HomeMy WebLinkAboutCT 15-09; QUARRY CREEK PA R2; FINAL REPORT OF TESING & OBSERVATION SERVICES; 2017-05-05orI-o9
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FINAL REPORT OF TESTING AND
OBSERVATION SERVICES PERFORMED
DURING SITE FINE GRADING
QUARRY CREEK R-2
CARLSBAD, CALIFORNIA
PREPARED FOR
LENNAR MULTIFAMILY COMMUNITIES, LLC
ALISO VIEJO, CALIFORNIA
MAY 5, 2017
PROJECT NO. 07135-42-07
GEOCON
INCORPORATED
G E 0 T E C H N I C A L U ENVIRONMENTAL • MATE R IA IS
Project No. 07135-42-07
May 5, 2017
Lennar Multifamily Communities, LLC
95. Enterprise, Suite 200
Aliso Viejo, California 92656
Attention: Mr. Eric Schwing
Subject: FINAL REPORT OF TESTING AND OBSERVATION
SERVICES PERFORMED DURING SITE FINE GRADING
QUARRY CREEK R-2
CARLSBAD, CALIFORNIA
Dear Mr. Schwing:
In accordance with your request, we have performed compaction testing and observation services
during fine grading for Quarry Creek R-2. We performed our services during the period of April 4,
through 18, 2017. The scope of our services included the following:
Observing the grading operation, including processing the upper surface of the previously
compacted fill and the placement of compacted fill.
Performing in-place density tests in fill placed and compacted at the site.
Performing laboratory tests to aid in evaluating compaction characteristics of various soil
conditions encountered. We also performed laboratory testing on soil samples collected during
grading activities and near finish grade to evaluate expansion characteristics, and where
applicable, water-soluble sulfate content.
Preparing an as-graded geologic map.
Preparing this final report of grading.
The purpose of this report is to document that the grading of, subject project has been performed in
substantial conformance with the recommendations of the project geotechnical report.
GENERAL
The Quarry Creek site is located south of State Route 78 and west of College Boulevard in the city
of Carlsbad, California. Area R-2 is located within the northeastern portion of the overall' Quarry
Creek development (see Vicinity Map, Figure 1). Two-story multi-family buildings will be
constructed on R-2.
6960 Flanders Drive U SanDiego, California 92121-2974 U Telephone 858.558.6900 0 Fax 858.558.6159
Settlement Monuments
0.75
- 0.5
-C
U
C
' 0.25
I
0 -
-0.25
-0.5
-0.75
-1
0 10 20 30 40 50
Time (Days)
-.-SM#1 -a-SM #2 -o-SM#3
SETTLEMENT MONUMENTS
I.
GEOCON
INCORPORATED
GEOTECHNICALU ENVIRONMENTAL U MATERIALS
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121- 2974
PHONE 858 558-6900 - FAX 858 558-6159
RM I AML DSK/GTYPD
QUARRY CREEK
R-2
CARLSBAD, CALIFORNIA
DATE 05-05-2017 1 PROJECT NO. 07135-42-07 1 FIG.3
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CONCRETE SLAB
PAD GRADE
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RETARDERIN- .••..
ACCORDANCE WITH ACI : ... . . .
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WIDTH FOOTING WIDTH*
*SEE REPORT FOR FOUNDATION WIDTH AND DEPTH RECOMMENDATION NO SCALE
I WALL / COLUMN FOOTING DIMENSION DETAIL I
GEOCON
INCORPORATED (70)
GEOTECHNICALU ENVIRONMENTAL U MATERIALS
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121- 2974
PHONE 858 558-6900 - FAX 858 558-6159
RM / AML DSK/GTYPD
QUARRY CREEK
R-2
CARLSBAD, CALIFORNIA
DATE 05-05- 2017 PROJECT NO. 07135-42 -07 1 FIG. 4
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SURFACE CONCRETE
BROWDITCH
RETAINING -
WALL "-- - —
CONCRETE
BROWDITCH
RETAINING —
WALL
2/3 H
PROPOSED
GROUND SURFACE
WATER PROOFING
PER ARCHITECT
DRAINAGE PANEL
(MIRADRAIN 6000
OR EQUIVALENT)
4 DIA. SCHEDULE 40
PERFORATED PVC PIPE
OR TOTAL DRAIN
EXTENDED TO
APPROVED OUTLET
NO SCALE I
WATER PROOFING
PER ARCHITECT
DRAINAGE PANEL
__— (MIRADRAIN 6000
OR EQUIVALENT)
2/3 H
—12-1
3/4' CRUSHED ROCK
- /(1 CU.FT/FT.)
i—FILTER FABRIC PROPOSED ENVELOPE GRADE\ & ( MIRAFI 140N OR
EQUIVALENT
FOOTING1 4" DIA. SCHEDULE 40
I PERFORATED PVC PIPE
OR TOTAL DRAIN
EXTENDED TO
APPROVED OUTLET
NOTE:
DRAIN SHOULD BE UNIFORMLY SLOPED TO GRAVITY OUTLET
OR TO A SUMP WHERE WATER CAN BE REMOVED BY PUMPING
CONCRETE
BROWDITCH 1
PROPOSED
RETAINING WALL
GROUND SURFACE
WATER PROOFING
PER ARCHITECT
2/3 H . IMIRAFI 140N FILTER FABRIC I (OR EQUIVALENT)
OPEN GRADED
:--- 1" MAX. AGGREGATE
GROUND SURFACE
4 DIA. PERFORATED SCHEDULE
40 PVC PIPE EXTENDED TO
APPROVED OUTLET
12/
I TYPICAL RETAINING WALL DRAIN DETAIL I
GEOCON (4 INCORPORATED 0 /
GEOTECHNICAL• ENVIRONMENTAL. MATERIALS
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974
PHONE 858 558-6900 - FAX 858 558-6159
RM I AML DSK/GTYPD
QUARRY CREEK
R-2
CARLSBAD, CALIFORNIA
DATE 05-05-2017 1 PROJECT NO. 07135-42-07 1 FIG. 5
PIottd:05105/2017 925AM I By.ALVtN LADRILLONO I File LeeeteY IPROJECFS\07135-42-07 (R-2)IOETAI1-S\lypiee1 Retaining Wag Oree,ege Deteil (RW1D07A).dwg
TABLE I
GEOCON SUMMARY OF FIELD DENSITY TEST RESULTS
Project Name: Quarry Creek R-2 Project No.: 07135-42-07
Test No.
- - -
Date
MM/DD (
IYY)
Location
Elev.
or
Depth
(feet)
Curve
No.
Re.
>14 "
Rock
(%)
Max.
Dry
Density
(pci)
Opt.
Moist
Content
(%)
Field
Dry
Density
(pci)
Field
Moisture
Content
(%)
Relative
Compaction
(%)
Required
Relative
Compaction
(%)
Pre. No.
1 04/03/17 Bldg 3 113 2 0 119.0 11.6 107.9 11.9 91 90
2 04/03/17 Bldg 114 2 0 119.0 11.6 107.3 12.8 90 90
3 04/03/17 Bldg 114 2 0 119.0 11.6 107.7 12.3 91 90
4 04/04/17 Bldg 114 2 0 119.0 11.6 109.7 14.7 92 90
5 04/04/17 Bldg 11 116 2 0 119.0 11.6 109.2 13.5 92 90
6 04/04/17 Bldg 115 2 0 119.0 11.6 1075 15.2 90 90
7 04/04/17 Bldg 11 116 2 0 119.0 11.6 108.7 11.8 91 90
8 04/05/17 Bldg 114 30 0 130.5 9.6 122.9 12.8 94 90
9 04/05/17 Bldg 116 30 0 130.5 9.6 120.4 13.1 92 90
10 04/05/17 Bldg 115 30 0 130.5 9.6 119.0 13.4 91 90
11 04/06/17 Bldg 113 4 0 126.0 10.4 117.0 11.1 93 90
12 04/06/17 Bldg 114 4 0 126.0 104 117.5 10.8 93 90
13 04/06/17 Bldg 114 4 0 126.0 10.4 115.5 10.5 92 90
14 04/06/17 Bldg 114 4 0 126.0 10.4 116.4 11.3 92 90
15 04/07/17 Bldg 115 4 0 126.0 10.4 114.9 1 12.0 91 90
16 04/07/17 Bldg 115 4 0 126.0 10.4 113.9 13.0 90 90
17 04/07/17 Bldg 115 4 0 126.0 10.4 117.6 10.9 93. 90
FG 18 j 04/10/17 Bldg 116 4 0 126.0 10.4 115.2 11.0 91 90
FG 19 04/10/17 Bldg - 116 4 0 126.0 10.4 116.3 11.3 92 90
FG 20 04/10/17 Bldg 117 2 0 119.0 11.6 109.7 11.8 92 90
FG 21 04/10/17 Bldg 5 116 2 0 119.0 11.6 108.9 13.0 92 90
FG 22 04/10/17 Bldg 11 118 2 0 119.0 11.6 111.1 11.8 93 90
FG 23 04/10/17 Bldg 11 117 2 0 119.0 11.6 108.9 12.5 92 90
FG 24 04/10/17 Bldg 113 4 0 126.0 1 10.4 115.2 10.4 91 90
FG 25 04/10/17 Bldg 10 115 4 0 126.0 10.4 113.9 12.1 90 90
FG 26 04/10/17 Bldg 112 2 0 119.0 11.6 111.8 11.8 94 90
FG 27 04/10/17 Bldg 111 2 0 119.0 11.6 112.0 11.3 94 90
FG 28 04/11/17 Bldg 113 2 0 119.0 11.6 112.6 11.8 95 90
FG 29 04/11/17 Bldg 112 2 0 119.0 11.6 110.4 11.9 93 90
FG 30= 04/11/17
_____
Bldg ______
112 4 0 126.0 10.4 121.7 11.0 97 90
()GEOCON - -
Project Name: Quarry Creek R-2
TABLE I
SUMMARY OF FIELD DENSITY TEST RESULTS
Project No.: 07135-42-07
Test No.
-
Date
(MM/DD
iYy)
Location
Elev.
or
Depth
(feet)
Curve
No.
>' Rock
°
Max..
Dry
Density
(pci)
Opt.
Moist
Content
(%)
Field
Dry
Density
(pci)
Field
Moisture
Content
(%)
Relative
Compaction
(%)
Required
Relative
Compaction
(%)
Pre.
-
No.
-
Re.
FG 31 - 04/11/17 Bldg 113 4 0 126.0 10.4 118.4 10.6 94 90
32 04/12/17 Bldg 1 112 4 0 126.0 10.4 116.4 12.4 92 90
33 - 04/12/17 Bldg 1 113 4 0 126.0 10.4 116.2 12.1 92 90
34 04/12/17 Bldg 1 114 4 0 126.0 10.4 116.9 11.9 93 90
- 35 - 04/12/17 Bldg 1 114 4 0 126.0 10.4 116.3 11.2 92 90
- 36 - 04/13/17 Bldg 1 114 4 0 126.0 10.4 113.6 12.6 90 90
- 37 - 04/13/17 Bldg 1 114 4 0 126.0 10.4 116.4 12.3 92 90
- 38 - 04/13/17 Bldg 12 116 4 0 126.0 10.4 1I5A0 10.8 91 90
- 39 - 04/13/17 Bldg 12 116 4 0 126.0 10.4 117.5 10.7 93 90
- 40 - 04/13/17 Bldg 12 117 4 0 126.0 10.4 117.3 10.4 93 90
- 41 - 04/14/17 Bldg 12 117 4 0 126.0 10.4 113.9 13.0 90 90
FG 42 - 04/14/17 Bldg 116 4 0 126.0 10.4 116.1 11.6 92 90
FG 43 04/14/17 Bldg 1 115 4 0 126.0 10.4 115.6 11.2 92 90
- 44 04/17/17 Pool 109 4 0 126.0 10.4 113.9 12.9 90 90
- 45 - 04/17/17 Pool 110 4 0 126.0 10.4 118.1 10.7 94 90
- 46 - 04/17/17 Pool 110 4 0 126.0 10.4 116.4 13.4 92 90
47 04/17/17 Pool 111 4 0 126.0 10.4 116.2 13.1 92 90
48 04/17/17 Pool 111 4 0 126.0 10.4 115.1 12.4 91 90
-
49 04/17/17 Pool 111 4 0 126.0 10.4 115.6 13.2 92 90
FG 50 04/18/17 Bldg 12 118 4 0 126.0 10.4 117.2 11.2 93 90
FG 51 - 04/18/17 Bldg 12 118 4 0 126.0 10.4 114.8 12.3 91 90
FG 52 - 04/18/17 Pool 112 4 0 126.0 10.4. 114.4 12.2 91 90
FG 53 - 04/18/17 Bldg 13
_ ____
117 4 0 126.0 10.4 116.0 13.5 92 90
FG 54 04/18/17
_____
Bldg 13
_____
117 4 0 126.0 10.4 115.4 13.1 92 90
<10~) GEOCON
TABLE I
EXPLANATION OF CODED TERMS
TEST NO. PREFIX
AC Asphalt Concrete IT Irrigation Trench SG Subgrade
AD Area Drain iT Joint Trench SL Sewer Lateral
B Base M Moisture Test SM Sewer Main
CG Curb/Gutter MG Minor Grading SR Slope Repair
DW Driveway MSE Mechanically Stabilized Earth Wall ST Slope Test
ET Electrical Trench PT Plumbing Trench SW Sidewalk
ETB Exploratory Trench RG Regrade SZ Slope Zone
FB Footing Backfill RWL Reclaimed Water Lateral UT Utility Trench
FG Finish Grade RWM Reclaimed Water Main WB Wall Backfill
FS Fire Service SBT Subdrain Trench WL Water Lateral
GT Gas Trench SD Storm Drain WM Water Main
TEST NO. RE.
A, B, C, .. Retest of previous density test failure following additional moisture conditioning or recompaction
R Fill in area of density test was removed during construction operations
ELEVATION OR DEPTH
Corresponds to the elevation or the depth, in feet, of the in-place density/moisture content test. The value has been rounded to the
nearest whole foot
CURVE NO.
Corresponds to the curve numbers presented in the summary of the laboratory maximum dry density and optimum moisture content test
results. The field representative selected the curve no. based on the laboratory test results and field observations
>%" ROCK - ROCK CORRECTION
TABLE II
SUMMARY OF LABORATORY MAXIMUM DRY DENSITY AND
OPTIMUM MOISTURE CONTENT TEST RESULTS
ASTM D 1557
Sample Maximum Optimum
No Description Dry Density Moisture Content
(pci) (% dry weight)
2 Dark olive-brown to gray, Sandy CLAY 119.0 11.6
4 Light brown to olive, Silty, fine to coarse SAND 1 126.0 1 10.4
30 Dark brown, Clayey, fme to coarse SAND with little gravel 1 130.5 1 9.6
TABLE III
SUMMARY OF LABORATORY EXPANSION INDEX TEST RESULTS
ASTM D 4829
Sample
No. Representative Lot
Moisture Content (°"°) Dry
Density
(pci)
Expansion
Index
ASTM
Classification
(per 2013 CBC)
Before
Test
After
Test
El-2 Buildings 9.7 18.4 111.0 43 Low
El-3 Building 9.9 20.0 110.7 48 Low
El-4 Buildings 5 and 11 10.0 20.2 109.6 59 Medium
EI-5 Buildings 6, 7, 9 and 10 9.8 18.9 110.0 41 Low
EI-6 Buildings 2 and 8 9.7 20.0 109.9 51 Medium
El-7 Building 13 9.9 18.4 109.2 36 Low
EI-8 1 Rec Building and 12 10.2 20.4 107.9 49 Low
TABLE IV
SUMMARY OF LABORATORY WATER-SOLUBLE SULFATE TEST RESULTS
CALIFORNIA TEST NO. 417
Sample No. Representative Lot Water-Soluble Sulfate (%) Sulfate Exposure
El-2 Buildings 3 0.052 Not Applicable (SO)
El-3 Building 4 0.045 Not Applicable (SO)
EI4 Buildings 5 and 11 0.043 Not Applicable (SO)
El-S Buildings 6, 7,9 and 10 0.082 Not Applicable (SO)
EI-6 Buildings 2 and 8 0.041 Not Applicable (SO)
E1-7 Building 13 0.018 Not Applicable (SO)
E1-8 Rec Building and 12 0.083 Not Applicable (SO)
Project No. 07135-42-07 May 5, 2017
TABLE V
SUMMARY OF AS-GRADED BUILDING PAD CONDITIONS
AND RECOMMENDED FOUNDATION CATEGORY FOR
QUARRY CREEK, R-2
Lot No. Pad Condition
Approximate
Maximum
Depth of Fill
(feet)
Approximate
Depth of Fill
Differential
(feet)
Expansion
Index
Recommended
Foundation
C a egory
1 Fill! Alluvium 31 10 49 III
2 Fill! Alluvium 26 4 51 III
3 Undercut Fill! Alluvium 26 22 43 Ill
4 Undercut Fill! Alluvium 26 23 48 III
5 Undercut Fill 4 1 59 II
6 Fill/Alluvium 23 8 41 III
7 Fill! Alluvium 22 0 41 III
8 Fill! Alluvium 23 2 51 III
9 Fill/ Alluvium 23 0 41 III
10 Fill/ Alluvium 25 0 41 III
11 Undercut Fill 4 1 59 II
12 Undercut Fill 20 17 49 II
13 Fill! Alluvium 27 11 36 111
Project No. 07135-42-07 May 5, 2017
LB3 Enterprises Inborporated performed the grading. The plans are prepared by SB&O, Incorporated
titled Rough Grading Plans for Quarry Creek Planning Area R-2, with the City approval date
February 3, 2017 (Project No. SDP 15-22, Drawing No. 484-5K). Geocon Incorporated prepared the
project geotechnical report titled Update Geotechnical Report, Quarry Creek R-2, Carlsbad,
California, dated April 11, 2016 (Project No. 0713 5-42-07). The following are additional geotechnical
reports pertinent to the project:
Final Report of Testing and Observation Services During Site Grading, Quarry Creek,
Carlsbad, California, prepared by Geocon Incorporated, dated April 4, 2013 (Project
No. 07135-42-02).
Final Report of Testing and Observation Services • Performed During Site Grading, Quarry
Creek R-2, Carlsbad California, prepared by Geocon Incorporated, dated October 31, 2016
(Project No. 0713 5-42-05).
We used an AutoCAD file of the grading plans provided by SB&O as the base map to present as-
graded geology and the approximate locations of in-place density tests (Figures 2, map pocket). The
map depicts slopes, building pads, streets and, current and previous ground topography.
References to elevations and locations herein are based on surveyors' or grade checkers' stakes in the
field, elevation shots taken with a Global Positioning System (GPS). unit by the grading contractor,
and/or interpolation from the referenced grading plan. Geocon Incorporated does not provide
surveying services and, therefore, expresses no opinion regarding the accuracy of the as-graded
elevations or surface geometry with respect to the approved grading plans or proper surface drainage.
GRADING
Reclamation Grading
Portions of the Quarry Creek property have undergone many years of mining, crushing, and screening
to produce commercial aggregate products. The majority of previous mining activity occurred in the
eastern and southern portions of the overall Quarry Creek site. Mining resulted in undocumented fills
and some compacted fill across the former mined areas.
Reclamation grading of the previously mined area commenced in July 2011 and was completed in
December 2012. During reclamation grading, undocumented fills were removed and replaced as
compacted fill. Drop structures, levees, and rock revetment slopes were constructed along and in
Buena Vista Creek drainage. Reclamation grading resulted in removal of undocumented fill and
replacement with compacted fill. A summary of observations and compaction tests performed during
reclamation grading is contained in our April 2013 as-graded report.
Project No. 07135-42-07 -2- May 5, 2017
During reclamation grading complete removal of undocumented fill and alluvium could not be
performed in the southern portion of the lot due to groundwater. The area where undocumented fill
and alluvium was left below the groundwater is shown on the geologic map (Figure 2). After the
completion of reclamation grading, a settlement monument was installed and monitored by
periodically for a period of 48 days. Monitoring indicated settlement of the undocumented fill and
alluvium as a result of the approximately 20 to 25 feet of fill placed over the surficial soils was
essentially complete. The table below shows the survey results over the monitoring period.
TABLE I
SUMMARY OF SETTLEMENT MONITORING
AT THE COMPLETION OF RECLAMATION GRADING
Monument Number Date of Reading Elevation (feet) Change from Initial
Reading (feet)
1
10/19/12 107.70 --
11/2/12 107.68 -0.02
11/19/12 107.68 -0.02
- 12/5/12 107.70 0
7/23/15 107.74 +0.04
Prior to the start of grading associated with the Quarry Creek project, the monument was resurveyed.
The survey information is included on Table 1 and indicated that no settlement had occurred over a
period of almost 3 years.
Previous Mass Grading
Mass grading was conducted between July 7, 2015, and October 14, 2016, and consisted of cuts from
existing reclamation grades of approximately 30 feet and fills up to 12 feet. The surface of existing
compacted fill was scarified, moisture conditioned, and recompacted prior to receiving additional fill.
Fill soils were then placed and compacted in layers until design elevations were attained. Fills were
placed in lifts no thicker than would allow for adequate bonding and compaction. Grading generally
resulted in an approximately three-foot-thick soil cap that generally consists of very low to medium
expansive materials. In general, fill materials placed during grading consist of clayey to silty sand and
silty to sandy clay.
Grading for this phase resulted in approximately 4 to 10 feet of fill being placed within the southern
portion of R-2, where alluvium and saturated undocumented fill were left in place during reclamation
grading. In this area, an additional 5 feet of surcharge fill was placed above finish grade. Three
settlement monuments were installed and a settlement monitoring program was initiated. The
monuments were surveyed on a weekly basis over a period of 44 days. The program was halted when
Project No. 07135-42-07 -3- May 5, 2017
no significant settlement was detected. The settlement monitoring data is presented graphically on
Figure 3.
During the excavation for the cut slope located along north side of the property, undocumented fill
associated with the construction of the existing Haymar Drive was exposed. The removal of the
undocumented fill was limited due to the presence of the existing road and improvements. In the
northeast portion of the slope partial removal was performed and a drained buttress fill was
constructed. The apprOximate limits of the undocumented fill left in-place are shown on the As-
Graded Geologic Map (Figure 2).
A bedding plane shear (BPS) and interbedded claystone and sandstone were also encountered in the
northern slope cut. A drained buttress fill was constructed for the slope. The location of the heel drain
was surveyed by the project civil engineer and plotted on our As-Graded Geologic Map (Figure 2).
The limits of the buttress fill are shown on Figure 2.
Due to the presence of an electric power pole that could not be removed at the time of mass grading
operation, a section of the northern slope was not completed. The pole was recently removed and
grading of the slope, including the buttress fill was completed.
Oversized rocks (material > 6 inches) were placed at least three feet below design finish grade in
graded areas. Rock greater than 12 inches exist within the compacted fill material placed during
previous phases of grading. Oversize rock was spread out within the compacted fill areas such that soil
around the oversize rock could be compacted by the grading equipment. Although particular attention
was given to restricting oversize material placement to the criteria described above, some oversize
chunks could be present in the upper portions of the fill areas. Oversize rocks may also exist within the
formational materials at or near the ground surface.
Recent Grading
Grading covered under this report consisted of cut and fill of less than 5 feet to fine grade the proposed
building pads. The existing fill and formational materials were scarified, moisture conditioned and
compacted prior to receiving additional fill. The cut portion of the building pads were undercut
approximately 3 feet and replaced with properly compacted fill.
During the grading operation, we observed compaction procedures and performed in-place density
tests to evaluate the dry density and moisture content of the fill material. We performed in-place
density tests in general conformance with ASTM D 6938, Standard Test Method for In-Place Density
and Moisture Content of Soil and Soil-Aggregate by Nuclear Methods. A summary of in-place density
and moisture content tests are presented on Table I.
Project No. 07135-42-07 -4 - May 5, 2017
Where fill soil contained rock larger than 3/4-inch, a correction was made to the laboratory maximum
dry density and optimum moisture content using methods suggested by AASHTO T224. The values of
maximum dry density and optimum moisture content presented on Table I reflect these corrections.
In general, in-place density test results indicate fill soils have a dry density of at least 90 percent of the
laboratory maximum dry density at or slightly above optimum moisture content at the locations tested.
The approximate locations of in-place density tests taken during grading specific to R-2 are shown on
Figure 2.
We performed laboratory tests on samples of soil used for fill to evaluate moisture-density
relationships, optimum moisture content and maximum dry density (ASTM D 1557). Additionally, we
performed laboratory tests on soil samples collected at various stages of grading and near finish grade
(soil fill cap) to evaluate expansion potential (ASTM D 4829) and where applicable, water-soluble
sulfate content (California Test No. 417). Results of the laboratory tests are summarized on Tables II
through IV.
Slopes
The fill slopes constructed during previous grading phases have an approximate inclination of 2:1 and
1.5:1 (horizontal: vertical) or flatter, with maximum height of approximately 32 feet. The fill slope
located along the northern and northeastern property margins is a drained buttress fill constructed to
intercept a Bedding Plane Shear encountered within the formational materials and also to stabilize
undocumented fill left in place in this area. The heel drain associated with the buttress 1111 is
currently connected to two raisers and needs to be. connected to the permanent storm drain
system once it is installed.
Fill slopes associated with the basins along the southern portion of the lot were constructed during
recent grading covered by this report. Fill slopes that extend into the adjacent Buena Vista Creek
drainage were constructed during previous reclamation and mass grading. The outer approximately 15
feet of fill slopes were constructed with granular soil and were either over-filled and cut back or were
track-walked with a bulldozer during gading in substantial conformance with the recommendations of
the project geotechnical report. The project slopes (recently and previously graded) have a calculated
factor of safety of at least 1.5 under static conditions with respect to both deep-seated failure and
shallow sloughing conditions.
All slopes should be planted, drained, and maintained to reduce erosion. Slope irrigation should be
kept to a minimum to just support the vegetative cover. Surface drainage should not be allowed to
flow over the tops of slopes.
Project No. 07135-42-07 -5- May 5, 2017
Finish Grade Soil Conditions
Laboratory test results and field observations indicate that the prevailing soil conditions within the upper
approximately three feet of finish grade have an expansion potential (El) of 90 or less and considered as
low to medium expansive as defined by ASTM D 4829. These soils are classified as expansive (El >20)
as defined by 2013 California Building Code (CBC) Section 1803.5.3. Table 3 presents soil classifications
based on the expansion index per ASTM D 4829 and the CBC. Table HI at the end of this report presents
a summary of expansion index test results for the prevailing subgrade soils at Quarry Creek, Area R-2.
TABLE 3
SOIL CLASSIFICATION BASED ON EXPANSION INDEX
ASTM D 4829
Expansion Index (El) ASTM
Expansion Classification
CBC
Expansion Classification
0-20 Very Low Non-Expansive
21-50 Low
Expansive
Very High
51-90 Medium
91-130 High
Greater Than 130
We performed laboratory water-soluble sulfate testing on samples obtained for expansion testing to
assess whether the soil contains sulfate concentrations high enough to damage normal Portland cement
concrete. Results from the laboratory water-soluble sulfate content tests are presented in Table IV at
the end of this report and indicate that the on-site materials at the locations tested possess "Not
Applicable" sulfate exposure and "SO" sulfate exposure class to concrete structures as defined by 2013
CBC Section 1904 and ACI 318-08 Sections 4.2 and 4.3. Table 4 presents a summary of concrete
requirements set forth by 2013 CBC Section 1904 and ACT 318. The presence of water-soluble
sulfates is not a visually discernible characteristic; therefore, other soil samples from the site could
yield different concentrations. Additionally, over time landscaping activities (i.e., addition of
fertilizers and other soil nutrients) may affect the concentration.
Project No. 07135-42-07 -6- May 5, 2017
TABLE 4
REQUIREMENTS FOR CONCRETE EXPOSED TO
SULFATE-CONTAINING SOLUTIONS
Water-Solub Maximumle Minimum Sulfate Exposure Sulfate Percent Cement Water to
. Compressive Exposure Class by Weight Type Cement Ratio Strength (psi) by Weight
Not Applicable SO 0.00-0.10 -- -- 2,500
Moderate Si 0.10-0.20 II 0.50 4,000
Severe S2 0.20-2.00 V 0.45 4,500
Very Severe S3 >2.00 V+Pozzolan or Slag 0.45 4,500
Geocon Incorporated does not practice in the field of corrosion engineering. Therefore, if
improvements that could be susceptible to corrosion are planned, further evaluation by a corrosion
engineer should be performed.
SOIL AND GEOLOGIC CONDITIONS
In general, the soil and geologic conditions encountered during grading were found to be similar to
those described in the referenced project geotechnical report. The site is underlain by compacted fill
soils (Qcf) overlying undocumented fill (Qudf), alluvium (Qal) and the Santiago Formation (Ts).
The as-graded geologic map (Figure 2) has been annotated to show a general representation of the as-
graded geologic conditions observed during grading. Geologic contacts should be considered
approximate.
CONCLUSIONS AND RECOMMENDATIONS
1.0 General
1.1 Based on observations and test results, it is the opinion of Geocon Incorporated that grading,
which is the subject of this report, has been performed in substantial conformance with the
recommendations of the referenced project geotechnical repOrts. Soil and geologic
conditions encountered during grading that differ from those anticipated by the project
geotechnical reports are not uncommon. Where such conditions required a significant
modification to the recommendations of the project geotechnical reports, they have been
described herein.
1.2 No soil or geologic conditions were observed during grading that would preclude the
continued development of the property as planned. Based on laboratory test results and field
Project No. 07135-42-07 - 7 - May 5, 2017
observations, it is our opinion that the fill soils placed during grading have been compacted
to at least 90 percent relative compaction.
1.3 References to fill thickness or capping of pads are approximate and may be affected by
subsequent fine grading to achieve proper surface drainage.
20 Future Grading
2.1 Any additional grading performed at the site should be accomplished in conjunction with
our observation and compaction testing services. Geocon Incorporated should review
grading plans for any future grading prior to finalizing. All trench and wall backfill should
be compacted to .a dry density of at least 90 percent of the laboratory maximum dry density
near or to slightly above optimum moisture content. This office should be notified at least
48 hours prior to commencing additional grading or backfill operations.
3.0 Seismic Design Criteria
3.1 We used the computer program U.S. Seismic Design Maps, provided by the USGS.
Table 3.1 summarizes site-specific seismic design criteria including spectral response
accelerations in accordance with 2013 California Building Code (CBC; Based on the 2012
IntrnationaI Building Code [IBC] and ASCE 7-10), Chapter 16 Structural Design,
Section 1613 Earthquake Loads. The short spectral response uses a period of 0.2 second.
The structures should be designed using a Site Class D. We evaluated the Site Class based
on the discussion in Section 1613.3.2 of the 2013 CBC and Table 20.3-1 of ASCE 7-10. The
values presented in Table 3.1 are for the risk-targeted maximum considered earthquake
(MCER).
Project No. 07135-42-07 -8- May 5, 2017
TABLE 3.1
2013 CBC SEISMIC DESIGN PARAMETERS
Parameter Value 2013 CBC
Reference
Site Class D Table 1613.5.2
Spectral Response —Class B (0.2 see), Ss 1.064 g Figure 1613.5(3)
Spectral Response - Class B (1 see), Si 0.412 g Figure 1613.5(4)
Site Coefficient, Fa 1.074 Table 1613.5.3(1)
Site Coefficient, F 1.588 Table 1613.5.3(2)
Maximum Considered Earthquake 1143 . g Section 1613.5.3
Spectral Response Acceleration (0.2 see), SMS (Eqn 16-36)
Maximum Considered Earthquake 0 655 . g Section 16 13.5.3
Spectral Response Acceleration (1 see), SMI (Eqn 16-37)
5% Damped Design
. 0.7629 Section 16 13.5.4
Spectral Response Acceleration (0.2 see), SOS (Eqn 16-38)
5% Damped Design 0436 g Section 1613.5.4
Spectral Response Acceleration (1 see), (Eqn 16-39)
3.2 Table 3.2 presents additional seismic design parameters for projects located in Seismic
Design Categories of C through D inaccordance with ASCE 7-10 for the mapped maximum
considered geometric mean (MCEG).
TABLE 3.2
2013 CBC SEISMIC DESIGN PARAMETERS
Parameter Value ASCE 7-10 Reference
Mapped MCEG Peak Ground Acceleration, PGA 0.408g Figure 22-7
Site Coefficient, FPGA 1.092 Table 11.8-1
Site Class Modified MCEG
Peak Ground Acceleration, PGAM 0.445g Section 11.8.3 (Eqn 11.8-1)
3.3 Conformance to the criteria presented in Tables 3.1 and 3.2 for seismic design does not
constitute any guarantee or assurance that significant structural damage or ground failure will
not occur in the event of a maximum level earthquake. The primary goal of seismic design is to
protect life and not to avoid all damage, since such design may be economically prohibitive.
4.0 Foundation Recommendations
4.1 The foundation recommendations that follow are for one- to four-story residential structures
and are separated into categories dependent on the thickness and geometry of the underlying
Project No. 07135-42-07 -9 - May 5, 2017
fill soils, as well as the expansion index of the prevailing subgrade soils of a particular
building pad (see Table 4.1). The foundation category for each lot is provided on Table V.
TABLE 4.1
FOUNDATION CATEGORY CRITERIA
Foundation Maximum Fill Differential Fill Expansion
Category Thickness, T (feet) Thickness, D (feet) Index (El)
I T<20 -- EI<50
II 20<1<50 10<D<20 50<EI<90
T>50 or underlain III by alluvium D>20 90<E1<130
4.2 Table 4.2 presents minimum foundation and interior concrete slab design criteria for
conventional foundation systems. A typical footing dimension detail is provided on
Figure 4.
TABLE 4.2
CONVENTIONAL FOUNDATION RECOMMENDATIONS BY CATEGORY
Foundation Minimum Footing
Embedment Depth Continuous Footing Interior Slab
Category (inches) Reinforcement Reinforcement
I 12 Two No. 4 bars, 6x6-1 0/10 welded wire
one top and one bottom mesh at slab mid-point
II 18 Four No. 4 bars, No. 3 bars at 24 inches
two top and two bottom on center, both directions
III 24 Four No. 5 bars, No. 3 bars at 18 inches
two top and two bottom on center, both directions
4.3 The embedment depths presented in Table 4.2 should be measured from the lowest adjacent
pad grade for both interior and exterior footings. The conventional foundations should have
a minimum width of 12 inches and 24 inches for continuous and isolated footings,
respectively.
4.4 The concrete slab-on-grade should be a minimum of 4 inches thick for Foundation
Categories I and II and 5 inches thick for Foundation Category III.
4.5 Slabs that may receive moisture-sensitive floor coverings or may be used to store moisture-
sensitive materials should be underlain by a vapor retarder. The vapor retarder design should
be consistent with the guidelines presented in the American Concrete Institute's (ACI) Guide
Project No. 07135-42-07 - 10 May 5, 2017
for Concrete Slabs that Receive Moisture-Sensitive Flooring Materials (ACI 302.2R-06). In
addition, the membrane should be installed in accordance with manufacturer's
recommendations and ASTM requirements, and in a manner that prevents puncture. The
project architect or developer should specify the vapor retarder based on the type of floor
covering that will be installed and if the structure will possess a humidity controlled
environment.
4.6 The project foundation engineer, architect, and/or developer should determine the thickness
of bedding sand below the slab. In general, 3 to 4 inches of sand bedding is typically used.
Geocon should be contacted to provide recommendations if the bedding sand is thicker than
6 inches.
4.7 The foundation design engineer should provide appropriate concrete mix design criteria and
curing measures to assure proper curing of the slab by reducing the potential for rapid
moisture loss and subsequent cracking and/or slab curl. The foundation design engineer
should specify the concrete mix design and proper curing methods on the foundation plan. It is
critical that the foundation contractor understands and follows the recommendations presented
on the foundation plan.
4.8 As an alternative to the conventional foundation recommendations, consideration should be
given to the use of post-tensioned concrete slab and foundation systems for the support of the
proposed structures. The 2013 CBC has updated the design requirements for post-tensioned
foundation systems. The post-tensioned systems should be designed by a structural engineer
experienced in post-tensioned slab design and design criteria of the Post-Tensioning Institute
(PTI), Third Edition, as required by the 2013 CBC (Section 1805.8). Although this procedure
was developed for expansive soil conditions, we understand it can also be used to reduce the
potential for foundation distress due to differential fill settlement. The post-tensioned design
should incorporate the geotechnical parameters presented in Table 4.3 for the particular
Foundation Category designated. The parameters presented in Table 4.3 are based on the
guidelines presented in the PTI, Third Edition design manual.
Project No. 07135-42-07 -11- May 5, 2017
TABLE 4.3
POST-TENSIONED FOUNDATION SYSTEM DESIGN PARAMETERS
Post-Tensioning Institute (PT!)
Third Edition Design Parameters
Foundation Category
1 11 111
Thornthwaite Index -20 -20 -20
Equilibrium Suction 3.9 3.9 3.9
Edge Lift Moisture Variation Distance, em (feet) 5.3 5.1 4.9
Edge Lift, yM(inches) 0.61 1.10 1.58
Center Lift Moisture Variation Distance, em (feet) 9.0 9.0 9.0
Center Lift, yM(inches) 0.30 0.47 0.66
4.9 If the structural engineer proposes a post-tensioned foundation design method other than the
2013 CBC:
The criteria presented in Table 4.3 are still applicable.
Interior stiffener beams should be used for Foundation Categories II and III.
The width of the perimeter foundations should be at least 12 inches.
The perimeter footing embedment depths should be at least 12 in 18 inches and
24 inches for foundation categories I, II, and III, respectively. The embedment
depths should be measured from the lowest adjacent pad grade.
4.10 The foundations for the post-tensioned slabs should be embedded in accordance with the
recommendations of the structural engineer. If a post-tensioned mat foundation system is
planned, the slab should possess a thickened edge with a minimum width of 12 inches and
extend at least 6 inches below the clean sand or crushed rock layer.
4.11 Our experience indicates post-tensioned slabs are susceptible to excessive edge lift,
regardless of the underlying soil conditions. Placing reinforcing steel at the bottom of the
perimeter footings and the interior stiffener beams may mitigate this potential. Current PTI
design procedures primarily address the potential center lift of slabs but, because of the
placement of the reinforcing tendons in the top of the slab, the resulting eccentricity after
tensioning reduces the ability of the system to mitigate edge lift. The structural engineer
should design the foundation system to reduce the potential of edge lift occurring for the
proposed structures.
4.12 During the construction of the post-tension foundation system, the concrete should be placed
monolithically. Under no circumstances should cold joints form between the footings/grade
beams and the slab during the construction of the post-tension foundation system.
Project No. 07135-42-07 -12- May 5, 2017
4.13 Category I, II, or III foundations may be designed for an allowable soil bearing pressure of
2,000 pounds per square foot (ps (dead plus live load). This bearing pressure may be
increased by one-third for transient loads due to wind or seismic forces. The estimated
maximum total and differential settlement for the planned structures due to foundation loads
is 1 inch and V2 inch, respectively. Differential settlement is estimated to occur over a span
of 40 feet.
4.14 We expect primary settlement of existing fills is essentially complete. However, we estimate
that additional settlement as a result of hydro-consolidation to be approximately 0.2 to
0.3 percent of the total fill thickness. We expect hydro-consolidation to occur over a 20 year
or more duration. We estimate a total fill settlement as a result of hydro-consolidation to be
1 inch or less in areas where compacted fill exists.
4.15 Foundations will need to be designed to accommodate estimated total and differential fill
settlement from both building loading and hydroconsolidation. In addition, building pads on
Lot R-2 where alluvium was left in-place should incorporate the estimated liquefaction
differential settlement of 1/2-inch across the building width.
4.16 Isolated footings, including PT foundation systems where footings are not reinforced with
PT cables, should have the minimum embedment depth and width recommended for
conventional foundations (see Sections 4.2 through 4.5) for a particular foundation category.
The use of isolated footings, which are located beyond the perimeter of the building and
support structural elements connected to the building, are not recommended for Category
III. Where this condition cannot be avoided, the isolated footings should be connected to the
building foundation system with grade beams.
4.17 For Foundation Category III, consideration should be given to using interior stiffening
beams and connecting isolated footings and/or increasing the slab thickness. In addition,
consideration should be given to connecting patio slabs, which exceed five feet in width, to
the building foundation to reduce the potential for future separation to occur.
4.18 Special subgrade presaturation is not deemed necessary prior to placing concrete; however,
the exposed foundation- and slab-subgrade soil should be moisture conditioned, as
necessary, to maintain a moist condition as would be appropriate in any such concrete
placement.
4.19 Where buildings or other improvements are planned near the top of a slope steeper than 3:1
(horizontal: vertical), special foundations and/or design considerations are recommended due
to the tendency for lateral soil movement to occur.
Project No. 07135-42-07 -13- May 5, 2017
For fill slopes less than 20 feet high or cut slopes regardless of height, footings
should be deepened such that the bottom outside edge of the footing is at least 7 feet
horizontally, from the face of the slope.
For fill slopes greater than 20 feet high, foundations should be extended to a depth
where the minimum horizontal distance is equal to 1-1/3 (where H equals the vertical
distance from the top of the fill slope to the base of the fill soil) with a minimum of
7 feet but need not exceed 40 feet. The horizontal distance is measured from the
outer, deepest edge of the footing to the face of the slope. A post-tensioned slab and
foundation system or mat foundation system can be used to help reduce potential
foundation distress associated with slope creep and lateral fill extension. Specific
design parameters or recommendations for either of these alternatives can be
provided once the building location and fill slope geometry have been determined.
If swimming pools are planned, Geocon Incorporated should be contacted for a
review of specific site conditions.
Swimming pools located within 7 feet of the top of cut or fill slopes are not
recommended. Where such a condition cannot be avoided, the portion of the
swimming pool wall within 7 feet of the slope face be designed assuming that the
adjacent soil provides no lateral support. This recommendation applies to fill
slopes up to 30 feet in height, and cut slopes regardless of height. For swimming
pools located near the top of fill slopes greater than 30 feet in height, additional
recommendations may be required and Geocon Incorporated should be contacted
for a review of specific site conditions.
Although other improvements that are relatively rigid or brittle, such as concrete
flatwork or masonry walls, may experience some distress if located near the top of a
slope, it is generally not economical to mitigate this potential. It may be possible,
however, to incorporate design measures that would permit some lateral soil
movement without causing extensive distress. Geocon Incorporated should be
consulted for specific recommendations.
4.20 The exterior flatwork recommendations provided herein assumes that the near surface soils
are very low to low expansive (El < 50). Exterior slabs not subjected to vehicular traffic
should be a minimum of four inches thick and reinforced with 6 x 6-6/6 welded wire mesh.
The mesh should be placed in the middle of the slab. Proper mesh positioning is critical to
future performance of the slabs. The contractor should take extra measures to provide proper
mesh placement. Prior to construction of slabs, the upper 12 inches of subgrade soils should
be moisture conditioned at or slightly above optimum moisture content and compacted to at
least 90 percent of the laboratory maximum dry density per ASTM 1557.
4.21 The recommendations of this report are intended to reduce the potential for cracking of slabs
due to expansive soil (if present), differential settlement of existing soil or soil with varying
thicknesses. However, even with the incorporation of the recommendations presented
herein, foundations, stucco walls, and slabs-on-grade placed on such conditions may still
Project No. 07135-42-07 -14- May 5, 2017
exhibit some cracking due to soil movement and/or shrinkage. The occurrence of concrete
shrinkage cracks is independent of the supporting soil characteristics. The occurrence may
be reduced and/or controlled by: (1) limiting the slump of the concrete, (2) proper concrete
placement and curing, and by (3) the placement of crack control joints at periodic intervals,
in particular, where re-entrant slab corners occur.
4.22 Geocon Incorporated should be consulted to provide additional design parameters as
required by the structural engineer.
5.0 Retaining Wall Recommendations
5.1 Retaining walls that are allowed to rotate more than 0.001H (where H equals the height of
the retaining portion of the wall) at the top of the wall and having a level backfill surface
should be designed for an active soil pressure equivalent to the pressure exerted by a fluid
density of 35 pounds per cubic foot (pcf). Where the backfill will be inclined at 2:1
(horizontal:vertical), an active soil pressure of 50 pcf is recommended. Expansive soils
should not be used as backfill material behind retaining walls. All soil placed for retaining
wall backfill should have an Expansion Index less than 50
5.2 Soil contemplated for use as retaining wall backfill, including import materials, should be
identified in the field prior to backfill. At that time Geocon Incorporated should obtain
samples for laboratory testing to evaluate its suitability. Modified lateral earth pressures
may be necessary if the backfill soil does not meet the required expansion index or shear
strength. City or regional standard wall designs, if used, are based on a specific active lateral
earth pressure and/or soil friction angle. In this regard, on-site soil to be used as backfill may
or may not meet the values for standard wall designs. Geocon Incorporated should be
consulted to assess the suitability of the on-site soil for use as wall backfill if standard wall
designs will be used.
5.3 Unrestrained walls will move laterally when backfilled and loading is applied. The amount
of lateral deflection is dependent on the wall height, the type of soil used for backfill, and
loads acting on the wall. The wall designer should provide appropriate lateral deflection
quantities for planned retaining walls structures, if applicable. These lateral values should be
considered when planning types of improvements above retaining wall structures.
5.4 Where walls are restrained from movement at the top, an additional uniform pressure of 8H
psf should be added to the active soil pressure where the wall possesses a height of 8 feet or
less and 12H where the wall is greater than 8 feet. For retaining walls subject to vehicular
Project No. 07135-42-07 _15 - May 5, 2017
loads within a horizontal distance equal to two-thirds the wall height, a surcharge equivalent
to 2 feet of fill soil should be added (unit weight 130 pcf).
5.5 Retaining walls should be provided with a drainage system adequate to prevent the buildup
of hydrostatic forces and should be waterproofed as required by the project architect. The
use of drainage openings through the base of the wall (weep holes) is not recommended
where the seepage could be a nuisance or otherwise adversely affect the property adjacent to
the base of the wall. The above recommendations assume a properly compacted granular (El
of less than 50) free-draining backfill material with no hydrostatic forces or imposed
surcharge load. Figure 5 presents a typical retaining wall drainage detail. If conditions
different than those described are expected, or if specific drainage details are desired,
Geocon Incorporated should be contacted for additional recommendations.
5.6 The structural engineer should determine the seismic design category for the project in
accordance with Section 1613 of the CBC. If the project possesses a seismic design category
of D, E, or F, retaining walls that support more than 6 feet of backfill should be designed
with seismic lateral pressure in accordance with Section 18.3.5.12 of the 2013 CBC. The
seismic load is dependent on the retained height where H is the height of the wall, in feet,
and the calculated loads result in pounds per square foot (psf) exerted at the base of the wall
and zero at the top of the wall. A seismic load of 2111 should be used for design. We used
the peak ground acceleration adjusted for Site Class effects, PGAM, of 0.445g calculated
from ASCE 7-10 Section 11.8.3 and applied a pseudo-static coefficient of 0.33.
5.7 In general, wall foundations having a minimum depth and width of one foot may be
designed for an allowable soil bearing pressure of 2,000 psf, provided the soil within 3 feet
below the base of the wall consists of compacted fill with an Expansion Index of less
than 90. The allowable soil bearing pressure can be increased by 300 psf and 500 psf for
each additional foot of foundation width and depth, respectively, up to a maximum
allowable soil bearing of 4,000 psf. The proximity of the foundation to the top of a slope
steeper than 3:1 could impact the allowable soil bearing pressure. Therefore, Geocon
Incorporated should be consulted where such ,a condition is anticipated.
5.8 Resistance to lateral loads will be provided by friction along the base of the wall foundation
or by passive earth pressure against the side of the footing: Allowable coefficients of friction
of 0.35 are recommended for footings in compacted fill. Passive earth pressure may be taken
as 150 pcf for walls founded on a 2:1 slope, and 300 pcf for horizontal ground in front of the
wall. The allowable passive pressure assumes a horizontal surface extending at least 5 feet,
or three times the surface generating the passive pressure, whichever is greater. The upper
Project No. 07135-42-07 -16 - May 5, 2017
12 inches of material in areas not protected by floor slabs or pavement should not be
included in design for passive resistance.
5.9 The recommendations presented above are generally applicable to the design of rigid
concrete or masonry retaining walls having a maximum height of 8 feet. In the event that
walls higher than 8 feet are planned, Geocon Incorporated should be consulted for additional
recommendations.
60 Detention Basin and Bioswale Recommendations
6.1 Any detention basins, bioswales, and bio-remediation areas should be designed by the
project civil engineer and reviewed by Geocon Incorporated. Typically, bioswales consist of
a surface layer of vegetation underlain by clean sand. A subdrain should be provided
beneath the sand layer. Prior to discharging into the storm drain pipe, a seepage cutoff wall
should be constructed at the interface between the subdrain and storm drain pipe. The concrete
cut-off wall should extend at least 6-inches beyond the perimeter of the gravel-packed
subdrain system.
6.2 Distress may be caused to planned improvements and properties located hydrologically
downstream or adjacent to these devices. The distress depends on the amount of water to be
detained, its residence time, soil permeability, and other factors. We have not performed a
hydrogeology study at the site. Downstream and adjacent properties may be subjected to
seeps, springs, slope instability, raised groundwater movement of foundations and slabs, or
other impacts as a result of water infiltration. Due to site soil and geologic conditions,
permanent bioswales and bio-remediation areas should be lined with an impermeable
barrier, such as a thick visqueen, to prevent water infiltration in to the underlying compacted
fill.
6.3 The landscape architect should be consulted to provide the appropriate plant
recommendations. If drought resistant plants are not used, irrigation may be required.
7.0 Site Drainage and Moisture Protection
7.1 Adequate site drainage is critical to reduce the potential for differential soil movement,
erosion and subsurface seepage. Under no circumstances should water be allowed to pond
adjacent to footings. The site should be graded and maintained such that surface drainage is
directed away from structures in accordance with 2013 CBC 1804.3 or other applicable
standards. In addition, surface drainage should be directed away from the top of slopes into
swales or other controlled drainage devices. Roof and pavement drainage should be directed
into conduits that carry runoff away from the proposed structure.
Project No. 0713542-07 - 17 - May 5, 2017
7.2 In the case of basement walls or building walls retaining landscaping areas, a water-proofing
system should be used on the wall and joints, and a Miradrain drainage panel (or similar)
should be placed over the waterproofing. The project architect or civil engineer should
provide detailed specifications on the plans for all waterproofing and drainage.
7.3 Underground utilities should be leak free. Utility and irrigation lines should be checked
periodically for leaks, and detected leaks should be repaired promptly. Detrimental soil
movement could occur if water is allowed to infiltrate the soil for prolonged periods of time.
7.4 Adequate drainage provisions are imperative. Under no circumstances should water be
allowed to pond adjacent to footings. The building pads should be properly finish graded
after the buildings and other improvements are in place so that drainage water is directed
away from foundations, pavements, concrete slabs, and slope tops to controlled drainage
devices.
LIMITATIONS
The conclusions and recommendations contained herein apply only to our work with respect to
grading, and represent conditions at the date of final observation on April 18, 2017. Any subsequent
grading should be done in conjunction with our observation and testing services. As used herein, the
term "observation" implies only that we observed the progress of the work with which we agreed to be
involved. Our services did not include the evaluation or identification of the potential presence of
hazardous or corrosive materials. Our conclusions and opinions as to whether the work essentially
complies with the job specifications are based on our observations, experience and test results.
Subsurface conditions, and the accuracy of tests used to. measure such conditions, can vary greatly at
any time. We make no warranty, expressed or implied, except that our services were performed in
accordance with engineering principles generally accepted at this time and location.
We will accept no responsibility for any subsequent changes made to the site by others, by the
uncontrolled action of water, or by the failure of others to properly repair damages caused by the
uncontrolled action of water. It is the responsibility of owner to ensure that the information and
recommendations contained herein are brought to the attention of the architect and engineer for the
project, are incorporated into the plans, and that the necessary steps are taken to see that the contractor
and subcontractors carry out such recommendations in the field. Recommendations that pertain to the
future maintenance and care for the property should be brought to the attention of future owners of the
property or portions thereof. The findings and recommendations of this report may be invalidated
wholly or partially by changes outside our control. Therefore, this report is subject to review and
should not be relied upon after a period of three years.
Project No. 07135-42-07 -18- May 5, 2017
Should you have any questions regarding this report, or if we may be of further service, please contact
the undersigned at your. convenience.
Very truly yours,
GEOCON INCORPORATED
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Project No. 07135-42-07 -19- May 5, 2017
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