HomeMy WebLinkAboutMS 2018-0013; REDWOOD BEACH HOMES; FINAL SOILS REPORT; 2021-04-26
26 April 2021
Rincon Real Estate Group Job No. 18-11893
3005 S. El Camino Real
Del Mar, CA 92014
Attn: Mr. Kevin Dunn
Subject: Final Report of Observations and Soil Testing
Rincon-Redwood Homes
3861-3871 Garfield Street
Carlsbad, California
Dear Mr. Dunn:
Geotechnical Exploration, Inc. hereby presents this report of final grading
observations and soil testing performed at the subject site. The work reported herein
was performed between December 16, 2019, and March 29, 2021. We previously
performed a geotechnical investigation of this site, the results of which were
presented in our “Report of Preliminary Geotechnical Investigation” dated June 19,
2018. We have also issued the following documents for this site:
1. Response to Third-Party Review; dated May 15, 2019
2. Foundation Plan Review; dated May 16, 2019
3. Vertical Seepage Pit Backfill Recommendations; dated October 18, 2019
4. Report of Building Pad Rough Grading Completion; dated November 20, 2019
Rincon-Redwood Homes Job No. 18-11893
Carlsbad, California Page 2
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 No. IIIa, and laboratory soil compaction test results are
shown on Table B of Figure No. IIIb.
FIELD OBSERVATIONS
As previously stated, we issued a building pad completion letter dated November 20,
2019, in which we stated the depth of the observed and tested soil removal in the
four building pads for work performed between October 17 and November 19, 2019.
In addition, we also discussed the grouting of two seepage pits in the areas of Units
1 and 2. The following sections are for the additional observed and tested earthwork
performed between December 16, 2019 and March 29, 2021
1. Utility trench backfills were observed and tested for the sanitary sewer located
in the street on Redwood Avenue, located in the northwest portion of the lot,
as well as the sanitary sewer line that goes into the lot, east of Unit 1. The
trench on Redwood Avenue was between approximately 5 to 6 feet in depth.
Approximately 12 inches of ¾-inch-diameter gravel was placed over the pipe.
From the manhole, a 6-foot-long to 6-foot-deep trench was backfilled along
the main line and the service line. The manhole was backfilled with 4 feet of
¾-inch-diameter gravel and 3 feet of soil, up to the street finish subgrade
elevation.
Rincon-Redwood Homes Job No. 18-11893
Carlsbad, California Page 3
The upper backfill soils of the water services line located on Redwood Avenue
and the finish grade of the abandoned sewer lateral trench located on Garfield
Street were also observed and tested. That work was performed between
December 16, 2019, and January 7, 2020.
2. Building pad finish grades for Units 1 through 4 were reworked after they were
disturbed from the utility trench excavations. Our representative re-tested the
finish grades for all four units on January 16, 2020.
3. Footing excavation bottom bearing soils were observed by our representative
between February 21 and 25, 2020. The footing excavations were approved
on February 25, 2020, and were founded in dense recompacted fill soils. A
footing memo was issued to the contractor’s representative for the observed
and approved footings.
4. Curb and gutter subgrades and base grades were observed and tested between
March 2 and 4, 2021.
5. The finish subgrade for the ribbon gutter located in the center between the
four units was tested, along with the front door patio area located east of Unit
3 on March 18, 2021.
6. Finish subgrade tests were performed in the parking area on March 24 and 29,
2021. We were not requested to test finished subgrades of exterior flatwork
or hardscaped areas.
Rincon-Redwood Homes Job No. 18-11893
Carlsbad, California Page 4
Grading equipment used for compaction consisted of a backhoe with a sheepsfoot
compaction wheel 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 maximum dry
density at tested locations. Density tests were performed with a nuclear gauge
testing apparatus in accordance with ASTM D6938-17a. The maximum dry density
of the soils was determined per ASTM D1557-12e1. 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. The imported soils consisted of reddish-brown
silty sand and Class II base. The on-site and imported soils were visually classified
with low expansion characteristics per ASTM D4829.
Proper finish drainage for the site was to be implemented by the general contractor
prior to completing construction. Field density tests and approximate test locations
are shown in the attached Plot Plan, Figure No. II.
Any future grading and earthwork should be observed by our field representative
prior to form and steel reinforcing placement, 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 subgrade testing for
pending exterior flatwork should be observed and tested by our firm. A report will
be provided issued after 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 dense formational soils are, in our professional
Rincon-Redwood Homes Job No. 18-11893
Carlsbad, California Page 5
opinion, suitable to support the recompacted fill, structure foundations, and new
exterior improvements.
We certify that the soil engineering and engineering geologic aspects of the grading
are in compliance with the approved geotechnical report and the grading & drainage
plan provided by Pasco Laret Suiter & Associates for the project.
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 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.
Rincon-Redwood Homes Job No. 18-11893
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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.
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. 18-11893
will help expedite a response to your inquiry.
Respectfully submitted,
GEOTECHNICAL EXPLORATION, INC.
_______________________________ ______________________________
Jaime A. Cerros, P.E. Richard A. Cerros, E.I.T.
R.C.E. 34422/G.E. 2007 Staff Engineer
Senior Geotechnical Engineer
VICINITY MAP
Garfield Street Residences
3861-3871 Garfield Street
Carlsbad, CA.Figure No. I
Job No. 18-11893
SITE
Thomas Guide San Diego County Edition pg 1106-E7
Sidewalk Not Observed by GEISidewalk Observed 3-12-21 Footings Observed 2-21-2060Approximate Location ofField Density Test134257689575658596055151314161217525153503528244739494446302931373233363834272526232120424043191122184145485410Old Paralic Deposits (unit 6-7)Artificial FillQopQafQopQaf6-76-7QopQaf6-7QopQaf6-7QopQaf6-7Geologic Legend18-11893-p4.aiApril 2021 Garfield Street Residences3861-3871 Garfield StreetCarlsbad, CA.Figure No. IIJob No. 18-11893PLOT PLANLegendREFERENCE: This Plot Plan was prepared from an existing undatedGRADING AND IMPROVEMENT PLAN provided by COFFEY ENGINEERINGINC. and from on-site field reconnaissance performed by GEI.NOTE: This Plot Plan is not to be used for legalpurposes. Locationss and dimensions are approximate.Actual property dimensions and locations of utilitiesmay be obtained from the Approved Building Plansor the “As-Built” Grading Plans.Scale: 1” = 10’(approximate)GARFIELD STREETREDWOOD AVENUEApproximate Locationof Seepage Pit
TABLE A - SUMMARY OF FIELD DENSITY TEST RESULTS (ASTM D1556 and/or ASTM D6938)Approximate WaterDry Degree ofTestElevation Content Density Compaction Compaction No. Date of Test Test Location (Feet) (%) (pcf) (%) Curve No.Remarks1 11/1/19 Unit # 2 Building Pad 61.5 8.3 118.1 9412 11/1/19 Unit # 2 Building Pad 62.5 8.8 116.7 9213 11/1/19Unit # 1 Building Pad60.9 7.6 117.4 9314 11/4/19 Unit # 1 Seepage Pit Backfill 59.9 7.3 115.5 9115 11/4/19 Unit # 2 Seepage Pit Backfill 60.5 8.2 116.1 9216 11/5/19 Unit # 3 Building Pad 60.9 7.8 117.5 9317 11/5/19Unit # 1 Building Pad61.98.4 115.2 9118 11/5/19 Unit # 3 Building Pad 61.99.1 118.6 94 19 11/6/19 Unit # 4 Building Pad 61.58.6 114.8 9111011/15/19Unit # 4 Building Pad 62.56.4 115.2 91 11111/15/19 Unit # 1 Building PadFG (62.9)5.8 116.1 9211211/15/19Unit # 2 Building Pad FG (63.5)6.0 114.5 91 11311/15/19Unit # 3 Building Pad FG (62.9)5.9 113.9 9011411/19/19Unit # 4 Building Pad FG (63.5)7.0 119.9 92 215 12/16/19 Sanitary Sewer Trench Backfill in Redwood AvenueFSG-4 11.1 115.1 91116 12/16/19 Sanitary Sewer Trench Backfill in Redwood AvenueFSG-4 10.8 116.4 92 117 12/16/19 Sanitary Sewer Trench Backfill in Redwood AvenueFSG-3 9.9 113.8 90118 12/16/19 Sanitary Sewer Trench Backfill in Redwood AvenueFSG-3 10.5 117.5 93 119 12/16/19 Sanitary Sewer Trench Backfill in Redwood AvenueFSG-2 9.8 114.8 91 120 12/16/19 Sanitary Sewer Trench Backfill in Redwood AvenueFSG-2 8.4 115.2 91 121 12/16/19 Sanitary Sewer Trench Backfill in Redwood AvenueFSG-1 10.1 116.0 92 122 12/16/19 Sanitary Sewer Trench Backfill in Redwood AvenueFSG-1 9.7 114.6 91 12312/18/19Sanitary Sewer Trench Backfill in Redwood AvenueFSG-4 6.7 117.6 93 12412/18/19Sanitary Sewer Trench Backfill in Redwood AvenueFSG-3 7.9 118.3 94 1Figure No. IIIaJob No. 18-11893Notes: 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 - SUMMARY OF FIELD DENSITY TEST RESULTS (ASTM D1556 and/or ASTM D6938)Approximate WaterDry Degree ofTestElevation Content Density Compaction Compaction No. Date of Test Test Location (Feet) (%) (pcf) (%) Curve No.Remarks2512/18/19Sanitary Sewer Trench Backfill in Redwood AvenueFSG-2 8.2 117.2 93 12612/18/19Sanitary Sewer Trench Backfill in Redwood AvenueFSG-2 7.0 118.6 94 12712/18/19Sanitary Sewer Trench Backfill in Redwood AvenueFSG-1 6.9 116.0 92 12812/18/19Sanitary Sewer Trench Backfill in Redwood AvenueFSG-1 8.1 117.7 93 12912/18/19Sanitary Sewer Trench Backfill in Redwood AvenueFSG 7.0 119.8 95 13012/18/19Sanitary Sewer Trench Backfill in Redwood AvenueFSG 6.8 120.4 95 13112/20/19Sanitary Sewer Trench Backfill On SiteFSG-4 8.2 113.8 90 13212/20/19Sanitary Sewer Trench Backfill On SiteFSG-3 9.0 116.0 92 13312/20/19Sanitary Sewer Trench Backfill On SiteFSG-2 8.4 114.5 91 13412/20/19Sanitary Sewer Trench Backfill On SiteFSG-1 9.2 118.7 94 13512/20/19Sanitary Sewer Unit 1 LateralFSG-2 9.5 116.3 92 13612/20/19Sanitary Sewer Unit 1 LateralFSG-1 8.0 117.6 93 13712/20/19Water Services Backfill in StreetFSG-2 9.4 117.2 93 13812/20/19Water Services Backfill in StreetFSG-1 7.6 116.1 92 1391/7/20Abandoned Sanitary Sewer in Garfield StreetFSG 6.9 122.3 97 1401/7/20Abandoned Sanitary Sewer in Garfield StreetFSG 8.0 119.7 95 1411/16/20Building Pad, Unit 1FSG 9.0 117.6 93 1421/16/20Building Pad, Unit 1FSG 7.5 115.2 91 1431/16/20 Building Pad, Unit 2 FSG 8.6 117.1 93 1441/16/20 Building Pad, Unit 3 FSG 8.4 114.5 91 1451/16/20Building Pad, Unit 3FSG 7.1 119.9 95 1461/16/20Building Pad, Unit 4FSG 7.8 115.8 92 1471/16/20Building Pad, Unit 4FSG 6.0 113.5 90 1481/16/20Building Pad, Unit 5FSG 6.5 116.6 92 1493/2/21 Curb Subgrade Garfield Street FSG 7.3 114.3 90 1503/2/21 Curb Subgrade Garfield Street FSG 6.9 117.4 93 1513/2/21Curb Subgrade Redwood StreetFSG 6.2 118.9 94 1523/3/21Curb Subgrade Redwood StreetFSG 7.8 115.2 91 1Figure No. IIIb533/4/21 Curb Base Grade Garfield Street FSG 6.9 132.5 95 3Job No. 18-11893Notes: 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 - SUMMARY OF FIELD DENSITY TEST RESULTS (ASTM D1556 and/or ASTM D6938)Approximate WaterDry Degree ofTestElevation Content Density Compaction Compaction No. Date of Test Test Location (Feet) (%) (pcf) (%) Curve No.Remarks543/4/21 Curb Base Grade Redwood Street FSG 7.4 131.7 95 3553/4/21 Curb Base Grade Redwood Street FSG 6.5 132.1 95 3563/18/21 Ribbon Gutter Parking Area FSG 6.9 120.2 95 1573/18/21 Patio Front Door FSG 8.5 118.6 94 1 Unit #3583/24/21 Parking Area Subgrade FSG 8.1 119.9 95 1 East of Unit #2593/24/21 Parking Area Subgrade FSG 6.9 121.0 96 1 Between Unit #1 and #2603/29/21 Parking Area Subgrade FSG 6.0 120.4 95 1 Between Unit #1 and #3#VALUE!67#VALUE!68#VALUE!69#VALUE!70#VALUE!71#VALUE!72#VALUE!73#VALUE!74#VALUE!75#VALUE!76#VALUE!77#VALUE!78#VALUE!79#VALUE!80#VALUE!81#VALUE!82#VALUE!83#VALUE!84#VALUE!85#VALUE!86#VALUE!Figure No. IIIc87#VALUE!Job No. 18-11893#VALUE!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
Job No. 18-11893 Figure No. IIId TABLE B LABORATORY COMPACTION TEST RESULTS (ASTM D1557-12) Compaction Maximum Optimum Test Source of Dry Density Water Content Curve No. Description of Material Material (pcf) %________ 1 SILTY SAND (SM), Red-brown On-site 126.3 7.8 2 SILTY SAND (SM), Reddish Brown Import 130.8 8.2 3 CLASS II BASE Import 139.2 6.1