HomeMy WebLinkAboutWWP273473 (12)FINAL GEOTECHNICAL REPORT
Renton-Stonegate 11
Sewer System Improvements Project
Renton, Washington
HWA Project No. 2007-080-21 Task 1200
Prepared for
Roth Hill Engineering Partners LLC
November 7, 2008
=1
HWAGEOSCIENCES INC.
• Ceorechnicnl Engineering
• Hyd rog*enl og y
• Geocnvironntoraal Services
• Inspection & Teting
e HWA GEOSCIE CES INC.
® 'eoh'lchnical & Pavement r.rrgrnrrerinv • lgydro.ticofa.i�v lnspcoio.,! & Testing
November 7, 2008
HWA Project No. 2007-080-21 "r1200
Roth Hill Engineering Partners LLC
2600 1161h Avenue NE,, Suite 100
Bellevue, Washington 98004
Attention: Erik Waligorski, P.E.
Subject: FINAL GEOTECHNI CAL REPORT
RENTON-STONEGATE II
SEWER SYSTEM IMPROVEiNIENT,S PROJECT
Renton, Washington
Dear Mr. Waligorski:
This letter transnuts our final geotechnical.report for the Renton-Stonegate II Sewer System
Improvements Project in Renton, Washington. Weappreciate the opportunity to provide
geotechnical services for this project. Should you have any questions or comments concerning
our enclosed report, or if we may be of further service, please call.
Sincerely,
HWA GEOSCTENCES INC.
Steven E. Greene, L.E.G.
Vice President
SEG:EOA:seg.
Erik O. Andersen, P.E.
Geotechnical, Group Manager
19730 - 641h Avenue W.
Suitc 200
►:ynnwood, WA.981136,5957
Tel: 425J74.0106
Fax: 425.774.127.t,!
ivwiv.hwageo.com_
TABLE OF CONTENTS
Pa e
1.0 INTRODUCTION...................................................................................................
1.1 GENERAL......................................................................................................1
I
1.2 PROJECT DESCRIPTION.................................................................................
1
'
1.3 SCOPE OF SERVICES AND AUTHORIZATION...................................................
2.0 FIELD EXPLORATION AND LABORATORY TESTING .................................
2
2
2.1 FIELD EXPLORATION....................................................................................
2
'
2.2 LABORATORY TESTING................................................................................
3.0 SITE CONDITIONS...............................................................................................
3
3
3.1 SURFACE CONDITIONS..................................................................................
3
3.2 SITE GEOLOGY.............................................................................................
4
3.3 SUBSURFACE CONDITIONS...........................................................................
4
3.3.1 NE Field Avenue (BH-IA through BH-4B).................................4
3.3.2 NE 20th Street(BH-5)..................................................................5
3.3.3 Lyons Avenue NE(BH-6)............................................................6
3.3.4 147th Avenue SE (BH-7).............................................................
7
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3.3.5 148th Avenue SE (BH-8).............................................................
8
3.3.6 Stone ate-Summerwind Connector BH-9 & BH-10
9
'
3.3.7 NE 261" Street Culvert Under -crossing (BH-13 & BH-14) ........
3.3.8 Proposed Stonegate II Lift Station (BH-I I & BH-12)...............12
10
3.3.9 Summary of Soil Conditions......................................................13
'
4.0 RECOMMENDATIONS......................................................................................15
4.1 GENERAL......................................................................................................
15
4.2 STONEGATE 11 LIFT STATION.......................................................................
15
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4.2.1 Temporary Shoring......................................................................15
4.2.2 Ground Water Control / Dewatering............................................16
4.2.3 Lift Station Excavation................................................................17
'
4.2.4 Buoyancy.....................................................................................17
4.3 PIPE BURSTING.............................................................................................
17
4.4 HORIZONTAL DIRECTIONAL DRILLING.........................................................
20
'
4.5 OPEN CUT TRENCHING.................................................................................
4.5.1 Soil Excavation Characteristics...................................................
21
21
4.5.2 Sloped Open -Cut Excavations.....................................................
21
4.3.1 Shored Excavations....................................................................
22
4.3.2 Ground Water and Construction Dewatering .............................23
4.3.3 Pipeline and Manhole Settlement...............................................23
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4.3.4 Pipeline Support and Bedding....................................................24
4.3.5 Trench Backfill Materials and Compaction...............................24
4.3.6 Pipeline and Buried Structure Design Considerations ...............26
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HWA Project No. 2007-080-21 T1200
4.3.7 Jacking and Insertion Pits...........................................................27
4.4 SEISMIC CONSIDERATIONS.........................................................................27
4.5 WET WEATHER EARTHWORK.....................................................................28
4.6 DRAINAGE AND EROSION CONSIDERATIONS .............................................. 29
5.0 CONDITIONS AND LIMITATIONS..................................................................29
6.0 REFERENCES...................................................................................................... 31
LIST OF FIGURES
Figure 1 Project Site & Vicinity Map
Figure 2 Project Alignment and Exploration Locations
Figures 3 - 5 Site and Exploration Plan Maps
Figure 6 Design Earth Pressures for Temporary Braced Shoring
Figure 7 Parameters for Calculating Uplift Resistance
APPENDIX A — EXPLORATION LOGS
Figure A-1. Legend of Terms and Symbols
Figures A-2 through A-19. Logs of Exploratory Borings (BH-1 — BH-14)
APPENDIX B — LABORATORY TESTING
Figures B-1 through B-8. Particle -Size Analysis of Soils
Figure B-9. Atterberg Limits
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' FINAL GEOTECHNICAL REPORT
RENTON-STONEGATE II
SEWER SYSTEM IMPROVEMENTS 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 Roth Hill and the City of Renton Public Works. Currently, the
existing residential developments known as Summerwind and Stonegate are served by separate
gravity collection systems, lift stations, and force main conveyance systems. The purpose of this
project is to combine the flows and utilize a single force main system. This will be accomplished
by converting the existing Summerwind lift station into a manhole and installing new gravity
sewer between the converted wet well and the existing Stonegate sewer manhole located in NE
24`h Court. The combined Summerwind and Stonegate flows will then be conveyed by the
'
existing Stonegate gravity system to a new lift station located adjacent to the existing Stonegate
lift station at the northwest corner of NE 26`h Street and 1481h Avenue SE. It is assumed that the
existing Stonegate gravity sewer has sufficient capacity to handle the increased flow.
From the new Stonegate lift station, combined flow will be conveyed via force main uphill to the
west, and southwest along NE 26th Street and Lyons Avenue NE, NE 22nd Court, along an
easement between the two developments connecting to NE 20`h Street, and the gravity system on
NE Field Avenue. The existing NE Field Avenue system is constructed of mostly 8-inch
diameter PVC and the pipe will be replaced/upsized to handle the increased flow.
'
The location of the project and project alignment is shown on the Project Site & Vicinity Map,
and the Project Alignment and Exploration Locations on Figures 1 and 2, respectively. The
general layout of the roadway and the location of the existing pipeline system are shown on
Figures 3 through 5.
'
The purpose of this geotechnical investigation was to plan, conduct and present the results of our
geotechnical explorations and provide geotechnical recommendations for the design and
construction of the planned improvements.
1.2 PROJECT DESCRH'TION
' The project will include design and construction of gravity connector lines between the existing
Summerwind and Stonegate systems, using horizontal directional drilling methods; a new Lift
Station north of the existing Stonegate lift station that will handle the combined flows; a new
' force main to convey sewage up to NE Field Avenue; and upsizing of the existing gravity
November 7, 2008
HWA Project No. 2007-080-21 T1200
conveyance along NE Field Avenue. The conveyance alignment is typically situated along a
series of two-lane residential streets. Open excavation for the new force main will have some
impact on local traffic, and will require surface restoration. At the culvert crossing along
NE 26`h Street, open trench construction and horizontal directional drilling(HDD) are under
consideration. Design and construction of the new lift station will require shored excavations
and dewatering. Upsizing of the existing gravity conveyance system along NE Field Avenue is
expected to employ trenchless technologies (such as pipe -bursting) to minimize potential damage
to the existing roadway.
1.3 SCOPE OF SERVICES AND AUTHORIZATION
The purpose of the geotechnical investigation work tasks was to characterize the subsurface
conditions along the project alignment so that recommendations for design and construction of
the proposed sanitary sewer and lift station replacement improvements could be made in support
of the Roth Hill design team. Our work tasks were performed in general accordance with the
scope of work, as described in our Sub -consultant Agreement executed on March 7th, 2008;
supplemented in August of 2008. Our scope of work did not include environmental assessment
of the project alignments.
2.0 FIELD EXPLORATION AND LABORATORY TESTING
2.1 FIELD EXPLORATION
Our field investigation consisted of 18 borings, designated as BH-IA and 113 through 4A and 413
(8 borings), and 13H-5 through BH-14 (8 borings), to explore the subsurface conditions along the
proposed project alignment, both ends of the Stonegate — Summerwind connection, and at the
new lift station location. The borings were conducted at the locations proposed previously in our
Exploration Plan. The approximate boring locations are shown on the Site and Exploration Plan
drawings, Figures 3 through 5.
The borings were conducted on May 7`h, May .81h, and June 4th, 2008, by Gregory Drilling of
Redmond, Washington, and Davies Drilling of Snohomish, Washington. The borings were
advanced using truck and a track -mounted drill rigs, respectively, under the direction of an HWA
geologist. Supplemental borings for the culvert crossing along NE 261h Street were conducted on
September I I'h, 2008, by Holocene Drilling of Graham, Washington, using a truck -mounted drill
rig. The borings were advanced to depths ranging between approximately 5 and 41.5 feet below
the ground surface. Standard Penetration Tests (SPTs) were performed at 5 and/or 2'/2-foot
intervals in each of the borings in general accordance with ASTM D-1586. The SPT consists of
driving a 2-inch O.D. split -spoon sampler a distance of 18 inches into the bottom of the borehole
with a 140-pound hammer falling 30 inches. The number of blows required to drive the sampler
each of three 6-inch increments was recorded, and the number of blows required to cause the last
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HWA Project No. 2007-080-21 T1200
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12 inches of penetration was termed the SPT (N-value). This value is an indicator of the relative
in situ density or consistency of the soils.
Piezometers for measuring ground water levels were installed in borings 131-1-5, 131-1-7, BH-11
and BH-13. They consisted of slotted, 2-inch PVC, standpipes installed to near the bottom of the
borings. The annulus around the slotted portions of the pipes was backfilled with No. 10-20
Colorado Sand, and a cement slurry seal and locking monument casing were placed at the ground
surface to prevent inflow of surface water. The piezometer installations are shown schematically
illustrated on the boring logs, as appropriate. These piezometers are the property of the City of
Renton. During or after construction of this project, the piezometers will need to be abandoned
in accordance with Ecology requirements. HWA can assist with piezometer abandonment, if
Irequested,
but the costs of future abandonment are not included within our scope of work.
HWA personnel recorded pertinent information including, blow counts, soil sample depths,
stratigraphy, soil engineering characteristics, and ground water occurrence as the explorations
were advanced. Soils were classified in general accordance with the classification system
described in Figure A-1, which also provides a key to the exploration log symbols. The
'
summary logs are presented in Figures A-2 and A-19. The stratigraphic contacts shown on the
individual logs represent the approximate boundaries between soil types. The actual transitions
may be more gradual.
t2.2
LABORATORY TESTING
Laboratory tests were conducted on selected samples obtained from the explorations to
characterize engineering and index properties of the project soils. Laboratory tests included
determination of in -situ moisture content, grain size distribution, and Atterberg Limits. The tests
were conducted in general accordance with appropriate American Society of Testing and
Materials (ASTM) standards. The results are discussed in further detail and are presented in
Appendix B, or are displayed on the exploration logs in Appendix A, as appropriate.
3.0 SITE CONDITIONS
1
3.1
SURFACE CONDITIONS
The project is situated along a sloping glacial upland area south of May Creek in northeastern
Renton, Washington. The project is located on relatively quiet residential streets having two
paved traffic lanes and typically room for parked vehicles on at least one or both sides. The site
for the planned new Stonegate Il lift station is north of the existing Stonegate lift station on an
alluvial plain south of May Creek.
1 Stonegate Il Final Geotech Report.doc 3 HWA GeoSciences Inc.
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HWA Project No. 2007-080-21 T1200
3.2 SITE GEOLOGY
Geologic information for the project area was obtained from a map titled Composite Geologic
Map of King County, Washington (D.B. Booth et al, 2006) published by the U.S. Geological
Survey. Near -surface deposits in the project vicinity are mapped as Vashon glacial till. Near the
banks of May Creek, glacial soils have been reworked or eroded and/or replaced with alluvial
soils.
Vashon till generally consists of a very compact unsorted mixture of clay, silt, sand, and gravel,
deposited directly by the Puget Lobe of the Cordilleran Ice Sheet. It was consolidated by several
thousand feet of glacial ice and is, therefore, very dense. Locally, the Vashon till may be
overlain by a layer of recessional outwash, consisting of loose to medium dense sand and gravel
that was deposited by glacial meltwater emanating from the receding glacial front. Additionally,
the Vashon till may be underlain by advance outwash, consisting of dense gravelly sand.
Advance outwash was deposited by meltwater flowing from the advancing glacial front and,
consequently, was over -ridden and consolidated by the weight of the glacial ice.
May Creek alluvial soils typically consist of loose to medium dense sands, gravels and silts
derived from existing glacial soils or colluvium. Colluvium is slope -wash material originating
on and transported down steep slopes by local weathering processes (i.e. runoff and mass
wasting).
3.3 SUBSURFACE CONDITIONS
Our explorations encountered glacial till in most locations, which generally agrees with the
geologic map description. Man -modified fill materials were encountered above the existing
sewer trench on Field Avenue, and along the proposed alignment beneath roadways. Recent
alluvium, recessional glacial outwash, recessional glacial lacustrine, glacial till and advance
glacial outwash soils were encountered at locations near May Creek, such as the culvert crossing
at NE 26`h Street and the area proposed to accommodate the new Stonegate II lift Station.
3.3.1 NE Field Avenue (BH-1A through BH-4B)
Exploration borings were conducted in pairs, located within (borings designated as A) and
outside (borings designated as B) the existing sewer trench limits, so that the engineering
properties of the existing trench backfill and the adjacent local native soils could be
characterized. In general, the native subsoil along the NE Field Avenue alignment
predominately consists of very dense glacial till soils, locally overlain by native fills of varying
thickness. The existing sewer trenches appear to have been backfilled with native trench spoil
materials comprised predominately of loose to medium dense silty sand and gravelly silt, which
was likely derived from on -site trench excavations in glacial till. No ground water seepage was
observed while conducting these borings along NE Field Avenue.
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_November 7, 2008 _
HWA Project No. 2007-080-21 T1200
The approximate locations of these borings are shown on Figures 3A through 3C.
The soil units encountered in our borings, or anticipated outside of the existing sewer alignment
along NE Field Avenue, are described below, with materials interpreted as being youngest in
origin and nearest the surface described first.
t•
ACP Surfacing — ACP (asphaltic concrete pavement) was encountered at the surface at bore
holes BH-la through 4b, where it was typically 0.4 feet (5 inches) thick over the sewer trench
'
and 0.2 feet (2'/z inches) thick about 5 feet towards the curb, respectively.
• Road Base — Immediately beneath the existing ACPsurfacing, roadway fill consisting of
Iplaced
medium dense to dense, gray, sandy gravel was encountered. Apparently, this material was
as base prior to paving NE Field Avenue. The road base aggregate ranged from 0.6 to
0.8 feet (7 to 10 inches) in thickness.
• Fill — Immediately beneath the existing road base, in BH-113, 213, 313 and 413 (located outside
the sewer trench limits), fill consisting of medium dense to very dense, brown to olive gray,
silty sand with gravel was encountered. This material was likely placed during construction
of NE Field Avenue. The fill ranged from 1.0 to 4.0 feet in thickness.
• Trench Backfill — Existing sewer trench backfill, consisting of trench spoils comprised
predominately of medium dense to loose, olive brown to gray, silty sand with gravel to
gravelly silt with sand, was encountered in borings BH-IA, 2A, 3A, and 4A within the
existing sewer trench limits. The trench backfill explored ranged from 5 to 6 feet in
t
thickness. The trench backfill material was not fully penetrated by our borings, as all four of
the borings were terminated at least 1-foot above the existing sewer pipe crown to avoid
damaging the pipe. Evaluation of natural soil moisture content and SPT data for this material
indicates that is was probably placed loosely and wet of what is optimum for adequate
compaction. These soils will, accordingly, be relatively easy to displace during pipe-
bursting operations.
• Vashon Till — In general, native glacial till, consisting of dense to very dense, gray, silty
sand with gravel to silty gravel with sand, was encountered in the borings outside of the
trench line (all B borings), and constitutes the local native soil unit that will be encountered
during construction.
'
3.3.2 NE 20th Street (BH-5)
This location is along the western end of the proposed force system alignment before it ties in to
the existing gravity system situated along NE Field Avenue, and may locally accommodate a
receiving pit should the new force main be installed by directional drilling methods. The
approximate location of this boring is shown on Figure 3D. Therefore, our exploration boring
'
(BH-5) was conducted with closely spaced (2.5 foot) sampling intervals in the upper
Stonegate II Final Geotech Report.doc 5 HWA GeoSciences Inc.
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November 7, 2008
HWA Project No. 2007-080-21 T1200
10-11.5 feet, and with more widely spaced (5 foot) intervals once the boring was well into very
dense native soils, to characterize the engineering properties of local fill and native soils, and
attempt to detect local ground water seepage. In general, the NE 20th Street location is underlain
by native subsoil, predominately consisting of very dense glacial till soils, locally overlain by
medium dense weathered till and native fills of varying thickness. 131-1-5 was conducted to a
final depth of 31 feet below the existing ground surface. No ground water seepage was observed
while conducting boring 13H-5 on NE 201h Street.
The soil units encountered in this boring are described below, with materials interpreted as being
youngest in origin and nearest the surface described first.
• ACP Surfacing — ACP (asphaltic concrete pavement) was encountered at the surface at
131-1-5, where it was about 0.2 feet (2'/2 inches).
• Road Base — Immediately beneath the existing ACP surfacing, roadway fill consisting of
medium dense, gray, sandy gravel was encountered. Apparently, this material was placed
prior to paving NE 20`h Street. The road base aggregate at this location was about 0.3 feet
(3'/2 inches) in thickness.
Weathered Till — Immediately beneath the existing road base in 13H-5, weathered till
consisting of medium dense, olive gray, silty fine to medium sand with gravel was
encountered. This material represents native glacial till soil that was subject to weathering
prior to the construction of NE 201h Street. The weathered till at the location of 131-1-5 was
about 5'/2 feet in thickness. This soil will provide adequate bearing for a sewer pipeline.
Vashon Till — In general, native glacial till, consisting of dense to very dense, gray, silty
sand with gravel to silty gravel with sand, was encountered in the 131-1-5 beneath the layer of
weathered till, and constitutes the deepest local native soil unit encountered during drilling at
this location, where it was in excess of 24 feet thick and not fully penetrated. This soil will
provide excellent bearing for a sewer pipeline.
3.3.3 Lyons Avenue NE (BH-6)
This location is down slope of boring 13H-5, situated at the southern terminus of Lyons
Avenue NE. The approximate location of this boring is shown on Figure 3D. At this location,
131-1-6 was conducted with closely spaced (2.5 foot) sampling intervals in the upper 6.5 feet, and
more widely spaced (5 foot) intervals once the boring encountered very dense native soil to
characterize the engineering properties of the local subsoils and attempt to detect local ground
water seepage. In general, this NE Lyons Avenue location is underlain by native subsoil,
predominately consisting of very dense glacial till soils that are locally overlain by medium
dense, weathered till and native fills of varying thickness. 131-1-6 was conducted to a final depth
of 20'/2 feet below the existing ground surface. No ground water seepage was observed while
conducting boring 131-1-6 on NE Lyons Avenue.
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HWA Project No. 2007-080-21 T1200
iThe
soil units encountered in this boring are described below, with materials interpreted as being
youngest in origin and nearest the surface described first.
• ACP Surfacing — ACP (asphaltic concrete pavement) was encountered at the surface at
131-1-6, where it was 0.33 feet (4 inches).
t•
Road Base — Immediately beneath the existing ACP surfacing, roadway fill consisting of
very dense, gray, gravel with sand was encountered. Apparently, this material was placed
prior to paving NE Lyons Avenue. The road base aggregate at this location was about
'
0.66 feet (8 inches) in thickness.
1
• Fill — Immediately beneath the existing road base in 13H-6, fill consisting of dense, olive gray
to brown, gravelly, silty sand was encountered. Apparently, this material was placed during
construction of NE Lyons Avenue. The fill was about 3.0 feet thick at this location.
• Weathered Till — Immediately beneath the existing road base in 131-1-6, weathered till
consisting of dense, olive gray, silty, fine to medium sand with gravel was encountered. This
material represents native glacial till soil that was subject to weathering prior to the
construction of NE Lyons Avenue. The weathered till at the location of 131-1-6 was about
3.0 feet in thickness. This soil will provide adequate bearing for a sewer pipeline.
Vashon Till — In general, native glacial till, consisting of dense to very dense, gray, silty
sand with gravel to silty gravel with sand, was encountered in the 131-1-6 beneath the layer of
weathered till, and constitutes the deepest local native soil unit encountered during drilling at
this location, where it was in excess of 13.5 feet thick and not fully penetrated. This soil will
provide excellent bearing for a sewer pipeline.
1
3.3.4 147th SE
Avenue (BH-7)
This location is along the originally proposed force main alignment east of where the force main
would have to cross an unnamed creek in the local valley bottom, situated near the southern
terminus of 147`h Avenue NE. The approximate location of this boring is shown on Figure 3E.
At this location, 131-1-7 was conducted with closely spaced (2.5 foot) sampling intervals in the
upper 15-16.5 feet, and more widely spaced (5 foot) intervals once the boring encountered very
dense native soil, to characterize the engineering properties of the local subsoils and attempt to
detect local ground water seepage. In general, the NE Lyons Avenue location is underlain by
native subsoil, predominately consisting of very dense glacial till soils that locally are overlain
by medium dense weathered till and native fills of varying thickness. 131-1-7 was conducted to a
final depth of 21.5 feet below the existing ground surface. Ground water seepage was observed
at an approximate depth of 10 feet below the existing ground surface while conducting boring
131-1-7 on 147`h Avenue NE. 131-1-7 was completed as a standpipe piezometer to allow for ground
'
water level monitoring during the upcoming wet weather season.
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HWA Project No. 2007-080-21 T1200
The soil units encountered in this boring are described below, with materials interpreted as being
youngest in origin and nearest the surface described first.
• Road Base — Immediately at the ground surface, roadway fill consisting of medium dense,
olive gray, fine, sandy gravel was encountered. This material was placed as the trafficking
course along this road. At this location, the road base was about 0.75 feet (9 inches) thick.
Alluvium — Immediately beneath the existing road base in BH-7, disturbed to medium
dense/stiff alluvial soil consisting of olive brown to gray, clean to silty, fine sand with some
scattered fine gravel to silt with sand was encountered. This material appears to represent
native alluvial soil deposited by local fluvial processes. The alluvium at the location of BH-7
was about 11.3 feet in thickness. This soil will provide adequate bearing for a sewer
pipeline.
Glacial Outwash — Beneath the alluvium, a layer of native glacial outwash, consisting of
dense, olive brown to gray, silt with sand and gravel to gravelly silty sand was encountered in
BH-7, and constitutes the deepest local native soil unit encountered during drilling at this
location, where it was in excess of 9.0 feet thick and not fully penetrated.
3.3.5 148th Avenue SE (BH-8)
This location is along the originally proposed force main alignment east of where the force main
would have turned west to traverse down slope toward the valley incised by the unnamed creek
along the west shoulder of 148th Avenue NE. The approximate location of this boring is shown
on Figure 3F. At this location, BH-8 was conducted with closely spaced (2.5 foot) sampling
intervals in the upper 15-16.5 feet, and more widely spaced (5 foot) intervals once the boring
encountered very dense native soil, to characterize the engineering properties of the local
subsoils and attempt to detect local ground water seepage. In general, the 146th Avenue NE
location is underlain by native subsoil, predominately consisting of very dense glacial till soils
that locally are overlain by medium dense weathered till and native fills of varying thickness.
BH-8 was conducted to a final depth of 31.5 feet below the existing ground surface. Ground
water seepage was observed while conducting boring BH-8 on 148th Avenue NE. Perched
ground water seepage was observed at depth of 23 to 28 feet. Seepage appeared to be carried by
a relatively clean sand seam within the till.
The soil units encountered in this boring are described below, with materials interpreted as being
youngest in origin and nearest the surface described first.
• ACP Surfacing— ACP (asphaltic concrete pavement) was encountered at the surface at
BH-8, where it was about 0.66 feet (8 inches).
Road Fill — Immediately beneath the existing ACP surfacing, roadway fill consisting of
loose, brown, silty sand with gravel was encountered. Apparently, this material was placed
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HWA Project No. 2007-080-21 T1200
prior to paving 148th Avenue NE. The road fill at this location was about 1.33 feet
(16 inches) thick.
• Weathered Till — Immediately beneath the existing road fill in BH-8, weathered till
consisting of medium dense, light brown, silty fine sand with gravel was encountered. This
material represents native glacial till soil that was subject to weathering prior to the
construction of 148th Avenue NE. The weathered till at the location of BH-8 was about
3.0 feet thick.
' • Vashon Till — In general, native glacial till, consisting of medium dense to very dense, olive
brown to gray, silty sand with gravel, was encountered in the BH-8 beneath the layer of
weathered till, and constitutes the deepest local native soil unit encountered during drilling at
this location, where it was in excess of 25.25 feet thick and not fully penetrated. Locally, the
till contains clean sand seams which, if saturated, can drain when encountered in excavations.
3.3.6 Stonegate-Summerwind Connector (13H-9 & BH-10)
These borings were conducted to explore the subsurface conditions along the route proposed to
connect the wet well at the existing Summerwind lift station (131-1-9) with the Stonegate gravity
sewer system in NE 24th Court (131-1-10) as shown on Figure 4. At the wet well location, BH-9
was conducted with closely spaced (2.5 foot) sampling intervals in the upper 10-11.5 feet, and
more widely spaced (5 foot) intervals once the boring encountered very dense native soil, to
characterize the engineering properties of the local subsoils and attempt to detect local ground
water seepage. In general, BH-9 encountered native subsoil below a depth of approximately
13.5 feet, predominately consisting of very dense glacial till soils that locally are overlain by fill
placed during the construction of the detention pond, consisting of medium dense, silty sands of
1
probable local origin. BH-9 was drilled to a depth of approximately 31 feet below the existing
ground surface. Minor perched ground water seepage was observed above the contact between
the fill and glacial till while conducting boring BH-9. BH-9 was completed as a standpipe
piezometer to allow for ground water level monitoring during the upcoming wet weather season.
BH-10 was conducted adjacent to the existing manhole situated in NE 24th Court, where the
connection with the existing Stonegate gravity system will be made. At this location, the upper
7 feet was explored using a Vactor truck in order to avoid utility damage. Below 7 feet, closely
spaced sampling, consisting of 2.5 foot intervals to a final depth 20.5 feet, was performed. In
general, BH-10 encountered native subsoil below a depth of approximately 12.5 feet,
predominately consisting of very dense glacial till soils that locally are overlain by fill, placed
during the installation of the manhole and roadway, consisting of medium dense silty sand to
sandy silt of probable local origin. No ground water seepage was observed well conducting
BH-10 at NE 24th Court.
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The soil units encountered in these borings are described below, with materials interpreted as
being youngest in origin and nearest the surface described first.
• ACP Surfacing — ACP (asphaltic concrete pavement) was encountered at the surface at t
BH-10, where it was 0.25 feet (3 inches) thick and underlain by additional 0.25 feet
(3 inches) of well compacted crushed rock base.
• Pond Fill — At the surface in BH-9, fill consisting of medium dense, gray to olive brown,
silty sand that contained wood pieces and minor amounts of organic debris was encountered. '
Apparently, this material was placed during construction of the Summerwind detention pond
adjacent to the existing lift station. The fill was about 13.5 feet thick at this location.
Construction Fill — Immediately beneath the existing road base in BH-10, construction fill
r
consisting of loose to medium dense, gray brown mottled, silty sand to sandy silt with gravel
and some cobbles was encountered. The lowermost 2.5 feet of this fill appeared to consist of
gravel placed as bedding material beneath the manhole structure. This material represents
backfill placed around the manhole. The construction fill at location of BH-10 was about
12.0 feet thick.
Vashon Till — In general, native glacial till, consisting of dense to very dense, gray, silty
sand with gravel to silty gravel with sand, was encountered in both BH-9 and BH-10, beneath
the local layers of fill, and constitutes the deepest local native soil unit encountered during
drilling at these locations, where it was in excess of 11.5 and 17 feet thick, respectively, and
not fully penetrated. This soil will provide excellent bearing for a connecting pipeline.
Piping may be installed using open cut or directional drilling methods. If directional drilling
is preferred, we recommend additional exploration along the route in an attempt to assess the
potential presence of boulders. Alternatively, open -cut methods, if practical in terms of
design invert elevation, should work reasonably well.
3.3.7 NE 26`h Street Culvert Under -crossing (BH-13 & BH-14)
These borings were conducted to explore the subsurface conditions along the route of the new
force main proposed to connect the new Stoneg ate II lift station with the existing Summerwind
gravity sewer system at NE 20`" Street, as shown on Figure 5C. At this location along NE 26th
Street, the planned force main must pass beneath a culvert that crosses the road conveying stream
flow from an unnamed creek to the wetlands associated with May Creek. Borings BH-13 and '
BH-14 were conducted at the downstream and to the east, and the downstream and to the west
of, the culvert, respectively. Both Borings were conducted to final depths of 31.5 feet, with
closely spaced sampling (2.5 foot intervals) in the upper 15-25 feet, and more widely spaced
(5 foot) intervals once the borings encountered medium dense native glacial soils, to characterize
the engineering properties of the local subsoils and attempt to detect local ground water seepage.
In general, BH-13 encountered native subsoil below a depth of approximately 7.5 feet, I
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predominately consisting of medium dense alluvial silty sand that locally is overlain by imported
fill, placed during the construction of the road and culvert, consisting of medium dense, gravelly
sand to sandy gravel. BH-14 encountered native subsoil below a depth of approximately 5 feet,
predominately consisting of medium dense alluvial silty sand that locally is overlain by imported
fill, placed during the construction of the road and culvert, consisting of medium dense gravelly
sand to sandy gravel. Ground water seepage was observed within the alluvial soils in both
borings at an approximate depth of 15 feet below the existing ground surface. BH-13 was
completed as a standpipe piezometer to allow for ground water level monitoring during the
upcoming wet weather season.
The soil units encountered in these borings are described below, with materials interpreted as
being youngest in origin and nearest the surface described first.
• ACP Surfacing — ACP (asphaltic concrete pavement) was encountered at the surface at
BH-13 and BH-14, where it was 0.25 to 0.33feet (3-4 inches) thick and underlain by an
additional 1.25 to 3.2 feet (15-38 inches) of compacted sandy gravel base. Beneath the
gravel base at both locations, a 6 inch layer of recycled asphaltic pavement (RAP) was
encountered that was probably placed as backfill during installation of the existing culvert.
Alluvium — Immediately beneath the layer of RAP in both borings, a layer of alluvial soil
consisting of medium dense, light brown, silty fine sand with some scattered fine gravel was
encountered. Locally, the deposit contains thin interbefis of stiff silt. This material appears
to represent native alluvial soil deposited by local fluvial processes. The thickness of
alluvium at the locations of BH-13 and 14 was about 26 and 24.5 feet, respectively.
Typically, this soil is suitable as foundation of non -critical, lightly loaded, structures, due to
low strength, increased settlement potential, and susceptibility to liquefaction. However, we
expect these hazards will have less potential impact on a forcemain. The piping may be
installed using open -cut or directional drilling methods. Dewatering may be required in
either case, depending upon the relationship of planned pipe invert elevation and local
ground water levels to limit incursion into trenches or jacking pits.
Recessional Lacustrine — Beneath the recessional outwash sand and gravel layer in BH-11,
a layer of stiff clayey sand to sandy clay was encountered at an approximate depth of 30 feet
and was in excess of 16.5 feet thick. In BH-12, recessional lacustrine material was
encountered, between two layers of recessional outwash, at a depth of 22 feet and was 8 feet
thick (i.e. between 22 and 30 feet BGS). This material appears to represent native fine
grained glacial lacustrine deposits that formed within lakes created by temporary dams within
or marginal to the outwash channel.
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3.3.8 Proposed Stonegate II Lift Station (13H-11 & BH-12)
,
Two borings were conducted to explore the subsurface conditions at the location proposed for
the new Stonegate II Lift Station. The new lift station is planned to be constructed north of the
existing lift station located near the corner of NE 26�h Street and 148t' Avenue NE, as shown on
,
Figure 5B. According to Roth Hill, the invert of the wetwell/overflow structure will be about
26.5 feet below existing grade. At both locations, the borings were conducted with closely
spaced (2.5 foot) sampling intervals in the upper 10-11.5 feet, and more widely spaced (5 foot)
intervals once the boring encountered medium dense native soil, to characterize the engineering
properties of the local subsoils and attempt to detect local ground water seepage. In general,
both borings encountered a thin layer of alluvial soils overlying recessional outwash and
recessional lacustrine soils. The alluvial soils encountered range from 3.5 to 8.5 feet in
thickness, and predominantly consist of medium dense sands and gravels with varying amounts
j
of silt and trace cobbles. Below the alluvium, recessional outwash consisting of medium dense,
saturated, sand and gravel with variable silt content; and recessional lacustrine deposits,
consisting of silt and clay with occasional sand interbeds, were encountered. Borings BH-I I and
,
BH-12 were both terminated 41.5 feet below the existing ground surface, in glacial recessional
lacustrine or outwash soils. Ground water seepage was observed in both borings at an
approximate depth of 7.5 feet below the existing ground surface. BH-I I was completed as a
standpipe piezometer to allow for ground water level monitoring during the upcoming wet
weather season.
The soil units encountered in these borings are described below, with materials interpreted as
being youngest in origin and nearest the surface described first.
• Topsoil — Immediately at the ground surface, topsoil consisting of loose, dark brown, silty
fine sand was encountered. The topsoil layer ranged from 2 to 2.5 feet thick.
• Alluvium — Immediately beneath the topsoil in both borings, a layer of medium dense/stiff
alluvial soil consisting of olive brown to gray, clean to silty, fine sand with some scattered
fine gravel to gravel with silt and sand was encountered. This material appears to represent
native alluvial soil deposited by local fluvial processes. The thickness of alluvium at the
locations of BH-11 and 12 were about 3.5 and 8.5 feet, respectively. Typically, this soil is
suitable as foundation of non -critical, lightly loaded structures, due to low strength, increased
settlement potential, and susceptibility to liquefaction.
• Recessional Outwash — Beneath the alluvium, a layer of native glacial outwash, consisting
of primarily medium dense, gray, olive brown to gray, silt with sand and gravel to gravelly
silty sand, was encountered in the BH-I I and BH-12. This material appears to represent
deposited by from the front. The
native glacial outwash soil melt water receding glacial
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thickness of outwash at the location of BH-I I was 19 feet. In BH-12, recessional outwash
deposits appeared to be encountered below the alluvium at depths of between 9.5 to 22 feet,
and again below a layer of recessional lacustrine deposits at an approximate depth of 30 feet
below the existing ground surface. This soil should serve as an adequate foundation for the
wet well.
1 • Recessional Lacustrine — Beneath the recessional outwash sand and gravel layer in BH-11,
a layer of stiff clayey sand to sandy clay was encountered at an approximate depth of 30 feet
and was in excess of 16.5 feet thick. In BH-12, recessional lacustrine material was
encountered between two layers of recessional outwash at a depth of 22 feet and was 8 feet
thick (i.e. between 22 and 30 feet BGS). This material appears to represent native fine
grained glacial lacustrine deposits that formed within lakes created by temporary dams within
or marginal to the outwash channel. This material will provide an adequate foundation for
the wetwell.
1
3.3.9 Summary of Soil Conditions
To assist with an understanding of the soil conditions encountered at each of the investigated
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sites, we have compiled a tabulated summary of the various units, as indicated in Table 1.
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Table 1: Summary of Explored Soil Conditions
_Approximate
Anticipated Native Soil:
Anticipated Trench Fill or
`.-Project Stationing
'Vertical Succession
= -Native Soil, Conditions
(top=:�down)..
NE Field Avenue (Alignment from South to North)
Medium dense to loose, silty
From Station:2+00'
Fill=>Vashon Till
gravelly SAND(trench)-Dense to
to 11+30'
very dense, silty SAND with
gravel (native)
201h Street NE
Station: 18+30'
Fill=:>Weathered Till=>Vashon
Medium dense to very dense, silty
Till
SAND with gravel, moist.
Stonegate - Summerwind Connector
-&Dike east of existing
Fill�Vashon Till
Medium dense to very dense, silty
lift Station
SAND with gravel
West of manhole in
Fill=>Vashon Till
Medium dense to very dense, silty
NE 24`h Place
SAND with gravel.
NE 261h Street Culvert Crossing
At existing culvert
Fi11=>Alluvium=>Recessional
Medium dense, silty SAND with
crossing: Station
Lacustrine
gravel over stiff, lean CLAY.
26+04'
New Stonegate II Lift Station
North of existing
Fill=:>Alluvium=>Recessional
Medium dense to dense, gravelly
Stonegate Lift Station
Outwash and Lacustrine
SAND to silty GRAVEL over
stiff, lean CLAY
L]
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4.0 RECOMMENDATIONS
4.1 GENERAL
The following is a summary of our conclusions and recommendations based on the soil and
ground water conditions encountered in our explorations:
Temporary excavations for the lift station should be supported with a relatively
water -tight shoring system, such as interlocking steel sheet piles. Internally -braced
shoring is recommended. The contractor should be responsible to design and
install the temporary shoring.
• The lift station excavation will extend approximately 20 feet below ground water;
therefore, construction dewatering will be required. Dewatering should be
undertaken from the inside of the shoring system: to reduce the potential for
settlement -of the surrounding infrastructure. Driven interlocking sheet piling,
extending down to the glacial lacustrme layer, will tend to act as a seal and will
substantially reduce ground water flows into the excavation. Temporary
excavation support recommendations are presented in Section 4.2.1.
• Upsizing/replacement of the gravity sewer along NE Field Avenue can be
undertaken by either open trenching or pipe -bursting, as described in Sections 4.3
and 4.4 below.
• Dewatering will be required for the HDD or pipe jacking pits, or if the culvert
under -crossing along NE 26`h Street is undertaken using open -cut methods. Sumps
and pumps may be adequate in some locations; however, where the proposed sewer
invert extends significantly below the ground water level, dewatering wells or well
points will be required. Dewatering should be confined to the immediate area of
the trench to limit the potentially adverse effects of ground water drawdown on
adjacent properties.
4.2 STONEGATE II LIFT STATION
4.2.1 Temporary Shoring
We understand the new lift station will require an approximately 27-foot deep temporary
excavation. The excavation will extend about 20 feet below the existing ground water level. We
recommend a relatively water -tight shoring system, such as interlocking steel sheet piles, be
used.
The principal advantage of steel sheet piles over soldier piles and wood lagging is that
construction dewatering may be accomplished from within the shoring, without significantly
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lowering the ground water outside the shoring. The high permeability of soldier pile and lagging
shoring would require construction dewatering on the outside of the excavation. Because of the
proximity of the new lift station structure to the private property to the east and the existing
paved parking lot, dewatering induced settlement of the surrounding infrastructure should be
avoided.
Recommended design earth pressures for temporary braced shoring are presented in Figure 6.
The contractor should be responsible for the temporary shoring system design. Successful
installation and removal of the temporary shoring system is the responsibility of the contractor.
It may be somewhat difficult to drive the sheet piles through the existing dense glacial drift
underlying the lift station site. Therefore, we recommend sheet piling with a minimum web
thickness of/2-inch be used. Sheet piling sections with a thinner web thickness are prone to
installation damage when driving through dense sand and gravel. A large vibratory hammer
should be used to install the steel sheets, to ensure the required penetration is achieved.
Alternatively, thinner sheets might be used if the shoring alignment is predrilled to loosen the
deposits in advance of driving of the sheets. It will be the contractor's responsibility to select the
appropriate sheet piling and vibratory hammer for the job. The sheet piling may be extracted or
cut below ground surface and left in place when the lift station construction is completed and
backfilled.
4.2.2 Ground Water Control / Dewatering
Construction dewatering should be accomplished from within the relatively water -tight shoring
system, to limit drawdown exterior to the shoring. Silty to clayey glacial lacustrine soils,
consisting of stiff to very stiff sandy silt to clay, exists below 25 feet. This material has a much
lower permeability that the overlying clean to slightly silty sand and gravel. Driving sheet piles
into these fine-grained materials will cut-off ground water and substantially reduce flows into the
excavation.
One method of controlling ground water would be to drive the steel sheets down and into the
lacustrine layer, excavate in the wet to subgrade elevation, and then tremie-pour a concrete slab
("mud -slab"). Once the concrete has cured, the water above the mud slab could be pumped out
of the excavation. As a general and conservative rule of thumb, the thickness of the mud slab
should be approximately 40% of the ground water displacement depth. In this case, for ground
water approximately 6 feet below ground surface and the bottom of the overflow storage wet
well about 27 feet below ground surface, the thickness of the mud slab should be about 8'/z feet.
Leakage through joints in the steel sheets and along the mud slab/sheet pile interface may be
handled by using suitably sized sumps and trash pumps.
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Alternatively, dewatering wells could be installed on the inside of the shoring. The effectiveness
of the dewatering wells will depend on whether the sheet piles are keyed into the silt/clay layer.
The contractor should retain a dewatering specialist to design and operate the dewatering system.
4.2.3 Lift Station Excavation
Excavations for the lift station can be completed with conventional excavating equipment, such
as trackhoes. Although not encountered in our borings, there is a potential for logs to exist
within the alluvial deposits. The contract should, therefore, contain provisions for excavating
and dealing with oversize woody materials.
4.2.4 Buoyancy
As with other manhole structures, the lift station will need to be designed to resist hydraulic
buoyancy. Recommended parameters for calculating uplift resistance are presented in Figure 5.
We recommend the ground water be assumed to be at the ground surface for buoyancy resistance
design calculations.
S
4.3 PIPE BURSTING
Pipe bursting may be an economically feasible alternative to conventional open -cut trench and
pipe replacement methods due to the potentially timesaving, cost effective, and less disruptive
methodology inherent in the procedure. We understand that pipe bursting is being considered for
use during upsizing of the gravity conveyance system along the NE Field Avenue, where traffic
and pavement disruptions due to construction are to be minimized. Connections to existing side
sewers will, however, still require localized open cuts for access.
The pipe bursting process consists of in -situ fragmentation, displacement, and replacement of the
existing pipes with new polyethylene pipes of equal or larger diameter. Typically, the existing
pipe is split by a hydraulic or pneumatic bursting -head or nosecone to which the new
polyethylene pipe is attached. As the existing pipe is burst, the new polyethylene pipe is pulled
along the alignment of the old pipe. A chain or cable towline attached to a hydraulic jacking or
winch system is used to advance the bursting head. Typically, the polyethylene pipe installed
during the pipe bursting process consists of 20 to 40 foot sections that are welded together on
site. Pipe bursting is conducted between two points of access; i.e., station —to -station with
stations consisting of existing manholes, or insertion and extraction pits.
We understand that the existing pipes (8 inches in diameter) will be up -sized to 12 inches, to
handle the future sewage flows. Typically, the most common type of pipe bursting is size -for -
size; however, upsizing the diameter up to three sizes (e.g. 8-inch to 12-inch) is fairly routine
(TTC, 2001).
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For pipe bursting to be successful, information regarding the density of the existing soil backfill
and adjoining native materials is required. Accordingly, during our exploration program, several
of our borings were conducted within the existing sewer trenches in order to characterize the
engineering properties of the existing trench backfill. The results of our borings indicate that the
backfill in the vicinity of the existing pipes along NE Field Avenue is generally loose to medium
dense, which is a condition generally conducive to a pipe bursting operation.
Information regarding the proximity of other service lines or underground structures, and the
location of any documented prior service repairs that reinforce the existing pipe should be
evaluated. Such information is utilized to select the most appropriate pipe bursting methods and
tools, and to evaluate the potential effects of vibrations and ground. displacements, associated
with the bursting operations. Studies have shown that the vibrations caused by pipe bursting
tend to have a frequency range well above the natural frequency of buildings (TTC, 2001).
However, in areas of concern or at the beginning of the project, we recommend that vibration
monitoring be conducted to verify that pipe bursting efforts are not generating damaging levels
of ground vibration. In general, pipe bursting should not be used when the bursting head will
pass within 2.5 feet of other buried pipes and within 8 feet of sensitive surface structures (TTC,
2001). Where distances are less than those mentioned above, special provision should be made
to protect the existing structures, such as excavating (daylighting) at the crossing point to relieve
potential induced -stress on the existing pipe (TTC, 2001).
Favorable ground conditions for pipe bursting are reportedly within soils that can be moderately
compacted such that the enlarged hole behind the bursting head does not cave in before the
replacement pipe is installed. This scenario results in minimal lateral extent of outward ground
movement because the volume change is accommodated by the local soils. In addition, the lack
of caving behind the bursting head will result in lower drag and reduced tensile stress on the pipe
during installation (TTC, 2001). Less favorable ground conditions include densely compacted
soils or fills, and soils below the water table. These ground conditions tend to increase the force
required for the bursting operation.
Our borings indicate that the backfill in the vicinity of the existing pipe is relatively loose. It is
our opinion, therefore, that pipe upsizing by means of pipe bursting is feasible along NE Field
Avenue. However, the contractor should anticipate that variation in local fill soil conditions, and
the presence or absence of ground water, will affect the amount of force required to burst and
pull replacement pipe.
Some ground displacement should be expected as a result of a pipe bursting procedure.
Displacements tend to be localized, and develop in the direction of least resistance. The
magnitude and orientation of the displaced soil is largely dependent upon the degree of pipe
upsizing, the type and compaction level of the soil surrounding the pipe, and the depth of the
pipe. Typically, loose soils will undergo uniform displacement where more densely compacted
soils at the same depth will most likely exhibit vertical (heave) expansion. The localized
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restraining effect of strong soils along trench sides and bottom also serves to direct ground
movement upward above the pipe. Conversely, if the existing pipes were founded on weak soil,
displacement would be directed downward.
We understand that some of the existing pipes along the project alignment are as shallow as
5 feet below the existing ground surface. Pipe bursting conducted on pipes shallower than 8 to10
feet may cause ground movement (heaving) that may distort the existing road surface. We
recommend that some contingency provision be made to accommodate the rehabilitation of the
existing road surface where pipes are shallow and surface heaving results. Bursting of pipes
located deeper than 10 feet does not typically cause surface heaving problems.
1
Invariably, some surface disturbance along the existing alignment is necessary for the excavation
of jacking/receiving pits. These excavations can require an area on the order of 16 feet by 8 feet.
Side sewers, however, can be installed from a pit as small as 6 by 4 feet. Service connections to
the pipeline being burst are typically dug prior to bursting so that the connections are not
damaged and temporary bypass service can be provided during construction. These excavations
can induce localized upward movement of the replacement pipe as it passes the area creating a
slight hump in the pipeline profile. This problem can be minimized by excavating beneath the
pipe, as well as above the pipe at the service connection location (TTC, 2001).
As with any gravity system, maintaining the established grade is very important. As previously
described, the replacement pipe follows the alignment of the original pipe under most conditions.
However, because the bursting head has a larger diameter than the replacement pipe, a cavity is
developed in the soil, allowing the replacement pipe to take up different positions within the
cavity. Depending upon the local soil conditions, site conditions, and installation procedures the
following outcomes are anticipated:
1. If soil displacements are predominately upward, a larger new pipe will most likely be
situated with its centerline higher than the original pipe, but with a matching invert elevation.
2. If the soil displaces uniformly, the larger new pipe will be match the centerline of the original
pipe.
3. If the soil displacements are predominately downward, the larger new pipe will most likely
be situated with its crown matching the original pipe crown position, but with a lower invert
elevation.
4. Asymmetrical soil displacement, resulting from the restraining effects of adjacent buried
structures, can result in a lateral shift in new pipe position relative to the original.
Case histories suggest that, with careful planning, maintenance of the existing pipe grades is
achievable when close attention and frequent surveys are conducted. Sometimes, the presence of
unforeseen large boulders, and existing concrete pipe collars, CDF backfill, adjacent utilities and
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such, will prevent the advancement of the pipe bursting head or cause it to deflect above or
below the design invert level. These types of obstructions occur quite commonly despite the
amount of available subsurface data and/or as -built and maintenance records, and it is
recommended that contingencies be provided in the contract to deal with such problems if they
occur.
4.4 HORIZONTAL DIRECTIONAL DRILLING
The use of horizontal directional drilling (HDD) methods may be appropriate for use in
constructing the connector between the wet well at the existing Summerwind lift station and the
Stonegate gravity system in NE 24`h Court (See Figure 3), and the culvert under -crossing
required for the new force main alignment where it encounters a culvert on NE 261h Street (See
Figure 4C).
The Summerwind-Stonegate connector would likely be constructed by installing an 8-12-inch
OD HDPE pipe through the existing fill or native soils that overlie very dense native glacial till.
The connection is planned between the wet well at the Summerwind lift station and the existing
sanitary sewer manhole in NE 24 h Court; a horizontal distance of roughly 200 feet. We
understand that a narrow easement exists through this area which is situated along a property line
between two adjacent residential structures. Constructing a new pipeline along this alignment
using HDD will eliminate the need for open cuts, backfilling, dewatering and landscaping repair;
thereby, minimizing the potential impact to the existing private property.
The culvert under crossing along NE 26th Street involves installing an 8-12-inch OD HDPE pipe
through medium dense silty sand with gravel, beneath a culvert that is approximately 4.5 feet
high and 5.7 feet wide and with an invert elevation that is approximately 6-7 feet below the
existing road surface elevation. Constructing the new force main along this portion of the
alignment using HDD will eliminate the need for open cuts, culvert replacement, backfilling,
dewatering and pavement repair.
HDD is a trenchless methodology that involves drilling a small pilot hole, using technology that
allows the drill to be steered and tracked from the surface. The pilot hole is launched from the
surface at an angle, typically between 8 to 18 degrees to the horizontal, then transitioning to
horizontal as the required depth is reached. A bore path with a very gradual curvature or near
straight alignment is normally followed to minimize friction and to stay within the allowable
joint deflection and curve radius for the pipe. The pilot hole is enlarged by pulling back
increasingly larger reamers from the pipe insertion point (the recovery pit) to the rig side (entry
pit) until the hole is approximately 1.5 times the outside diameter of the new pipe. On the final
reamer pass, the new pipe is pulled behind the reamer back through the HDD path to the entry pit
on the rig side. I
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Because minimization of disturbance to the roadway prism is a key project objective,
consideration should be given to the utilization of this method for the pipeline marsh crossing.
Items due consideration and that may be of concern are:
• Location of all utilities along the alignment: All utilities within 20 feet of the proposed
bore path in three dimensions.
• Location of buried structures along the route. The HDD pipeline would extend below the
existing culvert crossing.
• The ability of the drill string to accommodate the required radius of curvature. Usually
the drill string requires a larger radius than the pipe. The radius is controlled by the
position of the entry and exit points and the entry angle.
• If HDD is selected, additional borings should be drilled to explore and define the vertical
and lateral limits of the fill/glacial soil contact along to the proposed Summerwind -
Stonegate Connector alignment.
4.5 OPEN CUT TRENCHING
Presently, open -cut trenching methods are planned for the installation of the force main required
to convey effluent from the new Stonegete II lift station to the tie-in location with the existing
Summerwind gravity system along NE 201h Street. Open -cut trenching techniques may also used
in support of pipe bursting to allow for the construction of insertion pits, service tie-ins,
manholes, etc. The following sections describe the methodology and outline our
recommendations for excavation, shoring, dewatering, pipe placement and trench backfilling.
4.5.1 Soil Excavation Characteristics
Excavations for the pipelines can be accomplished with conventional excavation equipment such
as backhoes and trackhoes.
4.5.2 Sloped Open -Cut Excavations
Maintenance of safe working conditions, including temporary excavation wall stability, should
be the responsibility of the contractor. All temporary cuts in excess of 4 feet in height should be
sloped in accordance with Part N of WAC (Washington Administrative Code) 296-155, or
should be temporarily shored. The fill, alluvial, and weathered till deposits generally classify as
Type C soil, per WAC 296-155, and should be sloped no steeper than I'/2H: l V
(horizontal: vertical). The glacial till soils in the project area generally classify as Type A soil,
and should be sloped no steeper than 3/4H:IV. These recommended allowable cut slope
inclinations are applicable to excavations above the water table only, and for conditions where
seepage is not occurring. Dewatering or flatter cut slopes will be required where ground water
i
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Based on the subsurface conditions observed during our exploration program along the proposed
sewer pipeline alignment, 2003 IBC Site Class D may be assumed for the project. The
generalized procedure outlined in the IBC should be utilized in determining the appropriate
response spectra for the project alignment.
Soil liquefaction is a phenomenon wherein saturated soil deposits temporarily lose strength and
behave as a liquid in response to moderate to severe earthquake shaking. Soil liquefaction is
generally limited to loose granular soils located below the water table. We expect that
liquefaction potential is highest within the area planned to accommodate the new Stonegate II lift
station which is underlain by layers of loose to medium dense saturated granular sands and
gravels that may liquefy during a moderately large seismic event. However, we anticipate
potential. liquefaction of lenses of soil above the new force main will be mitigated due to the
backfill over the trench being compacted and less prone to liquefaction than the existing soil.
Seismic induced landslide and ground surface rupture hazards were assessed for the force main
alignment and are considered to be negligible to low.
4.5 WET WEATHER EARTHWORK
Although silty glacial soils are moisture sensitive and wet weather earthwork is not
recommended when such soils are involved, such as within this project, general
recommendations relative to earthwork performed in wet weather or in wet conditions are
presented below. These recommendations should be incorporated into the contract
specifications.
• Earthwork should be performed in small areas to minimize exposure to wet weather.
Excavation or the removal of unsuitable soil should be followed promptly by the placement
and compaction of clean trench backfill. The size and type of construction equipment used
may need to be limited to prevent soil disturbance.
• Material used as trench backfill fill should consist of clean granular soil with less than
5 percent fines, which is a restriction on the trench backfill specification presented in
Section 4.2.8. The fines should be non -plastic. Native soils that do not meet these
requirements may be stockpiled for use in dry conditions or replaced with imported material.
• Surface water should be prevented from draining into the trench.
• Excavation and placement of structural fill material during wet weather should be observed
by a representative of the geotechnical engineer, to determine that the work is being
accomplished in accordance with the project specifications and the recommendations
contained herein.
Stonegate I1 Final Geotech Report.doc 28 HWA GeoSciences Inc.
i
I
November 7, 2008
HWA Project No. 2007-080-21 T1200
4.6 DRAINAGE AND EROSION CONSIDERATIONS
The native site soils are easily erodible when exposed and subjected to surface water flow.
Surface water runoff can be controlled during construction by careful grading practices.
Typically, these include the construction of shallow earthen berms and the use of temporary
sumps to collect runoff and prevent water from damaging exposed subgrades. All collected
water should be directed under control to a suitable discharge system.
Erosion can also be limited through the judicious use of silt fences and straw bales. The
contractor should be responsible for control of ground and surface water and should employ
sloping, slope protection, ditching, sumps, dewatering, and other measures as necessary to
prevent erosion of soils, consistent with best management practices required by the City of
Renton and other applicable regulatory agencies. In this regard, grading, 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 preliminary report in support of Roth Hill Engineering Partners, Inc.
design for the proposed Stonegate II Sewer System Improvement project in Renton, Washington.
Experience has shown that subsurface soil and ground water conditions can vary significantly
over small distances and over time; hence, we may not have seen every condition and even those
we saw can change with time.
The scope of our work did not include environmental assessments or evaluations regarding the
presence or absence of wetlands or hazardous substances in the soil, surface water, or ground
water at this site. HWA does not practice or consult in the field of safety engineering.
IStonegate II Final Geotech Report.doc
29 HWA GeoSciences Inc.
1
11
I
LEGEND
BH-1
* BOREHOLE DESIGNATION AND APPROXIMATE LOCATION
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HW(AGE05CIENCESINc Renton - Stonegate II -Sewer Improvements SITE AND CHECK BY
Renton, Washington EXPLORATION DATE PRoiEc Ho.
BASE FNP PROVIDED BY g PLAN 2007-080-21
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LEGEND
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mi,' I HWAGEOSCIENCES INC
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LEGEND
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BOREHOLE DESIGNATION AND APPROXIMATE LOCATION
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TASK X- X
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BOREHOLE DESIGNATION AND APPROXIMATE LOCATION
�
NEW
2007-080-21
1
H
�I
85psf
SURCHARGE
PRESSURE
I
62.4(H-5)
HYDROSTATIC
PRESSURE
22H
11
INTERNALLY BRACED
SHEET PILE WALL
i
BOTTOM OF
EXCAVATION
DESIGN WATER
r LEVEL INSIDE
f EXCAVATION
D
188D
ACTIVE NET PASSIVE
PRESSURE PRESSURE
NOTES:
'
1. GROUND WATER OUTSIDE SHORING ASSUMED TO BE 5FT BELOW GROUND SURFACE.
2. DESIGN PRESSURES ARE IN UNITS OF psf; DISTANCES ARE IN UNITS OF FEET.
3, SURCHARGE LOADS SHOULD BE ADDED WHERE APPROPRATE.
4. SHORING EMBEDMENT (D) SHOULD BE DETERMINED BY SOLVING EQaUILBRIUM EQUATIONS;
THE COMPUTED EMBEDMENT DEPTH SHOULD BE INCREASED BY 20 /o, AND D SHOULD BE NOT LESS THAN 15 FEET.
DESIGN EARTH PRESSURES FOR
TEMPORARY BRACED SHORING
DRAWN 8Y
RGUR6 NO.
6
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Phase II Geotechnical Engineering Services
DATE
PROJECT NO.
Renton - Stonegate II -Sewer Improvements
11.06.08
2007-080
Renton, Washington
9:\2007 PROJECTSl2007-080-21 STONEGATE II -SEWER SYSTEM IMPROVEMENTS\CAD 2CU7-080\EARTH PRESSURES.DWG 18.5xl l Figiue6> Plotted: 11/6/2D08 4:20 PM REV 00 EFx 0v09=
'
PROPOSED
BUOYANCY RESISTING
STRUCTURE
SOIL OVER EXPANDED BASE
DESIGN GROUNDWATER
LEVEL
1
WB
Fsw
H
W
a
Fss
3
a
..
Q. e<,
FB* B
* Buoyant force could result in high
,
bending
moments in slab
SYMBOL
ASSUMPTIONS
B =
Width of extended base in feet
Buoyant Soil Unit Weight = 68
pcf
Soil Friction Angle = 30'
W =Structure
weight in kips
At —rest Pressure Coefficient =
0.50 .
W B =
Buoyant soil weight above base
in kips
FB =
Buoyant force in kips
=
Unit weight of water x volume
of NOTES
structure below design ground —water
level Factor of Safety = W+Fsw L
L =
Perimeter around base of wall
in feet FB
(without extended base,
Fss =
Shearing resistance of soil
as indicated on the left side)
,
=
0.0084H2
(in kips per foot of wall)
Factor of Safety = W + WB +
FSS L
Fsw =
Shearing resistance of soil —wall
FB
'
=
contact 2
0.0053H
(with extended base
around perimeter of structure,
(in kips per foot of wall)
as indicated on the right side
of this figure)
'
FIBDRE 10.
7
'
PARAMETERS FOR CALCULATING DRAWN
UPLIFT RESISTANCE CHECKED
BY _M
BT EA
vPhase.11
M%GEOSCIENCES INC.
DATE
Geotechnical Engineering Services
PROJECT NO.
Renton - Stonegate It -Sewer Improvements
11.06.08
2007-080
Renton, Washington
SA2007 PROJECTS12007-080-21 STONEGATE II -SEWER SYSTEM IMPROVEMENTS\CAD 2007.08MEARTH PRESSURES.DWG <8.5x11 Figure7> Plored: 11/60008 3:41 PM
REV 00 EFK 01109M
H
APPENDIX A
FIELD EXPLORATIONS
I
I
I
I
IStonegate II Final Geotech Report.doc
HWA GeoSciences, INC.
I
RELATIVE DENSITY OR CONSISTENCY VERSUS SPT N-VALUE
COHESIONLESS SOILS
COHESIVE SOILS
Approximate
Approximate
Density
N (Nows/ft)
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
5W - 1000
Dense
30 to 50
65 - 85
Stiff
8 to 15
1D00 - 2000
Very Dense
over 50
85 - 100
Very Stiff
15 to 30
2000 - 4000
Hard
over 30
>4000
USCS SOIL CLASSIFICATION SYSTEM
MAJOR DIVISIONS
GROUP DESCRIPTIONS
Coarse
Gravel and
Clean Gravel
®'
GW
Well -graded GRAVEL
Grained
Gravelly Soils
(little or no fines)
Q
GP
Poorly -graded GRAVEL
Scas
o
More than
50% of Coarse
Gravel with
a
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)
SP
Poorly -graded SAND
50% Retained
50% or More
on No.
Sand with
SM
Silty SAND
200 Sieve
of Coarse
Fraction Passing
Fires (appreciable
Size
amount of fines)
SC
Clayey SAND
No. 4 Sieve
.'
ML
SILT
Fine
Silt
CL
Lean CLAY
Grained
and Liquid Limit
Soils
Less than 50%
Clay
_
—
OL
Organic SILT/Organic CLAY
MH
Elastic SILT
50% or More
Sill
Liquid Limit
Passing
and
of More
CH
Fat CLAY
No. 200 Sieve
Clay50%
Size
OH
Organic SILT/Organic CLAY
Highly Organic Soils
PT
PEAT
r tr
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 i1 to 3/4 in
Fine gravel
314 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. 4D (0.42 mm) to No. 200 (0.074 mm)
Silt and Clay
Smaller than No. 200 (0.074mm)
TEST SYMBOLS
%F
Percent Fines
AL
Alterberg Limits: PL = Plastic Limit
LL = Liquid Limit
CBR
California Bearing Ratio
CN
Consolidation
DD
Dry Density (pcf)
DS
Direct Shear
GS
Grain Size Distribution
K
Permeability
MD
Moisture/Density Relationship (Proctor)
MR
Resilient Modulus
PID
Photolonlzallon Device Reading
PP
Pocket Penetrometer
Approx. Compressive Strength (tsf)
SG
Specific Gravity
TC
Triaxlal Compression
TV
Torvane
Approx. Shear Strength (tsf)
UC
Unconfined Compression
SAMPLE TYPE SYMBOLS
® 20013 Split Spoon (SPT)
(140 Ib, hammer with 30 In. drop)
IShelby Tube
3-1/4" OD Split Spoon with Brass Rings
OSmall Bag Sample
® Large Bag (Bulk) Sample
® Core Run
Non-standard Penetration Test
(3.0" OD split spoon)
GROUNDWATER SYMBOLS
$� Groundwater Level (measured at
time of drilling)
Groundwater Level (measured in well or
open hole after water level stabilized)
COMPONENT PROPORTIONS
PROPORTION RANGE
DESCRIPTIVE TERMS
< 5%
Glean
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: MOISTURE CONTENT
Densifylconslstency, color, modifier (ifany) GROUP NAME, additions to group narne (Ifany), moisture DRY Absence of moisture, dusty,
content. PmporfPon, gradation, and angularity of constituents, additional comments. dry to the touch.
(GEOLOGIC INTERPRETATION) MOIST Damp Wl no visible water.
Please refer to the discussion in the report text as well as the exploration logs for a more WET Visible free water, usually
complete description of subsurface conditions.
soil is below water table.
GEOTECHNICAL DATA REPORT LEGEND OF TERMS AND
OVA SEWER REPLACEMENT ROUTE INVESTIGATION SYMBOLS USED ON
IMGEOSCIENCESINC. RENTON-STONEGATE-II EXPLORATION LOGS
RENTON, WASHINGTON
PROJECT NO.: 2007-080-21 FIGURE: A-1
LEGEND 2007-0BO.GPJ 10129/08
I
DRILLING COMPANY: Gregory Drilling Inc.
LOCATION: See Figure 2
DRILLING METHOD: Truck Mounted Hollow Stem Auger
DATE STARTED: 05/08/2008
SAMPLING METHOD: SPT w/Auto hammer
DATE COMPLETED: 05/08/2008
SURFACE ELEVATION: 416 t feet
LOGGED BY: T. Taddese
U)
U
J
J N
y y H
O�
5-
GID
w
m
X
z
�
W
Q.
w
w
0-
a
X�
a
w
z
Z)
0
DESCRIPTION
a n
O
0
Asphalt
GP Medium dense, gray, fine to coarse GRAVEL with fine to S-1 25-15- 10
coarse sand and trace silt.
(TRENCH FILL)
SM Medium dense, rust mottled, gray to yellowish gray, fine
gravelly, fine to medium SAND, moist
SM IMedium dense, light yellowish gray, fine to coarse gravelly,
fine to medium SAND, moist.
S-2 4-7-4
SM Dense, olive gray, silty, fine to medium SAND with fine gravel S-3 4'14-20
moist.
Borehole terminated at a depth of about 6 feet below existing
ground surface. No ground water seepage was observed
during drilling.
Standard Penetration Test
(140 lb. weight, 3U' drop)
A Blows per foot
LLJ
nL. v
10 20 30 40 50 0 w
s
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 condltlons applies only at the specified location and on the date indicated
and therefore may not necessarily be Indicative of other times and/or locations.
r0
-5
'— 10 I
100
GEOTECHNICAL DATA REPORT BORING:
gon SEWER REPLACEMENT ROUTE INVESTIGATION BH- 1A
IMIGEOSaENCES INC. RENTON-STONEGATE-11 PAGE: 1 of 1
RENTON, WASHINGTON
PROJECT NO.: 2007-080-21 FIGURE' A-2
BORING 2007-080.GPJ 10/29/08
Asphalt
GP
Medium dense, gray, fine to coarse GRAVEL with fine to
coarse sand and trace silt.
:.
SM
::.:
--------- (FILL)---------�
Dense, brown, fine gravely, silty, fine to medium SAND,
ML
moist.
SM
Very dense, olive gray, fine gravelly, silty, fine to medium
SAND to hard, fine gravely, fine to medium sandy SILT,
moist.
(VASHON GLACIAL TILL)
Dense to very dense, olive gray, fine to coarse gravelly, silty,
SM
fine to medium SAND, moist.
Trace organics noted at about 10 feet below existing ground
surface.
GEOTECHNICAL DATA REPORT BORING:
' SEWER REPLACEMENT ROUTE INVESTIGATION BH— 1 B
HWAGEOSCIENCES INC RENTON-STONEGATE-11 PAGE: 1 of 1
RENTON, WASHINGTON ,
PROJECT NO.: 2007-080-21 FIGURE: A-3
BORING 2007-OBO.GPJ 10129108
DRILLING COMPANY: Gregory Drilling Inc.
LOCATION: See Figure 2
DRILLING METHOD: Truck Mounted Holow Stem Auger
DATE STARTED: 05/08/2008
SAMPLING METHOD: SPT w/Auto hammer
DATE COMPLETED: 05/08/2008
SURFACE ELEVATION: 414 t feet
LOGGED BY: T. Taddese
IX m
z
W
Standard Penetration Test
a.
2
- 0
P
¢
(140 lb. weight, 30" drop)
z
V) .__
o
♦ Blows per foot
Lu
w
aI�
w
K is
_
i'�i
LU
W
~O
r _
DESCRIPTION v)
va)
a- 8
00
0
10 20 30 40
50
Asphalt
O GP Medium dense, gray, fine to coarse GRAVEL with fine to S-1a 12-8-7
° coarse sand and trace sill.
(TRENCH FILL)
SM Medium dense, gray and light yellow brown, silly, fine to
coarse gravely, fine to medium SAND, moist.
S-1b
S-2 4.6.5
ML Loose to medium stiff, light yellow brown and gray, silty, fine S-3 4.4.3
SM gravelly, fine SAND to fine sandy, fine gravely, SILT, moist.
Trace organics.
5-
Borehole terminated at a depth of about5.0 feel below
existing ground surface. No ground water seepage was
observed during drilling.
1 10-
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 tog 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.
0
....A
..............:....:....:....:.:..
....:............................................
r- 0
-5
1-10
0 20 40 60 80 100
Water Content (%)
Plastic Limit I--* —A Liquid Limit
Natural Water Content
GEOTECHNICAL DATA REPORT BORING:
SEWER REPLACEMENT ROUTE INVESTIGATION BH- 2A
RENTON-STONEGATE-II PAGE: 1 of 1
FmGEosaENCESINC. RENTON, WASHINGTON
PROJECT NO.: 2007-080-21 FIr,ItRF A-4
BORING 2007-080.GPJ 10129/08
GEOTECHNICAL DATA REPORT BORING:
�! SEWER REPLACEMENT ROUTE INVESTIGATION BH- 2B
IMGEOSCIENCH INC. RENTON-STONEGATE-11 PAGE , or
RENTON, WASHINGTON
PROJECT NO.: 2007-080-21 FIGURE: A'5
PZO 2007-OOO.GPJ 1=9108
01"DRILLING COMPANY: Gregory Drilling Inc.
LOCATION: See Figure 2
DRILLING METHOD: Truck Mounted Hollow Stem Auger
DATE STARTED: 05108/2008
SAMPLING METHOD: SPT w/Auto hammer
DATE COMPLETED: 05/08/2008
SURFACE ELEVATION: 431 t feet
LOGGED BY: T. Taddese
5
Co
w
Standard Penetration Test
0- _
d
vFNi
a
(140 lb. weight, 30" drop)
w
L
0
0 Blows per foot
w
a
w
z
C.
F
d
DESCRIPTION
d 8
O
_ __
_ o m
Asphalt
° Q
GP
Medium dense, gray, fine to coarse GRAVEL with fine to
coarse sand and trace silt.
(T_RE_NC_HFIL_L)________
SM
Medium dense, light yellow brown and olive gray, silty, fine to
coarse gravelly, fine to medium SAND, moist.
.................................................................
Loose, light brown, silty, fine gravely, fine to medium SAND,
SM
moist.
Loose, light yellow brown and strong brown, silty, fine to
SM
medium SAND with fine to coarse gravel, moist.
Borehole terminated at a depth of about 5.5 feet below
existing ground surface. No ground water seepage was
observed during drilling.
S-1 15-13-9
S-2 4-4-3
S-3 3-3-4
10 --1
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 indicagve of other times and/or locations.
I— 5
° 20 40 00 eo 100 10 Water Content (%)
Plastic Limit 1--0 Liquid Limit
Natural Water Content
:A
..... ..............:....:....:....:....:....
GEOTECHNICAL DATA REPORT BORING:
ffMA SEWER REPLACEMENT ROUTE INVESTIGATION BH- 3A
HMGEOSCIENCESINC. RENTON-STONEGATE-il PAGE: 1 of 1
RENTON, WASHINGTON
PROJECT NO.: 2007-080-21 FIGURE' A-6
BORING 2007-MO.GPJ 1Cr29108
I
Asphalt
GP
Dense, gray, fine to coarse GRAVEL with fine to coarse sand
I and trace sill.
(FILL - - - - - - - - - - - I - - - - - - - - -
SM—
Medium dense, olive gray and olive brown, fine to coarse
gravelly, fine to medium SAND, moist. Organics noted.
ML
Loose to medium stiff, olive gray to olive brown, fine gravelly,
SM
silty, fine to medium SAND to fine gravelly, fine to medium
sandy, SILT, moist. (WEATHERED TILL)
SM
Very dense, olive gray, fine to coarse gravelly, silty, fine to
medium SAND, moist.
(VASHON GLACIAL TILL)
F:
GEOTECHNICAL DATA REPORT BORING:
SEWER REPLACEMENT ROUTE INVESTIGATION BH- 3B
IMIGEOSCIENCES INC RENTON-STONEGATE-II PAGE: 1 of I
NGTON
BORING 2007-OBO.GPJ 10129108 RENTON, WASHI -- PROJECT NO.: 2007-080-21 FIGURE: A-7
DRILLING COMPANY: Gregory Drilling Inc.
LOCATION: See Figure 2
DRILLING METHOD: Truck Mounted Hollow Stem Auger
DATE STARTED: 05/08/200B
SAMPLING METHOD: SPTw/Auto hammer
DATE COMPLETED: 05/08/2008
SURFACE ELEVATION: 487 t feet
LOGGED BY: T. Taddese
w
Standard Penetration Test
Fv~i
040 lb. weight, 3U' drop)
z
W
0
o A Blows per foot
D
��
0
_
a
gg
0.
z'
w
x
O
ad
DESCRIPTION (D
0- a
O
(9 - — -- -- .-
_- o w
Asphalt
Medium dense, gray, fine to coarse GRAVEL with fine to S-1 0-11-13
coarse sand and trace silk
(TRENCH FILL)
_ _ _ _ _ _ _
Medium dense, light yellow brown, silty, fine gravelly, fine to
medium SAND, moist.
Medium dense, light yellow brown to reddish brown, fine I I J S-2 5-5-14
gravelly, fine to medium SAND, moist. Organics noted
SM Dense, olive gray, fine to coarse gravelly, silly, fine to medium S-3 0-18-15
SAND, moist.
5-
Borehole terminated at a depth of about 5.5 feet below
existing ground surface. No ground water seepage was
observed during drilling.
to -
F-1
A
-A
For a proper understanding of the nature of subsurface conditions, this o 20 40 so Bo
exploration log should be read in conjunction with the text of the Water Content (^io)
geotechnical report. Plastic Limit I— 0 I 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.
1-- 5
GEOTECHNICAL DATA REPORT BORING:
SEWER REPLACEMENT ROUTE INVESTIGATION BH- 4A
HMGEOSCIENCHINC, RENTON-STONEGATE-II PAGE: 1 of 1
RENTON, WASHINGTON
PROJECT NO.: 2007-080-21 FIGURE' A-$
BORING 2007A90.GPJ 10129= _
Asphalt
GP
Medium dense, gray, fine to coarse GRAVEL with fine to
coarse sand and trace silt. !
=, SM
i FILL ------
: Medium dense, light brown to olive brown, silly, fine gravelly,
fine to medium SAND, moist. Organics noted.
........................................ - ......... I.............
SM
Very dense, fight yellow brown, fine to coarse gravely, silty,
fine to medium SAND, moist. Trace organics noted.
-'.
SM
Dense to very dense, gray to olive gray, silly, fine to medium
SAND with fine to coarse gravel, moist.
(VASHON GLACIAL TILL)
GEOTECHNICAL DATA REPORT BORING: ,
SEWER REPLACEMENT ROUTE INVESTIGATION BH- 4B
IMGEOSCIENCH INC. RENTON-STONEGATE-11 PAGE: 1 of 1
RENTON, WASHINGTON
PROJECT NO.: 2007-080-21 FIGURE; A'9
BORING 2007-080.GPJ 10/29108
DRILLING COMPANY: Gregory Drilling Inc.
LOCATION: -See Figure 2
DRILLING METHOD: Truck Mounted Hollow Stem Auger
DATE STARTED: 05/07/2008
SAMPLING METHOD: SPT w/Auto hammer
DATE COMPLETED: 05/07/2008
SURFACE ELEVATION: 440 t feet
LOGGED BY: T. Taddese
5
1 10
1 15
1 20
DESCRIPTION
Asphalt
GP
Medium dense, gray, fine to coarse GRAVEL with fine to
t coarse sand and trace silt. I
---- — — — (FILL) — — — — !
Hard, dark brown, fine sandy, SILT with scattered fine gravel,
ML
.'. SM
moist. Organics noted.
Medium dense, olive gray, silty, fine to medium SAND with
scattered fine to coarse gravel, moist.
(WEATHERED TILL)
Very dense, olive gray, silty, fine to coarse gravelly, fine to
ML
SM
medium SAND to hard, fine to coarse gravelly, fine to medium
sandy SILT, moist.
'
(VASHON GLACIAL TILL)
.......................
SM
—...........................................
Very dense, olive gray and yellowish brown, silty, fine to
medium SAND, moist.
Trace organics noted between 15 and 16.5 feet below existing
ground surface.
....................................................................
Very dense, gray to dark gray, silty, fine to medium SAND
SM
with fine to coarse gravel, moist.
Lu m
w
O
z�
o
Standard Penetration Test
a 2
¢
(140 Ib. weight, 30" drop)
Lu w
w m
tw-
Z
A Blows per foot
<<
Z
W
Fi
a
rn
0- z
O
W
0
N
o w
0
10 20 30 40 50
S-1 13-16-32
S-2 10-9-10
S-3 5-15-13
SA 6-14-50/5"
S-6 16-34-5015'
NS-6 30-50/5"
NS-7 31-50/5"
25
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
:>>A
20 40 8n RA
Water Content (%)
Plastic Limit 1-- 40 —I Liquid Limit
Natural Water Content
,t-1c
1-1:
L 25
n
GEOTECHNICAL DATA REPORT BORING:
got, SEWER REPLACEMENT ROUTE INVESTIGATION BH- 5
HMGE0SaENC9INC. RENTON-STONEGATE-11 PAGE: / of 2
RENTON, WASHINGTON
PROJECT NO.: 2007-080-21 FIGURE A-10
BORING 2007-080.GPJ 10l28/08
GEOTECHNICAL DATA REPORT BORING:
ffmi SEWER REPLACEMENT ROUTE INVESTIGATION BH- 5
HMGEOSCIENCESINC. RENTON-STONEGATE-II PAGE: 2 of 2
RENTON, WASHINGTON '
PROJECT NO.: 2007-080-21 FIGURE: A"1 O
BORING 2007-M.GPJ 10/29/03
DRILLING COMPANY: Gregory Drilling Inc.
LOCATION: See Figure 2
ORILLING METHOD: Truck Mounted Hollow Stem Auger
DATE STARTED: 05/0712008
SAMPLING METHOD: SPT wlAuto hammer
DATE COMPLETED: 06/67/2008
SURFACE ELEVATION: 387 A feet
LOGGED BY: T. Taddese
N
U
J
J O
Lu to
0
iG
DESCRIPTION
Lu
W
U
Of
i}i
H N
F
� E
Q
h Z
F
Ld
o mof
n
asa i��i
w
of
a
o
ui tan
0 0
S-1
24-24-34
GP
Asphalt
Very dense, gray, fine to coarse GRAVEL with fine to coarse
sand and trace silt. I
GMGP
L--------- (FILL) ---------)
o
Dense, olive gray to olive brown, silty, fine to coarse sandy,
0
fine to coarse GRAVEL, moist.
0
SM
Dense, olive gray, silty, fine to medium SAND, molst.
Scattered fine gravel, moist.
(WEATHERED TILL)
----------------------
Very dense, olive gray, silty, fine to coarse gravely, silty, fine
. SM
to medium SAND, moist
(VASHON GLACIAL TILL)
Iz
S-2 10-23-25
8-3 14-14-23
Standard Penetration Test
(140 lb. weight, 30" drop)
A Blows per foot
x
Lu
�
10
20
30
40
50
n
0
:»
A
..................:....
S-4 32-5013 >>;
S-5 50/3" »
20
S-8 50/5"
Borehole terminated at a depth of about 20.4 feet below
existing ground surface. No ground water seepage was
observed during drilling.
25
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.
10 1
15 1
125
0 20 40 60 80 100
Water Content ("/e)
Plastic Limit F—®--i Liquid Limit
Natural Water Content
GEOTECHNICAL DATA REPORT BORING:
SEWER REPLACEMENT ROUTE INVESTIGATION BH- 6
HMIGEOSCIENCESINC. RENTON-STONEGATE-II PAGE: 1 of 1
RENTON, WASHINGTON
PROJECT NO.: 2007-080-21 FIGURE: A-11
BORING 2007-080.GPJ 10/29/08
GEOTECHNICAL DATA REPORT BORING:
SEWER REPLACEMENT ROUTE INVESTIGATION BH- 7
HWAGEOSCIENCES ING RENTON-STONEGATE-11 PAGE: 4 of 1
RENTON, WASHINGTON
PROJECT NO.: 2007-080-21 FIGURE: A-12
PZO 2007-080.GPJ 10129/08
GRILLING COMPANY: Davies Drilling
DRILLING METHOD: Track Mounted Hollow Stem Auger
SAMPLINGMETHOD: SPTw/Cathead
SURFACE ELEVATION: 410 t feet
5
1 10
=V
20
DESCRIPTION
LOCATION: See Figure 2
DATE STARTED: 05/08/2008
DATE COMPLETED: 05/08/2008
LOGGED BY: 0. Coltrane
�
m
w
z r
w Standard Penetration Test
}
rj
Q (140 lb. weight, 30" drop)
w w
w e
o A Blows per foot
a i
�5
o
w�
w
F
S
�
_
U)
a
O
O
w �
O
0 10 20 30 40
50
Asphalt
`. SM
Cuttings: Loose, light broom, to brown, silty sand with gravel.
(FILL)
I
SM
Medium dense, light brown, silty SAND with fine to coarse
gravel, wood bits, rootlets, moist.
(WEATHERED TILL)
SM
Medium dense to dense, light olive brown, silty SAND with
gravel, moist. Oxide mottling noted.
(VASHON GLACIAL TILL)
Gravelly drilling between 6.0 to 7.0 feet.
Dense to very dense, olive brown to light olive brown, silty,
SM
SAND with gravel, moist. Wetter zones in some of the sandlot
material.
Very dense, olive gray, SAND with silt and gravel to silty
SM
SAND with gravel, moist.
Driller notes less big gravels, smaller more angular gravels.
S-1 9-5-2
S-2 3-3-12
S-3 28-2-20
S-4 10-21-26
8-5 16.16-28
S-6 21-5016"
S-7 5011"
25 — — — — — — — — — — — — — — — — — — — — —
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 limes and/or locations therefore may not necessarily be indicative of other times and/or locations.
M
I
1 20
40
60
80
1
Water Content (%)
Plastic Limit (-- ®— { Liquid Limit
Natural Water Content
F— 5
1=
d-2[
GEOTECHNICAL DATA REPORT BORING:
SEWER REPLACEMENT ROUTE INVESTIGATION BH- 8
HMGEOSCIENCESINC RENTON-STONEGATE-II PAGE: 1 of 2
RENTON, WASHINGTON
PROJECT NO.: 2007-080-21 ' FIGURE A-1 3
BORING 2007-080.GPJ 10/29/08
DRILLING COMPANY: Davies Drilling
LOCATION: See Figure 2 1
DRILLING METHOD: Track Mounted Hollow Stem Auger
DATE STARTED: 05/0812008
SAMPLING METHOD: SPT wlCalhead
DATE COMPLETED: 05/08/2006
SURFACE ELEVATION: 410 t feet
LOGGED BY: D. Coltrane
v
J
J N
00 V1
a�
09 0 j
25 --1 rr-r r
1 30-
1 35 -
1 40-
1 45 —
1 50 —
w
(a
w
z
W
Standard Penetration Test
a. 2
1Q a)
Q
(140 lb. weight, 30" drop)
~
o
® Blows per foot
w
w
Z
x
a 0.
z
w
x
Z)
O
av
DESCRIPTION
�
o
O
O 0
10 20 30 40
50 a
Very dense, gray to olive gray, fine to medium SAND with silt
® S•6
40-500
25
and fine gravel, moist to wet. Perched water detected in sand
seam.
----------------------
Very dense, olive brown, silty SAND with gravel, moist to wet.
....,....,..............,..............,.........
.............>y. 30
S-9 5013^
Borehole terminated at a depth of about 30.25 feet below = =
.................................................
existing ground surface. Ground water was observed
between 23 to 28 feel below existing ground surface.
.............. :....:....:....:....:....:.... 35 .
:....:....:....:....:....:....:....:....:.... 40
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 limes andlor locations.
45 1
. r-50
0 20 40 60 80 100
Water Content (%)
Plastic Limit 1 0 Liquid Limit
Natural Water Content
GEOTECHNICAL DATA REPORT BORING:
SEWER REPLACEMENT ROUTE INVESTIGATION BH— 8
HMGEOSCIENCES INC. RENTON-STONEGATE-11 PAGE: 2 of 2
RENTON, WASHINGTON
PROJECT NO.: 2007-080-21 FIGURE: A-1 3
BORING 20e7-0e0.GPJ 10/29108
DRILLING COMPANY: Davies Drilling SURFACE ELEVATION: 398.00 t feet DATE STARTED: 05/08/2008
DRILLING METHOD: Track Mounted Hollow Stem Auger DATE COMPLETED: 05108/2008
SAMPLING METHOD: GIRT w/Cathead LOGGED BY: D. Coltrane
LOCATION: See Figure 2
MEQ
1 15
I 20
1 25
ofW
w
m
U
Standard Penetration Test
a
;
m
U
(140 lb. weight, 30" drop)
z
F
A Blows per foot
a
(L
w
Ow
H
a
o
o
DESCRIPTION U)�
8
a V)
0
10 20 30 40
50
—n
SM
Medium dense, light brown, silty SAND with gravel, moist.
Contains small wood particles.
SM
(FILL)
............I .............. ..... ........................
Medium dense, brown to gray brown, silty SAND with gravel,
moist. Contains wood particles and trace oxide mottling.
... ............................................
Medium dense, dark gray brown, silly SAND with gravel, wood
SM
particles, burnt wood, moist.
•;
:'
..........................................................
Medium dense, gray to gray brown, silty SAND, moist to wet.
r. SM
Trace rootlets and oxide mottling. Becomes SAND with sill at
about 9 feet.
.............................................................
Medium dense, light olive brown, silty SAND with gravel,
�j]I
SM
moist to wet. Contains some cleaner sand seams.
if/Ly1Y
Perched water noted at about 13.5 feel
SM
Very dense, olive gray, silty SAND with gravel to trace gravel,
moist Some oxide mottling.
(VASHON GLACIAL TILL)
Some sand seams detected.
S•7 14-50/5.5"...... ......... ..... ..... ..... ..... : »Art-- 20
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.
:>> — 25
0 20 40 60 80 100
Water Content (%)
Plastic Limit 1--8 Liquid Limit
Natural Water Content
GEOTECHNICAL DATA REPORT BORING:
SEWER REPLACEMENT ROUTE INVESTIGATION BH— 9
HWAGEOSCIENCES INC. RENTON-STONEGATE-II PAGE: 1 of 2
RENTON, WASHINGTON
PROJECT NO.: 2007-080-21 FIGURE: A-14
PZO 2007-0SO.GPJ 110t29/08
GEOTECHNICAL DATA REPORT BORING:
SEWER REPLACEMENT ROUTE INVESTIGATION BH- 9
HMISEOMENCESINC. RENTON-STONEGATE-II PAGE: 2 of 2
RENTON, WASHINGTON
PROJECT NO.: 2007-080-21 FIGURE: A-1 4
PZO 2007-080.GPJ 10/29/00
DRILLING COMPANY: Gregory Drilling Inc.
LOCATION: See Figure 2
DRILLING METHOD: Truck Mounted Hollow Stem Auger
DATE STARTED: 05/08/2008
SAMPLING METHOD: SPT w/Auto hammer
DATE COMPLETED: 05108/20DB
SURFACE ELEVATION: 375 t feet
LOGGED BY: T. Taddese
5-
10-
15-
20 -
25 -
DESCRIPTION
3-inch thick layer of asphalt over 3-inch thick layer of crushed
SP
Abase course.
SM
From 0 to 7 feet a vactor truck was used to remove the
material due to utility restrictions. The material removed was
observed and logged, but no samples were collected. Material
consisted of Gray, gravelly SAND with silt
Medium dense, mottled gray and orangish brown, sandy SILT
:. SM
to silty SAND with gravel and cobbles, moist.
[FILL]
°
-------------------
Very loose, gray, poorly graded fine GRAVEL with sand and
GP
trace silt, moist.
oO
°
[BEDDING MATERIAL]
SM
Very dense, light gray brown, silty SAND with gravel, moist.
[GLACIAL TILL]
Very dense, light olive gray, silty SAND with gravel, moist.
Broken gravels 16 sampler.
Very dense, light olive brown, silty SAND with gravel, moist.
Very dense, light olive gray, silty SAND with gravel, moist.
Boring was terminated at 20.5 feet below ground surface. No
ground water seepage was observed while drilling this
exploratory boring.
w
U
m
z -
w
F-
EL
Z
~ L
U
~
W
Q
w
In
w
>-
z
a a
�Z3
w
0
Z
v¢i
a r3
o
( _
S-1 3.3-3
S-2 2-2-1
® S-3 50/6
N SA 50/5
® S-5 50/5
N S-6 5016
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)
0 Blows per foot
10 20 30 40
x
Luv
50 0 °w'
i r— 0
5
10 1
20 1
' L 25
0 20 40 60 80 100
Water Content (%)
Plastic Limit 1 40 Liquid Limit
Natural Water Content
GEOTECHNICAL DATA REPORT BORING:
SEWER REPLACEMENT ROUTE INVESTIGATION BH-10
HMGEOSCIENCESINC, RENTON-STONEGATE-II PAGE: 1 of 1
RENTON, WASHINGTON
PROJECT NO.: 2007-080-21 FIGURE: A-1 5
BORING 2007-080.GPJ tOr29108
SM
(TOPSOIL)
J.:Loose,
brown, silty SAND with wood pieces, rootlets, and
burnt wood...
SC
[ALLUVIUM]
Loose, light brown, clayey, fine SAND with trace gravel, mist
to wet. Trace rootlets, mottled coloring noted.
Medium dense, olive brown, clayey, fine SAND, With beds of
clay. Trace fine to coarse gravel.
(RECESSIONAL OUTWASH)
Medium dense to dense, brown to light brown, fine gravely.
-9
fine to coarse SAND, to sandy, fine to medium GRAVEL, wet.
Or..
.
Subrounded and subangular gravel and sand.
Initial ground water seepage encountered at 7.5 feet below
ground surface.
Becoming silty at about 10 feet.
Medium dense, brown to dark brown, fine gravelly, medium to
coarse SAND with sill, wet
Dense, light brown, fine to medium sandy, fine GRAVEL with
wet..
OM
-silt,
r
Interbed of light brown, silty, fine to medium GRAVEL. /
ICY/yell
6'.
Dense, fight brown, sandy fine to medium GRAVEL with silt,
wet.
C.
h:
L&--'.
- - - - - - - - - - - - - - - - - - - - - -
GEOTECHNICAL DATA REPORT BORING:
SEWER REPLACEMENT ROUTE INVESTIGATION BH-1 1
HIAGEOSCIENCHNC. RENTON-STONEGATE-II PAGE: I of 2
• RENTON, WASHINGTON PROJECT NO.: 2007-080-21 FIGURE: A-16
PZO 2007-080.GPJ 10129108
DRILLING COMPANY: Davies Drilling SURFACE ELEVATION:
320.00 t feet
DATE STARTED: 05/07/2008
DRILLING METHOD: Track Mounted Hollow Stem Auger
DATE
COMPLETED: 05/07/2008
SAMPLING METHOD: SPT w/Cathead
LOGGED BY: D. Coltrane
LOCATION: See Figure 2
of
w
m
U
Standard Penetration Test
va
U
N
w U
(140 lb. weight, 30" drop)
-+ O
w
w .5
W
I¢
0 Blows Per foot
v)
`r')
W o
i
Kca
g
=
a
0-d
2 c
x
Nx
1
a w
ai � DESCRIPTION
W a)
ii p
O
a (n
0 10 20 30 40 50
a
25
CL
S$
7 6-9
25
Stiff, gray, sandy, silty CLAY with trace clay beds, and trace
ML
AL
%F '.'
gravel, moist to wet
(RECESSIONAL LACUSTRINE)
®'
S-9
7-9-9
AL
______ _______ ______
:. SC Interbed of clayey fine to medium SAND wth rootlets, wet. —
—
%F ,•
30
Medium dense, gray, sandy CLAY, moist to wet. Laminar
S-10
5-6-8
:•'
GS •.
::•;
......®:..A ................
30
bedding, trace gravel.
Medium dense to dense, gray, sandy CLAY with trace gravel
S-11
7-14-17
GS
and interbeds of sandy Gay, moist to wet- Laminar bedding
Sc
—
35
Shelby tube sample driven 23 inches.
S-12a
:....:....:....:.... :....:....:....:....:....
35
0-6" Dark gray, clayey SAND, moist.
S-12b
6-16" Dark gray, poorly graded SAND with clay, moist.
16-23" Dark gray, poorly graded SAND with clay and gravel,
S-12c
moist.
Medium dense, gray, clayey SAND with trace gravel, moist.
S-13
11-12-22
GS
40
----------------------
CL Stiff, gray sandy silty CLAY with gravel, moist.
:.. :.
40
ML
5-10-12
AL
�S-14
%F
Borehole terminated at a depth of about 41.5 feet below
existing ground surface. Ground water seepage was
encountered at 7.5 feet below the ground surface during the
exploration. A piezometer was installed in the exploration with
screen from 25-35 feet below ground surface.
45
....:....:........:....:....:....:....:....:....
45
50
50
0 20 40 60 80 100
Water Content (%)
Plastic Limit F—O—A 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.
GEOTECHNICAL DATA REPORT BORING:
SEWER REPLACEMENT ROUTE INVESTIGATION BH-11
HMGEOSCIENCES INC, RENTON-STONEGATE-II PAGE: 2 of 2
RENTON, WASHINGTON
PROJECT NO.: 2007-080-21 FIGURE: A-16
PZO 20D7-080.GPJ 10/29/08
SM
[fOPS01L]
Loose, brown, silty SAND, with gravel. Contains pockets of
light brown, silty sand, with wood pieces, and rootlets.
(ALLUVIAL SANDS AND GRAVELS)
Medium dense to very dense, grayish brown to brown,
0 •
gravelly SAND with silt, moist. Sample driven on rock.
0
oQ
Silt content increases.
D
Q.
Very dense, dark brown, poorly graded GRAVEL with sand
:Escand
silt, moist. Sample driven on rock. Wood pieces/twigs
A•.
noted. Sand becomes fine to coarse and gravel becomes fine.
n ,
Medium dense, brown, sandy GRAVEL with silt, wet. Sampler
.Q.'
wet at 7.5 feet. Gravel is rounded to sub -rounded.
tY .:
•
(RECESSIONAL OUTWASH)
Dense, dark yellowish brown, well graded GRAVEL with sand,
�t]i
=i
wet. Sub -angular gravel is present.
I�I�y1i
Medium dense, brown, sandy well graded GRAVEL, with silt,
• � •'
•
wet. '
Becomes sillier at about 16.0 feet. Some heave in sample.
y;;�•
Gravel is sub -rounded to sub -angular.
0
GM
Dense, gray, silty GRAVEL with medium to coarse sand, wet.
Gravel is sub -angular to sub -rounded. Drilling becomes less
°
gravely at 22 feet below ground surface.
ML
Medium dense, gray, sandy SILT, moist to wet.
(RECESSIONAL LACUSTRINE)
GEOTECHNICAL DATA REPORT BORING: ,
MMSEWER REPLACEMENT ROUTE INVESTIGATION BH-12
HWAGEOSCIENCES INC. RENTON-STONEGATE-11 PAGE: 1 of 2
RENTON, WASHINGTON
PROJECT NO.: 2007-080-21 FIGURE: A-1 7
BORING 2007.080.GPJ IM9108 '
DRILLING COMPANY: Davies Drilling
LOCATION: See Figure 2
DRILLING METHOD: Track Mounted Hollow Stem Auger
DATE STARTED: 05/07/2008
SAMPLING METHOD: SPT w/Cathead
DATE COMPLETED: 05/07/2008
SURFACE ELEVATION: 319 :it feet
LOGGED BY: D. Coltrane
U
J
J 0
oD:
25
1 3C
MP
1 4(
1 45
DESCRIPTION
w
�
0.
1-;L
N
~
Wto
U
W
W
z
a a
0
w
x
CL
Very stiff, gray, sandy SILT, moist. Contains scattered layers
of silt/clay at about 25.0 feet.
Stiff, gray, SILT with sand, moist.
`. SM
Medium dense, gray, silty. SAND with gravel, wet.
(RECESSIONAL OUTWASH)
Silt content decreases at about 30.5 feet.
Medium dense, gray, fine to medium SAND, with silt, wet.
Interbeds of sillier sand from about 32.5 to 33 feet.
SP
No Sample recovery from this depth. Drilling action was
SM
consistent with the recessional outwash material encountered
from 30 to 34 feet below ground surface.
5 feet of heave noted from about 35 to 40 feet.
O
No sample recovery. Blow counts most likely accurate.
No sample recovery. Blow counts most likely affected by
L ..
L.
heave.
O
Borehole terminated at a depth of about 41.5 feet below
existing ground surface. Ground water seepage was
observed at a depth of approximately 7.5 feet below the
existing ground surface and measured at 8.0 feet below
ground surface after the removal of the casing.
S-8 6-10-10 GS
S-9 6-7-8 %F
S-10 14-12-6 GS
S-11 9-6-14 %F
S-12 3-9-11
5-13 1-12-3
50--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.
Standard Penetration Test
(140 lib. weight, 3(r' drop)
♦ Blows per foot
I 1V N
.1V
9V O'
...A ...........:....:....:....:....
x
a�
1
C3
r— 25
1-30 1
1-40 1
1— 45 1
0 20 40 60 80 100
Water Content (%)
Plastic Limit F--" Liquid Limit
Natural Water Content
GEOTECHNICAL DATA REPORT BORING:
SEWER REPLACEMENT ROUTE INVESTIGATION BH-12
HMGEOSCIENCESINC. RENTON-STONEGATE-II PAGE: 2 of 2
RENTON, WASHINGTON
PROJECT NO.: 2007-080-21 FIGURE: A-1 7
BORING 2007-080.GPJ 10/29108
IN
IN
SYMBOL
SAMPLE
DEPTH (ft)
CLASSIFICATION OF SOIL- ASTM D2487 Group Symbol and Name
% MC
LL
PL
pl
Gravel
Sand
Fine
GRAVEL
SAND
SILT
CLAY
Coarse
Fine
Coarse
Medium
Fine
.
I
Uffl,
es
®
BH- 7
S-3
7.5 - 9.0
(SM) Brown, silty SAND
24
0.8
79.8
19.3
®
BH- 7
S-4
10.0 - 11.5
(ML) Yellowish brown, SILT with'sand
23
0.0
72.9
®
BH- 7
S-7
20.0 - 21.5
(SM) Yellowish brown, silly SAND
8
0.0
12.7
IGE®SCIENCES INC.
NwncHsz zcx�i•ouo.GN� iorzoroe
GEOTECHNICAL DATA REPORT PARTICLE -SIZE ANALYSIS
SEWER REPLACEMENT ROUTE INVESTIGATION OF SOILS
RENTON-STONEGATE-II METHOD ASTM D422
RENTON, WASHINGTON
PROJECT NO.: 2007-080-21 FIGURE:
IN in
IN
Milli
Milli
�II
GRAVEL
SAND
SILT
CLAY
Coarse
Fine
Coarse
Medium
ine
SYMBO
U
SAMPLE
DEPTH (ft)
CLASSIFICATION OF SOIL-ASTM D2487 Group Symbol and Name
% MC
LL
PL
plGravel
Sand
Fio es
®
BH-11
S-3
5.0-6.5
(SC) Olive brown, clayey SAND
19
29
18
11
0.0
35.7
®
BH-11
S-8
25.0 - 26.5
(CL-ML) Gray, sandy silly CLAY
20
23
17
6
0.0
65.0
A
BH-11
S-9
27.5 - 29.0
(SC) Gray, clayey SAND
162213
9
0.0
42.3
GEOTECHNICAL DATA REPORT PARTICLE -SIZE ANALYSIS
�®SEWER REPLACEMENT ROUTE INVESTIGATION 4F SOILS
I�NAGEOSCIENCESANC. RENTON-STONEGATE-II METHOD ASTM D422
RENTON, WASMINGTONPROJECT N0.' 20O7-OSO-21 FIGURE: B-4
HWAGRSZ 2007.060.GPJ 10/29108
�1�gm
I II
�
IIII
SYMBOL
SAMPLE
DEPTH (ft)
CLASSIFICATION OF SOIL- ASTM D2487 Group Symbol and Name
% MC
LL
PL
p�
Gravel
Sand
Fines
GRAVEL
SAND
SILT
CLAY
Coarse
Fine
Coarse
Medium
Fine
®
BH-11
S-10
30.0 - 31.5
(CL) Gray, sandy CLAY
17
9.6
36.6
53.8
®
BH-11
S-11
32.5 - 34.0
(CL) Gray, sandy CLAY
21
0.0
65.2
®
BH-11
S-13
37.5 - 39.0
(SC) Gray, clayey SAND
22
7.3
48.7
44.1
GEOTECHNICAL DATA REPORT PARTICLE -SIZE ANALYSIS
� ® .SEWER REPLACEMENT ROUTE INVESTIGATION OF SOILS
IG�OSCIENCES INC. RENTON-STONEGATE-II METHOD ASTM D422
RENTON, WASHINGTON PRoJEcrNo.: 2007-080-21 FIGURE: g-5
�11
111��
I
�I�IR
11
1
�II�
;■:IAII
IIIIIIIIIIIIIIIINIIII
01111,
SYMBOL
SAMPLE
DEPTH (ft)
CLASSIFICATION OF SOIL- ASTM D2487 Group Symbol and Name
% MC
LL
PL
pl
Gravel
GRAVEL
SAND
SILT
CLAY
Coarse
Fine
Coarse
Medium
Fine
Sand
Fines
®
BH-11
S-14
40.0 - 41.5
(CL-ML) Gray, sandy silty CLAY
18
22
15
7
0.0
57.1
®
BH-12
S-3
5.0 - 6.0
(GP -GM) Dark brown, poorly graded GRAVEL with sand and silt
10
56.6
35.0
8.4
®
BH-12
S-5
10.0 - 11.5
(GW) Dark yellowish brown, well graded GRAVEL with sand
11
67.3
30.1
2.6
GEOTECHNICAL DATA REPORT PARTICLE -SIZE ANALYSIS
� ® SEWER REPLACEMENT ROUTE INVESTIGATION OF SOILS
IIi�.GEOSCIENCESINC. RENTON-STONEGATE-II METHOD ASTM D422
RENTON, WASHINGTON
PROJECT NO.: 2007-080-21 FIGURE: B-IJ
HWAGRSZ 2007.00O.GPJ 10129108
SHE Ila
"iI �:: SI�II�OBI�N
011
SYMBOL SAMPLE DEPTH (ft) CLASSIFICATION OF SOIL- ASTM D2487 Group Symbol and Name % MC LL PL pl Gravel Sand Fines
GRAVEL
GRAVEL
SAND
SILT
CLAY
® BH-12 S-8 25.0 - 26.5 (ML) Gray, sandy SILT 23 0.0 35.7 64.3
IsBH-12 S-9 27.5 - 29.0 (ML) Gray, SILT with sand 27 0.0 71.4
® BH-12 S-10 30.0 - 31.5 (SM) Gray, silty SAND with gravel 18 16.3 63.1 20.6
GEOTECHNICAL DATA REPORT PARTICLE -SIZE ANALYSIS
"® SEWER REPLACEMENT ROUTE INVESTIGATION OF SOILS
I-iWA.GE®SCIEN�S INCRENTON-STONEGATE-II METHOD ASTM D422
RENTON, WASHINGTON
PROJECTNO.: 2007-080-21 FIGURE: B-7
GEOTECHNICAL DATA REPORT PARTICLE -SIZE ANALYSIS
"® SEWER REPLACEMENT ROUTE INVESTIGATION OF SOILS
I-iWA.GE®SCIEN�S INCRENTON-STONEGATE-II METHOD ASTM D422
RENTON, WASHINGTON
PROJECTNO.: 2007-080-21 FIGURE: B-7
am IIIIIIIIIIIIIIII Ii ft- II= IIIIIIIIIIIIIIIII W" IWII 0" No an no �_ No OWN
��I
mu■��0
��ii
INK
GRAVEL-
SAND
SILT
CLAY
D2487 Group Symbol and Name % MC LL PL PI Gravel Sand Flo es
® BH-12 S-11 32.5 - 34.0 (SM) Gray, silty SAND 22 0.0 23.9
® BH-13 S-11 30.0 - 31.5 (CL) Olive gray, lean CLAY with sand 22 37 21 16 0.0 76.9
® BH-14 S-1 2.5 - 4.0 (SM) Grayish brown, silty SAND 9 27.9 58.4 13.7
GEOTECHNICAL DATA REPORT PARTICLE -SIZE ANALYSIS
' ® SEWER REPLACEMENT ROUTE INVESTIGATION OF SOILS
I�A.GE®SCIENCES�dC. RENTON-STONEGATE-II METHOD ASTM D422
RENTON, WASHINGI-ON
PROJECT NO,: 2OO7-080-21 FIGURE: B-$
I-IWAGRSZ 2007-060.GPJ 10/29108
GEOTECHNICAL DATA REPORT PARTICLE -SIZE ANALYSIS
' ® SEWER REPLACEMENT ROUTE INVESTIGATION OF SOILS
I�A.GE®SCIENCES�dC. RENTON-STONEGATE-II METHOD ASTM D422
RENTON, WASHINGI-ON
PROJECT NO,: 2OO7-080-21 FIGURE: B-$
I-IWAGRSZ 2007-060.GPJ 10/29108
60
CL
CH
50
LL
X
40
W
Z_
30
U
H
20
�
o
10
s
CL-ML
ML MH
0
0
20
40 60
80
100
LIQUID LIMIT (LL)
SYMBOL
SAMPLE
DEPTH (ft)
CLASSIFICATION
% MC
LL
PL
PI
%Fines
®
BH-11
S-3
5.0 - 6.5
(SC) Olive brown, clayey SAND
19
29
18
11
35.7
GEOTECHNICAL DATA REPORT LIQUID LIMIT PLASTIC LIMIT AND.
W.
SEWER REPLACEMENT ROUTE INVESTIGATION PLASTICITY INDEX OF SOILS
RENTON-STONEGATE-II METHOD ASTM D4318
I-GEOSCIEt�10ESINC. RENTON, WASHINGTON PROJECT NO.: Z00%-OSO-21 FIGURE: B-9
UA