HomeMy WebLinkAboutGeology and Geotechnical Engineering Investigation - GEO General - 6/30/2000 American Engineering Corporation
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Sweetwater Development
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Geology and Geotec nica
Engineering Investigation
June 30, 2000
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repured for:
Jack Johnson
P.O. Box 1119
Consulting Engineers Belfair, WA 98528
Credtive Solutions. . .
Superior Service. AEC Job 92039
Sweetwater Development
Belfair, Washington
Geology and Geotechnical
Engineering Investigation
June 30, 2000
prepared for:
Jack Johnson
P.O. Box 1119
Belfair, WA 98528
AEC Job #2039
Sweetwater Development
Belfair, Washington
Geology and Geotechnical
Engineering Investigation
June 30, 2000
prepared for:
Jack Johnson
P.O. Box 1119
Belfair, WA 98528
by:
American Engineering Corporation
4032 148" Avenue NE
Redmond, WA 98052
(425) 881-7430
(425) 881-7731 fax
AEC Job #2039
GEOLOGY& GEOTECHNICAL ENGINEERING INVESTIGATION
SWEETWATER CENTER DEVELOPMENT
Table of Contents
I. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... . . . . . . . . . . . . . . 1
A. General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
B. Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
C. Site Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
D. Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
II. SITE DESCRIPTION AND INVESTIGATION . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . .. . . . 2
A. Surface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
B. Subsurface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
C. Groundwater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
D. Seismicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
E. Slope Stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
III. CONCLUSIONS AND RECOMMENDATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
A. General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
B. Earthwork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
C. Foundation Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
IV. CONSTRUCTION OBSERVATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . . . . . . . . . . 12
V. REPORT PREPARATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. . 12
FIGURES AND TABLES
Figure 1. Vicinity Plan
Figure 2. Site Plan
Figure 3. Typical Slab—on—Grade Design Detail
Figure 4. Typical Retaining Wall Detail
APPENDICES
Appendix A. Boring Logs and Laboratory Test Data
Appendix B. Guide Specification for Site Earthwork
Appendix C. Rockery Guidelines
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GEOLOGY&GEOTECHNICAL ENGINEERING INVESTIGATION—SWEETWATER CENTER DEVELOPMENT
I. Introduction
A. General
This geology and geotechnical engineering report presents the results of our subsurface
investigation, laboratory testing of fill materials, evaluation of site conditions, and recommendations
regarding foundation preparation. The purpose of this study is to provide foundation design parameters for
the three unit commercial development proposed for the site.
Preliminary work has been done on the site by others and a grading and paving plan, drainage plan,
and architectural plans have been prepared. Four hand dug test pits were excavated in the earlier work.
Six backhoe excavated test pits were excavated for this phase of the project.
B. Location
The proposed Sweetwater Center is located on the west side of Highway 3 about one half of a mile
South of the center of Belfair(Figure 1). The commercial address of the gas station to the northeast of the
property is 22691 Hwy 3. Access to the site is directly off of Hwy 3 on a down slope driveway from a
generally straight section of Hwy 3. There is at least 500 feet of line-of-sight in both directions on Hwy 3.
C. Site Description
The site is located on a west facing slope that descends from elevation (E1) 48 to E1 38 across the
110 feet of property width. The site has been cleared of timber and is presently thickly covered by grass
and blackberries . Some fill has been placed about half of the site.
There is a small stream flowing across the site from the upslope area above Hwy 3. The stream
flows directly into the creek located about 50 feet northwest of the structures. The stream will have to be
diverted or channeled around the development.
The proposed building site is located on about 0.5 acre of a larger parcel of unknown size. The
proposed structures considered are two one story commercial structures, one two story commercial
structure, parking area, and detention pond. This report addresses only the building foundation area,
subsurface conditions and recommendations for foundation stabilization. We do not anticipate the use of
piles, retaining walls or other unusual supporting structures.
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D. Limitations
This report has been prepared in accordance with generally accepted geotechnical engineering
practices, and in accordance with our agreement with Mr. Jack Johnson for the specific application to the
commercial development. In the event there are any changes in ownership, design, or location of the
proposed structures, or if any future additions are planned, the conclusions and recommendations contained
in this report shall not be considered valid unless 1)project changes are reviewed by American Engineering
Corporation, and 2) the conclusions and recommendations presented in this report are modified or verified
in writing. Reliance on this report by others must be at their own risk unless we are consulted with regard
to the use or limitations of this information. We cannot be responsible for the impact of any changes in
environmental standards without further consultation. We can neither vouch for the accuracy of
information supplied by others nor accept consequences for non—consulted use of segregated portions of
this report.
II. Site Description and Investigation
A. Surface
The proposed three commercial structures will each have 3,000 to 4,000 square feet footprints. Final
floor elevations have been determined to be about E 145 to 45.5. At this elevation, approximately 7 feet of fill
will be required along the northwest side of the structures. About two feet of fill will be needed on the
southeast side of the buildings. The fill will be placed directly on the existing regraded surface. As we are
recommending a surcharge application, it will not be necessary to clear and strip the existing surface.
B. Subsurface
Two series of subsurface investigating have been performed on the site. American Engineering
logged six test pits (Figure 2, site plan). The previous work consisted hand dug test pits. The soil
descriptions are similar but the greater depth of the AEC study identified loose sandy and soft clayey soils.
These soils raise concern that there may be up to four feet of settlement—prone soil under the building site.
We do not believe that the soils are prone to liquefaction as there is a moderate to high percentage of clay
in the observed soils. Subsurface investigations in the vicinity indicate that the deeper soils are coarsely
granular and very dense-precluding the possibility of liquefaction at a greater depth.
C. Groundwater
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Groundwater was encountered in the test pits at depths varying from two to six feet. The actual
depth to water did not seem to be controlled by the proximity to the small surface stream crossing the
property. The creek located west of the project appears to control the groundwater gradient. Inflow rates
in the west test pits were very high compared to the eastern test pits. The test pits were not open long
enough for water levels to stabilize. The identified depths were where wet conditions were first observed
during excavation.
A previous report identified several wells in the vicinity that produce groundwater for domestic
use. We anticipate that there are several non—registered wells in the vicinity as well. An evaluation of the
detention storage and discharge system is not a part of this report.
The high groundwater table raises questions regarding the potential for liquefaction of soils during
earthquakes. This potential will be addressed in the following sections:
D. Seismicity
Earthquake intensities vary depending upon the magnitude of the earthquake and the distance of the
project site from the epicenter or causative fault. This site could be subject to substantial seismic events if
past history represents the regional pattern. Four earthquakes between 5.5 and 7.0 magnitude have been
centered within 30 miles south and southwest of the site. Some of these earthquakes caused significant
damage in the Olympia and Seattle area in 1949 and 1965, respectively. One 5.5 magnitude earthquake
occurred within the past 3 years near Monroe. Minor damage was reported. A more recent earthquake of
magnitude 5.8 occurred in 1999 centered near Montesano. This event caused major damage in Montesano
and Aberdeen and severely shook the Belfair area. The distance from the epicenter of this event to the site
was 50 miles.
Faulting
The primary tectonic feature located in the Pacific Northwest and dominating the region's
seismicity is the Juan de Fuca Subduction Zone located approximately 70 kilometers below the earth's
surface. The surface expression is located approximately 150 to 200 kilometers west of Seattle. This zone
is expected to produce earthquakes of a magnitude of 8.0 or larger with return periods of around 300 to
500 years. This earthquake magnitude and return period has been interpreted based on features observed
along the Pacific Coast. To date these parameters are subjective and the subject of further studies. The
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distance to a potential hypocenter under the site is sufficiently great to reduce the peak particle acceleration
onsite to that anticipated by the UBC.
Minor faults have been mapped in the bedrock exposed west of Belfair. No local faults have been
mapped in the glacial sediments located near the site. The earthquake concentrations of the past in the
Olympia area and south Olympic Mountains are likely to impact site conditions and structures. These
events have a return period of about 20 years and have yet to have caused significant damage in this area.
It is our opinion that the UBC design requirements are adequate to protect structures on this ste.
Liquefaction
Generally, soils that are susceptible to liquefaction are loose, saturated, uniformly graded,
fine—grained sand that lies within 60 feet of the ground surface. The bearing soils identified onsite consist
of stiff clay and dense to very dense gravelly sand in the saturated zone. Water well logs in the area
indicates very stiff clay and very dense sand and gravel from the surface to below 60 feet. The ease by
which the test pits caved caused concern for a potential for liquefaction. However, the several site
investigations performed in the area, granular and dense nature of the soil and the absence of histol ical
references to liquefaction indicate that the potential is low. We do recommend that the structural fill be
extended beyond the footprint of the structure by a minimum of 10 feet, the foundation slab be reinforced
and wall/roof ties be reinforced to stiffen structure.
Lurching
The present site slopes gently to the northwest at less than 10 percent. There is no risk for slope
failure. No slope edges are present in the area that amplify seismic vibrations.
It is likely that the structural fill will be placed on two different subsoils that may respond to
vibrations differently. This nonharmonic response could result in cracking of the fill if shaking is
sufficiently intense. It must be noted that the historic earthquakes are of short duration and not of very high
accelerations; therefore, the suggested mitigation measures indicated in the liquefaction section should be
adequate for construction.
Seismic Design Parameters
The Uniform Building Code (UBC) Seismic Zonation Map (1994) places the site in Seismic Zone
3. The UBC recommends that the seismic zone factor(Z) be 0.30. The site coefficients are: soil type"Sc"
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a stiff to soft soil profile that VS 1200 to 2500fps. The seismic source type is B and the near source factor
(N„and NJ. Bedrock is located more than 300 feet below the surface in this location.
It is our opinion that the seismic stability of this site is suitable for the construction of a one and two
story commercial structures taking into due consideration the potential for amplification of accelerations
from an earthquake at a distance of 30 to 50 miles. Ii is our opinion that the distance to historic earthquake
centers is sufficiently great to allow the use of 0.20g for the 100-year event. All site parameters are within
the UBC seismic design requirements and those requirements should be used.
E. Slope Stability
There are no steep slopes on or near the site that could increase the risk to the development. Fill
slopes should be maintained at 2:1 (H:V) to minimize sloughing if the proposed borrow of gravelly sand is
to be used. The slopes should be revegetated as soon as possible after construction.
III. Conclusions and Recommendations
A. General
It is our opinion that the site is suitable for construction of the proposed three building commercial
complex and the related siteworks from a geotechnical engineering standpoint. The presence of stiff clay and
dense gravelly sand below one to four feet is the primary consideration for site suitability. If a structural fill
and surcharge are used to stabilize the site, no excavation of the existing topsoil is required. Care must be
taken where utilities cross the fill/surcharge zone from off-site as differential settlement may occur.
Use of a structural fill pad will allow the use of standard, perimeter spread footings bearing on the
structural fill. We recommend that these footings have a minimum of two feet of compacted structural fill
underneath and be embedded a minimum of 18-inches below final grade to minimize the effects of ground
frost.
We recommend that our firm review the final design and specifications to confirm that the
earthwork and foundation recommendations presented in this report have been properly interpreted and
implemented. This report is based on the grading paving plan provided us. We also recommend that a
representative from American Engineering Corporation be present onsite during fill operations to observe
the compaction and distribution of fill. We can assume no responsibility for the misrepresentation of our
recommendations if we do not review the plans and specifications, and monitor the earthwork.
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The conclusions and recommendations presented in this report should be incorporated in the design
and construction of the project to minimize any soils and/or foundation-related problems. Detailed
earthwork and foundation recommendations for use in design and construction of the project are presented
in the following sections.
B. Earthwork
1. Clearing and Site Preparation
The commercial structure footprints should be leveled and cleared of debris. Tall grass and vines
should be mowed. Tree stumps should be removed but the organic debris left can be covered with fill. A
maximum of one foot of fill should be spread across the building pads without compaction. This layer is to
be followed by 8-inch lifts compacted to 95 percent of maximum dry strength.
Z Temporary Excavations
Foundation excavation depths, including utility trenches, should comply with local, state, and
federal safety regulations. Specifically, the current OSHA Health and Safety Standards for excavations, 29
CFR Part 1926, should be followed. We understand that these regulations are to be strictly enforced,
and if they are not closely followed,the owner and contractor could be liable for substantial penalties. The
contractor's "responsible person as defined in 29 CFR Part 1926" should evaluate the soil exposed in
excavations as part of the contractor's safety procedures.
3. Subgrade Preparation
Structural fill should be placed on the one foot of uncompacted fill placed on the mowed,
undisturbed surface. This initial fill should be track rolled to take the haul truck traffic. All placed fill
should be leveled and extend a minimum of 10-foot outside of the respective building footprint. All fill
must be moisture controlled to ensure maximum compaction.
4. Engineered Fill Layer
Two Modified Proctor samples were obtained from nearby borrow pits (Appendix B). All fill from
- these pits shall be compacted to a minimum of 95 percent of the maximum dry strength. Fill shall be
placed in lifts of 8 inches uncompacted, moisture controlled, and rolled to maximum density. Oversize
material (76 inches) shall be removed and the fill should not contain more than 15 percent of rock over 2.5
inches nominal diameter. We recommend that the fill be constructed a minimum of 4 feet thick under the
shallowest part of the structure.
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Accordance with Section III.B.3, Subgrade Preparation. Imported fill shall be compacted in
accordance with Section III.B.6, Compaction. The conventional, continuous spreadfootings should be
placed on the excavated and prepared surface and have a minimum embedment below final, finish grade of
18 inches.
S. Fill Material
The Corbit Pit sample is likely to be used to fill the site. The Modified Proctor results are provided
in Appendix B. No onsite soil shall be used as structural fill. Any excavated soils that do not meet the
requirements of structural fill should not be used or mixed with any fill material, and should be disposed of
offsite.
Acceptable fill shall consist of granular soils that are placed in accordance with the requirements
provided in Sections III.B-3,4,5, and 6. All fill placed at the site including onsite soil should not contain
rocks or lumps larger than 6 inches in greatest dimension with not more than 15 percent larger than 2.5
inches. In addition, imported fill should be predominantly granular with a plasticity index (PI) of 12 or less.
Imported structural fill will be observed and tested using Modified Proctor Compaction tests
(Appendix B) to determine the required compaction efficiency to attain the required 95 percent of
maximum dry density. All fill material should be placed at, or slightly above the optimum moisture content
and compacted to a 95 percent of maximum dry density, The quality of the structural fill will determine the
number of compaction tests required during fill construction.
6. Compaction
All structural fill and slope backfill should be compacted to at least 95 percent relative compaction
as determined by ASTM Designation D1557-78. Fill material should be spread and compacted in lifts not
exceeding eight inches in uncompacted thickness. Soils not passing the minimum standards identified in
these recommendations will be rejected, excavated, and replaced. Compaction testing of the fill should be
performed in every 2-foot lift and tests should be every 50 feet across each fill layer.
7. Trench 3ackfill
Utility trenches can be backfilled with the imported fill placed in lifts of approximately 6 inches in
uncompacted thickness. Thicker lifts can be used provided the method of compaction is approved by a
representative from American Engineering Corporation and the required minimum degree of compaction is
achieved.
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The backfill material should be compacted by mechanical means to a minimum degree of
compaction of 90 percent. Imported sand can be used for backfilling trenches provided it is compacted to
at least 95 percent and sufficient water is added during the trench backfilling operations to prevent the soil
from bulking during compaction. The upper 3 feet of trench backfills under slab and pavement areas
should be compacted to at least 95 percent relative compaction for onsite soils and where imported sand
backfill is used.
8. Surcharge
The soft, shallow soils have raised concern for the potential of excess settlement under the
structures. Settlement can be mitigated by surcharging the proposed foundation fill. The proposed
surcharge loading is based on the possible live and dead loading of the structures. We have assumed 40
pounds per square foot load for both live and dead loads and 40 pounds for the second floor this is a total
of 120 pounds per square foot for the two story structure. The use of the Corbit Pit gravelly sand
compacted to 90 percent maximum dry density(100 pcf) in a three foot thick surcharge will be the
equivalent of the building load plus a safety factor of 2.
This surcharge should be left on the site until the two prior readings of the settlement gages show
less than 10 percent deflection of the previous reading. This usually takes from 30 to 90 days. I strongly
recommend placing settlement gages and surveying weekly.
Upon attainment of maximum settlement, the surcharge can be removed and placed as fill for the
parking lot. Foundation footings can be cut into the building pad. Slab-on-grade flooring should be poured
on the fill surface with a capillary break of 4 inches of crushed rock, visqueen vapor barrier(10 mil), and 2
inches of clean moist sand to aid concrete finishing and curing(Figure 3).
9. Settlement Gages
The settlement gages consist of an 18-inch or 24 -inch square steel plate with a#4 rebar welded to
the center and a one-inch diameter PVC sleeve over the 44 rebar. Each gage should be placed on existing
native soils. The plat and top of bar elevation has to be surveyed prior to fill. The top of bar should be
measured weekly to determine the extent and rate of settlement. The gages should be located at the comer
of each structure.
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10. Drainage
Onsite soils have been classified using the Unified Soils Classification System(USCS). The
original soils on the surface of the site appear to have been stripped sometime prior to this stage of work.
Below 2 to 4 feet the soils are sandy with clay and gravel. The shallow water table caused the test pits to
cave readily. By filling the site, structures will be raised above the present water table and storm runoff
from the site will be improved. Footing drains are not necessary for fills of this nature unless the County
Ordinance mandates their use. Perimeter structural drainage is best facilitated by sloping the perimeter fill
away from the structure and tightlining the downspout system away from the fill.
Water should not be allowed to pond in any areas where foundations, slabs, or pavements are to be
constructed. The structural fill and surcharge should be sloped to drain during the surcharge process. All
excavations can be sloped towards one or more shallow sump pits. The collected water should then be
diverted to a positive and permanent point of discharge.
10.1 Construction Drainage
Protection of the vegetated area and the water quality of the nearby creek must be considered
during construction. Silt fences shall be installed on the downslope margins of all construction areas.
Straw bales will be staked into drainage swales to impede silt-laden runoff. We recommend that all
construction runoff be infiltrated adjacent to the toe of the fill slope or discharged to the detention pond.
Steeply drainage swales will require riprap lining to reduce flow velocities to non-erodible levels. Details
of these drainage requirements should be provided with the drainage and erosion control plans.
10.2 Drainage Measures
Long—term drainage measures should include (1) grading, (2)slab moisture barriers. Design of a
stormwater detention system is not part of this study. Each of these is discussed below.
10.2.1 Grading
Positive surface gradients should be provided adjacent to the building to direct surface water away
from foundations and slabs toward suitable discharge facilities. We recommend that the ground be sloped
at a minimum 3 percent gradient for a distance at least 10 feet away from the structure. Similarly, roof
downspouts should be connected to suitable discharge facilities. Ponding of surface water should not be
allowed adjacent to the structure or on pavements.
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10.2.2 Under-Slab Moisture Barriers
Under-slab moisture barriers will be necessary on this site because of the wet conditions and
shallow groundwater. We recommend that the slab areas be graded, compacted, and covered with crushed
rock to form a capillary break and then a moisture barrier of at least 10 ml visqueen and about 2 inches of
moist sand to ease the installation of the concrete slab (Figure 3).
11. Construction Daring Wet Weather Conditions
If construction proceeds during or shortly after wet-weather conditions, the moisture content of
onsite soils will be above optimum. Consequently, subgrade preparation, placement and/or reworking of
onsite and structural fill will not be possible. Alternative wet-weather construction recommendations can
be provided by American Engineering Corporation in the field just prior to construction, if appropriate.
12. Guide Specifications
All earthwork should be performed in accordance with the Guide Specifications for Site Earthwork
presented in Appendix B. Rockery construction guidelines are provided in Appendix C. These specifications
are general in nature. Final specifications should incorporate all recommendations in this report.
C. Foundation Support
1. Spread Footing
Foundation areas should be prepared as described in Sections IH.13-3 and 1113-4 of this report.
Any conventional footings can be designed on the basis of the following criteria:
• Allowable bearing pressure on the structural fill, including all dead and live loads . . . . . 2,000 psf
• A one-third increase in the bearing capacity can be used when considering short term transient
loads.
• Minimum depth of perimeter footing below adjacent final exterior grade to account for frost
penetration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18inches
Continuous footing should be designed with adequate top and bottom reinforcing to provide
structural continuity and permit spanning of local irregularities. We recommend that the footings be a
minimum width of 18 inches.
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Footings located adjacent to other footings or utility trenches should bear below an imaginary 1.5:1
(horizontal to vertical)plane projected upward from the bottom edge of the adjacent footings or utility
trenches.
1. Slab—on—Grade
Slab-on-grade floors can be used with conventional shallow foundations provided that interior slab
foundation zone is placed on structural fill or crushed rock. Slab-on-grade subgrade surfaces should be
proof-rolled to provide a smooth unyielding surface for slab support. Slab reinforcing should be provided
in accordance with the anticipated use and loading conditions.
Because the slab may be supported on the engineered fill, slab damage, in the form of warping,
cracking, and separation caused by differential settlement, may occur unless reinforcing is designed by the
structural engineer. The slab will then require periodic maintenance. We recommend that the slab be
reinforced with 94 rebars, 18 inches on center. However, the slab should be designed by a structural
engineer for the anticipated use and loading.
3. Settlement
We recommend that the foundation be placed on a minimum thickness of 3.5 to 4.0 feet of structural
fill. Foundations bearing directly on structural fill that is unsurcharged may experience settlement of six to
eight inches across the width of the structure. The use of surcharge is expected to reduce this settlement to
less than one inch of differential settlement. To minimize the differential settlement, we have recommended
that the structures be placed in a minimum fill thickness of 3.5 to 4.0 feet.
4. Resistance of Lateral Loads
Lateral load resistance on any retaining walls can be developed friction between the foundation
bottom and the supportive subgrade. The subgrade will be clayey sand. A friction coefficient of 0.4 is
considered applicable for the underlying soils. As an alternative, a passive resistance and active fluid
pressure should be as follows:
• Passive pressure, Equivalent Fluid Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300 pcf
• Active pressure, Equivalent Fluid Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 pcf
If the foundation footings are poured neat against the soil, the friction and passive resistance can be
used in combination. We assume that the top of any retaining wall will have a flat surface. An equivalent
soil surcharge of two feet is recommended.
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S. Retaining Wall
A retaining wall is expected to be requires between the west side of Hwy 3 and the project's
parking lot. The proposed wall design varies up to 8 feet high. The proposed wall is a cantilever structure.
The subdrainage system schematic is provided in Figure 4 and is shown on the building plans.
IV. Construction Observation
The analysis, designs,opinions, and recommendations submitted in this report are based upon our site
observations, knowledge of the site and experience with projects within the area. Variations of subsurface
conditions from those analyzed or characterized in the report are possible and may become evident during
construction. In that event, it may be advisable to reevaluate certain analyses or assumptions.
We recommend that our firm be retained to provide geotechnical services during site grading,
foundation excavation, subgrade preparation and backfilling to observe compliance with the design
concepts, specifications, and recommendations presented in this report. Our presence will also allow us to
modify the design if unanticipated subsurface conditions are encountered.
V. Report Preparation
This report was prepared by R.J. Bielefeld, Engineering Geologist. This report was prepared
under the supervision of a registered professional engineer of the State of Nash
4 GUND�
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American Engineering VICINITY MAP
Corporation
SWEETWATER CENTER
4032 14811 Avenue NE a Redmond•WA 98052 Project N° Date Figure
Tel.(425)881-7430• Fax.(425)881-7731 2039 June 12, 2000 N4
Email: —aec msn.com
OCT-22-01 10 :30 AM AES CONSULTANTS INC 360 692 8927 P. 01
AES
CONSULTANTS, INC. PROFESSIONAL LAND SURVEYORS
P.O.BOX 930 - 3472 N.W.LOWELL"OID TOWNE"
SILVERDALI;,WASHINGTON 98383
360.6924400 - FAX 360.692-8927
October 22, 2001
Jack Johnson
Jack Johnson Construction Inc.
PO Box 1119
Beifair, Wa 98523
RE: SWEETWATER CENTER, BELFAIR, WA
Dear Jack;
At your request, we monitored the elevation plates for the pre-loading required for the above
project.
The first monitoring was done on September 9, 2000. Our second monitoring was done on
October 30, 2000. The final monitoring was cone on March 3, 2001. Elevation change was less
than 0.01 foot on all monitoring points.
PIease call should you have any further questions.
Sincerely,
Steve Ottmar PLS ,
D
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GENERAL 17ESTING LABORATORIOES9 INC.
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SLAB-CV-GRADE
a 2" SAND
AP°RCXIMA 1t. FINISHED
GRADE 6" CCURSE GRAVE: BASE
2" SCIL LAYER, --� UEEN UEMEzANE
C i. pi
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•i• • .v• �1 • • • 6d d ,• /
NATIVE =OIL,
iFOOTING — UNDIS uRS��
NOTE:
THE SOIL SHOULD EE COMPACTED TO A RELATIVE
COMPACTION OF a5 PERCENT. NO7 TO SCALE
American t:,+ytn«.s P,anM„ ,,,, TYPICAL SLAB—ON—GRADE PLAN
Engineering 4032„an, A...,v.E
C orporation R"1onL "A 9=
SWEETWATER CENTER
a (425) aet-7430 Fm(425)=I—m1 aa0.E'nUMM o�TE FIGURE2039 . 6-3D-00 3
i
IMPERVIOUS SOIL
MIRA DRAIN OR WATER FiNPRO
18" MIN. C C
REiNFORCEn CCNCREitt STEM 'N,4LL
0
a
H
7/8" TO 1 1%s" WASHED GR.'.VEL
4
�v O
H-18"
o
4
o ; I
�- SLAB—ON—GRADE
FLOOR
4" PERFORATED PVC
DRAIN PIPE o o o
REINFORCED CONCRE;E FOOTING
NOT TO SCALE
American Eaginoen . Planners . Surveyors TYPICAL RETAINING WALL DRAIN
E ngineering 4= 14eN A—4Z
C orporation R'0innondL Y1A9°0ss SWEETWATER CENTER
PHONE(425) a01-7430 fat(423) SM-7731 PROJECT NUMBER OATS MUM
2039 6-30-00 �-
Appendix A
UNIFIED SOIL CLASSIFICATION SYSTEM
Major Divisions 1grf I Itr I Description Major Divisions �grf Itr Description
�W Well-graded gravel or gravel-sand Inorganic silt and very tine sand.
mixtures,little or no fines ML rock flour,silty or clayey tine sand
Silts or clayey silt with slight plasticity
Gravel Poorly-graded gravel or gravel
,�d Inorganic clay of low to medium
+..110 GP sand mixtures, little or no fines Clays CL plasticity,gravelly clay, sandy
And -ft clay, silty clay,lean clay
Gravely Silty ravel, ravel-sand-silt LL < 50
I GM g g Organic silt and organic silt-clay of
Soils mixtures Fine OL low plasticity
Grained
GC Clayey gravel,gravel-sand-clay Solis Inorganic silt,micaceous or
Coarse mixtures M diatomaceous fine or silty soil,
Silts elastic silt
Grained
Soils S`V an or gravelly sand
, And Inorganic clay of high plasticity,
little or no tines Clays CHI fat clay
Sand LL > 50
SP Pooriv-graded sand or gravelly Organic clay of medium to high
And sand,little or no fines OH plasticity
Sandy
Soils SM�Silty sands.sand-silt mixtures
Highly Organic • Pt Peat and other highly organic
.
SC lClavey sand.sand-clay mixtures Soils soils
SYMBOLS
Standard penetration split-spoon sample Blank casing
® E Modified California(Potter)sample Screened casing
Grab(Cuttings)sample a Cement grout
Water level observed in boring ® Bentonite
EzStable water level in monitoring well a Filter pack
Sands and Gravels I Blows per Foot Silts and Clays Blows per Foot
Very Loose I t 0-4 Very Soft I 0-2
Soft 2-4
Loose 4- 10
IMedium Dense ( 10-30 Firm 4-8
Stiff I 8-16
Dense 30-50 Very*Stiff 16-32
Very Dense I Over 50 Hard I Over 32
Notc(1): Penetration resistance values are recorded as the number of blows of a 140-pound hammer falling 30-inches
required to drive a sampler through the last 12 inches of an I8-inch drive. Blow count for samples obtained using a
Modified California sampler(indicated by an asterisk)should be multiplied by a factor of 0.8 to obtain equivalent
standard penetration resistance values.
Note(2): The lines separating strata on the logs represent approximate boundaries only. No warranty is provided as to the
continuity of soil strata between borings. Logs represent the soil section observed at the boring location on the date
of drilling only.
American Engineering Corp. TEST PIT LOG LEGEND
SWEETWATER CENTER
4032 141?Avenue NE • Redmond•WA 98052
Tel.(425)881-7430• Fax.(425)881-7731 PROJECT NO. DATE FIGURE
I 2039 JJune 12, 2000 No B-1
Excavation Method: Case Backhoe Surface Elevation: — Logged By: R.J. Bielefeld, CEG
Depth to Groundwater: None Date Excavated: April 26, 2000 Weather. Overcast, warm
DESCRIPTION&CLASSIFICATION
SAMPLE TEST RESULTS AND COMMENTS
DESCRIPTION&REMARKS DEPTH SOIL TYPE CONSISTENCY NO.
(inches)
0.0-45.0: Sand with clay and gravel; No root topsoil profile
Fill, yellow brown, wet """"
6.....
....42....
Sc—Sp Very dense
....24....
....30....
....36•••-
....42....
45.0-51.0: Topsoil; brownish black, wet, OH Soft
organic ..48
51.0-75.0: Sand; 30%clay, 20% gravel,
wet, reddish yellow brown 54
Sc Very dense
....60....
....66....
V water table
75.0-81.0: Gravel; dark yellow brown, Gp Very dense Seepage
sandy, wet ""78....
Bottom of test pit=81"
Backfilled
....90....
....96....
.....102...
American Engineering TEST PIT LOG
Corporation
SWEETWATER CENTER
PROJECT NO. DATE TEST PIT
4032148th Avenue NE•Redmond WA 98052 NO. TP-1
Tel.(425)881-7430 9 Fax.(425)881-7731 2039 June 22,2000
Excavation Method: Case Backhoe Surface Elevation: — Logged By: R.J. Bielefeld, CEG
Depth to Groundwater: None Date Excavated: April 26, 2000 Weather: Overcast, warm
DESCRIPTION&CLASSIFICATION
SAMPLE TEST RESULTS AND COMMENTS
DESCRIPTION&REMARKS DEPTH
E T SOIL TYPE CONSISTENCY NO.
(in0.0-12.0: Topsoil; Root zone; clay, dark Grass covered
brown, moist Cl Soft to Stiff
....6.....
....42----
12.0-48.0: Sand, clayey; with gravel,
gravel becomes more abundant with ............
depth ....48....
Sc Very dense
....30....
...36....
....42....
....48....
Bottom of test pit=48"
Backfilled
....60....
....66....
...72....
.....78
...84....
....90....
....96....
....102...
American Engineering TEST PIT LOG
Corporation
-wAAL SWEETWATER CENTER
PROJECT NO. DATE
4032 148th Avenue NE•Redmond a WA 98052 TEST PIT TP_2
Tel.(425)881-7430•Fax.(425)881-7731 2039 June 22,2000 NO.
Excavation Method: Case Backhoe Surface Elevation: — Logged By: R.J. Bielefeld, CEG
Depth to Groundwater: None Date Excavated: April 26, 2000 Weather: Overcast, warm
DESCRIPTION&CLASSIFICATION
SAMPLE TEST RESULTS AND COMMENTS
DESCRIPTION&REMARKS DEPTH SOIL TYPE CONSISTENCY NO.
(inche0.0-54.0: Sand, gravelly; with 20-30%
clay, dark reddish brown, wet Sc—Sp Dense
.....6.....
...42....
....48....
Looks like fill on top of the water table
.....24
Gets wetter with depth
Bearing capacity 2000 psf
....36....
wet y= 110
....42....
............ v
....48....
....54....
Bottom of test pit=54"
Backfilled
....66....
....72....
...fig....
...S4....
....90....
....96....
..402...
American Engineering TEST PIT LOG
Corporation
SWEETWATER CENTER
a` PROJECT NO. DATE TEST PIT
4032 148th Avenue NE•Redmond•WA 98052 NO. TP-3
Tel.(425)881-7430•Fax.(425)881-7731 F 2039 June 22, 2000
Excavation Method: Case Backhoe Surface Elevation: — Logged B : R.J. Bielefeld CEG
Ex gg y ,
Depth to Groundwater: None Date Excavated: April 26, 2000 Weather: Overcast, warm
DESCRIPTION&CLASSIFICATION
SAMPLE TEST RESULTS AND COMMENTS
DESCRIPTION&REMARKS (i PTH SOIL TYPE CONSISTENCY NO.
0.0-48.0: Fill; Sand, clayey;with gravel,
yellow brown, wet
....6.....
....42....
48....
Sc Dense
Get wetter with depth
....30....
Caving
....36....
Saturated zone is soft o
Lot of water
....54....
....60....
....66....
....72....
..--.8....
....84....
....90....
...96....
---402...
American Engineering TEST PIT LOG
Corporation
--+�'�� SWEETWATER CENTER
% - PROJECT NO. DATE TEST PIT
4032 148th Avenue NE• Redmond WA 98052 NO. TP-4
Tel.(425)881-7430•Fax.(425)881-7731 2039 June 22,2000
Excavation Method: Case Backhoe Surface Elevation: — LoggedB : R.J. Bielefeld, CEG
Y
Depth to Groundwater: None Date Excavated: April 26, 2000 Weather. Overcast, warm
DESCRIPTION&CLASSIFICATION
SAMPLE TEST RESULTS AND COMMENTS
DESCRIPTION&REMARKS (inches) SOIL TYPE CONSISTENCY NO.
0.0-12.0: Clay, sandy; dark brown, wet,
roots Cl Stiff
6----
..-42....
12.0-18.0: Sand; reddish brown, wet, Sp Medium
gravel dense
...48----
24.0-72.0: sand, clayey with gravel; Caving
seepage, coarse grained, mottled ••..........
....24....
....30....
Sc Medium
-••36.... dense
....42....
....48....
....54....
...60....
...66....
....72....
Bottom of test pit=72"
Backfilled
----84....
...90....
....96....
..402...
American Engineering TEST PIT LOG
Corporation
SWEETWATER CENTER
PROJECT NO. DATE TEST PIT
4032 148th Avenue NE•Redmond o WA 98052 NO. TP-5
Tel.(425)881-7430•Fax.(425)881-7731 2039 June 22,2000
Excavation Method: Case Backhoe Surface Elevation: — Logged By: R.J. Bielefeld, CEG
Depth to Groundwater: None Date Excavated: April 26, 2000 Weather: Overcast,warm
DESCRIPTION&CLASSIFICATION
SAMPLE TEST RESULTS AND COMMENTS
DESCRIPTION&REMARKS (inches)DEPTH
SOIL TYPE CONSISTENCY NO.
0.0-18.0: Topsoil; Clay with gravel;
dark brown, moist, roots
6.....
CI Soft
....42....
....48....
18.0-24.0: Clay, gravelly; reddish CI Medium stiff
brown, moist
24---
24.0-48.0: Sand, clayey; reddish brown,
oxidized, mottled, wet, roots
....30....
Sc Medium V Seepage
....36..... dense
............
i
....42....
48.0-84.0: Clay; gray brown, wet,
mottled
....54....
CL—CH Stiff Sides of TP caving but no soft gravel at
....60..... bottom
— — — — — — — — — — — — ----66.... - - - -- - - - - - — — — — — — — — — — — —
Sand layer Sp Medium
--.'---.-"' dense
— — — — — — — — — — — — ---- - - - — — — — — — — — — — — — — — — —
Inflow abundant
CL—CH Stiff
:78--•-
....84....
....90....
....96....
...402...
American Engineering TEST PIT LOG
Corporation
SWEETWATER CENTER
0@-" ift PROJECT NO. DATE TEST PIT
4032 148th Avenue NE•Redmond•WA 98052 NO. TP-6
Tel.(425)881-7430 9 Fax.(425)881-7731 2039 June 22,2000
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Project No . : 99-123 Octe: 5-25-1900
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Project No . : 99-123 Date: 5-22--1900
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Appendix B
APPENDIX B
Guide Specifications — Site Earthwork
for
1. GENERAL
A. Scope of Work
These specifications and applicable plans pertain to and include all site earthwork including, but
not limited to, the finishing of all labor, tools, and equipment necessary for site clearing and stripping,
disposal of excess materials, excavation, preparation of foundation materials for receiving fill, and
placement and compaction of fill to the lines and grades shown on the project grading plans.
B. Performance
The Contractor warrants all work to be performed and all materials to be furnished under this
contract against defects in materials or workmanship for a period of o- c year(s) from the days of
written acceptance of the entire construction work by the Owner.
Upon written notice of any defect in materials or workmanship during said O„e year period,the
Contractor shall, at the option of the Owner, repair or replace said defect and any damage to other work
caused by or resulting from such defect without cost to the Owner. This shall not limit any rights of the
Owner under the"acceptance and inspection"clause of this contract.
The Contractor shall be responsible for the satisfactory completion of all site earthwork in
accordance with the project plans and specifications. This work shall be observed and tested by a
representative of American Engineering, hereinafter known as the Engineer. Both the Engineer and the
Architect are the Owner's representatives. If the Contractor should fail to meet the technical or design
requirements embodies in this document and on the applicable plans, he shall make the necessary
readjustments until all work is deemed satisfactory as determined by the Engineer and the
Architect/Engineer. No deviation from the specifications shall be made except upon written approval of the
Geotechnical Engineer or Architect.
No site earthwork shall be performed without the physical presence or approval of the
Geotechnical Engineer. The Contractor shall notify the Geotechnical Engineer at least twenty-four hours
prior to commencement of any aspect of the site earthwork.
The Geotechnical Engineer shall be the Owner's representative to observe the grading operations
during the site preparation work and the placement and compaction of fills. He shall make enough visits to
the site to familiarize himself generally with the progress and quality of the work. He shall make a
sufficient number of tests and/or observations to enable him to form an opinion regarding the adequacy of
the site preparation, the acceptability of the fill material, and the extent to which the compaction of the fill,
as placed, meets the specification requirements. Any fill that does not meet the specification requirements
shall be removed and/or recompacted until the requirements are satisfied.
In accordance with generally accepted construction practices,the Contractor shall be solely and
completely responsible for working conditions at the job site, including safety of all persons and property
during performance of the work. This requirement shall apply continuously and shall not be limited to
normal work hours.
B-1
APPENDIX B
Anv construction review of the Contractor's performance conducted by the Geotechnical Engineer
is not int.-nded to include review of the adequacy of the Contractor's safety measures in,on or near the
construction site.
Upon completion of the construction work, the Contractor shall certify that all compacted fills and
foundations are in place at the correct locations, have the correct dimensions, are plumb,and have been
constructed in accordance with sound construction practice. In addition, he shall cerdfv that the materials
used are of the types, quantity and quality required by the plans and specifications.
C. Site and Foundation Conditions
The Contractor is presumed to have visited the site and to have familiarized himself with existing
site conditions. The Contractor shall not be relieved of liability under the contract for any loss sustained as
a result of any variance between conditions indicated by or deduced from the soil report and the actual
conditions encountered during the course of the work.
The Contractor shall, upon becoming aware of surface and/or subsurface conditions differing from
those disclosed by the original soil investigation, promptly notify the Owner as to the nature and extent of
the differing conditions, first verbally to permit verification of the conditions, and then in writing. No claim
by the Contractor for any conditions differing from those anticipated in the plans and specifications and
disclosed by the soil investigation will be allowed unless the Contractor has so notified the Owner, verbal%
and in«-citing, as required above, of such changed conditions.
D. Dust Control
The Contractor shall assume responsibility for the alleviation or prevention of any dust nuisance on
or about the site or off-site borrow areas. The Contractor shall assume all liability, including court costs of
co-defendant, for all claims related to dust or windblown materials attributable to his work.
IL DEFINITION OF TEXVIS
Structural Fill —All soil or soil-rock material placed at the site in order to raise grades or to backfill
excavations, and upon which the Geotechnical Engineer has been sufficient tests and/or observations to
enable him to issue a written statement that, in his opinion,the fill has been placed and compacted in
accordance with the specification requirements.
On-Site Material—Material obtained from the required site excavations.
Import Material— Material obtained from off-site borrow areas.
ASTyI Specifications —The 1994 edition of the American Society for Testing and Materials Standards.
Degree of Compaction —The ratio, expressed as a percentage, of the in-place dry density of the
compacted fill material to the maximum dry density of the same material as determined by ASTv1 Test
Designation D 1»7-78.
L-\Maria\WPC0CS\EARTHWRV_SPK B-Z
APPENDIX B
M. SITE PREPARATION
A. Clearing and Grubbing
The contractor shall accept the site in its present condition and shall remove the area of the
designated project earthwork all obstructions including and any other matter determined by the
Geotechnical Engineer to be deleterious. Such material shall become the property of the Contractor and
shall be removed from the site. Holes resulting from the removal of underground obstructions that extend
below finish grades shall be cleared and backfilled with structural fill.
B. Stripping
Where vegetation exists,the site shall be stripped to a minimum depth of six to eight inches or to
such greater depth as the Geotechnical Engineer in the field may consider as being ad,,isable to remove all
surface vegetation and organic laden topsoil. Stripped topsoil with an organic content in excess of 3
percent by volume shall be stockpiled for possible use in landscaped areas.
IV. EXCAVATION
All excavations shall be performed to the lines and grades and within the tolerances specified on
the project grading plans. All overexcavation below the grades specified shall be backtilled at the
Contractor's expense and shall be compacted in accordance with the specifications. The Contractor shall
assume full responsibility for the stability of all temporary construction slopes at the site.
V. SUBGRADE PREPARATION
Surfaces to receive compacted fill, and those on which concrete slabs and pavements will be
constructed, shall be scarified to a minimum depth of 6 inches and compacted. All ruts,hummocks, or
other uneven surface features shall be removed by surface grading prior to placement of any fill materials.
All areas which are to receive fill material shall be approved by the Geotechnical Engineer prior to
placement of any fill material.
VI. GENERAL REQUIREMENTS FOR FILL MATERIAL
All fill material must be approved by the Geotechnical Engineer. The material shall be a soil or
soil-rock mixture which is free from organic matter or other deleterious substances. The fill material shall
not contain rocks or rock fragments over 6 inches in greatest dimension and not more than 15 percent shall
be over 2.5 inches in greatest dimension. On-site material having an organic content of less than 3 percent
by volume is suitable for use as fill in all areas except where non-expansive import material is specified.
All imported fill material shall be non-expansive with a plasticity index of 12 or less.
VIE[. PLACING AND COMPACTING FILL MATERIAL
All structural fill shall be compacted by mechanical means to produce a minimum degree of
compaction of 95 percent as determined by ASTM Test Designation D 1557-78. Field density tests shall be
performed in accordance with either ASTM Test Designation D1556-64 (Sand-Cone Method)or ASTM
Test Designation D2922-81 and D3017-78 (Nuclear Probe Method). The locations and number of field
density tests shall be determined by the Geotechnical Engineer. The results of these tests and compliance
with these specifications shall be the basis upon which satisfactory completion of work shall be judged by
the Geotechnical Engineer.
1AMana\WPD0CS\EARTHWRKSPK B-3
APPENDIX B
VU1 TRENCH BACKFILL
Pipeline trenches shall be backfilled with compacted structural fill placed in lifts not exceeding 8
inches of uncompacted thickness. If on-site soils is used,the material shall be compacted by mechanical
means to a minimum degree of compaction of 90 percent. Imported sand may also be used for back Ding
trenches provided it is compacted to at least 95 percent. If imported sand backfilling is used, sufficent
water shall be added during the trench backfilling operations to prevent the soil from bullring during
compaction. In all building pad and pavement areas,the upper 3 feet of trench backfill shall be compacted
to a minimum degree of compaction of 95 percent for on-site soils and imported sand backfill.
IX. TREATMENT AFTER COMPLETION OF EARTHWORK
After the earthwork operations have been completed and the Geotechnical Engineer has finished his
observation of the work, no further earthwork operations shall be performed except with the approval of
and under the observation of the Geotechnical Engineer
It shall be the responsibility of the Contractor to prevent erosion of freshly graded areas during
construction and until such time as permanent drainage and erosion control measures have been installed.
1:'%Wa\WPDOCS\EARTHVAMSPK 8--4
Appendix C
Association of Rockery Contractors
Standard Rockery Construction Guidelines
1.01 INTRODUCTION
1.01.1 Historical Back_r>; ound: These standard rockery construction guidelines have been developed in an
effort to provide a more stringent degree of control on rockery materials and construction methodology in the
Pacific Northwest. They have been assembled from numerous other standards presently in use in the area from
expertise provided by local geotechnical engineers, and from the wide experience of the members of the
Association of Rockery Contractors (ARC).
1.01.2 Goal: The primary goals of this document are to standardize the methods of construction for rockeries
over four feet in height, and to provide a warranty for the materials used in construction and the workmanship
employed in construction. This standard has also been developed in a manner that makes it,to the best of
ARC's knowledge, more stringent than the other standards presently in use by local municipalities.
2.01 MATERIALS
2.01.1 Rock Quality: All rock shall be sound, weathering resistant, angular ledge rock. The longest dimension
of any individual rock should not exceed three times its shortest dimension. Acceptability of rock will be
determined by laboratory tests as hereinafter specified, geologic examination and historical usage records.
All rock delivered to and incorporated in the project shall meet the following minimum specifications:
a. .-absorption Not more than 2.0%for igneous and metamorphic rock tvpes.
Not more than 3.0%for sedimentary rock types.
b. .4ccelerated Expansion(1 S days) Not more than 15%breakdown
(CRD-C-148)"1. '2
C. Soundness Not greater than.i%loss
(MgSO4 at 3 cycles)
(CRD-C-137)
d. Unconfined Compressive Strength Intact strength of 15,000 psi or greater for igneous and
AST11 D-2938-79(reapproved 1979) metamorphic rocks, and 8,000 psi or greater for sedimentary rock.
$I. The test sample will be prepared and tested in accordance with the Corps of Engineers Testing procedure CRD-C--148,
Method of Testing Stone for Expansive Breakdown oil Soaking in Ethylene Glycol." Test requirements of not more than 15
percent breakdown will be computed by dividing lire number of individual pieces of initial sample suffering breakdown that is,
separating into two or more pieces by lire total number of initial pieces in the sample.
"2. Accelerated expansion tests should also include analyses of the fractures and veins found in the rock. Many probiems
associated with rockery failures are related to the rock fractures and veins found within tine rock and not the rock itself.
Page I
Source: Association of Rockery Contractors, P.O. Box 1794,Woodinville,WA 98072 4/4/89
Tel.(425)481-3456 9 Fax.(425)481-7222
Association of Rockery Contractors
Standard Rockery Constriction Guidelines
2.01.2 Frequency of Testing: Quarry sources for rockery rock shall begin a testing program when either
becoming a supplier or when a new area of the source pit is opened. The tests described in Section 2.01.1 shall
be performed for every four thousand(4,000) tons for the first twelve thousand(12,000)tons of material
blasted and removed to established that specific rock source. The tests shall then be performed once a year or
at an apparent change in material. If problems with a specific area in a pit or with a particular material are
encountered, the initial testing cycle shall be restarted.
2.01.3 Rock Density: Recognizing that numerous sources of rock exists, and that the nature of rock will vary
not only between sources but also within each source, the density of the rock shall be greater than one hundred
fifty-five (155) pcf. Typically, rocks used for rockery construction shall be sized approximately as follows:
Rock Size Rock Weight
Small to large 50-200 pounds
one man
Small to large 200-700 pounds
two man
Small to large 700-2000 pounds
three man
Small to large 2000-4000 pounds
four man
Five man 4000-6000 pounds
Six man 6000-8000 pounds
Two and one-man rock and sometimes smaller are often used to fill surface gaps along the top of the
completed rockery to create an aesthetically pleasing surface. This is an acceptable practice provided none of
the events described in Section 3.01.5 occur and that the owner prevents people from climbing or walking on
the completed rockery.
In rockeries over eight feet in height, it should not be possible to move the large—sized rocks (four to six—man
size) with a prybar. If these rocks can be moved, the rockery should not be considered capable of restraining
any significant lateral load. However, it is both practical and even desirable that smaller rocks, particularly
those used for "chinking" purposes can be moved with a prybar to achieve the "best fit".
2.01.4 Submittals: The rock source shall present current geologic and test data for the testing for the minimum
guidelines described in Section 2.01.1 on request by either the rockery contractor, the client, or the applicable
municipality.
Page 2
Source: Association of Rockery Contractors,P.O. Box 1794,Woodinville,WA 98072 4/4/89
Tel.(425)481-3456 • Fax.(425)481-7222
Association of Rockery Contractors
Standard Rockery Constn-iction Guidelines
3.01 ROCKERY CONSTRUCTION
3.01.1 General: Rockery construction is a craft and depends largely on the skill and experience of the builder.
A rockery is a protective system which helps to retard the weathering and erosion process on an exposed cut or
fill soil face. While by its nature (the mass, size and shape of the rocks), it will provide some degree of
retention. It is not a designed or engineered system in the sense a reinforced concrete retaining wall would be
considered designed or engineered. The degree of retention achieved is dependent on the size of rock used,
that is, the mass or weight and the height of the rockery being constructed. The larger the rock, the more
competent the rockery. To accomplish this, all rockeries in excess of four feet in height should be built on a
"mass" basis. To provide a competent and adequate rockery structure, all rockeries constructed in front of
either cuts or fills in excess of eight feet in height should be bid and constructed in accordance with these
standard guidelines and the geotechnical engineers supplemental recommendations. Both the standard
guidelines and the supplemental geotechnical recommendations should be provided to prospective bidders
before bidding and the start of construction.
The same geotechnical engineer should be retained to monitor rockery construction and to verify, in writing,
that the rockery was constructed in general accordance with this ARC standard and with this supplemental
recommendations, in a professional manner and of competent and suitable materials.
3.01.2 Geotechnical En_ineer: The geotechnical engineer retained to provide necessary supplemental rockery
construction guidelines shall be a practicing geotechnical/civil engineer licensed as a professional civil engineer
in the State of Washington who has at least four years of professional employment as a geotechnical engineer in
responsible charge, including experience with fill construction and stability and rockery construction. The
geotechnical engineer should be hired either by the rockery contractor or the client.
3.01.3 Responsibility: The ultimate responsibility for rockery construction should remain with the rockery
builder. However, rockeries protecting moderate to thick fills, with steep sloping surfaces above or below
them, with multiple steps, with foundation or other loads affecting them, protecting sandy or gravelly soils
subject to raveling with seepage or wet conditions, or that are more than eight feet in height, all represent
special conditions and require consultation and/or advice from qualified experts.
3.01.4 Workmanship: All workmanship is guaranteed by the rockery contractor and all materials are
guaranteed by supplying quarry for a period of six years from the date of completion of erection, providing no
modification or changes to the conditions existing at the time of completion are made.
3.01.5 Changes to Finished Product: Such changes include, but are not necessarily limited to excavation of
ditches or trenches within a distance of less than 1.5 times the rockery height measured from the toe of the
rockery, removal of any material from the subgrade in front of the rockery, excavation and/or removal of
material from any location behind the rockery within a distance at least equal to the rockery's height, the
addition of any surcharge or other loads within a similar distance of the top of the rockery,or surface or
subsurface water forced, directed, or otherwise caused to flow behind the rockery in any quantity.
Page 3
Source: Association of Rockery Contractors. P.O. Box 1794,Woodinville,WA 98072 4/4/89
Tel.(425)481-3456 9 Fax.(425)481-7222
Association of Rockery Contractors
Standard Rockery Constn_ction Guidelines
3.01.6 Slopes: Slopes above rockeries should be kept as flat as possible, but should not exceed 2:1
(Horizontal:Vertical) unless the rockery is designed specifically to provide some restraint to the load imposed by
the slope. Any slope existing above a completed rockery should be provided with a vegetative cover by the owner
to help reduce the potential for surface water flow induced erosion. It should consist of a deep rooted, rapid growth
vegetative mat and typically will be placed by hydroseeding and covered with a mulch. It is often useful to overlay
the seed and mulch with either pegged in-place jute matting, or some other form of approved geotechnical fabric
to maintain the seed in-place until the root mat has an opportunity to germinate and take hold.
3.01.7 Monitoring: All rockeries constructed against cuts or fills in excess of eight feet in height shall be
periodically monitored during construction by the geotechnical engineer to verify the nature and quality of the
materials being used are appropriate, that the construction procedures are appropriate, and that the rockery is
being constructed in a generally professional manner and in accordance with this ARC standards and any
supplemental recommendations.
On completion of the rockery, the geotechnical engineer shall submit to the client, the rockery contractor, and
to the appropriate municipality, copies of his rockery examination reports along with a final report summarizing
rockery construction.
3.01.8 Fill Compaction: Where rockeries are constructed in front of a fill, it is imperative that the owner ensure
the fill be placed and compacted in a manner that will provide a competent fill mass. To achieve this goal, all fills
should consist of relatively clean,organic and debris—free granular materials with a maximum size of four inches.
Ideally, but particularly if placement and compaction is to take place during the wet season, they should contain
no more than five percent fines (silt and clay size particles passing the number 200 mesh sieve).
All fills should be placed in thin lifts not exceeding eight inches in loose thickness. Each lift should be
compacted to at least 95 percent of the maximum dry density, as determined by ASTM Test Method D-1557-
78 (Modified Proctor) before any additional fill is placed and compacted. In-place density areas tests should be
performed at random locations within each lift of the fill to verify this degree of compaction is being achieved.
3.01.9 Fill Construction and Reinforcement: There are two methods of constructing a fill against which to
build a rockery. The first, which typically applies to rockeries of less than eight feet in height, is to overbuild
and then cut back the fill. The second, which applies to all rockeries in excess of eight feet in height, is to
construct the fill using a geogrid or geotechnical fabric reinforcement.
Overbuilding the fill allows for satisfactory compaction of the fill mass out beyond the location of the fill face to
be protected. Overbuilding also allows the earthwork contractor to use larger and more effective compaction
equipment in his compactive efforts, thereby typically achieving a more competent fill mass. Cutting back into
the well compacted fill also typically results in construction of a competent near vertical fill face against which
to build the rockery.
For the higher rockeries, the use of a geogrid or geotechnical fabric to help reinforce the fill results in
construction of a more stable fill face against which to construct the rockery. This form of construction leads to
a longer lasting and more stable rockery and helps reduce the risk of significant long term maintenance.
Page 4
Source: Association of Rockery Contractors. P.O. Box 1794,Woodinville.WA 98072 4/4/89
Tel.(425)481-3456 • Fax.(425)481-7222
Association of Rockery Contractors
Standard Rookery Cortstnxtion Guidelines
This latter form of construction requires a design by the geotechnical engineer for each specific case. The
vertical spacing of the reinforcement, the specific type of reinforcement, and the distance to which it must
extend back into the fill and the amount of lapping must be determined on a rockery-by-rockery basis.
3.01.10 Rockery Kevwav: The first step in rockery construction after general site clearing and/or general
excavation, is to construct a keyway in which to build the rockery. The keyway shall comprise a shallow trench
of between 12 and 18 inches in depth, extending for the full length of the rockery, and inclined back slightly
towards the face being protected. It is typically dug as wide as the rockery (including the width of the rock
filter layer).
If the condition of the protected face is of concern, the keyway should be constructed in sections of manageable
length, that is of a length that can be constructed in one shift or one day's work.
The competency of the keyway subgrade to support the rockery shall be verified by probing with a small
diameter steel rod. The rod shall have a diameter of between 3/s" and !/?, and shall be pushed into the
subgrade in a smooth unaided manner under the body weight of the prober only.
Penetration of up to six inches with some difficulty, shall indicate a"competent" keyway subgrade unless other
factors in the geotechnical engineer's opinion shall indicate otherwise. Penetration in excess of six inches or of
that depth with ease, shall indicate a"soft" subgrade and one that could require treatment. Soft areas of the
subgrade can be "firmed up" by tamping a layer of coarse quarry spalls into the subgrade.
3.01.11 Kevwav and Rockery Drainage: On completion of keyway excavation, a shallow ditch or trench
approximate 12 inches wide and deep, should be dug along the rear edge of the keyway. A minimum four-inch
diameter perforated or slotted ADS drain pipe, or equivalent approved by an engineer, should be placed in this
shallow trench and should be bedded on and surrounded by a free-draining crushed rock. Burial of the drain
pipe in this shallow trench provides protection to the pipe and helps prevent it from being inadvertently crushed
by pieces of the rockery rock. This drain pipe should be installed with sufficient gradient to initiate flow and
should be connected to a positive and permanent discharge.
Positive and permanent drainage should be considered to mean an existing or to be installed storm drain
system, a swale, ditch or other form of surface water flow collection system, a detention or retention pond, or
other stable native site feature or previously installed collection system.
3.01.12 Rockery Thickness: The individual rockery thickness including the rock filter layer should be at least
40 percent of the rockery height. Unless otherwise specified in writing by the rockery "designer", the
individual rocks should be arranged in a single course which when measured to include the filter layer, is equal
to the required rockery thickness.
Page 5
Source: Association of Rockery Contractors, P.O. Box 1794,Woodinville,WA 98072 4/4/89
Tel.(425)481-3456 • Fax. (425)481-7222
Assodation of Rockery Contractors
Standard Rockery Constnxtion Guidelines
3.01.13 Rock Selection: The contractor should have sufficient space available so that he can select from
among a number of stockpiled rocks for each space in the rockery to be filled. Rocks which have shapes which
do not match the spaces offered by the previous course of rock should be placed elsewhere to obtain a better
fit. Rock should be of a generally cubical, tabular or semi-rectangular shape. Any rocks of basically rounded
or tetrahedral form should be rejected or used for filling large void spaces.
Smaller rocks (one to two-man size, or smaller) are often used to create an aesthetically pleasing "top edge"to
a rockery. This is acceptable provided none of the events described in Section 3.01.5 occur, and that people
are prevented from climbing or walking on the finished rockery. This is the owner's responsibility.
3.01.14 Rock Placement: The first course of rock should be placed on firm unyielding soil. There should be
full contact between the rock and soil which may require shaping of the ground surface or slamming or
dropping the rocks into place so that the soil foundation conforms to the rock face bearing on it. As an
alternative, it is satisfactory to place and tamp crushed rock into the subgrade to tighten it up. The bottom of
the first course of rock should be a minimum of 12 inches below the lowest adjacent site grade.
As the rockery is constructed, the rocks should be placed so that there are no continuous joint planes in either
the vertical or lateral direction. Each rock should bear on at least two rocks below it. Rocks should be placed
so that there is some bearing between flat rock faces rather than on joints. Joints between courses should slope
downward towards the material being protected (away from the face of the rockery).
3.01.15 Face Inclination: the face of the rockery should be inclined at a gradient of about 1:6 (H:V) back
towards the face being protected. The inclination should not be constructed flatter than 1H:4V.
3.01.16 Voids: Because of the nature of the product used to construct a rockery, it is virtually impossible to
avoid creating void spaces between individual rocks. However, it should be recognized that voids do not
necessarily constitute a problem in rockery construction.
Where voids of greater than six inches in dimension exist in the face of a rockery, they should be visually
examined to determine if contact between the rocks exist within the thickness of the rockery. If contact does
exit, no further action is required. However, if there is no rock contact within the rockery thickness the void
should be "chinked" with a smaller piece of rock. If a void of greater than six inches exists in the rear face of
the rockery, it should be "chinked" with a smaller rock.
3.01.17 Filter Laver: In order to provide some degree of drainage control behind the rockery and as a means
of helping to prevent loss of soil through the face of the rockery, a drainage filter shall be installed layer
between the rear face of the rockery and the soil face being protected. This filter layer should be at least
12 inches thick and for rockeries in excess of eight feet in height, it should be at least 18 inches thick. It should
be composed of four-inch minus crushed rock or other material approved by the geotechnical engineer.
If one of the rockery rocks extends back to the exposed soil face, it is not necessary that the filter rock layer
extend between it and the soil face.
Page 6
Source: Association of Rockery Contractors, P.O. Box 1794,Woodinville.WA 98072 4/4/89
Tel.(425)481-3456 • Fax.(425)481-7222
Association of Rockery Contractors
Standard Rockery Constnxtion Guidelines
In the event seepage is encountered emanating from a protected face, we recommend the use of a well-graded
filter layer. We do not recommend the use of a geotechnical fabric for other than coverage of relatively small
and isolated seepage areas because it has been the industry's experience that the filter fabric tends to clog
rapidly. This quickly leads to a buildup of hydrostatic pressure which can subsequently cause failure and
collapse of the rockery and is to be avoided.
This clogging is apparently due to the virtual impossibility of achieving fill contact between the soil face, fabric and
rock filter material. If full surface contact cannot be achieved, there is often a tendency for the soil materials to
flush from the protected face into the "pockets" in the fabric which leads to the aforementioned clogging.
3.01.18 Surface Drainaee: It is the owner's responsibility to intercept surface drainage from above the rockery
and direct it away from the rockery to a positive and permanent discharge well below and beyond the toe of the
rockery. Use of other drainage control measures should be determined on a case-by-case basis by the
geotechnical engineer prior to bidding on the project.
Page 7
Source: Associagon of Rockery Contractors, P.O. Box 1794,Woodinville,WA 98072 4/4/89
Tel.(425)481-3456 • Fax.(425)481-7222
b 4
t Z2
T
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Crushed rock filter material ranging between 4 and % inches in size and free of organics, with
less than 5%fines(silt and clay size particles passing the NQ 200 mesh sieve).
Compacted structural fill consisting of free-draining; organic-free material with a maximum size
of 4 inches. Should contain no more than 5%fines(described above).compacted to at least 95%
of ASTM D-1557-78 maximum density.
Tensar SS-1 geogrid, Miraf. or equivalent reinforcement approved by geotechnical engineer.
Perforated or slotted drain pipe with 4-inch minimum diameter bedded on and surrounded by
crushed rock filter material. described above.
Designates size of rock required. i.e. 4-man.
NOTES:
• All fill should be placed in thin lifts not exceeding 6 inches in loose thickness. Each laver should be
compacted to no less than 95%of maximum dry density, as determined by ASTM D-1557-78
(Modified Proctor).
• With exception of upper laver,geofabric reinforcement should be wrapped around exposed fill face and
lapped back beneath overlying fill layer a distance of at least 2 feet.
• Thickness of crushed filter rock laver, B, should be no less than 18 inches.
• Depth of burial of basal layer of rock, D, should be no less than 18 inches.
• Length of reinforcing geofabric, L, shall be feet.
• Geofabric reinforcement layer spacing, Z, and Z,_, shall be and feet, respectively.
• Height of rockery, H. should not exceed feet.
American Engineering TYPICAL DETAIL
Corporation
FILL CONSTRUCTION
ROCKERY LESS THAN 8 FEET IN HEIGHT
4032 148`"Avenue NE•Redmond•WA 98052
Tel:(425)881-7430•Fax.(425)881-7731 Project N2 Date Figure
Email:eg-aec@msn.com
Nfl
i
l
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i
T
F-E3 — L R
LO
Crushed rock filter material ranging between 4 and''/I inches in size and free of organics. with
less than 5%fines(silt and clay size particles passing the N°200 mesh sieve).
Compacted structural fill consisting of free-draining;organic-free material with a maximum size
of 4 inches. Should contain no more than 5%fines(described above).compacted to at least 95%
of ASTM D-1557-78 maximum density.
Tensar SS-1 geogrid, Mirafi. or equivalent reinforcement approved by geotechnical engineer.
Perforated or slotted drain pipe with 4-inch minimum diameter bedded on and surrounded by
crushed rock filter material. described above.
Designates size of rock required. i.e. 4-man.
NOTES:
• All fill should be placed in thin lifts not exceeding 6 inches in loose thickness. Each layer should be
compacted to no less than 95%of maximum drn density, as determined by ASTM D-1557-78
(Modified Proctor).
• With exception of upper layer,geofabric reinforcement should be wrapped around exposed fill face and
lapped back beneath overlying fill layer a distance of at least 2 feet.
• Thickness of crushed filter rock laver, B, should be no less than 18 inches.
• Depth of burial of basal layer of rock, D, should be no less than 18 inches.
• Length of reinforcing geofabric, L, shall be feet.
• Geofabric reinforcement layer spacing, Z, and Z,, shall be and feet, respectively.
• Height of rockery, H. should not exceed feet.
American Engineering TYPICAL DETAIL
Corporadon
FILL CONSTRUCTION
ROCKERY LESS THAN 18 FEET IN HEIGHT
4032 148`"Avenue NE•Redmond•WA 98052
Tel.(425)881-7430• Fax.(425)881-7731 Project N2 Date Figure
Email:eg-aec@msn.com
N4
THIS PARCEL
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