HomeMy WebLinkAboutCT 2017-0002; TYLER STREET RESIDENCES; FINAL SOILS REPORT; 2020-09-15@ COAST GEOTECHNICAL I CONSULTING ENGINEERING GEOLOGISTS
September 15, 2020
Elizabeth LaGrua
Tyler Street Development
4459 Hackett Avenue
Lakewood, CA 90713
Subject: FINAL GEOTECHNICAL REPORT
Proposed 8 Unit Condominium Development
3337 Tyler Street
Carlsbad, California
References: Please see Page 7
Dear Ms. LaGrua:
W.O. 710519
In response to your request, enclosed is our Final Geotechnical Report on the above referenced
property. This report presents a summary of our geotechnical observations during the grading and
construction phases. The project contractor for site development was Level 3 Construction.
PROPOSED DEVELOPMENT
Grading plans for site development were prepared by Sampo Engineering, Inc. The project included
the demolition of two existing residential structures and the construction of a three-story, eight-unit,
wood-frame condominium with enclosed parking and driveway. The three-story structure is
supported on continuous wall footings with slab-on-grade floors. A new driveway which enters from
the northeast utilized Permeable Interlocking Concrete Pavers (PICP). Grading on the site consisted
ofremoval and recompaction of approximately 4.0 feet, below existing grade, of the on-site fill, soil
and weathered Paralic Deposits.
P.O. BOX 230163 • ENCINITAS, CALIFORNIA 92023
(858) 755-8622
Coast Geotechnical
GEOTECHNICAL CONDITIONS
September 15, 2020
w.o. 710519
Page 2 of 8
The subject property is located in the Coastal Plains Physiographic Province of San Diego. The
property is underlain at relatively shallow depths by Pleistocene Old Paralic Deposits. The Old
Paralic Deposits are underlain at depth by Eocene-age sedimentary rocks commonly correlated with
the Santiago Formation on published geological maps. The Old Paralic Deposits are covered by
relatively thin soil deposits. Unweathered dense Old Paralic Deposits are considered dense and
competent, which makes it suitable for the support of foundation and fill deposits. The Old Paralic
Deposits are composed of orangish-brown fine to medium grained sand.
CONSTRUCTION PHASE
1) Rough grading for the condominium development was performed by Sims Grading from August
22 through August 30, 2019. The remedial grading was observed and tested by this firm on
August 22 through August 23, 2019, August 26, 2019, August 28, 2019 and August 30, 20 19.
2) Rough grading for the driveway was performed by Sims Grading and was observed and tested
by this firm from October 28 through October 31, 2019.
3) The continuous wall footing excavations for the condominium development were observed by
this firm on September 19, 2019, September 23, 2019, October 3, 2019 and October 7, 2019.
4) In lieu of the proposed impervious liner, the footings were deepened to approximately 4.0 feet
along the perimeter of the structures. The perimeter footings were extended approximately 8.0
inches into the Old Paralic Deposits. The footing excavations were approved by this firm
P.O. BOX 230163 • ENCINITAS, CALIFORNIA 92023
(858) 755-8622
Coast Geotechnical September 15, 2020
w.o. 710519
Page 3 of 8
provided all loose deposits are removed from the base of the excavations prior to pouring
concrete. The footing excavations were not reviewed for compliance with structural plans and
location. The deepened footings act as a subsurface cut off wall to reduce lateral migration of
infiltrated water in the pervious pavement dri veway.
5) Based on visual classification and previous laboratory testing, the mixture of soil s utilized as
compacted fill reflect an expansion potential in the very low range.
6) The utility trenches under the slab were not observed or tested in Building 2. The slab had been
poured and the Visqueen and sand blanket were placed in Building 2 prior to our observation on
October 18, 2019. The utility trench backfill under the slab for Building 1 was observed by this
firm on October 22, 2019.
7) The sewer utility trench backfill was observed and tested by this firm on November 1, 2019,
November4throughNovember 5, 2019, November 7, 2019, November 12, 2019, November 15,
2019 and November 26, 2019.
8) The building pads were graded 4.0 inches below the base of the slab in lieu of the 6.0 inches
recommended in the Geotechnical Reports. As an alternative, a minimum 15-mil vapor barrier,
as recommended in the Preliminary Geotechnical Report, was placed in direct contact with the
bottom of the proposed concrete slab. The concrete mix addressed bleeding, shrinkage and
curling. It is our understanding that the 4.0 inches of base material was composed of clean,
densely graded, granular material with a balance of fine content. These densely graded crushed
products are commonly referenced to as "crusher-run materials".
P.O. BOX 230163 • ENCINITAS, CALIFORNIA 92023
(858) 755-8622
Coast Geotechnical September 15, 2020
w.o. 710519
Page 4 of 8
9) The fire sprinkler utility trench backfill was observed and tested by this firm on December 20,
2019.
10) The electrical and gas utility trench backfill was observed and tested by this firm on May 11 ,
2020, May 14, 2020 and May 26, 2020.
11 ) The driveway easement and approach was observed and tested by this firm on May 29, 2020,
June 3, 2020, June 8, 2020 and June 29 through June 30, 2020.
12) The sidewalk and street was observed and tested by this firm from August 4 through August
5, 2020.
CONCLUSIONS
The geotechnical conditions encountered on the site were in substantial conformance with those
conditions anticipated in the Preliminary Geotechnical Report. In general, the recommendations of
the geotechnical reports were implemented during the grading and construction phases. Perimeter
footings were deepened to act a subsurface cut off wall to reduce lateral migration ofinfiltrated water
from the pervious pavement driveway section.
The recommended 6.0 inch gravel/sand blanket was revised since the graded pad did not
accommodate a 6.0 inch section below the slab. The revised section included a vapor barrier in
direct contact with the bottom of the slab and underlain by 4.0 inches of "crusher-run materials".
P.O. BOX 230163 • ENCINITAS, CALIFORNIA 92023
(858) 755-8622
Coast Geotechnical September 15, 2020
w.o. 710519
Page 5 of 8
Footings and slabs on grade should be protected from root and/or moisture migration. Undermining
and pressure from roots and/or saturated soil conditions from infiltration can adversely affect
foundations and slabs on grade. Irrigation should be limited to that amount necessary to sustain plant
life.
LIMITATIONS
Our geotechnical services during the grading and construction phases were limited to the areas
discussed. Geotechnical analysis of storm water infiltration was limited in scope. The long term
effects ofinfiltration cannot be predicted with certainty and can only be evaluated through usage and
time. However, in no respect do we guarantee or warrant the future performance of infiltration
systems.
P.O. BOX 230163 • ENCINITAS, CALIFORNIA 92023
(858) 755-8622
Coast Geotechnical September 15, 2020
w.o. 710519
Page 6 of 8
If you have any questions regarding this report, please contact our office. Reference to our Job No.
710519 will help expedite a response to your inquiry.
Respectfully submitted,
COAST GEOTECHNICAL
Kevin McFarland
Project Geologist
/JW,5~
Mark Burwell, C.E.G.
Engineering Geologist
Enclosures: Compaction Test Results
Grading Plan
J~LW
Vithaya Singhanet, P.E.
Geotechnical Engineer
P.O. BOX 230163 • ENCINITAS, CALIFORNIA 92023
(858) 755-8622
Coast Geotechnical
REFERENCES
1 Response to DSS Geotechnical & Architectural Peer Review
Dated September 25, 2019
Proposed 8 Unit Condominium Development
3337 Tyler Street
Carlsbad, California
Prepared by Coast Geotechnical
Dated October 10, 2019
2. NOTICE OF FOOTING EXCAVATION OBSERVATION
Proposed Residential Structures (Eastern Halt)
3337 Tyler Street
Carlsbad, California
Prepared by Coast Geotechnical
Dated October 7, 2019
3. NOTICE OF FOOTING EXCAVATION OBSERVATION
Proposed Residential Structures (Western Halt)
3337 Tyler Street
Carlsbad, California
Prepared by Coast Geotechnical
Dated September 24, 2019
4. SUBSURFACE CUT OFF WALLS
Proposed 8 Unit Condominium Development
3337 Tyler Street
Carlsbad, California
Prepared by Coast Geotechnical
Dated September 19, 2019
5. ROUGH GRADING REPORT
Proposed 8 Unit Condominium Development
3337 Tyler Street
Carlsbad, California
Prepared by Coast Geotechnical
Dated September 5, 2019
P.O. BOX 230163 • ENCINITAS, CALIFORNIA 92023
(858) 755-8622
September 15, 2020
w.o. 710519
Page 7 of 8
Coast Geotechnical
REFERENCES {Continued)
September 15, 2020
W.O. 710519
Page 8 of 8
6. Sampo Engineering, 04/29/19, Grading Plan for Tyler Street Residences, APN: 204-070-1 0-11,
Drawing No. 508-SA.
7. Helenschmidt Geotechnical, Inc., 03/20/19, Placement of Geo-Fabric in Areas of Permeable
Pavers/Infiltration System for Proposed 8-Unit Condominium Development.
8. Helenschmidt Geotechnical, Inc., 03/07/19, (Revised from 01/22/17), Geotechnical Review of
Tentative Map and Preliminary Grading Plan for Proposed 8-Unit Condominium Development.
9. Helenschmidt Geo technical, Inc., 10/24/18, Geotechnical Review of Grading Plan and Structural
Plans for Proposed 8-Unit Condominium Development.
l 0. Helenschmidt Geotechnical, Inc., 01/19/18, (Revised from 06/27 /16), Subsurface Investigation
for Geotechnical Design for Proposed 8-Unit Condominium Development.
11. Helenschmidt Geotechnical, Inc., 01/22/17, Geotechnical Review of Tentative Map and
Preliminary Grading Plan for Proposed 8-Unit Condominium Development.
12. Helenschmidt Geotechnical, Inc., 06/27/16, Subsurface Investigation for Geotechnical Design
for Proposed 8-Unit Condominium Development.
P.O. BOX 230163 • ENCINITAS, CALIFORNIA 92023
(858) 755-8622
ENCLOSURES
COAST GEOTECHNICAL ~ CONSUL TING ENGINEERING GEOLOGISTS ~ 5931 Sea Lion Place, Suite 109-Carlsbad, Ca 92010
(858) 755-8600
Job Name: Elizabeth LaGrua Dates:
Project#: 710519
Laboratory Maximum Dry Density/ Optimum Moisture Content Test Results (ASTM D1557):
Soil Type 1: Orangish brown sand (on-site) Maximum Dry Density= 131.0 pcf
Soil Type 2: Base -obtained from plant
Soil T~ Recycled Base -obtained from plant
Test#/date Max Dens Test Location/Sta# Elevation
1 -8/22/19 131 Residence B 43
2 131 Residence C 43
3 131 Garage A 43
4 restest of 1 131 Residence B 43
5 retest of 2 131 Garage B 43
6 retest of 3 131 Garage C 43.5
7 131 Residence C 43.5
8 131 Residence D 44
9 -8/23/19 131 Garage A 44
10 131 Residence A 44
11 131 Garage D 44
12 131 Garage A 43
13 131 Garage D 43
14 131 Garage C 44
15 131 Residence D 44.5
16 131 Residence C 44.5
17 retest of 10 131 Residence A 44.5
18 131 Garage B 45
19 131 Residence B 45
20 131 Residence H 41.5
21 -8/26/19 131 Residence H 41.5
Maximum Dry Density= 142.9 pcf
Maximum Dry Density= 135.0 pcf
Wet Density Dry density % Moisture
122.3 114.2 7.1
120.5 112.7 6.9
127.9 116.2 10.1
126.0 117.9 6.9
131.6 122.4 7.5
128.1 118.3 8.3
131.0 119.4 9.7
129.4 118.0 9.7
126.4 118.7 6.5
120.7 114.0 5.9
128.2 120.6 6.3
130.3 119.9 8.7
128.2 118.2 8.5
130.1 119.6 8.8
129.8 119.0 9.1
127.7 117.9 8.3
127.6 118.6 7.6
129.9 118.0 10.1
128.2 118.2 8.5
136.1 125.4 8.1
132.2 123.2 7.3
8/22/2019 to 8/05/2020
Optimum Moisture Content= 8.5%
Optimum Moisture Content = 7.0%
Optimum Moisture Content= 7.0%
Requirment % Compaction Pass/Fail
90 87 Fail
90 86 Fail
90 89 Fail
90 90 Pass
90 93 Pass
90 90 Pass
90 91 Pass
90 90 Pass
90 91 Pass
90 87 Fail
90 92 Pass
90 92 Pass
90 90 Pass
90 91 Pass
90 91 Pass
90 90 Pass
90 91 Pass
90 90 Pass
90 90 Pass
90 96 Pass
90 94 Pass
Test#/date Max Dens Test Location/Sta# Elevation Wet Density Dry density % Moisture Requirment % Compaction Pass/Fail
. 22 ' . .._. ·131. Residence:E&F' .42-J5' 133~1 · ···:122.1 8.5 .· .. 90 94 P.ass . ' '
23 131 Residence E&F 42.5 130.1 121.1 7.4 90 92 Pass
24 · 131 · G·arage· E . '132~6 . .. · ·• 122.9 7.9 .. 90 94 · · · Pass 42~5 ..
25 131 Garage E 42.5 134.2 124.0 8.2 90 95 Pass
26 _. 8/27 /19 · ', ·131 Residence· ti· __ 42~5 125.9 116.S· 8.1 90 89 Fail
27 retest of 26 131 Residence H 42.5 129.7 120.2 7.9 90 92 Pass
28·. 1~1 Residence G. 43~5-.132,6', 122.4 8.3 90 93 Pass
29 131 Residence F 44 135.5 125.9 7.6 90 96 Pass
30 131 Resid~nc_e E· · " 44 135.4' .. 124_.l 9.1: 90 95 Pass
31-8/28/19 131 Res H 44 132.6 122.4 8.3 90 93 Pass
32 · . 131 Rest;· 4~ 131.1 121.7 7.7 90 93 Pass
33 131 ResD 45 129.9 120.6 7.7 90 92 Pass
34 -131 ResB 45 133.2 122.9 8.4 90 94 Pass
35 131 Res A 45 135.3 124.2 8.9 90 95 Pass
35-8/30/19 131 ResH FSG 134.8 124.0 8.7 90 95 Pass
36 131 Res F FSG 133.7 122.4 9.2 90 93 Pass
3.7 131 Res E FSG 133.2 123.2 8.1 · 90 94 Pass
38 131 Res D FSG 130.0 120.7 7.7 90 92 Pass
39 131 ResB FSG'. . 131.5 121.9 7.9 90 93 Pass
40 131 Res A FSG 133.9 123.5 8.4 90 94 Pass
41.;.10/29/19 131 Driveway-N 42 135.1 126.1 7.1 90 96 Pass
42 131 Driveway -Mid 43 133.8 124.8 7.2 90 95 Pass
43 131 Driveway-S 43 135.8 126.2 7.6 90 96 Pass
44-10/30/19 131 Driveway-S 43 133.9 125.5 6.7 90 96 Pass
45 131 Driveway -Mid 45 135.1 126.5 6.8 90 97 Pass
46 131 Driveway-N 43 135.6 126.4 7.3 90 96 Pass
47 131 Driveway-N 44 132.9 124.9 6.4 90 95 Pass
48-11/1/19 131 Sewer-Send 40 137.2 126.1 8.8 90 96 Pass
49 131 Sewer-Send 41 137.3 125.3 9.6 90 96 Pass
50 131 Sewer-Send 42 136.9 124.2 10.2 90 95 Pass
51 131 Sewer-Mid 40 135.0 124.8 8.2 90 95 Pass
52 131 Sewer-Mid 41 134.8 125.7 7.2 90 96 Pass
53 131 Sewer-N end 42 136.4 124.9 9.2 90 95 Pass
Test#/date Max Dens Test Location/Sta# Elevation Wet Density Dry density % Moisture Requirment % Compaction Pass/Fail
54 131 Sewer·;.; ·N:end Gra·de 13~.5 127.3 .7.2 90 97 Pass
55 131 Sewer-N end Grade 135.4 126.5 7 90 97 Pass
56~11/4/19 131 Se.werlateral 44 · 134~1 121.0 .. 10.8 90. 92 Pass
57 131 Sewer Lateral 44 131.4 120.7 8.9 90 92 Pass
58 131 Sewer-Jv'lid. · · 45· . 130.7,; 122.6 6.6 ·90; 94 Pass
59 131 Sewer-Mid Grade 127.6 120.0 6.3 90 92 Pass
60 131 Sewer"'.Send 45. . 125A 118.0 6.3 90 90 Pass
61 131 Sewer-Send Grade 125.5 118.4 6 90 90 Pass
62;.11/5/19 131 Sew~r-Seod 45 126.9·· 118.7 6.9 90 91 Pass
63 131 Sewer -Street 43 127.8 119.0 7.4 90 91 Pass
64-11/7/19 131 Sewer.;.Send 42 133-.6 121.2 10~2 90 93 Pass
65 131 Sewer-Send 44 134.9 122.9 9.8 90 94 Pass
66 131 Sewer MH -Site 45 132.4 119.0 11.3 90 91 Pass
67 131 Sewer MH-Street 41 132.6 118.5 11.9 90 90 Pass
68 131 Sewer MH _.:;Street 44 136.3 123.2 10.6 90 94 ·Pass
69 131 Sewer MH -Street 46 133.9 120.1 11.5 90 92 Pass
70 -11/12/19 131 Sewer Lateral Grade. 127.9 118.8 1.7 90 91 Pass
71 131 Sewer Lateral Grade 130.7 122.4 6.8 90 93 Pass
72 131 Sewer Lateral Grade 125.4 118.0 6.3 90 90 Pass
73 131 Sewer Lateral Grade 130.1 118.3 10 90 90 Pass
74 -11/15/19 131 Utilities Grade· 132.7 118.9 11.6 90 91 Pass
75 131 Utilities Grade 131.0 119.0 10.1 90 91 Pass
76 -11/26/19 131 Utilities Grade 136.4 120.1 13.6 90 92 Pass
77 131 Utilities Grade 135.0 119.8 12.7 90 91 Pass
78 -12/20/19 131 Fire Sprinkler 45 129.4 118.6 9.1 90 91 Pass
79 131 Fire Sprinkler Grade 132.1 122.8 7.6 90 94 Pass
80 131 Fire Sprinkler 45 134.7 122.8 9.7 90 94 Pass
81 131 Fire Sprinkler Grade 131.3 121.0 8.5 90 92 Pass
82 131 Fire Sprinkler 45 131.6 119.6 10 90 91 Pass
83 131 Fire Sprinkler 45 126.0 117.8 7 90 90 Pass
84-5/11/20 131 Electrical Line 42 123.4 118.0 4.6 90 90 Pass
85 131 Electrical Line 42 124.3 118.4 5 90 90 Pass
86-5/14/20 131 Electrical Line 43 128.3 120.7 6.3 90 92 Pass
Test#/date Max Dens Test Location/Sta# Elevation Wet Density Dry density % Moisture Requirment % Compaction Pass/Fail
87 131 Electrical _Line 43 126.1, 119~2. 5.8 90 91 ·.Pass
88-5/29/20 131 Easement SG 131.2 125.1 4.9 90 95 Pass
89 131: " E_asement· · SG 125.5 ·118~2. _ : 6~-2·, . _90 90 .. Pass
90 131 Easement SG 127.1 119.5 6.4 90 91 Pass
91-6/3/20 . .1-3t·· E~semeijt.· .. sG·--128~3 :· -;· 121.3 s~8 · . 90 93 Pass
92 131 Easement SG 129.6 121.0 7.1 90 92 Pass
93 -6/29/20 · 131 ·oriveway·Approach SG 142.3 128.7 10.6 95 98 Pass
94-6/30/20 142.9 Driveway Approach BG 149.5 135.9 10 95 95 Pass
-95 -8/4/20 -135 Side.walk ,. BG 142-.2 128.1 .11 95 95 Pass.
96-8/5/20 135 Existing Street BG 142.1 132.8 7 95 98 Pass
97 135 Existing Street :BG 135.5 128.3 5.6 95 95 Pass
98 135 Existing Street BG 136.9 129.9 5.4 95 96 Pass