HomeMy WebLinkAboutPD 2020-0017; REAGAN ADU; FINAL SOILS REPORT; 2023-07-25July 25, 2023
City of Carlsbad
1625 Faraday Avenue
Carlsbad, CA 92008
Geotechnical Pad Certification
Attn: City Building Department
Jlmichal@aol.com
(760)-473-5052
Subject: Finished Grade Certification of ADU Pad, Retaining Wall Backfill & Adjacent Slopes
2453 Torrejon Place
Carlsbad, CA 92008
Permit# GR2020-0020
City Building Official:
In accordance with the request and authorization of project owner, representatives of Ghostrider
Inspection, Inc. have performed observation and testing services at the subject site during the period of
June 8, 2021 to July 25, 2023. Please be advised that on 07/25/2023 Ghostrider Inspection, Inc. completed
testing and observations of the ADU building pad, adjacent retaining wall, slopes & drainage on project
that has the street address of 2453 Torrejon Place, Carlsbad, CA.
Field Observation & Testing Summary:
• Earthwork construction observed and tested was performed by TLI Construction & Development,
Inc.
• Existing vegetation and improvements were removed within the proposed limits of the subject
building pads.
• Contractor over-excavated building pad to a depth of 1'. All bottoms of excavations were checked
for compaction with a ½" dia. soil probe and were found to be firm and unyielding. Native soils
were utilized to backfill and were placed in approximately 6" to 8" inch uniform lifts under the
observation and testing of a representative of Ghostrider Inspection, Inc., who was onsite on a
full time basis. (Density Results Table 1).
• Contractor placed approximately 4" of virgin Class II Base under proposed slab-on-grade per
Grading Plan notes. Imported soils were placed in a uniform lift under the observation and testing
of a representative of Ghostrider Inspection, Inc., who was onsite on a full time basis. (Density
Results Table 1).
• Field density tests were taken at periodic intervals and random locations to check the compaction
efforts by the contractor. Field density testing was performed in accordance with the sand cone
and nuclear gauge methods. Based on our observations, the test results presented herein (Table
1) should be considered representative of the level of compaction achieved during overall
preparation of the building pad. Approximate field density test locations are shown in Figure 1.
• Our field density and laboratory test results indicate that the fill materials were compacted to at
least 90% relative compaction for the ADU building pad (Based on ASTM 01557). Location and
results of compaction tests are present in Figure 1 & Table 1 respectively.
• Contractor backfilled behind retaining wall on project using a 50/50 mix of native soils and
imported 3/4" rock. This soil mix was utilized to backfill and was placed in approximately 6" to 8"
inch uniform lifts under the observation and testing of a representative of Ghostrider Inspection,
Inc. Retaining wall backfill/slope was checked for compaction with a ½" dia. soil probe and was
found to be firm and unyielding.
Date
1/19122
1/19122
1/20/22
1/20122
1120122
1125122
TABLE 1
Table 1: Log of density test results for ADU Building Pad
Maximum Dry Optimum Field
Jlmichal@aol.com
(760)-473-5052
Relative Required
Test No. Test Type Area of Work Elevation Density {pcf) Density (pcf) Moisture(%) Moisture(%) Compaction(%) Compaction(%)
1
2
3
4
5
6
SC NW Building Pad ·12" 115.4 110.7 12.5 134 959
NG NE Building Pad -12" 115.4 110.1 12.5 12.8 954
SC NW Building Pad -6" 115.4 104.1 12.5 135 90 2
SC SW Building Pad -6" 115 4 106 7 12.5 14.2 925
SC SW Building Pad -6" 11 5.4 108 5 12.5 11 1 941
NG SE Building Pad SG 132 127 3 10 11 4
FIGURE 1
*
Figure 1: Map of density test results for ADU Building Pad
Conclusion:
It is ou r opinion that the building pad, backfill against retaining walls, grading, slopes & drainage
mentioned herein has been completed in substantial conformance with the approved plans, the City of
Carlsbad specifications and the permit. Slope stability analysis was not performed for this project. If slope
stability analysis is required then revisions and further analysis will be required.
Respectfully submitted,
JLM Consulting cJ ~ cf t11'0l~
Jerry L. Michal
Consulting Geotechnical Engineer
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