HomeMy WebLinkAboutMS 16-06; CARLSBAD VILLAGE LOFTS; UPDATED PRELIMINARY GEOTECHNICAL RECOMMENDATIONS AND GRADING PLAN REVIEW; 2019-02-28 (2)(v\
CTE
Construction Testing & Engineering, Inc.
V -
Inspection I Testing I Geotechnical I Environmental & Construction Engineering I Civil Engineering I Surveying
February 28, 2019
Wermers Properties
Attn: Austin Wermers
5080 Shoreham Place, Suite 105
San Diego California 92122
(858) 623-4958
CTE Job No. 10-14798G
MAR 04 2019
LAND )EVELOPMENT
EiG1NEERIG
Via Email: AustinW@wermerscompanies.com
Subject: Updated Preliminary Geotechnical Recommendations and Grading Plan Review
Proposed Carlsbad Village Lofts
1044 Carlsbad Village Drive (APNs: 203-320-3200, -3900, & -4700)
Carlsbad, California
Mr. Wermers:
Construction Testing and Engineering, Inc. (CTE) has reviewed the referenced and attached
geotechnical investigation report for the Proposed Carlsbad Village Drive Apartments with
regard to utilization as preliminary recommendations for the proposed project at the subject site.
Based on the review, recommendations presented in the referenced geotechnical investigation
report can be used for preliminary design.
As required and requested, update recommendations for various proposed improvements are
presented herein. Recommendations in the referenced report not specifically modified or
provided herein remain applicable for use during project design and construction. However,
CTE reserves the right to further modify recommendations and/or provide additional
recommendations based on the actual conditions encountered at the site during earthworks and
construction.
1.0 UPDATED GEOTECHNICAL RECOMMENDATIONS
1.1 Pervious Payers
The following geotechnical recommendations for the installation of the proposed pervious payers
are provided for the subject site. The recommendations are based on an assumed "R"-Value of
the subgrade materials to underlie to pervious payers and anticipated traffic conditions within the
proposed driveway. The assumed "R"-Value is presented in Appendix C, Laboratory Results, of
the referenced report. As shown in Tables 1.11 the aggregate base section thicknesses are based
on an assumed design "R"-Value of 40 or greater and Traffic Index (TI) of 5.0
1441 Montiel Road, Suite 115 J Escondido, CA 92026 I Ph(760)746-4955 j Fax(760)746-9806 I www.cte-inc.
Mb I(rO6C)
Updated Preliminary Geotechnical Recommendations and Grading Plan Review Page 2
Proposed Carlsbad Village Lofts
1044 Carlsbad Village Drive (APNs: 203-320-3200, -3900, & -4700)
Carlsbad, California
February 28, 2019 CTE Job No. 10-14798G
Recommendations provided herein are based on the assumption that the upper foot of compacted
fill subgrade and overlying aggregate base materials are properly compacted to a minimum 95%
relative compaction at a minimum of two percent above optimum moisture content (as per
ASTM D 1557). Beneath proposed pavement areas, loose or otherwise unsuitable soils are to be
removed to the depth of competent native material as recommended in Section 5.2 of the
referenced report.
FABLE I 1
RECOMMENDED PERVIOUS Pk\ERS OR PCCF1\ EL\IENT SEC [ION THICKNESSES
Traffic Area Assumed Tested Pervious Payers
Traffic Subgrade
Pervious Permeable Index "R"-Value
Paver Aggregate
Thickness Base
(INCHES)
Auto Drive Areas
(Driveway) 5.0 40+ 3.0 8.0
Including Infrequent (minimum)
Emergency Vehicles
1.2 Percolation Testing
Percolation testing was completed during the initial geotechnical investigation in December of
2015. Section 3.3, Percolation Testing of the referenced report describes general test methods
and provides Percolation Test Results. The following evaluation was performed in general
accordance with Appendix C of the Model BMP Design Manual for the San Diego Region
"Geotechnical and Groundwater Investigation Requirements", dated January 2018.
1.2.1 Percolation Test Methods
The percolation tests were performed in general accordance with methods approved by
the San Diego Region BMP Design Manual with a presoak period of approximately 20 to
21 hours. Percolation test results and calculated infiltration rates are presented below in
Table 1.2.
1.2.2 Calculated Infiltrated Rate
As per the San Diego Region BMP design documents (2018) infiltration rates are to be
evaluated using the Porchet Method. San Diego BMP design documents utilized the
Porchet Method through guidance of the County of Riverside (2011). The intent of
calculating the infiltration rate is to take into account bias inherent in percolation test
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. I Updated Preliminary Geotechnical Recommendations and Grading Plan Review Page 3
Proposed Carlsbad Village Lofts
1044 Carlsbad Village Drive (APNs: 203-320-3200, -3900, & -4700)
Carlsbad, California
February 28, 2019 CTE Job No. 10-14798G
borehole sidewall infiltration that would not occur at a basin bottom where such sidewalls
are not present.
The infiltration rate (Ii) is derived by the equation:
it = AH 7tr2 60 = AH 60 r
At(iti2 +2ltlHav9) At(r+2Havg)
Where:
I = tested infiltration rate, inches/hour
AH = change in head over the time interval, inches
At = time interval, minutes
* r = effective radius of test hole
Havg = average head over the time interval, inches
Given the measured percolation rates, the calculated infiltration rates are presented with
and without a Factor of Safety applied in Table 1.2 below. The civil engineer of record
should determine an appropriate factor of safety to be applied via completion of
Worksheet D.5-1 of Appendix County of San Diego "Best Management Practice Design
Manual", Appendix D or other approved methods. CTE does not recommend using a
factor of safety of less than 2.0. Field Data and Worksheet 1-8 are included as
attachments.
TABLE 1.2
RESULTS OF PERCOLATION io. TESTING ENG WITH FACTOR OF SAFETY APPLIED
T 1. Test Depth Soil Type* oi ype Percolation Infiltration Infiltration Rate
Test Rate (inches Rate with FOS of 2
Location per hour) (inches per Applied (inches
hour) per hour)
(inches) Case
P-i 23.625 III Qop 3.500 5.895 2.947
P-2 19.625 III Qudf 0.500 0.421 0.211
P-3 27.25 III Qudf 2.500 3.636 1.818
P-4 24.5625 III Qop 1.625 1.576 0.788
P-5 27.25 III Qop 0.625 0.122 0.061
P-6 59 III Qop 5.250 0.139 0.070
\\ESC_SER\TER\Projects\10-14798G\Rpt_Update Geo & Plan Revdoc
Updated Preliminary Geotechnical Recommendations and Grading Plan Review Page 4
Proposed Carlsbad Village Lofts
1044 Carlsbad Village Drive (APNs: 203-320-3200, -3900, & -4700)
Carlsbad, California
February 28, 2019 CTE Job No. 10-14798G
1.3 Seismic Design Criteria
The seismic ground motion values listed in the Table 5.9 of the referenced geotechnical report
were derived in accordance with the ASCE 7-10 Standard and 2013 CBC. If seismic ground
motion values in accordance with ASCE 7-10 Standard and 2016 CBC are required, the values
presented in the aforementioned Table 5.9 are applicable.
2.0 GRADING PLAN REVIEW
As requested, Construction Testing & Engineering, Inc. (CTE) has reviewed the referenced
grading plans for the subject project. The object of our review was to identify potential conflicts
with the recommendations of our referenced geotechnical report. It is our conclusion that the
reviewed plans are in substantial conformance with recommendations presented in our
referenced soils report, and the proposed development is suitable for the subject site.
3.0 LIMITATIONS
This letter is subject to the same limitations as previous CTE geotechnical documents issued for
the subject project. CTE's conclusions and recommendations are based on an analysis of the
observed conditions. If conditions different from those described in the reports are encountered
during construction, this office should be notified and additional recommendations, if required,
will be provided.
\\ESC._SERVER\Projects\lO-14798G\Rpt_Update Gen & Plan Revdoc
Updated Preliminary Geotecimical Recommendations and Grading Plan Review Page 5
Proposed Carlsbad Village Lofts
1044 Carlsbad Village Drive (APNs: 203-320-3200, -3900, & -4700)
Carlsbad, California
February 28, 2019 CTE Job No. 10-14798G
The opportunity to be of service on this project is appreciated. If you have any questions
regarding this report, please do not hesitate to contact the undersigned.
Respectfully submitted,
CONSTRUCTION TESTING & ENGINEERING, INC.
TF
No.2665 t\
EXP.12/31/20
S.. I
No.1890 cc CER71FIED
*\ oto /
r ENGINEERING si I
\Exp.5/31/19!
Dan T. Math, GE# 2665 AXf Jay F. Lynch, CEG #1890
Vice President, Principal Principal Engineering Geologist
Matthew Martinez
Staff Geologist
MDM/JFL/DTM:nri
Attachments:
Appendix I: Field Data/Percolation to Infiltration Calculations (2 Sheets Total)
Appendix II: Worksheets 1-8 (4 Sheets Total)
Appendix III: Preliminary Geotechnical Report, dated January 27, 2016
References:
Grading Plan Sheets lthrough 7, City of Carlsbad Project No. MS 16-06, Drawing 515-5A
Carlsbad Village Lofts
1044 Carlsbad Village Drive
Carlsbad, California
Prepared by SB&O Engineering,
\\ESC_SERVER\Projects\IO-l4798G\Rpt_Update Geo & Plan Revdoc
Project: Carlsbad Village Lofts
Project No.: 10-14798G Tables P-i
Percolation Field Data and Calculated Rates
P-i Total Depth: 23.625 inches
Test Water Water Incremental Percolation Percolation Time Interval Test Refill Level Level Water Level Rate Rate Time Initial/Start End/Final Change
(minutes) Depth /Inches Depth /Inches Depth /Inches (inches) inches/minute inches/hour
8:55:00 Initial None 23.63 initial -
9:25:00 30 24.25 23.63 26.50 2.88 0.096 5.750
9:55:00 30 12.0625 24.25 26.00 1.75 0.058 3.500
10:25:00 30 23.9375 12.06 25.63 13.56 0.452 27.125
10:55:00 30 23.8125 23.94 25.50 1.56 0.052 3.125
11:25:00 30 23.3125 23.81 25.25 1.44 0.048 2.875
11:55:00 30 23.5 23.31 25.19 1.88 0.063 3.750
12:25:00 30 23.5625 23.50 25.25 1.75 0.058 3.500
12:55:00 30 12 23.56 25.31 1.75 0.058 3.500
P-2 Total Depth: 19.625 inches
Test
Interval
Time
(minutes)
Initial
30
30
30
30
30
30
30
30
Test
Interval
Time
(minutes)
Initial
30
30
30
30
30
30
30
Water Water
Test Refill Level Level
Initial/Start End/Final
Depth /Inches Depth /Inches Depth /Inches
None 19.63 initial
19.625 19.63 19.88
19.4375 19.63 19.63
19.375 19.44 19.75
19.125 19.38 19.63
19.0625 19.13 19.38
19.25 19.06 19.25
19.125 19.25 19.56
NO 19.13 19.38
Water Water
Test Refill Level Level
Initial/Start End/Final
Depth /Inches Depth /Inches Depth /Inches
None 27.56 initial
27.75 27.56 29.19
27.625 27.75 29.00
27.75 27.63 28.88
27.1875 27.75 29.00
26.0625 27.19 28.38
27.0625 26.06 28.31
26.9375 27.06 28.44
Incremental Percolation Percolation Water Level Rate Rate Change
(inches) inches/minute inches/hour
0.250 0.008 0.500
0.000 0.000 0.000
0.313 0.010 0.625
0.250 0.008 0.500
0.250 0.008 0.500
0.188 0.006 0.375
0.313 0.010 0.625
0.250 0.008 0.500
Total Depth: 27.25 inches
Incremental Percolation Percolation Water Level Rate Rate Change
(inches) inches/minute inches/hour
1.63 0.054 3.250
1.25 0.042 2.500
1.25 0.042 2.500
1.25 0.042 2.500
1.19 0.040 2.375
2.25 0.075 4.500
1.38 0.046 2.750
Time
8:50:00
9:20:00
9:50:00
10:20:00
10:50:00
11:20:00
11:50:00
12:20:00
12:50:00
P-3
Time
8:45:00
9:15:00
9:45:00
10:15:00
10:45:00
11:15:00
11:45:00
12:15:00
fl
12:45:00 30 NO 26.94 28.19 1.25 0.042 2.500
P-4 Total Depth: 24.5625 inches
Test Water Water Incremental Percolation Percolation Time Interval Test Refill Level Level Water Level Rate Rate Time Initial/Start End/Final Change
(minutes) Depth /Inches Depth /Inches Depth /Inches (inches) inches/minute inches/hour
8:40:00 Initial None 24.56 initial -
9:10:00 30 24.125 24.56 26.38 1.81 0.060 3.625
9:40:00 30 23.9375 24.13 25.31 1.19 0.040 2.375
10:10:00 30 24.1875 23.94 25.00 1.06 0.035 2.125
10:40:00 30 24.3125 24.19 25.06 0.88 0.029 1.750
11:10:00 30 23.75 24.31 25.31 1.00 0.033 2.000
11:40:00 30 23.4375 23.75 24.63 0.88 0.029 1.750
12:10:00 30 24.125 23.44 24.38 0.94 0.031 1.875
12:40:00 30 NO 24.13 24.94 0.81 0.027 1.625
P-S Total Depth: 27.25 inches
Test Water Water Incremental Percolation Percolation Time Interval Test Refill Level Level Water Level Rate Rate Time Initial/Start End/Final Change
(minutes) Depth /Inches Depth /Inches Depth /Inches (inches) inches/minute inches/hour
8:35:00 Initial None 19.13 initial -
9:05:00 30 19.1875 19.13 19.69 0.56 0.019 1.125
9:35:00 30 18.6875 19.19 19.69 0.50 0.017 1.000
10:05:00 30 18.6875 18.69 19.19 0.50 0.017 1.000
10:35:00 30 18.875 18.69 19.13 0.44 0.015 0.875
11:05:00 30 18.8125 18.88 19.38 0.50 0.017 1.000
11:35:00 30 18.75 18.81 19.25 0.44 0.015 0.875
12:05:00 30 18.875 18.75 19.13 0.38 0.013 0.750
12:35:00 30 NO 18.88 19.19 0.31 0.010 0.625
P-6 Total Depth: 59 inches
Test Water Water Incremental Percolation Percolation Time Interval Test Refill Level Level Water Level Rate Rate Time Initial/Start End/Final Change
(minutes) Depth /Inches Depth /inches Depth /Inches (inches) inches/minute inches/hour
9:00:00 Initial None 22.56 initial -
9:30:00 30 20.25 22.56 28.19 5.63 0.188 11.250
10:00:00 30 20.1875 20.25 24.63 4.38 0.146 8.750
10:30:00 30 20.4375 20.19 23.81 3.63 0.121 7.250
11:00:00 30 20.875 20.44 23.50 3.06 0.102 6.125
11:30:00 30 21 20.88 23.63 2.75 0.092 5.500
12:00:00 30 20.8125 21.00 23.69 2.69 0.090 5.375
12:30:00 30 20.9375 20.81 23.63 2.81 0.094 5.625
13:00:00 30 NO 20.94 23.56 2.63 0.088 5.250
Worksheet 1-8 : Categorization of Infiltration Feasibility Condition
irnuitj Jiti __
Part I I dli iJl11111tUU1l I Ct41J1LIL\ fLLtllid (iiLc11a
Would infiltration of the full design volume be feasible trorn a physical perspective without any undesirable
consequences that cannot be reasonably mitigated?
Criteria Screening Question Yes No
Is the estimated reliable infiltration rate below proposed facility locations
1 greater than 0.5 inches per hour? The response to this Screening Question shall
be based on a comprehensive evaluation of the factors presented in Appendix X
C.2 and Appendix D.
Provide basis: The NRCS soils across the site are all Type B soils with medium surface runoff. The site soils are
consistent with the NRCS mapped soil types based on site explorations and percolation testing.
Two soil types were present in the area of the proposed development, Quaternary Undocumented
Fill and Old Paralic Deposits.
Four percolation tests were completed within the Old Paralic Deposits. The calculated infiltration
rates (with an applied factor of safety of 2) ranged from approximately to 0.070 to 2.947 inches
per hour.
Twp percolation tests were completed within the Quaternary Undocumented Fill, The calculated
infiltration rates (with an applied factor of safety of 2) ranged from approximately to 0.211 to
1.818 inches per hour.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide
narrative discussion of study/data source applicability.
Can infiltration greater than 0.5 inches per hour be allowed without increasing
risk of geotechnical hazards (slope stability, groundwater mounding, utilities, or
2 other factors) that cannot be mitigated to an acceptable level? The response to X
this Screening Question shall be based on a comprehensive evaluation of the
factors presented in Appendix c.2.
Provide basis: Lining the sides of the BMP's with impermeable geofabric liner is recommended to reduce lateral
migration of infiltrate. The lining should extend to the maximum depth of utility trenches and
foundation excavations within 100 feet of the proposed basin.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide
narrative discussion of study/data source applicability.
Critia Sctcn t Ic \ j
Can infiltration greater than 0.5 inches per hour be allowed without increasing
risk of groundwater contamination (shallow water table, storm water pollutants
3 or other factors) that cannot be mitigated to an acceptable level? The response X
to this Screening Question shall be based on a comprehensive evaluation of the
factors presented in Appendix C.3.
Provide basis: Based on site explorations and knowledge of the site area, groundwater is anticipated to be deeper
than at least 10 feet below the bottom of the planned basin bottoms. Infiltration at the site is not
anticipated to increase the risk of groundwater contamination. According to Geotracker online (a
State of California on line resource for listings of regulated contaminated sites), there are no open
LUST cases in the site area that could impact the site. The proposed development is not industrial
and capture of surface waters is not anticipated to increase the risk of groundwater contamination.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide
narrative discussion of study/data source applicability.
Can infiltration greater than 0.5 inches per hour be allowed without causing
potential water balance issues such as change of seasonality of ephemeral
4 streams or increased discharge of contaminated groundwater to surface waters? X
The response to this Screening Question shall be based on a comprehensive
evaluation of the factors presented in Appendix C.3.
Provide basis: Infiltration at the site is not anticipated to cause potential water balance issues and not anticipated
to change the seasonality of ephemeral streams. There are no ephemeral streams in the site area.
Site discharge is not anticipated to be contaminated or affect surface waters.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide
narrative discussion of study/data source applicability.
If all answers to rows 1 - 4 are "Yes" a full infiltration design is potentially feasible. The
feasibility screening category is Full Infiltration
Part I
Result* If any answer from row 1-4 is "No", infiltration may be possible to some extent but No Full
would not generally be feasible or desirable to achieve a "full infiltration" design.
Proceed to Part 2
*To be completed using gathered site information and best professional judgment considering the definition of MEP in
the MS4 Permit. Additional testing and/or studies may be required by City Engineer to substantiate findings.
C-12
I
-
1ii L IJ
Pi i 2 -1 'amal I ntii[tac1uI I ?\u 111cdL1iUui1 I eabiiit Lr1llug (riLIIa
Would infiltration of water in an y appreciable amount he pbvsicall\ feasible without any negative
consequences that cannot be reasonable mitigated?
Criteria Screening Question Yes No
Do soil and geologic conditions allow for infiltration in any appreciable rate or
5 volume? The response to this Screening Question shall be based on a
comprehensive evaluation of the factors presented in Appendix C.2 and
Appendix D.
Provide basis: According to Appendix C the lower limit of partial infiltration is 0.05 inches/hour. The average of
the rates determined by testing exceed this amount, therefore partial infiltration is possible.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide
narrative discussion of study/data source applicability and why it was not feasible to mitigate low
infiltration rates.
Can Infiltration in any appreciable quantity be allowed without increasing risk
of geotechnical hazards (slope stability, groundwater mounding, utilities, or
6 other factors) that cannot be mitigated to an acceptable level? The response to X
this Screening Question shall be based on a comprehensive evaluation of the
factors presented in Appendix C.2.
Provide basis: Provided the basins are constructed in the areas with adequate set back from proposed structural
improvements, risk of geotechnical hazards will not be significantly increased.
Lining the sides of the BMP's with impermeable geofabric liner is recommended to reduce lateral
migration of infiltrate. The lining should extend to the maximum depth of utility trenches and
foundation excavations within 100 feet of the proposed basin.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide
narrative discussion of study/data source applicability and why it was not feasible to mitigate low
infiltration rates.
C-13
S
Lriva Screening Question Yes No
Can Infiltration in any appreciable quantity be allowed without posing
significant risk for groundwater related concerns (shallow water table, storm
7 water pollutants or other factors)? The response to this Screening Question X
shall be based on a comprehensive evaluation of the factors presented in
Appendix C.3.
Provide basis: Based on site explorations and knowledge of the site area, groundwater is anticipated to be deeper
than at least 10 feet below the bottom of the planned basin bottoms. Infiltration at the site is not
anticipated to increase the risk of groundwater contamination. According to Geotracker online (a
State of California on line resource for listings of regulated contaminated sites), there are no open
LUST cases in the site area that could impact the site. The proposed development is not industrial
and capture of surface waters is not anticipated to increase the risk of groundwater contamination.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide
narrative discussion of study/data source applicability and why it was not feasible to mitigate low
infiltration rates.
Can infiltration be allowed without violating downstream water rights? The
8 response to this Screening Question shall be based on a comprehensive x
evaluation of the factors presented in Appendix C.3.
Provide basis: Infiltration at the site is not anticipated to cause potential water balance issues and not anticipated
to change the seasonality of ephemeral streams. There are no ephemeral streams in the Site area.
Site discharge is not anticipated to be contaminated or affect surface waters.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide
narrative discussion of study/data source applicability and why it was not feasible to mitigate low
infiltration rates.
If all answers from row 1-4 are yes then partial infiltration design is potentially feasible.
Part 2 The feasibility screening category is Partial Infiltration. Partial Result* If any answer from row 5-8 is no, then infiltration of any volume is considered to be
infeasible within the drainage area. The feasibility screening category is No Infiltration.
*To be completed using gathered site information and best professional judgment considering the definition of MEP in
the MS4 Permit. Additional testing and/or studies may be required by City Engineer to substantiate findings
C-14