HomeMy WebLinkAboutCT 2019-0002; MADISON FIVE; FINAL SOILS REPORT; 2022-06-07
07 June 2022
Mr. Michael Kootchick Job No. 18-11968
SOS Property Management
11855 Sorrento Valley Road, Suite 523
San Diego, CA 92121
Subject: Report of Additional Observations and Soil Testing
Lanshire/Madison 5 Townhomes Project
Southeast Corner of Madison Street and Oak Avenue
Carlsbad, California
Dear Mr. Kootchick:
As requested and per our work agreement, Geotechnical Exploration, Inc. hereby
presents this report of backfill observations and soil testing performed on the subject
site. Refer to the Vicinity Map, Figure No. I. The work reported herein was performed
between December 1, 2020, and May 11, 2022. We previously performed a
preliminary geotechnical investigation of the site, the results of which were presented
in our Report of Preliminary Geotechnical Investigation dated October 10, 2018. We
also issued the following documents:
1. Plan Review Letter, dated September 10, 2019;
2. Building Pad Rough Grading Completion, dated October 13, 2020.
FIELD OBSERVATIONS
1. As previously stated in the referenced October 13, 2020, report, we issued a
building pad rough grading completion letter for the project site, which
included work performed between September 24 and October 6, 2020. The
Lanshire/Madison 5 Townhomes Project Job No. 18-11968
Carlsbad, California Page 2
report details the 3½-foot removal and recompaction of the soils for Units 1
through 5. The grading was performed by C.W. Dougherty. In this report, we
address the additional observation and testing performed at the site between
December 1, 2020, and May 11, 2022.
2. Sewer trench backfill placement on Madison Street was observed and tested
on December 1 and 8, 2020.
3. The backfill placement for the waterline trench located on Oak Avenue in front
of the project site was observed on December 8, 2020. The domestic water
line trench backfill was observed on December 14, 2020. Approximately 1 foot
of sand was placed over the domestic water line. It was also observed that
the contractor placed 6 inches to 1 foot of gravel, followed by 6 to 8 inches of
native backfill soils over the storm drain. The roadway fill placement was also
observed and tested on the same date as the storm drain backfill.
4. Footing excavation bearing soils for Units 1 through 5 were observed
intermittently between January 20 and February 10, 2021. The observed
footing excavations for Units 1 through 5 were founded in suitable
recompacted fill soils. The observed footing excavations were embedded to
the proper depth indicated in the approved structural plans by HTK Structural
Engineers.
5. The backfill placement for shallow interior sewer trenches located in the
building pad were observed and probed for compaction between February 3
and February 11, 2021. The probing of the trenches indicated that the soils
were firm/dense.
Lanshire/Madison 5 Townhomes Project Job No. 18-11968
Carlsbad, California Page 3
6. The subgrade preparation and asphalt concrete placement for Madison Street
and Oak Avenue were observed and tested on January 18 and 19, 2022. The
asphalt concrete placement consisted of placing two 2½-inch lifts (i.e., 5 inches
total), followed by a 2-inch overlay, totaling 7 inches in thickness.
7. Our representative observed and tested the subgrade and base subgrade for
the new Portland Cement Concrete (PCC) cross gutter/swale and apron located
in the alley east of the building between May 4 and May 11, 2022. The concrete
placed was 6 inches in thickness on top of 6 inches of properly compacted base
and soil subgrade material.
SOIL TESTING
Representative soil samples were collected during the grading to determine
laboratory maximum dry density of the soils per ASTM D1557-12e1. Field density
tests were performed at approximate locations shown on Figure No. II, Plot Plan in
accordance with ASTM D6938-17a. The complete list of field density tests results is
shown on Table A of Figure Nos. IIIa-b, and laboratory soil compaction test results
are shown on Table B of Figure No. IIIc.
Grading equipment used for compaction consisted of a vibratory roller and pneumatic
hand tampers. A water hose was used when needed to increase the soil moisture.
Field density tests yielded a relative compaction of at least 90 percent (95 percent at
certain locations) of the maximum dry density at the tested locations with the soils
properly moisturized. On-site and imported soils were used during the observed
grading and field density testing. In general, the on-site soils consisted of red-brown
silty sand. Imported soils consisted of brown silty sand and gray well graded gravel
material. The compacted on-site and imported soils have low expansion
Lanshire/Madison 5 Townhomes Project Job No. 18-11968
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characteristics per our experience with similar soils. Hveem values for the asphalt
concrete compaction testing were provided by the asphalt concrete supplier.
Proper finish drainage for the site is to be implemented by the general contractor
prior to completing construction. Approximate limits of the graded areas are shown
in the attached Plot Plan, Figure No. II.
Any pending or future grading and earthwork should be observed by our field
representative prior to placement of wood forms and steel reinforcement, and just
prior to concrete placement. Any future utility or drainage trench backfill, or retaining
wall backfill should also be performed under the observation and testing of our firm.
Any finished subgrade testing for any pending or future exterior flatwork or driveway
should be observed and tested by our firm. A report of our observations and testing
will be provided after the additional soil-related work is performed under our
observation and testing.
SITE SUITABILITY AND COMPLIANCE
The observed and tested areas of the project site are in our professional opinion
suitable for their intended use. The adequate formational soils are, in our
professional opinion, suitable to support the new or recompacted fill and new
retaining walls.
We certify that the geotechnical engineering aspects of the observed and tested
grading are in compliance with the approved geotechnical report and approved
grading plans drawing No. 518-6A.
Lanshire/Madison 5 Townhomes Project Job No. 18-11968
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LIMITATIONS
The findings and opinions presented herein have been made in accordance with
currently accepted principles and practice in the field of geotechnical engineering in
the City of Carlsbad. No warranty, either expressed or implied, is made.
All statements in this grading report are applicable only for the grading operation
observed and tested by our firm. The firm Geotechnical Exploration, Inc. shall
not be held responsible for fill soils placed without our observations and testing at
any other time, or subsequent changes to the site by others, which directly or
indirectly cause poor surface or subsurface drainage, water erosion, and/or alteration
of the strength of the compacted fill soils.
It is not within the scope of our services to provide quality control oversight for
surface or subsurface drainage construction or retaining wall sealing and base of wall
drain construction. It is the responsibility of the contractor to verify proper wall
sealing, geofabric installation, protection board installation (if needed), drain depth
below interior floor or yard surfaces, pipe percent slope to the outlet, etc.
In the event that any changes in the nature, design, or location of the building or
improvements are planned, the conclusions and recommendations contained in this
report should not be considered valid unless the changes are reviewed and the
conclusions of this report modified or verified in writing.
Lanshire/Madison 5 Townhomes Project Job No. 18-11968
Carlsbad, California Page 6
This opportunity to be of service is sincerely appreciated. If you have any questions
regarding this letter, please contact our office. Reference to our Job No. 18-11968
will help expedite a response to your inquiry.
Respectfully submitted,
GEOTECHNICAL EXPLORATION, INC.
_______________________________ ______________________________
Jaime A. Cerros, P.E. Leslie D. Reed, President
R.C.E. 34422/G.E. 2007 P.G. 3391/C.E.G. 999
Senior Geotechnical Engineer
______________________________
Richard A. Cerros, E.I.T.
Staff Engineer
VICINITY MAP
Lanshire/Madison Street Townhomes
SE Corner of Madison Street
and Oak Avenue
Carlsbad, CA.
Figure No. I
Job No. 18-11968
SITE
Thomas Guide San Diego County Edition pg 1106-E5
Approximate Limits of Grading Subgrade and Paving AreaSewer Trench LocationWater Line and Domestic WaterLine Trench Location47.50’Bottom of Excavation Elevation (feet)47.50’47.50’49.50’49.50’49.50’Approximate Location ofField Density Test574121165398101332144465043484953455147524223182419251726221621402039411529301433353428313837322736Artificial FillOld Paralic Deposits, unit 6-7Qaf6-7QopGEOLOGIC LEGENDQaf6-7QopQaf6-7QopQaf6-7QopLanshire TownhomesSE Corner of Madison Streetand Oak AvenueCarlsbad, CA.Figure No. IIJob No. 18-11968 LEGENDScale: 1” = 20’( approximate )18-11968-p3.aiREFERENCE: This Plot Plan was prepared from an existingGRADING PLAN by HOWES/WEILER/LANDY PLANNING &ENGINEERING dated 7/8/20 and from on-site field reconnaissance performed by GEI.MADISON STREETREFERENCE: This Plot Plan is not to be used for legalpurposes. Locations and dimensions are approximate.Actual property dimensions and locations of utilitiesmay be obtained from the Approved Building Plansor the “As-Built” Grading Plans.PLOT PLAN ANDSITE SPECIFICGEOLOGIC MAPOAK AVENUEJune 2022
TABLE A ApproximateWater DryDegree of Test Elevation Content DensityCompaction Compaction No. Date of Test Test Location (Feet) (%) (pcf) (%) Curve No. Remarks 1 9/18/20 Units 3 & 4 48.5 6.8 117.994 12 9/23/20 Unit 5 48.5 9.6 115.492 13 9/24/20 Unit 1 50.5 10.1 114.891 14 9/28/20 Unit 2 50.5 9.8 114.291 15 9/28/20 Unit 2 51.5 10.6 115.091 16 9/30/20 Units 3 & 4 50 9.8 120.094 27 9/30/20 Unit 5 508.9 119.394 28 10/1/20 Units 2 & 1 52.510.1 118.69329 10/2/20 Units 3 & 4 50.8210.6 116.992 210 10/2/20 Unit 4 50.829.4 118.093211 10/2/20 Unit 5 50.8210.2 118.693 21210/5/20Unit 1 52.959.2 117.292213 10/6/20 Unit 253.2 9.6 116.691 21412/1/20Sewer Trench BackfillFSG-1.5 10.7 118.9951In Madison St.15 12/8/20 Sewer Trench Backfill49 7.6 114.691 116 12/8/20 Sewer Trench Backfill50 9.0 113.290117 12/8/20 Sewer Trench Backfill50 7.2 115.292 118 12/8/20 Sewer Trench Backfill51.5 8.5 114.091119 12/8/20 Sewer Trench Backfill51 8.0 113.991120 12/8/20 Waterline trench backfillFSG-1.0 9.6 119.09512112/14/20Domestic waterline trench50 7.6 115.09112212/14/20Domestic waterline trench50 8.4 112.99012312/14/20Domestic waterline trench52 7.9 114.39112412/14/20Domestic waterline trench52 7.0 113.69012512/14/20Roadway fill50.82 7.1 114.69112612/14/20Roadway fill53.2 8.3 115.2921271/18/22Roadway SubgradeFSG7.7 122.0971Madison Street Job No. 18-11968 Figure No. IIIaSUMMARY OF FIELD DENSITY TEST RESULTS (ASTM D1556 and/or ASTM D6938)Notes: 1) Curve number refers to Table B 2) FSG denotes finish subgrade elevation 3) FBG denotes finish base grade elevation 4) FPG denotes finish pavement grade
TABLE A ApproximateWater DryDegree of Test Elevation Content DensityCompaction Compaction No. Date of Test Test Location (Feet) (%) (pcf) (%) Curve No. Remarks SUMMARY OF FIELD DENSITY TEST RESULTS (ASTM D1556 and/or ASTM D6938)281/18/22Roadway SubgradeFSG 8.3 122.8981Madison Street291/18/22Roadway SubgradeFSG 9.1 121.3961Madison Street301/18/22Roadway AsphaltFPG-.17 -- 144.8983Madison Street311/18/22Roadway AsphaltFPG-.17 -- 145.5983Madison Street321/18/22Roadway AsphaltFPG-.17 -- 145.6983Madison Street331/18/22Roadway AsphaltFPG -- 142.8963Madison Street341/18/22Roadway AsphaltFPG -- 136.5923test failed, see #35351/18/22Roadway AsphaltFPG -- 142.1963retest of #34361/18/22Roadway AsphaltFPG -- 140.9953Madison Street371/18/22Roadway SubgradeFSG 9.1 119.0951Madison Street381/18/22Roadway AsphaltFPG -- 141.0953Madison Street391/19/22Roadway SubgradeFSG 8.3 122.0971Oak Street401/19/22Roadway AsphaltFPG-.17 0.0 142.9973Oak Street411/19/22Roadway AsphaltFPG 0.0 143.8973Oak Street425/4/22Concrete Pavement - AlleyFSG 8.2 121.2961Concrete Swale435/4/22Concrete Pavement - AlleyFSG 7.6 122.4971445/5/22Concrete Pavement - ApronFSG 5.9 119.3951455/5/22Concrete Pavement - AlleyFBG 4.1 131.8954465/5/22Concrete Pavement - GutterFBG 6.1 131.4944475/11/22AC Paving - AlleyFSG 6.2 114.7911test failed, see #48485/11/22AC Paving - AlleyFSG 6.6 123.1981retest of #47495/11/22AC Paving - AlleyFSG 6.8 121.7971505/11/22AC Paving - AlleyFBG 5.9 131.9954515/11/22AC Paving - AlleyFBG 4.3 132.0954525/11/22AC Paving - AlleyFPG 142.1963535/11/22AC Paving - AlleyFPG 140.3953 Job No. 18-11968 Figure No. IIIbNotes: 1) Curve number refers to Table B 2) FSG denotes finish subgrade elevation 3) FBG denotes finish base grade elevation 4) FPG denotes finish pavement grade
Job No. 18-11968 Figure No. IIIc TABLE B LABORATORY COMPACTION TEST RESULTS (ASTM D1557) Compaction Maximum Optimum Test Source of Dry Density Water Content Curve No. Description of Material Material (pcf) % C1 SILTY SAND (SM) Red-Brown On-site 125.8 8.3 C2 SILTY SAND (SM) (Screened Material) Import 127.5 10.0 C3* ASPHALT CONCRETE (AC) Import 148+1 C4 WELL-GRADED GRAVEL (GW), Gray Import 139.1 6.1 *Hveem provided by manufacturer