
Design Infiltration Rate, in/hr, Kdesign = Kobserved / Stotal
Supporting Data
Briefly describe infiltration test and provide reference to test forms:
Project No. 254003-01 B - 40 February 17, 2026
APPENDIX D
GENERAL EARTHWORK GRADING GUIDELINES
Project No. 254003-01 B - 41 February 17, 2026
GEOTEK
GENERAL GRADING GUIDELINES APPENDIX D
Preliminary Geotechnical and Infiltration Evaluation Page D-1
Carlsbad, California Project No. 3944-SD
GENERAL GRADING GUIDELINES
Guidelines presented herein are intended to address general construction procedures for earthwork
construction. Specific situations and conditions often arise which cannot reasonably be discussed in
general guidelines, when anticipated these are discussed in the text of the report. Often unanticipated
conditions are encountered which may necessitate modification or changes to these guidelines. It is our
hope that these will assist the contractor to more efficiently complete the project by providing a
reasonable understanding of the procedures that would be expected during earthwork and the testing
and observation used to evaluate those procedures.
General
Grading should be performed to at least the minimum requirements of governing agencies, Chapters 18
and 33 of the Uniform Building Code, CBC (2019) and the guidelines presented below.
Preconstruction Meeting
A preconstruction meeting should be held prior to site earthwork. Any questions the contractor has
regarding our recommendations, general site conditions, apparent discrepancies between reported and
actual conditions and/or differences in procedures the contractor intends to use should be brought up
at that meeting. The contractor (including the main onsite representative) should review our report
and these guidelines in advance of the meeting. Any comments the contractor may have regarding these
guidelines should be brought up at that meeting.
Grading Observation and Testing
1. Observation of the fill placement should be provided by our representative during grading.
Verbal communication during the course of each day will be used to inform the contractor of
test results. The contractor should receive a copy of the "Daily Field Report" indicating results
of field density tests that day. If our representative does not provide the contractor with these
reports, our office should be notified.
2. Testing and observation procedures are, by their nature, specific to the work or area observed
and location of the tests taken, variability may occur in other locations. The contractor is
responsible for the uniformity of the grading operations; our observations and test results are
intended to evaluate the contractor’s overall level of efforts during grading. The contractor’s
personnel are the only individuals participating in all aspect of site work. Compaction testing
and observation should not be considered as relieving the contractor’s responsibility to properly
compact the fill.
3. Cleanouts, processed ground to receive fill, key excavations, and subdrains should be observed
by our representative prior to placing any fill. It will be the contractor's responsibility to notify
our representative or office when such areas are ready for observation.
4. Density tests may be made on the surface material to receive fill, as considered warranted by
this firm.
5. In general, density tests would be made at maximum intervals of two feet of fill height or every
1,000 cubic yards of fill placed. Criteria will vary depending on soil conditions and size of the fill.
More frequent testing may be performed. In any case, an adequate number of field density tests
should be made to evaluate the required compaction and moisture content is generally being
obtained.
Project No. 254003-01 B - 42 February 17, 2026
GEOTEK
GENERAL GRADING GUIDELINES APPENDIX D
Preliminary Geotechnical and Infiltration Evaluation Page D-2
Carlsbad, California Project No. 3944-SD
6. Laboratory testing to support field test procedures will be performed, as considered warranted,
based on conditions encountered (e.g. change of material sources, types, etc.) Every effort will
be made to process samples in the laboratory as quickly as possible and in progress construction
projects are our first priority. However, laboratory workloads may cause in delays and some
soils may require a minimum of 48 to 72 hours to complete test procedures.
Whenever possible, our representative(s) should be informed in advance of operational changes
that might result in different source areas for materials.
7. Procedures for testing of fill slopes are as follows:
a) Density tests should be taken periodically during grading on the flat surface of the fill,
three to five feet horizontally from the face of the slope.
b) If a method other than over building and cutting back to the compacted core is to be
employed, slope compaction testing during construction should include testing the outer
six inches to three feet in the slope face to determine if the required compaction is
being achieved.
8. Finish grade testing of slopes and pad surfaces should be performed after construction is
complete.
Site Clearing
1. All vegetation, and other deleterious materials, should be removed from the site. If material is
not immediately removed from the site it should be stockpiled in a designated area(s) well
outside of all current work areas and delineated with flagging or other means. Site clearing
should be performed in advance of any grading in a specific area.
2. Efforts should be made by the contractor to remove all organic or other deleterious material
from the fill, as even the most diligent efforts may result in the incorporation of some materials.
This is especially important when grading is occurring near the natural grade. All equipment
operators should be aware of these efforts. Laborers may be required as root pickers.
3. Nonorganic debris or concrete may be placed in deeper fill areas provided the procedures used
are observed and found acceptable by our representative. Typical procedures are similar to
those indicated on Plate G-4.
Treatment of Existing Ground
1. Following site clearing, all surficial deposits of alluvium and colluvium as well as weathered or
creep effected bedrock, should be removed (see Plates G-1, G-2 and G-3) unless otherwise
specifically indicated in the text of this report.
2. In some cases, removal may be recommended to a specified depth (e.g. flat sites where partial
alluvial removals may be sufficient). The contractor should not exceed these depths unless
directed otherwise by our representative.
3. Groundwater existing in alluvial areas may make excavation difficult. Deeper removals than
indicated in the text of the report may be necessary due to saturation during winter months.
4. Subsequent to removals, the natural ground should be processed to a depth of six inches,
moistened to near optimum moisture conditions and compacted to fill standards.
5. Exploratory back hoe or dozer trenches still remaining after site removal should be excavated
and filled with compacted fill if they can be located.
Project No. 254003-01 B - 43 February 17, 2026
GEOTEK
GENERAL GRADING GUIDELINES APPENDIX D
Preliminary Geotechnical and Infiltration Evaluation Page D-3
Carlsbad, California Project No. 3944-SD
Subdrainage
1. Subdrainage systems should be provided in canyon bottoms prior to placing fill, and behind
buttress and stabilization fills and in other areas indicated in the report. Subdrains should
conform to schematic diagrams G-1 and G-5, and be acceptable to our representative.
2. For canyon subdrains, runs less than 500 feet may use six-inch pipe. Typically, runs in excess of
500 feet should have the lower end as eight-inch minimum.
3. Filter material should be clean, 1/2 to 1-inch gravel wrapped in a suitable filter fabric. Class 2
permeable filter material per California Department of Transportation Standards tested by this
office to verify its suitability, may be used without filter fabric. A sample of the material should
be provided to the Soils Engineer by the contractor at least two working days before it is
delivered to the site. The filter should be clean with a wide range of sizes.
4. Approximate delineation of anticipated subdrain locations may be offered at 40-scale plan
review stage. During grading, this office would evaluate the necessity of placing additional
drains.
5. All subdrainage systems should be observed by our representative during construction and prior
to covering with compacted fill.
6. Subdrains should outlet into storm drains where possible. Outlets should be located and
protected. The need for backflow preventers should be assessed during construction.
7. Consideration should be given to having subdrains located by the project surveyors.
Fill Placement
1. Unless otherwise indicated, all site soil and bedrock may be reused for compacted fill; however,
some special processing or handling may be required (see text of report).
2. Material used in the compacting process should be evenly spread, moisture conditioned,
processed, and compacted in thin lifts six (6) to eight (8) inches in compacted thickness to
obtain a uniformly dense layer. The fill should be placed and compacted on a nearly horizontal
plane, unless otherwise found acceptable by our representative.
3. If the moisture content or relative density varies from that recommended by this firm, the
contractor should rework the fill until it is in accordance with the following:
a) Moisture content of the fill should be at or above optimum moisture. Moisture should
be evenly distributed without wet and dry pockets. Pre-watering of cut or removal
areas should be considered in addition to watering during fill placement, particularly in
clay or dry surficial soils. The ability of the contractor to obtain the proper moisture
content will control production rates.
b) Each six-inch layer should be compacted to at least 90 percent of the maximum dry
density in compliance with the testing method specified by the controlling governmental
agency. In most cases, the testing method is ASTM Test Designation D 1557.
4. Rock fragments less than eight inches in diameter may be utilized in the fill, provided:
a) They are not placed in concentrated pockets;
b) There is a sufficient percentage of fine-grained material to surround the rocks;
c) The distribution of the rocks is observed by, and acceptable to, our representative.
5. Rocks exceeding eight (8) inches in diameter should be taken off site, broken into smaller
fragments, or placed in accordance with recommendations of this firm in areas designated
suitable for rock disposal (see Plate G-4). On projects where significant large quantities of
oversized materials are anticipated, alternate guidelines for placement may be included. If
Project No. 254003-01 B - 44 February 17, 2026
GEOTEK
GENERAL GRADING GUIDELINES APPENDIX D
Preliminary Geotechnical and Infiltration Evaluation Page D-4
Carlsbad, California Project No. 3944-SD
significant oversize materials are encountered during construction, these guidelines should be
requested.
6. In clay soil, dry or large chunks or blocks are common. If in excess of eight (8) inches minimum
dimension, then they are considered as oversized. Sheepsfoot compactors or other suitable
methods should be used to break up blocks. When dry, they should be moisture conditioned to
provide a uniform condition with the surrounding fill.
Slope Construction
1. The contractor should obtain a minimum relative compaction of 90 percent out to the finished
slope face of fill slopes. This may be achieved by either overbuilding the slope and cutting back
to the compacted core, or by direct compaction of the slope face with suitable equipment.
2. Slopes trimmed to the compacted core should be overbuilt by at least three (3) feet with
compaction efforts out to the edge of the false slope. Failure to properly compact the outer
edge results in trimming not exposing the compacted core and additional compaction after
trimming may be necessary.
3. If fill slopes are built "at grade" using direct compaction methods, then the slope construction
should be performed so that a constant gradient is maintained throughout construction. Soil
should not be "spilled" over the slope face nor should slopes be "pushed out" to obtain grades.
Compaction equipment should compact each lift along the immediate top of slope. Slopes
should be back rolled or otherwise compacted at approximately every 4 feet vertically as the
slope is built.
4. Corners and bends in slopes should have special attention during construction as these are the
most difficult areas to obtain proper compaction.
5. Cut slopes should be cut to the finished surface. Excessive undercutting and smoothing of the
face with fill may necessitate stabilization.
Keyways, Buttress and Stabilization Fills
Keyways are needed to provide support for fill slope and various corrective procedures.
1. Side-hill fills should have an equipment-width key at their toe excavated through all surficial soil
and into competent material and tilted back into the hill (Plates G-2, G-3). As the fill is elevated,
it should be benched through surficial soil and slopewash, and into competent bedrock or other
material deemed suitable by our representatives (See Plates G-1, G-2, and G-3).
2. Fill over cut slopes should be constructed in the following manner:
a) All surficial soils and weathered rock materials should be removed at the cut-fill
interface.
b) A key at least one and one-half (1.5) equipment width wide (or as needed for
compaction), and tipped at least one (1) foot into slope, should be excavated into
competent materials and observed by our representative.
c) The cut portion of the slope should be excavated prior to fill placement to evaluate if
stabilization is necessary. The contractor should be responsible for any additional
earthwork created by placing fill prior to cut excavation. (see Plate G-3 for schematic
details.)
3. Daylight cut lots above descending natural slopes may require removal and replacement of the
outer portion of the lot. A schematic diagram for this condition is presented on Plate G-2.
4. A basal key is needed for fill slopes extending over natural slopes. A schematic diagram for this
condition is presented on Plate G-2.
Project No. 254003-01 B - 45 February 17, 2026
GEOTEK
GENERAL GRADING GUIDELINES APPENDIX D
Preliminary Geotechnical and Infiltration Evaluation Page D-5
Carlsbad, California Project No. 3944-SD
5. All fill slopes should be provided with a key unless within the body of a larger overall fill mass.
Please refer to Plate G-3 for specific guidelines.
Anticipated buttress and stabilization fills are discussed in the text of the report. The need to stabilize
other proposed cut slopes will be evaluated during construction. Plate G-5 shows a schematic of
buttress construction.
1. All backcuts should be excavated at gradients of 1:1 or flatter. The backcut configuration should
be determined based on the design, exposed conditions, and need to maintain a minimum fill
width and provide working room for the equipment.
2. On longer slopes, backcuts and keyways should be excavated in maximum 250 feet long
segments. The specific configurations will be determined during construction.
3. All keys should be a minimum of two (2) feet deep at the toe and slope toward the heel at least
one foot or two (2%) percent, whichever is greater.
4. Subdrains are to be placed for all stabilization slopes exceeding 10 feet in height. Lower slopes
are subject to review. Drains may be required. Guidelines for subdrains are presented on Plate
G-5.
5. Benching of backcuts during fill placement is required.
Lot Capping
1. When practical, the upper three (3) feet of material placed below finish grade should be
comprised of the least expansive material available. Preferably, highly and very highly expansive
materials should not be used. We will attempt to offer advice based on visual evaluations of the
materials during grading, but it must be realized that laboratory testing is needed to evaluate the
expansive potential of soil. Minimally, this testing takes two (2) to four (4) days to complete.
2. Transition lots (cut and fill) both per plan and those created by remedial grading (e.g. lots above
stabilization fills, along daylight lines, above natural slopes, etc.) should be capped with a
minimum three foot thick compacted fill blanket.
3. Cut pads should be observed by our representative(s) to evaluate the need for overexcavation
and replacement with fill. This may be necessary to reduce water infiltration into highly
fractured bedrock or other permeable zones, and/or due to differing expansive potential of
materials beneath a structure. The overexcavation should be at least three feet. Deeper
overexcavation may be recommended in some cases.
ROCK PLACEMENT AND ROCK FILL GUIDELINES
It is anticipated that large quantities of oversize material would be generated during grading. It’s likely
that such materials may require special handling for burial. Although alternatives may be developed in
the field, the following methods of rock disposal are recommended on a preliminary basis.
Limited Larger Rock
When materials encountered are principally soil with limited quantities of larger rock fragments or
boulders, placement in windrows is recommended. The following procedures should be applied:
1. Oversize rock (greater than 8 inches) should be placed in windrows.
a) Windrows are rows of single file rocks placed to avoid nesting or clusters of rock.
b) Each adjacent rock should be approximately the same size (within ~one foot in
diameter).
Project No. 254003-01 B - 46 February 17, 2026
GEOTEK
GENERAL GRADING GUIDELINES APPENDIX D
Preliminary Geotechnical and Infiltration Evaluation Page D-6
Carlsbad, California Project No. 3944-SD
c) The maximum rock size allowed in windrows is four feet
2. A minimum vertical distance of three feet between lifts should be maintained. Also, the
windrows should be offset from lift to lift. Rock windrows should not be closer than 15 feet to
the face of fill slopes and sufficient space must be maintained for proper slope construction (see
Plate G-4).
3. Rocks greater than eight inches in diameter should not be placed within seven feet of the
finished subgrade for a roadway or pads and should be held below the depth of the lowest
utility. This will allow easier trenching for utility lines.
4. Rocks greater than four feet in diameter should be broken down, if possible, or they may be
placed in a dozer trench. Each trench should be excavated into the compacted fill a minimum of
one foot deeper than the largest diameter of rock.
a) The rock should be placed in the trench and granular fill materials (SE>30) should be
flooded into the trench to fill voids around the rock.
b) The over size rock trenches should be no closer together than 15 feet from any slope
face.
c) Trenches at higher elevation should be staggered and there should be a minimum of
four feet of compacted fill between the top of the one trench and the bottom of the
next higher trench.
d) It would be necessary to verify 90 percent relative compaction in these pits. A 24 to 72
hour delay to allow for water dissipation should be anticipated prior to additional fill
placement.
Structural Rock Fills
If the materials generated for placement in structural fills contains a significant percentage of material
more than six (6) inches in one dimension, then placement using conventional soil fill methods with
isolated windrows would not be feasible. In such cases the following could be considered:
1. Mixes of large rock or boulders may be placed as rock fill. They should be below the depth of
all utilities both on pads and in roadways and below any proposed swimming pools or other
excavations. If these fills are placed within seven (7) feet of finished grade, they may affect
foundation design.
2. Rock fills are required to be placed in horizontal layers that should not exceed two feet in
thickness, or the maximum rock size present, which ever is less. All rocks exceeding
two feet should be broken down to a smaller size, windrowed (see above), or disposed of in
non-structural fill areas. Localized larger rock up to 3 feet in largest dimension may be placed in
rock fill as follows:
a) individual rocks are placed in a given lift so as to be roughly 50% exposed above the
typical surface of the fill ,
b) loaded rock trucks or alternate compactors are worked around the rock on all sides to
the satisfaction of the soil engineer,
c) the portion of the rock above grade is covered with a second lift.
3. Material placed in each lift should be well graded. No unfilled spaces (voids) should be
permitted in the rock fill.
Compaction Procedures
Compaction of rock fills is largely procedural. The following procedures have been found to generally
produce satisfactory compaction.
Project No. 254003-01 B - 47 February 17, 2026
GEOTEK
GENERAL GRADING GUIDELINES APPENDIX D
Preliminary Geotechnical and Infiltration Evaluation Page D-7
Carlsbad, California Project No. 3944-SD
1. Provisions for routing of construction traffic over the fill should be implemented.
a) Placement should be by rock trucks crossing the lift being placed and dumping at its
edge.
b) The trucks should be routed so that each pass across the fill is via a different path and
that all areas are uniformly traversed.
c) The dumped piles should be knocked down and spread by a large dozer (D-8 or larger
suggested). (Water should be applied before and during spreading.)
2. Rock fill should be generously watered (sluiced)
a) Water should be applied by water trucks to the:
i) dump piles,
ii) front face of the lift being placed and,
iii) surface of the fill prior to compaction.
b) No material should be placed without adequate water.
c) The number of water trucks and water supply should be sufficient to provide constant
water.
d) Rock fill placement should be suspended when water trucks are unavailable:
i) for more than 5 minutes straight, or,
ii) for more than 10 minutes/hour.
3. In addition to the truck pattern and at the discretion of the soil engineer, large, rubber tired
compactors may be required.
a) The need for this equipment will depend largely on the ability of the operators to
provide complete and uniform coverage by wheel rolling with the trucks.
b) Other large compactors will also be considered by the soil engineer provided that
required compaction is achieved.
4. Placement and compaction of the rock fill is largely procedural. Observation by trenching
should be made to check:
a) the general segregation of rock size,
b) for any unfilled spaces between the large blocks, and
c) the matrix compaction and moisture content.
5. Test fills may be required to evaluate relative compaction of finer grained zones or as deemed
appropriate by the soil engineer.
a) A lift should be constructed by the methods proposed, as proposed
6. Frequency of the test trenching is to be at the discretion of the soil engineer. Control areas
may be used to evaluate the contractor’s procedures.
7. A minimum horizontal distance of 15 feet should be maintained from the face of the rock fill and
any finish slope face. At least the outer 15 feet should be built of conventional fill materials.
Piping Potential and Filter Blankets
Where conventional fill is placed over rock fill, the potential for piping (migration) of the fine grained
material from the conventional fill into rock fills will need to be addressed.
The potential for particle migration is related to the grain size comparisons of the materials present and
in contact with each other. Provided that 15 percent of the finer soil is larger than the effective pore
size of the coarse soil, then particle migration is substantially mitigated. This can be accomplished with a
well-graded matrix material for the rock fill and a zone of fill similar to the matrix above it. The specific
gradation of the fill materials placed during grading must be known to evaluate the need for any type of
filter that may be necessary to cap the rock fills. This, unfortunately, can only be accurately determined
during construction.
Project No. 254003-01 B - 48 February 17, 2026
GEOTEK
GENERAL GRADING GUIDELINES APPENDIX D
Preliminary Geotechnical and Infiltration Evaluation Page D-8
Carlsbad, California Project No. 3944-SD
In the event that poorly graded matrix is used in the rock fills, properly graded filter blankets 2 to 3 feet
thick separating rock fills and conventional fill may be needed. As an alternative, use of two layers of
filter fabric (Mirafi 700 x or equivalent) could be employed on top of the rock fill. In order to mitigate
excess puncturing, the surface of the rock fill should be well broken down and smoothed prior to
placing the filter fabric. The first layer of the fabric may then be placed and covered with relatively
permeable fill material (with respect to overlying material) 1 to 2 feet thick. The relative permeable
material should be compacted to fill standards. The second layer of fabric should be placed and
conventional fill placement continued.
Subdrainage
Rock fill areas should be tied to a subdrainage system. If conventional fill is placed that separates the
rock from the main canyon subdrain, then a secondary system should be installed. A system consisting
of an adequately graded base (3 to 4 percent to the lower side) with a collector system and outlets may
suffice.
Additionally, at approximately every 25 foot vertical interval, a collector system with outlets should be
placed at the interface of the rock fill and the conventional fill blanketing a fill slope
Monitoring
Depending upon the depth of the rock fill and other factors, monitoring for settlement of the fill areas
may be needed following completion of grading. Typically, if rock fill depths exceed 40 feet, monitoring
would be recommend prior to construction of any settlement sensitive improvements. Delays of 3 to 6
months or longer can be expected prior to the start of construction.
UTILITY TRENCH CONSTRUCTION AND BACKFILL
Utility trench excavation and backfill is the contractor’s responsibility. The geotechnical consultant
typically provides periodic observation and testing of these operations. While efforts are made to make
sufficient observations and tests to verify that the contractors’ methods and procedures are adequate to
achieve proper compaction, it is typically impractical to observe all backfill procedures. As such, it is
critical that the contractor use consistent backfill procedures.
Compaction methods vary for trench compaction and experience indicates many methods can be
successful. However, procedures that “worked” on previous projects may or may not prove effective
on a given site. The contractor(s) should outline the procedures proposed, so that we may discuss
them prior to construction. We will offer comments based on our knowledge of site conditions and
experience.
1. Utility trench backfill in slopes, structural areas, in streets and beneath flat work or hardscape
should be brought to at least optimum moisture and compacted to at least 90 percent of the
laboratory standard. Soil should be moisture conditioned prior to placing in the trench.
2. Flooding and jetting are not typically recommended or acceptable for native soils. Flooding or
jetting may be used with select sand having a Sand Equivalent (SE) of 30 or higher. This is
typically limited to the following uses:
a) shallow (12 + inches) under slab interior trenches and,
b) as bedding in pipe zone.
The water should be allowed to dissipate prior to pouring slabs or completing trench
compaction.
Project No. 254003-01 B - 49 February 17, 2026
GEOTEK
GENERAL GRADING GUIDELINES APPENDIX D
Preliminary Geotechnical and Infiltration Evaluation Page D-9
Carlsbad, California Project No. 3944-SD
3. Care should be taken not to place soils at high moisture content within the upper three feet of
the trench backfill in street areas, as overly wet soils may impact subgrade preparation.
Moisture may be reduced to 2% below optimum moisture in areas to be paved within the upper
three feet below sub grade.
4. Sand backfill should not be allowed in exterior trenches adjacent to and within an area
extending below a 1:1 projection from the outside bottom edge of a footing, unless it is similar
to the surrounding soil.
5. Trench compaction testing is generally at the discretion of the geotechnical consultant. Testing
frequency will be based on trench depth and the contractor’s procedures. A probing rod would
be used to assess the consistency of compaction between tested areas and untested areas. If
zones are found that are considered less compact than other areas, this would be brought to
the contractor’s attention.
JOB SAFETY
General
Personnel safety is a primary concern on all job sites. The following summaries are safety considerations
for use by all our employees on multi-employer construction sites. On ground personnel are at highest
risk of injury and possible fatality on grading construction projects. The company recognizes that
construction activities will vary on each site and that job site safety is the contractor's responsibility.
However, it is, imperative that all personnel be safety conscious to avoid accidents and potential injury.
In an effort to minimize risks associated with geotechnical testing and observation, the following
precautions are to be implemented for the safety of our field personnel on grading and construction
projects.
1. Safety Meetings: Our field personnel are directed to attend the contractor's regularly scheduled
safety meetings.
2. Safety Vests: Safety vests are provided for and are to be worn by our personnel while on the job
site.
3. Safety Flags: Safety flags are provided to our field technicians; one is to be affixed to the vehicle
when on site, the other is to be placed atop the spoil pile on all test pits.
In the event that the contractor's representative observes any of our personnel not following the above,
we request that it be brought to the attention of our office.
Test Pits Location, Orientation and Clearance
The technician is responsible for selecting test pit locations. The primary concern is the technician's
safety. However, it is necessary to take sufficient tests at various locations to obtain a representative
sampling of the fill. As such, efforts will be made to coordinate locations with the grading contractors
authorized representatives (e.g. dump man, operator, supervisor, grade checker, etc.), and to select
locations following or behind the established traffic pattern, preferably outside of current traffic. The
contractors authorized representative should direct excavation of the pit and safety during the test
period. Again, safety is the paramount concern.
Test pits should be excavated so that the spoil pile is placed away from oncoming traffic. The
technician's vehicle is to be placed next to the test pit, opposite the spoil pile. This necessitates that the
fill be maintained in a drivable condition. Alternatively, the contractor may opt to park a piece of
equipment in front of test pits, particularly in small fill areas or those with limited access.
Project No. 254003-01 B - 50 February 17, 2026
GEOTEK
GENERAL GRADING GUIDELINES APPENDIX D
Preliminary Geotechnical and Infiltration Evaluation Page D-10
Carlsbad, California Project No. 3944-SD
A zone of non-encroachment should be established for all test pits (see diagram below). No grading
equipment should enter this zone during the test procedure. The zone should extend outward to the
sides approximately 50 feet from the center of the test pit and 100 feet in the direction of traffic flow.
This zone is established both for safety and to avoid excessive ground vibration, which typically
decreases test results.
50 ft Zone of
Non-Encroachment
50 ft Zone of
Non-Encroachment
Traffic Direction
Vehicle
parked here Test Pit Spoil
pile
Spoil
pile
Test Pit
SIDE VIEW
PLAN VIEW
TEST PIT SAFETY PLAN
10 0 ft Zone of
Non-Encroachment
Slope Tests
When taking slope tests, the technician should park their vehicle directly above or below the test
location on the slope. The contractor's representative should effectively keep all equipment at a safe
operation distance (e.g. 50 feet) away from the slope during testing.
The technician is directed to withdraw from the active portion of the fill as soon as possible following
testing. The technician's vehicle should be parked at the perimeter of the fill in a highly visible location.
Trench Safety
It is the contractor's responsibility to provide safe access into trenches where compaction testing is
needed. Trenches for all utilities should be excavated in accordance with CAL-OSHA and any other
applicable safety standards. Safe conditions will be required to enable compaction testing of the trench
backfill.
All utility trench excavations in excess of 5 feet deep, which a person enters, are to be shored or laid
back. Trench access should be provided in accordance with OSHA standards. Our personnel are
directed not to enter any trench by being lowered or "riding down" on the equipment.
Our personnel are directed not to enter any excavation which;
1. is 5 feet or deeper unless shored or laid back,
2. exit points or ladders are not provided,
3. displays any evidence of instability, has any loose rock or other debris which could fall into the
trench, or
4. displays any other evidence of any unsafe conditions regardless of depth.
Project No. 254003-01 B - 51 February 17, 2026
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GEOTEK
GENERAL GRADING GUIDELINES APPENDIX D
Preliminary Geotechnical and Infiltration Evaluation Page D-11
Carlsbad, California Project No. 3944-SD
If the contractor fails to provide safe access to trenches for compaction testing, our company policy
requires that the soil technician withdraws and notifies their supervisor. The contractor’s
representative will then be contacted in an effort to affect a solution. All backfill not tested due to
safety concerns or other reasons is subject to reprocessing and/or removal.
Procedures
In the event that the technician's safety is jeopardized or compromised as a result of the contractor's
failure to comply with any of the above, the technician is directed to inform both the developer's and
contractor's representatives. If the condition is not rectified, the technician is required, by company
policy, to immediately withdraw and notify their supervisor. The contractor’s representative will then
be contacted in an effort to affect a solution. No further testing will be performed until the situation is
rectified. Any fill placed in the interim can be considered unacceptable and subject to reprocessing,
recompaction or removal.
In the event that the soil technician does not comply with the above or other established safety
guidelines, we request that the contractor bring this to technician’s attention and notify our project
manager or office. Effective communication and coordination between the contractors' representative
and the field technician(s) is strongly encouraged in order to implement the above safety program and
safety in general.
The safety procedures outlined above should be discussed at the contractor's safety meetings. This will
serve to inform and remind equipment operators of these safety procedures particularly the zone of
non-encroachment.
The safety procedures outlined above should be discussed at the contractor's safety meetings. This will
serve to inform and remind equipment operators of these safety procedures particularly the zone of
non-encroachment.
Project No. 254003-01 B - 52 February 17, 2026
GEOTEK
1384 Poinsettia Avenue, Suite A
Vista, California 92083
TYPICAL CANYON
CLEANOUT
STANDARD GRADING
GUIDELINES
ALTERNATES
Original Ground
3’
Loose Surface Materials
PLATE G-1
Finish Grade
3’
Suitable
Material
Suitable
Material
6” Perforated Pipe in 9 cubic feet per Lineal
Foot Clean Gravel Wrapped in Filter Fabric
Construct Benches
where slope exceeds 5:1
Bottom of Cleanout to Be At
Least 1.5 Times the Width of
Compaction Equipment
4 feet typical
Slope to Drain
Original Ground
Loose Surface Materials
Finish Grade
Suitable
MaterialConstruct Benches
where slope exceeds 5:1
Bottom of Cleanout to Be At
Least 1.5 Times the Width of
Compaction Equipment
4 feet typical
Slope to Drain
6” Perforated Pipe in 9 cubic feet
per Lineal Foot Clean Gravel
Wrapped in Filter Fabric
Project No. 254003-01 B - 53 February 17, 2026
TREATMENT ABOVE
NATURAL SLOPES
STANDARD GRADING
GUIDELINES
TYPICAL FILL SLOPE OVER
NATURAL DESCENDING SLOPE
Topsoil
Bedrock
PLATE G-2
Finish Grade
Fill Slope
Daylight Cut
Line per Plan
Project Removal
at 1 to 1
Min. 3 Feet
Compacted Fill
Colluvium
Creep Zone
Minimum 15 Feet Wide
or 1.5 Equipment
Widths for Compaction
Toe of Fill Slope
per Plan
DAYLIGHT CUT AREA OVER
NATURAL DESCENDING SLOPE
Topsoil
Structural Setback
Without Corrective Work
Project Removal
at 1 to 1
Colluvium
Creep Zone
Min.
2 Feet
Minimum 15 Feet Wide
or 1.5 Equipment
Widths for Compaction
Finish Grade
Bedrock
Min. 3 Feet
Compacted Fill
Min.
2 Feet
Compacted Fill
Compacted Fill
1384 Poinsettia Avenue, Suite A
Vista, California 92081-8505
Topsoil
Colluvium
Creep Zone
Project No. 254003-01 B - 54 February 17, 2026
~
GEOTEK
COMMON FILL
SLOPE KEYS
STANDARD GRADING
GUIDELINES
TYPICAL FILL SLOPE OVER
CUT SLOPE
Topsoil
Bedrock
PLATE G-3
Finish Grade
2: 1 Fill Slope
4’ Typical
Colluvium
Creep Zone
Minimum 15 Feet Wide
or 1.5 Equipment
Widths for Compaction
Toe of Fill Slope
per Plan
TYPICAL FILL SLOPE
Bedrock or
Suitable Dense Material
Minimum compacted fill required
to provide lateral support.
Excavate key if width or depth
less than indicated in table above
Cut Slope
SLOPE
HEIGHT
MIN. KEY
WIDTH
MIN. KEY
DEPTH
5
10
15
20
25
>25
7
10
15
15
15
SEE TEXT
1
1.5
2
2.5
3
CONTRACTOR TO VERIFY
WITH SOIL ENGINEER
PRIOR TO CONSTRUCTION
1384 Poinsettia Avenue, Suite A
Vista, California 92081-8505
Project No. 254003-01 B - 55 February 17, 2026
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) > > >) >) >)) ►)) >))) >))) >))) > >) >)))))) >) > >) > > > >))) >) > >) >) >) >) >) >))) >)) > > > >))) > >) > > > > ►) ► > > C ( C <:CC C ( C <: C < ( ( C <: ( ( C < C < C ( C ( C < C ( C < C (CC ( ( C (<CC CCC C < ( C < C < C ( C ( C < C <CC C ( ( ( C < C ( C <: ( ( ( <: C ( C ( C < C <: C
>) > > >) > >),) >) >))) >) >)),)),)), >))),)))),) > >)))))) >)))))) >))) >) >))) >))))) >) >) >) >) >) >) > > >) >) >) > < ( ( < ( < ( < ( < ( ,( < ,( (,(CC ( C ( < ( ( ( ( ( ( < ( C ( C ( ( ( ( ( ( ( ( ( < ( C ( ( ( < < ( < ( < ( ( ( < < ( C ( ( C ( ( ( C ( < ( C ( < < C ( ( ( ( ,( ( ,( ( ,( ( :«:<:<<<<<<<<<<<<<<<,:<<<<<<«:,:<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<«
NOTES:
1)SOIL FILL OVER WINDROW SHOULE BE 7 FEET OR PER JURISDUICTIONAL STANDARDS AND SUFFICIENTFOR FUTURE EXCAVATIONS TO AVOID ROCKS
2)MAXIMUM ROCK SIZE IN WINDROWS IS 4 FEET MINIMUM DIAMETER
3)SOIL AROUND WINDROWS TO BE SANDY MATERIAL SUBJECT TO SOIL ENGINEER ACCEPTANCE
4)SPACING AND CLEARANCES MUST BE SUFFICIENT TO ALLOW FOR PROPER COMPACTION
5)INDIVDUAL LARGE ROCKS MAY BE BURIED IN PITS.
ROCK BURIAL
DETAILS
STANDARD GRADING
GUIDELINES
PLATE G-4
SEE NOTE 1
15’
MIN.3’ MIN.
3’ MIN.
MINIMUM 15’ CLEAR OR
1.5 EQUIPMENT WIDTHS
FOR COMPACTION
STAGGER ROWS
HORIZONTALLY
NO ROCKS IN
THIS ZONE
CROSS SECTIONAL VIEW
FINISH GRADE
FILL SLOPE
PLAN VIEW
FILL SLOPE
MINIMUM 15’ CLEAR OR 1.5 EQUIPMENT
WIDTHS FOR COMPACTION
MINIMUM 15’ CLEAR OR 1.5 EQUIPMENT
WIDTHS FOR COMPACTION
PLACE ROCKS END TO END
DO NOT PILE OR STACK ROCKS
SOIL TO BE PLACE AROUND AND OVER ROCKS THEN FLOODED INTO
VOIDS. MUST COMPACT AROUND AND OVER EACH ROCK WINDROW
1384 Poinsettia Avenue, Suite A
Vista, California 92081-8505
Project No. 254003-01 B - 56 February 17, 2026
----~ -------------------~------------
c---------_______ t __ _
~--------.t----------.-ii-~-◄.=-----------.►·'11111111!1J
6” Perforated Pipe in 6 cubic
feet per lineal foot clean gravel
wrapped in filter fabric outlet
pipe to gravity flow
BEDROCK COMPACTED FILL
MIN. 3 FEET
COMPACTED FILL
TERRACE DRAIN
AS REQUIRED
2
1
MIN. 15 FEET WIDE OR 1.5 EQUIPMENT
WIDTHS FOR COMPACTION
MIN. 2 FEET
EMBEDDMENT
1384 Poinsettia Avenue, Suite A
Vista, California 92083
Typical Buttress and
Stabilization Fill PLATE G-5
4” or 6” Perforated Pipe in 6 cubic
feet per lineal foot clean gravel
wrapped in filter fabric outlet pipe
to gravity flow at 2% min.
Project No. 254003-01 B - 57 February 17, 2026
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TRANSITION &
UNDERCUT LOTS PLATE G-6
TRANSITION LOT
PROPSED FINISH GRADE
COMPETENT MATERIAL
4’MIN.
OVEREXCAVATE AND
RECOMPACT
PROPOSED STRUCTURE
COMPACTED FILL
3 1
OVEREXCAVATION AND BENCHING NOT
TO EXCEED INCLINATION OF 3:1 (H:V)
UNDERCUT LOT
PROPSED FINISH GRADE
PROPOSED STRUCTURE
4’MIN.
COMPETENT MATERIAL
COMPACTED FILL
OVEREXCAVATE AND
RECOMPACTOVEREXCAVATION TO HAVE 1%
FALL TOWARD FRONT OF LOT
Notes:
1.Removed/overexcavated soils should be recompacted in accordance with recommendations included in the text of the report.
2.Location of cut/fill transition should verified in the field during site grading.
STANDARD GRADING
GUIDELINES1384 Poinsettia Avenue, Suite A
Vista, California 92081-8505
Project No. 254003-01 B - 58 February 17, 2026
-----------------------------r
n
ClJ:OTEK
GEOTECHNICAL | ENVIRONMENTAL | MATERIAL
March 24, 2025
Revised April 4, 2025
Project No. 3944-SD
Rincon Homes
5315 Avenida Encinas, Suite 200
Carlsbad, California 92008
Attention: Mr. Tom St. Claire
Subject: Response to Third-Party Review Comments
Proposed Residential Development
270 Juniper Avenue
Carlsbad, California 92008
Reference: See Page 8
Dear Mr. St. Claire:
As requested, GeoTek, Inc. (GeoTek) has prepared this letter to provide supplemental response
to the City of Carlsbad’s third-party geotechnical review comments by Ninyo & Moore and plan
review (first review) by True North Compliance Services and redline comments of GeoTek’s
“Preliminary Geotechnical, Propose Residential Development, 270 Juniper Avenue, Carlsbad,
California, 92008,” dated October 26, 2023 report and the “Updated Onsite Infiltration
Recommendations, Propose Residential Development, 270 Juniper Avenue, Carlsbad, California,
92008,” dated June 7, 2024. A copy of the geotechnical and plan review comments have been
included as Appendix A and B.
Ninyo & Moore Geotechnical Review Comments
Review Comment No. 1
The Consultant should provide a statement regarding the impact of the proposed grading and construction
on adjacent properties and improvements.
Response to Review Comment No. 1
Project No. 254003-01 B - 60 February 17, 2026
GeoTek, Inc.
1384 Poinsettia Avenue, Suite A Vista, CA 92081-8505
(760) 599-0509 Office (760) 599-0593 f;i www.geotekusa.com
Response to Third-Party Review Comments March 24, 2025, Revised April 4, 2025
270 Juniper Avenue Project No. 3944-SD
Carlsbad, California Page 2
The proposed development is considered feasible from a geotechnical standpoint. Grading and
foundation plans should take into account the appropriate geotechnical features of the site.
Provided that the recommendations presented in the referenced geotechnical evaluation report,
this document, and good construction practices are utilized during design and construction, the
proposed construction is not anticipated to adversely impact the adjacent properties from a
geotechnical standpoint.
Review Comment No. 2
Per the City of Carlsbad’s (1993) guidelines, the Geotechnical Consultant is to provide recommendations
for the reinforcing of exterior concrete flatwork.
Response to Review Comment No. 2
GeoTek provided geotechnical recommendations for exterior concrete flatwork in section 5.3.7
General Concrete Flatwork of GeoTek’s 2023 report. The recommendations remain valid
(reinforcement from a geotechnical aspect is not recommended) and is limited to patios, private
sidewalks, non-vehicular loading concrete supported on very low expansive engineered fill. For
concrete influenced by vehicle loads GeoTek defaults to reinforcement of concrete designed by
the project’s structural engineer of record.
Review Comment No. 3
The City of Carlsbad BMP design Manual (2024) has been updated since the issuance of the refenced
geotechnical report (GeoTek, 2023). The Geotechnical Consultant should review and indicate if their
infiltration recommendations are still valid and applicable.
Response to Review Comment No. 3
The City of Carlsbad BMP Design Manual Appendix D – Geotechnical Engineer Analysis section,
dated January 2, 2024 was reviewed and has been revised and is included in Appendix C.
Review Comment No. 4
The referenced grading plans (PLSA, 2025) include “Typical Detail – Permeable Pavers” depict a
permeable paver section that is to support vehicle loading. Since a recommended vehicular paver section
was not provided in the referenced geotechnical report (GeoTek, 2023), the Geotechnical Consultant
should review this detail and indicate if the section is suitable or not from a geotechnical standpoint.
Response to Review Comment No. 4
Permeable interlocking concrete pavement for passenger vehicles, services vehicles, and
emergency fire access (72,000-pound fire engine) should consist of 3 1/8-inch thick (minimum)
Project No. 254003-01 B - 61 February 17, 2026GEOTEK
Response to Third-Party Review Comments March 24, 2025, Revised April 4, 2025
270 Juniper Avenue Project No. 3944-SD
Carlsbad, California Page 3
concrete pavers (with edge restraints and sand filled joints) underlain by bedding sand layer (for
leveling), compacted base layer, and compacted subbase layer. Materials for use as bedding
course, base and subbase base should meet the following specifications in Table – 1.
TABLE 1
PERMEABLE INTERLOCKING CONCRETE PAVEMENT
Material Layer Thickness Specification
Bedding Course 2-inch ASTM No. 8 Stone
Joint Filler Not Applicable ASTM No. 8 Stone
Base 4-inches ASTM No. 57 stone
Subbase 6-inches ASTM No. 2 stone
The base and subbase should be compacted to a minimum of 90-pecent of the maximum dry
density as determined by ASTM: D 1557. Prior to placement of aggregate base, the underlying
subgrade soils should be scarified to a depth of 12-inches and compacted to 90-percent relative
compaction.
Review Comment No. 5
The Geotechnical Consultant should review the project grading and foundation plans and provide any
additional geotechnical recommendations, as appropriate, and indicate if the plans have been prepared
in accordance with the geotechnical recommendations provided in the referenced geotechnical report
(GeoTek, 2023) and referenced infiltration letter (GeoTek, 2024).
Response to Review Comment No. 5
GeoTek has completed a geotechnical review of the referenced grading and structural plans.
Based on this review, it is GeoTek’s opinion that the provided and reviewed plans have been
prepared utilizing the soil engineering design parameters and recommendations provided in the
referenced report. These plans are considered to be geotechnically suitable. GeoTek makes no
representation as to the accuracy of calculations or structural design provided on the referenced
structural plan.
Project No. 254003-01 B - 62 February 17, 2026GEOTEK
Response to Third-Party Review Comments March 24, 2025, Revised April 4, 2025
270 Juniper Avenue Project No. 3944-SD
Carlsbad, California Page 4
True North Plan Review Comments
Plan Review Comment S1
Provide the geotechnical engineer’s stamp and signature on the foundation plan an all sheets containing
foundation details confirming that the foundation plan, details, and specifications have been reviewed and
that it has been determined that the recommendations in the geotechnical report are properly
incorporated into the plans.
Response to Plan Review Comment S1
GeoTek has completed a geotechnical review of the referenced structural plans. Based on this
review, it is GeoTek’s opinion that the provided and reviewed plans have been prepared utilizing
the soil engineering design parameters and recommendations provided in the referenced report.
These plans are considered to be geotechnically suitable. GeoTek makes no representation as
to the accuracy of calculations or structural design provided on the referenced structural plan.
This review should be considered in lieu of GeoTek signing and stamping the plans, which are
signed and sealed by the project’s structural engineer of record.
Plan Review Comment S2
Provide addendum letter from the geotechnical engineer to confirm the following:
a) The recommended w/c ratio.
b) As multiple outdated codes are referenced in the report, provide an update letter, confirming
the soils report recommendation are still valid with the newly adopted codes, (ACI 318-19,
CBC 2022, ASCE 7-16,…).
Response to Plan Review Comment S2
a) As sulfate content of the soil has been evaluated to be categorized as S0, geotechnical
recommendations for water-cement ration for a concrete mix design is not considered
necessary and GeoTek defaults to the structural engineer of record for the project, which
recommends a maximum water-cement ratio of 0.40 (Gouvis, Sheets S-1.1, S-2.1, S-3.1,
and S-4.1, Note for Concrete Mix).
b) This letter shall be considered an update letter and GeoTek’s reported recommendations
(GeoTek, 2023 and 2024) remain valid.
Project No. 254003-01 B - 63 February 17, 2026GEOTEK
Response to Third-Party Review Comments March 24, 2025, Revised April 4, 2025
270 Juniper Avenue Project No. 3944-SD
Carlsbad, California Page 5
Redline Review Comment
Response
Additional percolation testing was performed. See “Updated Onsite Infiltration
Recommendations, Proposed Residential Development, 270 Juniper Avenue, Carlsbad, California
92008,” revised date March 26, 2025, included in Appendix C.
Redline Review Comment
Response
Project No. 254003-01 B - 64 February 17, 2026
Rincon Homes
SJISAwnid&Enctnu.~lOO
Carbbad. Cufornia 92008
Attention Hr.TomSt.ClaN
June 7, 101◄ Project No, 39◄◄-SO
Updaced Oneke lnlltradon Recommendations
Proposed ftesldandal Owe,opment
270).nperA'MIIIN w, .. .,o,r ,..,,,~;t..,.,:1._,,,
Clrist,ad,caMomla9lOOI i--e,..Jts,,,.,,. ~..,, .. T,1 ..,.,
Our-Hr.St.Claire:
"64,ff\•,,y ¥ ~Q.F.,r ..J<..,_
"".,.,,,_, G.oM.--....,. ,, ,>tt .. f'JJ,,~
GeoTllk. Inc. (G.oTN) underAandl dllt die propoJed BMPs associated with the development
of the subject ffle are planned to be.·
Permeable pawn for the common drMway
•Underp-ound,,.,kno.l
• Undlrz,ound vauk. no. l
• Rats.ct liknoon pint.-.
RINCON HOHES
Prclimlnvy Geotechoical
/
pre-soak period. The percolatlon tescs were then performed, which consisted or ad<lina W}.ter
ro each te.sc hole and measuring the w,ncr drop over a JO-minute period. The '•'•<uer drop was
recorded for twelve test Intervals. Water was added to the test hole,s after each ten interval
The field pc?rco/atfon rates were then converted to an lnflltratlon rate using the, Porchet Method:
The lnnltration r.ite, for each of the borings is presented In the following table.
Borin No.
Bori P-1
Borl P-2
lnflltradon Rate lnche1
2.H
2.31
~~(\ ,..,F•....r.t..';"'I.~ .... -.,,rt-;-,,..r A-: "-"..,.._.-;-'l. ..,. i~ 1-;e..._.._
The results of the Jnf'Utn.tfon rates ranged from 2.3 I to 2.34 inches per hour at the test locations.
The provided inftltradon rates should be utilized for the deslgn of the proposed water disposal
S)'ltems. The pr0pOHcf storm war.er disposal should be designed in strict conformance with the
manufacturer's recommendations utilizing an appropriate Infiltration rate.
Copies of the lnftkradon data sheets and completed Approved Infiltration Rate Assessment
Methods forms per the Ocy of Carlsbad BMP Design Manual are presented in Appendix C. No
facton of safety were appNed to the ~tes provided above. Over the lifetime of the infiltration
areas. the infiltration rates may be affected by sediment build up and biological activities, as well as local variations in near SUfUCe SOil conditions. A sui
GEOTEK
Response to Third-Party Review Comments March 24, 2025, Revised April 4, 2025
270 Juniper Avenue Project No. 3944-SD
Carlsbad, California Page 6
Percolation testing results and infiltration rates have been added to the revised report. See
“Updated Onsite Infiltration Recommendations, Proposed Residential Development, 270 Juniper
Avenue, Carlsbad, California 92008,” revised date March 26, 2025, included in Appendix C. It is
GeoTek’s opinion that percolation test locations P-1 through P-4 are adequate to characterize
infiltration rates for the reported BMP’s.
Redline Review Comment
Response
Remedial grading should include removals of all undocumented fill soils and weathered, loose
Paralics down to competent, relatively undisturbed Paralics. Removal depths on the order of 2
to 3-feet below existing grades are anticipated.
Redline Review Comment
Project No. 254003-01 B - 65 February 17, 2026
RJNCON HOMES p,,.JiminlryGeotechnlaJ
.llt'iPtr Avenue Adsbad G,ijfnrnJa 22008
5.2.2 Site Clearing and Prepar.uion
P~ec:, Na J'4'1-.SO
Octob@,26.2021 ....,
Site pref»n.tlon should surt with remo'llll or all existing lmprovemenu 11nc;1 vegetation In conflla
with proposed lmpro>1ements. These materials should be disposed of properly off site. Any
exinlng unde,iround improvements, utlUties :md trench backflll should also be remove(! or be further evaluated as part of site development open.lions.
5.2.3 Remedial Gnidlna
Prior to pl.:icemvit of fill materials and In all structural areas the upper v;iriable, potentially
comprenible 111,11terials should be removed. Removals should include all undocumented fill soils ~ . ..,.i'
and weathered, loose Paralks down to competent, relu/vely undisturbed, dense, firm and ~, • ...,.~
unylekMni Parafics. The later.II extent of remo'lills should be performed five feet beyond the w "'1
oumde edp of all Ntdenimc NJnSldve structures/foundations or equivalent to that vertically ;;N:~-~ wflkhewr Is.....,.. The bottom of the removals should be observed by a Geo T ek ""--·" t;.
rep,esentadve prior to JlfOCealn& ct. bottom for receiving placement of compacted fills. ~ on actual fWd condltlonl encountered during gr.iding. locally deeper and/or shallower arwurANfflO\'llma,bentce1ar7.
Where removals ue Medtcf adlacent: to ex1ning property lines, on-property lines or within a
distance~ to the dapdt d extaWldon of offslte structures or foundations, a temporary slope
no stNper than 1:1 ~ away from the top of the foundation and into the ---.. -
The resultant voids Iron, namedlal arwinwOYer-excavation should be filled with materials placed
In genero accordance wtdl the f'IICOfl'lnlancs provided in Stttion 5.2.4 Englneell(f All of this
report. PriOf' to placemant d ...,,...,_Ill.the bottom of all removals should be scarified to a
minimum depth of sbr Inches. bnclutht ID ~ mobrure content, and then compacted to at
lean 90X ofdte solrs maximum dry densft:)' 11 ~ by ASTH D1557 test procedures.
Where engineered fills are placed -,am temporary IICClvatlon slopes, the fill should be benched
into the slope u the rm is brou&fl up to cfesl&n ,..._ wkh care, If unstable conditions adjacent
to excavaaons persists, our office shcud be Conacted for supplemenal remedial grading recommendauons.
~ ,W,,,,....,,.,.~dSU/clf
GEOTEK
GeotKhnicol
Maf>
G IIE OTEK
Response to Third-Party Review Comments March 24, 2025, Revised April 4, 2025
270 Juniper Avenue Project No. 3944-SD
Carlsbad, California Page 7
Response
See “Updated Onsite Infiltration Recommendations, Proposed Residential Development, 270
Juniper Avenue, Carlsbad, California 92008,” revised date March 26, 2025, included in Appendix
C.
Updated Foundation Design Recommendations
The following recommendations supersede those presented in the Preliminary Geotechnical
Report by GeoTek dated October 26, 2023. The following table has been updated to take into
account building structures up to 3-storys in height.
*Code minimums per Table 1809.7 of the 2022 CBC should be complied with.
DESIGN PARAMETERS FOR CONVENTIONALL REINFORCED SHALLOW
FOUNDATIONS
Type of Building 3-Story Wood Framed and Stucco Sided
Expansion Index “Very Low” Expansion Potential
(EI ≤ 20)
Foundation Embedment Depth or
Minimum Perimeter Beam Depth (inches
below lowest adjacent finished grade)
24 - Inches
Minimum Foundation Width for
continuous / perimeter footings* 18 - Inches
Minimum Foundation Width for isolated
/ column footings* 36 – Inches (Square)
Minimum Slab Thickness (actual) 4 inches
Minimum Slab Reinforcing
No. 3 rebar 12” on-center, each way, or
No. 4 bars 18” on-center, each way,
placed in the middle one-third of the slab thickness
Minimum Footing Reinforcement Four No. 4 reinforcing bars,
two top and two bottom
Pre-saturation of Subgrade Soil (percent
of optimum moisture content) Minimum 100% to a depth of 12 inches
Project No. 254003-01 B - 66 February 17, 2026GEOTEK
Response to Third-Party Review Comments March 24, 2025, Revised April 4, 2025
270 Juniper Avenue Project No. 3944-SD
Carlsbad, California Page 8
Closure
Should you have any questions after reviewing this supplementary letter, please feel free to
contact our office at your convenience.
Respectfully submitted,
GeoTek, Inc.
Enclosure:
Appendix A – Third-Party Geotechnical Review
Appendix B – City of Carlsbad Plan Review
Appendix C – Updated Onsite Infiltration Recommendations
REFERENCES
City of Carlsbad, 2016, “City of Carlsbad BMP Design Manual,” Second Update to the February
16, 2016 Manual, Effective January 11, 2023.
GeoTek, Inc., In-house proprietary information.
Geotek, Inc. 2022, “Preliminary Geotechnical [Evaluation], Proposed Residential Development,
270 Juniper Avenue, Carlsbad, California,” Project No. 3944-SD, dated October 26, 2023.
_____, 2024, “Updated Onsite Infiltration Recommendations, Proposed Residential
Development, 270 Juniper Avenue, Carlsbad, California 92008, dated June 7, 2024, Revised
March 26, 2025.
Christopher D. Livesey
CEG, 2733 Exp. 05/31/25
Vice President
Edwin R. Cunningham
RCE 81687, Exp. 03/31/26
Project Engineer
Project No. 254003-01 B - 67 February 17, 2026GEOTEK
APPENDIX A
Third-Party Geotechnical Review and Red Line Comments 2-25-2025
Project No. 254003-01 B - 68 February 17, 2026GEOTEK
Project No. 254003-01 B - 69 February 17, 2026
Gtoteehnlcal & Envlronm,ntal Science■ Con1u1t1nlll
February 25, 2025
Project No. 109343026
Ms. Jessica Nishiura, PE
Hunsaker & Associates San Diego, Inc.
9707 Waples Street
San Diego, California 92121
Subject: Third-Party Geotechnical Review
Juniper Coast Homes
270 Juniper Avenue, Carlsbad, California
Dear Ms. Nishiura:
At your request, we have prepared this letter providing our review comments to the referenced
geotechnical report prepared by GeoTek, Inc. dated October 26, 2023. Our comments regarding
the project geotechnical report (GeoTek, 2023) include the following:
Comment 1: The Consultant should provide a statement regarding the impact of the proposed
grading end construction on adjacent properties and improvements.
Comment 2: Per the City of Carlsbad's (1993) guidelines, the Geotechnical Consultant is to
provide recommendations for the reinforcing of exterior concrete fletwork.
Comment 3: The City of Carlsbad BMP Design Manual (2024) has been updated since the
issuance of the referenced geotechnicel report (GeoTek, 2023). The Geotechnical Consultant
should review end indicate if their infiltration recommendations are still valid and applicable.
Comment 4: The referenced grading plans (PLSA. 2025) include "Typical Detail -Permeable
Pavers" depict a permeable paver section that is to support vehicle loading. Since a
recommended vehicular paver section was not provided in the referenced geotechnical report
(Geo Tek, 2023), the Geotechnical Consultant should review this detail and indicate if the section
is suitable or not from a geotechnical standpoint.
Comment 5: The Geotechnicel Consultant should review the project grading and foundation
plans and provide any additional geotechnicel recommendations, as appropriate, and indicate if
the plans have been prepared in accordance with the geotechnical recommendations provided
in the referenced geotechnical report (GeoTek, 2023) and referenced infiltration letter (GeoTek,
2024).
5710 Ruffin Road I San Diego, California 92123 Ip. 858.576.1000 I www.ninyoandmoore.com
Project No. 254003-01 B - 70 February 17, 2026
REFERENCES
American Society of Civil Engineers (ASCE), 2017, Minimum Design Loads for Buildings and Other
Structures, ASCE 7-16.
California Building Standards Commission, 2022, California Building Code (CBC), Title 24, Part 2,
Volumes 1 and 2.
City of Carlsbad, 1993, Technical Guidelines For Geotechnical Reports: dated January.
City of Carlsbad, 2022, Engineering Standards, Volume 1 and Volume 3, 2022 Edition: dated
May 30.
City of Carlsbad, 2024, BMP Design Manual, Appendices: dated January 2.
GeoTek, Inc., 2023, Preliminary Geotechnical, Proposed Residential Development, 270 Juniper
Avenue, Carlsbad, California, Project No. 3944-SD: dated October 26.
GeoTek, Inc., 2024, Updated Onsite Infiltration Recommendations, Proposed Residential
Development, 270 Juniper Avenue, Carlsbad, California 92008, Project No. 3944-SD: dated
June 7.
PLSA, 2025, City of Carlsbad, Precise Grading Plans, Juniper Coast Homes, 270 Juniper Avenue,
Carlsbad California, Project No. CT-2023-0005.
Nlnyo & Moore I 270 Juniper Avenue, Carlsbad, California I 109343026 I February 25, 2025
Project No. 254003-01 B - 71 February 17, 2026
1384 Poinsettia Avenue, Suite A Vista CA 9208
GEOTEK
(760) 599-0509 • (760) 599-0593 r) I ~asos
www.geotekusa.com
Rincon Homes
5315 Avenida Encinas, Suite 200
Carlsbad, California 92008
Attention: Mr. Tom St. Claire
June 7, 2024
Project No. 3944-SD
Subject: Updated Onsite Infiltration Recommendations
Proposed Residential Development
270 Juniper Avenue
Carlsbad, California 92008
Dear Mr. St. Claire:
)"1LL. .,, 0 ~ I A.J F, ,_~ ft 4-n .. _,v
F e1-t.S, a-,'-I "iy ~,.,. ... 'f rl .-6t'f"
l-.>~4'i\•,N ¥° l'f""Q..eE (..,Jf°\..1-
<-"' Jl't l C t'1 C~/l.A• it/r"uf f S f'/luf~Jr,O
n>"-\ 11.JF tc..'t ~~•/I' ~
Geo Tek, Inc. (Geo Tek) understands that the proposed BMPs associated with the development
of the subject site are planned to be:
• Permeable pavers for the common driveway
• Underground vault no. I
• Underground vault no. 2
• Raised filtration planters
This letter is being submitted to provide updated design recommendations for the management
of onsite stormwater. Recommendations regarding onsite management of stormwater supersede
those presented by Geo T ek' s 2022 report.
GeoTek's previous preliminary geotechnical evaluation report (GeoTek, 2023) advanced two
percolation borings, P-1 and P-2, were excavated and tested to identify infiltration characteristics.
GEOTECHNICAL I ENVIRONMENT
Project No. 254003-01 B - 72 February 17, 2026
RINCON HOMES
Project No. 3944-SD
Preliminary Geotechnical
October 26, 2023
J!lniper Avenue, Carlsbad, California 92008
Page
3 pre-soak period. The percol~tion tests were then performe~, which consisted of adding water to each test hole and measuring the water drop over a 30-mmute period. The water drop was recorded for twelve test intervals. Water was added to the test holes after each test interval. The field percolation rates were then converted to an infiltration rate using the Porchet Method.
The infiltration rate for each of the borings is presented in the following table.
Borin No. Infiltration Rate th of Borin Boring P-1 2.34
24 Sorin P-2 2.31
24 .A~O I "1 F' •~ ftA'.\• ,J ~ \,.--iv (' A"i \f~v c-'r -Z.. * ,~ \,..,,c '-'-The results of the infiltration rates ranged from 2.31 to 2.34 inches per hour at the test locations. The provided infiltration rates should be utilized for the design of the proposed water disposal systems. The proposed storm water disposal should be designed in strict conformance with the manufacturer's recommendations utilizing an appropriate infiltration rate.
Copies of the infiltration data sheets and completed Approved Infiltration Rate Assessment Methods forms per the City of Carlsbad BMP Design Manual are presented in Appendix C. No factors of safety were applied to the rates provided above. Over the lifetime of the infiltration areas, the infiltration rates may be affected by sediment build up and biological activities, as well as local variations in near surface soil conditions. A suitable factor of safety should be applied to the field rate in designing the infiltration system.
It should be noted that the infiltration rates provided above were performed in relatively undisturbed on-site soils. Infiltration rates will vary and are mostly dependent on the underlying consistency of the site soils and relative density. Infiltration rates may be impacted by weight of equipment travelling over the soils, placement of engineered fill and other various factors. Geo T ek assumes no responsibility or liability for the ultimate design or performance of the storm
water facility.
3.2 Laboratory Testing
Laboratory testing was performed on a bulk soil sample collected during the field explorations. The purpose of the laboratory testing was to evaluate their physical properties for use in engineering design and analysis. Results of the laboratory testing program, along with a brief description and relevant information regarding testing procedures, are included in Appendix B.
Project No. 254003-01 B - 73 February 17, 2026
RINCON HOMES .
p liminary Geotechmcal
;~~er Avenue, Carlsbad, California 92008
5.2.2 Site Clearing and Preparation
Project No. 3944 _SD
October 26, 2023
Page 7
Site preparation should start with removal of all existing improvements and vegetation in conflict with proposed improvements. These materials should be disposed of properly off site. An existing underground improvements, utilities and trench backfill should also be removed or b: further evaluated as part of site development operations.
5.2.3 Remedial Grading
Prior to placement of fill materials and in all structural areas the upper variable, potentially compressible materials should be removed. Removals should include all undocumented fill soils ~fl,..,....,,. and weathered, loose Paralics down to competent, relatively undisturbed, dense, firm and A.J,,uf'~., unyielding Paralics. The lateral extent of removals should be performed five feet beyond the 'J>E ~ outside edge of all settlement sensitive structures/foundations or equivalent to that vertically .(!_';~,."'""" removed, whichever is greater. The bottom of the removals should be observed by a Geo T ek GM~. JV c; _ representative prior to processing the bottom for receiving placement of compacted fills. Depending on actual field conditions encountered during grading, locally deeper and/or shallower areas of removal may be necessary.
Where removals are needed adjacent to existing property lines, on-property lines or within a distance equal to the depth of excavation of offsite structures or foundations, a temporary slope no steeper than I: I (horizontal:vertical) away from the top of the foundation and into the remedial excavation should be performed.
The resultant voids from remedial grading/over-excavation should be filled with materials placed in general accordance with the recommendations provided in Section 5.2.4 Engineered Fill of this report. Prior to placement of engineered fill, the bottom of all removals should be scarified to a minimum depth of six inches, brought to optimum moisture co ntent, and then compacted to at least 90% of the soil's maximum dry density as determined by ASTM D 1557 test procedures.
Where engineered fills are placed against temporary excavation slopes, the fill should be benched into the slope as the fill is brough up to design grades with care. If unstable conditions adjacent to excavations persists, our office should be contacted for su pplemental remedial grading recommendations.
5.2.4 Engineered Fill
Onsite materials are generally considered suitable for reuse as engineered fill provided, they are free from vegetation, roots, debris, and rock/concrete or hard lumps greater than six inches in maximum dimension. The earthwork contractor should have the proposed excavat ed m at erial s to be used as engineered fill at this project approved by the soils engineer prior to placement.
GEOT E K
/.
/
Project No. 254003-01 B - 74 February 17, 2026
LEGEND
(,.,,,,_,. .,.,Apptu,tma/
•
•
Manual Auger
Boring Location
Percolation Test
Location
Old Paralic Deposits
c...;. -:--.....;. -:--.....;. Approximate Limits of Study
---
Pt.AN VIEW· PREUMINARY GRADING Pl.AN
CONSTRUCTION NO TES
Rincon Homes
2 70 Juniper Avenue
Carlsbad, California
APN: 204-240-22-00
Project No . 3944-SD
Figure 2
Geotechnical
Map
GEOTE K
APPENDIX B
City of Carlsbad Plan Review Comments 3-10-2025
Project No. 254003-01 B - 75 February 17, 2026GEOTEK
True North Compliance Services, Inc.
8369 Vickers Street, Suite 207, San Diego, CA 92111
T | 562.733.8030
March 10, 2025
City of Carlsbad City of Carlsbad– FIRST REVIEW
Community Development Department - Building Division City Permit No: PC2025-0012
1635 Faraday Ave. True North No.: 25-018-170
Carlsbad, CA 92008
Plan Review: Construction of 21 Unit Condominiums
Address: 270 Juniper Ave, Carlsbad CA
Applicant Name: Kirk Moeller Applicant Email: kirk@kmarchitectsinc.com
True North Compliance Services, Inc. has completed the review of the following documents for the project
referenced above on behalf of the City of Carlsbad. Our comments can be found on the attached list.
1. Drawings: Electronic copy dated February 13, 2025, by Kirk Moeller Architects, Inc.
2. Structural Calculations: Electronic copy dated January 23, 2025, by Gouvis Engineering.
3. Geotechnical Report: Electronic copy dated October 26, 2023, by Geotek, inc.
Attn: Permit Technician, the scope of work on the plans has been reviewed for coordination with the scope of
work on the permit application. See below for information if the scope of work on plans differs from the permit
application:
Valuation: Confirmed
Scope of Work: Confirmed
Floor Area: Confirmed
Our comments follow on the attached list. Please call if you have any questions or if we can be of further
assistance.
Sincerely,
True North Compliance Services
Non-Structural Review By: Mohammad Afaneh - Plan Review Engineer
Structural Review By: Mulham Hweidi - Plan Review Engineer
Quality Review By: Alaa Atassi - Plan Review Engineer
Project No. 254003-01 B - 76 February 17, 2026
True orth
'/. COMPLIANCE SERVICES
Construction of 21 Unit Condominiums City of Carlsbad– FIRST REVIEW
270 Juniper Ave City Permit No.: PC2025-0012
March 6, 2025 True North No.: 25-018-170
Page 2
Plan Review Comments
HARD COPY - RESUBMITTAL INSTRUCTIONS:
Please do not resubmit plans until all departments have completed their reviews. For status, please
contact building@carlsbadca.gov
Please make all corrections, as requested in the correction list. Submit FOUR new complete sets of plans
for commercial/industrial projects (THREE sets of plans for residential projects). Corrected sets can be
submitted as follows:
Deliver THREE corrected sets of plans and TWO corrected calculations/reports directly to the City
of Carlsbad Building Division, 1635 Faraday Ave., Carlsbad, CA 92008, (442) 339-2719. The city
will route the plans to True North, Planning and Land Development Engineering Departments (if
applicable) for continued review.
Note: If this project requires FIRE PREVENTION review, ensure that you follow their specific
instructions for resubmittal review. The city will not route plans back to Dennis Grubb &
Associates for continued Fire Prevention review.
GENERAL INFORMATION:
A. The following comments are referred to the 2022 California Building, Mechanical, Plumbing, Electrical
Codes, California Green Building Standards Code, and Energy Code (i.e., 2021 IBC, UMC, UPC, and 2020
NEC, as amended by the State of California).
B. There may be other comments generated by the Building Division and/or other City departments that will
also require your attention and response. This attached list of comments, then, is only a portion of the plan
review. Contact the City for other items.
C. Respond in writing to each comment by marking the attached comment list or creating a response letter.
Indicate which details, specification, or calculation shows the required information. Your complete and
clear responses will expedite the re-check.
D. Where applicable, be sure to include the architect and engineer’s stamp and signature on all sheets of the
drawings and on the coversheets of specifications and calculations per CBPC 5536.1 and CBPC 6735. This
item will be verified prior to plan approval.
E. If you have any questions regarding the Non-Structural comments below, please contact Mohammad
Afaneh via email mohammada@tncservices.com or telephone (562) 733-8030.
F. If you have any questions regarding the Structural comments below, please contact Mulham Hweidi via
email mulhamh@tncservices.com or telephone (562) 733-8030.
OCCUPANCY & BUILDING SUMMARY:
Occupancy Groups: R2
Occupant Load: NA
Type of Construction: V-B
Sprinklers: Yes
Stories: 3
MEPT
MEPT
Project No. 254003-01 B - 77 February 17, 2026
Construction of 21 Unit Condominiums City of Carlsbad– FIRST REVIEW
270 Juniper Ave City Permit No.: PC2025-0012
March 6, 2025 True North No.: 25-018-170
Page 3
Area of Work (sq. ft.): 61,845 sq. ft.
ARCHITECTURAL COMMENTS:
A1. Revise cover sheet,
a) Specify NFPA 13 to be installed in all R2 dwelling in order to use the area specification liststed in
CBC 506.2. and CBC 504.4.
b) If the fire sprinkler system remains 13R, the limits on the allowable area and stories are 7,000 sq.
ft. and 2 stories per CBC Table 506.2 and CBC Table 504.4.Which the project exceeds both.
c) For all units, per the Energy reports, a photovoltaic system is required. Note the following on the
cover sheet of the plans:
i) The photovoltaic system will be under a separate permit and plan check and be sized per
the Title 24 Energy Report on this permit.
ii) The photovoltaic plans shall be submitted and approved prior to the rough electrical
inspection.
iii) This permit will not be finalized until the photovoltaic permit is finalized.
d) List all HERS inspection features and special features required. Please coordinate with the Energy
Report.
e) Add “Demo if existing structure” to the list of separate permits.
A2. Revise sheet A1.1,
a) It appears the buildings will be analyzed as separate buildings. Please revise plans to show the
location of imaginary lines between buildings per CBC 705.3.
PLBG
PLBG
T24
Project No. 254003-01 B - 78 February 17, 2026
TYPE OF CONSTRUCTION;
OCCUPANCY:
OCCUPANT LOAD:
DESCRIPTION OF USE:
EXISTING USE:
rULLY SPRINKLERED:
FIRE ALARM:
STANDPIPES:
STORIES;
HEIGHT;
AI.LOWABLE FLOOR:
V-6
R-2 I U (PRIVATE GA RAG ES)
RESIDENTIAL
RESIDENTIAL
NFPA 13D AT DUPLEX BLDG.
NEPA 13 AI TRIPLEX AND OUADPLEX BLDGS
NO
NO
3
30'--0'MAX.
21,000SF
AI.LOWABLE AREA (SPRINKLERED NFPA 13, TYPE V-B, R-2 OCCUPA CY)
TOBE REMOVED
<o
DENSE
TREES
A2.
A2.
A2.
A2.
A2.
A2.
A2.
A3.
A3
A4.
AfJ.
AfJ.
"' <o"' 1
I
I o '1
I
Construction of 21 Unit Condominiums City of Carlsbad– FIRST REVIEW
270 Juniper Ave City Permit No.: PC2025-0012
March 6, 2025 True North No.: 25-018-170
Page 4
b) Check and provide calculation for the allowed opening percentage as per CBC Table 705.8.
c) Check exterior walls for dwellings facing each other on both adjacent and opposite sides, to meet
the 1-hr fire rated wall. CBC Table 705.5.
d) Check projections (eaves and deck) to meet the fire separation distance and fire rating required by
CBC 705.2.
e) Cover sheet specifies 5 visitors parking while plan shows two only.
f) Coordinate with public work for encroachment permit.
A3. Where exterior walls are required to be fire-rated per CBC Table 705.5, parapets in accordance with CBC
705.11 are required.
a) Revise the plan to show 1-hour fire-rated parapet construction in accordance with 705.11.1.
b) Alternatively, update the plans to comply with the exceptions for CBC 705.11.
A4. For all units, specify the exact use for the area under the stairs. If usable, specify space to be protected with
½” gypsum board per CBC 1011.7.3, Exception.
A5. At each unit, dimension the distance from the most the remote point at the third floor to the exit door at the
first floor, and verify the common path of egress travel does not exceed the allowable distance specified in
CBC Table 1006.
A6. The proposed units are built with garages. Accordingly, Separation is required between the dwellings and
the garage. Revise the plans to provide the following information for all Units; provide construction
details to show compliance and cross reference them on the site plan sheet A1.1:
a) Specify the walls separating the dwelling and the garage to be provided with ½” minimum gypsum
board applied on interior side. CBC 406.3.2.
b) Specify garage ceiling to have 5/8” type x gyp board.
c) Door 100A to be self-closing and self-latching.
A7. Provide protective barrier, such as bollards or wheel barrier, where gas appliances, such as furnace, dryers,
or water heaters, are in the normal path of vehicles per CMC 305.1.1
Project No. 254003-01 B - 79 February 17, 2026
Construction of 21 Unit Condominiums City of Carlsbad– FIRST REVIEW
270 Juniper Ave City Permit No.: PC2025-0012
March 6, 2025 True North No.: 25-018-170
Page 5
A8. Sheet A6.2, identify the tempered windows per CBC 2406.
A9. Stamp sheet 1 of grading plans from the soils engineer.
ACCESSIBILITY COMMENTS:
D1. Unassigned and visitor parking spaces. When parking is provided for covered multifamily dwellings and
is not assigned to a resident or a group of residents, then the following comments apply. Please show
compliance:
a) At least 5 percent of the parking spaces shall be accessible and provide access to grade-level
entrances of covered multifamily dwellings and facilities (e.g., swimming pools, clubhouses,
recreation areas, and laundry rooms) that serve covered multifamily dwellings.
b) Accessible parking spaces shall be provided with signage as required by CBC 1109A.8.8. Such
signage shall not be blocked from view by a vehicle parked in the space. CBC 1109A.5.
Project No. 254003-01 B - 80 February 17, 2026
1f2"
J
\ I
1...
lN:S IUl-?<tVt:.NI
:cONDIT/QN.
JR EROSION CONTROL
:ACH WORKING DA
SILT AND OTHER
VERAGE OF GRADE
:y PUNCH STRAW
'TROl HANDBOOK
...!=.&_
VE EXERCISED
3 OF 1HE BUSINES
RDS.
• CITY OF CARLSBAD
JECT DESIGN.
\ld -~~ I
6'-3 1/'2" 1'•7"
I
I
1... _J
5'-.8, 7/8"
3 - - - -
__ _,
(THIS AREA INCLUDES BUT IS NOT LIMITED TO OFF-SITE WORK INCLUDING PUBLJC
IMPROVEMENTS AND TEMPORARY DISTURBANCE SUCH AS VEHICLE AND EQUIPMENT
STAGING AREAS. CONSTRUCT/ON TRENCHES. BACKFILL CUTS AND SLOPE KEYWAYS)
I, EDWIN CUNNINGHAM A REGISTERED CNIL ENGINEER OF THE STATE OF CALIFORNIA, PRINCIPALLY
DOING BUSINESS IN THE FIELD OF APPLIED SOILS MECHANICS, HEREBY CERTIFY THAT A SAMPLING AND
STUDY OF THE SOIL CONDITIONS PREVALENT WITHIN THIS SITE WAS MADE BY ME OR UNDER MY
DIRECTION ON SEPTEMBER 4 2023. TWO COPIES OF THE SOIL REPORT COMPILED FROM THIS STUDY,
WITH MY RECOMMENDATIONS, HAS BEEN SUBMITTED TO THE OFFICE OF THE CITY ENGINEER.
SIGNED:~GEno~rE~K~INmc~. ---------
PHONE NUMBER: (760) 599-0509
G.EJP.E. NO.:--"'""'----------
DATE: ____________ _
STORMWATER REQUIREMENTS THAT APPLY:
□ STANDARD STORMWA1ER REQUIREMENTS ~ PRIORITY PROJECT REQUIREMENTS
EXEMPT FROM
TRASH CAPTURE?
□ YES cg] NO
EXEMPT FROM
HYDROMOD/FICATION? IZI YES D NO
L
Construction of 21 Unit Condominiums City of Carlsbad– FIRST REVIEW
270 Juniper Ave City Permit No.: PC2025-0012
March 6, 2025 True North No.: 25-018-170
Page 6
D2. On sheet A1-1, address the following comments:
a) Specify the accessible route to be 5% maximum running slope with 2% maximum cross slope per
CBC 1113A.1.2 and 1113A.3.
b) Show detectable warning where the accessible route crosses or adjoins the vehicular path of travel
per CBC 1116A.5.
i) Provide a detail for the detectable warnings showing compliance with 11B-705. CBC
1116A.5
c) Specify the accessible path of travel to be at least 48” wide. CBC 1113A.1.1
D3. 5% of the ground units are required to be accessible, please revise and locate accessible units per CBC 11A.
a) 21 units required 2 unite to be accessible, plans show unit 15 only.
D4. At the passenger loading zone, provide an accessible passenger loading zone per CBC 1127A,
a) Provide one accessible loading zone in every continuous 100 feet. Specify the overall length of the
passenger drop off area.
b) Show a minimum width of 60” for the access aisle.
c) The access aisle shall extend the full length of the vehicle pull-up space. The vehicle pull-up space
is required to be a minimum of 20 feet long.
d) Provide marking for the loading zone.
e) Specify the running slope of the loading zone to be 2% maximum.
ELEC
Project No. 254003-01 B - 81 February 17, 2026
:X
TOTAL SPACES REQUIRED:
PRIVATE GARAGE: (2 CAR GARAGE X 21 RESIDENCES) 42 SP.
VISITOR SPACES: (0.25 X 17 RESIDENCES, 4 BLDG C UNITS ELIMINATED WlTH WAIVER) 5SP.
TOTAL SPACES REQUIRED: 47 SPACES
TOTAL SPACES PROVIDED:
TOTAL THIRD FLOOR AREA PROV
TOTAL BUILDING AREA PROVIDE(
BLOG. C UNITS 12-15 COMPLY Wll
TOTAL FIRST FLOOR AREA PROV!
TOTAL SECOND FLOOR AREA. PRI
TOTAL THIRD FLOOR AREA PROV
TOTAL BUILDING AREA PROVIDE(
SLOGS. D & D UNITS 16-21 COMPL
Construction of 21 Unit Condominiums City of Carlsbad– FIRST REVIEW
270 Juniper Ave City Permit No.: PC2025-0012
March 6, 2025 True North No.: 25-018-170
Page 7
MECHANICAL COMMENTS:
M1. Provide a duct support detail. CMC 603.7.
M2. Air ducts shall exhaust 3’-0” from property line and 3’-0” from openings into the building. CMC 504.5.
Even when note “7” specifies the above, dimensions on the plans appear to be less than 3ft; Please revise
to confirm that Air ducts terminate at 3ft from PL and 3ft from openings by showing dimensions on the
plans where applicable.
ELECTRICAL COMMENTS:
E1. Provide transformer specifications and weight, locate housekeeping pad, and provide anchorage details and
calculations per ASCE 7-16.
E2. Provide a GFCI receptacle on each side of the island counter in the kitchen. CEC 210.52(C)(1).
E3. Stamp all electrical sheets
MECH
ELEC
Project No. 254003-01 B - 82 February 17, 2026
:DR00M 3
---
90 SFBMP
PLANTER #13;
57.2·FG
Construction of 21 Unit Condominiums City of Carlsbad– FIRST REVIEW
270 Juniper Ave City Permit No.: PC2025-0012
March 6, 2025 True North No.: 25-018-170
Page 8
PLUMBING COMMENTS:
P1. Overflow roof drains shall terminate in an area where they will be readily visible and will not cause damage
to the building. If the roof drain terminates through a wall, the overflow drain shall terminate 12" minimum
above the roof drain. City Policy 84-35
GREEN BUILDING COMMENTS:
G1. Identify the number of residential EV Parking . Ensure compliance with CGBSC 4.106.4.2. and
CGBSC 5.106.5.3
G2. Provide bicycle parking spaces per CGBSC 5.106.4.
ENERGY COMPLIANCE COMMENTS:
T1. Revise the T-24 forms to be registered as they should be registered, signed by both the Documentation
Author and the Responsible Designer.
PLBG
ELEC
T24
Project No. 254003-01 B - 83 February 17, 2026
nWFLLING I INILRE:C.F!;!TAC.I F C.OUNTFR.T02...S~C.E:S.JN T~E K.IT..C.~_FN_JNJ
,.
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j (UTll'l('.AllOll(OtMlWIQ•IWIMUlJ-.-111,11,(-rQ)MII\Wll(f-
=....-:-----l-161911AI
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Construction of 21 Unit Condominiums City of Carlsbad– FIRST REVIEW
270 Juniper Ave City Permit No.: PC2025-0012
March 6, 2025 True North No.: 25-018-170
Page 9
STRUCTURAL COMMENTS:
General:
S1. Provide the geotechnical engineer’s stamp and signature on the foundation plan and all sheets containing
foundation details confirming that the foundation plan, details, and specifications have been reviewed and
that it has been determined that the recommendations in the geotechnical report are properly incorporated
into the plans.
S2. Provide an addendum letter from the geotechnical engineer to confirm the following:
a) The recommended w/c ratio.
b) As multiple outdated codes are referenced in the report, provide an update letter, confirming the
soils report recommendation are still valid with the newly adopted codes, (ACI 318-19, CBC 2022,
ASCE 7-16,…).
S3. Sheet SN1,
a) Under design criteria, provide a section for the soil values, coordinate with soils report
recommendations.
S4. Sheet SN1.1,
a) Under the reinforced concrete notes,
i) Revise note 4, to designate the cement type. Coordinate with soils report findings.
ii) Designate the w/c ratio.
b) Provide information on the slab on grade.
i) As per section 5.3.2 of the geotechnical report, provide a 10-mil vapor retarder with joints
properly overlapped and sealed.
S5. Roof framing plans and roof details show the roof system to be vaulted roof rafters.
a) Remove the roof trusses from the deferred submittals, on cover sheet.
b) Remove all notes, information and details related to the roof trusses.
c) Remove typical details from sheet SN2 related to roof trusses, replace with applicable roof rafters
details.
Plans:
S6. Foundation plans, on sheets S-1.1,
Project No. 254003-01 B - 84 February 17, 2026
IDEFIEIRRED APPROVAJL rnEMS
PREFABRICATED ROOF TRUSSES .
. 2. IFIRE SPiRI K!LERS AND ALARMS
(.V BLOCKW,!:l.QAA~eJ:t!i~~~~ 4" O.C. B.N .. 6° O.C. E.N. & 12" O.C. F.N.
@ SH TRUSS WIE.N. TRUSS TO TRAN ER 180 PLF MIN. (U.N.O.)
@ TRUSS HANGER BY RUSS SU PLIER
® (1) SIMPSON HTS20 FLUSH BEAM TO DROP BEAM ( U.N.O.)
@ PROVIDE SOLID BLOCKING
0 DRA€~~§~~E}~~~€~9SFER 1700# FORCE MIN. (U.N 0.)
@ BLOCKEDOPENI~
@ g~~l~~~~~~;~~Et;~E~~~~ WALL AT ROOF LEVEL
® COUNTERSINK AS REQUIRED NO OVER CUT.
Construction of 21 Unit Condominiums City of Carlsbad– FIRST REVIEW
270 Juniper Ave City Permit No.: PC2025-0012
March 6, 2025 True North No.: 25-018-170
Page 10
a) Under the symbol legend,
i) Add the interior foundations.
ii) Add the slab on grade.
b) With the pad schedule, include the strip foundation information.
i) Make sure to differentiate between the exterior, interior and party wall footings.
c) Revise the Anchor bolts references on plans, to match the legend. Spacing is not referenced where
the anchor bolts are called out.
S7. Sheet SD1,
a) Detail 9,
i) Detail illustration shows 2 Top and bottom bars, yet note 1, specify only 1 T & B. Please
revise.
b) Detail 14,
i) Revise the column base, provide a moment resisting base.
S8. Architectural sections show dropped ceiling for the powder rooms at multiple buildings, please revise
framing plans and details to show said ceiling joists.
Project No. 254003-01 B - 85 February 17, 2026
IB= MAXIMUM SPACING
TOTAL MINIMUM NUMBER OF ANCHOR BOl TS EOUALL Y SPACED
AS POSSIBLE. SEE FOUNDATION SECTION NOTES ON SN1 SHEET(S)
FOR OTHER REQUIREMENTS. STRONG-TIE MASOZ/MASOPZ MUOS1Ll
ANCHORS CAN BE USED IN LIEU OF ANCHOR BOLTS, ON A ONE TO
ONE BASIS, WITH END DISTANCE OF 4" MIN .• AND MIN. SPACING@
1T 0 .C (PER ESR #2555). SEE DETAIL 11S01 FOR ILLUSTRATION.
1. ~T&BW/2'-0"MIN.LAP ~BEOMENT IN ADJACENT SLAB & FTG.
2. :;~f~11~~if. ~[Jel 1,s;. o.c.
TALL
1T MIN.
Construction of 21 Unit Condominiums City of Carlsbad– FIRST REVIEW
270 Juniper Ave City Permit No.: PC2025-0012
March 6, 2025 True North No.: 25-018-170
Page 11
S9. Roof and framing plans do not include information on the roof and floor diaphragm. Provide information
on the roof/floor diaphragm with referencing typical details, coordinate with lateral calculations.
S10. For roof framing plans, provide details for the California framing.
S11.
Structural Calculations:
S12. For lateral design for all buildings,
a) All in-plane shear calculations for all buildings utilize a redundancy factor of 1.0 instead of 1.3.
Please provide calculation justification that each building meets the exceptions specified in ASCE
7-16 Section 12.3.4.2.
b) Provide drag force check along gridline 2, Building B, especially for the 2nd and 3rd floor with the
cantilevered beams. Please show on plans adequate strapping.
c) Provide drag force check along gridlines A and C, Building D. Please show on plans adequate
strapping.
d) For all buildings, include the cantilevered column system in the lateral calculations.
Project No. 254003-01 B - 86 February 17, 2026
MAX SHEAR;283.41 x 40.501 (2 x 71.00); 80.83 PLF
USE: 15112· CDXRATED UNBLOCKED 32116 w@d COMMON NAILSAT6' 6" 12"0.C
CHORD FORCE• 263.41 x40.50 'I (8 x 71.00)• 818.43 LBS
DINING
SPLICE W MIN. 5 16d SINKER NAILS EACH SIDE OF SPLICE AT B" O.C. STANDARD CONSTRUCTIO
2-FLR DIAPHRAGM: V • 206.27 PLF ALIGN
MAX SHEAR• 206.27 x 40.50 I (2 x 71.00) • 58.83 PLF
USE: 23132" CDXRATED UNBLOCKED wl1()dCOMMON NAILSAT6" 6" 12"0 C.
CHORD FORCE• 206.27 x40.50 'I (8 x 71.00)• 595.65 LBS
SPLICE W, MIN. 5 16d SINKER NAILS EACH SIDE OF SPLICE AT B" O.C. STANDARD CONSTRUCTIO
1-FLR DIAPHRAGM: V • 206.16 PLF ALIGN
MAX SHEAR•208.16 x 21.001 (2 x 71.00) • 30.78 PLF
IJSE: 23132" CDX RA TED UNBLOCKED wl1()d COMMON NAILS AT 6" 6" 12" O C
CHORD FORGE• 208.16 x21.00 '/ (8 x 71.00)• 161 .62 LBS
SPLI E W, MIN. 5 16d SINKER NAIL EACH SIDE OF PUCE AT "O.C. STANDARD C NSTRUCT/
; MEMBERS,
Detail?
C.0 KEY NOTE NUMBER
0 CONTINUOUS 1 114" WIDE MIN. LVL I TIMBERSTRJ
CD ALIGN POST(S) WITH UPPER FLOOR POST(S), SE
(3) CONTINUOUS JOIST W/ E.N.
Construction of 21 Unit Condominiums City of Carlsbad– FIRST REVIEW
270 Juniper Ave City Permit No.: PC2025-0012
March 6, 2025 True North No.: 25-018-170
Page 12
i) Update the plans and details to provide a moment resisting column base.
e) As shear wall type 5 specify the use of 10d nail, nominal shear capacities shall be multiplied by
0.92 as per 2021 SDPWS Table 4.3A footnote 10. Revise shear wall calculations to update the
shear wall nominal capacities.
S13. Provide calculations for the stairs stringers.
S14. Provide calculations for beam 612, 3rd floor framing plan, along gridlines 1 and 4.
S15. Provide calculations for beam 412, 2nd floor framing plan for building B, along gridline 2. Show the
cantilevered section and the point load from beam 1.19.
Project No. 254003-01 B - 87 February 17, 2026
15132" APA 5 rnled 4) 2) Structural I
10 d's 10 d's
\41,~i1:Q. ...... @12"0.C.
HUCQ410 HUCQ410
Construction of 21 Unit Condominiums City of Carlsbad– FIRST REVIEW
270 Juniper Ave City Permit No.: PC2025-0012
March 6, 2025 True North No.: 25-018-170
Page 13
S16. Provide worst case post calculations.
a) Check for horizontal irregularities. As per ASCE 7-16 Table 12.3-2, Structural elements supporting
discontinuous walls that have vertical irregularity, shall be designed to resist the seismic load
effects, including an overstrength of Section 12.4.3.
S17. Retaining walls surrounding the lot. Retaining walls design themselves is under separate permit.
a) Please provide a check confirming that no surcharge will apply on any exterior footing for any of
the buildings.
If you have any questions regarding the above Non-Structural comments, please contact Mohammad Afaneh via
email mohammada@tncservices.com or telephone (562) 733-8030.
If you have any questions regarding the above Structural comments, please contact Mulham Hweidi via email
mulhamh@tncservices.com or telephone (562) 733-8030.
[END]
Project No. 254003-01 B - 88 February 17, 2026
APPENDIX C
Updated Onsite Infiltration Recommendations
Revised March 26, 2025
Project No. 254003-01 B - 89 February 17, 2026GEOTEK
GEOTECHNICAL | ENVIRONMENTAL | MATERIAL
June 7, 2024
Revised August 4, 2025
Project No. 3944-SD
Rincon Homes
5315 Avenida Encinas, Suite 200
Carlsbad, California 92008
Attention: Mr. Jonathan Franklin
Subject: Updated Onsite Infiltration Recommendations
Proposed Residential Development
270 Juniper Avenue
Carlsbad, California 92008
Reference: See Page 5
Dear Mr. Franklin:
GeoTek, Inc. (GeoTek) understands that the proposed BMPs associated with the development
of the subject site are planned to be:
• Permeable pavers
• Underground vault no. 1
• Raised filtration planters
• Offsite tree well
Underground vault no. 2 noted in GeoTek’s Onsite Infiltration Recommendations letter, dated
June 7, 2024, has been removed from the current set of plans and is no longer a planned BMP.
This letter is being submitted to provide updated design recommendations for the project’s
stormwater management. Recommendations regarding onsite management of stormwater
supersede those previously presented by GeoTek (2023 and 2024).
Project No. 254003-01 B - 91 February 17, 2026
GeoTek, Inc.
1384 Poinsettia Avenue, Suite A Vista, CA 92081-8505
(760) 599-0509 (760) 599-0593 www.geotekusa.com
Updated Onsite Infiltration Recommendations Revised August 4, 2025
270 Juniper Avenue Project No. 3944-SD
Carlsbad, California Page 2
PERCOLATION TESTING AND INFILTRATION ANALYSIS
GeoTek’s preliminary geotechnical evaluation report (GeoTek, 2023) advanced four percolation
borings, P-1, P-2, P-3, and P-4, tested to identify infiltration characteristics. In preparation for
this letter, GeoTek performed three additional percolation tests. On June 19, 2025, percolation
test borings P-5 and P-6 were advanced to evaluate the offsite tree well along Juniper Avenue.
On July 25, 2025, percolation test boring P-7 was advanced to evaluate the stormwater
management underground vault no. 1.
The test borings were prepared with a manual hand auger. The auger was 4-inches in diameter.
Approximately 2-inches of gravel was placed in the bottom of the test hole and a perforated PVC
conduit was inserted to prevent the sidewalls of the test boring to collapse. The boreholes were
allowed to presoak overnight, and testing was performed on the following day. Percolation
testing was performed by adding potable water to the borings, recording the initial depth to
water, allowing the water to percolate for 30 minutes, and the resultant depth to water was then
measured. In general, the percolation testing was performed for approximately 6 hours to allow
rates to stabilize. Depth to water was measured from top of the casing, where top of the casing
was higher than adjacent grade the height of the casing was recorded to adjust for the depth of
the boring.
For design of shallow infiltration basins, converting percolation rates to infiltration rates via the
Porchet method is generally acceptable and appropriate, as this method factors out the sidewall
component of the percolation results and represents the bottom conditions of a shallow basin
(infiltration). Therefore, the percolation data were converted to infiltration rates via the Porchet
method which is consistent with the guidelines of the City of Carlsbad.
A summary of the infiltration rates, boring depths, and boring locations including our previous
test holes are provided in the following table:
TABLE 1
FILED INFILTRATION TEST RESULTS
Test
No.
Approximate Boring Depth
(Inches)
Field Infiltration Results
(Inches per Hour)
P-1 24 2.34
P-2 24 2.31
P-3 49 1.57
P-4 59 4.25
P-5 42 1.10
P-6 35 1.38
P-7 91 0.84
Project No. 254003-01 B - 92 February 17, 2026GEOTEK
Updated Onsite Infiltration Recommendations Revised August 4, 2025
270 Juniper Avenue Project No. 3944-SD
Carlsbad, California Page 3
Copies of the percolation data sheets, and infiltration conversion sheets (Porchet Method) are
included in Appendix A.
UPDATED STORMWATER INFILTRATION RECOMMENDATIONS
The project is designed for four stormwater management conditions: Permeable pavers within
the vehicle pavement areas, underground vault no. 1, an offsite tree well along Juniper and raised
planters adjacent to the proposed buildings.
Permeable Pavers:
Four percolation tests (P-1, P-2, P-3, and P-4) were performed to evaluate stormwater infiltration
characteristics. Based on the proposed design and considering the slowest rate of the four
representative tests.
Based on City of Carlsbad mandatory consideration for infiltration of stormwater Appendix D,
Table D.1-1, the permeable pavers are within ten feet of proposed sewer lines and proposed
foundations of the buildings. Provided that the trench backfill for the proposed sewer laterals
and main line are compacted to 90% relative to ASTM D 1557 and above optimum moisture
content, adverse impacts to the sewer trench backfill are not anticipated. To reduce the potential
impact of infiltrating surface waters adjacent to the foundations an impermeable liner is
recommended to be constructed along the finish subgrade of the permeable pavers a lateral
distance of three feet. The liner should also be installed along the sidewall of the permeable
paver excavation up to one inch of finish grade or bottom of paver. If the project design
implements impermeable pavement between the building foundation and permeable pavement,
that meets the 3 feet lateral distance of impervious area, a lateral impermeable liner does not
need to be designed nor constructed, however, a deepened zero curb or cutoff curb is
recommended to reduced lateral migration of surface waters towards the building
foundations. The cutoff wall is recommended to be designed and constructed with the top the
same height of the paver and the bottom a minimum depth of the permeable pavement thickness.
Where permeable pavement encroaches within 3 feet of the distance to a building foundation,
but not closer than 2 feet, the deepened curb is recommended to be a thickness of 24 inches.
Underground Vault No. 1:
The proposed project has designed an underground infiltration vault system within the common
driveway between Unit 15 and 16. Percolation test P-7 was performed to evaluate stormwater
infiltration characteristics at the proposed stormwater vault. The test boring was proposed to
advanced to the invert depth, however, clean sands (sands with little to no silt and/or clay)
allowed the cuttings in the auger’s bucket to fallout and back into the test boring. The test boring
is considered to be representative of the material at the proposed invert of the vault. Although
Project No. 254003-01 B - 93 February 17, 2026GEOTEK
Updated Onsite Infiltration Recommendations Revised August 4, 2025
270 Juniper Avenue Project No. 3944-SD
Carlsbad, California Page 4
the vault is proposed beyond ten feet of proposed foundations and underground utilities, the
vault is recommended to be lined along the sides with an impermeable liner.
Raised Planters:
The proposed project has designed a raised planter BMP filtration system to manage stormwater
from the proposed rooftops. The design provides an outlet of the planters to the permeable
pavement section and ultimately the onsite underground detention vault. The BMP planters are
recommended to be fully lined along the bottom and sides with an impermeable liner.
Offsite Tree Well:
An offsite tree well BMP is proposed along Juniper Avenue, just east of the driveway apron in the
proposed concrete sidewalk. Two percolation tests (P-5, and P-6) were performed to evaluate
stormwater infiltration characteristics. The slowest rate of the two tests was utilized for the
design infiltration rate. Infiltration by means of tree wells is considered geotechnically suitable
provided potential lateral migration of groundwater is reduced by installation of impermeable
liners along the sidewalls.
TABLE 2
INFILTRATION RATE RECOMMENDATION
BMP Management
Device
Test
No.
Approximate
Boring Depth
(Inches)
Field
Infiltration
Results
Factor
of
Safety
Design
Infiltration Rate
(Inches/Hour)
Permeable Pavers P-3 49 1.57 3.0 0.52
Vault No. 1 P-7 91 0.84 2.0 0.42
Tree Well P-5 42 1.10 2.0 0.55
Project No. 254003-01 B - 94 February 17, 2026GEOTEK
Updated Onsite Infiltration Recommendations Revised August 4, 2025
270 Juniper Avenue Project No. 3944-SD
Carlsbad, California Page 5
Closure
Should you have any questions after reviewing this supplementary letter, please feel free to
contact our office at your convenience.
Respectfully submitted,
GeoTek, Inc.
Enclosure:
Figure 1 – Location Map
Figure 2 – Geotechnical Map
Appendix A – Percolation/Infiltration Worksheets
REFERENCES
City of Carlsbad, 2016, “City of Carlsbad BMP Design Manual,” Second Update to the February
16, 2016 Manual, Effective January 2, 2024.
GeoTek, Inc., In-house proprietary information.
Geotek, Inc. 2022, “Preliminary Geotechnical [Evaluation], Proposed Residential Development,
270 Juniper Avenue, Carlsbad, California,” Project No. 3944-SD, dated October 26, 2023.
Pasco, Laret, Suiter & Associates, 2025, “Improvement Plans For: Juniper Beach Homes, 270
Juniper Avenue,” undated (3 Sheets).
_____, 2025, “Grading Plans For: Juniper Coast Homes, 270 Juniper Avenue,” dated July 30
(10 Sheets).
Edward H. Lamont
CEG 1892, Exp. 07/31/26
Principal Geologist
Edwin R. Cunningham
RCE 81687, Exp. 03/31/26
Project Engineer
Project No. 254003-01 B - 95 February 17, 2026GEOTEK
Rincon Homes
270 Juniper Avenue
Carlsbad, California
APN: 204-240-22-00
Project No. 3944-SD
Figure 1
Site Location
Map
Site Location
Modified from USGS San
Luis Rey 2018 7.5-minute
Topographic Map Sheet
Project No. 254003-01 B - 96 February 17, 2026
1 0 .. 5 0
11000 500 0
1 0 . .5
'
SCALE 1 :24 000
KILOMETERS
METERS
0
MIILES
1 2
1000 2000
1
1000 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 110000 s:::::E;;::::is:======::::i;;;;;;;;;;;;;;;;;;;;;~E====:::::::1;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;i:::::::::::==:::::::~;;;;;;;;;;;;;;;;;;;~E====::::::i;;~;;;;;;;;;;;;;;;;;;3'.:::::::::===::SE;;;;;;;;;;;;;;;;;;;;31
FEET
GEOTEK
A16 T1
T1
T1
T1
Kg
r
No
r
t
h
Scale: 1”=40’
Approximate
Note: Base map provided by Client.
A’
Recent Fill over
Paralic Deposits Recent Fill over
Paralic Deposits
Recent Fill over
Paralic Deposits
LCB-2Colluvium
Creep
Santiago
Fm
Santiago
Fm
B1 B2
TD 30
TD 55
?????
Rincon Homes
270 Juniper Avenue
Carlsbad, California
APN: 204-240-22-00
Project No. 3944-SD
Figure 2
Geotechnical
Map
LEGEND
(Locations are Approximate)
Manual Auger
Boring Location
Percolation Test
LocationP-7
HA-1
Old Paralic DepositsQop6-7
HA-1
HA-2
P-1
P-2
Qop6-7
Qop6-7
Approximate Limits of Study
P-4 P-3
P-7
P-5
P-6
Project No. 254003-01 B - 97 February 17, 2026
I I
,r.mr,: 12
FF •$,l,,9
PA0=5U
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UNIT 13
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llHlf fO
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PAD~.s,,·,2 I
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IJ/o/IT7 ff~su
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PRIVA.TE FIRE SERVICE NOTE:
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GEOTEK
APPENDIX A
PERCOLATION / INFILTRATION WORKSHEETS
Project No. 254003-01 B - 98 February 17, 2026GEOTEK
Job No.: 3944-SD .
Date: 8/25/23 .
After Test: 24" .
Reading
No.Time
Time
Interval
(Min)
Total
Depth of
Hole
(Inches)
Initial
Water
Level
(Inches)
Final
Water
Level
(Inches)
∆ In Water
Level
(Inches)
Comments
1 12:18 30 24 0 17 0
2 12:50 30 24 4.5 21.5 17
3 13:25 30 24 3.5 21 17.5
4 14:05 30 24 4 22 18
5 14:40 30 24 3.75 21.5 17.75
6 15:15 30 24 2 22 20
7 15:45 30 24 1 21 20
8 16:20 30 24 1.5 20 18.5
9 16:55 30 24 1.25 22.5 21.25
10 17:25 30 24 2.75 21 18.25
11 17:55 30 24 1.5 20 18.5
12 18:35 30 24 2 19 17
PERCOLATION DATA SHEET
Project: 270 Juniper ,
Test Hole No.: P-1 Tested By: EM ,
Depth of Hole As Drilled: 24" Before Test: __24"______________________
Project No. 254003-01 B - 99 February 17, 2026
Equation -It =
Havg = (HO+HF)/2 =
It = Inches per Hour
Time Interval, Δt = 30
Client:
Project:
Project No:3944-SD
Date:8/25/2023
Boring No.P-1
Rincon Homes
270 Juniper
Final Depth to Water, DF =19.00
Test Hole Radius, r =2.00
Initial Depth to Water, DO =2
2.34
Total Test Hole Depth, DT = 24
ΔH (60r)
Δt (r+2Havg)
HO = DT - DO = 22.00
HF = DT - DF = 5.00
ΔH = ΔD = HO- HF = 17.00
13.50
Field Infiltration Rate (Porchet Method)
Project No. 254003-01 B - 100 February 17, 2026
GEOTEK
Job No.: 3944-SD .
Date: 8/25/23 .
After Test: 24" .
Reading
No.Time
Time
Interval
(Min)
Total
Depth of
Hole
(Inches)
Initial
Water
Level
(Inches)
Final
Water
Level
(Inches)
∆ In Water
Level
(Inches)
Comments
1 12:18 30 24 1 23 0
2 12:50 30 24 6.5 18.5 12
3 13:25 30 24 7 20 13
4 14:05 30 24 4.5 21 16.5
5 14:40 30 24 4 19.5 15.5
6 15:15 30 24 3 19 16
7 15:45 30 24 3 19 16
8 16:20 30 24 3 17.5 14.5
9 16:55 30 24 2.5 18.5 16
10 17:25 30 24 4.75 17 12.25
11 17:55 30 24 2.5 18 15.5
12 18:35 30 24 4.5 19.5 15
PERCOLATION DATA SHEET
Project: 270 Juniper ,
Test Hole No.: P-2 Tested By: EM ,
Depth of Hole As Drilled: 24" Before Test: __24"______________________
Project No. 254003-01 B - 101 February 17, 2026
Equation -It =
Havg = (HO+HF)/2 =
It = Inches per Hour
Time Interval, Δt = 30
Client:
Project:
Project No:
Date:
Boring No.
3944-SD
8/25/2023
P-2
Rincon Homes
270 Juniper
Final Depth to Water, DF =19.50
Test Hole Radius, r =2.00
Initial Depth to Water, DO =4.5
2.31
Total Test Hole Depth, DT = 24
ΔH (60r)
Δt (r+2Havg)
HO = DT - DO = 19.50
HF = DT - DF = 4.50
ΔH = ΔD = HO- HF = 15.00
12.00
Field Infiltration Rate (Porchet Method)
Project No. 254003-01 B - 102 February 17, 2026
GEOTEK
Job No.: 3944-SD .
Date: 5/08/24 .
After Test: 49" .
Reading
No.Time
Time
Interval
(Min)
Total
Depth of
Hole
(Inches)
Initial
Water
Level
(Inches)
Final
Water
Level
(Inches)
∆ In Water
Level
(Inches)
Comments
1 10:25 30 49 17.75 59.2 0
2 10:55 30 49 13.7 37 23.3
3 11:25 10 49 14 27 13
4 11:35 10 49 15 22.5 7.5
5 11:45 10 49 12 24.2 12.2
6 11:55 10 49 12 25 13
7 12:05 10 49 12 21.4 9.4
8 12:15 10 49 18.8 26 7.2
PERCOLATION DATA SHEET
Project: 270 Juniper ,
Test Hole No.: P-3 Tested By: TM ,
Depth of Hole As Drilled: 49" Before Test: __49"______________________
Project No. 254003-01 B - 103 February 17, 2026
Equation -It =
Havg = (HO+HF)/2 =
It = Inches per Hour1.57
Total Test Hole Depth, DT = 49
ΔH (60r)
Δt (r+2Havg)
HO = DT - DO = 30.20
HF = DT - DF = 23.00
ΔH = ΔD = HO- HF = 7.20
26.60
Final Depth to Water, DF =26.00
Test Hole Radius, r =2.00
Initial Depth to Water, DO =18.8
Time Interval, Δt = 10
Client:Rincon Homes
Project:270 Juniper
Project No:3944-SD
Date:5/8/2024
Boring No.P-3
Field Infiltration Rate (Porchet Method)
Project No. 254003-01 B - 104 February 17, 2026
GEOTEK
Job No.: 3944-SD .
Date: 5/08/24 .
After Test: 59" .
Reading
No.Time
Time
Interval
(Min)
Total
Depth of
Hole
(Inches)
Initial
Water
Level
(Inches)
Final
Water
Level
(Inches)
∆ In Water
Level
(Inches)
Comments
1 10:35 30 59 14.25 44 29.75
2 11:05 30 59 16.9 45 28.1
3 11:35 30 59 14.2 41 26.8
4 12:05 30 59 15.8 42.8 27
5 12:35 30 59 15.3 36 20.7
6 2:32 10 59 12 32.5 20.5
7 2:42 10 59 12 35.8 23.8
8 2:52 10 59 14.4 33.7 19.3
9 3:02 10 59 15.2 33 17.8
10 3:12 10 59 16 39 23
PERCOLATION DATA SHEET
Project: 270 Juniper ,
Test Hole No.: P-4 Tested By: TM ,
Depth of Hole As Drilled: 59" Before Test: __59"______________________
Project No. 254003-01 B - 105 February 17, 2026
Equation -It =
Havg = (HO+HF)/2 =
It = Inches per Hour4.25
Total Test Hole Depth, DT = 59
ΔH (60r)
Δt (r+2Havg)
HO = DT - DO = 43.00
HF = DT - DF = 20.00
ΔH = ΔD = HO- HF = 23.00
31.50
Final Depth to Water, DF =39.00
Test Hole Radius, r =2.00
Initial Depth to Water, DO =16
Time Interval, Δt = 10
Client:Rincon Homes
Project:270 Juniper
Project No:3944-SD
Date:5/8/2024
Boring No.P-4
Field Infiltration Rate (Porchet Method)
Project No. 254003-01 B - 106 February 17, 2026
GEOTEK
Job No.: 3944-SD .
Date: 6/20/25 .
After Test: 42'' .
Reading
No.Time
Time
Interval
(Min)
Total
Depth of
Hole
(Inches)
Initial
Water
Level
(Inches)
Final
Water
Level
(Inches)
∆ In Water
Level
(Inches)
Comments
1 8:30 30 42 0 23.0 23
All depths measured from top of
casing
2 9:30 30 42 0 27.5 27.5
3 10:00 30 42 0 21.5 21.5
4 11:11 19 42 0 19.5 19.5
5 11:41 30 42 0 21.0 21
6 12:10 30 42 0 19.0 19
7 12:40 30 42 0 19.0 19
8 1:10 30 42 0 19.5 19.5
9 1:40 30 42 0 19.5 19.5
10 2:10 30 42 0 18.5 18.5
PERCOLATION DATA SHEET
Project: 270 Juniper
Test Hole No.: P-5 Tested By: SS ,
Depth of Hole As Drilled: 42" Before Test: __42"______________________
Project No. 254003-01 B - 107 February 17, 2026
Equation -It =
Havg = (HO+HF)/2 =
It = Inches per Hour
See Table D.2-1 For Design Rate
ΔH = ΔD = HO- HF = 18.50
32.75
1.10
Rincon Homes
270 Juniper
ΔH (60r)
Δt (r+2Havg)
HO = DT - DO = 42.00
HF = DT - DF = 23.50
Test Hole Radius, r =2.00
Initial Depth to Water, DO =0
Total Test Hole Depth, DT = 42.00
Boring No.P-5
Field Infiltration Rate (Porchet Method)
Time Interval, Δt = 30
Final Depth to Water, DF =18.50
Client:
Project:
Project No:3944-SD
Date:6/20/2025
Project No. 254003-01 B - 108 February 17, 2026
GEOTEK
Job No.: 3944-SD .
Date: 6/20/25 .
After Test: 35'' .
Reading
No.Time
Time
Interval
(Min)
Total
Depth of
Hole
(Inches)
Initial
Water
Level
(Inches)
Final
Water
Level
(Inches)
∆ In Water
Level
(Inches)
Comments
1 8:30 30 35 0 26 26
All depths measured from top of
casing
2 9:30 30 35 0 23.5 23.5
3 10:40 30 35 0 21.5 21.5
4 11:10 30 35 0 21 21
5 11:40 30 35 0 20.25 20.25
6 12:10 30 35 0 18.5 18.5
7 12:40 30 35 0 18.25 18.25
8 1:10 30 35 0 19.5 19.5
9 1:40 30 35 0 19 19
10 2:10 30 35 0 18.5 18.5
PERCOLATION DATA SHEET
Project: 270 Juniper
Test Hole No.: P-6 Tested By: SS ,
Depth of Hole As Drilled: 35" Before Test: __35"______________________
Project No. 254003-01 B - 109 February 17, 2026
Equation -It =
Havg = (HO+HF)/2 =
It = Inches per Hour
See Table D.2-1 For Design Rate
ΔH = ΔD = HO- HF = 18.50
25.75
1.38
Rincon Homes
270 Juniper
ΔH (60r)
Δt (r+2Havg)
HO = DT - DO = 35.00
HF = DT - DF = 16.50
Test Hole Radius, r =2.00
Initial Depth to Water, DO =0
Total Test Hole Depth, DT = 35.00
Boring No.P-6
Field Infiltration Rate (Porchet Method)
Time Interval, Δt = 30
Final Depth to Water, DF =18.50
Client:
Project:
Project No:3944-SD
Date:6/20/2025
Project No. 254003-01 B - 110 February 17, 2026
GEOTEK
Job No.: 3944-SD .
Date: 7/26/2025
After Test: 95'' .
Reading
No.Time
Time
Interval
(Min)
Total
Depth of
Hole
(Inches)
Initial
Water
Level
(Inches)
Final
Water
Level
(Inches)
∆ In Water
Level
(Inches)
Comments
1 8:32 30 97 8.75 96 87.25
All depths measured from top of
casing
2 9:03 30 96 9 77.5 68.5 Casing is 6 inches above ground
3 9:34 30 96 9.5 78.5 69
4 10:04 30 96 9.25 76.25 67
5 10:34 30 96 9 73.5 64.5
6 11:05 30 96 9.25 73 63.75
7 11:35 30 95 9.25 68.25 59
8 12:05 30 95 9 64.25 55.25
9 12:35 30 95 8.5 57.25 48.75
10 1:05 30 95 9 53.25 44.25
11 1:36 30 95 9 47.5 38.5
12 2:07 30 95 8.75 44 35.25
13 2:37 30 95 8.5 42.75 34.25
14 3:07 30 95 9 39.75 30.75
PERCOLATION DATA SHEET
Project: 270 Juniper
Test Hole No.: P-7 Tested By: BJ ,
Depth of Hole As Drilled: 97" Before Test: __97"______________________
Project No. 254003-01 B - 111 February 17, 2026
Equation -It =
Havg = (HO+HF)/2 =
It = Inches per Hour
See Table D.2-1 For Design Rate
Time Interval, Δt = 30
Client: Rincon Homes
Project: 270 Juniper
Project No: 3944-SD
Date: 6/20/2025
Boring No. P-7
Field Infiltration Rate (Porchet Method)
Final Depth to Water, DF =33.75
Test Hole Radius, r =2.00
Initial Depth to Water, DO =3
0.84
Total Test Hole Depth, DT = 91.00
ΔH (60r)
Δt (r+2Havg)
HO = DT - DO = 88.00
HF = DT - DF = 57.25
ΔH = ΔD = HO- HF = 30.75
72.63
Project No. 254003-01 B - 112 February 17, 2026
GEOTEK
Permeable Pavers
D-1
Sept. 2021
Restriction Element
Is Element
Applicable?
(Yes/No)
BMP is within 100’ of Contaminated Soils No
BMP is within 100’ of Industrial Activities Lacking Source Control No
BMP is within 100’ of Well/Groundwater Basin No
BMP is within 50’ of Septic Tanks/Leach Fields No
BMP is within 10’ of Structures/Tanks/Walls Yes*
BMP is within 10’ of Sewer Utilities Yes*
BMP is within 10’ of Groundwater Table No
BMP is within Hydric Soils No
BMP is within Highly Liquefiable Soils and has Connectivity to Structures No
BMP is within 1.5 Times the Height of Adjacent Steep Slopes (≥25%) No
County Staff has Assigned “Restricted” Infiltration Category No
BMP is within Predominantly Type D Soil N/A
BMP is within 10’ of Property Line N/A
Optional BMP is within Fill Depths of ≥5’ (Existing or Proposed) N/A
Considerations BMP is within 10’ of Underground Utilities N/A
BMP is within 250’ of Ephemeral Stream N/A
Other (Provide detailed geotechnical support) N/A
Result
Based on examination of the best available information,
I have not identified any restrictions above.
Unrestricted
Based on examination of the best available information,
I have identified one or more restrictions above.
Restricted
Analysis
Analysis of Infiltration Restrictions
This section is only applicable if the analysis of infiltration restrictions is performed by a
licensed engineer practicing in geotechnical engineering. The SWQMP Preparer and
Geotechnical Engineer must work collaboratively to identify any infiltration restrictions identified in
Table D.1-1 below. Upon completion of this section, the Geotechnical Engineer must characterize
each DMA as Restricted or Unrestricted for infiltration and provide adequate support/discussion in
the geotechnical report. A DMA is considered restricted when one or more restrictions exist which
cannot be reasonably resolved through site design changes.
Table D.1-1: Considerations for Geotechnical Analysis of Infiltration Restrictions
Mandatory
Considerations
*See GeoTek “updated Onsite Infiltration Evaluation, PN 3944-SD, dated August 4, 2025”
Project No. 254003-01 B - 113 February 17, 2026
D.1
Permeable Pavers
D-1
Sept. 2021
Table D.1-1 is divided into Mandatory Considerations and Optional Considerations. Mandatory
considerations include elements that may pose a significant risk to human health and safety and must
always be evaluated. Optional Considerations include elements that are not necessarily associated with
human health and safety, so analysis is not mandated through this guidance document. All elements
presented in this table are subject to the discretion of the Geotechnical Engineer if adequate supporting
information is provided.
Applicants must evaluate infiltration restrictions through use of the best available data. A list of
resources available for evaluation is provided in Section B.2
Determination of Design Infiltration Rates
This section is only applicable if the determination of design infiltration rates is performed
by a licensed engineer practicing in geotechnical engineering. The guidance in this section
identifies methods for identifying observed infiltration rates, corrected infiltration rates, safety factors,
and design infiltration rates for use in structural BMP design. Upon completion of this section, the
Geotechnical Engineer must recommend a design infiltration rate for each DMA and provide adequate
support/discussion in the geotechnical report.
Table D.2-1: Elements for Determination of Design Infiltration Rates
Item
Value
Unit
Initial Infiltration Rate
Identify per Section D.2.1
1.57
in/hr
Corrected Infiltration Rate
Identify per Section D.2.2
1.57
in/hr
Safety Factor
Identify per Section D.2.3
3.00
unitless
Design Infiltration Rate
Corrected Infiltration Rate ÷ Safety Factor
0.52
in/hr
*See GeoTek “updated Onsite Infiltration Evaluation, PN 3944-SD, dated August 4, 2025”
Project No. 254003-01 B - 114 February 17, 2026
2
D-12
Sept. 2021
Permeable Pavers
Table D.2-3: Determination of Safety Factor
Consideration Assigned
Weight (w)
Factor
Value (v)
Product (p)
p = w x v
Infiltration Testing Method 0.25 Refer to 0.50
Suitability Soil Texture Class 0.25 Table D.2-4 0.25
Assessment Soil Variability 0.25 0.75
(A) Depth to Groundwater/Obstruction 0.25 0.50
Suitability Assessment Safety Factor, SA = p 1.50
Pretreatment 0.50 Refer to 0.50
Resiliency 0.25 Table D.2-4 0.25 Design
(B) Compaction 0.25 0.75
Design Safety Factor, SB = p 1.50
Safety Factor, S = SA x SB 3.00
(Must be always greater than or equal to 2)
The geotechnical engineer should reference Table D.2-4 below in order to determine appropriate
factor values for use in the table above. The values in the table below are subjective in nature and
the geotechnical engineer may use professional discretion in how the points are assigned.
*See GeoTek “updated Onsite Infiltration Evaluation, PN 3944-SD, dated August 4, 2025”
Project No. 254003-01 B - 115 February 17, 2026
Underground Vault V1
D-1
Sept. 2021
Restriction Element
Is Element
Applicable?
(Yes/No)
BMP is within 100’ of Contaminated Soils No
BMP is within 100’ of Industrial Activities Lacking Source Control No
BMP is within 100’ of Well/Groundwater Basin No
BMP is within 50’ of Septic Tanks/Leach Fields No
BMP is within 10’ of Structures/Tanks/Walls Yes*
BMP is within 10’ of Sewer Utilities Yes*
BMP is within 10’ of Groundwater Table No
BMP is within Hydric Soils No
BMP is within Highly Liquefiable Soils and has Connectivity to Structures No
BMP is within 1.5 Times the Height of Adjacent Steep Slopes (≥25%) No
County Staff has Assigned “Restricted” Infiltration Category No
BMP is within Predominantly Type D Soil N/A
BMP is within 10’ of Property Line N/A
Optional BMP is within Fill Depths of ≥5’ (Existing or Proposed) N/A
Considerations BMP is within 10’ of Underground Utilities N/A
BMP is within 250’ of Ephemeral Stream N/A
Other (Provide detailed geotechnical support) N/A
Result
Based on examination of the best available information,
I have not identified any restrictions above.
Unrestricted
Based on examination of the best available information,
I have identified one or more restrictions above.
Restricted
Analysis
Analysis of Infiltration Restrictions
This section is only applicable if the analysis of infiltration restrictions is performed by a
licensed engineer practicing in geotechnical engineering. The SWQMP Preparer and
Geotechnical Engineer must work collaboratively to identify any infiltration restrictions identified in
Table D.1-1 below. Upon completion of this section, the Geotechnical Engineer must characterize
each DMA as Restricted or Unrestricted for infiltration and provide adequate support/discussion in
the geotechnical report. A DMA is considered restricted when one or more restrictions exist which
cannot be reasonably resolved through site design changes.
Table D.1-1: Considerations for Geotechnical Analysis of Infiltration Restrictions
Mandatory
Considerations
*See GeoTek “Updated Onsite Infiltration Evaluation” PN 3944-SD dated August 4, 2025
Project No. 254003-01 B - 116 February 17, 2026
D.1
Underground Vault
D-1
Sept. 2021
Table D.1-1 is divided into Mandatory Considerations and Optional Considerations. Mandatory
considerations include elements that may pose a significant risk to human health and safety and must
always be evaluated. Optional Considerations include elements that are not necessarily associated with
human health and safety, so analysis is not mandated through this guidance document. All elements
presented in this table are subject to the discretion of the Geotechnical Engineer if adequate supporting
information is provided.
Applicants must evaluate infiltration restrictions through use of the best available data. A list of
resources available for evaluation is provided in Section B.2
Determination of Design Infiltration Rates
This section is only applicable if the determination of design infiltration rates is performed
by a licensed engineer practicing in geotechnical engineering. The guidance in this section
identifies methods for identifying observed infiltration rates, corrected infiltration rates, safety factors,
and design infiltration rates for use in structural BMP design. Upon completion of this section, the
Geotechnical Engineer must recommend a design infiltration rate for each DMA and provide adequate
support/discussion in the geotechnical report.
Table D.2-1: Elements for Determination of Design Infiltration Rates
Item
Value
Unit
Initial Infiltration Rate
Identify per Section D.2.1
0.84
in/hr
Corrected Infiltration Rate
Identify per Section D.2.2
0.84
in/hr
Safety Factor
Identify per Section D.2.3
2.0
unitless
Design Infiltration Rate
Corrected Infiltration Rate ÷ Safety Factor
0.42
in/hr
See GeoTek “Updated Onsite Infiltration Evaluation” PN 3944-SD dated August 4, 2025
Project No. 254003-01 B - 117 February 17, 2026
D-12
Sept. 2021
Underground Vault
Table D.2-3: Determination of Safety Factor
Consideration Assigned
Weight (w)
Factor
Value (v)
Product (p)
p = w x v
Infiltration Testing Method 0.25 Refer to 0.50
Suitability Soil Texture Class 0.25 Table D.2-4 0.25
Assessment Soil Variability 0.25 0.25
(A) Depth to Groundwater/Obstruction 0.25 0.50
Suitability Assessment Safety Factor, SA = p 1.50
Pretreatment 0.50 Refer to 0.50
Resiliency 0.25 Table D.2-4 0.25 Design
(B) Compaction 0.25 0.25
Design Safety Factor, SB = p 1.0
Safety Factor, S = SA x SB 2.0
(Must be always greater than or equal to 2)
The geotechnical engineer should reference Table D.2-4 below in order to determine appropriate
factor values for use in the table above. The values in the table below are subjective in nature and
the geotechnical engineer may use professional discretion in how the points are assigned.
See GeoTek “Updated Onsite Infiltration Evaluation” PN 3944-SD dated August 4, 2025
Project No. 254003-01 B - 118 February 17, 2026
D-12
Sept. 2021
Restriction Element
Is Element
Applicable?
(Yes/No)
BMP is within 100’ of Contaminated Soils No
BMP is within 100’ of Industrial Activities Lacking Source Control No
BMP is within 100’ of Well/Groundwater Basin No
BMP is within 50’ of Septic Tanks/Leach Fields No
BMP is within 10’ of Structures/Tanks/Walls Yes*
BMP is within 10’ of Sewer Utilities Yes*
BMP is within 10’ of Groundwater Table No
BMP is within Hydric Soils No
BMP is within Highly Liquefiable Soils and has Connectivity to Structures No
BMP is within 1.5 Times the Height of Adjacent Steep Slopes (≥25%) No
County Staff has Assigned “Restricted” Infiltration Category No
BMP is within Predominantly Type D Soil N/A
BMP is within 10’ of Property Line N/A
Optional BMP is within Fill Depths of ≥5’ (Existing or Proposed) N/A
Considerations BMP is within 10’ of Underground Utilities N/A
BMP is within 250’ of Ephemeral Stream N/A
Other (Provide detailed geotechnical support) N/A
Result
Based on examination of the best available information,
I have not identified any restrictions above.
Unrestricted
Based on examination of the best available information,
I have identified one or more restrictions above.
Restricted
Analysis
Analysis of Infiltration Restrictions
This section is only applicable if the analysis of infiltration restrictions is performed by a
licensed engineer practicing in geotechnical engineering. The SWQMP Preparer and
Geotechnical Engineer must work collaboratively to identify any infiltration restrictions identified in
Table D.1-1 below. Upon completion of this section, the Geotechnical Engineer must characterize
each DMA as Restricted or Unrestricted for infiltration and provide adequate support/discussion in
the geotechnical report. A DMA is considered restricted when one or more restrictions exist which
cannot be reasonably resolved through site design changes.
Table D.1-1: Considerations for Geotechnical Analysis of Infiltration Restrictions
Mandatory
Considerations
*See GeoTek “updated Onsite Infiltration Evaluation, PN 3944-SD, dated August 4, 2025”
Raised Planters
Project No. 254003-01 B - 119 February 17, 2026
D1
Tree Well
D-1
Sept. 2021
Restriction Element
Is Element
Applicable?
(Yes/No)
BMP is within 100’ of Contaminated Soils No
BMP is within 100’ of Industrial Activities Lacking Source Control No
BMP is within 100’ of Well/Groundwater Basin No
BMP is within 50’ of Septic Tanks/Leach Fields No
BMP is within 10’ of Structures/Tanks/Walls Yes*
BMP is within 10’ of Sewer Utilities Yes*
BMP is within 10’ of Groundwater Table No
BMP is within Hydric Soils No
BMP is within Highly Liquefiable Soils and has Connectivity to Structures No
BMP is within 1.5 Times the Height of Adjacent Steep Slopes (≥25%) No
County Staff has Assigned “Restricted” Infiltration Category No
BMP is within Predominantly Type D Soil N/A
BMP is within 10’ of Property Line N/A
Optional BMP is within Fill Depths of ≥5’ (Existing or Proposed) N/A
Considerations BMP is within 10’ of Underground Utilities N/A
BMP is within 250’ of Ephemeral Stream N/A
Other (Provide detailed geotechnical support) N/A
Result
Based on examination of the best available information,
I have not identified any restrictions above.
Unrestricted
Based on examination of the best available information,
I have identified one or more restrictions above.
Restricted
Analysis
Analysis of Infiltration Restrictions
This section is only applicable if the analysis of infiltration restrictions is performed by a
licensed engineer practicing in geotechnical engineering. The SWQMP Preparer and
Geotechnical Engineer must work collaboratively to identify any infiltration restrictions identified in
Table D.1-1 below. Upon completion of this section, the Geotechnical Engineer must characterize
each DMA as Restricted or Unrestricted for infiltration and provide adequate support/discussion in
the geotechnical report. A DMA is considered restricted when one or more restrictions exist which
cannot be reasonably resolved through site design changes.
Table D.1-1: Considerations for Geotechnical Analysis of Infiltration Restrictions
Mandatory
Considerations
*See GeoTek “Updated Onsite Infiltration Evaluation, PN 3944-SD dated August 4, 2025”
Project No. 254003-01 B - 120 February 17, 2026
D.1
Tree Well
D-1
Sept. 2021
Table D.1-1 is divided into Mandatory Considerations and Optional Considerations. Mandatory
considerations include elements that may pose a significant risk to human health and safety and must
always be evaluated. Optional Considerations include elements that are not necessarily associated with
human health and safety, so analysis is not mandated through this guidance document. All elements
presented in this table are subject to the discretion of the Geotechnical Engineer if adequate supporting
information is provided.
Applicants must evaluate infiltration restrictions through use of the best available data. A list of
resources available for evaluation is provided in Section B.2
Determination of Design Infiltration Rates
This section is only applicable if the determination of design infiltration rates is performed
by a licensed engineer practicing in geotechnical engineering. The guidance in this section
identifies methods for identifying observed infiltration rates, corrected infiltration rates, safety factors,
and design infiltration rates for use in structural BMP design. Upon completion of this section, the
Geotechnical Engineer must recommend a design infiltration rate for each DMA and provide adequate
support/discussion in the geotechnical report.
Table D.2-1: Elements for Determination of Design Infiltration Rates
Item
Value
Unit
Initial Infiltration Rate
Identify per Section D.2.1
0.84
in/hr
Corrected Infiltration Rate
Identify per Section D.2.2
0.84
in/hr
Safety Factor
Identify per Section D.2.3
2.0
unitless
Design Infiltration Rate
Corrected Infiltration Rate ÷ Safety Factor
0.42
in/hr
See GeoTek “Updated Onsite Infiltration Evaluation, PN 3944-SD dated August 4, 2025”
Project No. 254003-01 B - 121 February 17, 2026
2
D-12
Sept. 2021
Tree Well
Table D.2-3: Determination of Safety Factor
Consideration Assigned
Weight (w)
Factor
Value (v)
Product (p)
p = w x v
Infiltration Testing Method 0.25 Refer to 0.50
Suitability Soil Texture Class 0.25 Table D.2-4 0.25
Assessment Soil Variability 0.25 0.25
(A) Depth to Groundwater/Obstruction 0.25 0.50
Suitability Assessment Safety Factor, SA = p 1.50
Pretreatment 0.50 Refer to 0.50
Resiliency 0.25 Table D.2-4 0.25 Design
(B) Compaction 0.25 0.25
Design Safety Factor, SB = p 1.0
Safety Factor, S = SA x SB 2.0
(Must be always greater than or equal to 2)
The geotechnical engineer should reference Table D.2-4 below in order to determine appropriate
factor values for use in the table above. The values in the table below are subjective in nature and
the geotechnical engineer may use professional discretion in how the points are assigned.
See GeoTek “Updated Onsite Infiltration Evaluation, PN 3944-SD dated August 4, 2025”
Project No. 254003-01 B - 122 February 17, 2026