HomeMy WebLinkAboutCDP 2016-0006; MDI-1 - 4 UNIT APARTMENT COMPLEX - JEFFERSON STREET; FINAL SOILS REPORT; 2021-04-28Project No. FC-18-11-154
February 25, 2019
Mr. Jose Luis Arellano
835 Ladybug Lane
San Marcos, CA 92069
§M§ GEOTECHNICAL SOLUTIONS, INC.
Consulting Geotechnical Engineers & Geologists
5931 Sea Lion Place, Suite 109
Carlsbad, California 92010
Office: 7 60-602-7815
smsgeosol.inc@gmail.com
Report of Geotechnical Engineering Observations And Compaction Testing, Remedial Pad
Grading, Proposed Arellano 4-Unit Apartments, 2637 Jefferson Street, Carlsbad, California
(Project No. CDP 2016-006, Drawing No. 509-4A)
Submitted herewith please find the following summary report of our geotechnical engineering
observations and compaction testing completed by our firm in connection with the remedial building
pad grading at the above-referenced property. Approximate limits of the compacted fill areas at the
property are delineated on the enclosed Approximate Compaction Tests Location Map (Figure 1 ),
reproduced from the project Precise Grading Plan (Sheet 3 of 5).
Overall, remedial grading operations at the project site chiefly consisted of preexisting pool
demolition and backfill works, wall backfill compaction, and remedial building pad grading and
reestablishing final design grades. Earthworks and remedial building pad grading operations within
the designated limits were performed under engineering observations and compaction testing
services provided by this office from November 16, 2018 through February 20, 2019.
I. REFERENCES
The following pertinent reports and documents were used as a basis of our engineering observations
and compaction testing services.
1. "Precise Grading Plan for MFD-01 ( 4-Units Apartment Complex)," (Sheet 3 of 5), Prepared
by Victor Rodriguez-Fernandez.
2. "Geotechnical Update, Proposed Arellano 4-Unit Apartments, 2637 Jefferson Street,
Carlsbad, California," Prepared by SMS Geotechnical Solutions, Inc., dated March 15,
2018.
Report of Geotechnical Engineering Observations And Compaction February 25, 2019
Testing, Remedial Pad Grading, 2637 Jefferson Street, Carlsbad, California Page 2
3. "Geotechnical Plan Review, Proposed Arellano 4-Unit Apartments, 2637 Jefferson Street,
Carlsbad, California," SMS Geotechnical Solutions, Inc., dated May 8, 2017.
4. "Revised PICP Construction Procedure Alternative, Proposed Arellano 4-Unit Apartments,
2637 Jefferson Street, Carlsbad," SMSGeotechnical Solutions, Inc., dated April 10, 2017.
5. "Alternative PICP Construction Procedure, Proposed Arellano 4-Unit Apartments, 2637
Jefferson Street, Carlsbad, California," SMSGeotechnical Solutions, Inc., dated February
14, 2017.
6. "Geotechnical Plan Review Update, Proposed Arellano 4-unit Apartments, 2637 Jefferson
Street, Carlsbad, California," SMSGeotechnical Solutions, Inc., dated October 24, 2016.
7. "Geotechnical Investigation, Proposed 3-story 4-Unit Residence, 2637 Jefferson Street,
Carlsbad, California," SMSGeotechnical Solutions, Inc., dated January 11, 2016.
II. GEOTECHNICAL CONDITIONS
Geotechnical conditions at the project site were found to be substantially the same as described in
the referenced Geotechnical Investigation report (Referenced 7). In general, pre-remedial grading
conditions consisted of an existing older development which supported a single-story residence with
the associated structures and improvements including a rear yard swimming pool. The pre-existing
building was demolished and the swimming pool backfilled as part of the project redevelopment.
An existing approximately 5 feet high CMU retaining wall which marked the western property line
continues to remain and a new retaining wall was constructed behind the existing wall along the
majority if the property line, as shown on the project plans.
The project property was generally underlain by a section ofloose and compressible undifferentiated
fill/topsoil deposits mantle, on the order of2.5 feet thick, over dense to very dense silty sandstone
Terrace Deposits.
III. LABO RA TORY TESTING
Pertaining maximum dry densities and optimum moisture contents (ASTM D1557) for the onsite
representative soil types were obtained from the project Geotechnical Investigation report, dated
January 11, 2016 (Reference 7), and performing additional testing on the manufactured fill mixture
and import soils. Pertinent test results are summarized on the attached Maximum Dry Density &
Optimum Moisture Content sheet, Figure 2.
Report of Geotechnical Engineering Observations And Compaction February 25, 2019
Testing, Remedial Pad Grading, 2637 Jefferson Street, Carlsbad, California Page 3
IV. GROUND PREPARATION AND GRADING OPERA TIO NS
Prior to the remedial grading operations, any surface vegetation, roots and tree stumps, old
foundation, pool shell, surface improvements and buried structures were removed and cleared for
the project areas, as appropriate. Upper surficial loose and compressible undifferentiated fill/topsoil
deposits mantle within the Approximate Limits of Grading areas (see attached Approximate
Compaction Tests Location Map, Figure 1) encompassing the building envelope plus a minimum
of 3 feet outside the perimeter were then stripped and removed. Removals were extended to a
minimum depth of 3 feet below rough finish pad grade, exposing the underlying dense natural
Terrace Deposits throughout. All exposed bottom ofremovals and over-excavations were visually
examined, and probed to assure competent Terrace Deposit exposures suitable for receiving new
fills.
Import soils were required to complete the new wall backfilling along the western perimeter and
achieve final design grades. Import soils consisted of fine to coarse grained sandy materials.
Earth deposits generated from the onsite removals and over-excavations as well as the import soils
used as new fills and backfills predominantly consisted of silty sand to sandy (SM/SW-SP) deposits,
ranging to very low expansion potential ( expansion index less than 20, based on ASTM D4829
classification). Site new fills and backfills were properly processed, moisture conditioned to near
optimum moisture ievels, manufactured into a uniform mixture, placed in thin (approximately 8
inches thick) horizontal lifts and mechanically compacted with a hand whacker, a mini tractor
(Kubota23901), a backhoeloader(CAT 430E), and a double-drum vibratoryroller(CAT CB 214E)
to at least 95 percent and 90 percent of the corresponding laboratory maximum density per ASTM
D 1557, as required and where specified in the project soils report (minimum 95 percent compaction
was specified for pool backfill and building pad areas while minimum 90 percent compaction was
required for the western retaining_ wall backfill). Bottom of stripping, removals and over-
excavations were additionally ripped, processed and recompacted to a minimum depth of 6 inches
as a part of initial fill lift placement. Water was provided with a water hose.
Engineering observation and compaction testing of the swimming pool and wall backfilling, and
remedial pad grading operations placed within the designated areas of the property were provided
by this office from November 16, 2018 through February 20, 2019. Approximate limits of the pool
and wall backfilling and remedial pad grading works, and field compaction test locations, as roughly
established in the field by a hand level and pacing/tap measure form staking provided by others, or
relative to identifiable features located at the site and noted on the project plans are shown on the
enclosed Approximate Compaction Tests Location Map, Figure 1.
Field density tests establishing both the in-place dry densities and moisture contents were performed
in accordance with the ASTM D6938 (Nuclear Gauge) test methods, as the fill placement
progressed. Test locations were placed to provide the best possible coverage. Areas of low
compaction, as indicated by the field density tests, were brought to the attention of the project
contractor. These areas were reworked by the contractor and retested. Field compaction test results
Report of Geotechnical Engineering Observations And Compaction February 25, 2019
Testing, Remedial Pad Grading, 2637 Jefferson Street, Carlsbad, California Page 4
including pertinent bottom of over-excavation and test elevations are tabulated on the enclosed
Compaction Test Results, Figures 3 and 4. Engineering observations and compaction test results
indicated that the new fills and backfills within the approved areas (see Approximate Limits of
Grading on the enclosed Approximate Compaction Tests Location Map, Figure 1) were properly
placed and compacted to at least 95 percent and 90 percent of the corresponding maximum dry
density at the tested locations, as required and where specified.
Site preparations and remedial pad grading were conducted in substantial conformance with Chapter
18 (Soils and Foundations) and Appendix "J" (Grading) of the 2016 California Building Code
(CBC), applicable codes, the Grading Ordinances for the city of Carlsbad and current engineering
standards, as appropriate. All observations and testing were conducted by a representative from this
office under direct supervision of the project geotechnical engineering.
V. CONCLUSIONS AND RECOMMENDATIONS
In our opinion, all site excavations, swimming pool and wall backfilling and remedial building pad
grading operations, fill/backfill placement and compaction procedures were completed in
substantial conformance with the project soils reports (see References), approved plans, city of
Carlsbad grading ordinances, applicable codes and current engineering standards, and are acceptable
for their intended use.
All conclusions and recommendations including soil design parameters, geotechnical
foundation/slab designs and improvement sections provided in the referenced reports (see
References) stay unchanged, as specified therein and should be considered in the final designs and
implemented during the construction phase, where applicable and as appropriate.
VI. ADDITIONAL GEOTECHNICAL OBSERVATIONS AND TESTING
This office should be notified before any of the following operations begin in order to schedule
appropriate testing and/or field observations for confirmation and approval of the completed work:
1. Foundations and Utility Trenches: Engineering observations or testing will also be
required for the following work prior to foundation and slab concrete pours:
a) Observe the plumbing and utility trenches after the pipes are laid and prior to backfilling.
Backfill soils within trenches 12 inches or more in depth shall be compacted by
mechanical means to a minimum of 95 percent ( or 90 percent where permissible) of the
corresponding maximum dry density, unless otherwise specified. Jetting or flooding of
the backfill is not allowed. Care should be taken not to crush the utilities or pipes during
the compaction of the trench backfill.
Report of Geotechnical Engineering Observations And Compaction February 25, 2019
Testing, Remedial Pad Grading, 2637 Jefferson Street, Carlsbad, California Page 5
b) Test the plumbing trenches beneath the floor slabs for minimum compaction
requirements prior to sand and moisture barrier placement.
c) Confirm minimum foundation embedment requirements and observe bottom of the
footing trenches for proper compaction levels, including design foundation widths and
embedment depths. Building foundations adjacent to the PICP pavements should be
extended a minimum of 18 inches below the bottom of the paver section, or at least 42
inches below pad finish rough grade, whichever is more (see report dated February 14,
2017, Reference 5).
d) Confirm footing reinforcement size and placement, slab thickness and reinforcing, sand
thickness and moisture barrier placement.
2. Fine Grading and Improvements:
a) Observe placement and perform compaction testing for fills placed under any conditions
12 inches or more in depth, to include:
•
•
•
Pad perimeter contour grading for establishing positive (minimum 2 percent)
drainage away from the building.
Utility and storm trench backfills .
Spreading or placement of soil obtained from any excavation ( spoils from footings,
underground utilities, etc.).
b) Any operation not included herein which requires our testing, observation, or
conformation for submittal to the. appropriate agencies.
VII. DRAINAGE
The owner/developer is responsible for insuring adequate measures are taken to properly finish
grade the building pad after the structures and other improvements are in-place so that the drainage
waters from the graded pad and improved sites as well as adjacent properties are directed away from
the new building foundations. Storm water and surface run off water should not be allowed to flow
over the top of perimeter retaining walls, nor impact or saturate natural and graded ground surfaces,
fills and backfills, foundation bearing and subgrade soils. Only the amount of water to sustain
vegetation should be provided.
A minimum of 2 percent gradient should be maintained away from all foundations. Roof gutters
and downspouts should be installed and all discharge from downspouts should be led away from the
foundations and slab to a suitable location. Install area drains in the yards for collection and
disposal of surface water.
Report of Geotechnical Engineering Observations And Compaction February 25, 2019
Testing, Remedial Pad Grading, 2637 Jefferson Street, Carlsbad, California Page 6
Planter areas adjacent to foundations should not be allowed. Site retaining walls should be provided
with well-constructed back drainage. Planting large trees behind site retaining walls and near the
building foundations should be avoided.
It should be noted that shallow groundwater conditions may develop in areas where no such
conditions existed prior to site development. This can be contributed to by substantial increases of
surface water infiltration resulting from landscape irrigation which was not present prior to the site
redevelopment. It is almost impossible to absolutely prevent the possibility of shallow water
conditions developed from excessive landscape irrigation over the entire site, onsite drainage
facilities and site flooding due to a major storm event. Street runoff flow shall be diverted from
entering the property. We also recommend that shallow water conditions, if developed, be
immediately remedied by implementing appropriate measure, which may include the installation
of additional sub-drain(s) consisting of a 4-inch diameter perforated pipe (SDR 35) surrounded in
¾-inch rocks all wrapped in filter fabric.
The property owner(s) should be made aware that altering drainage patterns, landscaping, the
addition of patios, planters, and other improvements, as well as over-irrigation and variations in
seasonal rainfall, all affect subsurface moisture conditions, which in tum affect structural and overall
slope performance.
Project development includes the installation ofPervious (Permeable) Interlocking Concrete Pavers
(PICP) driveway with a large storage capacity for retaining all storm waters onsite, as part of the
stormwater BMP designs (see project plans). The PICP pavers require periodic monitoring and
some maintenance that is the responsibility of the current and future property owner(s), in order to
prevent any potential for failures or impacts on the nearby structures and improvements. Prolonged
excessive accumulation of water collected in the storage zone of PICP driveway, if it is allowed to
occur, can have a major adverse impact on the stability of on and off site adjacent structures and
improvements, and shall not be permitted. To reduce potential problems associated with project
PICP driveway, the following recommendations are presented:
I. Establish and carry out periodic maintenance/monitoring of the PICP driveway and
associated drainage facilities by qualified personnel. For this purpose, a regular
maintenance, upkeep, and repair program should be considered and implemented, as
necessary and appropriate. As a minimum, monitoring, and maintenance if needed, on a
semi-annual basis (before and after the rainy season) and immediately after a major storm
event should be considered.
2. Provide landscaping and slope vegetation cover consisting of drought resistant plants and
monitor the amount ofirrigation that is suggested. Irrigation should be limited to the amount
of water necessary to sustain plant life. A landscape architect may be consulted, in this
regard.
Report of Geotechnical Engineering Observations And Compaction February 25, 2019
Testing, Remedial Pad Grading, 2637 Jefferson Street, Carlsbad, California Page 7
3. Should any saturated surfaces or seepage conditions occur, the project design consultant
should be immediately notified. Additional recommendations and mitigation measures may
be necessary and should be provided at that time which may be expected to include the
installation of a subsurface or pavement underdrain(s) consisting of a 4-inch diameter (Sch
40) perforated pipe with a filter sock to allow relief from excessive accumulation of
collected water in the PICP driveway storage zone.
VIII. LIMITATIONS
Our description of the remedial grading operations, as well as observations and testing services
described herein, are limited to the work performed by this office during the period from November
16, 2018 to February 20, 2019. The recommendations provided herein have been based on our field
observations and testing, as noted. No representations are made as to the quality or extent of
materials not observed and tested.
All geotechnical information, test location and mapping on the enclosed Approximate Compaction
Tests Location Map are based on rough field measurements for the purpose of geotechnical
presentations only.
This report is issued with the understanding that the owner or his representative is responsible for
ensuring that the information and recommendations are provided to the project architect/structural
engineer and respective contractors so that they can be incorporated into the plans and implemented
at the site. Necessary steps shall be taken to ensure that the project general contractor and
subcontractors carry out such recommendations during construction.
The project geotechnical engineer should also be provided the opportunity to field verify the
foundation trenching, and foundations/slab steel reinforcement prior to placing concrete. If the
project geotechnical engineer is not provided the opportunity of making these reviews and
observations, he can assume no responsibility for misinterpretation of his recommendations.
This report should be considered valid for permit purposes for a period of six months and is subject
to review by our firm following that time. IF ANY CHANGES ARE MADE IN THE FINAL PAD
SIZE,LINESANDGRADES,BUILDINGLOCATION,ELEVATIONS,ETC.,PRIORTOTHE
CONSTRUCTION, THIS REPORT WILL BECOME INVALID AND FURTHER
ENGINEERING AND RECOMMENDATIONS WILL BECOME NECESSARY.
If you have any questions or need clarification, please contact this office at your convenience.
Reference to our Project No. FC-18-11-154 will help to expedite our response to your inquiries.
Maximum Dry Density & Optimum Moisture Content
(ASTM Dl557)
PROJECT NO: FC-18-11-154
PROJECT NAME : Arellano 4-Unit Apartment Complex
LOCATION: 2637 Jefferson Street, Carlsbad
TEST RESULTS:
Soil Type 1: Yellow to Orange-Brown Silty Sand
Maximum Dry Density: 130.3 pcf
Optimum Moisture: 9 %
Soil Type 2: Tan-Gray to Medium Brown Fine to Coarse-Grained Sand (Import# 1)
Maximum Dry Density: 139.0 pcf
Optimum Moisture: 7 %
Soil Type 3: Medium Brown to Brown Silty Fine Sand (On-Site Mixture)
Maximum Dry Density: 127.4 pcf
Optimum Moisture: 9 %
FIGURE2
COMPACTION TEST RESULTS
PROJECT NO: FC-18-11-154
PROJECT NAME:
PROJECT LOCATION:
Arellano 4-Unit Apartment Complex
2637 Jefferson Street, Carlsbad
FIELD COMPACTION TEST RESULTS (ASTM D6938):
Approximate Approximate Field
Date Test Test Test Moisture No. Location Elevation (MSL) (%) (ft)
11/16/2018 I Pool Backfill, S. W. 51.00'± 9
11/19/2018 2 Pool Backfill, S. W. 53.00'± 10
11/19/2018 3 Pool Backfill, S. W. 53.00'± 10
11/20/2018 4 Pool Backfill, S. W. 54.00'± 15
11/28/2018 5 Pool Backfill, S. W. 54.00'± 10
12/04/2018 6 Pool Backfill, S. W. 55.50'± 10
12/04/2018 7 Pool Backfill, S. W. 55.50'± 11
12/12/2018 8 Pool Backfill, S. W. 55.50'± 11
12/18/2018 9 Pool Backfill, S. W. 55.50'± 11
12/18/2018 10 Pool Backfill, S. W. 55.50'± 9
01/02/2019 11 Wall Backfill, N. W. 52.70'± 6
01/02/2019 12 Wall Backfill, N. W. 52.70'± 7
01/04/2019 13 Wall Backfill, N. W. 54.70'± 6
01/04/2019 14 Wall Backfill, N. W. 54.70'± 6
01/11/2019 15 Wall Backfill, S. W. 52.70'± 7
01/11/2019 16 Wall Backfill, S. W. 52.70'± 8
01/22/2019 17 Wall Backfill, S. W. 56.70'± 10
01/22/2019 18 Wall Backfill, S. W. 56.70'± 8
Field
Dry Soil
Density Type
(pct)
123.8 I
124.7 I
123.9 I
116.0 I
123.8 I
118.4 3
117.9 3
118.3 3
122.7 3
122.2 3
132.6 2
133.7 2
133.0 2
133.4 2
117.3 1
117.8 I
119.1 I
120.3 1
§MS GEOTECHNICAL SOLUTIONS, INC.
Max.
Dry
Density
(pct)
130.3
130.3
130.3
130.3
130.3
127.4
127.4
127.4
127.4
127.4
139.0
139.0
139.0
139.0
130.3
130.3
130.3
130.3
Relative
Compaction Comments
(%)
95 Bottom of Pool@ 49.00'±
96
95
89 Failure
95 Retest #4
93 Failure
93 Failure
93 Failure
96 Retest # 6, 7 & 8
96 Retest # 6, 7 & 8
95 Import Soils
96 Import Soils
96 Import Soils
96 Import Soils
90
90
91
92
FIGURE3
FIELD COMPACTION TEST RESULTS (ASTM D6938):
Approximate Approximate Field Field Max. Relative
Date Test Test Test Moisture Dry Soil Dry Compaction Comments No. Elevation (MSL) Density Type Density Location (ft) (%) (pcf) (pct) (%)
01 /31/2019 19 Pad Area, Easterly 55.50'± 8 123.9 I 130.3 95 Bottom of Over-Ex.@ 54.50'±
01/31/2019 20 Pad Area 55.50'± 8 123.8 1 130.3 95
01/31/2019 21 Pad Area, Westerly 55.50'± 8 121.6 3 127.4 95
01/31/2019 22 Pad Area 55.50'± 8 121.1 3 127.4 95
02/20/2019 23 Pad Area Finish Grade 9 122.7 3 127.4 96
02/20/2019 24 Pad Area Finish Grade 8 122.8 3 127.4 96
02/20/2019 25 Pad Area Finish Grade 8 121.5 3 127.4 95
02/20/2019 26 Pad Area Finish Grade 9 124.0 1 130.3 95
02/20/2019 27 Pad Area Finish Grade 10 124.2 1 130.3 95
S.MSGEOTECHNICAL SOLUTIONS, INC.
FIGURE 4