HomeMy WebLinkAboutSWP272711 (9)RECEIVED
JAN 16 2007
CITY OF RENTpH
1t1 LrrY 31'87��
REVISED FINAL GEOTECHNICAL REPORT
Renton Village Storm System Improvement Proj.
City of Renton, Washington
HWA Project No. 2006-067-21
Prepared for
Gray & Osborne, Inc. (G&O #05731.00)
January 12, 2007
HWAGEOSCIENCES INC.
. Geotechnical 1-tigineering
- Hydrogeology
- Geoenvirotunental Services
. Inspection & luting
U HWA GEOSCIENCES INC.
Geoteehnical & Pavement Entim-crint 'Ii•stirr�
January 12, 2007
HWA Project No. 2006-067-21
G&O Project No. 05 73 1. 00
' Gray & Osborne, Inc.
701 Dexter Avenue N Ste 200
Seattle, Washington 98109-1004
Attention: Mr. Barry Baker, P.E.
Subject: REVISED FINAL GEOTECHNICAL REPORT
Renton Village Storm System Improvement Project
City of Renton, Washington
Dear Mr. Baker:
As requested, HWA GeoSciences Inc. completed a design level geotechnical engineering
study for the Renton Village Storm System Improvement Project. Results of our
investigation and geotechnical recommendations for design and construction of the
replacement culvert were provided in a draft report dated August 16, 2006. Revisions were
made to that report based on comments from the City and project team discussions, and a
final report was submitted November 9, 2006. However, additional subsurface
explorations and analyses were subsequently conducted at your request to determine if
subsurface conditions were more favorable along potential alternate alignments further to
the east. This revised final report includes the findings of the additional investigation and
analyses performed.
We appreciate the opportunity to have provided geotechnical services on this project.
Sincerely,
HWA GEO NCES INC.
Lorne Balanko, P.E. 19730 - 64th Avenue W.
Geotechnical Engineer/President suite 200
Lynnwood, WA 98036.5957
' Tel: 425.774.0106
Fax: 425.774.2714
www.hwageosciences.com
TABLE OF CONTENTS
Page
1.0 INTRODUCTION............................................................................................................1
1.1
GENERAL.....................................................................................................1
1.2
PROJECT DESCRIPTION................................................................................1
1.3
SCOPE OF SERVICES AND AUTHORIZATION
..................................................2
2.0 FIELD AND LABORATORY INVESTIGATIONS................................................................2
2.1
FIELD INVESTIGATION.................................................................................2
2.2
LABORATORY TESTING................................................................................3
3.0 GEOLOGIC AND SUBSURFACE CONDITIONS.................................................................3
3.1
SURFACE CONDITIONS.................................................................................3
3.2
GENERAL GEOLOGY....................................................................................4
3.3
SUBSURFACE CONDITIONS...........................................................................4
3.4
GROUND WATER CONDITIONS....................................................................5
4.0 CONCLUSIONS AND RECOMMENDATIONS..................................................................6
4.1
GENERAL.....................................................................................................6
4.2
FOUNDATIONS.............................................................................................7
4.2.1 Seismic Considerations.................................................................7
4.2.2 Subgrade Conditions.....................................................................8
4.2.3 Estimated Settlement.....................................................................9
4.3
LATERAL EARTH PRESSURES.......................................................................12
4.4
EXCAVATION STABILITY AND SHORING.......................................................13
4.4.1 General..........................................................................................13
4.4.2 Shoring..........................................................................................13
4.5
DEWATERING..............................................................................................14
4.6
BACKFILL PLACEMENT AND COMPACTION
..................................................15
4.7
EROSION CONSIDERATIONS.........................................................................16
5.0 CONDITIONS AND LIMITATIONS..................................................................................16
LIST OF FIGURES
Figure 1. Vicinity Map
Figure 2. Site and Exploration Plan
Figure 3. Cross Section A -A'
Figure 4. Trench Subgrade Preparation
2006-067 Rev Final2.doc i HWA GEOSCEENCES INC.
APPENDICES
Appendix A: Explorations
Figure A-1
Legend of Terms and Symbols Used on Exploration Logs
Figures A-2 to A-8
Logs of Boreholes BH-1 through BH-7
Appendix B: Laboratory Test Results
Figure B-1
Liquid Limit, Plastic Limit and Plasticity Index of Soils
Figures B-2 to B-5
Grain Size Distribution Test Results
Figure B-6
One -Dimensional Consolidation Plot
Appendix C: Aquifer Testing and Analysis
2006-067 Rev Finalldoc 11 HWA GEoSCMNCES INC.
REVISED FINAL GEOTECHNICAL REPORT
RENTON VILLAGE STORM SYSTEM IMPROVEMENT PROJECT
RENTON, WASHINGTON
' 1.0 INTRODUCTION
1.1 GENERAL
This report presents the results of a geotechnical engineering study completed by HWA
GeoSciences Inc. (HWA) for the planned replacement of the Renton Village storm sewer
system, located between South Grady Way and I-405, in the City of Renton, Washington.
The project location is indicated on Figure 1. The objective of our work was to investigate
subsurface soil and ground water conditions, and provide geotechnical recommendations for
design and construction of the replacement storm sewer system.
a 1.2 PROJECT DESCRIPTION
' The project will replace two sections of existing pipe; a 440-foot long 42-inch concrete pipe,
followed by a 220-foot long 48-inch corrugated metal pipe (CMP) culvert. The 42-inch pipe
drains from an existing 72-inch pipe within the driveway just southeast of the Thriftway store
in the Renton Village complex. The existing CMP discharges stormwater to a small stream
(Rolling Hills Creek) at the south side of the One Renton Place (office building) parking lot,
immediately north of I-405. The existing and proposed storm sewer alignments, together
with exploration locations, are shown on the Site and Exploration Plan, Figure 2. Presently,
the invert elevations of the existing lines at inlet and outlet ends are understood to be of the
order of 21 and 19 feet, respectively.
Corrosion of the existing CMP at the outfall and collapse of the end of the pipe destroyed two
parking spaces and left a portion of the existing culvert exposed, about two years ago. At the
catch basin in the parking lot, which is the juncture of the concrete and CMP sections, we
understand that the invert elevation of the 48-inch CMP is about 17.61 feet, while the invert
' elevation at the outfall is about 19.39 feet, giving the CMP a negative slope. The difference
in elevations suggests that the catch basin has settled at least 1.78 feet.
Based on information provided to date, we understand the City plans to remove the existing
storm sewer and replace it with a larger culvert. The preferred and alternate alignments as
determined before the geotechnical exploration are shown on Figure 2. Based on the
' exploration data provided in the draft and final reports, a second alternative alignment close
to the One Renton Place building was considered. To evaluate subsurface conditions along
' the second alternative alignment, three additional borings were advanced in December 2006.
January 12, 2007
HWA Project No. 2006-067-21
Based on the subsurface conditions encountered in the additional borings, we understand the
original alignment remains the preferred.
The preferred pipeline, as proposed by Gray & Osborne, Inc. (G&O), is a 4-sided,
prefabricated concrete, box culvert, with dimensions of either 4 by 6 or 4 by 8 feet. It will
consist of either an integral box section, or an inverted U-section set on a prefabricated
' concrete base. Alternatively, the existing culvert may be replaced with twin 48-inch diameter
concrete pipes.
Although design details of the new culvert are still in progress, we understand that the invert
elevation will be of the order of 6 to 8 feet below existing grades. Based on existing ground
elevations, this would provide for culvert invert elevations of approximately 21 feet at the
upstream end, decreasing to approximately 19 feet at the outfall end. After culvert
replacement, the asphaltic concrete pavement grades will be restored to approximately the
existing ones. A new outfall area will be constructed and the lost parking spots restored.
1.3 SCOPE OF SERVICES AND AUTHORIZATION
Our work was conducted in accordance with our Project Cost Estimate, submitted to
Mr. Barry Baker, of G&O, on October 17, 2005. Verbal authorization to proceed was given
by Mr. Barry Baker on May 15, 2006. Our initial scope of work included performing four
exploratory boreholes at the site, installing two piezometer wells, slug testing and
hydrogeological analysis, laboratory testing, geotechnical engineering analyses, and providing
geotechnical recommendations for the proposed replacement culvert. Additional work was
authorized on December 5, 2006, per our scope and cost estimate of the same date, and
included drilling three additional boreholes along an alternative alignment, consolidation
testing of a peat sample and settlement analyses, and revision of the previously submitted
fmal report.
2.0 FIELD AND LABORATORY INVESTIGATIONS
2.1 FIELD INVESTIGATION
' We drilled four test boreholes along the proposed alignment on June 2nd and 13t1i, 2006.
Three additional boreholes were drilled on December 8, 2006. The boreholes were
designated BH-1 through 131-1-7, whose approximate locations are shown on the Site and
Exploration Plan, Figure 2. Borehole BH-2A was attempted beyond the east side of a high -
voltage transmission line, but was terminated at 6.5 feet due to a hard obstruction (later
determined to be an unmarked utility vault that was never used).
To monitor ground water conditions, we installed slotted standpipe piezometers in boreholes
BH-1 and 131-1-4. Ground water readings were taken on June 16, 2006, and again on June 23,
2006-067 Rev Finalldoc 2 HWA GEOSCIENCES INC.
1 January 12, 2007
HWA Project No. 2006-067-21
2006, to determine stabilized water table conditions. Slug testing in the piezometers was also
performed on June 23, 2006. Field exploration methods are described in more detail, and
summary borehole logs and ground water results are presented in Appendix A.
' 2.2 LABORATORY TESTING
Laboratory tests were conducted on selected samples obtained from the boreholes to
characterize relevant engineering properties of the site soils. Laboratory tests initially
included determination of in -situ moisture content, particle size analyses, Atterberg Limits,
rand organic content of subsurface soil deposits where appropriate. During the second phase
of investigation, an undisturbed sample of the peat deposit was obtained to permit
consolidation testing for purposes of refining settlement estimates related to construction of
the new stormwater conveyance system. The tests were conducted in general accordance
with appropriate American Society of Testing and Materials (ASTM) Standards, and are
discussed in further detail in Appendix B. The results are presented in Appendix B, or are
displayed on the exploratory logs in Appendix A.
3.0 GEOLOGIC AND SUBSURFACE CONDITIONS
3.1 SURFACE CONDITIONS
The ground surface along the storm sewer alignment is relatively flat, sloping gently to the
' south at elevations ranging from approximately 26 to 30 feet. The ground surface along the
alignment consists of paved parking lots on both sides of South Renton Village Place. The
existing parking lot pavements are in good condition, aside from settlements experienced at
Ithe south end of the site, and settlement in the vicinity of the existing catch basin
approximately 225 feet north of the south edge of the parking lot. Also, most of the parking
lot south of Renton Village Place appears broadly down -warped, with scattered long
pavement cracks existing in areas within which the boreholes encountered peat. Pavement
damage at the south edge of the parking lot includes the erosion and loss of two parking
' spaces and the exposure of part of the existing CMP storm sewer culvert. In addition to the
storm sewer, there are significant underground utilities in the project area, including sanitary
sewer lines, water mains, telephone and natural gas.
Water from the current storm sewer system is discharged into a drainage ditch/stream on the
south end of the site. The amount of water discharged is variable and depends on local
' precipitation conditions. During a heavy rain storm, the water discharging from the storm
sewer system was observed as high as a few inches from the top of the exposed culvert.
2006-067 Rev Final2.doc 3 HWA GEOSCIENCES INC.
January 12, 2007
HWA Project No. 2006-067-21
3.2 GENERAL GEOLOGY
Geologic information for the site was obtained from the Geologic Map of the Renton
Quadrangle, King County, Washington (Mullineaux, D. R., 1965). This map indicates that
there are three surficial geologic units crossed by the storm system. From north to south,
these consist of the following:
' 1) Quaternary recessional glaciolacustrine deposits, consisting primarily of loose to
medium dense sand with some silt and clay. This material was deposited in an ice -
dammed lake in the Duwamish Valley, during recession of the latest continental
glaciation; the Vashon Stade of the Fraser Glaciation.
I
2) Holocene alluvium from the Cedar River, consisting of loose sand and gravel with
thin beds of silt, clay, and peat.
3) The Eocene Renton Formation, consisting of sandstone, mudstone, and shale and
some coal beds. The sandstone is arkosic (25% or more feldspar) and irregularly
cemented with calcium carbonate. Typically, it is poorly indurated and can be drilled
with a hollow stem auger. The hill slope immediately south of I-405 is also mapped
as the Renton Formation.
3.3 SUBSURFACE CONDITIONS
Native soils encountered in the boreholes were in general conformance with the geologic
map. However, from 1 to 3 feet of fill was present, beneath the asphalt pavement, in each of
the borings, overlying native soils. The soils encountered were as follows, in order from
youngest to oldest:
Fill: Gravel sub -base material was present beneath the parking lot pavement, to depths of
approximately 2 to 3 feet. In 131-1-1, beyond the southern margin of the parking lot, silty sand
fill was present to a depth of one foot.
Buried Topsoil: A one -foot thickness of topsoil was present in BH-1, at a depth interval of
1 to 2 feet, and consisted of dark brown silty clay.
1 Alluvium: Soft peat, organic silt, and loose to medium dense silty sand. deposited in a
fluvial environment, were encountered in borehole 131-1-2. The total thickness of peat and
organic silt in BH-2 was approximately 15'/2 feet, extending from 8'/2 to 20 feet and 24 to 28
feet below the ground surface. Supplemental drilling was conducted along an alternative
alignment to determine if it was possible to avoid the peat. However, the additional drilling
encountered a 10 foot thickness of peat and organic silt at 131-1-5, nearly 6 feet of peat in BH-
6, and nearly 5 feet of peat in 131-1-7. The alluvium, as described above, extended to the full
depths explored (26.5 to 31.5 feet) in these additional three boreholes. Both the peat and
2006-067 Rev Final2.doc 4 HWA GEOSCIENCES INC.
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HWA Project No. 2006-067-21
organic silt are highly compressible, which likely contributed to the settlement of the catch
basin and storm pipe by borehole BH-2, and the segment of the north -south sanitary sewer
line crossing this area. Boreholes BH-3 and BH-4 encountered silty sand alluvium to depths
of 7 and 4'/z feet, respectively.
Recessional Glaciolacustrine: This deposit was encountered in boreholes BH-1 through
BH-4, and was revealed to be a generally fining -upward sequence, typical of a glacial
meltwater depositional environment in which the meltwater source is receding. It consisted
of several feet of medium stiff clay, over stiff silt and medium dense silty sand.
Sandstone (Renton Formation): Borehole BH-1 encountered medium dense to very dense
weathered sandstone, at a depth of 10'/2 feet. The feldspar and rock grains crumbled under
finger pressure, as well as during grain size analyses, indicating a high degree of chemical
weathering. This does not occur with similar -appearing glacial advance outwash sands in the
area. Boreholes BH-2 through BH-4 were terminated at greater depths than BH-1, without
encountering the Renton Formation.
3.4 GROUND WATER CONDITIONS
Ground water levels observed in the boreholes were recorded on the borehole logs. However,
observations of water levels during drilling can be misleading. Actual ground water levels
are often higher than those observed, because boreholes are typically open only for a short
time, and the auger used to advance the borehole can smear the side of the hole inhibiting
seepage. Moreover, the ground water elevations reported on the borehole logs are for the
specific dates and locations indicated and, therefore, may not be indicative of other times
and/or locations.
Ground water level readings were taken in the open borings upon completion and in the
piezometers on June 16 and 23, 2006. Water level observations in the open borings and
piezometers are summarized in Table 1. However, to gain an appreciation of seasonal
ground water variations, measurements should be made during times of typical seasonal high
ground water, in late winter and early spring.
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' January 12, 2007
HWA Project No. 2006-067-21
Table 1: Ground Water Measurements for Boreholes BH-1 through BH-7
Borehole
Designation
Surface
Elevation
(ft)
Open Borehole
Water Depth (ft)
Piezometer Water Depth (ft)
June 16, 2006
June 23, 2006
BH-1
26
7.5
5.60
5.60
BH-2
27
2.5
NA
NA
BH-3
29
12.5
NA
NA
BH-4
30
10.5
6.70
6.79
BH-5
28
NA
NA
NA
BH-6
29
8.0
NA
NA
BH-7
29
5.0
NA
NA
1 Soil and ground water conditions are depicted schematically on Figure 3, which represents a
cross-section along the approximate preferred alignment of the proposed new culvert
improvements.
Aquifer testing was performed by HWA on June 23, 2006, and consisted of slug testing and
' pump testing. The methods are discussed in Appendix C, and conclusions are summarized in
Section 4.5, Dewatering.
' 4.0 CONCLUSIONS AND RECOMMENDATIONS
' 4.1 GENERAL
Based on the subsurface conditions encountered in our geotechnical investigation, the
following will affect the design and construction of the proposed project:
• The proposed storm sewer will traverse loose or soft alluvial soils below the ground water
' table. In general, the soils are capable of supporting the new sewer, considering that the
culvert sections will likely weigh less than the soil it displaces. However, over-
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' January 12, 2007
HWA Project No. 2006-067-21
t
excavation of trench base through the peat area will be necessary to effect suitable
subgrade support conditions and, depending upon the width and configuration of the
trench excavation actually undertaken for the line by the contractor, it is possible that the
' weight of combined backfill and culvert could increase stresses on the underlying
compressible soils. Therefore, we recommend the use of a foamed concrete CDF as the
culvert foundation, and lightweight fill such as bottom ash for trench backfill up to 2 feet
' from the ground surface. Additionally, depending on trench characteristics, it may be
desirable to backfill some of the culvert with the same material to reduce stresses to at
' least a neutral condition.
• An existing 12-inch A.C. sewer pipeline is in close proximity to the proposed alignments,
' lying some 40 feet east of the existing 48-inch CMP and of the order of 20 feet east of the
preferred replacement alignment, as indicated on Figure 2. This sewer line was camera
surveyed by the City on October 23, 2006, and the results indicate a sag in the line,
' extending from approximately its under -crossing of the existing 42-inch concrete storm
line to a point about 160 feet to the south. This sag is considered to represent post -
installation settlement, likely due to consolidation of underlying compressible soils. We
' understand that the City considers the settled sewer pipeline to be presently serviceable,
but is presumably sensitive to additional settlement and vibration.
' • Ground water levels should be anticipated to range from approximately 3 to 7 feet above
trench invert. Much of the dewatering requirements for this project are anticipated to be
' accomplished with sumps. The use of localized sumps would minimize potentially
damaging settlements to adjacent utilities and pavements that can occur with dewatering
wells in such soil conditions.
• Shoring will be needed along most or all the storm sewer trench alignment, depending on
soil type, ground water seepage conditions, and proximity to existing utilities.
■ The following sections provide recommendations for foundation design, shoring and lateral
earth pressures, dewatering, and construction considerations.
4.2 FOUNDATIONS
' 4.2.1 Seismic Considerations
Buried culverts are typically not required to be designed to seismic design standards
' (AASHTO, 1996). Accordingly, unless otherwise requested, seismic parameters have not
been provided herein.
Our assessment of the liquefaction potential of soil deposits at this site suggests that
substantial portions of the silty sand (SP/SM) material encountered in the borings can liquefy
under a moderate to severe earthquake event. Only the silt (ML) and clay (CL/CH), and
2006-067 Rev Finalldoc 7 HWA GEOSCIENCES INC.
January 12, 2007
HWA Project No. 2006-067-21
organic (OH/PT) layers are considered unlikely to liquefy during a design (i.e. 1 in 475 year)
seismic event, because of either their very high fines content and/or inherent plasticity
characteristics.
We understand that the new culvert will have an invert level on the order of 6 to 8 feet in
depth below existing site grades. Hence, allowing for over -excavation needed to construct
the foundation system, the trench base will be 1 to 2 feet lower. Since this depth of
over -excavation could result in penetration through the non -liquefiable clay layer and into the
liquefiable silty sand, in the vicinity of BH-1, we recommend that the invert depth be
established as high as practicable, particularly in the lower end of the system.
' Empirical relationships suggest that volumetric strains associated with soil liquefaction at this
site may be on the order of 1 to 3 percent, dependent on variability of soil conditions.
Conservatively assuming that soil confinement at depth will limit lateral straining, the
' estimated vertical displacements associated with liquefaction range from 1 to 5 inches.
However, the likely range of settlement would be of the order of 1 to 2 inches in our opinion.
Lateral spreading of the soils near the outlet channel is probable during the design seismic
event, inasmuch as the top of the liquefiable zone is near or within the base of the channel
banks. This lateral spreading could cause culvert joints to pull apart along the lower end of
the pipeline.
The cost of preventing liquefaction (i.e. installation of stone columns), or supporting the
culvert on piles to eliminate settlement or lateral spreading effects would exceed the costs of
repairs. Accordingly, these mitigation measures are considered unwarranted.
4.2.2 Subgrade Conditions
For most of the alignment, it is anticipated that the trench base for the box culvert will expose
medium stiff to stiff clay at foundation level, which will be suitable for support of the
proposed culvert. Soft peat and organic silt were encountered at borehole BH-2, near the
settled catch basin. The recent camera survey by the City of the 12-inch sanitary line,
coupled with our review of site contours and additional borehole information, suggests that
the soft peat and organic silt deposits exist as a relatively narrow buried channel infill. This
subsurface channel feature appears to be of the order of 160 feet in width and appears to trend
in a general northwest -southeast direction toward One Renton Place. Based on our borehole
information and the camera survey, we believe that the northerly edge of the channelized soft
deposits lies just to the north of the 12-inch sanitary line under -crossing of the existing
42-inch concrete line. Our boring BH-2 and the existing storm manhole appear to lie in
approximately the middle of this inferred channel of compressible materials.
2006-067 Rev Final2.doc 8 HWA GEOSCIENCES INC.
January 12, 2007
HWA Project No. 2006-067-21
To provide for a suitable foundation bearing layer, we recommend that the trench be over -
excavated 2 feet where organic soils are present at or within 2 feet of bottom of culvert (see
Figure 4, Trench Subgrade Preparation). To minimize disturbance to the foundation
subgrade during excavation, the excavator should use a smooth -edged bucket rather than a
toothed bucket. The over -excavated soil should be replaced with 2 feet of controlled density
fill (CDF) comprising a foamed concrete, as discussed in Section 4.2.3. We anticipate
approximately 160 feet of trench (for the preferred alignment shown on Figure 2) will require
this treatment, based on the borehole logs, the observed asphaltic concrete pavement cracking
and settlement in the vicinity, and the recent camera survey by the City. Another alternative
alignment closer to the One Renton Place building was considered in order to reduce the
length of alignment over peat. However, in view of the additional borehole (BH-5, BH-6,
and BH-7) findings, it is evident that peat underlies the easternmost alternative alignment as
well and may, in fact, represent a total lineal extent greater than that affecting the initially
preferred alignment. Hence, we understand that the initially preferred alignment will be
maintained for the proposed new system.
In areas beyond the limits of the organic soils, it would be acceptable to employ 1 '/4-inch
minus crushed rock as the foundation bearing layer, and the depth of over -excavation may be
reduced to 1 foot for this support layer (see Figure 4). In transition zones between over -
excavated sections within poorer subgrade areas, the base of the over -excavated areas should
taper uniformly at no steeper than 5H:1 V (Horizontal:Vertical) to the areas where over -
excavation is not required. Abrupt steps in the over -excavation intervals should be avoided.
The crushed rock should conform to the requirements outlined in Section 9-03.9 (1) Ballast,
of the 2006 WSDOT Standard Specifications. The replacement fill should extend to 3 feet
on either side of the culvert. The crushed rock should be compacted in lifts of about 12
inches with a vibratory plate compactor, or by static rolling with a small drum compactor.
Compaction should be discontinued if pumping of the pad and underlying subgrade becomes
apparent.
We prefer CDF as the bearing material throughout since its use prevents disturbance to the
supporting subgrade soils beneath the new culvert and its foundation system. In this latter
regard, we anticipate that the foundation system will comprise precast concrete slab sections
that may be supported on a thin (6 inches or less) granular leveling course, placed on the
CDF, or directly on the structural fill.
4.2.3 Estimated Settlement
We have analyzed the City's camera survey data, which indicates that the maximum
settlement of the 12-inch sanitary sewer line has been of the order of 2 to 2.5 feet, assuming
that it was initially installed on a linear uniform profile between the manhole intervals
surveyed. This maximum sag occurs roughly in the same area as the adjacent storm manhole,
which appears to have settled at least 1.78 feet, based on an assumed level pipe invert profile
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between manhole and outfall. As indicated previously, the location of maximum settlement
appears to be in the approximate center of what is inferred to be a subsurface or buried
channel infilled with compressible organic silt and peat deposits. Boring BH-2 is in this area
and indicates some 15.5 feet of compressible soils, which are overlain by a combined 8.5 feet
of fill and alluvium of much lower compressibility. The fill thickness appears to be of the
order of 3 feet at this location, and reduces to about 1-foot thickness at BH-1 to the south.
Although we do not know the timing of construction of the sewer and the parking lot in this
location, it seems apparent to us that the fill was placed for the parking lot development after
the sewer line had been constructed. The added weight of 3 feet of granular fill would have
induced loading of the compressible organic silt and peat and would have generated
consolidation of these deposits, accompanied by settlements of the sewer line which is
located at about 7 to 8 feet in depth in this location. Whereas the existing surface features of
the parking lot do not immediately suggest this degree of surface settlement, available ground
profiles along the existing storm line and sanitary sewer tend to support this conclusion.
To determine whether 3 feet of fill could generate this order of settlement, we undertook
settlement calculations based on the soil profile at BH-2 and assumed consolidation
parameters for the various soil units, based on our experience. Our analyses indicate that
from 18 to 23 inches (1.5 to 1.9 feet) would be generated by 3 feet of granular fill placed over
the soil profile observed in BH-2, which we consider to be generally in good agreement with
the settlement observations that have been made on both the existing sanitary and storm
sewer lines. Our recent consolidation testing of a sample of the peat from BH-5, which we
consider to likely be representative of the peat deposit in this area, confirms the consolidation
parameters initially assumed for this material. Recalculation of the settlement with the new
parameters provided an estimated amount of 17 inches. The additional laboratory testing has
also confirmed that the deposit is normally consolidated under existing site conditions. In
our opinion, this tends to support the assumption that the parking lot development occurred
after installation of both sewer lines and consisted of filling the site area to provide for
suitable grades. It also demonstrates that the existing organic silt and peat deposits are highly
compressible and will undergo significant additional settlement if loaded to any significant
degree.
For static conditions, it is anticipated that the net loading contributed by the new culvert
section and backfill can be proportioned in such a manner as to approximately balance that
removed in the form of excavated soil and fill materials that are present along the proposed
alignment. Consequently, theoretical settlement for the culvert section should be zero.
However, the amount of loading that is experienced at and below the culvert invert level will
depend to a significant degree on the contractor's trench excavation methods. If a broad,
unbraced, sloped trench excavation is employed, it is possible that the combined weight of
the culvert section and backfill materials could, in fact, generate a net pressure increase on
the soils supporting the proposed new culvert. We estimate that this net increase could
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amount to as much as 300 psf at the base of the culvert bearing layer. Conversely, if the
trench is braced and excavated with vertical walls to the limits necessary to place the bearing
material and culvert, the backfill requirements will be substantially reduced and would
provide for a small (estimated at less than 25 psf) unloading effect. Our estimate of
settlement for these localized loading conditions indicates that the induced settlement could
range from the order of 10 inches for the 300 psf loading level to zero for the latter case.
In view of the uncertainties associated with trench excavation and backfilling methodologies
that the contractor may employ, we recommend that it would be beneficial to consider use of
light -weight materials for trench backfill, at least through the alignment section underlain by
compressible organic silt and peat deposits. Moreover, subgrade disturbance during
construction oftentimes results in soil recompression effects which manifest themselves in
settlement of the newly installed pipe section. To prevent or mitigate this potential
occurrence, it will be necessary to prevent subgrade disturbance during excavation,
dewatering, pipe placement and backfilling to the extent practicable. To this end, use of CDF
for foundation support material will limit subgrade disturbance to the maximum degree and
be conducive to reduction of recompression settlement effects.
With regard to the CDF material, we believe that it would be of further benefit to employ a
foamed concrete product that can be mixed and installed with a substantially reduced unit -
weight. Elastizell is such a product that we have experience with and can be produced on site
in a wide range of unit weights ranging from about 30 to 110 pcf, with strengths ranging from
the order of 150 to 1500 psi. We recommend use of an Elastizell, or equivalent foamed
concrete, mix with unit weight of the order of 60 pcf, providing a strength in the range of 300
to 500 psi. Our research indicates that there is a local supplier of this material and costs are
reported to be somewhat higher than conventional CDF, depending on volume of product
required.
Elastizell or foamed concrete could be placed as backfill around the pipe section as well, but
is likely too costly for this purpose, and we suggest that bottom ash be considered as a light-
weight alternative for backfill of the pipe zone and to within about 2 feet of finished grade.
Our experience with this material indicates that it has a maximum compacted dry density of
the order of 75 pcf, and for this project could be suitably compacted to about 95 pcf wet
density. Again, we recommend that this treatment be considered for that section of culvert
alignment crossing the compressible area to mitigate potential future settlements. The
remainder of the culvert alignment should be amenable to conventional foundation and
backfill treatment recommended herein, and settlements should be limited to tolerable levels
if good construction practices are employed.
Estimated settlement for seismic conditions is discussed in Section 4.2.1. These potential
settlements will not be mitigated by the use of light -weight materials for pipe support and/or
backfill, but will neither be exacerbated.
2006-067 Rev Finalldoc 11 HWA GEOSCIENCES INC.
January 12, 2007
HWA Project No. 2006-067-21
' 4.3 LATERAL EARTH PRESSURES
For determination of lateral earth pressure design parameters, we have assumed that the
' existing fill and native soils will be removed and replaced with a suitable granular backfill.
We have further assumed that the backfill adjoining/above the walls of the culvert will be
placed to a horizontal condition at its surface and is compacted to the requirements provided
' for in Section 4.6.
On the basis of an assumed wet unit weight of 125 pcf for the backfill and a friction angle of
not less than 35 degrees, and seismic parameters appropriate for this site, we recommend the
following equivalent fluid unit weights for a variety of potential design conditions. The earth
pressure parameters presented in the first column are also based on fully -drained (dry)
conditions, or on conditions where the water levels within and exterior to the culvert are the
same or balanced. That is, the culvert is not anticipated to be water tight and, if the water
' table rises, it is anticipated to infiltrate the pipe and maintain an equilibrium hydrostatic
pressure condition on the culvert walls. More likely, water levels within the pipe will be
somewhat higher than the adjoining water table, when storm runoff flows are being handled
' by the culvert. In the extreme and most unlikely case that the pipe were to be dry and the
backfill became flooded to the surface, buoyant conditions would apply and the second
column of values provides the lateral earth pressures that would apply for design
' considerations. In our view, however, the pipe section should be considered a rigid element
and we recommend that the static, at -rest, earth pressure value under balanced hydrostatic
conditions be utilized for design of the culvert elements.
Loadin1l Condition Equivalent Fluid Unit WeilZht (pef)
' Dry or Balanced State Buoyant State
Active — Static (KA) 35 80
Active — Seismic (KAE) 40 85
1 At Rest — Static (Ko) 55 90
At Rest — Seismic (KOE) 80 100
' Passive - Static (KP) 460 295
' Passive - Seismic (KPE) 435 280
It is also to be noted that the earth pressure parameters are unfactored or ultimate values. If
' passive earth pressure conditions need to be considered in respect to lateral restraint of the
culvert section, an appropriate factor of safety (FS = 1.5) should be applied to the passive
' forces and we also recommend an allowable coefficient of sliding resistance equal to 0.45
2006-067 Rev Finalldoc 12 HWA GEOSCIENCES INC.
' January 12, 2007
HWA Project No. 2006-067-21
between foundation base slabs and underlying granular soils for determination of sliding
resistance.
' 4.4 EXCAVATION STABILITY AND SHORING
' 4.4.1 General
Excavation for the storm sewer can be accomplished with conventional equipment such as
backhoes and trackhoes. The excavation is anticipated to have a maximum depth on the
' order of 8 to 10 feet.
Maintenance of safe working conditions, including temporary excavation stability, is the
responsibility of the contractor. All temporary excavation in excess of 4 feet in depth must
be sloped in accordance with Part N of WAC (Washington Administrative Code) 296-155, or
' be shored. The near surface materials generally classify as Type C soil, for which WAC
requires that unsupported excavation walls must be inclined no steeper than 1.5H:IV, but
flatter slopes may be necessary because of water seepage. With time and the occurrence of
' seepage and/or precipitation, the stability of temporary unsupported cut slopes may be
significantly reduced.
4.4.2 Shoring
We recommend the use of shoring in order to reduce impacts to adjacent utilities, minimize
the volume of excavation spoils and backfill, and minimize the area of pavement to be
restored. It should be recognized that trench boxes do not typically act as excavation slope
shoring, but serve as protection for workers operating within the confines of the excavation.
If trench boxes are used on this project, sloughing of excavation slopes may be anticipated
resulting in potential disturbance to areas and facilities adjoining the open trenches where
they are deployed. We understand that for the nearby 7t' Street storm sewer replacement,
trench boxes were used with steel sheets installed just outside the boxes and pushed deeper
into the soil.
' Sheet piles are not anticipated to be required, except perhaps in localized areas where it may
be necessary to restrict the excavation to tight limits and prevent any potential for collapse of
1 trench walls. In this condition, care will be essential to prevent potential damage to adjoining
facilities from vibrations during pile driving.
' If required, we recommend that the design of temporary shoring should be based on a
uniform lateral pressure distribution of 25H psf (where H is the depth of the excavation in
feet). This pressure does not include any surcharges due to equipment or materials near the
' shoring and assumes that water pressures do not act above the base of the excavation.
Dewatering may be necessary to achieve this ground water condition.
2006-067 Rev Finalldoe 13 HWA GEOSCIENCES INC.
January 12, 2007
HWA Project No. 2006-067-21
4.5 DEWATERING
Design and implementation of temporary project dewatering systems is typically the
responsibility of the contractor. Soils and ground water information that the contractor may
use for design of his dewatering system needs are presented herein. However, within the
scope of this investigation, we have made some preliminary assessments of ground water
conditions at the site and potential dewatering requirements.
We anticipate ground water will be present to approximately 3 to 7 feet above the trench
invert elevation (including peat sections with 2 feet of over -excavation) along the planned
trench section. We expect that much of the dewatering should be able to be accomplished
with localized sumps. The use of localized short-term sumps for dewatering would minimize
potentially damaging settlements to adjacent utilities and pavements that can occur with
dewatering wells in such soil conditions. Well points may, however, be needed in the
vicinity of BH-4. For bidding purposes, we estimate that well points should be assumed for
approximately one-fourth of the alignment. In the event that greater need for well point
dewatering proves to be necessary, we recommend that a dewatering contingency allowance
be included in the project contract.
Dewatering volumes will likely vary along the trench alignment, due to the variability of
geologic conditions, and depending on ground water levels at the time of construction. Based
on the available site information and HWA's limited testing program, an estimated
dewatering requirement of approximately 1 to 15 gallons per minute (gpm) per 100 feet of
trench is expected (see Table 3, Appendix A for projected pumping rates). Discharge flows
are expected to be the highest along the north end of the alignment. Additionally, a wider
trench (14 feet) for the twin 48-inch pipe option would require slightly higher dewatering
volumes.
Soils in the vicinity of BH-4 are silty sands, and ground water may be under a slight
confining condition. Soils in the vicinity if BH-3 and BH-2, in the central portion of the
proposed alignment, consist primarily of fine-grained soils (peat, clay and silt) overlying a
' thin (less than five feet thick) layer of silty sand. Piezometers were not completed in these
borings, but dewatering needs in this vicinity will likely be less than those in the vicinity of
BH-4. The transition from silty soils to weathered sandstone occurs somewhere between BH-
' 2 and BH-1. One concern in the vicinity of the southern end of the proposed alignment will
be the recharge influence from the open channel which the stormwater system empties into.
However, due to the low permeabilities of the weathered sandstone in the vicinity, there is a
low likelihood that significant recharge will occur from the channel, and pumping rates
beyond the highest estimated rates (Table 3, Appendix Q are not expected.
The dewatering rates were calculated for water levels measured during June of 2006.
Seasonal variability in ground water elevations is expected and dewatering requirements
during wet seasons will likely be higher.
2006-067 Rev Finalldoc 14 HWA GEOSCIENCES INC.
January 12, 2007
HWA Project No. 2006-067-21
' Where excessive seepage infiltration is experienced, construction dewatering is important
because it will be very difficult to maintain stable slopes, prepare subgrade, evaluate
subsurface conditions, and construct structures in the wet. In addition, upward seepage into
' the excavation base can cause sand boils and/or heaving. This is likely to be of greater
concern in the southern section of the line (i.e., south of BH-2), where ground water is likely
to be present in the silty sand and organic materials anticipated at or near proposed invert
depths. In this section, we recommend that the proposed excavation be dewatered to
maintain the ground water level at least 3 feet below the base of the excavation, and
dewatering measures should be implemented before excavation to final subgrade level
begins. Dewatering should continue until the culvert has been placed and backfilled, and is
capable of resisting hydrostatic forces. Disposal of water will be a consideration that will
' have to be suitably resolved with environmental and fisheries agencies having jurisdiction.
The need for well points is dependent on the depth of the excavation, volume of ground water
seepage, and potential presence of boiling or quick conditions in the excavation base. The
latter condition will need to be evaluated at the time the excavation is undertaken, as it will
depend on the shoring methods and dewatering measures implemented by the contractor.
Construction dewatering requirements will also depend on the time of year, water level in the
discharge channel, recent rainfall and other factors. For this reason, we recommend
construction should be performed during the dry season.
The contractor should be made aware that, if the ground water is lowered by more than about
7 to 10 feet below current elevations for significant periods, settlement of nearby facilities
could occur. We recommend that settlement of nearby facilities such as the sanitary sewer be
monitored using optical survey methods during the period of any dewatering. Piezometers
' installed as part of the geotechnical investigation should be left in place to monitor seasonal
changes in ground water levels, and to monitor ground water levels during construction
dewatering, in order to assure that dewatering is not excessive, and potential settlement of
' organic soils does not occur at the site. Additionally, it is recommended that ground water
monitoring wells or piezometers be installed between the works and adjoining critical
1 facilities to permit observation of ground water levels. Should potentially adverse drawdown
and/or settlements become apparent, it may be necessary to suspend the dewatering
operations until mitigation measures, such as re -injection wells are designed and
' implemented.
' 4.6 BACIFILL PLACEMENT AND COMPACTION
Trench and culvert backfill should consist of Gravel Backfill for Walls, as described in
Section 9-03.12(2) of the 2006 WSDOT Standard Specifications, and be compacted in lifts to
95 percent of Modified Proctor dry density (ASTM D:1557).
2006-067 Rev Finalldoc 15 HWA GEOSCEENCES INC.
' January 12, 2007
HWA Project No. 2006-067-21
' During placement of the initial lifts, the backfill material should not be bulldozed into the
excavation or dropped directly on the structure. Furthermore, heavy vibratory equipment
should not be permitted to operate directly over the structure until at least 2 feet of material is
1 present above the crown of the culvert section, unless otherwise approved by the structural
engineer.
' The procedure to achieve proper density of compacted fill depends on the size and type of
compaction equipment, the number of passes, thickness of the layer being compacted, and
' soil moisture -density properties. If access or load considerations restrict the use of heavy
equipment, smaller equipment can be used, but the soil must be placed in thin enough lifts to
achieve the required compaction. If granular material has been employed for foundation
support of the pipe, care must be exercised in the lower levels of the pipe backfill to prevent
excessive compaction and potential disturbance to the foundation material and subgrade soils.
4.7 EROSION CONSIDERATIONS
Erosion of exposed soils can be minimized by careful grading practices, the appropriate use
of silt fences and/or straw bails and use of surface cover materials, as appropriate.
Surface runoff control during construction should be the responsibility of the contractor, and
should be treated prior to discharge to a permanent discharge system such as a storm sewer,
so as to comply with State water quality standards. Water from sumps will also require
treatment prior to discharge to the storm sewer. Permanent control of surface water should
be incorporated in the final grading design. Water should not be allowed to pond
immediately adjacent to foundations or paved areas. Grading measures, slope protection,
ditching, sumps, dewatering, and other measures should be employed as necessary to permit
proper completion of the work.
5.0 CONDITIONS AND LIMITATIONS
We have prepared this report for use by Gray & Osborne and the City of Renton for design of
a portion of this project. This report should be provided in its entirety to prospective
contractors for bidding or estimating purposes; however, the conclusions and interpretations
presented should not be construed as our warranty of the subsurface conditions. Experience
has shown that subsurface soil and ground water conditions can vary significantly over small
distances. Inconsistent conditions can occur between explorations and may not be detected
by a geotechnical study. If, during future site operations, subsurface conditions are
encountered which vary appreciably from those described herein, HWA should be notified
for a review of the recommendations of this report, and provide revisions, if necessary.
2006-067 Rev Finalldoc 16 HWA GEOSCIENCES INC.
January 12, 2007
HWA Project No. 2006-067-21
We recommend that HWA be retained to review the plans and specifications and to monitor
the geotechnical aspects of construction, particularly construction dewatering, excavation,
subgrade preparation, bedding and backfill placement and compaction.
HWA does not practice or consult in the field of safety engineering. We do not direct the
contractor's operations, and we cannot be responsible for the safety of personnel other than
our own on the site; the safety of others is the responsibility of the contractor. The contractor
should notify the owner if he considers any of the recommended actions presented herein
unsafe.
2006-067 Rev Final2.doc 17 HWA GEOSCIENCES INC.
January 12, 2007
HWA Project No. 2006-067-21
Mom.
We appreciate this opportunity to be of service.
Sincerely,
HWA GEOSCIENCES INC.
Brad W. Thurber, L.E.G.
Engineering Geologist
EXPIRES 08 / 24 / 08
Lorne A. Balanko, P.E.
Geotechnical Engineer/President
BWT:LAB:bwt
of W ash;
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Hydrogeol i pj
170 0
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Arnon Sugar
Arnie Sugar, L.G., L.H.G.
Vice President
2006-067 Rev Final2.doe 18 HWA GEOSCIENCES INC.
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' HWAGEOSCIENCES INC.
IMPROVEMENTS
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PROJECT NO.
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PREPERATION DATE 1PROJECT NO.
10.27.06 12006-067-21
Appendix A
APPENDIX A
FIELD INVESTIGATION
APPENDIX A
IFIELD INVESTIGATION
The field exploration program was performed in two phases; the original scope of work
and a supplemental scope that was requested based on findings of the initial phase. Four
boreholes (designated BH-1 through BH-4) were drilled on June 2nd and 13'h, 2006, and
' three boreholes (designated BH-5 through BH-7) were drilled on December 8, 2006. All
drilling was conducted by Holocene Drilling, Inc. of Fife, Washington, under subcontract
to HWA. The boreholes were advanced using a Mobile B-59, truck -mounted, drill rig
employing hollow -stem auger. The borehole locations were determined approximately in
the field by pacing and taping distances from existing site features, after completion of
drilling, and are indicated on the site and exploration plan, Figure 2.
An engineering geologist from HWA supervised and logged the explorations and
recorded pertinent information including sample depths, stratigraphy, soil engineering
characteristics, and ground water occurrence. The boreholes were drilled and sampled to
depths between 21.5 feet and 36.5 feet. At select intervals within each borehole, Standard
' Penetration Test (SPT) sampling was performed using a 2-inch outside diameter split -
spoon sampler and a 140-pound auto -hammer. During the SPT test, a sample is obtained
by driving the sampler 18 inches into the soil with the hammer free -falling 30 inches.
The number of blows required for each 6 inches of penetration is recorded. The Standard
Penetration Resistance ("N-value") of the soil is calculated as the number of blows
required for the final 12 inches of penetration. This resistance, or N-value, provides an
indication of relative density of granular soils and the relative consistency of cohesive
soils. Relatively undisturbed samples of compressible soils (peat) were obtained from
boreholes BH-5 and BH-6 by pushing 3-inch diameter, 30-inch long, steel Shelby tubes
into the soil at selected depths.
At the completion of boreholes BH-1 and BH-4, piezometers or monitoring wells,
consisting of 2-inch diameter PVC pipe, were installed. The piezometers were finished
' with flush -mounted surface monuments. Well completion details are indicated on the
individual borehole logs. Ground water levels in the piezometers were measured on
June 16 and 23, 2006. The other boreholes were abandoned with bentonite chips upon
' termination of drilling, and the pavement was patched with concrete.
Soil samples were classified in the field and representative portions placed in plastic bags.
1 Two Shelby tube samples were sealed with plastic caps and duct tape. These soil samples
were returned to our laboratory for further examination and testing. The sampled soils
were classified in general accordance with the classification system described in
Appendix A on Figure A-1. A key to the borehole log symbols is also presented in Figure
2006-067 Rev Finalldoc A-1 HWA GEOSCIENCES INC.
' A-1. The borehole logs are presented as Figures A-2 through A-8, and should be
referenced for specific subsurface details at the borehole locations. However, the
stratigraphic contacts shown on the logs represent the inferred boundaries between soil
types, and may be gradational in nature and much less distinct than represented.
2006-067 Rev Final2.doc A-2 HWA GEOSCIENCES INC.
RELATIVE DENSITY OR CONSISTENCY VERSUS SPT N—VALUE
COHESIONLESS SOILS
COHESIVE SOILS
Approximate
Density
N (blows/ft)
Approximate
Consistency
N (blows/ft)
Undrained Shear
Relative Density(%)
Strength (psf)
Very Loose
0 to 4
0 - 15
Very Soft
0 to 2
<250
Loose
4 to 10
15 - 35
Soft
2 to 4
250 - 500
Medium Dense
10 to 30
35 - 65
Medium Stiff
4 to 8
500 - 1000
Dense
30 to 50
65 - 85
Stiff
8 to 15
1000 - 2000
Very Dense
over 50
85 - 100
Very Stiff
15 to 30
2000 - 4000
Hard
over30
>4000
USCS SOIL CLASSIFICATION SYSTEM
MAJOR DIVISIONS
GROUP DESCRIPTIONS
Coarse
Grained
Soils
Gravel and
Gravelly Soils
Clean Gravel
(little or no fines)
•'
GW
Well -graded GRAVEL
o C�
GP
Poody-graded GRAVEL
More than
50% of Coarse
Gravel with
oc
GM
Silty GRAVEL
Fraction Retained
Fines (appreciable
on No. 4 Sieve
amount of fines)
GC
Clayey GRAVEL
Sand and
Clean Sand
SW
Well -graded SAND
More than
Sandy Soils
(little or no fines)
$P
Poorly -graded SAND
50% Retained
on No.
50% or More
of Coarse
Sand with
$M
Silty SAND
200 Sieve
Size
Fraction Passing
No. 4 Sieve
Fines (appreciable
amount of fines)
SC
Clayey SAND
ML
SILT
Fine
Silt
CL
Lean CLAY
Grained
Soils
and Liquid Limit
Less than 50 %
Clay
_
7-
OL
Organic SILT/Organic CLAY
MH
Elastic SILT
50% or More
Passing
No. 200 Sieve
Silt
and Liquid Limit
CIa 50% or More
y
CH
Fat CLAY
Size
OH
Organic SILT/Organic CLAY
Highly Organic Soils
PT
PEAT
COMPONENT DEFINITIONS
COMPONENT
SIZE RANGE
Boulders
Larger than 12 in
Cobbles
3 in to 12 in
Gravel
3 in to No 4 (4.5mm)
Coarse gravel
3 in to 3/4 in
Fine gravel
3/4 in to No 4 (4.5mm)
Sand
No. 4 (4.5 mm) to No. 200 (0.074 mm)
Coarse sand
No. 4 (4.5 mm) to No. 10 (2.0 mm)
Medium sand
No. 10 (2.0 mm) to No. 40 (0.42 mm)
Fine sand
No. 40 (0.42 mm) to No. 200 (0.074 mm)
Silt and Clay
Smaller than No. 200 (0.074mm)
TEST SYMBOLS
%F
Percent Fines
AL
Atterberg Limits: PL = Plastic Limit
LL = Liquid Limit
CBR
Califomia Bearing Ratio
CN
Consolidation
DO
Dry Density (pcf)
DS
Direct Shear
GS
Grain Size Distribution
K
Permeability
MD
Moisture/Density Relationship (Proctor)
MR
Resilient Modulus
PID
Photoionization Device Reading
PP
Pocket Penetrometer
Approx. Compressive Strength (tsf)
SG
Specific Gravity
TC
Triaxial Compression
TV
Torvane
Approx. Shear Strength (tsf)
UC Unconfined Compression
SAMPLE TYPE SYMBOLS
2.0" OD Split Spoon (SPT)
(140 lb. hammer with 30 in. drop)
IShelby Tube
3-1/4" OD Split Spoon with Brass Rings
OSmall Bag Sample
Large Bag (Bulk) Sample
u Core Run
L�I Non-standard Penetration Test
(3.0" OD split spoon)
GROUNDWATER SYMBOLS
Z7 Groundwater Level (measured at
time of drilling)
1 Groundwater Level (measured in well or
open hole after water level stabilized)
COMPONENT PROPORTIONS
PROPORTION RANGE
DESCRIPTIVE TERMS
<5%
Clean
5 - 12%
Slightly (Clayey, Silty, Sandy)
12 - 30%
Clayey, Silty, Sandy, Gravelly
30-50%
Very (Clayey, Silty, Sandy, Gravelly)
Components are arranged in order of increasing quantities.
NOTES: Soil classifications presented on exploration logs are based on visual and laboratory observation.
Soil descriptions are presented in the following general order:
Density/consistency, color, modifier (if any) GROUP NAME, additions to group name (if any), moisture
content. Proportion, gradation, and angularity of constituents, additional comments.
(GEOLOGIC INTERPRETATION)
Please refer to the discussion in the report text as well as the exploration logs for a more
complete description of subsurface conditions.
MOISTURE CONTENT
DRY Absence of moisture, dusty,
dry to the touch.
MOIST Damp but no visible water.
WET Visible free water, usually
soil is below water table.
LEGEND OF TERMS AND
' Renton Village Storm System Improvement Project SYMBOLS USED ON
HWAGEOSCIENCES INC. Renton, Washington EXPLORATION LOGS
' PROJECT NO.: 2006-067 FIGURE: A-1
LEGEND 2006-067.GPJ 1/12/07
ii"
DRILLING COMPANY: Holocene Drilling SURFACE ELEVATION: 26.00 f feet DATE STARTED: 6/13/2006
DRILLING METHOD: HSA, Mobile B-59 DATE COMPLETED: 6/13/2006
SAMPLING METHOD: SPT w/autohammer LOGGED BY: D. Huling
LOCATION: See Figure 2
UU))
W
w
U
CoLu
U
}
7
U~j v
UU))
W U
J
O
I-
Z
w Q
w
w
ui
tz
a
c"))
z o
=
N x
o
U)
DESCRIPTION U))
V))
a 8
O
a Lo 0
0�
5-
1 10-
1 15-
1 20-
1 25 -
1 30 -
SM
4 inches A.C.P., over 3 inches crushed rock.
Medium dense, brown, silty SAND, most.
xi
CL
A STRUCTURAL FILL
S-1a AL
/
0
CL
Medium stiff, dark brown, silty CLAY, moist.
BURIEDTOPSOIL
S-1b 3-4-4
Medium stiff, heavily rust -banded, light brown, silty CLAY,
moist. Trace organics. Grades to blue -gray.
(RECESSIONAL.GLACIOLACUSTRINE) .............
CH
Soft, brown grading to gray, fat CLAY, moist. Trace organics.
Grades to medium plasticity.
A S-2 1-2-2 AL
i
SM
Medium dense, brown, silty, fine to medium, SAND, wet.
Finely bedded.
�/� S-3 3-10-12 GS
______________________
—weal
S-4 3-3-5
ML
Medium stiff, brown, clayey SILT, moist. interbedded
layer of non -plastic silt present, scattered weathered fine
SM
ravel.
Medium dense, brown, silty fine SAND, moist, scattered fine
S-5 7-10-14 GS
gravel and coarse sand mostly consisting of highly weathered
sandstone, massive bedding. Note: Portion of sand grains
crumble to silt with finger pressure; grain size analysis caused
breakdown to sandy SILT.
(SANDSTONE: RENTON FORMATION)
S-6 6-12-16
Started adding water to auger at 11' to prevent heave.
SM
— — — — — — — — — — — — — — —
Very dense, off-white, silty, fine to medium SAND, moist.
S-7 13-23-33 GS
Weathered sandstone, with heavy oxidation in top few inches
of sample.
As above, with top 8 inches oxidized, and 1 cm thick clay
S-8 23-23-40
layer, possible small scale perched water table.
Borehole terminated at 21.5 feet below the ground surface.
Ground water seepage observed at approx. 7.5 feet below the
ground surface.
I NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated
l` and therefore may not necessarily be indicative of other times and/or locations.
Standard Penetration Test
(140 lb. weight, 30" drop)
A Blows per foot
x
H
10 20 30 40 50 O
�....
...���.
5
A
...�.......:....:....:....
.... ....
10
A.
0.
... ....
....
.A:.... ....:.... ....
15
f
20 1
I I-25 1
`30
0 20 40 60 80 100
Water Content (%)
Plastic Limit 1--0 Liquid Limit
Natural Water Content
BORING:
Renton Village Storm System Improvement Project BH-1
HWAGEOSCIENCES INC Renton, Washington PAGE: 1 of 1
PROJECT NO.: 2006-067 FIGURE: A-2
PZO 2006-067.GPJ 1110/07
DRILLING COMPANY: Holocene Drilling LOCATION: See Figure 2
DRILLING METHOD: HSA, Mobile B-59 DATE STARTED: 6/13/2006
SAMPLING METHOD: SPT w/autohammer DATE COMPLETED: 6/13/2006
SURFACE ELEVATION: 27 t feet LOGGED BY: D.Huling
M
W
1 21
1 2
3
DESCRIPTION
�'
GW
4 inches A.C.P. over 6 inches crushed rock.
Dense, brown, slightly sandy rounded to sub -rounded, coarse,
GRAVEL, moist.
46 1(
FILL)
t
SM
Medium dense, gray, slightly fine gravelly, very silty SAND,
moist to wet. Trace fibrous organics.
(ALLUVIUM)
Soft, dark brown, organic SILT, wet, fibrous organic material,
OH
high dilatancy, organic at various levels of decomposition.
At 10 feet, Organic Content = 13.0%.
.....................................................................
Soft, dark brown, PEAT, wet, large tree roots, organics less
PT
decomposed.
At 15 feet, Organic Content = 45.8%
...........................................................
OH
Soft, dark brown grading to gray, organic SILT, wet, grades to
sandy.
Loose, dark grayish brown, silty fine SAND, moist to wet.
SM
-----------------------
Soft, dark brown, organic SILT, moist to wet, fibrous organics
OH
Stiff, light blue, silty CLAY, moist, trace fibrous organics.
V
(RECESSIONAL GLACIOLACUSTRINE)
Qf
m
w
U
z
w
Standard Penetration Test
a 2
H
4
(140 lb. weight, 30" drop)
o
Blows per foot
w w
w co
I-
z
_
a s
N
w
D
2 2
z
=
O
IL
o
v¢) 0
a a
O
O
0 10
20 30 40
50
O
0
S-1
19-13-23
+....
•
5
S-2
6-7-7
GS
..
,
S-3
2-5-4
A °....:....
....:.... .... .... .... ....:�..
10
S 4
Ix..........
0-0-3
OC
........ ..
........
........................:....:....:....:....:34
♦:
TA S5
653
31
�....
.... .... ....:.... ....:....
..
15
S-6
0-2-2
oc
S-7
1-0-1
..
..�..
20
S-8
2-4-2
GS
�.....:....:....:...�....
.... ....
..
25
S9
234
For a proper understanding of the nature of subsurface conditions, this 0 20 40 60 80
exploration log should be read in conjunction with the text of the Water Content (%)
geotechnical report. Plastic Limit 1— 0 Liquid Limit
Natural Water Content
NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated
and therefore may not necessarily be indicative of other times and/or locations.
� �30 I
100
BORING:
Renton Village Storm System Improvement Project BH-2
HWAGEOSCIENCES INC. Renton, Washington PAGE: 1 of 2
PROJECT NO.: 2006-067 FIGURE: A-3
BORING 2006-067.GPJ 1/10/07
DRILLING COMPANY: Holocene Drilling
DRILLING METHOD: HSA, Mobile B-59
SAMPLING METHOD: SPT w/autohammer
SURFACE ELEVATION: 27 f feet
LOCATION: See Figure 2
DATE STARTED: 6/13/2006
DATE COMPLETED: 6/13/2006
LOGGED BY: D.Huling
co
g
0-1
LU
w
Z
w Standard Penetration Test
U
a
m
2
1-- L
II—
¢ (140 lb. weight, 30" drop)
J
O
w e
o Blows per foot
J
co
J
w
J
2
Z
a, 2 0
�
z o
=
o
a s
w
w �, >- cn
0 Cl)D
DESCRIPTION
¢¢
m
V)
w—
a s
F
O
0 0 10 20 30 40
u
50 o w
30
ML
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Medium dense, blue -gray, sandy SILT, moist. Non -plastic.
—
S-10
0-5-4
AL
.... ........;......... ............... ...,....
30
35
....;....�....�.....:.... .... .... ....:....
35
S-11
5-6-11
GS
Borehole terminated at 36.5 feet below the ground surface.
Ground water seepage observed at approx. 2.5 feet below the
ground surface.
....:....:....:....:....:....:....:....:....:....
40
.... :.................................. :....:....
40
45
50
55
60 J
For a proper understanding of the nature of subsurface conditions, this
exploration log should be read in conjunction with the text of the
geotechnical report.
NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated
and therefore may not necessarily be indicative of other times and/or locations.
f— 50
H 55
0 20 40 60 80 100
Water Content (%)
Plastic Limit 1 0 ' Liquid Limit
Natural Water Content
BORING:
ULMRenton Village Storm System Improvement Project BH-2
HWAGEOSCIENCES INC. Renton, Washington PAGE: 2 of 2
PROJECT NO.: 2006-067 FIGURE: A-3
BORING 2006-067.GPJ 1/10/07
DRILLING COMPANY: Holocene Drilling LOCATION: See Figure 2
DRILLING METHOD: HSA, Mobile B-59 DATE STARTED: 6/2/2006
SAMPLING METHOD: SPT w/autohammer DATE COMPLETED: 6/2/2006
SURFACE ELEVATION: 29 f feet LOGGED BY: T. Taddese
Lo
W
U
O
Co 2
CL
co
0U) D
0-
5
IT
IE
21
2
0-1
m
w
z
w
Standard Penetration Test
a
F- s
N
Q
(140 lb. weight, 30" drop)
w e
L
o
A Blows per foot
w
0-
w
o
z
2
0-
g
z 3
Lu
i
O
~
a
o
DESCRIPTION N
U)
0- a
O
O
0
10 20 30 40
0
50
GP
3 inches A.C.P. over 4 inches crushed rock.
Medium dense, dark brown, slightly silty, fine to coarse,
o
subrounded, GRAVEL, moist.
�
FILL
SM
Medium dense, yellow -brown and gray, slightly gravelly, very
silty, fine SAND, moist.
I
--------1ALLUVIUJ---------
SM
Loose, gray and blue, silty, fine to medium SAND, scattered
gravel, moist. Dark brown silt in the bottom 4 inches of
sample.
CL
Medium stiff, light olive brown, plastic CLAY, moist. Abundant
organics (rotten horse tail), with lenses of fine sandy silt.
_ _ RECESSIONAL GLACIOLACUSTRINE
CL
Very stiff, blue gray grading to rust -mottled yellow brown,
plastic CLAY, moist. Scattered organics.
I
— —
Very stiff, light yellow brown, clayey, laminated SILT with
!�
ML
lenses of fine sand, moist.
Very stiff, rust mottled, olive brown to yellowish brown,
-------------------------
ML
laminated SILT, moist.
Grades to sandy SILT at about 16 feet below the ground
SM
`surface___________________
Medium dense, light olive brown, silty, fine SAND, wet.
i
1-inch thick lens of silty sand at approx. 19 feet.
— — — — — — — — — — — — — — — — — — — — — —
Dense, brown, silty, fine to medium SAND, wet. Finely
i
SM
bedded.
I
i
Medium dense, brown, silty, fine to medium SAND, moist to
wet.
Borehole terminated at 26.5 feet below the ground surface.
Ground water seepage observed at approx. 12.5 feet below
the ground surface.
3-1 4-10-10 GS
3-2 5-4-4
S-3 0-0-7 AL
S-4 5-8-11
S-5 5-8-10
S-6 5-6-11
S-7 2-8-15 GS
S-8 10-14-18
S-9 7-8-11
'-
.................................................
AD
r. ....
............
•:
..:....:....:......A.
...;....;....
7-0
-5
atom I
�1
-20 1
- 25 1
30 30
For a proper understanding of the nature of subsurface conditions, this 0 20 40 60 60 100
exploration log should be read in conjunction with the text of the Water Content (%)
geotechnical report. Plastic Limit 1 0' Liquid Limit
Natural Water Content
NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated
and therefore may not necessarily be indicative of other times and/or locations.
BORING:
Renton Village Storm System Improvement Project BH-3
HWAGEOSCIENCES INC. Renton, Washington PAGE: 1 of 1
PROJECT NO.: 2006-067 FIGURE: A-4
BORING 2006-067.GPJ 1/10/07
DRILLING COMPANY: Holocene Drilling SURFACE ELEVATION: 30.00 t feet DATE STARTED: 6/2/2006
DRILLING METHOD: HSA, Mobile B-59 DATE COMPLETED: 6/2/2006
SAMPLING METHOD: SPT w/autohammer LOGGED BY: T. Taddese
LOCATION: See Figure 2
U)
W
w
U
co
U
d
D
U L
H
rn
UJ
W U
J
O
Z
U) C
Lu
W
J
J
L
W o
ul
a
co co
V)
CL
�
Z 3
Ld
2
O Lu
2
°��
vi
F3
O
o
r}n
D
DESCRIPTION
U)
0-
a cUn 0
0
3.5 inches A.C.P. over 4 inches crushed rock.
GP
Medium dense, brown, slightly silty, sandy, fine to coarse
°
GM
GRAVEL, moist.
SM
FILL
Medium dense, grayish brown, silty, gravelly, fine to medium
S-1
16-13-7 GS
SAND, moist.
(ALLUVIUM)
5
CL
Medium stiff, brown, silty CLAY, moist. Laminated with
interbeds of fine sand and silt, moist.
S-2
4-6-9
(RECESSIONAL GLACIOLACUSTRINE)
................................................................
Very stiff, rust -mottled, yellow brown, silty CLAY, moist.
S-3
5-8-14 AL
CL
Laminated, with some fine sand interbeds.
10
;� S-4
4-6-9
SP
Medium dense, slightly rust mottled, light yellow brown, slightly
SM
silty, fine SAND, moist to wet. Driller started to add water to
avoid heaving of sand.
SP
..............
.... own, slighty silty,
Medium dense to dense, olive brown, sli htl silt ,fine to
I S-5
12-22-23 GS
SM
medium SAND, wet. Finelybedded.
�
15
S-6
5-7-12
S-7
7-12-15
20
S-8
I
7-9-14
25
S-9a 5-6-6
Stiff olive brown to green sandy, laminated SILT, moist. 3-9b GS
Borehole terminated at 26.5 feet below the ground surface.
Ground water seepage observed at approx. 10.5 feet below
the ground surface.
30
NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated
and therefore may not necessarily be indicative of other times and/or locations.
Standard Penetration Test
(140 lb. weight, 30" drop)
♦ Blows per foot
10 20 30 40
0 20 40 60 80
Water Content (%)
Plastic Limit 1--0 Liquid Limit
Natural Water Content
2
H
EL
w
50 0
r0
-5
-10
-15 1
-20
- 25 1
`30
100
BORING:
Renton Village Storm System Improvement Project BH-4
I WAGEOSCIENCES INC. Renton, Washington PAGE: 1 of 1
PROJECT NO.: 2006-067 FIGURE: A-5
PZO 2006-067.GPJ 1/10107
DRILLING COMPANY: Holocene Drilling LOCATION: See Figure 2
DRILLING METHOD: HSA, Mobile B-59 DATE STARTED: 12/8/2006
SAMPLING METHOD: SPT w/autohammer DATE COMPLETED: 12/8/2006
SURFACE ELEVATION: 28 t feet LOGGED BY: B. Thurber
U)
U
J_
J O
m cn
a 2 U
0-
ill
W
I=
1 2'
1 2
Of
m
w
U
z
w
Standard Penetration Test
a
F- L
F
Q
(140 lb. weight, 30" drop)
w S
-
o
Blows per foot
w
_1
w
J
m
W
z
2
2
2
z o
x
O
a 6
�U'
DESCRIPTION U)
W
d a
O
In nn An
an O
an
5 inches A.C.P.
GM
0
7
Medium dense, dark brown grading to blue -gray, silty, sandy,
fine to coarse GRAVEL, moist to wet.
---------LILLL---------
SM
Dense, brownish -gray, fine gravelly, silty fine SAND, moist.
Medium dense, olive -gray, fine gravelly, silty fine SAND,
moist.
PT
0
,
Soft, dark brown, fibrous PEAT with charcoal and wood
fragments.
(ALLUVIUM)
- - - - - - - - - - - - - - - -
OL
Soft grayish brown, organic SILT with charcoal and wood
fragments ryloist.---------------/
PT
0
Blow count overstated by driving sampler into >1 1/2-inch
diameter wood.
J
Soft, dark brown, fibrous PEAT with wood fragments, moist.
0,
Shelby tube sample attempted at 12.5 feet, no recovery.
0
—
Very soft, dark brown, fibrous PEAT, moist.
@ 13.75', lens of light gray, silty SAND, moist.
Very soft, dark brown, slightly silty, fibrous PEAT with wood
—
debris, moist. Two pieces of partly decomposed wood were
approx. 1 and 2 inches thick, the full width of Shelby tube.
- - - - - - - - - - - - - - - - - - - - - -
Loose, gray -brown, organic SILT with lenses of gray fine
I
M
SM
SAND, wet. ................. J
SP
Loose, gray, slightly silty, fine to medium SAND, wet, with
SM
lenses of dark brown PEAT.
Loose, gray, clean to silty (stratified), fine to medium SAND,
wet. With lenses of woody and fine organics, and a 2-inch
lens and 4-inch lens of woody PEAT.
Added water to aver after samelinn at 20 feet. - - - - -
SP
SM
Medium dense, yellow brown, slightly silty, fine to medium
SAND, wet. High -angle rust band.
i
Medium dense, dark yellow brown, slightly silty, fine to
medium SAND, wet. Broadly rust -banded.
S-1 3-14-19
S-2 4-6-10
S-3 3-3-3
S-4 0-8-2
i
S-5 0/18"
S-6
S-7 1-1/12"
i
I
S-8 0-1/12"
XS-9 4-5-7
CN
30
For a proper understanding of the nature of subsurface conditions, this
exploration log should be read in conjunction with the text of the
geotechnical report.
NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated
and therefore may not necessarily be indicative of other times and/or locations.
..:....:....:....
:......... :....
A
�-5
I-10 1
)-15
F 20
Ar 30
30
0 20 40 60 80 100
Water Content (%)
Plastic Limit 1 -0 Liquid Limit
Natural Water Content
BORING:
90, 1 Renton Village Storm System Improvement Project BH-5
HWAGECISCIENCES INC. Renton, Washington PAGE: 1 of 2
PROJECT NO.:. 2006-067 FIGURE: A-6
BORING 2006-067.GPJ 1/10/07
f DRILLING COMPANY: Holocene Drilling LOCATION: See Figure 2
DRILLING METHOD: HSA, Mobile B-59 DATE STARTED: 12/8/2006
SAMPLING METHOD: SPT w/autohammer DATE COMPLETED: 12/8/2006
SURFACE ELEVATION: 28 t feet LOGGED BY: B. Thurber
U)
w
Lu
U
Of
v
a
t
U
Q
~
Z
Lu
O
w
w
F
w
F
0
Z
CO
U)
ii
CL
N
w
D
as
c)
z o
=
O
Z)
o t-
V)
DESCRIPTION U)
U))
0-
O
0
0
30
Medium dense, rust-
banded olive brown, slightly silty, fine to 5-10 5-8-7
medium SAND, wet.
With 2 1/2-inch lens of finel bedded fine sand SILT.
Borehole terminated at 31.5 feet.
1 35 -
1 40-
1 45 -
1 50 -
1 55 -
1 60 -
For a proper understanding of the nature of subsurface conditions, this
exploration log should be read in conjunction with the text of the
geotechnical report.
NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated
and therefore may not necessarily be indicative of other times and/or locations.
Standard Penetration Test
(140 lb. weight, 30" drop)
♦ Blows per foot
10 20 30 40
x
a a,
Lu
50 m
r-30
�- 35 1
5 1
F— 50 1
F-55 I
0 20 40 60 80 100
Water Content (%)
Plastic Limit I 0 Liquid Limit
Natural Water Content
BORING:
Renton Village Storm System Improvement Project BH-5
HWAGEOSCIENCES INC. Renton, Washington PAGE: 2 of 2
PROJECT NO.: 2006-067 FIGURE: A-6
BORING 2006-067.GPJ 1/10/07
DRILLING COMPANY: Holocene Drilling
DRILLING METHOD: HSA, Mobile B-59
SAMPLING METHOD: SPT w/autohammer
SURFACE ELEVATION: 29 t feet
U)
g
O
03 aU .
0tt- U) Z)
0
Q
IIIIIIIIIIIIIiS
1 21
1 M]
LOCATION: See Figure 2
DATE STARTED: 12/8/2006
DATE COMPLETED: 12/8/2006
LOGGED BY: B. Thurber
m
m
w
O
Z
w
Standard Penetration Test
Lu
}
-
- a)
~
(140 lb. weight, 30" drop)
Cn
uJ
o
A Blows per foot
w
Li
uNj co
N
w
Z
�
a.
2
a
2
z o
x
x
O
o_
Of
Lu
DESCRIPTION N
U)
d :
O
0 0
10 20 30 40
50 01
12
5 inches A.C.P.
GP
Dense, olive brown grading to bluish gray, slightly silty, sandy,
GM
fine to coarse GRAVEL, moist.
STRUCTURAL FILL
SM
Loose, brownish gray, silty fine SAND with scattered fine
gravel and rootlets, moist.
X
Lens of silty, fine to coarse SAND with wood fragments at
3-3.25'.
ML
_______—LALLUVIUM1--------/
SM
Very soft, greenish gray grading to grayish brown, fine sandy
SILT, wet. With detrital organics increasing with depth from
scattered to abundant. Scattered fine gravel.
— — — — — — — — — — — — — — — — — — — — — —
`' ''
PT
Poor recovery; drove 3 inches of medium stiff, plastic SILT
I
with a 1-inch gravel clast into:
Soft, dark brown, woody PEAT, moist.
`� ,
Pushed Shelby tube 2.5 feet; only 10.5 inches of recovery:
Loose, greenish gray, clayey, fine to medium SAND, wet, with
scattered fine gravel.
3/4-inch lens of soft, greenish gray CLAY, moist.
0
At 10.33', Very soft, dark brown, fine PEAT with abundant
wood, moist. Single peice of trunk wood at 10.4 feet, 2 to 4
ML
inches thick and entire width of Shelb tube
Soft, brownish gray, plastic SILT with abundant rootlets and
fine wood fragments, moist.
SP
With 1/4-inch lens of PEAT.
SM
Loose, light gray, slightly silty, fine to medium SAND, wet.
1/8-inch lens of peat at 16.25 feet, with pebble and 2-inch lens
of dark gray silty sand.
Medium dense, olive gray, clean, fine to medium SAND, wet,
with 6-inch lens of yellow brown, silty SAND.
Loose, gray with light yellow brown, clean to slightly silty, fine
to medium SAND, wet.
— — — — — — — — — — — — — — — — — — — — — —
SP
Loose, olive brown grading to blue gray, clean, fine to medium
SAND, wet. Finely bedded with rust banding and silty at 22.5
to 22.75 feet.
Loose, dark yellow brown, clean, fine to medium SAND, wet.
Rust -banding at 25 to 25.25 feet, with tan clay pieces in a
1/4-inch layer.
S-1 1-1-2
S-2 1/12"-1
S-3 5-2-2 V-
S-4
S-5 1-2-4
S-6 1-2-3
S-7 3-5-7
S-8 0-2-3
S-9 0-2-3
5-10 0-1-3
Borehole terminated at 26.5 feet.
Ground water observed at 8 feet when auger at 25 feet.
30
For a proper understanding of the nature of subsurface conditions, this
exploration log should be read in conjunction with the text of the
geotechnical report.
NOTE: This log of subsurface conditions applies only at the specked location and on the date indicated
and therefore may not necessarily be indicative of other times and/or locations.
r— 0
F--10 I
F-15 1
F—20 1
�— 25 1
L 30
0 20 40 60 80 100
Water Content (%)
Plastic Limit 1-- 0 Liquid Limit
Natural Water Content
A
...:....:....:....:....:
.... :.... :....:....
.......................................
A� ....
....:....:....:....:....:....:.... ..
BORING:
901 Renton Village Storm System Improvement Project BH-6
HWAGEOSCIENCES INC. Renton, Washington PAGE: 1 of 1
PROJECT NO.: 2006-067 FIGURE: A-7
BORING 2006-067.GPJ 1110107
DRILLING COMPANY: Holocene Drilling LOCATION: See Figure 2
DRILLING METHOD: HSA, Mobile B-59 DATE STARTED: 12/8/2006
SAMPLING METHOD: SPT w/autohammer DATE COMPLETED: 12/8/2006
SURFACE ELEVATION: 29 t feet LOGGED BY: B. Thurber
0-
5-
10-
15-
20-
1 25 -
30 -
U
w
Li
U
W
v
a
m
Cl)
w
Z)
U s
CO
O
0
~
Z
H
❑
m
w
a
w
C
w o
x N
Z
(n
w
❑
0
U)
❑
DESCRIPTION can
coa
�
O
0
A.C.P.
GP
°
GMgs:
Brownish gray, slightly silty, sandy, fine to coarse
r5inches
EL, moist.
(FILL)
S-1 17-18-19
°,
grayish brown, fine to coarse sandy, fine to coarse//LLf\\VVlli
SMEL
moist'---------------ense,
brownish gray, silty, fine gravelly, fine to medium
GP
SAND' _moist . _______________ /
`Medium
° 3
dense, gray, slightly silty, fine to coarse sandy, fine to
S-2 6-10-8
oO
coarse GRAVEL, wet.
SP
Very loose, gray, clean, fine to medium SAND, wet. Trace
coarse sand. ALLUVIUM
S-3 0-1-2
PT
Soft, dark brown, PEAT, moist, fine grading to fibrous with
"
wood fragments.
0
Very soft, brown and dark brown, fibrous, woody PEAT, moist.
S-4 0-0-2
Abundant charcoal, and lenses of grayish brown SILT with
detrital organics, moist.
Soft, dark brown, PEAT with beds of SILT, moist. Wood
ML
fragments------------------,
S-Sa 2-5-7
SM
Stiff, brownish gray, slightly organic, fine sandy SILT, moist.
S-5b
At 13 feet, 1.5-inch lens of fine SAND.
SP
— — — — — — — — — — — — — — — — — — — — — —
SM
Loose, strong brown, slightly silty, fine to medium SAND, wet.
S-6 0-2-2
Poor recovery. i�
S-7 6-8-10
Medium dense, strong brown, silty, fine to medium SAND,
wet.
Medium dense, strong brown, clean to slightly silty, fine to
S-8 0-6-6
medium SAND, wet. Some rust banding.
SP
— — — — — — — — — — — — — — — — — — — — —
SM
Medium dense, light gray grading to dark gray, finely bedded, I S-9 2-4-8
silty fine SAND, moist, grading to fine sandy SILT with piece J
of rh.—.1
Borehole terminated at 26.5 feet.
Ground water observed at 5 feet after drilling (open hole).
For a proper understanding of the nature of subsurface conditions, this
exploration log should be read in conjunction with the text of the
geotechnical report.
NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated
and therefore may not necessarily be indicative of other times and/or locations.
M
Standard Penetration Test
(140lb. weight, 30" drop)
A Blows per foot
10 20 30 40
x
wQ
50 ❑
r— 0
J
A.
�-5
F-10 I
—15
�— 20 I
F— 25
0 20 40 60 80 100
Water Content (%)
Plastic Limit 1--0 Liquid Limit
Natural Water Content
BORING:
Renton Village Storm System Improvement Project BH-7
HWAGEOSCIENCES INC. Renton, Washington PAGE: 1 of 1
PROJECT NO.: 2006-067 FIGURE: A-g
BORING 2006-067.GPJ 1/10107 '
Appendix B
APPENDIX B
LABORATORY TEST RESULTS
APPENDIX B
' LABORATORY TEST RESULTS
Representative soil samples obtained from the boreholes were returned to the HWA laboratory
for further examination and testing. Laboratory tests were conducted on selected soil samples to
characterize relevant engineering properties of the on -site materials. The laboratory testing
program was performed in general accordance with appropriate ASTM Standards, as outlined
below.
Liquid Limit, Plastic Limit, And Plasticity Index of Soils (Atterberg Limit): Selected
samples were tested using method ASTM D 4318, multi -point method. The results are reported
on the attached Liquid Limit, Plastic Limit, and Plasticity Index reports found in Figure B-1.
Moisture Content: The moisture contents of selected soil samples were determined in general
accordance with ASTM D 2216. The results are shown at the sampled intervals on the
appropriate summary logs in Appendix A.
Particle Size Analysis of Soil: Selected samples were tested to determine the particle size
distribution of material in general accordance with ASTM D 422. The results are summarized on
the attached Grain Size Distribution reports, Figures B-2 through B-5, which also provide
information regarding the classification of the sample and the moisture content at the time of
testing.
Organic Content: Organic contents were measured on selected soil samples from borehole BH-
2 in general accordance with ASTM D 2974. The results are reported on the log for BH-2 in
Appendix A.
One Dimensional Consolidation Properties of Soil: The consolidation properties of a relatively
undisturbed Shelby tube sample from borehole BH-5 were measured in general accordance with
ASTM D 2435. Saturation was maintained by inundation of the sample throughout the test. The
sample was subjected to increasing increments of total stress, the duration of which was selected
to exceed the time required for completion of primary consolidation as defined in the Standard,
Method B. Unloading of the sample was carried out incrementally. The test results, in terms of a
void ratio (e) versus log pressure (stress) plot, are presented in Figure B-6.
2006-067 Rev Final2doc B-I HWA GEOSCIENCES INC.
60
CL
CH
.00
50
'001Z
X
40
Lu
0
z_
30
U
■
Q
•
20
Li
J
10
CL-ML
/001
ML MH
0
0
20
40 60
80
100
LIQUID LIMIT (LL)
SYMBOL
SAMPLE
DEPTH (ft)
CLASSIFICATION
% MC
LL
PL.,
PI
%Fines
•
BH-1
S-1 a
1.0 - 4.5
(CL) Grayish brown, lean CLAY
28
45
23
22
■
BH-1
S-2
5.0 - 6.5
(CH) Olive brown, fat CLAY
39
53
27
26
*
BH-2
S-10
30.0 - 31.5
(CL) Greenish gray, lean CLAY
31
35
20
15
O
BH-3
S-3
7.5 - 9.0
(CL) Light olive brown, lean CLAY
28
47
26
21
❑
BH-4
S-3
7.5 - 9.0
(CL) Light olive brown, lean CLAY
43
23
20
LIQUID LIMIT, PLASTIC LIMIT AND
Renton Village Storm System Improvement Project PLASTICITY INDEX OF SOILS
LT, I
HWAGEOSCIENCES INC. METHOD ASTM D4318
PROJECT NO.: 2006-067 FIGURE: B-1 Renton, Washington
HWAATTB 2006-067.GPJ 8/11/06
U.S. STANDARD SIEVE SIZES
3/4"
12' 6" 3" 1-1/2" i5/8" 3/8" #4 #10 #20 #40 #60 #100 #200
100
I I I I I I I I I
I I I I I I I I I I I
90
I
I
I
I
I I
I
1
I
1
I
I
I
I
I
I
I
I I
I
I
I
I
I
80
I
I
I
I I
I
I
I
I
I
I
_
I
I
I
I I
I
I
I
I
I
I
70
LLJ
I
I
I
I I
I
I
I
I
I
I
I
I
I
I
I I
I
I
I
I
I
I
} 60
I I
I
I
I
I
I
I
m
I
I
I
I I
I
I
I
I
I
�
I
I
I
I
I
I
I I
I
I
I
I
I
I
I
LLI 50
I I
I
I
I
I
I
I
I
Z
I
I
I
1
I
I
I I
I
I
I
I
I
I
LL
I
I
I
I I
I
I
I
I
I
I
I— 40
I
Z
I
I
I
I I
I
I
I
I
I
I
I
LLI
I I
I
I
I
I
U
I
I
I
30
I
I
t
ui
D_
I
I
I
I I
I
I
I
I
I
I
20
1
I
I
I
I
—I
I I
I
I
I
I
I
I
I
I
I
I
I I
I
I
I
I
I
I
I
10 I I I I I I I I I I I I
I I I I I I I I I I I I
0
100 50 10 5 1 0.5 0.1 0.05 0.01 0.005 0.001 0.0005
GRAIN SIZE IN MILLIMETERS
COBBLES
GRAVEL
SAND
SILT
CLAY
Coarse
Fine
Coarse
Medium
Fine
SYMBOL
SAMPLE
DEPTH (ft)
CLASSIFICATION
% MC
LL
PL
PI
%Cobble
%Gravel
%Sand
%Fines
•
BH-1
S-3
7.5 - 9.0
(SM) Light brown, silty SAND
25
0.0
79.1
20.9
■
BH-1
S-5
12.5 - 14.0
(ML) Light brown, sandy SILT
18
1.8
42.0
56.2
A
BH-1
S-7
17.5 - 19.0
(SM) Light yellowish brown, silty SAND
18
0.0
73.7
26.3
PARTICLE -SIZE ANALYSIS
Renton Village Storm System Improvement Project OF SOILS
Renton, Washington METHOD ASTM D422
HWAGEOSCIENCES INC.
PROJECT NO.: 20O6-OG7 FIGURE: B-2
HWAGRSZ2 2006-067.GPJ 10/27/06
IIIIIIIIIIIIIIIII1II L
IIIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIIIIII GRAVEL
RAVEL III+IIIIIIIIIIIIIII IIIIIIIIIIIIIIIIIII
IIIIIIIIIIIIiIIIIISAND IIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIIII
�IIII1IIIIIIIIIIII
'
SILT
U.S. STANDARD SIEVE SIZES
3/4"
12" 6" 3' 1-1/2" 5/8" 3/8" #4 #10 #20 #40 #60 #100 #200
100
90
80
70
60
mLLI 50
Z40
ZU 30
a20
10
iL
0 I II I 1--LI
100 50 10 5 1 0.5 0.1 0.05 0.01 0.005 0.001
0
.
0
005
GRAIN SIZE IN MILLIMETERS
SYMBOL SAMPLE DEPTH (ft) CLASSIFICATION % MC LL PL PI %Cobble %Gravel %Sand %Fines
• BH-2 S-2 5.0-6.5 (SM) Dark grayish brown, silty SAND 14 9.5 57.2 33.2
■ BH-2 S-8 20.0-21.5 (SM) Dark grayish brown, silty SAND 29 0.0 74.4 25.6
♦ BH-2 S-11 35.0-36.5 (ML) Dark olive gray, sandy SILT 21 1.6 47.5 50.8
COBB
ES
C
LAY
Coarse Fine CoarseMedium Fine
PARTICLE -SIZE ANALYSIS
Renton Village Storm System Improvement Project OF SOILS
Renton, Washington METHOD ASTM D422
WAGEOSCIENCESINC. PROJECT NO.: 2006-067 FIGURE:
B-3
HWAGRSZ2 2006-067.GPJ 10/27/06
COBB
ES
C
LAY
Coarse Fine CoarseMedium Fine
PARTICLE -SIZE ANALYSIS
Renton Village Storm System Improvement Project OF SOILS
Renton, Washington METHOD ASTM D422
WAGEOSCIENCESINC. PROJECT NO.: 2006-067 FIGURE:
B-3
HWAGRSZ2 2006-067.GPJ 10/27/06
PARTICLE -SIZE ANALYSIS
Renton Village Storm System Improvement Project OF SOILS
Renton, Washington METHOD ASTM D422
WAGEOSCIENCESINC. PROJECT NO.: 2006-067 FIGURE:
B-3
HWAGRSZ2 2006-067.GPJ 10/27/06
PARTICLE -SIZE ANALYSIS
Renton Village Storm System Improvement Project OF SOILS
Renton, Washington METHOD ASTM D422
WAGEOSCIENCESINC. PROJECT NO.: 2006-067 FIGURE:
B-3
HWAGRSZ2 2006-067.GPJ 10/27/06
U.S. STANDARD SIEVE SIZES
3/4"
12" 6' 3" 1-1/2" '5/8" 3/8" #4 #10 #20 #40 #60 #100 #200
100
I I I I I I I I I
I I I 1 I I I I I I
90 I I
I I I I I I I I I I I
I I I I I I I I I I I
80
= I I I I I I I I I I I
(D
70 I I I I I I I I I I
I I i I I I I I I I
m 60 I I I I I I I I I I I
W 50 I I I I I I I I I I I
Z I I I I I I I I I I I I
H 40 I I I I I I I I I I I
Z I I I
W I I I I I I I I I I I
U 30 I I I I I I I I I
I I I I I I I I I I I I
W I I I I I I I I I I I
20
I I I I I I I I I I I
I I I I I I I I I I I
10 I I I I I I I I I I I I
I I I I I I I I I I I 1
0
100 50 10 5 1 0.5 0.1 0.05 0.01 0.005 0.001 0.0005
GRAIN SIZE IN MILLIMETERS
COBBLES
COBBLES
GRAVEL
SAND
SILT
CLAY
SYMBOL SAMPLE DEPTH (ft) CLASSIFICATION % MC LL PL PI %Cobble %Gravel %Sand %Fines
* BH-3 S-1 2.5 - 4.0 (SM) Grayish brown, silty SAND 11 5.9 49.4 44.8
■ BH-3 S-7 17.5 - 19.0 (SM) Light olive brown, silty SAND 27 0.0 84.1 15.9
♦ BH-4 S-1 2.5 - 4.0 (SM) Dark grayish brown, silty SAND with gravel 7 34.7 47.7 17.6
PARTICLE -SIZE ANALYSIS
Renton Village Storm System Improvement Project OF SOILS
� METHOD ASTM D422
PROJECT NO.: 2006-067 FIGURE: B-4
HWAGEOSCIENCES INC. Renton, Washington
HWAGRSZ2 2006-067.GPJ 10I27I06
PARTICLE -SIZE ANALYSIS
Renton Village Storm System Improvement Project OF SOILS
� METHOD ASTM D422
PROJECT NO.: 2006-067 FIGURE: B-4
HWAGEOSCIENCES INC. Renton, Washington
HWAGRSZ2 2006-067.GPJ 10I27I06
U.S. STANDARD SIEVE SIZES
3/4"
12" 6" 3" 1-1/2" i5/8" 3/8" #4 #10 #20 #40 #60 #100 #200
100
I I I I I I I I I I I
I I I I I I I I I I I
90
I I I I I I I I I I I I
80 I I I I I I
= I I I I I I I I I I I I
C�
W 70 I I I I I I I I I I I I
I I I I I 1 I I I I I I
m 60 I I I I I I I I I I I
W 50 I I I I I I I I I I I I
ZLL
I I I I I I I I I I I I
I I I I I I I I I I I I
F— 40
Z I I I I I I I I I I I I
W I I I I I I I I I I I I
U 30 I_
I I I I I I I I I I I I
a I I I I I I I I I I I I
20
I I I I I I I I I I I I
I I I I I I I I I I I I
10 I I I I I I I I I I I I
I I I 1 1 I I I I I I I
0
100 50 10 5 1 0.5 0.1 0.05 0.01 0.005 0.001 0.0005
GRAIN SIZE IN MILLIMETERS
COBBLES
COBBLES
GRAVEL
SAND
SILT
CLAY
SYMBOL SAMPLE DEPTH (ft) CLASSIFICATION % MC LL PL PI %Cobble %Gravel %Sand %Fines
• BH-4 S-5 12.5 - 14.0 (SP-SM) Brown, poorly graded SAND with silt 21 0.0 89.6 10.4
0 BH-4 S-9b 26.1 - 26.5 (ML) Light olive brown, SILT 32 0.0 13.8 86.2
PARTICLE -SIZE ANALYSIS
Renton Village Storm System Improvement Project OF SOILS
� METHOD ASTM D422
PROJECT NO.: 2006-067 FIGURE: B-5
HWAGEOSCIENCES INC. Renton, Washington
HWAGRSZ2 2006-067.GPJ 10/27/06
PARTICLE -SIZE ANALYSIS
Renton Village Storm System Improvement Project OF SOILS
� METHOD ASTM D422
PROJECT NO.: 2006-067 FIGURE: B-5
HWAGEOSCIENCES INC. Renton, Washington
HWAGRSZ2 2006-067.GPJ 10/27/06
R, j.7 ONE DIMENSIONAL
�ii� CONSOLIDATION
HWAGEOSCIENCES INC. ASTM D 2435
Project Name: Renton Village SS
Project Number: 2006-067-21
Borehole Number: BH-5
Sample Number: S-6
Sample Depth: 16-17.5'
Soil Description: Dark Brown, Slightly Silty Peat (Pt)
Coeff. of Consol.(in2/minute)
1.0E-03 1.0E-02 1.0E-01 1.0E+00
5.0 I--r- rrnni-r- rnrnl___i-rnnnl
4.5
4.0
3.5
m
0
M
3.0
v
0
2.5
2.0
1.5
1.0
5.00
4.50
4.00
3.50
0
0
Y
3.00
0
2.50
2.00
1.50
1.00
0.100
Start
Finish
Void Ratio
4.415
2.354
Moisture Content
218.4
121.3 %
Saturation
99.0
103.1 %
Dry Density
23.1
37.2 pcf
Void Ratio vs. Stress
1.000 10.000 100.000
Stress (ksf)
FIGURE B-6
Appendix C
APPENDIX C
t AQUIFER TESTING AND ANALYSIS
APPENDIX C
AQUIFER TESTING AND ANALYSIS
Slug Tests
HWA used single -well hydraulic conductivity testing to estimate aquifer parameters. Our aquifer
testing program included rate -of -fall (falling head) and rate -of -rise (rising head) slug tests on
piezometers BH-1 and BH-4.
We used the Bouwer and Rice method to analyze the slug test results in piezometers that
displayed suitable drawdown curves. The Bouwer and Rice method can be used for "slug tests
on partially or completely penetrating wells in unconfined aquifers for a wide range of geometry
conditions" (Bouwer and Rice, 1976).
Pumping Test
A short-term pumping test was conducted at BH-4 using a two-inch diameter electrical
submersible pump. Response to pumping at the pumping well, and recovery after pumping was
stopped, were measured using data logging pressure transducers. We used the Theis and Jacob
method to analyze the recovery test results (Driscoll, 1986).
Data from some tests was not analyzed due to interference from the sand filter pack, or other
interference. Table 2 summarizes the slug and pumping test results.
HWA analyzed the results of the slug and pumping tests using the above listed methods with the
Aquifer Test for Windows Version 2.55 software (Rohrich, 1996). The pumping test data,
drawdown curves, and calculations are included at the end of Appendix C.
Table 2
' Pumping Test Analysis Results
Well
Test
Estimated
Comments
ID
K (ft/min)
BH-1
Falling head
4.16xl0-5
BH-1
Rising head
4.57xl0-5
BH-4
Falling head (two
NA
Very rapid response, possible
tests)
well filter pack influence
BH-4
Rising head (test 1)
1.38x10-3
BH-4
Rising head (test 2)
1.14x10-3
BH-4
Pumping Recovery
6.79x10-3
NA - not analyzed
' 2006-067 Rev Final2.doc
HWA GEOSCIENCES INC.
' Dewatering Estimates
HWA utilized the Universal Well Formula, a derivative of Darcy's Law to estimate the amount
of flow from wells dewatering a length of excavated trench (Powers, 1992), where:
__ 7rK(H2 —h2 +2 xK H2 —h2
Q In R. 2L
rs
and
' Q = Rate of discharge to lower water table to target elevation (ft3/min)
K = Hydraulic conductivity (ft/min)
' H = Height of static potentiometric surface above base of aquifer (aquifer thickness)
h = Height of controlled potentiometric surface above base of aquifer
Ro= Radius of influence (cylindrical area)
L = Radius of influence (linear area) or distance to line source
rs = Radius of trench (5 feet)
x = Length of trench segment dewatered
Aquifer thickness H - Existing well log data in the project area suggest that the total aquifer
' thickness is approximately 20 feet.
Height of controlled potentiometric surface above base of aquifer (h) - This value was estimated
based on measured ground water levels, and estimated trench invert depths with an added four
feet of drawdown.
Radius of influence (Ro) - Radius of influence was estimated based on Suchart's formula:
R. = 300(H — h)�K_
with Ro, H and h in feet, and K in cm/sec.
The above -listed principal dewatering parameters serve as the basis for estimating dewatering
flows. Extreme variability (spatially and temporally) throughout the site of these dewatering
parameters requires simplifying assumptions based on the available data in order to develop
estimates of dewatering volumes. This method assumes flow to wells along the trench. Trench
' dewatering estimates are summarized in Table 3.
' 2006-067 Rev Final2.doc
HWA GEOSCIENCES INC.
Table 3
Dewatering Flow Estimates
(Gallons per minute per 100 foot of trench)
Well
4.3.4.1.1.1.1.1 Assumptions
Trench
Depth to
Open
K
Invert
Water
Trench
(ft/min)
Depth
(feet)
(9pm/100ft)
BH-1
4.4xl0-5
10
5
1
BH-4
3.1x10-3
10
6
12
1 - Based on average of different tests performed
2 - Dewatering depth four feet below trench invert
REFERENCES
Driscoll, F., Groundwater and Wells, Johnson Division, St. Paul, Minnesota, 1986.
Powers, J. Patrick, Construction Dewatering, New Methods and Applications, John Wiley
and Sons, Inc., New York, 1992.
2006-067 Rev Final2.doc HWA GEOSCIENCES INC.