HomeMy WebLinkAboutTract Map 30668-1 As Graded Rough Grade~~
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~ECEIVED
MAR 0 2 2004
CITY OF TEMECULA
AS-GRADED REPORT OF ROUGH GRADING
FOR HARVESTON TRACT 30668-1
LOTS 1 THROUGH 31 (HOME SITES)
CITY OF TEMECULA, CALIFORNIA
Prepared For:
Lennar Communities
391 N. Main Street, Suite 301
Corona, California 92880
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MaR o ~ 2004
February 17, 2004
Project No. 110231-024
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SAUSAidTO
Leighton and Associates, Inc. ~
A LEIGHTON GROUP COMPANY ~0~~~
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A LEIGHTON GROUP COMPANY . .
, February 17, 2004
' Project No. 110231-024
t To: Lennaz Communities
391 N. Main Sh~eet, Suite 301
Corona, Califomia 92880
' Attention: Mr. Bill Storm
' Subject: As-Graded Report of Rough Grading for Harveston, Txact 30668-1, I,ots 1 through 31
(Home Sites) City of Temecula, California.
, In accordance with your request and authorization, Leighton and Associates, Inc. (i,eighton) has been
providing geotechnical observation and testing services during rough grading operations of Tract
30668-1, located in the City of Temecula, Califomia (See Figure 1). The accompanying as-graded
' report summarizes our observations, field and laboratory test results and the geotechnical conditions
encountered during the mugh grading of Lots 1 through 31 (also referred to herein as Home Sites) of
Tract 30668-1 within the Harveston Community.
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If you have any quesfions regazding this report, please do not hesitate to contact this office, we
appreciate this opportunity to be of service.
Respectfully submitted,--
LEIGHTON AND ASS CIATES, INC.
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Rob F. Riha, CEG 921 (Exp, 02/29/(
Vice President/Principal Geologist
RFR/ATG/mm
110231-024ffinaVas-gcd ryt hact 30668-1
Q Q~ No. 1921 ~.
CERTIF!ED
~ ENCa1NEERING
~E~OOIST
. ~ telli, GE 2320
Engineer /
Copies To: (4) Addressee, (2 Unbound)
(1) Harveston Jobsite; Attention: Mr. Andy Hendrickson
(4) Greystone Homes; Attention: Ms. Mary Anne Pazadise
No. GE2320!
Exp. 12-31-05 ,
2
' 41715 Enterprise Circle N., Suite 103 ^ Temecula, CA 92590-5661
909.296.0530 ^ Fax 909.296.0534 ^ www.Ieightongeo.com
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' February 16, 2004
TABLE OF CONTENTS
' Section paae
' 1.0 IMRODUCTION ...............................................................................................................1
2.0 SUMMARY OF ROUGH-GRADING OPERATIONS ..................................................................2
' 2.1 Site Preparation and Removals .......................................................:.............................Z
2.2 Feld Density Testin9 ....................................................................................................2
2.3 Laboratory.Testin9 ......................................................................................................Z
~ 2.4 Fill Placement ..............................................................................................................3
2.5 Keyway Subdrains .......................................................................................................3
3.0 . ENGINEERING GEOLOGIC SUMMARY 4
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, 3.1 As-Graded Geologic Conditions 4
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3.2 Geologic Units ........ ...
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' 3.2.1 ArGficial FII ~A~ ..... 4
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3.2.2 Artificial Fll Leighton (Afl) ...
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3.2.3 Pauba frormation ~QP) ......................
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3.3 Geologic Structure and Faultin9 .........
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3.4 Landslides and Suficial Failures ...
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3.5 Groundwater ... ...
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3.6 Expansion Testing of. Fnish Grade Soils
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',. 4.0 CONCLUSIONS ............................................................................
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4.1 Generel 6
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2 Summary of Conciusions ...
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S.O.RECOMMENDATIONS $
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5.1 Earthwork $
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' S.1.1 Excavations $
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5.1.2 Utility Bacldll
Fil Placement and Com
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, 5.2 Foundation and Structure Design Considerations ,,,,,,,,,,,,,,,,,,,,,,,,,,,, g
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5.3 Foundation Setback from SIoP~ ........................... ................................................. 10
5.4 Structure Seismic Design Parameters ............................................................ 10
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S.SCorrosion .................
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5.6 Lateral Earth Pressures and Retaining Wall Design Considerations ,,,,,,,,,,,,,,,,
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5.7 Concrete Flatwork
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S.8 Control of Surface Water and Drainage Control
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5.9 Graded Slopes 13
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5.10 Irrigation, Landscaping and Lot (Home Site) Maintenance,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 13
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Table of Contents (cont)
' S.11 Post-Grading Geotechnical Review ............................................................................14
5.11.1 Construction Review ...........................................................................................14
' S.11.2 Plans and Specifications ......................................................................................14
I, 6.0 LIMITATIONS .....................................................................................:............................15
~ Accom~anying Faures, Tables, Plates and Appendices
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Fgure 1- Site Location Map
' Fgure 2-. Retaining Wall Drainage Detail
Tables
' Table 1- Lot (Home Site) Summary of. As-graded Geotechnical
Conditions and Recommendations
' Table 2- Minimum Post-Tensioned Foundation Design Recornmendations
Table 3- Lateral Earth Pressures
Plates
' Plate 1- As-Graded Geotechnical Map
~ Apoendices
Appendix A -. References
~ Appendix B- Summary of Feld Density Tests
Appendi~c C- Laboratory Testing Procedures and Test Results
Appendix D- Lot (Home Site) Maintenance Guidelines for Owners
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In Pocket
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' 1.0. INTRODUC7TON
In accordance with your request and authorization, Leighton and Associates, Inc. (Leighton) has
~ performed geotechnical observation and testing services during October Uurough December, 2003
for the most recent phase of rough-grading operations to create residential pads on I,ots 1 through
31 {also referred to herein as Home Sites) of Tract 30668-1 within the Harveston Community. The
t subject tract had been previously "sheeP' mass gaded under the observation and testing of Leighton
(L,eighton, 2003).
1 This as-graded report sununarizes our geotechnical observations, field and laboratory test results
and the geotechnical conditions encountered during the recent rough grading of the subject Lots
' (Home Sites) within Tract 30668-1. In addirion, this report provides conclusions and
recommendations for the continued development of the subject Lots (Home Sites).
, The reference 40-scale grading plans for Tract 30668-1 (RBF, 2003) were annotated and utilized as
a base map (Plate 1) to plot geotechnical conditions and the approximate locations of the field
density tests taken during rough-grading operations.
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' 2.0 SUMMARY OF ROUGH-GRADING OPERATIONS
' Tract 30668-1 was initially sheet graded as a portion of Lot 18 within Tract 29639-1 under the
observation and testing of Leighton (I.eighton, 2003). Rough grading to the approved Tract 30668-1
' design configuration (RBF, 2003) was conducted by ACI, Inc. in October through December of 2003,
under the geotechnical observation and testing services of Leighton. Leighton field technician(s) and
geologist were onsite on a full-time and as-needed basis, as required during grading operations.
' Previously placed fill that was left in sheet graded state was subject to erosion and surficial drying.
This phase of gading involved the removal of desiccated fill, erosion rills and surface erosion
sediments to appmved previously-placed compacted fill (Leighton, 2003) or Pauba Formation and the
, placement of new compacted fill to depths of approximately four feet above previously existing
gades to create the current design residentiat Lots (Home Sites) and associated roadways. The total
fill thiclrness is reported on Table 1(rear of text).
' 2.1 Site Preparation and Removals
' Prior to grading, deleterious materials were removed from the azeas of proposed development
and disposed of offsite. Grading of the subject site was iniriated by removal of unsuitable
surficial material. The removals were completed when pieviously approved compacted fill
~ (Leighton, 2003) or relatively non-porous Pauba Formation was encountered in accordance
with the recommendations of the project geotechnical reports (Appendix A) and the
geotechnical recommendations made during grading operations.
~ 2.2 Field Densitv Testina
, Field density testing was performed using the nuclear gauge method (ASTM Test Methods
D2922 and D3017). Tested areas appeaz to meet the' minuuum required 90 percent relative
, compaction with optimum moisture content or above. Areas that tested less than the required 90
percent relative compaction, were reworked, moishue conditioned as necessary and compacted
until the minimum 90 percent was obtained. The results and approximate locations of the field
' density tests aze ~~m,,,a,;~ed in Appendix B. The approximate locations of the field density tests
aze depicted on the enclosed As-Graded Geotechnical Map (Plate 1, in pocket).
, 2.3 Laboratorv Testina
Laboratory compaction characteristics (maximum dry density and optimum moisture),
' expansion index, Atterberg limits, and soluble sulfate tests of representarive onsite soils were
perf'ormed during the course of mugh-grading and aze presented in,Appendix C. A. description
of the laboratory test procedures aze also presented in Appendix C. The interpretakion of the
' laboratory data for each Lot (Home Site) is presented in Table 1 at the reaz of text.
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' 2.4 Fill Placement
Fill materials consisting of the soil types listed in Appendix C was placed in lifts of
, approximately eight to ten inches, processed and moisture conditioned to optnnum moisture
content or above, and compacted in place to a minunum of 90 percent of the laboratory
, derived maximum dry density. Fill placement and compaction was accomplished with the
use of heavy earthwork equipment.
, 2:5 Kevway Subdrains
y The keyway subdrain was constructed during rough grading of Tract 30668-2 (I,ots 40-42).and
Tract 30668-1 (Lots 20-21). The subdrain was constructed to outlet to the planned permanent
I~ ' ` storm drain on Harveston Drive, approximate station 75+00. The approximate location of the
subdrain is presented on the As-Graded Geotechnical Map (Plate 1). Subdrains, as constructed,
, were surveyed by RBF.
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' 3.0 ENGINEERING GEOLOGIC SUMMARY
3.1 As-Graded Geologic Conditions -
, The as-graded conditions encountered during grading of the subject lots was essentially as
' anticipated. A summary of the geologic conditions, including geologic units, geologic structure
and faulting is presented below.
, 3.2 Geologic Units
The geologic units observed during grading of the subject Home Sites consisted of Artificial
, Fill (.A~, previously-placed compacted fill (Afl), and.the Pauba Formation (Qp), which are
discussed below:
' 3.2.1 Artificial Fill (Afl - L.ocally derived artificial fill soils generally consisted of olive gray to
olive brown silty sand to locally slighfly clayey silty sand. Artificial fill soils were placed
under observation and field density testing by Leighton representatives during tlus phase of
' grading. After moisture conditioning and thomugh mixing, the artificial fill soils were
placed in lifts of appmxunately 8 to 10 inches and compacted utilizing heauy duty earth
construction equipment.
, 3.2.2 Atfificial Fill Leighton (Afl) - The azdficial fill encountered &om the previous phase of
, gading 2002/2003 generally consisted of brown to dark bmwn, moist, medium dense to
dense siity sand As encountered during grading, the artificial fill was generally modetately
dense neaz =the surface, becoming more dense with depth. The weathered artificial fill
, materials were scarified to a depth of 6 inches, moisture conditioned, thoroughly mixed
and re-used as compacted fill.
' 3.2.3 Pauba Formation (Ool - The late Pleistocene-aged Pauba Formation generally consists
of light brown to olive-brovin to medium brown, damp to moist, medium dense to dense,
siltstone, sandstone and silty claystone. Fractures are ~locally lined with calciutn
' cazbonate. The Pauba formation was moisture conditioned and re-used as compacted fill.
3.3 Geologic Structure and Faulting
1 Based on our geologic observations during site grading, the Pauba Formation is massive with
~• localized bedding, wluch is generally flat lying. No faulting or indications of faulting were
' anticipated or observed within or immediately adjacent to the subject tract. The neazest
"zoned" acrive fault is the Temecula Segment of the Elsinore Fault Zone located approximately
0.8 miles (1.281an) to the southwest.
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' 3.4 Landslides and Surticial Failures
' Based on our review of the pmject geotechnical reports (Appendix A) and our geologic
observations during the course of grading operations, there were no indications of landslides or
other siguficant surficial failures within the subject tract during this phase or previous grading
, (Leighton, 2003). It should be noted that unplanted or unprotected slopes are subject to erosion
and subsequent surficial instability.
' 3.5 Groundwater
Groundwater was not encountered during recent or previous rough grading (Leighton, 2003).
~, Canyon subdrains were constructed in general accordanoe with the project geotechnical
reports (Appendix A) and our field recommendations during the previous (Leighton, 2003)
and most recent grading. However, unforeseen conditions may occur after the completion of
' grading, and establishment of site ~irrigation and landscaping. Perched groundwater may
accumulate at layers of differing permeability or at underlying bedrock/fill contacts. If these
, conditions should occur, methods should be taken to mitigate any resulting seepage. Presently
' the majority of the subject site drains towards the west and any surface runoff will tend to
collect at low points until such time that the proposed design drainage facilities aze.constructed.
If water is allowed to pond in these azeas for any length of time the subgade in these azeas may
' become saturated and additional grading may be required to mitigate this condition. We
recommend that the project erosion confrol program be designed and implemented as soon as
possible to limit the potential of erosion damage or adverse effects to compacted fill.
, 3.6 Exaansion Testina of Finish Grade Soils _
~ Expansion index testing was performed on representative neaz fuush grade soils of the subject
Lots (Home Sites). The test results indicate the expansion potential of near-finish gade soils vary
' greafly between very low and very high in accordance with Table 18-I-B of the 1997 UBC. Test
results of samples taken during the coiuse of grading also indicates that very low to very lrigh
expansive soils exist on site at various depths and locations on the Harveston project site. Test
' procedures and results aze presented in Appendix C. An individual Lot (Home Site) inteipretation
and recommended expansion potential for design of the subject Lots is presented in Table 1.
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4.0
4.1 Genera
The grading of the subject Lots (Home Sites) was performed in general accordance with the
project geotechnical reports and geotechnical recommendations made during the course of mugh
grading. It is our professional opinion that the subject Lots (Home Sites) aze suitable for their
intended residential use pmvided the recommendations included herein and in the project
geotechnical reports aze incorporated into the design and construction of the residential structures
and associated 'unpmvements.
4.2 Summarv of Conclusions
. Geotechnical conditions encountered during rough grading of the subject site were generally
as anticipated. ,.
. Excavations were made to dense previously-placed compacted fili (Afl) material or Pauba
Formation during the gading for the subject Lots (Home Sites).
. Cut and fill slopes within the subject tract range up to approxunately 21 feet in height. It is
our opinion that the slopes on the subject tract are surficially and grossly stable (under
normal irrigation/precipitation patterns) provided the recommendations in the project
geotechnical reports and memorandums aze incorporated into the post-grading, construction
and post-construction phases of site development. Slopes aze inherently subject to erosion.
As such, measures should be taken as soon as possible to reduce erosion for both short term
and long term slope-integrity.
. Laboratory testing of soils encountered during the course of previous and current mass
grading indicates site soils may possess a very low to very high expansion potenrial and a
negligible concentration of soluable sulfate. Some expansive soil related distress to flatwork --
shoulcl be anticipated. Laboratory test results aze contained herein Table 1 and Appendix C.
. Testing for m;n;T„um resistivity, chloride concentrates, and pH. was not conducted during
the course of rough grading. A licensed conosion engineer should be contacted in regazd to
determining the potential for corrosion if corrosion sensitive buried 'unprovements aze to be
installed.
. The, potential for ground-surface rupture on the site due to a seismic event is considered to
be low; however, as in most of southem California, strong ground shaking shouid be
anricipated during the life of the structures. The standard design of structures to meet the
seismic design requirements of the Uniform Building Code (iJBC), Seismic Zone 4 will be
required.
. Where tested, fiii material placed during grading of the subject tract was placed at a
, minimum of 90 percent relative compaction (95 percent where recommended) at or above
the optimum moisture content. Field testing of compacfion was performed by the nucleaz
gauge method (ASTM Test Methods D2922, and D3017).
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. Foundations should be designed and constructed in accordance with I,eighton's minimum
recommendations herein, the requirements of the City of Temecula and the applicable
sections of the 1997 UBC.
. Due to the relatively dense nature of the bedrock materials that underlie the subject site, the
competency of compacted fills, as well as the lack of peimanent shallow groundwater, the
, potenfial for liquefaction on the site is considered to be very low.
. The front yard and driveway azeas were intenrionally left below design elevations
,; (appmximately 2 to 3.5 feet below pad grade) to accommodate future Lot (Home Site)
excavation spoils. Filling of these azeas should be performed in accordance with the
recommendations herein for earthwork (Secdon 5.1.2).
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' S.0 RECOMMENDATlONS
5.1 Earthwork
' We anticipate that fuhue earthwork at the site will consist of precise grading of the building
' pads, foundation installation, trench excavation and backfill, retaining wall backfill,
preparation of street subgade, and placement of aggregate base and asphalt concrete
pavement. We recommend that any additional earthwork on the site be performed in
, accordance with the following recommendarions and the City of Temecula grading
requirements.
, 5.1.1 Excavations - Temporary excava6ons with verticai sides, such as utility irenches,
should remain stable to depths of 4 feet or less for the period required to construct the
utility. However, in accordance with OSHA requirements, excavations geater than 5
' feet in depth should be shored, or laid-back to inclinations of 1:1 (horizontal to
vertical), if workers aze to enter such excavations. Temporary excavation greater than
4 feet should follow OSHA requirements. Leighton does not consult in the azea of
' safety engineering. The conh~actor is responsible for the safety of all excavations.
5.1.2 ti~y Backfil~, Fiil Placement and Gom ae ction -- All backfill or fill soils
~ should be bmught to optimutn moisture conditions and compacted in uniform lifts to
at least 90 percent relative compacrion based on the laboratory maximum dry density
(ASTM Test Method D1557). The optimum lift ttuckness required to produce
~ uniform compaction will depend on the type, size and condition of compacdon
equipment used. In general, the onsite soils should be placed in lifts not exceeding 8
inches in compacted thiclrness and placed on dense existing compacted fill or other
' earth material approved by the geotechxrical consultant. The backfill that coincides
with pauement subgrade should be reworked and compacted in accordance wittt
pavement design requirements.
, 5.2 Foundation and Structure Desian Considerations
, It is Leighton's understanding that single-family structures founded on post-tensioned or
conventional foundation systems aze proposed The proposed foundarions and slabs should
' be designed in accordance with the structural consultants' design, the m;r,;T„um geotechnical
recommendations presented herein (text, Tabie 1 and 2), the City of Temecula requirements
and the 1997 UBC. In urilizing the minimum geotechnical foundation recommendations, the
' structural consultant should design the foundation system to acoeptable deflection criteria as
detennined by the structural engineer and architect. Due to the lughly variable soil Types with
expansion potentials ranging from very low to very high, it is recommended that the
' eacpansion potential for the subject Lots (Home Sites) utilized in the foundalion/slab design be
as shown in Table 1.
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Foundation footings may be designed with the following parameters:
Allowable Bearine Canacitv: 2000 psf at a min;mum depth of embedment of 12
inches, plus an additional 250 psf per 6 inches of
additional embedment to a maximum of 2500 psf.
(per 1997 UBC, capaci6es may be increased by 1/3 fo;
short-term loading condirions, i.e., wind, seismic)
Sliding Coefficient: 035
Total: 1 inch
Static Settlement Potential: Differential: 1 inch in 40 feet
T'he footing width, depth, reinforcement, slab reinforcement, and the slab-on-gade. tluclrness
should be designed by the structural consultant based on recommendations. and soil
characteristics indicated herein (Tables 1 and 2), and the most recently adopted edition of the
UBC. The effects of seismic shatang on foundarion soils may increase the static differential
settlement noted above to approximately 1.25 inch in 40 feet.
The under-slab moisture retazder shouid consist of 2 inches of sand (S.E. > 30) over 10 mil
visqueen over an additional2 inches of sand (a total of 4 inches of sand). The recommended
visqueen should be sealed at all penetrarions and laps. Moisture vapor transmission may be
additionally reduced by use of concrete additives. Moisture vapor retarders may reduce but
not eliminate moisture vapor movement from the underlying soils up_ through the slabs. A
slipsheet.or equivalent should be utilized abov~ the concrete slab if crack-sensitive floor
coverings (such as ceramic tiles, etc.) aze to be placed directly on the concrete slab.
--- Our experience indicates that use of reinforcetnent in slabs' and foundations wi1L generally
reduce the potential for drying and stuinkage cracking. However, some cracldng should be
expected as the concrete cures. Minor cracldng is considered nbrmal; however, it is often
aggra~ated by a high water/cement rario, high concrete temperatures at the time of placement,
small nominai aggregate size and rapid moisture loss due to hot, dry and/or windy weather
condirions during placement and curing. Cracking due to temperature and moisture
fluctuations can also be expected. The use of low slump concrete (not exceeding 4 to 5 inches
at the time of placement) can reduce the potential for shrinkage cracldng.
Future homeowners and homeowners' association should be made aware of the importance of
' maintaining- a constant level of soil moisture. Homeowners should be made awaie of the
potential negative consequences of both excessive watering, as well as allowing soils to
become too dry. Improperly designed, constructed, or ~aintained planters often pond water
' and cause deep moisture pene~ation and soil moisture change. Since deep and repeated soil
moisture change can damage the adjacent shvcture, placement of planters adjacent to
foundations or other sensirive hardscape, such as pools and spas, should be discouraged if
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adequate and proper maintenance can not be assured. Our recommendations assume a
reasonable degree of homeowner responsibility, if the homeowners do not adequately
maintain correct irrigation and drainage, some degree of foundation movement should be
expected. However, this movement typically does not cause shuctural damage, but will cause
such things as stucco cracking and dry wall sepazation.
The slab subgade soils should be presoaked in accordance with the recommendarions
presented in Table 1 prior to placement of the moisture retazder and foundation concrete.
5.3 Foundation Setback from Slopes
We recommend a minimum horizontal setback distance firom the face of slopes for all
structural footings (retaining and decorative walls, building footings, pools, etc.). This
distance is measured from the outside bottom edge of the footing horizontally to the slope .
face (or to the face of a retaining wall) and should be a minimum of H/2, where H is the slope
height (in feet). The setback should not be less than 5 feet and need not be greater than 10
feet. Please note that the soils within the siructural setback area possess poor lateral stability
and improvements (such as retaining walls, sidewalks, fences, pools, patios, etc.) constructed
within this setback azea may be subject to lateral movement and/or differential settlement.
The potential for distress to such improvements may be mitigated by providing a deepened
footing or a pier and grade-beam foundation system to support the improvement. The
deepened footing should meet the setback as described above. Modifications of sloge
inclinations neaz foundations may reduce the setback and should be reviewed by the design
team prior to complefion of design or implementation.
5.4 Structure Seismic Desian Paremeters
Structures should be designed as required by provisions of the Uniforni Building Code (LTBC)
for Seismic Zone 4 and state-of-the-art seismic design pazameters of the Siructural Engineers
Association of California. Tlris site is located with UBC Seismic Zone 4. Seismic design
parameters in accordance with the 1997 UBC aze presented below. Please refer to the
Supplemental Geotechnical Investigation (L.eighton, 2001) for addirional information.
Seismic Source Type
Near Source Factor, Ne
Near Source Factor, N~
=B
=1.3
=1.6
Soil Profile Type _ = SD
Horizontal Peak Ground Accelerarion = 0.68g
(10% probability of exceedance in 50 yeazs)
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, 5.5 Corrosion
For sulfate exposure and cement type refer to Table 1 and the corresponding sections of the
, UBC. Corrosion tests such as, pH, resisrivity and chloride concentra6on were riot
performed as part of this observation during rough grading. Other than buried concrete
improvements, a licensed corrosion engineer should be contacted in order to determine the
, potenrial for coaosion if corrosion sensitive buried improvements aze planned.
~ 5.6 Lateral Earth Pressures and Retaining Wall Design Considerations
The recommended lateral pressures for very low to low expansive soil (expansion index less
' than 51) and level or sloping backfill aze presented on Table 3(reaz of text). The onsite wall
excavation materials should be reviewed by the geoteclurical consultant prior to use as wall
backfill:
' Embedded structural walls should be designed for lateral earth pressures exerted on them. The
magnitude of these pressures depends on the amount of deformation that the wall can yield
' under load. If the wall can yiefd enough to mobilize the full sheaz strength of the soil, it can be
designed for "active" pressure. If the wall cannot yield under the applied load, the shear
, strength of the soil cannot be mobilized and the earth pressure will be lugher: Such walls
' should be designed for "at rest" conditions. If a structure moves towazd the soils, the resulting
resistance developed by the soil is the "passive" resistance.
, The equivalent fluid weights of Table 3 assume very_ low to low expansive, free-draining
conditions. If conditions other than those assuxned above aze anticipated, equivalent fluid
weights should be pmvided on a case by case basis by the geotechnical engineer. Surchazge
' loading effects from adjacent siructures should be evaluated by the shuctural engineer. All
retaining wall shuctures should be pmvided with appropriate drainage and waterproofing. The
' outlet pipe should be sloped to drain to a suitable outlet. Typical wall drainage design is
illustrated in Figure 2.
`' Lateral passive pressures may be determined using the values provided in Table 3. In
combining the total lateral resistance, the passive pressure or the frictional resistance should
be reduced by 50 percent. Wa11 footings should be designed in accordance with structural
~ considerations. The passive resistance value may be increased by one-third when considering
loads of short duration, including wind or seismic loads: The horizontal distance between
, foundation elements providing passive resistance should be a minimum of three times the
' depth of the elements to allow full development of these passive pressures. The total depth of
retained earth for design of cantilever walls should be the vertical distance below the ground
, surface measured at the wall face for stem design or measured at the fieel of the footing for
' overturning and sliding.
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' - li- Leighton
,
110231-024
, February 17, 2004
' Foundarions for retaining walls in competent formational soils or properly compacted fill
should be embedded at least 18 inches below the lowest adjacent finish grade. At this depth,
an allowable bearing capacity of 2,250 psf may be utilized. The bearing capacity may be
, increased by 250 psf for each additional six inches of embedment to a maximum of.4000 psf.
, Wall backcut excavations less than 4 feet in height can be made near vertical. For backcuts
greater than 4 feet in height, the backcut should be flattened to a gradient not steeper than 1:1
(horizontal to vertical). Backfill soils should be compacted to at least 90 percent relarive
~ compaction (based on ASTM Test Method D1557). Backfill should extend horizontally to a
miniinum distance equal to one-half the wall height behind the wa11s. The walls.should be
constructed and backfilled as soon as possible after backcut excavation. Prolonged exposure
, of backcut slopes may result in some localized slope instability.
For unrestrained retaining walls within this tract that aze greater than 5 feet (exposed; retained
, earth) or that may present a life/safety hazazd during slrong ground shaking, the lateral earth
pressures should be. increased by a seismic surchazge (seismic increment) in general
accordance with chapter 16 of the 1997 UBC. The locafion, dislribution and magnitude of this
' surcharge will be pmvided if such walls are proposed. The design of walls including such
seismic increment should achieve a factor of safety between 1.1 and 1.2 when. evaluating
stability (sliding and overtuming) of the wall (NAVFAC DM7.02).
~ 5.7 Concrete Flatwork
~ Expansive soils are lmown to exist onsite and therefore concrete flatwork should be designed
and constructed with the anticipation of expansive soil related distress. Gloser spacing. of
control joints, reinforcement and keeping the flatwork subgrade at or above optimum soil
' moisture (elevated soil moisture content) prior to the placement of concrete may min;mize
cracking and differential movement.
' City of Temecula Standard No. 401 "Sidewalk and Curb" specifies aggregate base or
approved select material under sidewalks and curbs when expansive soil is present. In lieu of
' the aggregate base or select material under sidewallcs and curbs, and with the approval of the
City of Temecula, the sidewalk and curb subgrade may be presoaked such that 120% of
, optimum moisture content to a minimum depth of 8 inches is achieved prior to the.placement
of concrete. Moisture testing must be performed by the geotechnical consultant prior to
!. concrete placement.
'
'
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' _ lZ - Leighton
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'
110231-024
' February 17, 2004
t 5.8 Control of SurFace Water and Drainage Contro
Positive drainage of surface water away from structures is very important. No water should be
, allowed to pond adjacent to buildings. Posirive drainage may be accomplished by providing
drainage away from buildings at a gradient of at least 2 percent for a distance of at least 5 feet,
and further maintained by a swale on drainage path at a gradient of at least 1 percent Where
' limited by 5-foot side yards, drainage should be directed away from foundations for a
maumum of 3 feet and into a collector swale or pipe system. Where necessary, drainage paths
' may be shortened by use of azea drains and collector pipes andlor paved swales. Eave gutters
also help reduce water infiltrarion into the subgrade soils if the downspouts aze properly
connected to appropriate outlets.
' Planters with open bottoms adjacent to buildings should be avoided, if possible. Planters
should not be designed adjacent to buildings unless provisions for drainage, such as catch
' basins and pipe drains, are made. No ponding of water from any source (including
irrigation) should be permitted onsite as moisture infiltration may increase the potential for
moisture-related distress. Experience has shown that even with these controls for surface
' drainage, a shailow perched ground water or subsurface water condition can and may
develop in azeas where no such condition previously existed. This is particularly true where
a substantial increase in surface water infiltration resulting &om site imgation occurs.
' Mitigation of these condirions should be performed under the recommendations of the
geotechnical consultant on a case-by-case basis.
~ 5.9 Greded Slooes
It is recommended that all slopes be planted with drought-tolerant, ground cover vegetation
' as soon as practical to protect against erosion by reducing runoff velocity. Deep-rooted
vegetation should also be- established to provide resistance to surficial slumping.
Oversteepening of existing slopes should be avoided during fine grading and construcrion.
' Retaining structures to support graded slopes should be designed with structural
considerations and appropriate soil parameters provided in Sectiqn 5.6.
, 5.10 Irrigation Landscaping and Lot (Home Site) Maintenance ~
' Site irrigation should be controlled at ail times. We recommend that only the minimum
amount of ixrigation necessary to maintain plant vigor be urilized. F'or irrigation of trees and
shrubs, a drip irrigation system should be considered. We recommend that where possible,
' landscaping consist prnnarily of drought-toleraut vegetation. A landscape consultant should
be contacted for proper plant selection. For lazge graded slopes adjacent to open space
ateas, we recommend native plant species be utilized and that irrigation be utilized only
' unril plants are well established. At that time, irrigation could be significantly reduced.
, ~
' -13- Leighton
~~
,
110231-024
' February 17, 2004
, Upon sale of home, maintenance of the I.ots (Home Sites) and common azeas by the
homeowners and homeowner's associarion, respectively, is recommended. Recommendarions
for the maintenance of slopes and property are included in Appendix D for your review and
, dishibution to future homeowners and/or homeowner's associarions.
' 5.11 Post-Grading Geotechnical Review ,
5.11:1 Construction Review -- Construction observarion and testing should be performed
' by the geotechnical consultant during future excavations, utility trench backfilling
and foundation or retaining wall construction at the site. Additionally, footing
excavations should be observed and moisture determination tests of subgade soils
' should be performed by the geotechnical consultant prior to the pouring of concrete:
5.11.2' Plans and Soecifications -- The geotechnical engineer should review foundarion
' plans to evaluate if the recommendations herein haue been incorporated. Foundation
design plans and specificarions should be reviewed by the geotechnical consultant
prior to excavation or installation of residential development.
1
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' -14 - Leighton
1
110Z31-024
t February 17, 2004
' 6.0 LIMITATIONS
The presence of our field representative at the site was intended to provide the owner with
' professional advice, opnuons, and recommendarions based on observa6ons of the contractor's
work. Although the observations did not reveal obvious deficiencies or deviations from project
' specifications, we do not guazantee the contractor's work, nor do our services relieve the conh~actor
or his subcontractors of their responsibility if defects aze subsequently discovered in their work. Our
responsibilities did not include any supervision or direction of the actual work procedures of the
' contractor, lus personnel, or subcontractors. The conclusions in this report aze based on test results
and observations of the grading and earthwork procedures used and represent our engineering
opinion as to the compliance of the results with the proj ect specifications.
'
,
,
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'This report was prepared for I,ennaz Communities, based on their needs, directions, and requirements
ai the time. This report is not authorized for use by, and is not to be relied upon by any party except,
Lennaz Communities, with whom L,eighton contracted for the work. Use of or reliance on trris report
by any other party is at that party's risk. Unauthorized use of ar reliance on this Report constitutes an
agreement to defend and indemnify Leighton and Associates from and against any liability which may
arise as a result of such use or reliance, regazdless of any fault, negligence, or strict liability of
I.eighton and Associates.
~ -.15-
•
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Base Map: The Thomas Guide Digital Edition Inland Empire 2004, Not To Scale
Harveston Project No. ~
Tract 30668-1, SITE LOCATION »023~-oza ~~~
Temecula, California MAP Date '~ ~
Riverside County, California Februarv2oo4 FgureNo.1
SUBDRAIN OPTIONS AND BACKFlLL WHEN NATNE MA?ERL4L HAS DCPANSION INDIX OF >50
WALL HQGHI'
OR HEEL WID7H
WHICHE/Bt
IS GREATHt
. . ~`
~ ~ WATERPROOF
PER DE4GN
lY ENGIN~i
~ . CLEAN SJWD BAIXRLL
. ~ ' . WIfHSE>3~.
~ APPROVED BY $OIISBJGIN~t
(M4Y BE DBJ4FI~ BY NMPACTICN
OR.WA7ER]ETfING)
. . ~
~ . . ~~ FR'fERFABRIC
WEEP HOIE . (SEE NQfE 4)
(SEE NQfES~ _: 4
_,
.' .
- ~
I'•
• 4" PERFORATED PIPEANDGRAVa
~ 6" NIIN. ~^ (SEE NOTES 2 AND ~.
: y.
~
- NOTE AS AN ALTH3NA7E TO QFAN S4ND BPLlfflll,
CIFAN GPAVEI MqY BE UTIUZED WCTH APPR~VED F7LTHt FABRIG A
~ SECOND ALTFRNATE IS TO UTILIZE AN AGGHEGA'tE 645E M4T@tipl
~ COMPACTED T090 % RELA7IVE COMPACiION. A SAN~IE CF'f}~
PROPOSED BASE MUST BE APPROV~ BY THE GEQIC4QJICAL .
~ . CCNSULTANTPRIORTOBPLIffIl1FOR5VITABILITY.COMPACflON
SHOULD BE AQiIEVED Wf7H0UT 0.4MAQNG THE WPll.
I GENERALNOTES:
~ Waterproofing should be proNded where moisture nuisance problem through the wali is undesiraWe.
Water pro~ng of the walls is not under purview af fhe geotechnipl engineer
I* All drains should have a 9radtent of i percent miNmum
~Outlet portion oF the subdrain should have a 4-inch diam~er solid pfpe discharged fnto d:suitable disposal aYea designed by the project
ngineer. The subdra(n ppe should be aaessible for maintenance (roddng)
Other subdrain bacl~iii options are sub~ect to the revfew lry the geotechnical engineer and motlification of design parameters.
otes:
,~) $and should have a sand equlvalent of 30 or greater and may be densified by water jetting. '
) 1 Cu. ft. per ff, of 1/4- to 1 1/2-inch size cga~i wrapped in fiites fabric
3) Pipe type should be ASTM D1527 Ac .rylonRrite Butadiene Styrene (ABS)SDR35 aA5'fM D1785 Polydnyl Chloride pastic (WG~, Schedule
~0; Armw A2000 PVC, or approved equivalent. Pipe should be installed with perforations down. Perforations should be 3/8 inch in
Iameter placed at the ends of a 120-degree arc in two rows at 3-inch on center (stagger~
4) Filter fabric should be Mfrafl 140NCwapprvved equiralent
~Weephole should be 3-inch mfnimum diameter and proNded at lafoot maximum intenals. If ocposure is permitted, weephofes should
located 12 inches above finished grade, If ocposure is not permitted such as for a wall adjacent to a sidewalk/curb, a pipe underthe
idewalk to be discharged through the curb face or equivalent should be provided. For a basement-type wall, a proper subdrain outlet
system should be provided.
'~) Retaining wall plans should be reviewed and approved lry the geotechnicai engineer. .
~ ) Walls o~er six feet in height are subjed to a special reNew by the geotechnical engineer and modflcations to the above requirements.
,y RETAINING WALL BACKFILL AND SUBDRAIN DETAIL
FOR WALLS 6 FEET OR LESS IN HEIGHT ~
WHEN, NA7IVE MATEftIAL HAS IXPANSION INDEX OF >50
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110231-024
February 17, 2004
TABLE 2
Minimum Post-Tensioned Foundation Design Recommendations
Expansion Potential (LJBC 1&2)
Design Criteria
Very Low
Low
Medium High
Very High
EI= 0-20 EI= 21-50 EI= 51-90 EI
1 EI =>130
130
Edge Center Lift: 5.5 feet 5.5 feet
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Variation e,,; ~Se Lift: 3A feet 5.0 feet
Differential Center Lift: 1.25 inches 2.0 inches. 2.4 inches 4.5 inches 5.0 inches-
Swell, ym
Edge Lift: 0.4 inches 0.4 inches 0.8 inches 13 inches 2.0 inches
Modulus of Subgrade .
Reaction 150 psi/in 125 psi/in 125 psi/in 100 psi/in 75 psi/in
Plasticity Index Non * * * *
Plasric
Minimum Perimeter Footing
Embedment Depth 12 inches 12 inches 18 inches 24 inches 30 inches
Underslab Treahnent Two inches of sand over a 10-mil polyvinyl membrane (Visqueen
--- or uivalent over an addirional two inches of sand.
Presoaking See Table 1
(1) Depth of exterior footing to be measured from lowest adjacent &nish grade or drainage swale flowiine elevation (less
~ than 5 feet laterally from footing, per code). - ~
(2) Living azea slabs should be tied to the footings as directed by the shucturai engineer.
(3) Detailing of expansion crack contro] joinu for PT slabs per structural engineer.
(4) Underslab treatment sand should have a Sand Equivalent of 30 or greater (e.g. washed concrefe sand).
(5) , 1'he lower two inches of underslab ueatment sand may be omitted on Home Sitas wlrich possess a very low
expansion potenrial (see Table 1). '
(6) Potential total and differential settlement should be included cumulatively witL differenrial swell parameters.
* Plasticity index to be provided upon request if a ribbed UBC type (Secrion 1815) slab is preferred
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TABLE 3
Lateral Earth Pressures~4
For Ve Low to Low Ex ansive Soil Backfiil
Equivalent Fluid Weight (pcfl
Conditions
Level BackfiliZ 2:1 Slope Backfill
Active 45 67
At-Rest 65 95
Passive3 300 125 (Sloping Down)
~Assumes drained condition (See Figure 1)
ZAssumes a level condition behind and in front of wall foundation of project
3Ma~cimum passive pressure = 4000 psf, level conditions.
°Assiunes use of very low to ]ow expansive soil (EI= 0-50).
110231-024
February 17, 2004
/
2`'
' 110231-024
February 17, 2004
, ~
, APPENDDC A
~ References
' Leighton and Associates, 2001, Supplemental Geotechnical Invesrigation: and Geotechnical
Review of 100-Scale Mass Grading Plan, Tentative Tract No. 29639,
. Harveston, Temecula, Califomia, LDOl-058GR, Project No. 110231-003,
' dated August 15, 2001.
Leighton and Associates, 2003, As-Graded Report of Mass Grading Hazveston, Tract 29639-1, City
' of Temecula, Califomia, Project No. 110231-006, dated February 5, 2003.
Naval Facilities Engineering Command, 1986a, Soil mechanics design manual 7.01, Change l:
' U.S. Navy, September.
Naval Faciliries Engineering Command, 1986b, Foundations and earth structures, design manual
' 7.02, Changes 1: U.S. Navy, September.
RBF Consulting, 2003, Harveston Tract 30668, -1, and -2 Rough Grading and Erosion Control
, Plan, October 2003, LD03-013GR, Sheet 4 of 5.
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Leighton
110231-024
February 17, 2004
APPENDIX B
~x~lanation of Summarv of Field Density Tests
A: Retest of previously failing compaction test.
B: Second retest of previously failing compaction test.
Compaction tests taken during mass grading of site unless indicated by:
FG: Compaction tests taken on rough finish grade.
SF: Compaction tests taken on slope face.
Test Location: Indicated by Home Site number.
Test Method: Compacrion test by Nucleaz Gage (ASTM 2922) unless indicated by
S: Sand Cone Method (ASTM 1556).
Test Elevation: Approximate elevation above mean sea level.
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'
APPENDDCC
, Laboretorv Testina Procedures and Test Results
110231-024
February 17, 2004
' Expansion Index Tests: The expansion potential of selected materials was evaluated by the
Expansion Index Test, ASTM test method D4829 or U.B.C. Standard No. 18-2. Specnnens aze
, molded under a given compactive energy to approximately the optimum moisture content and
approximately 50 percent satuntion or approximately 90 percent relative ;compaction. The
prepared 1-inch thick by 4-inch diameter specimens aze loaded to an equivalent 144 psf surchazge
~ and aze inundated with tap water until volumetric equilibrium is reached. The results of these tests
are presented in the table below and in the soil characterisrics table herewith Appendix C:
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Sample Location Saxnple Description Expansion
Index Expansion
Potential
Lots 1-4 Brown silty clayey SAND, SGSM 40 I.ow
Lots 5-7 Olive brown lean CLAY, CL 91 High
Lots 8-10 Olive brown lean CLAY, CL 111 High
L.ots i 1-13 Olive brown lean CLAY, CL 144 Very High
Lots 14-17 Brown lean CLAY, CL 102 High
Lots 18-21 Brown clayey SAND, SC 48 Low
Lots 22-24 Brown lean CLAY, CL 92 High.
I.ots 25-28 Brown lean CLAY, CL 110 H~~
I,ots 29-31 Brown lean CLAY, CL 118 High
~ G1 ~
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, 110231-024
, February 17, 2004
' APPENDDC D
1 e~(,dom Si Q,1 Maintpnance G~idelines for Owners
~ Development areas, in general, and hillside Home Sites, in particular, need maintenance to continue
' to function and retain theu value. Many owners aze unawaze of tlus and allow deterioration of the
properry. It is important to familiarize owners with some guidelines for maintenance of their
pmperties and make them awaze of the importance of maintenance.
, Some goveming agencies require lullside property developers to utilize specific methods of
engineering and construction to protect those investing in improved Home. Sites or consh~ucted
' homes. For example, the developer may be required to grade the property in such a manner that
rainwater will be drained away from the Home Site and to plant slopes so that erosion will be
miuinuzed. They may also be required to install permanent drains.
' However, once the Home Site is purchased, it is the buyer's responsibility to maintain these safety
features by observing a prudent program of Home Site caze and maintenance. Failure to make
, regular inspection and maintenance of drainage devices and sioping areas may cause severe
financial loss. In addition to their own property damage, they may be subject to civil liability for
damage occurring to neighboring properties as a result of his negligence.
~ The following mainfenance guidelines aze provided for the protecrion of the owner's investment.
, a) Caze should be taken that slopes, terraces, berms (ridges at crown of slopes) and proper Home
Site drainage are not disturbed. Surface drainage should be conducted from the reaz yard to
the sh~eet through the side yazd, or altemative approved devices.
, b) In general, rooF and yard runoff should be conducted to either the street or storm drain by ---
nonerosive devices such as sidewalks, drainage pipes, ground gutters, and driveways. Drainage
' systems should not be altered without expert consuitation.
, c) All drains should be kept cleaned and unclogged, inciuding gutters and downspouts. Terrace
drains or gunite ditches should be kept free of debris to allow proper drainage. During heavy
rain periods, performance of the drainage system should be inspected. Problems, such as
,. gullying and ponding, if observed, should be corrected as soon as possible.
d) Any leakage from pools, water lines, etc. or bypassing of drains should be repaired as soon as
' practical. -
e) . Annnal burrows should be eliminated since they may cause diversion of surface runoff,
' promote accelerated erosion, and even trigger shallow soil flowage.
'
, D-1 ~
' 110231-024
' February 17, 2004
' ~ Slopes should not be altered without expert consnltation. Whenever a significant topographic
modification of the Home Site or slope, is desired a qualified geotechnical consultant should
be contacted.
, g) If the owner plans to modify cut or natiu~al slopes aze proposed, an engineering geologist
should be consulted. Any oversteepening may result in a need for expensive retaining devices.
' Undercutting of a toe-of-slope would reduce the safety factor of the slope and should not be
undertaken without expert consultation.
, h) If unusual cracking, settling or earth slippage occurs on the property, the owner should consult
' k) Owner's should be aware of the chexnical composition of imported soils, soil amendments, and
fertilizers to be utilized for landscaping purposes. Some soils, soil amendments and fertilizer
can leach soluble sulfates, increasing soluble sulfate concentrations to moderate or severe
' concentrations, negatively affecting the performance of concrete improvements, including
foundations and flatwork.
'
,
a qualified soil engineer or an engineering geologist immediately.
' i) The most common causes of slope erosion and shallow slope failures aze as follows:
• Gross neglect of the caze and maintenance of Yhe slopes and drainage devices.
' • Inadequate and/or nnproper planting. (Barren azeas should be replanted as soon as
possible.)
' • Excessive or insufficient irrigation or diversion of runoff over the slope. ,
~ j) Hillside Home Site owners should not let condi6ons on their property create a problem for
their neighbors. Cooperation with neighbors could prevent problems, promote slope stability,
adequate drainage, proper maintenance, and also increase the aestheric attractiveness of the
, community. -
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