HomeMy WebLinkAboutGeotechRoughGrading(Jul.5,1990)
I
I
I
I
-I
I
I
-I
'I
I
I
I
I
I
I
I
I
I
I
LEIGHTON AND ASSOCIATES, INC
Geotechnical and Environmental Engineering Consultants
GEOTECHNICAL REPORT OF ROUGH GRADING
TRACT 23101-2. LOTS 1-108
. CHARDONNAY HILLS RESIDENTIAL DEVELOPMENT
CITY OF TEMECULA
RIVERSIDE COUNTY, CALIFORNIA
July 5, 1990
Project No. 11871347-05
Prepared for:
Marlborough Development Corporation
28751 Rancho California, Suite 208
Temecula, California 92390
27715 JEFFERSON AVENUE, SUITE 109, TEMECUlA, CALIFORNIA 92390
(714) 676-0023
FAX (714) 676-6826
\
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
LEIGHTON AND ASSOCIATES, INC
Geotechnical and Environmental Engineering Consultants
July 5, 1990
Project No. 11871347-05
To: Marlborough Development Corporation
28751 Rancho California Road, Suite 208
Temecula, California 92390
Attention: Mr. Pete Noyes
Subject: Geotechnical Report of Rough Grading, Tract 23101-2, Lots 1-108,
Chardonnay Hills Residential Development, City of Temecula, Riverside
County, California
Introduction
In accordance with your request, Leighton and Associates, Inc., is pleased to
present this geotechnical as-graded report for Tract 23101-2. Included herein
are observations, field and laboratory test results, conclusions and
recommendations for this development. All grading was conducted in accordance
with Riverside County specifications and our recommendations.
Accomoanvinq Maos. Tables. and Aooendices
Figure 1
T'abl e 1
'j;able 2
Table 3
hble 4
Table 5
Plates 1 through 5
Appendix A
Appendix B
- Site Location Map
- Maximum Dry Density Test Results
- Field Density Test Results
- Expansion Index Tests
- Lot Classification
- Foundation Design Considerations For Expansive Soils
- As Graded Geotechnical Maps
- References
- Slope Maintenance Guidelines for Homeowners
27715 JEFFERSON AVENUE, SUITE 109, TEMECUlA, CALIFORNIA 92390
(714) 676-0023
FAX (714) 676-6826
-z.,
.
.
...
.
I
I
I
I
.
I
I
I
I
I
I
.
~J
]111
.0
.
scale
SITE LOCATION MAP
-Base Map:
U.S.G.S. Bachelor Mtn. California
dated 1953, photorevised 1973
7.5 minute quadrangle,
CHARDONNAY HILLS
Project No. 1 1 87 1347'- 0 5 [JfJ[TI
TRACT 23101-2 Date 07/05/90
Drafted by MDK 1040 8B9
Figure No.1 ~
1
I
1
1
1
I
1
I
1
I
1
1
1
1
1
1
I
1
1
Project No. 11871347-05
Summary of Rouqh Gradinq Ooerations
Rough grading began on this and adjacent tracts in November of 1989. Grading
was performed by E. L. Yeager Construction Co., Inc., of Corona, Ca 1 iforni a.
Gradi ng generally conforms to the 1" = 40' gradi ng plans prepared by Communi ty
Engineering Services, Inc., of Riverside California. Geotechnical observation
and testing services were conducted by Leighton and Associates, Inc., Temecula
office.
A summary of grading operations follows;
. Site vegetation was not consi dered dense and was di sced in place and
disseminated throughout the deeper fill soils during grading. Our
observations during grading revealed no adverse geotechnical conditions.
. Soil was transported util izing heavy duty conventional grading equipment
consisting of Caterpillar 633, 657, and 639 type scrapers. Caterpillar 824's
were used for mixing and compacting the fill soils. The fill materials were
moisture conditioned utilizing 4000 and 8000 gallon water trucks.
. Alluvial removals were conducted in the low lying canyons and swales. Older
alluvium was left in place when the in-place density exhibited at least 85
percent of the maximum dry density and near optimum moi sture content as
determined by ASTM DI557-78. Field density tests conducted in these natural
alluvial soils are designated as Natural Ground Tests (NG) on Table 2 (Field
Density Test Results).
Prior to fill placement, topsoil was removed and the underlying soils were
ripped, moisture conditioned and recompacted. Fill soils were placed in
approximately 4- to 8-inch loose lifts, moisture conditioned then compacted.
Representatives of this firm were on site on a full time basis to observe,
test and document fill placement and grading operations.
Pri or to construct i ng fill slopes, keys were excavated at the toe of the
slopes after construction stakes were set. Keys were typically 14 to 16 feet
wide and tilted into slope with approximately two feet of bedrock exposed in
the toe of the excavation.
.
.
Fill soils were compacted then tested to evaluate the relative density of the
fill areas. Field density tests were conducted in general accordance with
ASTM D1556-82 (sand cone), ASTM D2922-81 (nuclear gauge), and ASTM D2937-83
(drive cylinder) methods. In our opinion, grading operations were conducted
in general accordance with our recommendations and the specifications of the
County of Riverside.
Overexcavated Lots
Lots exposing a transition (cut/fill) line at finish grade within the building
location were overexcavated in the cut portion to a depth of approximately 3 feet
3
~
I
I
I
I
I
I
1
1
I
I
I
1
I
I
I
I
I
1
1
Project No. 11871347-05
to provide a uniform fi 11 cap for supporting the footings of the proposed
residential structures.
:Exoansion Index
Expansion index tests were performed on representative samples from the subject
lots to evaluate the expansion potential of the near-surface soils. Expansion
index tests were performed in general accordance with the UBC Standards Test
Method 29-2. Our laboratory tests indicate the near surface soils range from
very low to high on the Expansion Index (0-20, very low; 21-50, low; 51-90,
medium; 91-130, high). The results of our expansion tests are presented in Table
3.
:Table 4 of this report provides the presaturation requirements for the
corresponding expansion index for each respective lot. Presaturation of the slab
subgrade is recommended prior to placement of concrete and the moisture barrier,
-and should be verified by a representative of this firm.
Enqineerinq Geoloqy
'The geologic units encountered during grading were mapped within the
boundary and are indicated on the As-Graded Geotechnical Maps (Plates 1
5). The predominate underlying bedrock unit is the Pauba Formation.
the geologic units is described briefly below.
,. ODS - Ouaternary Pauba Formation
project
through
Each of
The Pauba Formation consists of tan, medium to dark brown, silty, fine to very
coarse sands. Occasional traces of clay are also present. Exposed cut areas
were geologically mapped and are designated as Qps on the accompanying maps.
-. Af - Fill Soils Placed Durinq Gradinq
Fill soils, designated as Af on the accompanying maps were placed and
compacted during grading under the observation and testing of Leighton and
Associates, Inc., Temecula office.
'. Colluvium/Slooewash/Toosoil (not a maDDed unit)
Surficial units such as colluvium, topsoil, and slopewash were encountered
throughout the majority of the site. These surficial units generally
consisted of dark brown, moist, loose, silty, fine to coarse sands to clayey
sands. All unsuitable surficial units were removed during earthwork
operations.
4
s
I
I
I
1
I
I 1
I
1
I
I
I
I
I
I
I
1
I
1
I
Project No. 11871347-05
. Oalo - Alluvium
Stream deposited alluvium is generally comprised of medium to dark brown,
silty fi ne to very coarse sands . All uvi a 1 removals were performed in the
natural canyons and generally flat lying drainages at the site. Alluvial
removals conducted in these areas were excavated to a depth that revealed a
moist condition and at least 85 percent in-place density as determined by ASTM
DI557-78.
Ground Water
No ground water was encountered during grading. Subdrains were not installed
in any canyons or clean-out areas.
FaultinQ
No active or potentially active faults were encountered during rough grading
operations.
Conclusions and Recommendations
. Our field observations, testing and laboratory test results indicate that the
structural fill soils placed during grading have been compacted to at least
90 percent relative compaction as determined by ASTM DI557-78.
. Geotechnical aspects of the site have been evaluated during rough grading.
It is our opinion that the grading was performed in general accordance with
our recommendations and the specifications of the County of Riverside.
. Cut portions of transitions lots were overexcavated to a minimum depth of 3
feet, scarified, watered and recompacted prior of the placement of fill.
. All slopes are considered grossly stable provided that positive drainage is
maintained away from the slope, and they are planted with appropriate
vegetation as soon as possible to reduce future erosion and slope
deterioration. Due to the generally friable nature of the sands on the cut
slopes, immediate slope planting would be prudent.
. Key excavations were made at the toe of fill slopes. Benching of alluvial
and coll uvi a 1 soi 1 s duri ng fi 11 placement was performed to provide a fi rm
contact between natural ground and the compacted fill soils.
5
"
I
I
1
1
I
I
I
I
I
I
I
I
I
I
I
I
I
1
I
Project No. 11871347-05
Recommendations
.
Foundation Recommendations
The following recommendations are considered mlnlmum and are dependant upon
the expansive conditions of each lot, see Tables 3, 4 and 5. Also, these
recommendations may be superseded by more restrictive requirements of the
architect, structural engineer, building code, or governing agencies.
We anticipate that the proposed residential buildings will be one- to two-
story, wood frame construction, and will utilize conventional, continuous or
isolated spread footings. Footing width for a single story building should
be a minimum of 12 inches (15 inches for a two story structure), have a
minimum embedment of 12 inches (18 inches for a two story structure) below
the lowest adjacent grade. Isolated spread footings should have a minimum
width of 24 inches and be rei nforced in accordance with the structural
engi neer' s recommendations. At a depth of 12 inches the foot i ngs may be
designed for an allowable bearing pressure of 1500 psf. The bearing value
may be increased by 300 psf for each additional foot of embedment. Bearing
pressures may be increased by one-third when considering short term loadings
such as wind loads or seismic forces.
Floor Slabs
Slabs should have a mlnmum thickness of 4 inches and be reinforced at
midheiqht in accordance with Table 5. Slabs should be underlain by a 2-inch
layer of clean sand with a sand equivalent of 30 or greater (for concrete
curing purposes), which is underlain by a 6-mil (or heavier) moisture barrier,
(see Table 5). _ Garage slabs should be isolated from the perimeter footings
and provided with sawcut control joints. Appropriately spaced sawcuts should
be considered for all slabs to control nuisance cracking. Sawcuts should be
a mi nimum of t the depth of the slab. We emphas i ze that it is the
responsibility of the contractor to insure that the slab reinforcement is
placed at midheight of the slab. Our experi ence i ndi cates that use of
reinforcement in slabs and foundations will generally reduce the potential
for drying and shrinkage cracking. However, some cracking should be expected
as the concrete cures. Minor cracking is considered normal, however, it is
often aggravated by a high water/cement ratio, high concrete temperature at
the time of placement, small/nominal aggregate size, and rapid moisture loss
due to hot, dry, and/or windy weather conditions during placement and curing.
Cracking due to temperature and moisture fluctuations can also be expected.
The use of low slump concrete not exceeding 4 inches at the time of placement
is recommended. The contractor should take appropriate curing precautions
during placement of concrete to minimize cracking of slabs. We recommend that
a slipsheet (or similar) be utilized if tile or other crack-sensitive flooring
is planned directly on the concrete slab. Slabs should be designed in
accordance with structural considerations.
6
1
I
I
I
I
I
I
1
I
I
I
I
I
I
I
I
I
I
I
I
Project No. 11871347-05
Presoaking of slabs subgrade should be performed in accordance with Table 4
(Lot Classification) prior to placement of concrete.
. Additional Considerations
Building pads should be fine graded to provide drainage to the street or to
approved drainage facilities. Water should drain away from the residence at
a minimum gradient of 2 percent. Low areas which might pond water should be
regraded or provided with catch basins and closed drain pipes to direct site
waters to the street or approved drainage facilities.
It is prudent that residential structures be provided with roof gutters and
downspouts. Downspout water shoul d be di rected to the street or proper
facilities by buried drainpipe or other approved means.
Rainwater or irrigation water intercepted by the building pad area should not
be allowed to overtop slopes.
Proper slope landscaping and maintenance is important to maintain slope
integrity. For slopes not directly maintained by a homeowners association,
the homeowners should be reminded of the responsibilities of being a hillside
resident. Appendix B provides slope maintenance guidelines for homeowners.
A qual ifi ed 1 andscape architect shoul d be consulted for speci fi c
recommendations. Overwatering should be avoided as this can cause saturation
of the surface soils, and could cause slumping of slope surfaces.
All slopes should be planted with ground cover and deep-rooted native type
shrubs or trees as soon as possible. Shallow-rooted shrubs and trees provide
protection against surficial slumping.
We recommend a minimum setback from the face of slopes for all foundations
and settlement sensitive structures proposed near the tops of slopes. This
distance is measured from the outside 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.
We should note that the soils within the structural setback area possess poor
lateral stability, and improvements (such as retaining walls, pools,
sidewalks, fences, pavements, etc.) constructed within this setback area may
be subject to lateral movement and/or differential settlement.
Construction observation of foundations should be performed by an engineering
geologist and/or soil engineer after appropriate presaturation and prior to
placement of steel and pouring of concrete.
7
B
I
I
I
I
I
I
I
I
I
.
I.
.
I
I
I
I
.
I
I
Project No. 11871347-05
Thank you for this opportunity to be of service to you. If you should have any
questions regarding this report, please do not hesitate to contact this office.
Respectfully submitted,
INC.
~
Mark Bergman EG 1348
Chief Engin ering Geologist/
Office Manager
RR/MB
Distribution: (6) Addressee
8
~
I
I
I
I
I
, I
I I
I
I
I
I
I
I I
I
I
I
I
I
I
-Samol e
I
2
3
4
9
10
11
12
13
14
15
TABLE 1
Maximum Drv Density Test Results
Soil Descriotion
Dark brown, silty, fine to
coarse sand
Medium brown, fine to medium
sand
Medium brown, clayey, fine
to medium sand
Dark brown, clayey, fine to
medium sand; silt
5
6
Olive tan, silty, fine sand
Olive tan, fine to coarse
sand; clay
7
Medium brown, silty, fine
to coarse sand; gravel
8
Medium brown, fine to
coarse sand; silt
Tan olive, silty, fine sand
Tan brown, silty, fine to
medium sand
Tan, fine to medium sand,
trace of cl ay
Dark tan, clayey, silt; very
fine sand
Orangish brown, clayey,
medium to coarse sand
Tan brown, silty, medium
coarse sand
Orangish brown, sandy clay
with si It
Maximum Dry
Density (ocf)
131.0
124.5
133.0
131.0
124.5
129.0
129.5
134.0
114.0
129.5
118.5
113.0
130.5
129.5-
129.0
Project No. 11871347-05
Optimum
Moisture Content (%)
7.5
10.0
8.0
9.0
10.5
8.5
8.5
8.0
15.5
9.0
12.5
15.5
8.5
10.0
9.5
\D
,I
I
,I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
Project No. 11871347-05
TABLE 1 (continued)
Maximum Dry Density Test Results
Maximum Dry Optimum
Samole Soil Descriotion Density (ocf) Moisture Content (%)
16 Orange brown, fine to medium 126.0 10.5
sand, with clay
17 Medium brown, silty, medium 128.0 11.5
to coarse sand
18 Gray tan, fine to coarse 120.0 9.0
sand
19 Medium brown, medium to coarse 130.0 8.0
sand with grave)
\\
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
Project No. 11871347-05
TABLE 2
Summary of Field Density Tests
Exolanation of Summary of Field Density Tests
A.
Test No. 0001* Field Density Test by Sand-Cone
Method (ASTM DI556-82)
0001# Field Density Test by Nuclear-Gauge
Method (ASTM D2922-81)
0001^ Field Density Test by Dry-Cylinder
Method (ASTM D-2937-83)
B.
Test of: CF - Compacted Fill
FG - Finished Grade
NG - Natural Ground
SF - Slope Face
OG - Original Ground (Processed Natural Ground)
\z..
__ - - __u_
1
1 Project No. 11871347-05
Table 3
1
Exoansion Index Test Results - Tract 23101-2
1 Sample Initial Compacted Dry Final Volumetric Expansion Expansion
Location Moisture Density PCF Moisture% Swe 11 Index Potent i a 1
1
1 8.5 115.1 18.6 3.8 38 Low
1 2 12.4 100.6 31.4 11.3 113 High
27 8.0 117.8 15.2 0.0 0 Very Low
I 12 9.5 111.6 19.9 0.4 4 Very Low
34 9.2 113.1 18.0 2.2 22 Low
I 30 10.0 108.8 25.0 8.3 83 Medium
1 44 12.2 102.2 31.2 11.8 118 High
54 9.0 113.1 17.9 4.3 43 Low
I 62 10.5 107.8 25.8 7.8 78 Medium
74 9.5 111.4 19.8 4.2 42 Low
I 75 9.0 114.0 17.1 0.4 4 Very Low
1 77 10.3 108.3 21.0 2.7 22 Low
85 10.0 108.1 21.9 4.4 44 Low
1 98 9.5 111.6 24.6 7.1 77 Medium
101 71.5 103.4 28.9 9.2 92 High
I
I
I
I
, I'
,
I I- \~
I
1 Project No. 11871347-05
Table 4
I Lot Classification - Tract 23100
I Pre-soak Recommendation
Expansion Expansion Optimum Percent Moisture
Lots Index Potential Moisture% to deoth of saturation
1 1 38 Low 9.5 11.4 to 6"
2, 3 113 High 13.0 18.2 to 18"
, 1 4, 5 38 Low 9.5 11.4 to 6"
, 1 6, 7 113 High 13 .0 18.2 to 18"
8 0 Very Low 8.5 8.5 to 6"
I 9 - 12 4 Very Low 10.0 10.0 to 6"
13 - 23 22 Low 9.5 11.4 to 6"
I 24 - 26 83 Medium 11.0 14.3 to 12
I 27 0 Very Low 8.5 8.5 to 6"
28 - 30 83 Medium 11.0 14.3 to 12
I 31 - 34 22 Low 9.5 11.4 to 6"
35 - 44 118 High 13.0 18.2 to 18"
1 45 - 55 43 Low 10.0 12.0 to 6"
I 56 - 62 78 Medium 11.5 13.8 to 12"
63 38 Low 9.5 11.4 to 6"
1 64 113 High 13.0 18.2 to 18"
65 - 67 38 Low 9.5 11.4 to 6"
I 68 - 72 113 High 13.0 18.2 to 18"
I '73 - 74 42 Low 10.5 12.65 to 6"
75 4 Very Low 10.0 10.0 to 6"
1 76 - 82 22 Low 9.5 11.4 to 6"
83 - 84 118 High 13.0 18.2 to 18"
1
1 I~
I
I
I
I
II
I
I
I
I
I
I
I
I
I
I
I
I
I
1
Project No. 11871347-05
Table 4. continued
Lot Classification - Tract 23100
Pre-soak Recommendation
Expansion Expansion Optimum Percent Moisture
Lots Index Potential Moisture% to deoth of saturation
85 - 91 44 Low 11.0 13.2 to 6"
92 4 Very Low 10.0 10.0 to 6"
93 - 95 42 Low 10.5 12.6 to 6"
96 4 Very Low 11. 0 11.0 to 6"
97 - 100 77 Medium 10.0 13.0 to 12"
101 - 103 92 High 13.0 18.2 to 18"
104 77 Medium 10.0 13.0 to 12"
105 - 108 92 High 13.0 18.2 to 18"
\~
I
I
I
I
TABLE 5
Project No. 11871347-05
FOUNDATION DESIGN CONSIDERATIONS FOR EXPANSIVE SOILS
UNDERLYING ONE AND TWO-STORY RESIDENTIAL BUILDINGS
lone-~tory
Foot mgs
(See Note 1)
Expansi on Index
o - 20
Very Low Expansi on
Expansi on Index
21 - 50
Low Expans i on
Expans i on Index
51 - 90
Medi un Expans i on
Expansi on Index
91 - 130
High Expans i on
I
All footings 12"
deep. Footings
continuous. One
No. 4 rebar top
and bottom.
All footings 12"
deep. Footings
continuous. One
No. 4 rebar top
and bottom.
Exterior footings
1811 deep. Interior
footings 1211 deep.
One No. 4 rebar top
and bottom.
Exterior footings
24" deep. Interior
footings 1811 deep.
One No. 5 rebar top
and bottom.
Two-Story
Footings
I (See Not 1)
All footings 1811
deep. Footings
continuous. One
No. 4 rebar top
and bottom.
All footings 18"
deep. Footings
continuous. One
No. 4 rebar top
and bottom.
All footings 1811
deep. Footings
continuous. One
No. 4 rebar top
and bottom.
Exteri or foot i ngs 2411
deep. Interior foot-
ings 1811 deep. One
No. 5 rebar top and
bottom.
I Garage Door
Grade Beam
2411 deep. One No. 5
rebar top and bottom.
8U deep. One No.
4 rebar top and
bottom .
1211 deep. One No.
4 rebar top and
bottom.
18" deep. One No.
4 rebar top and
bottom.
I Living Area
Floor Slab
(See Note 2)
I
411 thick. 6x6.
10/10 welded wire
mesh. 211 sand
layer over 6 mi l
Visqueen moisture
barrier.
4" thick. 6x6-
10/10 welded wire
mesh. 211 sand
layer over 6 mil
Visqueen moisture
barrier.
4" thick. 6x6-
6/6 welded wire
mesh. 2" sand
Layer over 6 mi l
Visqueen moisture
barrier over 411
sand base.
4" thick:. No.4 rebar
lil 18" on center with
No. 4 dowels @ 1811 on
center with 211 sand
layer over 6 mil
Visqueen moisture barrier
over 4" sand base.
I Garage Floor
Slab
(See Notes
2 and 3)
411 thick. 6x6-
10/10 welded wire
mesh or quarter
slab.
4" thick. 6x6-
10/10 welded wire
mesh or quarter
slab.
4" thick. 6x6.
6/6 welded wire
mesh or quarter
slab. 411 sand base.
411 thick. No.4 rebar
lil 18" on center and
quarter slab. 411 sand
base.
I Presoaking
of Living
Area and
Garage Slab
I Soils
(See Note 4)
Soils moistened to
near optimum
moisture content to
a minimum depth of
611.
Soak upper 6" to
at least 1.2 X
optimum moisture
content or 2% above
optimum moisture
content, whichever
is greater.
Soak upper 12" to
at least 1.3 X
optimum moisture
content or 5% above
optimum moisture
content, whichever
is greater.
Soak upper 18" to at
least 1.4 X optimum
moisture content or
5% above optimum
moisture content,
whichever is greater.
I Notes:
* Expansion Index detennined in accordance with Test Method use 29-2..
1.
Minirnun footing width should be 12" for one-story bui ldings, 15" for two-story buildings, and 2411 for isolated spread
footings.
I
2.
Wire mesh and rebar should be placed at MtDHEIGHT of slab.
3. Isolate garage slab from perimeter footings. Slab sawcuts should be a minilTll.lll of 1 II deep.
I
4. It should be noted that presoaking may require an extended period of time to reach the recommended moisture content.
5. For expansion index over 130, special recommendations will be provided by the geotechnical consultant (as necessary)
based on actual field conditions.
I
6. All depths are relative to slab subgrade or finished ground surface, whichever is lower.
I
7. The above embedment and reinforcement considerations are minimum guidelines which may be increased at the discretion
of the structural engineer.
II
~
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
1
I
Project No. 11871347-05
Aooendix A
1. Leighton and Associates, Inc., 1990, Geotechnical Report of Rough Grading,
Tract 23101-1, Residential Development, Temecula, Riverside County,
California. Project No. 11871347-05, dated May 22, 1990.
2. ____, 1990, Interim Report of Rough Grading and Expansion Index Testing, Lots
1-51, Tract23101-1, City of Temecula, Riverside County, California.
Project No. 11871347-05, dated March 8, 1990.
3. , 1989, Geotechnical Review of Grading Plans and Additional Geotechnical
---- Investigation, Tracts 23100-3 and 23101-1, Rancho California, Riverside
County, California. Project No. 11871347-06, dated July 5, 1989.
4. , 1987, Preliminary Geotechnical Investigation, 253f Acres, Tentative
---- Parcel Map No. 22554, Margarita Village, Rancho California, California.
Project No. 6871347-01, dated September 24, 1987.
\1
I
I
I
I
I
I
I
I
I
'I
-I
I
I
-I
I
I
I
I
II
APPENDI X B
SLOPE MAINTENANCE GUIDELINES FOR HOMEOWNERS
TIPS. FOR-THE. HOMEOWNER
Homesites, in general, and hillside lots, in particular, need maintenance to
continue to function and retain their value. Many homeowners are unaware of this
and allow deterioration of their property. In addition to his own property, the
homeowner may be subject to liability for damage occurring to neighboring
properties as a result of his negligence. It is therefore important to
familiarize homeowners with some guidelines for maintenance of their properties
and make them aware of the importance of maintenance.
Nature slowly wears away land, but human actiyities such as construction increase
the rate of erosion 200, even 2,000 times that amount. When we remove vegetation
or other objects that hold soil in place, we expose it to the action of wind and
water and increase its chance of eroding.
The following maintenance guidelines are provided for the protection of the
homeowner's investment, and should be employed throughout the year.
a) Care should be taken that slopes, terraces, berms (ridges at crown of slopes),
and proper lot drainage are not disturbed. Surface drainage should be
conducted from the rear yard to the street by a graded swale through the
sideyard, or alternative approved devices.
b) In general, roof and yard runoff should be conducted to either the street or
storm drain by nonerosiye devices such as sidewalks, drainage pipes, ground
gutters, and driveways. Drainage systems should not be altered without expert
consultation.
c) All drains should be kept cleaned and unclogged, including 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, waterlines, etc. or bypassing of drains should be
repaired as soon as possible.
e) Animal burrows should be filled since they may cause diversion of surface
runoff, promote accelerated erosion, and eyen trigger shallow soil failures.
Slopes should not be altered without expert consultation.
homeowner plans a significant topographic modification of the lot
qualified geotechnical consultant should be contacted.
g) If plans for modification of cut, fill, or natural slopes within a property
are considered, an engineering geologist should be consulted. Any
oversteepening may result in a need for expensive retaining devices.
Undercutting of the bottom of a slope might possibly lead to slope instability
or failure and should not be undertaken without expert consultation.
f)
Whenever a
or slope, a
\~
I
I
I
I
I
I
I
1
I
I
1
I
I
I
I
I
I
I
I
...
h) If unusual cracking, settling, or earth slippage occurs on the property, the
homeowner should consult a qualified soil engineer or an engineering geologist
immediately.
i) The most common causes of slope erosion and shallow slope failures are as
follows:
o Gross neglect of the care and maintenance of the slopes and drainage
deyices.
o Inadequate and/or improper planting. (Barren areas should be replanted as
soon as possible).
o Excessive or insufficient irrigation or diversion of runoff over the slope.
o Foot traffic on slopes destroying yegetation and exposing soil to erosion
potential.
j) Homeowners should not let conditions on their property create a problem for
their neighbors. Cooperation with neighbors could prevent problems and also
increase the aesthetic attractiveness of the property.
Winter Alert
It is e~pecialJY important to "winterize" your property by mid-September. Don't
wait until spri~g to put in landscaping. You need winter protection. Final
landscaping can be done later. Inexpensiye measures installed by mid-September
will give you protection quickly that will last all during the wet season.
o Check before storms to see that drains, gutters, downspouts and ditches are
not clogged by leaves and rubble.
o Check after major storms to be sure drains are clear and yegetation is holding
on slopes. Repair as necessary.
o Spot seed any bare areas. Broadcast seeds or use a mechanical seeder. A
typical slope or bare areas can be done in less than an hour.
o Give seeds a boost with fertilizer.
o Mulch if you can, with grass clippings and leayes, bark chips or straw.
o Use netting to hold soil and seeds on steep slopes.
o Check with your landscape architect or local nursery for advice.
o Prepare berms and ditches to drain surface runoff water away from problem
areas such as steep, bare slopes.
o Prepare bare areas on slopes for seeding by raking the surface to loosen and
roughen soil so it will hold seeds.
\1\